The present invention relates to a multi-piston pump as generically defined by the preamble to claim 1.
One such multi-piston pump is known for instance from German Patent Disclosure DE 101 53 834 A1. Such multi-piston pumps are used in motor vehicles, for instance, for building up the pressure in brake systems. The known multi-piston pump has two eccentrics, which are located in series and each drive three piston pumps. The piston pumps are disposed in two parallel planes at the level of the eccentrics. The piston pumps, each associated with an eccentric, are disposed at different angles to one another around the eccentric. To avoid pressure pulsations, two piston pumps of the first eccentric are connected to a piston pump of the second eccentric, and two piston pumps of the second eccentric are connected to a piston pump of the first eccentric. The eccentrics are disposed rotated by an angle of approximately 150° to one another. However, it has been proved in this respect that on the one hand the production effort and expense for such a multi-piston pump are quite high, since many low- and high-pressure lines have to be accommodated in the same housing. Moreover, the disposition of the piston pumps leads to non-uniform mechanical forces on a bearing of the motor and of the eccentric shaft. Moreover, the solution to this problem as proposed in this reference has the disadvantage that the hydraulic lengths of the bores of the first and second brake circuit differ, so that there are different pressure buildup times in the multi-piston pump.
The multi-piston pump according to the invention having the characteristics of claim 1 has the advantage over the prior art that it assures a uniform revolving load on a driveshaft and on the bearing that supports the driveshaft. As a result, noise can also be reduced, and in particular, pulsation-free pumping can be achieved. The multi-piston pump of the invention can furthermore be produced more simply and less expensively. This is attained according to the invention by providing that each piston pump of a first pump unit is disposed parallel to a piston pump of a second pump unit. It is thus assured that the piston pumps of the first and second pump units are disposed in the same way. This avoids the problem in which a different disposition of the piston pumps causes non-uniform mechanical forces to be exerted on the driveshaft and the bearings. The parallel disposition of the piston pumps of the first and second pump units furthermore makes for a reduced number of directions from which manufacture and assembly have to be done. In addition, the parallel disposition can also assure that line lengths of the lines from and to the first pump unit and of the lines from and to the second pump unit can be made equal. This has the major advantage that because of this, equal response times of different brake circuits that are supplied by the first and second pump units, respectively, can be achieved. Hence the brake circuits can be connected directly to a high-pressure switching valve in each brake circuit, without detours.
The dependent claims recite further advantageous features of the embodiment according to the invention.
Preferably, the first and second pump units include three piston pumps each. The piston pumps are preferably each disposed at an angle of 120° on the first and second eccentrics.
A further advantage is that the two brake circuits can now be embodied hydraulically symmetrically as well, which further facilitates production. Since the multi-piston pumps of the invention are preferably used in vehicles and are therefore mass-produced products, disposing the piston pumps parallel according to the invention results in potentially great cost reductions.
Also preferably, the first eccentric and the second eccentric are disposed rotated to one another at an angle. The angle is especially preferably approximately 150°.
To obtain an especially compact arrangement and to achieve the shortest possible line course in the housing of the multi-piston pump, the piston pumps of the first pump unit are disposed in a first half of the multi-piston pump, and the piston pumps of the second pump unit are disposed in a second half of the multi-piston pump.
The piston pumps of a pump unit are especially preferably disposed in one half in an angular range of approximately 120°. This makes for a very compact construction.
The invention is described in detail below in conjunction with the accompanying drawings. In the drawings:
A multi-piston pump 1 in an exemplary embodiment of the invention will be described below, referring to
The multi-piston pump 1 includes a housing 2, a first pump unit 3, and a second pump unit 4. The first pump unit 3 includes three piston pumps 3a, 3b, 3c, and the second pump unit 4 includes three piston pumps 4a, 4b, 4c. As can be seen particularly in
As can be seen from
Centrally in the middle of the housing 2, there is a recess 7 which serves to receive the first eccentric 5 and the second eccentric 6. A first low-pressure reservoir 8a and a second low-pressure reservoir 8b are also disposed in the housing 2. From the first low-pressure reservoir 8a, low-pressure lines lead to the first pump unit 3, and from the second low-pressure reservoir 8b, low-pressure lines lead to the second pump unit 4. As can be seen from
The same line lengths for the first and second pump units 3, 4 moreover assure that upon braking, no delay between the two brake circuits I and II occurs at the wheel brakes VR, HL and VL, HR, respectively.
The eccentric unit that includes the first and second eccentrics 5, 6 is disposed in the recess 7 and is driven by an electric motor, not shown. The electric motor can be mounted directly on the housing 2. The first eccentric 5 and the second eccentric 6 are disposed rotated by an angle of approximately 150° from one another (see
As can be seen from
Number | Date | Country | Kind |
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102005055057.6 | Nov 2005 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2006/067824 | 10/26/2006 | WO | 00 | 5/16/2008 |