Patent Application
20140119961
The invention concerns a motor-pump assembly, 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 and an electric motor driving the pump, wherein the pump is provided as a double diaphragm pump with two opposing working diaphragms which are each clamped between a pump housing and a working chamber cover and thus delimit a working chamber and which are movable by means of a crank drive having an eccentric and connecting rods, and wherein the connecting rods each have a connecting rod shank and a connecting rod eye of plastic and are mounted movably on the eccentrics by means of roller bearings.
To provide a vacuum for a pneumatic brake booster, the interior of which is divided into at least one vacuum chamber and one working chamber, vacuum pumps are used which draw in residual air from the vacuum chamber and expel it to the atmosphere. Usually the automotive industry uses vane pumps or variable geometry vane pumps here. In principle these have a great deal of friction and must be lubricated to achieve an acceptable service life. Vacuum pumps with vanes driven by the internal combustion engine of the motor vehicle are therefore connected to the oil circuit of the combustion engine. However a significant proportion of the power emitted by the combustion engine must be used to drive such a pump. This also applies even when the vacuum is already fully formed in the chamber to be evacuated. Therefore it is useful to drive the vacuum pump with electrical energy and only switch it on when the absolute pressure in the vacuum chamber rises above a predetermined value.
Furthermore in vehicles with electric or hybrid drives, the vacuum pump (sometimes) cannot be driven by the combustion engine. Therefore in these vehicles, electrically driven vacuum pumps are used.
Equipping such an electrically driven pump with a lubricant circuit or connecting it to such a circuit would entail a disproportionally high expense. Thus for use in motor vehicles with brake systems with electrically driven vacuum pumps, only dry-running vacuum pumps can be used. For this in vane pumps the self-lubricating material graphite is used, from which the vanes can be produced with the necessary precision with high expense. Therefore efforts have been focused on using a diaphragm pump for electrical provision of a brake vacuum.
A generic motor-pump assembly is already known from DE 10 2007 005 223 A1, which is incorporated by reference. The automotive industry imposes very high requirements in relation to the acoustic comfort of motor vehicle components, and requires suppliers to provide robust, durable pumps with very low noise emission. To meet these requirements, in the known motor-pump assembly, the outlet channels are arranged in the working chamber covers and in the pump housing such that air expelled from the working chambers is conducted into an interior of the pump housing surrounding the crank drive. Furthermore an air outlet unit is provided which allows a low-noise expulsion of air from the interior by deflection of the air. The interior, also called the crank chamber, serves as a sound damping chamber since the expelled air is not conducted directly to the atmosphere. By deflecting the air in the air outlet unit, the noise level can be further substantially reduced so that blow-out noise is almost avoided.
Due to the increasing use of vehicles with electric drives, the acoustic requirements for the motor-pump assembly are rising further.
Therefore an aim of the present invention is to provide a motor-pump assembly which takes into account the rising requirements in relation to acoustic comfort.
This is achieved according to an aspect of the invention in that between each connecting rod eye and the roller bearing, a resilient decoupling is provided which damps a transmission to the roller bearing of vibrations in the connecting rod shank which occur on a force direction change on the rotation of the crank drive. Using the resilient decoupling according to the invention therefore the noise which occurs in the roller bearing by a force direction change on the rotation of the crank drive—in particular by overcoming the bearing play—and which is transmitted to an eccentric via the roller bearing can be minimized or eliminated.
An advantageous embodiment of the invention provides that for resilient decoupling, the roller bearing is provided resiliently embedded in the connecting rod eye. Thus the vibrations occurring on the rotation of the crank drive are only transmitted damped to the roller bearing.
Preferably the resilient decoupling can be provided as an elastomer layer between the connecting rod eye and an outer ring of the roller bearing. The seating of the roller bearing in the connecting rod eye can in this way be achieved with no further components. Furthermore as a result a low bearing play can be provided in the roller bearing.
According to an advantageous embodiment of the invention the roller bearing can easily be integrated in the connecting rod eye in that the elastomer layer is created by injection molding around the roller bearing placed in the connecting rod eye.
