EP1734260A2 - Silencer for pneumatic drive - Google Patents

Abstract

The muffler has a casing body (2) linked with an exhaust port of a control valve. The body exhibits a porous, air-permeable base structure and includes a cavity. The casing body has a pressure sensor (6), pressure sensor that produces warning signal and switches off pneumatic drive when impact pressure within cavity increased due to increased contamination of muffler reaches a predetermined limit pressure.

Description

The invention relates to a silencer for damping the exiting at pneumatic control valves of a pneumatic actuator sound pressure, consisting of a box-like body which is coupled to the vent port of the control valve, wherein the body has a porous, air-permeable basic structure and includes a cavity.

For pneumatic actuators in the form of double-acting pneumatic cylinders, pneumatic control valves are used to control them. Such double-acting pneumatic cylinders are characterized in that they can be activated in both directions of movement. For this purpose, a piston is provided in the cylinder tube of the pneumatic cylinder, from which a piston rod is guided in the axial direction outward from the cylinder tube. This piston divides the cylinder tube into two pressure chambers, so that when the pressure chambers are alternately pressurized the piston is displaced in one or the other direction.

It is known to apply by appropriate control valves via a pressure line, first, the first pressure chamber with pressure and at the same time the second pressure chamber via the pressure line to vent. This vent is also switched by the control valve. If now the pneumatic cylinder or its piston to move in the opposite direction, the control valve is reversed and the second pressure line of the second pressure chamber pressurized, while the pressure line of the first pressure chamber for venting the first pressure chamber is "unlocked". Since this reversal takes place abruptly and thus abruptly degrades the pressure to be released in the respective pressure line, this is always connected by the sudden pressure reduction with a higher noise level. In this case, a vent port is provided on the control valve for each pressure line, to which the respective pressure line is switched when their "activation". To dampen the noise level, it is known to provide these exhaust ports with mufflers to achieve quieter operation of the pneumatic actuator.

Such mufflers usually have a box-like body, which is connected to the vent port. In this case, this body may for example be provided with a connection thread and screwed directly into the vent port. In order to dampen the pressure reduction and at the same time oppose the flow of air flowing from the pressure chamber to be vented as low as possible flow resistance, the body has a porous and air-permeable basic structure, which usually includes a cavity. Thus, when releasing the pressure line of the air pressure located therein via the vent port and the silencer be degraded, with a sound attenuation is effected.

It has now been found that during prolonged operation of such a pneumatic drive such mufflers are added in particular from the inside by contamination. Since this clogging occurs essentially from the cavity, this is barely visible to the outside. With increasing degree of contamination thus the air permeability of the muffler is reduced, so that always builds up in the muffler when venting an ever-increasing backpressure. By this counter-pressure, however, the movement speed of the pneumatic cylinder is considerably reduced. As a rule, this results in the operator increasing the operating pressure for operating the pneumatic cylinder in order to be able to maintain or restore the desired working speed of the pneumatic cylinder. In order to perform a Drukkerhöhung, it is therefore necessary to size the air compressor larger in order to maintain just this operating speed can. This is on the one hand constructively related to the compressor with higher costs and on the other hand with higher operating costs, since this compressor must produce a higher operating pressure.

Only when the operating pressure can not be increased, so the silencer is changed. Only after changing the muffler can then be used again with the original, lower operating pressure.

The invention is accordingly based on the object to design a muffler of the generic type such that at least from the outside easily recognizable, at which time this muffler is added by pollution and must be replaced.

The object is achieved in that the body is provided with a pressure sensor which causes a warning signal and / or a shutdown of the pneumatic actuator causes with increasing contamination of the muffler and the concomitant increase in back pressure within the cavity at a predeterminable pressure limit.

The embodiment according to the invention provides a silencer, in which it can be seen in the simplest manner when it is to be exchanged or cleaned. For this purpose, a pressure sensor is provided, which causes a warning signal with increasing contamination at a predeterminable limit pressure. This warning signal can be optical, acoustic or otherwise. By this recognizability of the state of the muffler, the operator can replace it early and / or clean, so that you do not have to work with increased operating pressures. Furthermore, it can also be provided that the pneumatic drive is switched off.

In a simple embodiment, the pressure sensor according to claim 2 may consist of a, arranged in a housing pressure piston, which is deflected when the limit pressure is exceeded. In this case, this pressure piston is coupled to a signal pin, which is pressed visibly out of the housing upon deflection of the pressure piston. In this simple embodiment can thus the operator in the simplest way to detect an inadmissible degree of contamination or an inadmissible pressure increase in the cavity formed by the muffler and replace the muffler.

In order to keep the pressure piston in a non-deflected position, can be provided according to claim 3, that a return spring is provided for adjusting the limit pressure in the housing. Against the spring force of this return spring, the pressure piston is deflected when the limit pressure is exceeded. Thus, this solution variant is extremely simple and inexpensive to manufacture.

