DE102010042552A1 - Method for coating membrane of diaphragm pump for electrical propelled vacuum pump of motor car, has intake channel and exhaust passage assigned to workspace, and membrane whose coating is carried out into workspace via sliding mediums - Google Patents

Abstract

The method involves providing negative pressure for a brake actuating device of a motor vehicle brake system with a pneumatic brake booster. A membrane (4) is clamped between a pump housing (5) and a working chamber cover (6) in order to limit a work space. An intake channel with an inlet valve and an exhaust passage with an exhaust valve are assigned to the workspace. A coating of the membrane is carried out into the workspace via aspirating sliding medium i.e. sliding graphite, by the intake channel. An independent claim is also included for a diaphragm pump comprising a membrane for a motor pump unit.

Description

The invention relates to a method for coating a membrane of a diaphragm pump for a motor-pump unit, which is provided in particular for providing negative pressure for a brake actuator of a motor vehicle brake system with a pneumatic brake booster, wherein the membrane is clamped between a pump housing and a working space cover and thereby a working space limited, wherein the working space is associated with an inlet channel with inlet valve and an outlet channel with outlet valve.

To provide vacuum for a pneumatic brake booster, the interior of which is subdivided into at least one vacuum chamber and a working chamber, vacuum pumps are used which suck in residual air from the vacuum chamber and eject it into the atmosphere. Since in vehicles with electric or hybrid drive, the vacuum pump can not or temporarily can not be driven by the internal combustion engine, electrically powered vacuum pumps in the form of a motor-pump unit are used in these vehicles.

Since high demands are placed on a motor-pump unit for a motor vehicle with regard to manufacturing costs, weight and noise emission, motor-driven pump unit with a diaphragm pump is frequently used.

Such a motor-pump unit is for example from the DE 10 2009 054 499 A1 known and includes a double diaphragm pump with two opposite membranes, which are each movable by means of an eccentric and connecting rod crank drive. The membrane separates the working space from the crank space and is fixedly connected to a plunger, so that in the vicinity of the plunger, a heavily deformable portion in the center of the membrane is formed, which merges outwardly into an easily deformable portion of the membrane. This in turn goes out into a membrane bead, which is firmly and airtight connected to the pump housing. The membrane and in particular its easily deformable portion are subjected to high stress by the lifting movement of the ram moved by the crank drive. To protect against wear, the membrane is greased before assembly. However, this greasing is time-consuming, only partially automatable and poorly reproducible.

It is therefore an object of the present invention to provide a method for coating the membrane, with which the membrane can be reliably protected against wear and which can be carried out fully automatically.

To solve this problem, a method is proposed, the peculiarity is that the coating of the membrane is carried out by sucking a sliding medium through the inlet channel into the working space. The sliding medium is entrained by the air flow during the suction process and distributes itself evenly on the membrane. The coating of the membrane can thus take place after assembly of the motor-pump unit and a complex, partial manual lubrication is avoided.

Preferably, the suction of the sliding medium is performed simultaneously with a functional test of the motor-pump unit, so that no additional step is required for the coating.

The process can be further optimized by the coating is integrated according to an advantageous embodiment of the method according to the invention in a manufacturing process of the motor-pump unit.

Preferably, the sliding medium is filled by means of a metering unit fully automatically into the inlet channel of the diaphragm pump. This ensures the reproducibility of the coating.

According to advantageous embodiments, graphite or talcum is used as the sliding medium.

Other features, advantages and applications of the method according to the invention will become apparent from the following description of an embodiment and with reference to the drawings.

It shows:

1 a known motor-pump unit in a spatial representation;

2 the engine-pump unit according to 1 in longitudinal section through a first plane;

3 the work space cover according to 1 in longitudinal section through a second plane;

4 a schematic representation of a circuit arrangement for a method according to the invention;

5 a time-pressure diagram of a motor-pump unit and

6 a time-temperature diagram of a motor-pump unit.

The 1 to 3 is a well-known engine pump unit 1 can be found in which a method according to the invention can be applied. However, the application of the method is not on the known motor-pump unit 1 limited, but it can in principle be used in all diaphragm pumps.

1 shows the motor pump unit 1 in an exploded view, which is a pump 2 with a pump housing 5 and one the pump 2 driving electric motor 3 includes, wherein the engine 3 for example, can be designed as a DC motor.