A further advantageous alternative embodiment of the invention provides that to receive the roller bearing, a connecting rod ring is provided which is resiliently embedded in the connecting rod eye. Thus the connecting rod ring which is preferably made of metal can form the press joint to the roller bearing, and the bearing can be fixed as previously by pressing into the connecting rod. Thus this production step can also be carried out in existing assembly lines without modification.
In a simple manner the connecting rod ring is provided preferably fixed by injection molding with the elastomer layer.
According to an advantageous embodiment of the invention, a lock can be provided between the connecting rod ring and connecting rod eye, whereby the fixing of the bearing can be ensured.
According to an advantageous embodiment, a simple lock is achieved if a mechanical lock is provided between the connecting rod ring and connecting rod eye. This is preferably provided as a bayonet lock.
A further advantageous embodiment of the invention provides that a resilient lock is provided between the connecting rod ring and connecting rod eye.
The resilient lock is preferably formed by undercuts in the connecting rod ring into which the elastomer layer can flow for locking.
A further improvement of the locking can be achieved according to a preferred embodiment in that on an inside of the connecting rod eye, protrusions are provided which are surrounded by the elastomer layer for locking.
The invention is best understood from the following detailed description when read in connection with the accompanying drawing. Included in the drawings are the following figures:
The pump 2 is provided as a double diaphragm pump with two opposing working diaphragms 4 which are each clamped between the pump housing 5 and a working chamber cover 6 and thus delimit a working chamber 7. The working diaphragms 4 are movable in opposition to each other by means of a crank drive 8, which for each working diaphragm 4 has an eccentric 9 and a connecting rod 10. The working chamber cover 6 has an upper cover 11 and a lower cover 12 which are welded, riveted or screwed together in an air-tight manner.
Inlet and outlet valves (not shown) are provided in the working chamber covers 6. The air expelled from the outlet valve is conducted via an outlet channel in the working chamber cover 6 to an outlet channel in the pump housing 5 which are connected air-tightly by means of a sealing element. The two outlet channels in the pump housing 5 open into an inner chamber 22 of the pump housing 5, the so-called crank chamber, which surrounds the crank drive 8. An air outlet unit 13 provided in or on the pump housing 5 allows a low-noise blow-out of air from the inner chamber 22 so that the inner chamber 22, which is also called the crank chamber, serves as a sound-damping chamber. The air outlet unit 13 comprises a non-return valve 20 having a one-piece or multipiece valve body 18 which prevents a back flow of air already expelled and the penetration of liquid or gaseous substances into the crank chamber 22.
In addition the air-borne noise on expulsion of the air from the inner chamber 22 is reduced in that the air outlet unit 13 has a filter element 17 arranged in a filter housing 14, through which the air escapes to the atmosphere. Furthermore the air outlet unit 13 comprises an air outlet cover 15, an air outlet closing cap 16 and a valve body 18, and is provided as a pre-mountable assembly. The air outlet cover 15, the air outlet closing cap 16 and the filter housing 14 are each attached with screw elements 19, 21. As is evident, the filter housing 14 is riveted to the air outlet cover 15. To deaden the sound, further means can be provided which are advantageously integrated in the air outlet unit assembly 13. For this the air outlet unit 13 can have an intermediate floor by means of which the air is deflected repeatedly as it flows through the air outlet unit 13. Furthermore several filter elements can be provided in the air outlet unit 13.
When the air pressure in the interior 22 of the pump 2 is greater than the atmospheric pressure surrounding the pump 2, the non-return valve 20 opens in that the valve body 18 lifts at least partly from the continuous bores 23 in the filter housing 14 and the air can escape from the pump housing 5 to the atmosphere through openings (not shown) in the air outlet closing cap 16 and through the filter element 17.
Furthermore on the pump housing 5 is provided a connection not shown via which for example a connected brake booster is evacuated.
