US20050183906A1 - Lubricating-Fluid Infusion Apparatus - Google Patents
Lubricating-Fluid Infusion Apparatus Download PDFInfo
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- US20050183906A1 US20050183906A1 US10/906,495 US90649505A US2005183906A1 US 20050183906 A1 US20050183906 A1 US 20050183906A1 US 90649505 A US90649505 A US 90649505A US 2005183906 A1 US2005183906 A1 US 2005183906A1
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16N—LUBRICATING
- F16N7/00—Arrangements for supplying oil or unspecified lubricant from a stationary reservoir or the equivalent in or on the machine or member to be lubricated
- F16N7/14—Arrangements for supplying oil or unspecified lubricant from a stationary reservoir or the equivalent in or on the machine or member to be lubricated the lubricant being conveyed from the reservoir by mechanical means
Definitions
- the present invention relates to lubricating-fluid infusion apparatuses for dispensing lubricating fluid into dynamic-pressure bearing devices employed in signal record/playback devices such as hard-disk drives.
- Fluid dynamic-pressure bearings have to date been employed in spindle motors used in signal record/playback devices such as hard-disk drives.
- Fluid dynamic-pressure bearings provide journal support by producing fluid pressure in a lubricant, such as a lubricating fluid, interposed in between a shaft and sleeve.
- FIGS. 10A and 10B Single examples of spindle motors that employ a dynamic-pressure bearing of this sort are illustrated in FIGS. 10A and 10B .
- the spindle motor in FIG. 10A is fit out with a dynamic-pressure bearing device 50 , in which a lubricating-fluid taper seal section 53 is formed, in a single location only.
- the motor's shaft 51 is inserted into a sleeve 52 , wherein radial dynamic-pressure bearings 55 , 55 support radially directed load on the motor.
- Mounted on the shaft 51 at its tip is a thrust plate 56 where thrust bearings 58 , 58 that bear axially directed load on the motor are formed.
- the bottom portion of the sleeve 52 is closed off by a thrust bushing 57 , wherein the bearing gap extending from the lubricating-fluid boundary surface in the taper seal section 53 to the shaft tip is filled with the lubricating fluid, without any places in which the fluid is interrupted.
- the open portion of the bearing device, where the bearing gap meets the external air, is in the upper end only, and is where the taper seal section 53 is formed.
- a bearing-device structure of this sort is highly reliable in that the surface area of contact between the lubricating fluid and the external air is small, and thus neither the mixing of air bubbles into, nor the gasification of, the lubricating fluid is liable to occur. Nonetheless, in order to inject lubricating fluid into the bearing device, air must be discharged ahead of time from the bearing gap, making equipment for that purpose necessary.
- the spindle motor in FIG. 10B is fit out with a dynamic-pressure bearing device 5 ′, in which the open portions of the bearing gap are in two locations, above and below, which puts the taper seal sections 53 , 53 in the two locations above and below.
- a dynamic-pressure bearing device 5 ′ in which the open portions of the bearing gap are in two locations, above and below, which puts the taper seal sections 53 , 53 in the two locations above and below.
- Methods such as follows are examples of techniques for injecting lubricating fluid into the bearing gap, after air filling the gap has been discharged, in dynamic-pressure bearing devices like device 50 or 5 ′ discussed above.
- One is a method in which the bearing device and a container filled with lubricating fluid are put into a vacuum chamber, and with the chamber in an evacuated state, the open portion of the bearing gap is either immersed in lubricating fluid or is submerged within lubricating fluid, after which air is introduced into the vacuum chamber to repressurize it.
- the air pressure applied in repressurization forces the lubricating fluid soundly into the full depth of the bearing gap.
- the lubricating fluid sticks to the outside of the bearing device.
- lubricating fluid having adhered to the outside of the bearing device becomes a cause of fluid contaminating the disk(s).
- the adhered lubricating fluid therefore must be carefully wiped off, which makes necessary a manufacturing process step that significantly impairs productivity.
- the lubricating fluid permeates the screw-hole and the thread groove. Removing lubricating fluid that has permeated a narrow area of this sort in the bearing device is extremely difficult.
- An alternative technique is a method in which the bearing device is set inside a vacuum chamber, and with the chamber in an evacuated state a cylindrical capillary tube such as a fine syringe needle is used to trickle lubricating fluid into the open portion, or the taper seal section, of the bearing device, following which the chamber is repressurized.
- a manufacturing apparatus of the invention that is the subject of the present application, utilized to charge a fluid dynamic-pressure bearing device with lubricating fluid, is made up of: a lubricating-fluid tank whose interior is filled partway with lubricating fluid; a vacuum chamber for placing a dynamic-pressure bearing device under a reduced-pressure environment; a nozzle for streaming the lubricating fluid into the bearing device; and a vacuum-evacuation system for evacuating and repressurizing the interior of the lubricating-fluid tank and the interior of the vacuum chamber.
- the pressure of the hollow, fluid-absent portion of the lubricating-fluid tank interior is reduced to eliminate air dissolved into the lubricating fluid.
- the hollow portion is pressure-elevated to apply pressure to the lubricating fluid and force it out the nozzle tip.
- An infusion apparatus of the present invention in another aspect enables the trickle-feeding of lubricating fluid inside the lubricating-fluid tank.
- the shock on and splashes formed in the lubricating fluid when being trickled promote the removal of gas from the lubricating fluid, therefore making possible efficient minimizing of the concentration of dissolved gas present in the lubricating fluid.
- the infusion apparatus is equipped with a stirring mechanism within the lubricating-fluid tank to enable efficient minimizing of the concentration of dissolved gas present in the lubricating fluid.
- valve mechanism for controlling fluid dispensation has only two modes, shutoff and open, and the switching between the two modes is rapid. Inasmuch as the valve mechanism has only two modes, controlling it is rudimentary; thus the fluid delivery quantity may be controlled simply by the length of time that the valve is open.
- the valve shutoff is positioned adjacent the basal portion of the nozzle, such that the amount of room from the location of the shutoff to the nozzle tip is extremely small. Therefore, in the interval from the valve shutoff to where the nozzle tip starts, sites where air bubbles would stay are essentially nonexistent. If there are places where air bubbles form from the shutoff to the tip, when the vacuum chamber is repeatedly pumped down and repressurized, it can happen that spurting of lubricating fluid remaining behind in the nozzle section occurs, contaminating the infusion apparatus and the dynamic-pressure bearing device.
- utilizing the valve mechanism according to the aspect of the present invention just described enables such counterproductive nuisances to be reduced.