The pump 2 , as in particular from the sectional view according to 2 is apparent as a double diaphragm pump with two opposing membranes 4 provided, which in each case between the pump housing 5 and a work space cover 6 is clamped and thereby a working space 7 limited. The membrane 4 are by means of a crank drive 8th movable in opposite directions, which ever membrane 4 an eccentric 9 and a connecting rod 10 includes.

The in 3 in section shown work space cover 6 has an upper lid 11 and a lower lid 12 on, which are airtight welded together, riveted or screwed. In each of the working space lids 6 is one in the upper lid 11 trained inlet channel 13 provided with channels in the pump housing 5 is connected airtight by means of a sealing element and the sucked air to an inlet valve 14 forwards. The inlet valve 14 is as a plate valve with a valve disc 15 made of elastic material.

After flowing through the inlet valve 14 the sucked air passes through working space lid openings 17 in the lower lid 12 in the workroom 7 between membrane 4 and workspace lid 6 , is compressed there and over further work space lid openings 18 to the exhaust valve 19 guided, which also as a plate valve with a valve disc 20 is formed of elastomeric material. As can be seen, is an outlet channel 21 between upper lid 11 and lower lid 12 educated.

From the outlet valve 19 The ejected air is via the outlet channel 21 in the workspace lid 6 to an outlet channel, not shown in the pump housing 5 directed. The outlet channels 21 in the work space lids 6 and in the pump housing 5 are connected airtight by means of a sealing element. The two outlet channels in the pump housing 5 lead into an interior 22 of the pump housing 5 , the so-called crank space, which the crank drive 8th surrounds.

One in the pump housing 5 provided, only schematically illustrated air outlet unit 23 allows a low-noise blowing out of the air from the interior 22 , The interior 22 serves as a soundproofing room.

A holding element 16 in the area of the inlet valve 14 holds the valve disc 15 on the upper lid 11 and at the same time ensures a reduction of the workspace dead space. This can increase the vacuum.

The pump housing 5 is made of plastic, whereby a cost-effective production is made possible. Like that 1 and 2 can be taken is between the engine 3 and the pump housing 5 a in 8th illustrated engine plate 24 arranged, which on a motor flange side 25 of the pump housing 5 is attached and from the engine 3 emits emitted EMC radiation.

The fastening of the engine 3 and the engine plate 24 on the pump housing 5 done by means of screw elements 26 , which directly into the pump housing 5 be screwed.

Further is 2 to see that a motor shaft 27 simultaneously serves as an eccentric shaft in this embodiment, which the crank drive 8th with the eccentrics 9 and the connecting rods 10 wearing.

However, it is also possible a separate version of motor shaft and eccentric shaft.

The above-mentioned air outlet unit 23 is for installation in a breakthrough 28 one to the engine 3 opposite wall 29 of the pump housing 5 intended. It fulfills the breakthrough 28 before installing the air outlet unit 23 the function of a mounting window giving access to the interior 22 of the pump housing 5 allowed.

Furthermore, it is off 1 to see that the inlet channels 13 over in the pump housing 5 extending channels are connected and in a common connection 30 open, which is connected via a vacuum hose, not shown, with a vacuum chamber of the brake booster, not shown.

2 can also be seen that for vibration optimization at the eccentrics 9 each one-piece a balance weight 31 is formed, wherein the eccentric 9 for example, as sintered components are made. This embodiment of the eccentric 9 conditioned on the one hand a cost-effective production and a simplified assembly, since the assembly of balancing weights 72 at the eccentrics 9 can be omitted by screwing, welding, etc., and on the other a further component reduction.

The membrane 4 separates each workroom 7 from the crank room 22 and is stuck with a pestle 32 is connected so that in the environment of the plunger 32 a hard deformable section 33 in the center of the membrane 4 arises, which outwardly into an easily deformable section 34 the membrane passes. This in turn goes outward into a Membranwulst 35 over, with the pump housing 5 firmly and airtight is connected. The membrane 4 and in particular its easily deformable section 34 be by the lifting movement of the crank drive 8th moving pestle 32 heavily used. To protect against wear, the membrane must 4 be coated with a lubricant.

