DE102010042553A1 - Pump unit, particularly for supplying pressure to brake actuating device of motor vehicle brake system, has pneumatic brake booster, particularly vacuum brake booster, where pump is driven by drive unit or motor - Google Patents

Abstract

The pump unit (1) has a pneumatic brake booster, particularly a vacuum brake booster, where a pump (2) is driven by a drive unit or motor (3). A working membrane (4) is provided, which acts on an upward stroke direction, where an eccentric cam (17) is driven by the drive unit. The working membrane is firmly connected with a spring retainer (20).

Description

The invention relates to a pump unit, in particular for providing pressure for a brake actuator of a motor vehicle brake system with a pneumatic brake booster, in particular a vacuum brake booster, comprising a pump and a drive driving the pump, wherein the pump is provided as a double diaphragm pump with two opposite working membranes, each with a work space cap limits a work space.

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. In the automotive industry for this purpose usually vane pumps or swing vane pumps are used. These have inherent friction and must be lubricated to achieve an acceptable life. Vacuum pumps with wings driven by the internal combustion engine of the motor vehicle are therefore connected to the oil circuit of the internal combustion engine. Nevertheless, a significant proportion of the output from the engine power must be used to drive such a pump. And this even if the vacuum is already fully formed in the chamber to be evacuated. Therefore, it is useful to operate the vacuum pump with electrical energy and only turn on when the absolute pressure in the vacuum chamber rises above a predetermined value.

Furthermore, in vehicles with electric or hybrid drive, the vacuum pump is not or temporarily not driven by the internal combustion engine. Therefore, electrically powered vacuum pumps are used in these vehicles.

To equip such an electrically driven pump with a lubricant circuit or to connect to such a, would mean a disproportionate effort. Thus come for use in motor vehicles with brake systems with electrically driven vacuum pump only dry-running vacuum pumps in question. In vane pumps, the self-lubricating graphite material is used, from which the wings are manufactured with the required precision at great expense. Therefore, efforts have been made to use a working diaphragm pump for providing electrical brake vacuum.

Such a motor-pump unit is for example from the DE 10 2009 054 499 A1 known and comprises a double diaphragm pump with two opposite working diaphragms, which are each movable by means of an eccentric and connecting rod having crank drive. This known mechanical deflection of the working diaphragm causes the working diaphragm to perform a flexing movement, which stresses the working diaphragm.

There are always efforts to reduce manufacturing costs and assembly costs, and to improve the efficiency of the pump unit. It is therefore an object of the present invention to provide a cost-reduced pump unit with an improved efficiency, which requires a reduced installation costs with a reduced number of components compared to the known, generic unit.

The object is achieved in that the working diaphragms are assigned an acting in the upstroke direction, driven by the drive eccentric and each one provided for working diaphragm return spring element. As a result, the forced coupling of the working diaphragm is canceled on the eccentric, so that the working diaphragm can perform an up and down stroke in the vertical direction relative to the longitudinal axis of the pump. This requires a reduced flexing movement and thus a reduction of the working membrane load. Furthermore, this can increase the efficiency of the pump.

According to an advantageous embodiment of the invention, a first end of the spring element is supported on a spring receptacle and a second end of the spring element on a guide element, wherein the working diaphragm firmly connected to the spring receptacle and guided the spring receptacle in the guide member during the up and down stroke of the working diaphragm is provided, whereby a simple construction of the pump can be achieved.

For simpler design of the pump housing is preferably provided that the working diaphragm is provided clamped between the working space cover and the guide element.

A reduction in the friction between the spring seat and eccentric can be achieved according to an advantageous embodiment by a rolling bearing is provided on the eccentric.

In this case, a needle bearing is preferably provided on the eccentric. This can do that Packaging can be optimized because the space for a needle bearing is particularly low.

A further reduction of the friction can be achieved according to an advantageous development of the invention in that the spring retainer has a sliding element on its end face acted upon by the eccentric.

An advantageous embodiment of the invention provides that the drive of the pump is provided as a motor. The pump unit can thus be positioned as a motor-pump unit relatively independent of other vehicle components.

An alternative advantageous embodiment of the invention provides that the drive of the pump takes place by means of a camshaft. Thus, the camshaft of the vehicle engine can be used as a drive and a separate drive component is eliminated.

A particularly advantageous in relation to the number of components development provides that the eccentric is provided integrally with the camshaft.

Other features, advantages and applications of the invention will become apparent from the following description of exemplary embodiments and with reference to the drawings.

It shows schematically in longitudinal section:

1 a first embodiment of a pump unit according to the invention and

2 A second embodiment of a pump unit according to the invention.

1 shows a first embodiment of a pump unit according to the invention 1 in longitudinal section, 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 can be seen in particular from the sectional view, is as a double diaphragm pump with two opposite working membranes 4 provided, each with a work space cover 6 a workroom 7 limited.

The in 1 shown work space cover 6 has an upper lid 8th and a lower lid 9 on, which are airtight welded together, riveted or screwed. To reduce costs, the upper cover 8th For example, provided plastic and under cover 9 be formed as a stamped part. An equally cost-effective alternative provides that the lower lid 9 made by die-casting aluminum. It is also possible to design the lower lid 9 as a sintered part.

In each of the working space lids 6 is one in the upper lid 8th trained inlet channel 10 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 11 weiterleitet, which may be formed for example as a plate valve with a valve disc made of elastic material.