It is further evident from
The working diaphragm 4 separates the working chamber 7 from the crank chamber 22 and is firmly connected with a tappet 28, wherein the preferably non-deformable tappet 28 is injection molded with the resiliently deformable material of the diaphragm 4. Thus in the vicinity of the tappet 28, a portion 29 which is difficult to deform is produced in the center of the working diaphragm 4 and transforms towards the outside into an easily deformable portion 30, which in turn transforms towards the outside into a diaphragm bead 31 which is connected firmly and air-tightly with the pump housing 5. The tappet 28 can either be injection-molded with the material of the connecting rod 10, firmly connected with the connecting rod 10 by means of a weld or threaded connection, or provided integrally with the connecting rod 10. The connecting rods 10 are mounted movably on the eccentrics 9 by means of roller bearings 32 in the form of ball bearings.
The embodiment examples described below of a motor-pump assembly according to the invention differ from the known motor-pump assembly 1 described in
The same components carry the same reference numerals.
Due to the increased use of vehicles with electric drives, the acoustic requirements imposed on the motor-pump assembly 1 are rising, so that the object to be achieved is to meet the growing requirements for acoustic comfort.
A force direction change in a connecting rod shank 37 of the connecting rod 10 occurs twice on every rotation of the crank drive 8. Due to the bearing play in the roller bearing 32 in the form of a ball bearing, an outer ring 35 of the roller bearing 32—which in known assemblies is press-fitted with a connecting rod eye 33 of the connecting rod 10—impacts with high dynamic on the roller body 36 and a rotating inner ring 34, wherein the excitations occurring are transmitted to the eccentric 9.
Therefore in all four embodiment examples described according to
For this the embodiments provide that for resilient decoupling, the roller bearing 32 is resiliently embedded in the connecting rod eye 33, 33′, 33″ so that the vibrations occurring on rotation of the crank drive 8 are not transmitted or only transmitted damped to the roller bearing 32.
The roller bearing 32 is easily fixed in the connecting rod eye 33 by injection molding with the elastomer layer 38 around the roller bearing 32 placed in the connecting rod eye 33.
A second alternative embodiment is shown in
This alternative embodiment, in contrast to the first embodiment example, provides that to receive the roller bearing 32, a connecting rod ring 39 is provided which is resiliently embedded in the connecting rod eye 33. The embedding is easily achieved by injection molding with the elastomer layer 38 around the connecting rod ring 39. Thus the connecting rod ring 39, which is preferably made of metal, provides the press joint to the outer ring 35 of the roller bearing 32 and the bearing can be fixed as previously by pressing into the connecting rod 10, without any modification of existing assembly lines being required. With this embodiment of the bearing fixing it is not necessary to degrease the outer ring 35 before installation or injection molding.
Also the subsequent press fitting prevents any lubricant present in the roller bearing 32 from escaping on embedding of the connecting rod ring 39.
Two further embodiment examples are shown in
As evident from the section through the connecting rod eye 33′ according to
In contrast,
1 Motor-pump assembly
2 Pump
3 Motor
4 Working diaphragm
5 Pump housing
6 Working chamber cover
7 Working chamber
8 Crank drive
9 Eccentric
10 Connecting rod
11 Upper cover
12 Lower cover
13 Air outlet unit
14 Filter housing
15 Air outlet cover
16 Air outlet closing cap
17 Filter element
18 Valve body
19 Screw element
20 Non-return valve
21 Screw element
22 Interior
23 Continuous bore
24 Motor shaft
25 Bearing
26 Motor housing
27 Eccentric shaft
28 Tappet
29 Portion
30 Portion
31 Sealing bead
32 Roller bearing
33 Connecting rod eye
34 Inner ring
35 Outer ring
36 Roller body
37 Connecting rod shank
38 Elastomer layer
39 Connecting rod ring
40 Protrusion
41 Undercut
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 062 160.9 | Nov 2010 | DE | national |
This application is the U.S. National Phase Application of PCT/EP2011/062901, filed Jul. 27, 2011, which claims priority to German Patent Application No. 10 2010 062 160.9, filed Nov. 30, 2010, the contents of such applications being incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/062901 | 7/27/2011 | WO | 00 | 1/16/2014 |