In order to offer a method for coating the membrane, with which the membrane can be reliably protected against wear and which can be carried out fully automatically, the method according to the invention provides that the coating of the membrane 4 by sucking in a sliding medium via the inlet channels 13 in the workrooms 7 he follows.

The lubricating medium, such as graphite or talcum, is entrained in the intake by the air flow and distributed evenly in the workrooms 7 and therefore also on the membranes 4 , Coating the membrane 4 can thus after installation of the motor-pump unit 1 done and a costly, partially manual lubrication is avoided.

4 shows a schematically illustrated circuit arrangement. As can be seen, the suction of the sliding medium is simultaneously with a functional test of the motor-pump unit 1 carried out so that no additional step is required for the coating. For the functional test is a test volume 36 from for example 51 available, which to the connection 30 is connected. During the functional test, sensors are used 37 . 38 characteristic values such as pressure, current, time, voltage etc. measured, which are an evaluation device 39 are supplied, are generated by means of the characteristic characteristics m. As an example of a characteristic characteristic, a time-pressure diagram and a time-current diagram are mentioned, which the 5 and 6 can be seen.

Further process optimization is achieved by the functional test and the simultaneous coating process in a manufacturing process of the motor-pump unit 1 is integrated.

To ensure the reproducibility of the coating, the sliding medium by means of an in 4 shown dosing unit 40 fully automatic in the inlet channel 13 the diaphragm pump 2 filled.

As a sliding medium, as already mentioned above, for example, talc or graphite used. In the context of the invention, however, other lubricants can be used, which are suitable for distribution by means of the air flow.

LIST OF REFERENCE NUMBERS

1

Motor-pump unit

2

pump

3

engine

4

membrane

5

pump housing

6

Working chamber cover

7

working space

8th

crank drive

9

eccentric

10

connecting rod

11

top cover

12

under cover

13

inlet channel

14

intake valve

15

valve discs

16

retaining element

17

Working chamber cover opening

18

Working chamber cover opening

19

outlet valve

20

valve disc

21

exhaust port

22

inner space

23

air outlet

24

motor sheet

25

Motorflanschseite

26

screw

27

motor shaft

28

breakthrough

29

wall

30

connection

31

balance weight

32

tappet

33

section

34

section

35

diaphragm bead

36

Test volume

37

sensor

38

sensor

39

evaluation

40

dosing

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009054499 A1 [0004]

Claims (7)

Process for coating a membrane ( 4 ) a diaphragm pump ( 2 ) for a motor-pump unit ( 1 ), which is provided in particular for the provision of negative pressure for a brake actuation device of a motor vehicle brake system with a pneumatic brake booster, wherein the membrane ( 4 ) between a pump housing ( 5 ) and a work space lid ( 6 ) and thereby a work space ( 7 ), whereby the working space ( 7 ) an inlet channel ( 13 ) with inlet valve ( 14 ) and an outlet channel ( 21 ) with exhaust valve ( 19 ), characterized in that the coating of the membrane ( 4 ) by sucking in a sliding medium via the inlet channel ( 13 ) in the working space ( 7 ) he follows. A method according to claim 1, characterized in that the suction of the sliding medium simultaneously with a functional test of the motor-pump unit ( 1 ) is carried out. A method according to claim 2, characterized in that the coating in a manufacturing process of the motor-pump unit ( 1 ) is integrated. Method according to one of claims 1 to 3, characterized in that the sliding medium by means of a metering unit ( 49 ) fully automatically into the inlet channel ( 13 ) of the membrane pump ( 2 ) is filled. Method according to one of claims 1 to 4, characterized in that is used as a sliding medium graphite. Method according to one of claims 1 to 4, characterized in that talcum is used as sliding medium. Diaphragm pump ( 2 ) with at least one membrane ( 4 ), in particular for a motor-pump unit ( 1 ), which is provided for the provision of negative pressure for a brake actuation device of a motor vehicle brake system with a pneumatic brake booster, wherein the membrane ( 4 ) between a pump housing ( 5 ) and a work space lid ( 6 ) and thereby a work space ( 7 ), whereby the working space ( 7 ) an inlet channel ( 13 ) with inlet valve ( 14 ) and an outlet channel ( 21 ) with exhaust valve ( 19 ), characterized in that the coating of the membrane ( 4 ) by a coating process according to any one of claims 1 to 6 takes place.

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