After flowing through the inlet valve 11 the sucked air passes through one or more working space lid openings 12 in the lower lid 12 in the workroom 7 between working membrane 4 and workspace lid 6 , is compressed there and over further work space lid openings 13 to the exhaust valve 14 out, which may also be formed as a plate valve with a valve disc made of elastomeric material. As can be seen, is an outlet channel 15 between upper lid 8th and lower lid 9 educated.

From the outlet valve 14 The ejected air is via the outlet channel 15 in the workspace lid 6 to an outlet channel, not shown in the pump housing 5 directed. The two outlet channels 15 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 16 of the pump housing 5 ,

One in the pump housing 5 provided, not shown air outlet unit can be a low-noise blowing out of the air from the interior 22 allow, which thus serves as Schalldämpfungsraum.

How out 1 is apparent, are the working membranes 4 an upward-acting, from the engine 3 driven, on a motor shaft 18 arranged eccentric 17 and in each case one provided for working diaphragm return spring element 19 assigned. This is the working membrane 4 and the eccentric 17 decoupled, leaving the working diaphragm 4 in each case one up and down stroke in the vertical direction with respect to a longitudinal axis M of the pump 2 can perform. The consequent reduced Walk movement of the working diaphragm 4 allows a reduction of the working membrane load. Furthermore, this can increase the efficiency of the pump 2 increase.

A first end 21 of the spring element provided as a compression spring 19 , is supported by a spring retainer 20 starting with which the working diaphragm 4 is firmly connected. Next is a second end 22 of the spring element 19 on a guide element 23 off which is the spring retainer 20 during the up and down stroke.

Here is the working membrane 4 between the workspace lid 6 and the guide element 23 clamped, leaving the pump housing 5 can be made simpler.

By the rotation of the eccentric 17 become the opposite working membrane 4 or the associated with this spring recordings 20 alternately in the upstroke direction, ie in the direction of the working space cover 6 pushed. For this there is a front page 24 on the eccentric 17 at. To the resulting friction between spring recording 20 and eccentric 17 to reduce is on the eccentric 17 a rolling bearing 25 intended. Used as a rolling bearing 25 a needle bearing provided, the packaging of the pump unit 1 be optimized because the space for a needle roller bearing is particularly low.

A further reduction of friction is achieved by the spring retainer 20 at its end acted upon by the eccentric 24 a sliding element 26 having.

2 shows a second embodiment of a pump unit according to the invention 1 , This differs only in the design of the pump drive, so that the same components are provided with the same reference numerals and is omitted a repeated description.

As 2 it can be seen which the pump unit 1 of the second embodiment in longitudinal section, the drive of the pump takes place 2 by means of a camshaft 26 passing through a sealing element 27 sealed in the pump housing 5 protrudes. For example, if the existing camshaft of the vehicle engine is used, so a separate drive component can be omitted. The pump unit 1 can then be flanged directly to the vehicle engine.

To further reduce the component eccentric 17 also in one piece with the camshaft 26 be provided.

LIST OF REFERENCE NUMBERS

1

Motor-pump unit

2

pump

3

engine

4

working diaphragm

5

pump housing

6

Working chamber cover

7

working space

8th

top cover

9

under cover

10

inlet channel

11

intake valve

12

Working chamber cover opening

13

Working chamber cover opening

14

outlet valve

15

exhaust port

16

inner space

17

eccentric

18

motor shaft

19

spring element

20

spring mount

21

The End

22

The End

23

guide element

24

front

25

roller bearing

26

Slide

27

camshaft

28

sealing element

M

longitudinal axis

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 [0005]

Claims (9)

Pump unit ( 1 ), in particular for providing pressure for a brake actuation device of a motor vehicle brake system with a pneumatic brake booster, in particular a vacuum brake booster, comprising a pump ( 2 ) and one the pump ( 2 ) driving drive ( 3 ; 27 ), whereby the pump ( 2 ) as a double membrane pump with two opposing working membranes ( 4 ) is provided, each with a working space cover ( 6 ) a work space ( 7 ), characterized in that the working membranes ( 4 ) acting in the upstroke direction of the drive ( 3 ; 27 ) driven eccentric ( 17 ) and in each case one provided for working diaphragm return spring element ( 19 ) assigned. Pump unit ( 1 ) according to claim 1, characterized in that a first end ( 21 ) of the spring element ( 19 ) on a spring receiver ( 20 ) and a second end ( 22 ) of the spring element ( 19 ) on a guide element ( 23 ), whereby the working membrane ( 4 ) with the spring receiver ( 20 ) and the spring retainer ( 20 ) in the guide element ( 23 ) during the up and down stroke of the working membrane ( 4 ) is provided guided. Pump unit ( 1 ) according to claim 2, characterized in that the working membrane ( 4 ) between the working space lid ( 6 ) and the guide element ( 23 ) is provided clamped. Pump unit ( 1 ) according to one of claims 1 to 3, characterized in that on the eccentric ( 17 ) a rolling bearing ( 25 ) is provided. Pump unit ( 1 ) according to claim 4, characterized in that on the eccentric ( 17 ) A needle bearing is provided. Pump unit ( 1 ) according to one of claims 1 to 5, characterized in that the spring receptacle ( 20 ) at its from the eccentric ( 17 ) acted upon front side ( 24 ) a sliding element ( 25 ) having. Pump unit ( 1 ) according to one of the preceding claims, characterized in that the drive of the pump ( 2 ) as an engine ( 3 ) is provided. Pump unit ( 1 ) according to one of the preceding claims 1 to 6, characterized in that the drive of the pump ( 2 ) by means of a camshaft ( 27 ) he follows. Pump unit ( 1 ) according to claim 8, characterized in that the eccentric ( 17 ) in one piece with the camshaft ( 27 ) is provided.

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