However, according to claim 4, the pressure piston can also be held in the housing by static friction, which can be achieved for example by an appropriate choice of the material for the pressure piston. When a certain limit pressure is exceeded, this static friction is now overcome and the pressure piston deflected. This solution variant is extremely simple and inexpensive to produce. In particular, this solution variant can also be embodied as an injection-molded component. This solution variant has the advantage that the pressure piston and thus also the signal pin, remains in its deflected position.

According to claim 5 it can be provided that an electronic monitoring device can be activated by the signal pin, which optionally emits an additional visual or audible warning signal. By this embodiment, an always present for controlling the pneumatic control valve electronic control device is included.

This electronic control device can also be controlled according to claim 6 such that an electronic monitoring device can be activated by the signal pin, by which the control valve is deactivated. This means that when the limit pressure is exceeded, the control valve and thus the pneumatic drive is switched off, so that the operator must inevitably change the muffler. Such a configuration may be necessary in manufacturing processes in which it is absolutely necessary that the pneumatic drive is always to operate at the maximum speed.

Furthermore, it can be provided according to claim 7, that the pressure sensor is an electronic pressure sensor which activates a signal device for emitting a warning signal and / or for switching off the pneumatic drive when the limit pressure is exceeded. As a result of this embodiment, the limit pressure can be set precisely, in particular by electronic means, for example via a corresponding display and a correspondingly provided keyboard, so that the monitoring device, in particular according to the embodiments according to claims 2 and 3, operates fully automatically.

Due to the embodiment according to claim 8, the coupling of the muffler to the control valve is extremely easy to carry out. For this purpose, the body is tubular and can be tightly coupled by means of a threaded connector with the vent port. Further, the pressure sensor with the tubular body or a receiving housing, in which the body is interchangeable inserted be removably connected by a press or threaded connection. This in turn has the advantage that even a defective pressure sensor can be replaced in the simplest way.

In summary, it should therefore be stated that the operating state of the silencer according to the invention can be checked in the simplest manner and this silencer can be exchanged if necessary in the case of an appealing pressure sensor. Thus, the reliability of the pneumatic drive is significantly improved, but in particular an increase in pressure during operation is not necessary because clogging by contamination of the muffler is always recognizable by the operator.

Fig. 1

einen Vertikalschnitt durch ein erstes Ausführungsbeispiel eines erfindungsgemäßen Schalldämpfers mit Drucksensor in seiner Ausgangsstellung;

Fig. 2

den Drucksensor aus Fig. 1 im Vertikalschnitt in seiner ausgelösten Position;

Fig. 3

einen Vertikalschnitt durch ein zweites Ausführungsbeispiel eines erfindungsgemäßen Schalldämpfers mit Drucksensor in seiner Ausgangsstellung;

Fig. 4

den Schalldämpfer aus Fig. 3 im Vertikalschnitt in seiner ausgelösten Stellung;

Fig. 5

eine schematische Prinzipdarstellung eines Pneumatikantriebes mit einem Steuerventil und einem doppelseitig wirkenden Pneumatikzylinder.

Reference to the drawing, the invention is explained in more detail by way of example below. It shows:

Fig. 1

a vertical section through a first embodiment of a muffler according to the invention with pressure sensor in its initial position;

Fig. 2

the pressure sensor of Figure 1 in vertical section in its triggered position.

Fig. 3

a vertical section through a second embodiment of a muffler according to the invention with pressure sensor in its initial position;

Fig. 4

the muffler of Figure 3 in vertical section in its tripped position.

Fig. 5

a schematic diagram of a pneumatic actuator with a control valve and a double-acting pneumatic cylinder.

Fig. 1 shows a silencer 1 according to the invention in vertical section. This silencer has a body 2, which is tubular and consists of a porous, air-permeable material. This body 2 defines a cavity 3 and causes a sound attenuation when venting a pressure line of a pneumatic drive. At the lower end of the tubular body 2 is provided with a, this body 2 occlusive connection element 4, which has a coupling thread 5. By means of this coupling thread 5, the muffler 1 according to the invention, for example, with a vent port of a control valve directly coupled.

The tubular body 2 is closed at its end opposite the connecting element 4 by means of a pressure sensor 6. This pressure sensor 6 has a housing part 7, which in the present embodiment is pressed onto the tubular body 2 via a slight press fit. This interference fit is designed such that the housing part 7 in case of need, for example in case of defect of the pressure sensor 6, from the tubular body 2 is manually removable.

