US-12623647-B2 - Braking system, and valve with activatable holding force

US12623647B2US 12623647 B2US12623647 B2US 12623647B2US-12623647-B2

Abstract

A brake system may include at least two wheel brake cylinder of separate wheel circuits, at least one pressure supply to provide pressure in the wheel brake cylinders, at least one reservoir, at least one electronic control and regulating unit, and switching valves arranged to connect and disconnect respective hydraulic lines connected to the respective wheel brake cylinders to/from at least one main hydraulic line coupled to the pressure supply(s). Leakage diagnostics of the individual wheel circuits and/or other components of the brake system may be carried out. The switching valves may include an electromagnetic drive and a force-adding device for operation of the valves.

Inventors

Heinz Leiber
Anton van Zanten

Assignees

IPGATE AG

Dates

Publication Date: 20260512
Application Date: 20220823
Priority Date: 20210909

Claims (20)

1 . A brake system including: at least two wheel brake cylinders, which are each part of separate wheel circuits, respective hydraulic connection lines connected to respective ones of the at least two wheel brake cylinders and also forming parts of respective ones of the separate wheel circuits, at least one pressure supply, which serves at least to build up pressure in the at least two wheel brake cylinders, at least one reservoir, at least one electronic control and regulating unit, switching valves, wherein each of the at least two wheel brake cylinders is connected via its respective hydraulic connecting line to a respective one of the switching valves, which serves to disconnect and connect the respective hydraulic connection of the respective wheel brake cylinder and at least one further hydraulic main line, via which the respective switching valve is enabled to be connected at least to the at least one pressure supply, wherein diagnoses of respective leakages of the individual wheel circuits are carried out, and wherein, depending on the diagnostic results, an electronic control and regulating unit of the at least one electronic control and regulating unit decides whether a given wheel circuit is switched off by permanently closing the associated switching valve of the given wheel circuit or continues to be operated to generate a braking effect.
2 . The brake system according to claim 1 , wherein a degree of leakage or a leakage flow in a respective one of the wheel circuits is determined using one or more of the following methods a) to e): a) determination of a required quantity of hydraulic fluid which must be supplied in addition to a predetermined quantity of fluid by means of the at least one pressure supply in order to achieve a set pressure in the respective wheel circuit; b) determination of a determined absolute pressure drop and/or pressure drop gradient in the respective wheel circuit; c) determination of a pressure deviation from a target pressure value during pressure build-up in the respective wheel circuit, in that a predetermined quantity of fluid is conveyed into the wheel circuit to achieve the target pressure and an actual pressure is then determined; d) diagnosing leakage in the respective wheel circuit by measuring pressure over time in the hydraulic main line connecting the switching valve of the respective wheel circuit and the at least one pressure supply during pressure build-up by means of the at least one pressure supply or when the at least one pressure supply is switched off; or e) measurement of an intake volume of the respective wheel circuit via the at least one pressure supply to achieve a target pressure, the intake volume being determined by means of the at least one pressure supply via current measurement of a drive motor of a pressure supply of the at least one pressure supply and/or the piston travel of a piston of the pressure supply of the at least one pressure supply.
3 . The brake system according to claim 1 , wherein when an upper limit value or limit value range of a leakage of a given wheel circuit is exceeded, the respective associated switching valve of the given wheel circuit is permanently closed, and wherein below the upper limit value and above a lower limit value a time-limited and/or permanent additional delivery takes place to achieve a brake pressure to be set in the respective wheel brake cylinder of the given wheel circuit.
4 . The brake system according to claim 3 , where that the upper limit value is determined by a maximum delivery rate of the at least one pressure supply for increasing the brake pressure in the given wheel circuit.
5 . The brake system according to claim 4 , wherein, in the event of a leakage flow of 50-90% of a maximum delivery capacity of the at least one pressure supply, the leakage flow is compensated by means of the at least one pressure supply by means of additional delivery.
6 . The brake system according to claim 3 , wherein, in order to optimize braking effect and driving stability, an electronic control and regulating unit of the at least one electronic control and regulating unit determines whether and which leaking wheel circuit(s) is/are switched off by permanently closing the respective switching valve(s) associated with the leaking wheel circuit(s).
7 . The brake system according to claim 1 , wherein an exhaust valve belonging to a wheel brake cylinder is a component of the respective wheel circuit that includes the wheel brake cylinder.
8 . The brake system according to claim 1 , wherein the brake system further includes a brake pedal acting mechanically on a master brake cylinder or an electronic brake pedal for a brake-by-wire brake system.
9 . The brake system according to claim 1 , wherein single faults, double faults and a leakage rate in the brake system are detected by means of the diagnoses.
10 . The brake system according to claim 1 , wherein no non-return valves are connected in parallel with the respective switching valve.
11 . The brake system according to claim 1 , wherein when a certain leakage flow in at least one wheel circuit or a sum of all determined leakage flows is exceeded, the brake system emits a warning message that at least one of the wheel circuits has failed.
12 . The brake system according to claim 1 , wherein a pressure-volume characteristic of a respective wheel circuit is taken into account in diagnosing a leak in the respective wheel circuit.
13 . The brake system according to claim 1 , further including a maximum of two further switching valves arranged in the respective hydraulic connecting line between the pressure supply and a given one of the switching valves.
