Brake system with bypass line and motor vehicle

Abstract

The invention relates to a brake system (1) for a motor vehicle (2), having a plurality of brake devices (3) for braking the wheels (4) of the motor vehicle, respectively, a brake fluid pump (5) for generating a brake pressure for operating the brake devices, the brake fluid pump having a pump inlet (8) which is coupled in fluid connection with a brake fluid reservoir (7), and a pump outlet (9) which is coupled in fluid connection with the brake devices, a control device (6) for controlling the brake fluid pump, and a bypass line (11) which can be actuated by a bypass valve (10) for pumping brake fluid from the brake fluid pump, without passing through the brake devices, into the brake fluid reservoir, the bypass valve having a bypass position and a normal operating position. The invention also relates to a motor vehicle having a brake system according to the invention.

Description

Technical Field

[0001] This invention relates to a braking system for a motor vehicle. It also relates to a motor vehicle having a braking system of the type described herein. Background Technology

[0002] A known braking system mechanically decouples the braking device for braking the wheels of a motor vehicle from the operating device for transmitting braking commands, such as the brake pedal. In this system, the braking command can be transmitted as an electrical signal to the brake fluid pump to operate the braking device. Because the braking command cannot be mechanically transmitted but can be transmitted via a data cable, this type of braking system is also called "brake-by-wire." A disadvantage of brake-by-wire systems is that, in the event of a malfunction, the required braking pressure cannot be achieved due to the increased operating pressure of the brake pedal.

[0003] The viscosity of brake fluid depends on several factors. At relatively low temperatures, brake fluid has a higher viscosity. This effect is also enhanced by the aging of the brake fluid, as it develops a higher water content with age. The operational safety of the braking system cannot be guaranteed at critical viscosity values, which may occur, for example, in extremely cold conditions.

[0004] The suction characteristics of the brake fluid pump deteriorate with increasing viscosity, thus prolonging the time required to reach the preset braking pressure. This negatively impacts the braking characteristics of the vehicle, as braking is delayed due to the increased viscosity of the brake fluid. This effect is particularly relevant to brake-by-wire systems due to the mechanical decoupling between the operating mechanism and the braking device.

[0005] During the suction process of the brake fluid pump, local pressure fluctuations may occur in the suction area of ​​the brake fluid pump, such as in the suction line. These pressure fluctuations may damage the brake fluid pump, control valve, or brake fluid line due to various physical effects, such as cavitation.

[0006] A conventional braking system is known from document DE 100 27 147A1. This system is designed to pump brake fluid to the braking device via an ABS pump for a predefined period of time when the vehicle's motor is started at low external temperatures, such as in frigid conditions, thereby generating braking pressure. The brake fluid can thus be heated, and its viscosity can be reduced. A disadvantage of this braking system is that the vehicle cannot move during this preheating process. Furthermore, the resulting operation of the braking device, especially in frigid conditions, may cause the brake pads to undesirably adhere to the cold and potentially icy brake discs. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is to eliminate, or at least partially eliminate, the aforementioned disadvantages in braking systems for motor vehicles. In particular, the technical problem to be solved by the present invention is to provide a braking system and a motor vehicle that ensures better heating of the brake fluid at temperatures below freezing in a simple and cost-effective manner, thereby avoiding excessively high viscosity of the brake fluid and avoiding the negative braking characteristics associated with the braking device.

[0008] The aforementioned technical problem is solved according to the present invention by a braking system for a motor vehicle and a motor vehicle. Other technical features and details of the invention are derived from the specification and drawings. Herein, the features and details described in relation to the braking system according to the invention are of course also applicable to the motor vehicle according to the invention, and vice versa; therefore, the disclosure of each individual aspect of the invention is always alternately referred to or can be alternately referred to.