- FIG. 1 is a schematic view of a lubricating-fluid infusion apparatus involving the present invention
- FIG. 2 is schematic views of an dispensing device and a fluid tank
- FIG. 3 is magnified views of key portions of the dispensing device
- FIG. 4 is a diagram for explaining how the lubricating-fluid infusion apparatus operates
- FIG. 5 is an enlarged view of the seal section of a dynamic-pressure bearing device
- FIG. 6 is a second view of a dynamic-pressure bearing device seal section
- FIG. 7 is a diagram for explaining a procedure to check for air encroachment
- FIG. 8 is a diagram for explaining a lubricating-fluid degassing procedure
- FIG. 9 is a diagram for explaining a procedure to trickle-feed lubricating fluid into the fluid tank.
- FIG. 10 is views of spindle motors fit out with fluid dynamic-pressure bearings.
- FIG. 1 illustrates a lubricating-fluid infusion apparatus 1 for implementing a lubricating-fluid infusion method involving the present invention.
- the lubricating-fluid infusion apparatus 1 is made up of a vacuum chamber 2 , an dispenser 3 , a lubricating fluid tank 4 , and, for pumping down the interior of these components, a vacuum pumping device and a gas-introduction mechanism R, as well as their connecting supply lines.
- a general rotary pump P is employed as the vacuum pumping device.
- the gas-introduction mechanism R comprising a flow control valve W, and a filter F for preventing dust from invading the mechanism, introduces ambient air into the supply lines.
- the flow control valve W adjusted to make it so that the air inflow speed does not grow excessively large.
- Reference marks G 1 and G 2 indicate Penning gauges, which enable the internal pressure of the vacuum chamber 2 and fluid tank 4 to be monitored.
- the dispenser 3 is made up of a valve mechanism 30 (shown in FIG. 3 ) and a cylindrical capillary tube 32 mounted in the tip of the valve mechanism.
- the dispenser 3 is connected to the bottom portion of the fluid tank 4 through a feed duct 42 .
- a dynamic-pressure bearing device 5 is set inside the vacuum chamber 2 , and is infused with lubricating fluid supplied through the tip of the capillary tube 32 .
- the vacuum chamber 2 is of glass manufacture in a lidded cylindrical form that is open-ended along the underside; thus the status within the chamber may be observed from without. As depicted in FIG. 1 , the open-ended portion of the chamber along its underside is closed off by a pedestal 21 . This occlusion is maintained airtight by means of a not-illustrated O-ring made of rubber.
- the vacuum chamber 2 is connected to the rotary pump P and the gas-introduction mechanism R via ventilation valves V and W.
- FIG. 2 illustrates the fluid tank 4 and the dispenser 3 .
- an empty space 45 is left in the upper portion of the reservoir 4 , and by pumping down this space, the concentration of gas dissolved in the lubricating fluid can be lowered.
- a conduit 42 b connected to this region of the reservoir 4 , through which the pressure of the empty space 45 is reduced/elevated.
- a stirring mechanism is operated to promote the reducing of the concentration of gas dissolved into the lubricating fluid.
- the stirring mechanism is made up of a rod 44 furnished with a magnet, and a stirrer 43 likewise furnished with a magnet, wherein rotating the rod 44 rotates the stirrer 43 in the interior of the fluid tank 4 .
- the fluid tank 4 interior is joined to the dispenser 3 via the feed duct 42 , and in turn is joined to the exterior through the capillary tube 32 mounted in the tip of the dispenser 3 .
- FIG. 2A For that purpose, in the FIG. 2A instance, ejection pressure is imparted to the lubricating fluid by introducing air at atmospheric pressure into the empty space 45 .
- FIG. 2B represented in FIG. 2B is a different method, in which ejection pressure is imparted to lubricating fluid stored within a cylinder 46 by placing a plummet 48 onto a plunger 47 fitted into the cylinder 46 .
- An advantage to the FIG. 2B method is that pressure may be imparted to the lubricating fluid without exposing it to air.
- the fluid must be adjusted ahead of time to adequately reduce the concentration of gas dissolved in the fluid. Which of these two methods to choose is best decided by the technician taking other factors into consideration.
- the infusion process can also be carried out on a plurality of dynamic-pressure bearing devices placed within the vacuum chamber 2 .
- lubricating fluid can be infused into a plurality of dynamic-pressure bearing devices with only a one-time evacuation of the vacuum chamber.
- a jig onto which plural bearing devices can be set is necessary, as is installing a mechanism that shifts the jig.
- a jig and a mechanism of this sort may be, to give one example, a jig onto which a number of dynamic-pressure bearing devices can be set, arrayed circumferentially, and a rotating mechanism designed to rotate the jig so as to sequentially shift each bearing device in turn into place directly beneath the cylindrical capillary tube.
- the capillary tube 32 tip is in a situation in which it is exposed to atmospheric pressure. Under those circumstances, external air tries to enter in, heading toward the fluid tank 4 . Conversely, when the infusion apparatus 1 dispenses lubricating fluid, on the one hand the tip of the capillary tube 32 is under reduced pressure; on the other, the empty space 45 is put at atmospheric pressure, imparting dispensing pressure to the lubricating-fluid. Under these circumstances, the lubricating fluid tries to flow out, heading toward the exterior.
- valve mechanism 30 of the structure illustrated in FIG. 3 can be employed as such a valve.
- FIG. 3 a sectional view illustrating key features of the dispenser 3 .
- fluid is dispensed into the dynamic-pressure bearing device.
- an inlet 34 Joined to the fluid tank 4 via the feed duct 42 is an inlet 34 through which lubricating fluid imparted with delivery pressure is supplied.
- a supply hole 35 formed in a valve base part 31 an occluding rod 33 is accommodated for being pressed back and forth by a drive mechanism 38 .
- the occluding rod 33 is pressed downward in the figure by the drive mechanism 38 , it closes off an occlusion hole 37 , forming a shutoff ( FIG. 3A ).
- the drive mechanism 38 can be a device having the lone capability of simply shifting the occluding rod 33 back and forth, and can be constituted from, for example, a spring and an electromagnet. The occluding rod 33 can thus be driven at high speed merely by electrical on/off switching.
- a valve mechanism 30 configured in this way, the occlusion established by the occluding rod 33 and the occlusion hole 37 is located extremely close to the basal end of the capillary tube 32 (nozzle); moreover, forward of the shutoff, there is no surplus cavity in which air bubbles and the like would get stuck.
