US3468261A - Pump - Google Patents

Description

Sept. 23, 1969 H. snmenan PUMP Filed Jan. 23. 1967 FIG.I

'nwsu'ron v n. scmusaag Wold/# ATTORNEY United States Patent O,"

3,468,261 PUMP Heinz Schmierer, Maichingen, Wurttemberg, Germany, assignor to Altec Gesellschaft fur Allgemeine Landtechnik m.b.H., Hailfingen, Wurttemberg, Germany Filed Jan. 23, 1967, Ser. No. 611,119 Int. Cl. F04]! 43/02; F01b 19/00 US. Cl. 103150 9 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The present invention relates to a pump. More specifically, the invention relates to a diaphragm pump.

It is known to construct diaphragm pumps with a cylinder which defines a chamber. The chamber has an end portion and is being bounded by an internal surface. A flexible diaphragm extends across such end portion and is secured to the cylinder and the piston is reciprocably received in the chamber and has an external peripheral surface and end portion which is adjacent to and fixed with the diaphragm. Since the diaphragm is constantly flexed during each working and rest stroke of the piston, it is under particular stress at those areas of the diaphragm which are secured to the cylinder. The diaphragm which consists of an elastomeric material, usually a rubber-like substance, makes it necessary in determining the operating parameters of diaphragm-type pumps to so construct the pump that the distance traversed by the piston during the working and rest strokes thereof can only be relatively small. This, in turn, means that the fluid displacing capacity of such pumps per stroke is very small as compared to pumps of other types. In order to reduce to some extent at least the stresses which act upon the diaphragm at the areas at which the same is secured to the cylinder, it is known to round the internal surfaces of the cylinder end portion or of the piston end portion so that the respective rounded surface defines with the adjacent surface of the other end portion an annular space adjacent to the diaphragm. This space is either completely or partially filled with a usually liquid lubricant and during the operating stroke of the piston the diaphragm is partly elastically displaced into this annular space, thereby displacing the lubricant therefrom. This results in a loss of the volumetric capacity of the pump and this decrease in the capacity becomes larger, the greater the rounding of the surfaces leading to formation of the annular space is selected.

Summary of the invention The present invention overcomes the above-discussed disadvantages of the prior art.

More specifically, the present invention provides a pump which significantly increases the volumetric capacity despite the limited stress-resistance of the diaphragm.

In accordance with one feature of my invention I provide a pump, which includes a cylinder defining a chamice her having an end portion and beingbounded by an internal surface. A flexible diaphragm is provided and extends across the end portion of the chamber, and this diaphragm is secured to the cylinder. A piston is reciprocably accommodated in the chamber and is provided with an external peripheral surface and with an end portion adjacent to and fixed with the diaphragm. At least one of the aforementioned end portions defines with the adjacent surface of the other end portion an annular space which is located adjacent to the diaphragm. Finally, my novel pump also includes an annular insert of elastically yieldable material which is received in the aforementioned annular space.

In accordance with the invention, this annular insert may be of circular or non-circular cross-section, with a triangular cross section being preferred since this configuration is particularly adapted for filling the annular space. Although various different elastic materials are suitable for the annular insert, cross-linked polyurethene elastomer has been found to be particularly advantageous.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Brief description of the drawing FIG. 1 is a partial section through a diaphragm-type pump in accordance with the present invention;

FIG. 2 is a fragmentary section, shown in an enlarged view, illustrating the pump of FIG. 1 during the suction stroke of the piston; and

FIG. 3 is a view substantially similar to FIG. 2, but illustrating the pump of FIG. 1 during the pressure-stroke of the piston.

Description of the preferred embodiments Discussing now the drawing in detail, and firstly FIG. 1 thereof, it will be seen that there is shown a diaphragmtype pump which comprises a cylinder 1 in which there is received a piston 2 for reciprocable movement therein. The piston 2 can be given reciprocatory movement in various ways, for instance via a piston rod 11, and a crank or similar member 12 connected with the piston rod. This is shown in FIG. 1 but only by way of example since it is not essential for the invention. The drive arrangement for the piston is provided in a drive housing 10 which communicates with the chamber defined by cylinder 1.

A cover or lid 4 is rigidly connected with the end portion of the cylinder 1 and this cover defines a chamber 5 and carries an inlet valve 7 and an outlet valve 6. Arranged between the chamber 5 defined within the cover 4 and the chamber which is defined in the cylinder 1, is a diaphragm 3 consisting of elastically yieldable material. Thus, the fluid which is pumped by the pump shown in FIG. 1 and which passes through the chamber 5 in the cover 4 cannot come in contact with the piston 2 or enter into the working chamber defined in cylinder 1 and in which the piston 2 reciprocates.

