GB2037375A

GB2037375A - Diaphragm Pump

Info

Publication number: GB2037375A
Application number: GB7938407A
Authority: GB
Original assignee: Westfaelische Metall Industrie KG Hueck and Co
Current assignee: Westfaelische Metall Industrie KG Hueck and Co
Priority date: 1978-11-25
Filing date: 1979-11-06
Publication date: 1980-07-09
Also published as: FR2442355A1; SE7908141L; DE2851060A1

Abstract

A diaphragm pump has opposed pump chambers separated by a reciprocatory diaphragm 1 and each chamber has a pressure connection 10, (11) and a vacuum connection (12, 13). The pressure connections (10, 11) are connected together by channels (24, 26) within the pump housing 2 and so also are the vacuum connections. The diaphragm is clamped between supporting plates 4, 5 each having an external contour substantially complementary to that of the chamber wall 2, 3 facing it so that in operation dead space within the chamber is minimised. <IMAGE>

Description

SPECIFICATION Diaphragm Pump The invention relates to a diaphragm pump for generating overpressure and underpressure in gaseous media.

A pneumatic installation for driving diaphragmcontrolled operating elements has become known from DE-OS 22 32 956, with which a pressure generator is used, which generates both overpressure and underpressure and delivers both overpressure and underpressure to the operating elements. The pressure generator is not described in detail. A control device for a double-acting pneumatic or hydraulic servo motor has also become known from DE-OS 21 45 619, which likewise makes use of a pressure generator not described in detail, such as a force pump, with simultaneous generation of overpressure and underpressure.

A double chamber diaphragm pump has also become known wherein a common electrical drive drives two individual diaphragm pumps, one of which generates the overpressure and the other the underpressure. Although the said double chamber diaphragm pump is suitable for the two aforesaid forms of application, it nevertheless exhibits various disadvantages.

According to the present invention, there is provided diaphragm pump for generating overpressure and underpressure in gaseous media, comprising respective pump chambers on opposite sides of and mutually separated by a diaphragm connected to reciprocatory drive means, each said pump chamber having both an overpressure connection and an underpressure connection.

By these means it is possible to use a shorter stroke for a given capacity with an additionally reduced driving speed, which assists quiteness of operation. Because the stroke is utilised in both directions, a very high efficiency for the overpressure and underpressure sides can be achieved. The effective diaphragm diameter can be made comparatively small.

Two embodiments of the invention will be described by way of example with reference to Figs. 1 to 5 of the accompanying drawings, in which: Fig. 1 shows a diaphragm pump according to the invention with its drive in section, Fig. 2 shows the inlet and outlet valves of the pump in Fig. 1, Figs. 3 and 4 are sectional views of the housing parts of another diaphragm pump according to the invention, and Fig. 5 is a view from below of the housing part of Fig. 3.

The diaphragm pump according to Fig. 1 has two pump chambers, which are mutually separated by a common diaphragm 1. The pump comprises two housing parts 2 and 3 which may for example be made of plastics material. They may be joined together e.g. by a snap connection, whilst the diaphragm 1 is gripped by its rim portion between the two housing parts 2 and 3.

Within the housing the diaphragm 1 is clamped between two diaphragm plates 4 and 5 which are connected to a reciprocatory drive.

The drive may consist e.g. of an electric motor 6 which drives a connecting rod 7 through an eccentric. A screw 8 connects the diaphragm plates 4 and 5 to the rod 7. A moulding 9 of a rubbery elastic material, through which the connecting rod passes, is inserted into the wall of the housing part 2. The moulding 9 is constructed at least partially with concertina-like folds and it serves to seal the adjoining pump chamber with respect to the drive and permits the required degree of movement of the connecting rod.

Both the diaphragm plates 4 and 5 and the pump walls of the housing parts 2 and 3 are constructed as spherical sections. By this means a particularly small dead space is obtained in the contraction of the volume of each pump chamber and the efficiency of the pump is increased. The stroke of the drive is determined so that the diaphragm plates 4 and 5 in their respective limit positions do not quite abut against the associated housing walls. During the movement of the connecting rod, the diaphragm plates, which are shaped as spherical sections, are moved not only up and down, but also rollingly so to speak to a small degree on the inner wall of the pump chamber which is likewise constructed concavely as a spherical section. As a result of these measures the diaphragm pump is also extremely quiet in operation.

Overpressure connections 10 and 11 and underpressure connections 12 and 13 of the pump according to Fig. 1 are illustrated in Fig. 2.

Only the actual connections and those parts of the pump chamber walls co-operating with them are shown in section. The remaining parts of the pump are not sectioned. As Fig. 2 clearly shows, the respective connections are constructed as plastics mouldings which are fixed by snap fastening in the housing parts 2 and 3. The connections, each conjointly with a rubbery elastic diaphragm which is inserted and with correspondingly constructed orifices of the chamber wall, constitute in each case a valve which permits the outflow of the pumped medium from the two pump chambers at an overpressure in the case of the connections 10 and 11, and the connection of the underpressure system to the two pump chambers for the purpose of evacuation in the case of the connections 12 and 1 3.

