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DE-102014215030-B4 - Hydraulic braking system with high-pressure switching valve

DE102014215030B4DE 102014215030 B4DE102014215030 B4DE 102014215030B4DE-102014215030-B4

Abstract

Hydraulic brake system (200) for a vehicle with at least one brake circuit (201), comprising an actuating device (202) configured to generate brake pressure in a main brake line (203) filled with hydraulic fluid when actuated, comprising an electrically controlled inlet valve (204) connected to the main brake line (203) on the inlet side and configured to direct brake pressure to a wheel brake line (205) on the outlet side, comprising a wheel brake (206) with a hydraulic brake cylinder (207) connected to the wheel brake line (205) and configured to brake a wheel of the vehicle depending on the brake pressure in the wheel brake line (205), comprising an electrically controlled outlet valve (208) configured to direct hydraulic fluid from the wheel brake line (205) into a storage chamber (209), and comprising an electrically controlled high-pressure switching valve (211) which is configured to direct hydraulic fluid from the storage chamber (209) back into the main brake line (203) via a check valve (212) arranged upstream of the high-pressure switching valve (211), characterized in that the high-pressure switching valve (211) is designed as a high-pressure resistant switching valve with an electrically switchable locking position and is in an open position in the rest state, in which a return of hydraulic fluid from the storage chamber (209) back into the main brake line (203) can be achieved.

Inventors

  • Andreas Zoebele
  • Matthias Kranich

Assignees

  • ROBERT BOSCH GMBH

Dates

Publication Date
20260513
Application Date
20140731

Claims (10)

  1. Hydraulic brake system (200) for a vehicle with at least one brake circuit (201), comprising an actuating device (202) configured to generate brake pressure in a main brake line (203) filled with hydraulic fluid when actuated, comprising an electrically controlled inlet valve (204) connected to the main brake line (203) on the inlet side and configured to direct brake pressure to a wheel brake line (205) on the outlet side, comprising a wheel brake (206) with a hydraulic brake cylinder (207) connected to the wheel brake line (205) and configured to brake a wheel of the vehicle depending on the brake pressure in the wheel brake line (205), comprising an electrically controlled outlet valve (208) configured to direct hydraulic fluid from the wheel brake line (205) into a storage chamber (209), and comprising an electrically controlled high-pressure switching valve (211) which is configured to direct hydraulic fluid from the storage chamber (209) back into the main brake line (203) via a check valve (212) arranged upstream of the high-pressure switching valve (211), characterized in that the high-pressure switching valve (211) is designed as a high-pressure resistant switching valve with an electrically switchable locking position and is in an open position in the rest state, in which a return of hydraulic fluid from the storage chamber (209) back into the main brake line (203) can be achieved.
  2. Hydraulic braking system (200) according to Claim 1 , characterized in that the brake device (200) has a return pumping device for conveying hydraulic fluid from the storage chamber (209) back into the main brake line (203), wherein the return pumping device comprises a motor-pump unit (217) and a changeover valve (215), the changeover valve (215) being arranged in the main brake line (203) between the actuating device (202) and the at least one inlet valve (204) such that the main brake line is divided into two sections, wherein the changeover valve (215) is open to hydraulic fluid in a rest state towards the at least one inlet valve (204) and in a reverse state towards the actuating device (202), and wherein the motor-pump unit (217) is configured to pump hydraulic fluid from the storage chamber (209) into the section of the main brake line (203) between the changeover valve (215) and the inlet valve (204), and the braking device (200) is arranged such that during pumping of the motor-pump unit (217) the switching valve (215) is in the reverse state and the high-pressure switching valve (211) is in the locked state.
  3. Hydraulic braking system (200) according to Claim 2 , characterized in that the braking device (200) has a control device, and that the electrically controlled inlet valve (204), the electrically controlled outlet valve (208), the electrically controlled changeover valve (215) and the motor-pump unit (217) can be controlled by the control device during a control process, in particular an ABS control, and the braking device (200) is arranged such that the high-pressure switching valve (211) is closed during a control process.
  4. Hydraulic braking system (200) according to Claim 3 , characterized in that the braking device (200) is configured such that the high-pressure switching valve (211) is open immediately after a control process.
  5. Hydraulic braking system (200) according to Claim 4 , characterized in that the brake device (200) is arranged such that the high-pressure switching valve (211) is open when the brake pressure can be achieved by the actuating device (202) but is insufficient to trigger a control process, and a backflow of the hydraulic fluid from the main brake line (203) into the storage chamber (209) can be prevented by the check valve (212).
  6. Method for emptying a storage chamber (209) of a hydraulic brake system (200) of a vehicle, wherein the brake system (200) has an actuating device (202) which, when actuated, is configured to generate a brake pressure in a main brake line (203) filled with hydraulic fluid, which has an electrically controlled inlet valve (204) which is connected on the inlet side to the main brake line (203) and is configured to direct a brake pressure on the outlet side to a wheel brake line (205), which has a wheel brake (206) with a hydraulic brake cylinder (207) which is connected to the wheel brake line (205) and is configured to brake a wheel of the vehicle depending on the brake pressure in the wheel brake line (205), which further has an electrically controlled outlet valve (208) which is configured to direct hydraulic fluid from the wheel brake line (205) into a storage chamber (209), and which has an electrically controllable high-pressure switching valve (211) which is designed to drain hydraulic fluid from the storage chamber (209) back into the main brake line (203) through a check valve (212) arranged upstream of the high-pressure switching valve (211), characterized in that the high-pressure switching valve (211) is designed as a high-pressure resistant switching valve with an electrically switchable locking position and in an open rest position the storage chamber (209) is drained into the main brake line (203).
  7. Procedure according to Claim 6 , wherein the brake device (200) comprises a motor-pump unit (217) and a changeover valve (215), the changeover valve (215) being arranged in the main brake line (203) and dividing it between the actuating device (202) and the at least one inlet valve (204), and wherein the motor-pump unit (217) is configured to pump hydraulic fluid from the storage chamber (209) into the part of the main brake line (203) between the changeover valve (215) and the inlet valve (204), characterized in that the high-pressure switching valve (211) closes for the duration of a pumping operation of the motor-pump unit (217).
  8. Procedure according to Claim 7 , characterized in that the high-pressure switching valve (211) is open outside of a pumping process and pre-fills a connection chamber between the high-pressure switching valve (211), check valve (212) and motor-pump unit (217) with hydraulic fluid through the open high-pressure switching valve (211).
  9. Procedure according to Claim 6 , characterized in that the electrically controlled inlet valve (204), the electrically controlled outlet valve (208), the electrically controlled switching valve (215) and the motor-pump unit (217) are controlled by an electrical control device to carry out a control process, wherein the high-pressure switching valve (211) is closed for the duration of this control process.
  10. Procedure according to Claim 9 , characterized in that the high-pressure switching valve (211) is closed exclusively for the duration of a control process, so that the storage chamber (209) otherwise empties via the high-pressure switching valve (211).