- the lubricating-fluid flowpath in the dispenser 30 running forward of the occlusion is constituted almost exclusively by the cavity in the interior of the cylindrical capillary tube 32 .
- the vacuum chamber 2 is lifted up into its opened state as indicated in FIG. 4A , and the dynamic-pressure bearing device 5 is set in a predetermined position atop the pedestal 21 .
- a special jig or a precision-movable stage may be employed.
- the inside of the vacuum chamber 2 is at atmospheric pressure whereas the empty space 45 in the fluid tank 4 is continuously evacuated, wherein the space is pumped down to a pressure of 10 Pa (first pressure).
- the stirrer 43 plunged into the fluid tank 4 interior rotates, thus stirring the lubricating fluid. Gastightness between the fluid tank 4 and the vacuum chamber 2 is maintained by the dispenser 3 .
- the concentration of gas present dissolved within the lubricating fluid may be deemed to be at a concentration about in equilibrium with that of the atmosphere of 10 Pa in pressure.
- the vacuum chamber 2 is lowered to close off its open-ended side against the pedestal 21 , and the interior is pumped down.
- the dispenser 3 and the fluid tank 4 are lowered together with the vacuum chamber 2 , shifting to a low position.
- the tip of the capillary tube 32 is positioned into the seal section 53 ( FIG. 5 ) formed in the open portion of the bearing gap of the dynamic-pressure bearing device 5 .
- the fluid tank 4 having shifted downward, the change in relative position of the rod 44 brings its magnetic force out of action, and thus the stirrer 43 stops rotating, halting the stirring action.
- the evacuation level for the vacuum chamber 2 is adjusted (pressure-adjusting step) so that the internal pressure of the vacuum chamber 2 will go to a pressure (second pressure) somewhat higher than the first pressure.
- ambient air is introduced into the empty space 45 , raising it to atmospheric pressure.
- Ambient air is advantageous as the most readily available source for supplying constant pressure. Nevertheless, the space 45 does not necessarily have to be brought to atmospheric pressure, but according to requirements may equally well be brought beneath atmospheric or above atmospheric pressure, freely selected using a suitable device.
- valve mechanism 30 is opened for a predetermined duration to deliver the proper quantity of lubricating fluid that the dynamic-pressure bearing device 5 is meant to retain.
- the lubricating fluid in the fluid tank 4 interior will have been exposed to air at atmospheric pressure, because the stirring will have been stopped, in particular the lubricating fluid being drawn out from the lower portion of the fluid tank 4 will have been in a state of approximate equilibrium with the first pressure.
- the lubricating fluid being ejected flows out from the tip of the capillary tube 32 .
- lubricating fluid flowing out from the tip of the capillary tube 32 will not froth, because the internal pressure of the vacuum chamber 2 will have gone to 30 Pa (second pressure), which is greater than the first pressure. Therefore, the process of wiping up lubricating fluid having splattered due to frothing and become stuck to the dynamic-pressure bearing device can be omitted. What is more, the elimination of loss due to frothing reduces dispensing volume variation, making the dispensing volume more accurate.
- the interior of the vacuum chamber 2 may if necessary be momentarily pumped down to a pressure (fifth pressure) lower than the second pressure.
- the chamber interior may be pumped down to the same 10-Pa level as the first pressure. Doing so makes evacuation of the bearing even more thorough.
- the chamber Prior to fluid dispensing, however, the chamber must be pressurized to a pressure (second pressure) higher than the first pressure to prevent the fluid from frothing.
- FIG. 5 represents an enlarged view of the vicinity of the seal section 53 of the dynamic-pressure bearing device 5 right after having been infused with fluid.
- the seal 53 is formed in the open end of the bearing gap—marked with reference numeral 54 in the figure—in between the shaft 51 and the sleeve 52 .
- the tip of the cylindrical capillary tube 32 is drawn near the seal 53 , to just short of touching its wall surfaces, in which state the lubricating fluid is dispensed.
- the shaft 51 constitutes a bearing-device rotary component
- the sleeve 52 constitutes a bearing-device stationary component.
- Lubricating fluid having been dispensed spreads around the entire the seal section due to its affinity for the seal-section wall surfaces, but does not reach the depths of the bearing gap 54 .
- the lubricating fluid marked with reference numeral 6 in FIG. 5 —need not fill the seal section in its entirety, but must occupy the entire circuit of seal area of the gap.
- the bearing-device environs having been pumped down to 30 Pa beforehand, the bearing gap will have been pumped down to a pressure near that, and thus the lubricating fluid will be in a state in which due to its affinity for the wall surfaces it will readily enter into the depths of the bearing gap.
- the right-hand side of FIG. 5 schematically represents the immediate post-dispensing state of the fluid.
- the lubricating fluid 6 Immediately post-dispensing the lubricating fluid 6 pools in the open portion of the bearing device, but by its affinity for the wall surfaces the fluid transitions at once into the state sketched on the left-hand side of the figure. In the figure left-hand side, the lubricating fluid has in part crept into the depths of the bearing gap 54 , lowering the liquid surface of the lubricating fluid in the seal section 53 by that extent.
- the fluid dispensing job may be divided into two or more cycles.
- the second and subsequent fluid-dispensing operations then can be carried out by estimating the time, following the first-cycle fluid-dispensing job, for the lubricating fluid to spread around the entire seal section 53 and its liquid surface to drop sufficiently.
- the vacuum chamber 2 interior is repressurized (third pressure).
- the repressurization develops a pressure differential between the lubricating fluid 6 interior/exterior, forcing the lubricating fluid 6 into the depths of the bearing gap 54 and completing the lubricating-fluid dispensing job.
- it is easiest to repressurize back to atmospheric pressure repressurization to a pressure lower than atmospheric will not impede the dispensing process, as long as the pressure is sufficient to force the lubricating fluid all the way into the bearing gap.
- the vacuum chamber 2 may again be evacuated and the fluid dispensing process carried out again, once lubricating fluid has been forced into the gap and sufficient space in the seal section 53 has been secured.
- FIG. 6 is an enlarged view of a bearing-device seal section, in this case in a dynamic-pressure bearing device 5 ′ in which the upper-end face of the sleeve has a slope 60 .
- a fluid-repellent film is formed on the slope and shaft surfaces.
- the dispensed lubricating fluid fills over the slope (right half of the figure), and by capillary action subsequently permeates its way into the bearing gap (left half of the figure).
- Benefits of having the slope 60 are not only that a large volume of lubricating fluid may be dispensed at once, but also that lubricating fluid does not get left behind on the upper-end face of the sleeve.