[0009] The technical problem described herein is solved by a braking system for a motor vehicle according to a first aspect of the invention. The braking system includes a plurality of braking devices, a brake fluid pump, a control device for controlling the brake fluid pump, and a brake fluid reservoir for containing brake fluid. These braking devices are used to brake the wheels of a motor vehicle (or, one wheel of each vehicle), and the brake fluid pump is used to generate braking pressure for operating the braking devices. The brake fluid pump has a pump inlet and a pump outlet, the pump inlet being fluidly coupled to the brake fluid reservoir, and the pump outlet being fluidly coupled to the braking devices. According to the invention, the braking system has a bypass line operable by a bypass valve for pumping brake fluid from the brake fluid pump to the brake fluid reservoir without passing through the braking devices, wherein the bypass valve has a bypass position and a normal operating position.

[0010] The braking system is preferably designed as a brake-by-wire braking system. Therefore, the braking system preferably does not have a mechanical coupling between the brake pedal and the braking device. The braking system is preferably designed for operating each individual braking device separately. Thus, the (multiple) braking devices can preferably be loaded with brake fluid independently of each other. The fluid communication coupling between two devices is understood within the scope of this invention as a design that directs the flow of brake fluid from one device to the next. Here, the fluid flow can, if necessary, be released, locked, accelerated, or braked via any valves, throttles, pumps, or similar components.

[0011] The braking device is preferably constructed according to a known disc brake. Therefore, the braking device preferably includes a brake disc, a brake caliper partially surrounding the brake disc, two brake pads movably arranged on the brake caliper for clamping the brake disc on both sides, a brake cylinder that can be loaded with brake fluid to move the brake pads to the brake disc, and a return device for moving the brake pads away from the brake disc. The return device can, for example, be integrated within the brake cylinder. Alternatively, the braking device can be designed entirely or partially as a drum brake. The braking system preferably has a braking device for each wheel of the motor vehicle. Therefore, the braking system preferably has four braking devices. These braking devices are preferably coupled in fluid communication with a brake fluid pump via brake fluid lines.

[0012] The braking system includes a brake fluid pump for delivering brake fluid and generating brake fluid pressure. The brake fluid pump has a pump inlet, which can also be referred to as a suction pipe. The pump inlet is fluidly coupled to a brake fluid reservoir. During operation, brake fluid, preferably a polyethylene glycol compound or the like, disposed in the brake fluid reservoir, is drawn into the brake fluid pump through the pump inlet and discharged from the brake fluid pump through its outlet. The brake fluid pump preferably has a separate outlet for each braking device or a common outlet, which is fluidly coupled to the braking devices via a distributor. The braking system preferably has individually operable valves on each brake fluid line, allowing brake fluid to be selectively directed to the appropriate braking device for braking the wheels as defined.

[0013] The control device is designed to control the brake fluid pump and bypass valve, and preferably to control other valves that may be present, so as to selectively load individual brake fluid lines with brake fluid. The control device is preferably designed to control the loading of brake fluid onto individual brake units during braking, thereby selectively preventing or at least reducing slippage of one or more wheels. The brake units are preferably designed and configured to control the loading of brake fluid onto individual brake units during braking, thereby selectively preventing or at least reducing vehicle derailment. The control device is preferably designed to operate the brake fluid pump according to the temperature and / or viscosity of the brake fluid. At particularly low temperatures or particularly high viscosities of the brake fluid, the brake fluid pump may, for example, start operating more slowly than during normal operation at higher temperatures or lower viscosities. For this purpose, the braking system preferably has temperature and / or pressure sensors. This slower start-up operation of the brake fluid pump is particularly advantageous for open bypass lines. The control device is preferably designed to detect one or more triggered events, such as a transponder approaching the vehicle, unlocking the vehicle, or operation for preheating. The system includes switching on / off the brake fluid, activating the vehicle's onboard electronics, starting the vehicle's drive motor, and, depending on the presence of the first or more of the aforementioned events, implementing targeted preheating of the brake fluid when using a bypass line.