The arrangement and shape of the pump parts shown is able to achieve a high efficiency for the overpressure and underpressure sides. The stroke of the pump is utilised in both directions.

Overpressure and underpressure phases are generated twice per motor revolution. This is roughly comparable in the characteristic curve with full wave rectification in an electrical circuit.

Pneumatically an effect is achieved which lies approximately between a plunger pump in which underpressure and overpressure are generated pulsatorily once per motor revolution, and a uniform delivery pump, e.g. a positive displacement pump or a blower. Due to the high efficiency, the drive power can be relatively low and the effective diaphragm diameter comparatively small.

Another construction of the pump chambers is illustrated in section in Figs. 3 and 4. Fig. 3 shows in section a housing part 21 which constitutes the wall of the pump chamber remote from the drive side, whereas Fig. 4 shows in section a housing part 22 which constitutes the wall of the pump chamber located at the same side as the drive.

Both components can, like the first-described example, be fabricated of plastics material and be fixed together with a snap connection.

Whereas in the pump according to Figs. 1 and 2, the connections 10 and 13 are inserted into the chamber walls from the outside and serve to form the necessary valves, in the pump according to Figs. 3 and 4 mouldings are inserted into the inside of the chamber walls to provide the induction and outlet valves for the underpressure and overpressure sides. The overpressure valve of the housing section 21 opens into a channel 24, whereas the underpressure valve opens into a channel 25. In the same way the overpressure valve of the housing section 22 opens into a channel 26 and the underpressure valve into a channel 27.

During the assembly of the housing sections 21 and 22, the diaphragm is interposed between them to form the two pump chambers of the diaphragm pump and is provided with diaphragm plates and with a drive in the same way as the pump according to Figs. 1 and 2. The rim portion of said diaphragm is made considerably wider than would be necessary for clamping and sealing, because it also serves to seal the positions where the channel 26 and the channel 24 (overpressure) meet together, likewise the channel 25 and the channel 27 (underpressure).

In each of these positions the rim portion of the diaphragm has an aperture which permits the connection between the associated channels and simultaneously ensures the necessary sealing at the connection position with reference to the pump chambers.

A cover part 28 is superposed on the housing part 21 with interposition of a seal 29. It has an overpressure connection 28a and an underpressure connection 28b. Fig. 5 shows the cover in plan.

By the arrangement of the channels 24 to 27, it is ensured that the diaphragm pump, despite its two chambers, has only one overpressure connection and one underpressure connection, and can therefore easily be connected to the required consumption devices, e.g. to a central locking system in a motor vehicle. The cover part 28 may also be replaced e.g. by a control device for such purposes. By virtue of the internal connections according to Figs. 3 and 4, a highly compact and lowloss device is thus provided.

The two pump chambers may also be connected in series instead of in parallel, thereby achieving a higher underpressure and overpressure. In this case also, the advantages of the high efficiency, compact construction and quiet running are obtained. The connection in series may be effected e.g. by a similar connection through channels as in the example of the embodiment in Figs. 3, 4 and 5, or through a valve in the diaphragm with the two diaphragm plates separating the two chambers.

Claims

1. Diaphragm pump for generating overpressure and underpressure in gaseous media, comprising respective pump chambers on opposite sides of and mutually separated by a diaphragm connected to reciprocatory drive means, each said pump chamber having both an overpressure connection and an underpressure connection.

2. Diaphragm pump according to claim 1 wherein said overpressure and underpressure connections of both pump chambers are connected together in a common housing.

3. Diaphragm pump according to claim 2 wherein the housing comprises two housing parts which are attached together and enclose the diaphragm between them, and channels in the housing parts provide communication between the respective overpressure connections and between the respective underpressure connections.

4. Diaphragm pump according to claim 3, wherein the diaphragm is provided with a marginal portion which serves as a seal between the two housing parts.

5. Diaphragm pump according to any one of the preceding claims wherein the diaphragm is held between two diaphragm plates which are connected to the drive means.

6. Diaphragm pump according to claim 5, wherein the diaphragm plates each have a surface facing an end wall of its respective pump chamber, said surface having a substantially complementary configuration to that of the facing pump chamber wall.

7. Diaphragm pump according to claim 6 wherein said surface of the diaphragm plates and said pump chamber walls are formed as substantially spherical sections.

8. Diaphragm pump according to any one of the preceding claims, wherein the drive means comprises a connecting rod that extends through the pump chamber wall with which it is sealed with the aid of a rubbery elastic moulding.

9. Diaphragm pump according to claim 8, wherein the moulding is constructed at least partially with one or more concertina-like corrugations.

10. Diaphragm pump constructed and arranged for use and operation substantially as described herein with reference to the accompanying drawings.