The end portions of the cover 4 as well as of the cylinder 1 are rounded, that is the respective inner circumferential surfaces of the peripheral walls of cover 4 and of cylinder 1 diverge radially outwardly. Similar rounding will be seen to be provided at the end portion of the piston 2 and the rounding of the end portion of the piston, together with the rounding of the internal surface of the peripheral wall of cylinder 1 and the end portion of the latter results in the provision of a hollow annular space 9. In accordance with the invention, an annular element 8 is disposed in this hollow annular space 9, and completely or at least partially fills the cross-section of the same. This element 8 consists, as pointed out earlier in this specification of a suitable elastomeric material, for intsance of a cross-linked polyurethene elastomer.

FIG. 2 shows that the cross-section of the annular memher 8 may be circular, whereas FIG. 3 shows that the cross-section may be triangular. Of course, neither of these cross-sectional configurations is exclusive of other possibilities, but circular or triangular cross section is preferred.

It is evident from FIGS. 2 and 3 that the accommodation of the annular member, which in FIG. 2 is indicated with reference numeral 8, and in FIG. 3 with reference numeral 8', prevents deflection of the diaphragm 3, into the annular space 9, during the working as well as during the return stroke, thus eliminating excessive stress on such portions of the diaphragm as are normally deflected precisely into this space. Evidently, the provision of this arrangement not only significantly increases the life of the diaphragm over similar constructions known from the prior art but also makes it possible to raise the volumetric capacity of a pump so constructed, thus representing a significant advance in the state of the art. As is evident from all of the figures, the diaphragm 3 is secured by being clamped between the juxtaposed end faces of the cylinder 1 and the cover 4 and can be secured to the piston 2 by means of a screw or bolt 13 and a suitable washer 14, if this is desired. The provision of the inlet valve 7 and the outlet valve 6 has already been mentioned, and it will be specifically seen rom FIG. 1 of the drawing, that a seat 16 and an abutment 16' are provided for the inlet valve 7 on the cover 4, whereas a similar seat and abutment 15' are provided for the outlet valve 6, also on the cover i 4. This is shown for the sake of completeness only and does not constitute a part of the invention which latter is concerned only with the provision of the particular elastomeric annular member 8, 8 in the particular manner described herein.

It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of arrangements, difiering from the types described above.

While the invention has been illustrated and described as embodied in a diaphragm pump, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. A pump, including a cylinder defining an elongated chamber having an end portion and being bounded by an internal surface having a predetermined diameter and flaring continuously outwardly at said end portion of said chamber; a flexible diaphragm extending across said end portion and being secured to said cylinder; a piston reciprocably received in said chamber and having a diameter substantially identical to said predetermined diameter, said piston further having an external peripheral surface and an end portion adjacent to said diaphragm, at least said end portion of said chamber defining with the adjacent surface of the end portion of said piston adjacent to said diaphragm an annular space the volume of which changes during movement of said piston; and an annular insert of elastically yieldable material, having a diameter at most slightly ditferent from said predetermined diameter and being in its entirety normally located in said annular space but with freedom of movement in longitudinal direction of said chamber so as to move in such longitudinal direction during and as the result'of changes of the volume of said annular space during movement of said piston.

2. A pump as defined in claim 1, wherein said external surface of said piston tapers continuously inwardly and defines with said internal surface said annular space.

3. A pump as defined in claim 1, wherein said annular insert is of circular cross-section.

4. A pump as defined in claim 1, wherein said annular insert is of other than circular cross-section.

5. A pump as defined in claim 1, wherein said annular insert is of polygonal cross-section.

6. A pump as defined in claim 1, wherein said annular insert is of triangular cross-section.

7. A pump as defined in claim 1, wherein said annular insert is of elastomeric material.

I 8. A pump as defined in claim 1, wherein said annular insert consists at least predominantly of cross-linked polyurethene elastomer.

9. A pump as defined in claim 1, wherein said end portions diverge in mutually opposite radial directions, and wherein said annular space which they define together with said diaphragm and with one another is of substantially triangular cross-sectional outline.

References Cited UNITED STATES PATENTS 1,945,181 1/1934 Carter 103-150 2,913,007 11/1959 Morrison 103-150 X 3,093,086 6/1963 Altoz et al 103-150 1,198,971 9/1916 Taylor 230- 2,782,719 2/ 1957 Geogias 103-150 2,853,015 9/1957 Pleuger 103-150 2,846,139 8/1958 Blount et al 230-170 2,786,423 3/1957 Coffey 103-150 2,869,474 l/ 1959 Pleuger et al 103-150 3,201,136 8/1965 Harrison et al. 260-775 X WILLIAM L. FREEH, Primary Examiner US Cl. X.R.

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