[0014] The brake fluid reservoir is designed to hold brake fluid. The pump inlet is preferably directly and fluidly coupled to the brake fluid reservoir via a brake fluid line. The brake fluid line of the braking device is preferably fluidly coupled to the brake fluid reservoir so that brake fluid can be guided from the brake fluid line to the brake fluid reservoir. The brake fluid line preferably extends into the brake fluid reservoir in such a way that brake fluid is ensured to be drawn into the brake fluid pump even under high longitudinal acceleration, such as when driving on mountain roads, during acceleration or braking, and under high lateral acceleration, such as when driving at high speeds in corners.

[0015] The bypass valve is preferably arranged on the pump outlet, or, in the case of multiple pump outlets, on at least one of the multiple pump outlets. According to the invention, in the case of multiple pump outlets, bypass valves may be arranged on each of the multiple or all pump outlets. The bypass valve is preferably designed to release (or open) the brake fluid flow through the bypass line in the bypass position, and to at least restrict the brake fluid flow through the bypass line in the normal operating position. The bypass valve is also preferably designed to at least so restrict the brake fluid flow through the braking device in the bypass position that the braking device does not generate braking torque or only generates a small braking torque that allows the vehicle to move.

[0016] According to the invention, a bypass line can be provided for each bypass valve. Alternatively, for example, only one bypass line may be provided. The bypass line preferably leads directly to the brake fluid reservoir. The bypass line preferably leads to the brake fluid reservoir in such a way that brake fluid flowing through the bypass line flows into the brake fluid reservoir before it may flow to the braking device of the braking system. Alternatively, the bypass line may also lead to the pump inlet or at least to a brake fluid line extending from the brake fluid reservoir to the brake fluid pump, particularly adjacent to the brake fluid reservoir, thereby ensuring direct circulation of brake fluid through the brake fluid pump, the bypass line, and, if necessary, one or more additional brake fluid lines.

[0017] The braking system according to the invention has the advantage over conventional braking systems in that it ensures simple and efficient preheating of the brake fluid, especially in cold weather, through simple components and a cost-effective method. By connecting a bypass line and thereby avoiding or at least significantly reducing the load of the brake fluid on the braking device, the brake fluid can be preheated even when the vehicle is already in motion, without the braking device braking or locking one or more wheels. In this way, the wear, durability, and operational safety of the braking system can be greatly improved compared to known braking systems.

[0018] According to a preferred embodiment of the invention, the bypass valve in the braking system is designed to allow the flow of brake fluid from the pump outlet to the bypass line in the bypass position, and to prevent the flow of brake fluid from the pump outlet to the bypass line in the normal operating position. Thus, the bypass valve can be operated by means of a control device so that at least a portion of the brake fluid can be conveyed through the bypass line in the bypass position. Preferably, in the bypass position, only such brake fluid flow can reach the braking device, so that the braking device provides little or no braking force. This has the advantage of allowing improved preheating of the braking line and braking device. Furthermore, the bypass valve can be operated by means of a control device so that no brake fluid is guided through the bypass line in the normal operating position. Thus, the brake fluid pressure generated by the brake fluid pump can be fully utilized to operate the braking device. This has the advantage of simple and efficient preheating of the brake fluid, especially in cold weather, through simple devices and inexpensive methods. Furthermore, this further improves the wear, durability, and operational safety of the braking system.

[0019] According to a preferred embodiment of the invention, the bypass valve is designed to prevent the transfer of brake fluid from the pump outlet to the braking device in the bypass position, and to allow the transfer of brake fluid from the pump outlet to the braking device in the normal operating position. This ensures that no brake fluid is applied to the braking device while the brake fluid is being preheated in the bypass position. This avoids potentially unwanted braking of the wheels in this state. The advantage of this is that it improves the simple and efficient preheating of the brake fluid, especially in cold weather, through simple components and inexpensive methods. Furthermore, this further improves the wear resistance, durability, and operational safety of the braking system.