- the dynamic-pressure bearing device 5 on which the dispensing procedure has been finished is then run through a procedure to check for the presence of air encroachment.
- the reliability of the bearing-device infusion method of present invention is extraordinarily high, foul dispensings can arise nevertheless. Thus, inspection for excluding such rejects is carried out.
- FIG. 7 is a diagram for explaining this procedure.
- the dispensing-processed bearing device 5 is put under atmospheric pressure.
- the pressure environment for this procedure is concerned, as long as the pressure is higher than a later-described fourth pressure, inspection is in principle possible, but atmospheric pressure, being quite readily realized, is advantageous.
- the dynamic-pressure bearing device 5 is set inside a vacuum case 91 furnished with an evacuation mechanism, and anchored using a suitable jig. In that situation, the level of the lubricating fluid in a state in which atmospheric pressure has been applied is measured. The measurement is made using a laser displacement sensor 93 , whose beam passes through a glass lid 92 on the vacuum case 91 .
- a vacuum pump P and a venting valve are operated to lower the internal pressure of the vacuum case 91 to 1000 Pa, which is the fourth pressure.
- the fluid level is once again measured, and is compared with the level before the pressure was reduced. If upon this second measurement the amount by which the level has risen exceeds a predetermined value, the device is excluded as a reject; if not, the device is rendered an acceptable item.
- the aircraft When the dynamic-pressure bearing device is shipped by airfreight, the aircraft will fly in the lower regions of the stratosphere, which at maximum elevation is in the neighborhood of 14 km into the sky. At that elevation the atmospheric pressure is on the order of 1 40 hPa, which is considerably larger than 1000 Pa (10 hPa). Consequently, if a dynamic-pressure bearing device has passed the reduced-pressure test at 1000 Pa, then even if the device is transported in a cargo bay that is not pressurized in the least, the likelihood of fluid leakage occurring may be deemed to be extremely small.
- the lubricating fluid that is fed into the lubricating-fluid infusion apparatus 1 is subjected to a special degassing process in advance, which shortens the time required for the degassing process within the fluid tank 4 .
- lubricating fluid that is insufficiently degassed because the interior of the fluid tank 4 is repeatedly exposed to the air may be deaerated with greater assurance in a separate vacuum chamber initially.
- FIG. 8 illustrates the configuration of a degassing device utilized for such objectives.
- a vacuum case 9 is placed atop a magnetic-stirrer drive mechanism 8 , and within a lubricating-fluid reservoir 7 inside the case 9 lubricating fluid 6 is contained.
- the vacuum case 9 interior is pumped down by a vacuum pump P to a pressure lower than the first pressure.
- a good target is pumping down to 10 Pa or less to keep on evacuating the case further. Long-term stirring in that state is continued, reducing dissolved gas until the level at which it is in equilibrium with this pressure ambient.
- FIG. 9 represents a method of trickle feeding lubricating fluid into the fluid tank 4 .
- the lubricating fluid is fed into a funnel 100 , and via a microflow valve 101 is trickled in drops into the fluid tank 4 .
- the fluid tank 4 interior is pumped down to 10 Pa or so. With the surface area per unit volume of the drops being large, degassing proceeds rapidly. And degassing is promoted further by the drops undergoing shock when they strike the inner surface of the fluid tank and the liquid surface.
- Not-illustrated heaters are attached to the vacuum case 9 and the fluid tank 4 utilized for the preprocess degassing.
- the lubricating fluid is deaerated having been heated up by the heaters to 60 degrees. Degassing proceeds swiftly because in general the solubility of gasses in a liquid drops as the temperature of the liquid rises.
Abstract
Description
- 1. Technical Field
- The present invention relates to lubricating-fluid infusion apparatuses for dispensing lubricating fluid into dynamic-pressure bearing devices employed in signal record/playback devices such as hard-disk drives.
- 2. Description of the Related Art
- (1) Dynamic-Pressure Bearing Device Structures
- A variety of fluid dynamic-pressure bearings have to date been employed in spindle motors used in signal record/playback devices such as hard-disk drives. Fluid dynamic-pressure bearings provide journal support by producing fluid pressure in a lubricant, such as a lubricating fluid, interposed in between a shaft and sleeve.
- Single examples of spindle motors that employ a dynamic-pressure bearing of this sort are illustrated in
FIGS. 10A and 10B . - The spindle motor in
FIG. 10A is fit out with a dynamic-pressure bearingdevice 50, in which a lubricating-fluidtaper seal section 53 is formed, in a single location only. The motor'sshaft 51 is inserted into asleeve 52, wherein radial dynamic-pressure bearings shaft 51 at its tip is athrust plate 56 wherethrust bearings sleeve 52 is closed off by a thrust bushing 57, wherein the bearing gap extending from the lubricating-fluid boundary surface in thetaper seal section 53 to the shaft tip is filled with the lubricating fluid, without any places in which the fluid is interrupted. The open portion of the bearing device, where the bearing gap meets the external air, is in the upper end only, and is where thetaper seal section 53 is formed. - A bearing-device structure of this sort is highly reliable in that the surface area of contact between the lubricating fluid and the external air is small, and thus neither the mixing of air bubbles into, nor the gasification of, the lubricating fluid is liable to occur. Nonetheless, in order to inject lubricating fluid into the bearing device, air must be discharged ahead of time from the bearing gap, making equipment for that purpose necessary.
- The spindle motor in
FIG. 10B is fit out with a dynamic-pressure bearingdevice 5′, in which the open portions of the bearing gap are in two locations, above and below, which puts thetaper seal sections - As far as the injection of lubricating fluid into the bearing device is concerned, if for example lubricating fluid is poured into the taper seal section in the upper end, it spreads along by capillary action, heading downward through the successive gap sections, and the air is discharged through the lower end. But the complex bearing-gap conformation means that there will be slight inconsistencies in the gap sections that give rise to differences in how the lubricating fluid spreads, leading to unequal permeation. Consequently, with this structure as well, it is necessary to discharge air ahead of time from the bearing gap.
- In the final analysis, as long as a dynamic-pressure bearing device is not especially structured for readily discharging air from its bearing gap, when the device is to be charged with lubricating fluid, it will be necessary to exhaust the bearing gap.
