The present invention relates to a brake system for a vehicle, having a return pump situated in the brake circuit.
Various designs of brake systems for vehicles are known from the prior art. Usually, brake systems with two separate brake circuits are used. In addition, the brake circuits usually have regulating devices such as an antilock regulator or an electronic stability programming (ESP) regulator in order to improve the safety of the vehicle in various driving situations. Pumps are used to recirculate a hydraulic fluid in the brake circuit. Usually, at least one pump per brake circuit is provided for this.
The brake system for a vehicle according to the invention, with the defining characteristics of claim 1, has the advantage over the prior art of an improved delivery rate. This is achieved according to the invention in that the brake system includes a return device that includes at least one first pump device and one second pump device that are hydraulically connected in parallel. The first and second pump devices each have an inlet valve and an outlet valve directly connected to them. In addition, the first and second pump devices are operated with delivery cycles that are offset from each other in order to produce as constant as possible a delivery rate, without the occurrence of pulsations. In the context of the present invention, the expression “delivery cycles that are offset from each other” is understood to mean that for example, the first pump device is in the suction phase while the second pump device is in the compression phase. Naturally, it is also possible to embody the offset delivery cycle so that the same phases can partially overlap each other. Also according to the invention, an additional valve is now situated in each intake line of each pump device. This additional valve prevents a negative pressure that is generated during the suction phase of one of the pump devices from also prevailing in an intake line of a second pump device. Consequently, the present invention makes it possible to operate two, three, or more pump devices in parallel with one another, without the occurrence of disadvantageous effects due to the respective offset delivery cycles of the individual pump devices. Consequently, overlaps of the pump devices can occur in the respective suction phase, without one of the pump devices being subjected to an unwanted negative pressure. This makes it possible to achieve a higher delivery rate and also to improve a conveyance of the intake flow, particularly in a shared intake line of the pump devices, which reduces the losses that occur. Consequently, the return device according to the invention is able to achieve an improved efficiency. The embodiment according to the invention is particularly simple and can be produced very inexpensively.
Preferred modifications of the invention are disclosed in the dependent claims.
In order to be able to achieve a particularly simple embodiment and a particularly inexpensive design, the additional valve is embodied in the form of a check valve without a spring. Consequently, a non-prestressed check valve is used, which is opened and closed only by the medium. Valves of this kind are also very low-maintenance.
It is also preferable if a line volume of a line segment situated between an additional valve and an inlet valve of a first pump device is approximately equal to a volume to be taken in by a second pump device is that is currently in the suction phase. This makes it possible to assure that a necessary fluid quantity of the first pump device, which is currently at the beginning of its suction phase, can be drawn from the existing line volume with no trouble until the second pump device has completed its intake procedure.
It is particularly preferable if a line volume between an additional valve and an inlet valve of a pump device is greater than or equal to a total filling volume of a pump device. This makes it possible for the entire intake quantity to be drawn from the line volume.
Preferably, three pump devices are situated in one brake circuit.
In another preferred embodiment, a pump device is a pump element of a radial piston pump. If three pump elements of a radial piston pump are provided as a return device, then they can be operated in delivery cycles that are offset from one another by a rotation angle of 120°. The pump elements here can be situated resting against one or two eccentric arrangements, with the suction phase of one pump element corresponding to a 180° rotation angle. The use of a radial piston pump with three pump elements as a delivery device permits a particularly compact and simple design.
Preferably, the brake system includes a first and second brake circuit, with at least one first and second pump device situated each brake circuit.
Alternatively, the return device can also be comprised of three separate pumps situated parallel to one another.
A preferred exemplary embodiment of the invention will be described in detail below in conjunction with the accompanying drawings.
An exemplary embodiment of a brake system 1 according to the invention will be described below in conjunction with
As is particularly clear from
As is clear from
As is particularly clear from
Number | Date | Country | Kind |
---|---|---|---|
10 2005 057 301.0 | Dec 2005 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/EP2006/067893 | 10/27/2006 | WO | 00 | 5/20/2008 |