[0020] Preferably, the bypass line is positioned close to the heating device of the vehicle to facilitate heat exchange. A heat exchanger is preferably provided within this area to transfer heat from the heating device to the brake fluid in the bypass line. The bypass line preferably contacts the heating device or is introduced into the heating device. Alternatively or additionally, according to the invention, the bypass line may be positioned close to or in contact with an auxiliary device that can be heated by the heating device. The bypass line preferably has a material with particularly high thermal conductivity, such as a metal, preferably copper or aluminum, in the area of ​​the heating device and / or auxiliary device to improve heat transfer to the brake fluid. The control device is preferably designed to detect the operating status of the heating device and control the preheating process of the brake fluid through the bypass line based on the detected operating status. This has the advantage of improving the simple and efficient preheating of the brake fluid, especially in cold weather, with simple devices and inexpensive methods. Furthermore, this further improves the wear, durability, and operational safety of the braking system.

[0021] In a particularly preferred embodiment of the invention, the heating device for the braking system can be designed as a battery preheating device for the motor vehicle. In this case, the additional device is designed as a battery, particularly as a traction battery for supplying the electric motor to drive the motor vehicle. Preheating the motor vehicle battery is preferred at lower sub-zero temperatures to improve battery efficiency and prevent battery damage. The heating device is preferably designed to provide additional heat to improve the preheating of the brake fluid, thereby also ensuring the prescribed preheating of the battery. The bypass line can be designed according to the invention to achieve heat transfer from the battery preheating device directly and / or via a heat exchanger and / or via the battery to the brake fluid. This has the advantage of improving the simple and efficient preheating of the brake fluid, especially in cold weather, with simple devices and in a cost-effective manner. Furthermore, this further improves the wear, durability, and operational safety of the braking system.

[0022] Preferably, a throttle valve and / or pressure valve are arranged on the bypass line. The throttle valve and / or pressure valve are preferably provided additionally to the bypass valve. Alternatively or additionally, the throttle valve and / or pressure valve can be designed to be integrated into the bypass valve. This increases friction during brake fluid reflux, thereby accelerating brake fluid preheating. The advantage of this is that it improves the simple and efficient preheating of brake fluid, especially in cold conditions, through simple devices and inexpensive methods. Furthermore, this further improves the wear, durability, and operational safety of the braking system.

[0023] In a preferred embodiment of the invention, the control device is designed to adjust the bypass valve to the bypass position according to a preset first trigger condition, operate the brake fluid pump until a second trigger condition, and then readjust the bypass valve to the normal operating position. The first and second trigger conditions are preferably related to changes in the temperature of the brake fluid and / or the operating state of the vehicle. The second trigger condition is preferably different from the first trigger condition. This has the advantage of improving the simple and efficient preheating of the brake fluid, especially in cold weather, through simple devices and inexpensive methods. Furthermore, this further improves the wear, durability, and operational safety of the braking system.

[0024] Particularly preferred is that the first triggering condition includes a temperature below a predetermined external temperature, a temperature below a predetermined temperature of the brake fluid, or a temperature below a predetermined temperature of a component of the vehicle; a transponder moving closer to the vehicle; unlocking the vehicle; activating the vehicle's onboard electronics; starting the vehicle's electric motor; operating the vehicle's start button to specifically initiate a preheating process; or heating the vehicle's battery using a battery preheating device. The first triggering condition preferably has a combination of multiple such conditions. This has the advantage of improving the simple and efficient preheating of the brake fluid, especially in cold weather, through simple devices and inexpensive methods. Furthermore, this further improves the wear, durability, and operational safety of the braking system.

[0025] According to a preferred embodiment of the invention, the second triggering condition includes reaching a preset upper limit temperature of the brake fluid or exceeding a predefined duration of operation of the brake fluid pump when the bypass valve is arranged in the bypass position. The predefined duration preferably depends on the initial temperature of the brake fluid before the preheating process begins, and thus the duration increases as the temperature decreases. For this purpose, a table or feature field can be provided, for example, that determines the relationship between the duration and the initial temperature. This ensures that the viscosity of the brake fluid decreases after the preheating process, thereby ensuring normal or at least improved operation of the braking device. This has the advantage of improving the simple and efficient preheating of the brake fluid, especially in cold conditions, through simple devices and inexpensive methods. Furthermore, this further improves the wear, durability, and operational safety of the braking system.