- (2) Publicly Known Infusing Methods and Problems Therewith
- Methods such as follows are examples of techniques for injecting lubricating fluid into the bearing gap, after air filling the gap has been discharged, in dynamic-pressure bearing devices like
device - (2-1) First Method
- One is a method in which the bearing device and a container filled with lubricating fluid are put into a vacuum chamber, and with the chamber in an evacuated state, the open portion of the bearing gap is either immersed in lubricating fluid or is submerged within lubricating fluid, after which air is introduced into the vacuum chamber to repressurize it. The air pressure applied in repressurization forces the lubricating fluid soundly into the full depth of the bearing gap.
- Although this method may be realized with relatively simple facilities, the lubricating fluid sticks to the outside of the bearing device. Particularly in implementations in which the bearing device is incorporated into a hard disk drive, lubricating fluid having adhered to the outside of the bearing device becomes a cause of fluid contaminating the disk(s). The adhered lubricating fluid therefore must be carefully wiped off, which makes necessary a manufacturing process step that significantly impairs productivity. In implementations in which a screw-hole into which a disk clamp is fastened is provided in the head of the shaft, the lubricating fluid permeates the screw-hole and the thread groove. Removing lubricating fluid that has permeated a narrow area of this sort in the bearing device is extremely difficult.
- (2-2) Second Method
- An alternative technique is a method in which the bearing device is set inside a vacuum chamber, and with the chamber in an evacuated state a cylindrical capillary tube such as a fine syringe needle is used to trickle lubricating fluid into the open portion, or the taper seal section, of the bearing device, following which the chamber is repressurized.
- Employing this method might lead to the expectation that the process step for wiping away lubricating fluid that has stuck to the outer side of the bearing device could be omitted, but in actuality the method does not necessarily work well. This is because when the lubricating fluid is squirted from the needle tip, frequently the fluid froths at the tip and the froth bursts, splattering on and contaminating the outside of the bearing device.
- It might then seem that a way to get rid of the frothing would be beforehand to sufficiently clear the lubricating fluid of air that has dissolved into it. In practice, however, frothing occurs even if the lubricating fluid undergoes a degassing process, such that contamination of the bearing device exterior is eliminated only with difficulty.
- A manufacturing apparatus of the invention that is the subject of the present application, utilized to charge a fluid dynamic-pressure bearing device with lubricating fluid, is made up of: a lubricating-fluid tank whose interior is filled partway with lubricating fluid; a vacuum chamber for placing a dynamic-pressure bearing device under a reduced-pressure environment; a nozzle for streaming the lubricating fluid into the bearing device; and a vacuum-evacuation system for evacuating and repressurizing the interior of the lubricating-fluid tank and the interior of the vacuum chamber.
- In this infusion apparatus, the pressure of the hollow, fluid-absent portion of the lubricating-fluid tank interior is reduced to eliminate air dissolved into the lubricating fluid. In turn, the hollow portion is pressure-elevated to apply pressure to the lubricating fluid and force it out the nozzle tip. What this means is that both the function of a degassing vessel for carrying out a deaerating process on the lubricating fluid, and of a pressurizing chamber for developing pressure in the lubricating fluid to force it out are realized by means of a single vacuum chamber. Moreover, because the internal pressure of the vacuum chamber in which fluid infusion is carried out can be controlled at will, frothing of the lubricating fluid when it is being dispensed can be held in check.
- An infusion apparatus of the present invention in another aspect enables the trickle-feeding of lubricating fluid inside the lubricating-fluid tank. The shock on and splashes formed in the lubricating fluid when being trickled promote the removal of gas from the lubricating fluid, therefore making possible efficient minimizing of the concentration of dissolved gas present in the lubricating fluid.
- In another inventive aspect the infusion apparatus is equipped with a stirring mechanism within the lubricating-fluid tank to enable efficient minimizing of the concentration of dissolved gas present in the lubricating fluid.
- Another feature of an infusion apparatus of the present invention is that its valve mechanism for controlling fluid dispensation has only two modes, shutoff and open, and the switching between the two modes is rapid. Inasmuch as the valve mechanism has only two modes, controlling it is rudimentary; thus the fluid delivery quantity may be controlled simply by the length of time that the valve is open.
- In this infusion apparatus, the valve shutoff is positioned adjacent the basal portion of the nozzle, such that the amount of room from the location of the shutoff to the nozzle tip is extremely small. Therefore, in the interval from the valve shutoff to where the nozzle tip starts, sites where air bubbles would stay are essentially nonexistent. If there are places where air bubbles form from the shutoff to the tip, when the vacuum chamber is repeatedly pumped down and repressurized, it can happen that spurting of lubricating fluid remaining behind in the nozzle section occurs, contaminating the infusion apparatus and the dynamic-pressure bearing device. However, utilizing the valve mechanism according to the aspect of the present invention just described enables such counterproductive nuisances to be reduced.
- From the following detailed description in conjunction with the accompanying drawings, the foregoing and other objects, features, aspects and advantages of the present invention will become readily apparent to those skilled in the art.