Description

The invention relates to a hydraulic braking system for a vehicle. State of the art Modern hydraulic braking systems for vehicles, especially motor vehicles, typically incorporate control devices such as anti-lock braking systems (ABS), traction control systems (ASR), or vehicle dynamics control systems (ESP, Electronic Stability Program). These control devices usually require an accumulator chamber as a temporary reservoir for hydraulic fluid. When one of the control devices is activated, i.e., when a control event occurs, the accumulator chamber fills. The subsequent emptying of the accumulator chamber is usually accompanied by a noise that is perceptible to the driver. 1 Figure 1 shows an example of a state-of-the-art braking system 100. For safety reasons, the braking system 100 has two separate, essentially symmetrical hydraulic brake circuits 101 containing hydraulic fluid. Depending on the vehicle manufacturer, one brake circuit 101 typically brakes one wheel on the front axle and one diagonally opposite wheel on the rear axle (X-split), or one brake circuit 101 brakes the wheels of the front axle and the other the wheels of the rear axle (II-split). The braking system 100 comprises an actuating device 102 (e.g., foot pedal) common to both brake circuits 101, with a brake booster 118 and a reservoir 120, as well as a master brake cylinder 119 with several valves for adjusting individual wheel brake pressure for each brake circuit 101. Unless otherwise stated, the following description applies equally to both brake circuits 101. When the brake device 100 is actuated, brake pressure is generated in a main brake line 103, which acts on the brake cylinders 107 of the wheel brakes 106 via a changeover valve 115 and an inlet valve 104 for each wheel. In the event of emergency braking, the brake pressure acting on the brake cylinder 107 of the wheel brakes 106 can be reduced by selectively and intermittently opening and closing the inlet valve 104 and a corresponding outlet valve 108, for example by means of the control of an anti-lock braking system (ABS). The hydraulic fluid escaping from the main brake line 103 via the outlet valves 108 is buffered in a storage chamber 109 and, during ABS operation, is returned to the main brake line 103 via a return pump unit, typically a motor-pump unit 117, and the changeover valve 115, which is switched to the reverse pressure direction. Furthermore, the hydraulic fluid in the storage chamber 109 can be used via the motor-pump unit 117 to generate a brake pressure in the main brake line 103 that exceeds the brake pressure requested by the driver, for example, to initiate or intensify braking using a brake assist system (BAS) or vehicle dynamics controller (VDC). To determine the aforementioned brake pressure requested by the driver, one of the two brake circuits 101 has a brake sensor 116. The reservoir chamber 109 can be emptied outside of ABS control either via an audible overrun of the motor-pump unit 117 or, alternatively, via high-pressure switching valves 110. According to the state of the art, the high-pressure switching valves 110 are designed as high-pressure-resistant switching valves with an electromagnetically switchable open position. If the brake sensor 116 does not detect the brake pressure desired by the driver, the high-pressure switching valves 110 are opened to return the hydraulic fluid to the main brake line 103. The switching noise of the high-pressure switching valves 110 is also audible to the driver when the vehicle is stationary or in low ambient noise conditions. Therefore, both of the aforementioned options for emptying the reservoir chamber 109 are associated with noises that are perceptible to the driver and may cause irritation. The printed matter DE 10 2008 002 244 A1 It uses a pressure-reducing valve, which otherwise remains closed, to drain brake fluid from a low-pressure reservoir of a vehicle in a braking system state where the wheel brakes are depressurized. The printed matter DE 10 2013 202 789 A1 This describes a method and a system for controlling a braking system for a motor vehicle that has an electro-regenerative brake and hydraulic wheel brakes. In the known system, during a braking process in which the hydraulic pump is used to generate pressure, a vacuum can occur on the suction side of the pump in one of the brake circuits if the associated low-pressure accumulator is emptied. Disclosure of the invention The object of the present invention is to provide a simple hydraulic braking device in which the emptying of an intermediate storage reservoir for hydraulic fluid is barely perceptible to the driver acoustically. The problem is solved according to the invention by the features of the independent claims. Advantageous embodiments of the invention are specified in the dependent claims. According to the invention, a hydraulic brake device for a vehicle with at least one brake circuit is provided, comprising an actuating devi