[0026] The technical problem described above is solved according to a second aspect of the invention by a motor vehicle. The motor vehicle has a drive system for driving the motor vehicle. According to the invention, the motor vehicle has a braking system according to the invention. The drive system is preferably designed as a hybrid drive system, particularly as a full hybrid or plug-in hybrid system, or as an electric drive system.

[0027] All the advantages described with respect to the braking system according to the first aspect of the invention are obtained in the motor vehicle according to the invention. Therefore, the motor vehicle according to the invention has the advantage over conventional motor vehicles in that it ensures simple and efficient preheating of the brake fluid, especially in cold weather, through simple components and inexpensive methods. By connecting a bypass line and thereby avoiding or at least significantly reducing the loading of the brake fluid on the braking device, the brake fluid can be preheated even when the vehicle is already running, without the braking device braking or locking one or more wheels. In this way, the wear, durability, and operational safety of the motor vehicle's braking system are greatly improved compared to known motor vehicles. Attached Figure Description

[0028] The braking system according to the invention and the motor vehicle according to the invention are further described below with reference to the accompanying drawings. The drawings schematically illustrate:

[0029] Figure 1 A schematic diagram of a braking system according to a preferred first embodiment of the present invention is shown;

[0030] Figure 2 A schematic diagram of a braking system according to a preferred second embodiment of the present invention is shown;

[0031] Figure 3 A schematic diagram of a braking system according to a preferred third embodiment of the present invention is shown; and

[0032] Figure 4 A side view of a preferred embodiment of a motor vehicle according to the present invention is shown.

[0033] exist Figures 1 to 4 Components with the same function and mode of operation are respectively equipped with the same reference numerals. Detailed Implementation

[0034] exist Figure 1 The diagram schematically illustrates a braking system 1 according to a preferred first embodiment of the present invention. The braking system 1 has a plurality of braking devices 3 for respectively braking a motor vehicle 2 (see [reference]). Figure 4 Wheel 4 (see) Figure 4 The braking system further includes a brake fluid reservoir 7 and a brake fluid pump 5 for providing brake fluid. The brake fluid pump has a pump inlet 8 and a pump outlet 9 leading to the brake fluid reservoir 7. The brake fluid pump 5 is designed to pump brake fluid from the brake fluid reservoir 7 to the pump outlet 9. A valve device 19 is arranged on the pump outlet 9 for selectively directing the pumped brake fluid to individual braking devices 3 via independent brake fluid lines 18. A bypass valve 10 is integrated in the valve device 19, through which brake fluid can be selectively directed to a bypass line 11 of the braking system 1 in a bypass position. The bypass valve 10 can also be placed in a normal operating position, in which the bypass line 11 toward the pump outlet 9 is closed. The braking system 1 also includes a control device 6. The control device 6 is configured to control the brake fluid pump 5, the valve device 19, and the bypass valve 10.

[0035] Figure 2 A schematic diagram of a braking system 1 according to a preferred second embodiment of the present invention is shown. The preferred second embodiment of the present invention and... Figure 1 The difference in the first embodiment of the invention shown is the addition of a throttle valve 14, which is arranged on the bypass line 11 and designed to throttle the brake fluid flow guided through the bypass line 11. As an alternative or supplement to this throttle valve 14, a pressure valve (not shown) may be provided on the bypass line 11.

[0036] exist Figure 3 The diagram schematically illustrates a braking system 1 according to a preferred third embodiment of the present invention. The preferred third embodiment of the present invention and... Figure 1 The difference in the first embodiment of the invention shown is the heating device 12, through which the bypass conduit is guided. The heating device 12 is preferably designed for use with the vehicle's battery 16 (see [link to original text]). Figure 4 ) Battery preheating device 13 for preheating.

[0037] Figure 4 A side view schematically illustrates a preferred embodiment of a motor vehicle 2 according to the invention. The motor vehicle 2 has a drive system 17, which includes electric motors 15 for driving wheels 4 of the motor vehicle 2. Braking systems 1 according to the invention (see [reference]) are arranged on each of these wheels 4. Figure 3 The braking device 3 is used to selectively brake the wheels 4. The drive system 17 has a battery 16, which has a heating device 12 designed as a battery preheating device 13 for preheating the battery at low ambient temperatures. The control device 6 is preferably designed to control components of the braking system 1 and to control the heating device 12.