The housing part 7 has a central through-bore 8, in which a signal pin 9 of a pressure piston 10 is inserted axially displaceable. To limit the stroke of this pressure piston 10 and the signal pin 9 in the through hole 8 is in the present embodiment a guide pin 11 is provided, which engages in a guide slot 12 of a guide cylinder 13 of the housing part 7 positively and axially adjustable. The maximum travel of the pressure piston 10 is thus precisely defined over the length of the guide slot 12 in the guide cylinder 13. To hold the pressure piston 10 in its starting position shown in Fig. 1, a return spring 14 is provided whose spring forces are dimensioned such that the pressure piston 10 deflected upon reaching a certain, acting in the cavity 3 limit pressure in the direction of arrow 15 upwards becomes.

Due to the deflection of the pressure piston 10, this reaches into the upwardly deflected end position shown in FIG. In this end position, the signal pin 9 protrudes beyond the outer end face 16 of the housing part 7, so that it is visible from the outside by the operator. Thus, the operator is able to recognize that the tubular body 2 is added by contamination and thus the flow of air is hindered such that in the cavity 3, at least for a short time, the pressure when venting a pressure line of a pneumatic actuator on the limit has risen.

It can be seen that this pressure sensor 6 is extremely simple and has an extremely high reliability. The pressure piston 10 is slightly smaller in its diameter than the inner diameter of the tubular body 2, so that between the pressure piston 10 and the body 2, an annular gap 17 is formed. Thus, the pressure piston 10 with its signal pin 9 is approximately frictionless both in the guide cylinder thirteenth as well as received in the tubular body 2, so that a limit pressure on the spring force of the return spring 14 is relatively precisely adjustable.

FIG. 3 shows a vertical section of a second exemplary embodiment of a muffler 20. In this muffler 20, the sound-damping, porous and air-permeable body 21 is designed as a cylindrical tube and interchangeable inserted into a receiving housing 22. This receiving housing 22 has in its side walls in the axial region of the tubular body 21 a plurality of radial, approximately over the entire length of the body 21 extending openings 23.

Furthermore, the receiving housing 22 is also provided in the region of its lower end with a coupling thread 24, via which the receiving housing 22 with a corresponding vent port of a control valve is tightly coupled. Also, the tubular body 21 includes a cavity 25, which communicates via a corresponding vent hole 26 with the pressure line to be vented of a pneumatic drive.

In the embodiment according to FIG. 3, a pressure sensor 27 is interchangeably screwed into the receiving housing 22 at its end opposite the coupling thread 24 via a threaded connection 28. This pressure sensor 27 has an outer end wall 29, which is provided with a central through-bore 30 into which a signal pin 31 of a pressure piston 32 protrudes suitably. In this embodiment, the housing 33 of the pressure sensor 27 and the pressure piston 32 with be made a signal pin 31 as a plastic injection molded part.

In the embodiment according to FIGS. 3 and 4 it is provided that the pressure piston 32 is held by friction in the housing 33. Now increases with increasing contamination of the tubular body 21 when venting a pressure line of a pneumatic actuator, the pressure in the cavity 25 over a predetermined limit pressure, which is determined by the static friction of the pressure piston 32 in the housing 33, the pressure piston 32 from that shown in Fig. 3 Starting position pressed into the end position shown in Fig. 4. In other words, when a corresponding limit pressure is exceeded in the direction of the arrow 15, the pressure piston 32 is pressed from the initial position shown in FIG. 3 into the end position shown in FIG. 4.

It can be seen that also in this case the signal pin 31 protrudes from the outer end face 34 of the housing 33, so that the exceeding of the limit pressure for the operating personnel is recognizable. In the embodiment according to FIGS. 3 and 4, upon reaching this limit pressure, the body 21 can thus be replaced by a new body 21, so that the muffler 20 in turn receives its optimum permeability.

5 shows a schematic representation of a pneumatic drive 40 which is formed from a double-acting pneumatic cylinder 41 and a control valve 42 controlling this pneumatic cylinder 41. The pneumatic cylinder 41 has, as from the prior art is known, a cylinder tube 43, in which a pressure piston 44 is received axially adjustable. With this pressure piston 44 is a piston rod 45 in communication, via which an actuating movement of the pressure piston 44 is transmitted to the outside. It can be seen that the pressure piston 44 divides the cylinder tube 43 into a first pressure chamber 46 and a second pressure chamber 47.

The first pressure chamber 46 is connected via a first pressure line 48 to a first pressure port 49 of the control valve 42 in connection. The second pressure chamber 47 is in turn connected via a second pressure line 50 with a second pressure port 51 of the control valve 42 in connection.

Furthermore, it can be seen from FIG. 5 that the control valve 42 has a first vent connection 52 and a second vent connection 53. With these venting ports 52 and 53, a respective muffler 1/1 or 1/2 is coupled, wherein the muffler 1/1 and 1/2 are shown in Fig. 5 only schematically. Next, a pressure line 54 is connected to the control valve 42, via which the control valve 42 and the control valve 42 to the pneumatic cylinder 41, the corresponding operating pressure is supplied alternately.