-
FIG. 1 is a schematic view of a lubricating-fluid infusion apparatus involving the present invention; -
FIG. 2 is schematic views of an dispensing device and a fluid tank; -
FIG. 3 is magnified views of key portions of the dispensing device; -
FIG. 4 is a diagram for explaining how the lubricating-fluid infusion apparatus operates; -
FIG. 5 is an enlarged view of the seal section of a dynamic-pressure bearing device; -
FIG. 6 is a second view of a dynamic-pressure bearing device seal section; -
FIG. 7 is a diagram for explaining a procedure to check for air encroachment; -
FIG. 8 is a diagram for explaining a lubricating-fluid degassing procedure; -
FIG. 9 is a diagram for explaining a procedure to trickle-feed lubricating fluid into the fluid tank; and -
FIG. 10 is views of spindle motors fit out with fluid dynamic-pressure bearings. - (1) Lubricating-Fluid Infusion Apparatus
- (1-1) Device Overall
- Reference is made to
FIG. 1 , which illustrates a lubricating-fluid infusion apparatus 1 for implementing a lubricating-fluid infusion method involving the present invention. The lubricating-fluid infusion apparatus 1 is made up of avacuum chamber 2, andispenser 3, a lubricatingfluid tank 4, and, for pumping down the interior of these components, a vacuum pumping device and a gas-introduction mechanism R, as well as their connecting supply lines. - In this implementation, a general rotary pump P is employed as the vacuum pumping device. The gas-introduction mechanism R, comprising a flow control valve W, and a filter F for preventing dust from invading the mechanism, introduces ambient air into the supply lines. To further ensure that invasion of dust is prevented, the flow control valve W adjusted to make it so that the air inflow speed does not grow excessively large. Reference marks G1 and G2 indicate Penning gauges, which enable the internal pressure of the
vacuum chamber 2 andfluid tank 4 to be monitored. - The
dispenser 3 is made up of a valve mechanism 30 (shown inFIG. 3 ) and a cylindricalcapillary tube 32 mounted in the tip of the valve mechanism. Thedispenser 3 is connected to the bottom portion of thefluid tank 4 through afeed duct 42. A dynamic-pressure bearing device 5 is set inside thevacuum chamber 2, and is infused with lubricating fluid supplied through the tip of thecapillary tube 32. - The
vacuum chamber 2 is of glass manufacture in a lidded cylindrical form that is open-ended along the underside; thus the status within the chamber may be observed from without. As depicted inFIG. 1 , the open-ended portion of the chamber along its underside is closed off by apedestal 21. This occlusion is maintained airtight by means of a not-illustrated O-ring made of rubber. Thevacuum chamber 2 is connected to the rotary pump P and the gas-introduction mechanism R via ventilation valves V and W. -
FIG. 2 illustrates thefluid tank 4 and thedispenser 3. As depicted inFIG. 2A , anempty space 45 is left in the upper portion of thereservoir 4, and by pumping down this space, the concentration of gas dissolved in the lubricating fluid can be lowered. Relevant to that operation is aconduit 42 b connected to this region of thereservoir 4, through which the pressure of theempty space 45 is reduced/elevated. During pump-down, a stirring mechanism is operated to promote the reducing of the concentration of gas dissolved into the lubricating fluid. The stirring mechanism is made up of arod 44 furnished with a magnet, and astirrer 43 likewise furnished with a magnet, wherein rotating therod 44 rotates thestirrer 43 in the interior of thefluid tank 4. Thefluid tank 4 interior is joined to thedispenser 3 via thefeed duct 42, and in turn is joined to the exterior through thecapillary tube 32 mounted in the tip of thedispenser 3. - In order to dispense lubricating fluid into the dynamic-pressure bearing device, a sufficiently large, stabilized ejection pressure must be attendant on the lubricating fluid sent into the
dispenser 3. Otherwise, the fluid-dispensing volume will vary with each dispensing operation, which is prohibitive of assuring uniform product quality, especially in cases in which bearing devices are mass-produced. - For that purpose, in the
FIG. 2A instance, ejection pressure is imparted to the lubricating fluid by introducing air at atmospheric pressure into theempty space 45. Meanwhile, represented inFIG. 2B is a different method, in which ejection pressure is imparted to lubricating fluid stored within acylinder 46 by placing aplummet 48 onto aplunger 47 fitted into thecylinder 46. An advantage to theFIG. 2B method is that pressure may be imparted to the lubricating fluid without exposing it to air. However, because the lubricating fluid once having been fed into thefluid tank 4 can no longer be degassed, the fluid must be adjusted ahead of time to adequately reduce the concentration of gas dissolved in the fluid. Which of these two methods to choose is best decided by the technician taking other factors into consideration. - It will be appreciated that the infusion process can also be carried out on a plurality of dynamic-pressure bearing devices placed within the
vacuum chamber 2. By sequentially shifting into place and performing the infusion process on the dynamic-pressure bearing devices, lubricating fluid can be infused into a plurality of dynamic-pressure bearing devices with only a one-time evacuation of the vacuum chamber. In order to execute this procedure, however, within the vacuum chamber 2 a jig onto which plural bearing devices can be set is necessary, as is installing a mechanism that shifts the jig. A jig and a mechanism of this sort may be, to give one example, a jig onto which a number of dynamic-pressure bearing devices can be set, arrayed circumferentially, and a rotating mechanism designed to rotate the jig so as to sequentially shift each bearing device in turn into place directly beneath the cylindrical capillary tube. - (1-2) Valve Mechanism
- As will be detailed later, in the lubricating-fluid infusion apparatus 1, with the interior of the
fluid tank 4 in a reduced-pressure state in order to degas the lubricating fluid, thecapillary tube 32 tip is in a situation in which it is exposed to atmospheric pressure. Under those circumstances, external air tries to enter in, heading toward thefluid tank 4. Conversely, when the infusion apparatus 1 dispenses lubricating fluid, on the one hand the tip of thecapillary tube 32 is under reduced pressure; on the other, theempty space 45 is put at atmospheric pressure, imparting dispensing pressure to the lubricating-fluid. Under these circumstances, the lubricating fluid tries to flow out, heading toward the exterior. In either case, the flow has to be stopped with the valve mechanism. Consequently, what is sought in a valve mechanism for thedispenser 3 is that the valve will not give rise to leaking not only when the internal pressure is in a higher state, but also when the external pressure is. Avalve mechanism 30 of the structure illustrated inFIG. 3 can be employed as such a valve. - The description now turns to
FIG. 3 , a sectional view illustrating key features of thedispenser 3. From the end portion of the cylindricalcapillary tube 32, mounted in the tip of thedispenser 3, fluid is dispensed into the dynamic-pressure bearing device. Joined to thefluid tank 4 via thefeed duct 42 is aninlet 34 through which lubricating fluid imparted with delivery pressure is supplied. In asupply hole 35 formed in avalve base part 31, an occludingrod 33 is accommodated for being pressed back and forth by adrive mechanism 38. When the occludingrod 33 is pressed downward in the figure by thedrive mechanism 38, it closes off anocclusion hole 37, forming a shutoff (FIG. 3A ). Conversely, when the rod is drawn upward in the figure, theocclusion hole 37 is cleared, permitting the passage of lubricating fluid (FIG. 3B ). Thedrive mechanism 38 can be a device having the lone capability of simply shifting the occludingrod 33 back and forth, and can be constituted from, for example, a spring and an electromagnet. The occludingrod 33 can thus be driven at high speed merely by electrical on/off switching. - In a
