Fluid-pressure and analogous brake systems – With pump
Reexamination Certificate
1999-05-06
2001-01-16
Butler, Douglas C. (Department: 3613)
Fluid-pressure and analogous brake systems
With pump
C303S116100, C303S116400
Reexamination Certificate
active
06174033
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and a device for forming and/or adapting a driving signal for driving a pump to deliver a pressurized medium of a braking system. Contained in the braking system under discussion are shut-off devices, in particular, valves for the inlet and/or outlet and/or passage of the pressurized medium, as well as, optionally, further means delivering the pressurized medium, in particular, optionally, at least one further pump for adjusting a pressure in the pressurized medium.
BACKGROUND INFORMATION
Conventional braking systems come in many variations. Such a braking system has at least one brake circuit, in which is arranged at least one means delivering the pressurized medium, particularly, in the case of a hydraulic braking system, for example, one pump which is also designated as a return pump. In addition, provision can optionally be made for at least one further means delivering the pressurized medium, in particular, a self-priming charging pump which is connected by an intake line to a reservoir for the pressurized medium. The inlet and outlet of the pressurized medium into and out of the brake circuit, in the same way as the inlet and outlet of the pressurized medium into and out of the respective wheel-brake cylinder, are controlled by way of shut-off devices, in particular, valves for the inlet and/or outlet and/or passage of the pressurized medium. This is described, for example, in German Patent No. 195 46 682. This arrangement is also found in principle in an electrohydraulic braking system, as described in German Patent No. 195 48 248, in which the pressurized medium is fed to the valves or comes from the valves through a pump via an interposed pressure reservoir. In that case, the pressurized medium is fed into or let out of the wheel-brake cylinders by opening and closing the intake and discharge valves according to the braking input of the driver and/or the driving signals of a mediating logic such as, for example, of an antilock braking system, a traction control system, or a dynamic movement control system.
Thus, the basic described arrangement is equally fulfilled, for example, in a hydraulic braking system by a return pump with intake and discharge valves or by a charging pump with charging and selector valves, just as, for example, in an electrohydraulic braking system by a storage pump with intake and discharge valves.
This basic design is also fulfilled in any comparable arrangement composed of a means for delivering the pressurized medium, and shut-off devices, which can be allocated to the means, for the inlet and/or outlet and/or passage of the pressurized medium in a braking system.
A pump of a braking system is often driven on the basis of the evaluation of the pump rotational frequency or the rotational frequency of the motor actuating the pump. In so doing, either the rotational frequency is directly ascertained, or a variable representing the rotational frequency is used. In this context, the known methods are aimed at the correlation between the pump rotational frequency and the volume of pressurized medium delivered. Therefore, the pump is driven in a manner compatible with the delivery rate. An exact adaptation of this delivery rate to specific pressure ranges in the braking system is described in German Patent No. 195 48 248. In that case, different pressure ranges are subdivided by a plurality of pressure thresholds, and the pump operates with a different delivery rate in each pressure range.
In this method, the pump is driven as a function of the delivery rate, to suit the needs, so to speak, i.e., the build-up or reduction of pressure in the braking system is predefined by the braking input of the driver and/or a logic which processes the input. Dependent upon this, on one hand, one or more pumps and, in addition, the corresponding valves are driven. At the same time, to reduce the noise, the pump is driven by a clocked signal.
It has turned out that the indicated methods and the corresponding devices are not able to furnish optimal results in every situation. An object of the present invention is, on one hand, to produce a good pressure build-up dynamic in the lower pressure range and the very flat pressure-volume characteristic curve of a braking hydraulic existing in that range, and, on the other hand, to achieve a further reduction in noise, especially at the high pressure level as well.
SUMMARY OF THE INVENTION
The dependence of the driving signal of the pump, or the formation of this driving signal, on the driving signal of at least one shut-off device, in particular, of at least one valve and/or the formation of this driving signal, makes it possible to exactly adjust the driving of the pump to the position of the shut-off device. The use of different pump delivery rates, adapted to the prevailing pressure ratios and the valve position, permits a further reduction in noise compared to the Related Art, since great pressure pulsations as are caused, for example, when the pressurized medium is delivered against closed valves or valves which are open in a manner not compatible with the delivery rate, can be avoided.
In using several means for delivering the pressurized medium, in particular at least one charging pump and at least one return pump for the brake circuit, a coordination of the driving of the means for delivering the pressurized medium can be carried out, including the position of the shut-off device. This permits the delivery rate to be more exactly adapted to the respective situation.
REFERENCES:
patent: 5197787 (1993-03-01), Matsuda et al.
patent: 195 04 295 (1995-08-01), None
patent: 195 27 805 (1996-03-01), None
patent: 195 35 623 (1996-04-01), None
patent: 195 46 682 (1997-06-01), None
patent: 195 48 248 (1997-06-01), None
patent: 196 10 863 (1997-09-01), None
Busch Gerd
Gerdes Manfred
Butler Douglas C.
Kenyon & Kenyon
Robert & Bosch GmbH
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