In the first functional position of the control valve 42 shown in FIG. 5, the system pressure supplied via the pressure line 54 is supplied via the control valve 42 via the first pressure connection 49 and the first pressure line 48 to the first pressure chamber 46 of the pneumatic cylinder 41. The second pressure line 50 of the pneumatic cylinder 41 is via the second pressure port 51 via the control valve 42 switched to the second vent port 53.

In this functional position, the pressure chamber 46 is thus subjected to system pressure, so that the pressure piston 44 is displaced in the direction of the arrow 55. At the same time, the operating pressure applied in the second pressure chamber 47 is reduced via the second pressure line 50, the second pressure port 51 and via the control valve 42 to the second venting port 53 via the silencer 1/2.

After the pressure piston 44 of the pneumatic cylinder 41 has moved into its right end position in the direction of the arrow 55, the control valve 42 can now be reversed for the return movement. In this second functional position, the second pressure chamber 47 is acted upon by the second pressure line 50 and the second pressure port 51 with operating pressure. At the same time, the first pressure chamber 46 is connected via the first pressure line 48 and the first pressure port 49 to the first vent port 52, so that the previously applied operating pressure in the first pressure chamber 46 is reduced via the silencer 1/1 at the first vent port 52. Since the switching operations of the control valve 42 are substantially abrupt, there is also a sudden pressure reduction in the respective pressure chamber 46 and 47 when switching the control valve 42. This sudden pressure reduction leads to a certain sound pressure, which by the two silencers 1/1 and 1 / 2 is degraded, so that here on this silencer 1/1 and 1/2 a corresponding sound attenuation is effected.

Instead of the purely mechanical pressure sensors, as shown by way of example in FIGS. 1 to 4, it is also possible to provide electronic pressure sensors which actuate a corresponding control device (not shown in the drawing) in such a way that this control device emits a corresponding audible or visual warning signal or causes. Furthermore, it can also be provided that the entire pneumatic drive 40 is switched off when the adjustable limit pressure is exceeded when the warning signal is present.

It can also be provided that by the signal pins 9 and 31 on the respective pressure sensor 6 and 27 attached microswitch is actuated, by which in turn a corresponding control signal for delivering a warning signal is delivered to an electronic monitoring device, which in turn an acoustic or optical Warning signal and / or a shutdown of the pneumatic actuator 40 causes.

It can be seen that the functioning of the respective muffler 1, 1/1, 1/2 or 20 can be checked in a simple manner by the mufflers according to the invention with their pressure sensors 6 and 27.

Claims (8)

Silencer (1, 20) for damping the exiting at pneumatic control valves (42) of a pneumatic actuator (40) sound pressure, consisting of a housing-like body (2, 21), which with the vent port (52, 53) of the control valve (42) can be coupled wherein the body (2, 21) has a porous, air-permeable base structure and includes a cavity (3, 25),
characterized,
in that the body (2, 21) is provided with a pressure sensor (6, 27) which, given increasing dirtiness of the muffler (1, 20) and the concomitant increase in the back pressure within the cavity (3, 25) at a predeterminable limit pressure Warning signal and / or a shutdown of the pneumatic actuator causes. Silencer according to claim 1, characterized in that the pressure sensor (6, 27) consists of a housing (7, 33) arranged pressure piston (10, 32) which is deflected when the limit pressure is exceeded and,
that the pressure piston (10, 32) with a signal pin (9, 31) is coupled, which in the deflection (arrow 15) of the pressure piston (10, 32) visible from the housing (7, 33) is pressed. Silencer according to claim 2, characterized in that for adjusting the limit pressure in the housing (7), a return spring (14) is provided against the spring force of the pressure piston (10) is deflected when the limit pressure is exceeded. Silencer according to claim 2, characterized in that the pressure piston (32) in the housing (33) is held by friction and that when the limit pressure is exceeded the static friction overcome and the pressure piston (32) deflected (arrow 15). Silencer according to claim 2, 3 or 4, characterized in that by the signal pin (9, 31) an electronic monitoring device can be activated, which optionally emits an additional visual or audible warning signal. Silencer according to claim 2, 3 or 4, characterized in that an electronic monitoring device can be activated by the signal pin (9, 31), by which the control valve (42) is deactivated. Silencer according to claim 1, characterized in that the pressure sensor is an electronic pressure sensor, which when exceeding the Grenzdrukkes a signaling device for emitting a warning signal and / or activated for switching off the pneumatic drive. Silencer according to one of claims 1 to 7, characterized in that the body (2, 21) is tubular and by means of a threaded connector (4, 5, 24) with the vent port (52, 53) is tightly coupled and,
in that the pressure sensor (6, 27) is detachably connected to the tubular body (2) or a receiving housing (22) into which the body (21) is replaceably inserted by means of a press or threaded connection (28).

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