[0038] List of reference numerals

[0039] 1. Braking system

[0040] 2 Motor vehicles

[0041] 3. Braking device

[0042] 4 wheels

[0043] 5. Brake fluid pump

[0044] 6. Control device

[0045] 7 Braking fluid storage

[0046] 8 Pump inlet

[0047] 9. Pump outlet

[0048] 10. Bypass valve

[0049] 11 Bypass pipe

[0050] 12 Heating device

[0051] 13 Battery preheating device

[0052] 14 Throttling valve

[0053] 15 Electric motors

[0054] 16 batteries

[0055] 17 Drive System

[0056] 18 Brake fluid lines

[0057] 19 Valve assembly

Claims

1. A braking system (1) for a motor vehicle (2), the braking system having a plurality of braking devices (3), a brake fluid pump (5), a control device (6) for controlling the brake fluid pump (5), and a brake fluid reservoir (7) for containing brake fluid, the braking devices being used to brake the wheels (4) of the motor vehicle (2) respectively, the brake fluid pump being used to generate braking pressure for operating the braking devices (3), wherein, The brake fluid pump (5) has a pump inlet (8) and a pump outlet (9), the pump inlet being fluidly coupled to the brake fluid storage device (7), and the pump outlet being fluidly coupled to the brake device (3). Its features are, The braking system (1) has a bypass line (11) operable by a bypass valve (10) for pumping brake fluid from the brake fluid pump (5) to the brake fluid reservoir (7) without passing through the braking device (3), wherein the bypass valve (10) has a bypass position and a normal operating position, wherein, The bypass valve (10) is designed to enable the transmission of brake fluid from the pump outlet (9) to the bypass line (11) in the bypass position and to prevent the transmission of brake fluid from the pump outlet (9) to the bypass line (11) in the normal operating position. The bypass valve (10) is designed to prevent the transmission of brake fluid from the pump outlet (9) to the braking device (3) in the bypass position and to enable the transmission of brake fluid from the pump outlet (9) to the braking device (3) in the normal operating position.

2. The braking system (1) according to claim 1, Its features are, The bypass pipe (11) is directed close to the heating device (12) of the vehicle (2) for heat exchange.

3. The braking system (1) according to claim 2, Its features are, The heating device (12) is designed as a battery preheating device (13) for a motor vehicle (2).

4. The braking system (1) according to claim 1, Its features are, A throttle valve (14) and / or a pressure valve are arranged on the bypass line (11).

5. The braking system (1) according to claim 1, Its features are, The control device (6) is designed to adjust the bypass valve (10) to the bypass position according to a preset first trigger condition, run the brake fluid pump (5) until the second trigger condition, and then readjust the bypass valve (10) to the normal operating position.

6. The braking system (1) according to claim 5, Its features are, The first triggering conditions include a temperature lower than a predetermined external temperature, a temperature lower than a predetermined temperature of the brake fluid, or a temperature lower than a predetermined temperature of a component of the motor vehicle (2), a transponder moving closer to the motor vehicle (2), unlocking the motor vehicle (2), turning on the on-board electronics of the motor vehicle (2), starting the motor (15) of the motor vehicle (2), operating the start button of the motor vehicle (2) to initiate a preheating process in a targeted manner, or heating the battery (16) of the motor vehicle (2) by means of a battery preheating device (13).

7. The braking system (1) according to claim 5 or 6, Its features are, The second triggering condition includes reaching a preset upper limit temperature of the brake fluid or exceeding a predefined duration of operation of the brake fluid pump (5) when the bypass valve (10) is arranged in the bypass position.

8. A motor vehicle (2) having a drive system (17) for driving the motor vehicle (2), Its features are, The motor vehicle (2) has a braking system (1) according to any one of the preceding claims.

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