valve mechanism 30 configured in this way, the occlusion established by the occludingrod 33 and theocclusion hole 37 is located extremely close to the basal end of the capillary tube 32 (nozzle); moreover, forward of the shutoff, there is no surplus cavity in which air bubbles and the like would get stuck. The lubricating-fluid flowpath in thedispenser 30 running forward of the occlusion is constituted almost exclusively by the cavity in the interior of the cylindricalcapillary tube 32. - (2) Infusion Procedure
- (2-1) Infusion Process
- Initially the
vacuum chamber 2 is lifted up into its opened state as indicated inFIG. 4A , and the dynamic-pressure bearing device 5 is set in a predetermined position atop thepedestal 21. To heighten the accuracy with which the bearing device is located into place, a special jig or a precision-movable stage may be employed. - In this state, the inside of the
vacuum chamber 2 is at atmospheric pressure whereas theempty space 45 in thefluid tank 4 is continuously evacuated, wherein the space is pumped down to a pressure of 10 Pa (first pressure). At the same time, by the magnet-equippedrod 44 rotating, thestirrer 43 plunged into thefluid tank 4 interior rotates, thus stirring the lubricating fluid. Gastightness between thefluid tank 4 and thevacuum chamber 2 is maintained by thedispenser 3. With the lubricating fluid being exposed to an atmosphere of 10 Pa in pressure, the evacuation and stirring are continued. Under such conditions, the concentration of gas present dissolved within the lubricating fluid may be deemed to be at a concentration about in equilibrium with that of the atmosphere of 10 Pa in pressure. - Next the
vacuum chamber 2 is lowered to close off its open-ended side against thepedestal 21, and the interior is pumped down. Thedispenser 3 and thefluid tank 4 are lowered together with thevacuum chamber 2, shifting to a low position. As a result, the tip of thecapillary tube 32 is positioned into the seal section 53 (FIG. 5 ) formed in the open portion of the bearing gap of the dynamic-pressure bearing device 5. At the same time, as a result of thefluid tank 4 having shifted downward, the change in relative position of therod 44 brings its magnetic force out of action, and thus thestirrer 43 stops rotating, halting the stirring action. - Then the evacuation level for the
vacuum chamber 2 is adjusted (pressure-adjusting step) so that the internal pressure of thevacuum chamber 2 will go to a pressure (second pressure) somewhat higher than the first pressure. - After that, in order to impart delivery pressure to the lubricating fluid, ambient air is introduced into the
empty space 45, raising it to atmospheric pressure. Ambient air is advantageous as the most readily available source for supplying constant pressure. Nevertheless, thespace 45 does not necessarily have to be brought to atmospheric pressure, but according to requirements may equally well be brought beneath atmospheric or above atmospheric pressure, freely selected using a suitable device. - Next, the
valve mechanism 30 is opened for a predetermined duration to deliver the proper quantity of lubricating fluid that the dynamic-pressure bearing device 5 is meant to retain. At that time, although the lubricating fluid in thefluid tank 4 interior will have been exposed to air at atmospheric pressure, because the stirring will have been stopped, in particular the lubricating fluid being drawn out from the lower portion of thefluid tank 4 will have been in a state of approximate equilibrium with the first pressure. - The lubricating fluid being ejected flows out from the tip of the
capillary tube 32. At that point, lubricating fluid flowing out from the tip of thecapillary tube 32 will not froth, because the internal pressure of thevacuum chamber 2 will have gone to 30 Pa (second pressure), which is greater than the first pressure. Therefore, the process of wiping up lubricating fluid having splattered due to frothing and become stuck to the dynamic-pressure bearing device can be omitted. What is more, the elimination of loss due to frothing reduces dispensing volume variation, making the dispensing volume more accurate. - It should be noted that in advance of the pressure-adjusting step, the interior of the
vacuum chamber 2 may if necessary be momentarily pumped down to a pressure (fifth pressure) lower than the second pressure. For example, the chamber interior may be pumped down to the same 10-Pa level as the first pressure. Doing so makes evacuation of the bearing even more thorough. Prior to fluid dispensing, however, the chamber must be pressurized to a pressure (second pressure) higher than the first pressure to prevent the fluid from frothing. - (2-2) Status of Seal Section
-
FIG. 5 represents an enlarged view of the vicinity of theseal section 53 of the dynamic-pressure bearing device 5 right after having been infused with fluid. - The
seal 53 is formed in the open end of the bearing gap—marked withreference numeral 54 in the figure—in between theshaft 51 and thesleeve 52. The tip of the cylindricalcapillary tube 32 is drawn near theseal 53, to just short of touching its wall surfaces, in which state the lubricating fluid is dispensed. Theshaft 51 constitutes a bearing-device rotary component, and thesleeve 52 constitutes a bearing-device stationary component. With theseal section 53 being formed in the open portion of the bearing gap, it surrounds the rotary component. - Lubricating fluid having been dispensed spreads around the entire the seal section due to its affinity for the seal-section wall surfaces, but does not reach the depths of the
bearing gap 54. At this stage the lubricating fluid—marked withreference numeral 6 inFIG. 5 —need not fill the seal section in its entirety, but must occupy the entire circuit of seal area of the gap. Moreover, by the bearing-device environs having been pumped down to 30 Pa beforehand, the bearing gap will have been pumped down to a pressure near that, and thus the lubricating fluid will be in a state in which due to its affinity for the wall surfaces it will readily enter into the depths of the bearing gap. The right-hand side ofFIG. 5 schematically represents the immediate post-dispensing state of the fluid. Immediately post-dispensing the lubricating fluid 6 pools in the open portion of the bearing device, but by its affinity for the wall surfaces the fluid transitions at once into the state sketched on the left-hand side of the figure. In the figure left-hand side, the lubricating fluid has in part crept into the depths of thebearing gap 54, lowering the liquid surface of the lubricating fluid in theseal section 53 by that extent. - Depending on the configuration of the
seal section 53, and on the quantity of lubricating fluid that the bearing is meant to hold, in some cases the requisite amount of lubricating fluid cannot be dispensed in a one-time operation. In such cases, the fluid dispensing job may be divided into two or more cycles. The second and subsequent fluid-dispensing operations then can be carried out by estimating the time, following the first-cycle fluid-dispensing job, for the lubricating fluid to spread around theentire seal section 53 and its liquid surface to drop sufficiently. - After the fluid dispensing operation is finished, the