14 . The brake system according to claim 1 , further including one or two first further switching valves disposed in the hydraulic switching line associated with a respective one of the switching valves associated with a respective one of the wheel circuit between the at least one pressure supply and the respective one of the switching valves of, and wherein only one of the first further switching valves is arranged in the hydraulic connecting line between the at least one pressure supply and at least one second further switching valve of another one of the wheel circuits.
15 . The brake system according to claim 1 , wherein all wheel circuits belong to one brake circuit and are connected via a common hydraulic main line either: a) to a single working chamber of a plunger system of the at least one pressure supply or are separable from the working chamber via at least one valve, or b) are connected or are connectable to both working chambers of a double-acting piston-cylinder system of the at least one pressure supply whereby a pressure reduction and/or pressure build-up is enabled to take place in at least one wheel circuit in both stroke directions of the double-acting piston.
16 . The brake system according to claim 1 , wherein two of the wheel circuits belong to a given brake circuit wherein the given brake circuit includes a hydraulic brake circuit lines.
17 . The brake system according to claim 16 , wherein the brake system includes two brake circuits enabled to be hydraulically connected to one another or hydraulically separated from one another via a circuit separation valve.
18 . The brake system according to claim 17 , wherein each brake circuit is connected or is enabled to be connected via a separate hydraulic line to a respective working chamber of a double-acting piston-cylinder system of the at least one pressure supply.
19 . The brake system according to claim 7 , wherein at least one of the at least two wheel brake cylinders, is assigned an exhaust valve or only one single exhaust valve is provided for the brake system.
20 . The brake system according to claim 15 , wherein at least one of the wheel brake cylinders is or are each assigned an exhaust valve.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a Section 371 of International Application No. PCT/EP2022/073463, filed Aug. 23, 2022, which was published in the German language on Mar. 16, 2023 under International Publication No. WO 2023/036607 A1, which claims priority under 35 U.S.C. § 119(b) to German Patent Application No. 20 2021 105 878.1, filed Sep. 9, 2021, the disclosures of which are incorporated herein by reference. STATE OF THE ART For almost 80 years, today's 2-circuit brake system with two brake circuits has become established for safety reasons and, depending on the vehicle design, is used in a brake circuit layout of a) diagonal andb) black/white or front axle/rear axle applied. In the event of a brake circuit failure, the braking effect is reduced by 50% for a) and by up to approx. 70% for b). In the statistics, 10 ppm/J is calculated for a brake circuit failure. Due to the reduced braking effect or total brake failure, there is a considerable risk of accidents. DE 10 20 2018 213 306 describes a system with detection of brake circuit failure due to leakage in the brake circuit by evaluating the pressure gradient. Almost all vehicles have electronic brake control systems for all four vehicle wheels, which are usually hydraulically braked. Each wheel brake cylinder is connected to at least one or two electromagnetically controlled control valves, which are electrically controlled by an electrical control unit (ECU), e.g. to prevent the wheel from locking. In today's standard brake systems with ABS/ESP function, each wheel brake cylinder is usually assigned an inlet and an outlet valve, whereby the inlet valve usually has a non-return valve connected in parallel so that the inlet valve, which is often also referred to as the switching valve, does not close due to the back pressure when the pressure is reduced quickly. If an inlet valve with its associated non-return valve fails and leaks, an entire brake circuit usually fails in today's 2-circuit brake systems if the wheel brake cylinder fails, reducing the braking effect by at least 30%. Object of the Invention The object of the invention is to prevent the failure of an entire brake circuit if only one wheel circuit fails or leaks. By wheel circuit is meant here the wheel brake cylinder including its hydraulic connection to the valve, e.g. inlet valve, up to the wheel brake cylinder. Four-circuit brake system is understood here as a brake system in which, if one wheel circuit or two or three wheel circuits fail, the other three or two wheel circuits or one wheel circuit are still functional. Advantages of the Invention In order to achieve the above, as few failing components as possible must be used between the pressure feed, in the line connection to the output of the hydraulic control unit. These include, for example, solenoid or mechanically actuated valves. Ultimately, it is crucial that only a single valve in the “normally de-energized open” configuration is used at the end of the line connection from the pressure feed to the respective wheel brake cylinder. An inlet valve commonly used for ABS/ESP has a parallel non-return valve, which is considered unsafe in terms of tightness and can no longer be used. As described above, the non-return valve was provided so that the inlet valve does not close due to back pressure during rapid pressure reduction. The valve SV2k according to the invention is understood to be the valve assigned to a wheel brake cylinder, via which hydraulic medium flows to build up pressure in only this wheel brake cylinder. The wheel circuit is then understood here as the wheel brake cylinder including the hydraulic connection from the valve to the wheel brake cylinder. Of course, the hydraulic medium can also flow from the associated wheel brake cylinder through the valve SV2k back into the brake circuit BK1 or BK2 to reduce the pressure. To avoid the problems described above, the invention uses a valve SV2k or a switching valve of the “normally de-energized open” type, the valve actuator of which is moved by means of a first electromagnetic actuator from the open valve position to the closed valve position, in which the valve actuator is pressed against a valve seat. If the electromagnetic actuator is not or not sufficiently energized, a valve spring presses the valve actuator into the initial position, i.e. into the open valve position. In the open valve position, the invention provides an additional force device that generates an additional force on the valve actuator, which is directed in the direction of the open valve position and thus supports or replaces the valve spring, resulting in an increased resultant force with which the valve actuator is force-loaded into the open valve position. The additional force device can be switchable, e.g. formed by an additional electromagnet to the actual valve actuator. It can therefore also be described as an active additional force device, as the additional fo