vacuum chamber 2 interior is repressurized (third pressure). The repressurization develops a pressure differential between the lubricating fluid 6 interior/exterior, forcing the lubricatingfluid 6 into the depths of thebearing gap 54 and completing the lubricating-fluid dispensing job. Although it is easiest to repressurize back to atmospheric pressure, repressurization to a pressure lower than atmospheric will not impede the dispensing process, as long as the pressure is sufficient to force the lubricating fluid all the way into the bearing gap. In addition, thevacuum chamber 2 may again be evacuated and the fluid dispensing process carried out again, once lubricating fluid has been forced into the gap and sufficient space in theseal section 53 has been secured. - Reference is now made to
FIG. 6 , which, likeFIG. 5 , is an enlarged view of a bearing-device seal section, in this case in a dynamic-pressure bearing device 5′ in which the upper-end face of the sleeve has aslope 60. A fluid-repellent film is formed on the slope and shaft surfaces. In implementations in which the dynamic-pressure bearing device is structured in this way, the dispensed lubricating fluid fills over the slope (right half of the figure), and by capillary action subsequently permeates its way into the bearing gap (left half of the figure). Benefits of having theslope 60 are not only that a large volume of lubricating fluid may be dispensed at once, but also that lubricating fluid does not get left behind on the upper-end face of the sleeve. - (2-3) Encroached Air Check
- The dynamic-
pressure bearing device 5 on which the dispensing procedure has been finished is then run through a procedure to check for the presence of air encroachment. Although the reliability of the bearing-device infusion method of present invention is extraordinarily high, foul dispensings can arise nevertheless. Thus, inspection for excluding such rejects is carried out. -
FIG. 7 is a diagram for explaining this procedure. The dispensing-processedbearing device 5 is put under atmospheric pressure. As far as the pressure environment for this procedure is concerned, as long as the pressure is higher than a later-described fourth pressure, inspection is in principle possible, but atmospheric pressure, being quite readily realized, is advantageous. - The dynamic-
pressure bearing device 5 is set inside avacuum case 91 furnished with an evacuation mechanism, and anchored using a suitable jig. In that situation, the level of the lubricating fluid in a state in which atmospheric pressure has been applied is measured. The measurement is made using alaser displacement sensor 93, whose beam passes through aglass lid 92 on thevacuum case 91. - Next a vacuum pump P and a venting valve are operated to lower the internal pressure of the
vacuum case 91 to 1000 Pa, which is the fourth pressure. In this state, the fluid level is once again measured, and is compared with the level before the pressure was reduced. If upon this second measurement the amount by which the level has risen exceeds a predetermined value, the device is excluded as a reject; if not, the device is rendered an acceptable item. - When the dynamic-pressure bearing device is shipped by airfreight, the aircraft will fly in the lower regions of the stratosphere, which at maximum elevation is in the neighborhood of 14 km into the sky. At that elevation the atmospheric pressure is on the order of 1 40 hPa, which is considerably larger than 1000 Pa (10 hPa). Consequently, if a dynamic-pressure bearing device has passed the reduced-pressure test at 1000 Pa, then even if the device is transported in a cargo bay that is not pressurized in the least, the likelihood of fluid leakage occurring may be deemed to be extremely small.
- (2-4) Preprocess Lubricating-Fluid Degassing and Feeding into the Infusion Apparatus
- The lubricating fluid that is fed into the lubricating-fluid infusion apparatus 1 is subjected to a special degassing process in advance, which shortens the time required for the degassing process within the
fluid tank 4. In an infusion method of the present invention, lubricating fluid that is insufficiently degassed because the interior of thefluid tank 4 is repeatedly exposed to the air may be deaerated with greater assurance in a separate vacuum chamber initially. -
FIG. 8 illustrates the configuration of a degassing device utilized for such objectives. Avacuum case 9 is placed atop a magnetic-stirrer drive mechanism 8, and within a lubricating-fluid reservoir 7 inside thecase 9lubricating fluid 6 is contained. - The
vacuum case 9 interior is pumped down by a vacuum pump P to a pressure lower than the first pressure. A good target is pumping down to 10 Pa or less to keep on evacuating the case further. Long-term stirring in that state is continued, reducing dissolved gas until the level at which it is in equilibrium with this pressure ambient. - In addition to the advance degassing process, means may be devised so as to produce a deaerating effect when the lubricating fluid is fed into the
fluid tank 4.FIG. 9 represents a method of trickle feeding lubricating fluid into thefluid tank 4. - Specifically, the lubricating fluid is fed into a
funnel 100, and via amicroflow valve 101 is trickled in drops into thefluid tank 4. Thefluid tank 4 interior is pumped down to 10 Pa or so. With the surface area per unit volume of the drops being large, degassing proceeds rapidly. And degassing is promoted further by the drops undergoing shock when they strike the inner surface of the fluid tank and the liquid surface. - Not-illustrated heaters are attached to the
vacuum case 9 and thefluid tank 4 utilized for the preprocess degassing. The lubricating fluid is deaerated having been heated up by the heaters to 60 degrees. Degassing proceeds swiftly because in general the solubility of gasses in a liquid drops as the temperature of the liquid rises. - The best mode, explained in the foregoing, for embodying the present invention is not limited by the content set forth herein. For example, as the dynamic-pressure bearing device into which lubricating fluid is dispensed, a shaft-rotating type has been depicted, but the effects of the present invention when applied to a shaft-stationary type of dynamic-pressure bearing device do not alter. As a lubricating-fluid stirring mechanism, an example that employs a magnetic stirrer has been illustrated, but rotating the stirrer by utilizing a terminal or other device that introduces rotation into the vacuum chamber yields similar effects.
Claims (20)
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US10/906,495 Abandoned US20050183906A1 (en) | 2004-02-23 | 2005-02-23 | Lubricating-Fluid Infusion Apparatus |
US10/906,494 Active 2025-08-22 US7182106B2 (en) | 2004-02-23 | 2005-02-23 | Fluid dispensation method |
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US8643230B2 (en) | 2009-05-14 | 2014-02-04 | Sinfonia Technology Co., Ltd. | Linear actuator and method of manufacturing linear actuator including a deaerating step |
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CN107477339A (en) * | 2017-08-11 | 2017-12-15 | 嘉兴晟友机械科技有限公司 | The oiling structure of oil sealing inner ring in a kind of oil sealing oiling device |
CN109084155A (en) * | 2018-09-06 | 2018-12-25 | 浙江汇隆新材料股份有限公司 | Oil storage type automatic fuelling device |
US20220074451A1 (en) * | 2020-09-08 | 2022-03-10 | Aktiebolaget Skf | System for lubricating a sealed bearing and associated method |
US11703183B2 (en) * | 2020-09-08 | 2023-07-18 | Aktiebolaget Skf | System for lubricating a sealed bearing and associated method |
Also Published As
Publication number | Publication date |
---|---|
CN100335807C (en) | 2007-09-05 |
US20050184085A1 (en) | 2005-08-25 |
US7168463B2 (en) | 2007-01-30 |
CN100376815C (en) | 2008-03-26 |
CN1661250A (en) | 2005-08-31 |
CN1661249A (en) | 2005-08-31 |
CN1661248A (en) | 2005-08-31 |
US7182106B2 (en) | 2007-02-27 |
CN100365300C (en) | 2008-01-30 |
US20050186101A1 (en) | 2005-08-25 |
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