Hydraulic brake unit

Abstract

The invention relates to a hydraulic brake assembly (10) for braking a motor vehicle. The hydraulic brake assembly (10) comprises a hydraulic unit (22) to which a drive motor (18) is attached, which drives at least one hydraulic pump (42) of the hydraulic unit (22). Furthermore, the hydraulic brake assembly (10) comprises at least one valve (50) for regulating the brake fluid flow and a brake fluid reservoir (30) for supplying and storing brake fluid. The hydraulic brake assembly (10) is associated with a single brake caliper (14) of the motor vehicle and is designed to be rigidly connected to the brake caliper (14) or connected via a hydraulic line (106), with the brake fluid reservoir (30) being located within the hydraulic unit (22).

Description

[0001] The present invention relates to a hydraulic brake unit for braking a motor vehicle. Furthermore, the invention relates to a braking system for a motor vehicle comprising at least two hydraulic brake units. State of the art

[0002] Hydraulic braking systems for vehicles typically include a central unit that controls the braking of all wheels simultaneously. The energy required for braking is transmitted from this central unit to the wheel brakes via a pressure-resistant fluid. These are therefore hydraulic braking systems. Rigid lines are required to transmit the fluid and its pressure. If one hydraulic line fails, the vehicle can still be braked using the other wheel brakes, thus providing redundancy. However, a failure of the sole drive motor or its control unit would result in a complete failure of the braking system. Therefore, it is standard practice to have a human backup system, allowing the driver to apply the necessary braking force. With this human backup system, driver assistance systems such as ABS, ESP, etc., are usually no longer possible.

[0003] WO 2009 / 004006 A1 discloses a hydraulic power unit for regulating brake pressure in a vehicle braking system. The hydraulic power unit comprises a housing block on which a control unit and an electric motor connected to the control unit are arranged. The electric motor drives a drive element, which in turn drives pump elements located within the housing block. Hydraulic connections are arranged on the top of the housing block to connect the wheel brakes hydraulically to the housing block. The housing block has recesses for low-pressure accumulators in which the hydraulic fluid is stored. Various valves are also incorporated into the housing block.

[0004] The object underlying the invention is to provide a hydraulic brake unit for braking a motor vehicle, which provides improved redundancy and requires reduced assembly effort.

[0005] The problem is solved by a hydraulic brake unit according to claim 1. Furthermore, a brake system with the features of claim 11 is specified. Preferred embodiments are described in the dependent claims. Disclosure of the invention

[0006] The invention provides a hydraulic brake assembly for braking a motor vehicle. The hydraulic brake assembly comprises a hydraulic unit to which a drive motor is attached, which drives at least one hydraulic pump of the hydraulic unit. The hydraulic brake assembly also includes at least one valve for regulating the brake fluid flow and a brake fluid reservoir for supplying and storing brake fluid. The hydraulic brake assembly is assigned to a single brake caliper of the motor vehicle and is designed to be rigidly connected to the brake caliper or connected via a hydraulic line, with the brake fluid reservoir being located within the hydraulic unit.

[0007] The hydraulic unit is advantageously designed in the form of a hydraulic block in which the individual components are arranged. This allows for a compact design. In contrast to a conventional hydraulic brake unit, this hydraulic brake unit only brakes one wheel of the vehicle. Thus, a separate hydraulic brake unit is provided for each braked wheel. If one hydraulic brake unit fails, the vehicle remains capable of braking, creating redundancy. This eliminates the need for a human backup system, particularly relevant for autonomous driving. Furthermore, the hydraulic brake unit can be significantly smaller than a conventional hydraulic brake unit. By integrating the brake fluid reservoir into the hydraulic unit, the space requirement can be considerably reduced. Additionally, the brake fluid reservoir is protected from external influences.This prevents damage to the brake fluid reservoir. By assigning the hydraulic brake unit to a single brake caliper, the need for complex hydraulic lines is eliminated, as the hydraulic brake unit is mounted on or near the brake caliper. The short line runs mean that no hydraulic fluid changes are required throughout the entire service life of the hydraulic brake unit, thus reducing maintenance. In particular, the fixed mounting of the hydraulic brake unit allows for complete hardware assembly at the supplier's site, simplifying installation.

[0008] In a preferred embodiment of the invention, a connector is arranged on the hydraulic unit for electrical connection. A power supply cable for the drive motor and a brake signal cable are connected via this connector. Thus, only one cable needs to be run to the hydraulic brake unit, simplifying its installation.

[0009] In a further preferred embodiment of the invention, the connector is configured such that a speed sensor for a vehicle wheel can be connected to it. This speed sensor, like the hydraulic brake unit, is located close to the wheel. By providing a connection for a speed sensor, additional wiring for the speed sensor is unnecessary. The speed signal is thus transmitted via a common line from the hydraulic brake unit to, for example, a control unit of the vehicle. This simplifies the installation of the speed sensor and the hydraulic brake unit.

[0010] Preferably, the hydraulic brake unit can be connected to a brake control unit of the vehicle for control purposes. The brake control unit is a central control unit for all brakes. This simplifies the control of the individual hydraulic brake units. In contrast to decentralized control units, only one control unit is required, thus saving on manufacturing costs.

[0011] In a further advantageous embodiment, the hydraulic brake unit has a separate brake control unit. The brake control unit is advantageously arranged on the hydraulic unit. A separate brake control unit further increases redundancy, so that if one brake control unit fails, the vehicle can still be braked using the remaining hydraulic brake units.

[0012] Advantageously, this allows the optimal pump to be selected for each vehicle based on its specific requirements. Various aspects, such as space requirements and the brake fluid volume needed for braking, can also be taken into account.

[0013] In a further advantageous embodiment, several piston pumps are provided, which are driven via eccentrics. The braking performance can be increased by using several piston pumps. This makes it possible to brake even large motor vehicles such as trucks with the hydraulic brake unit according to the invention.

[0014] In a practical design, the brake fluid reservoir is configured such that a pre-pressure or vacuum is applied to the brake fluid in the direction of the pump. With pre-pressure, the brake fluid is already pressurized at the pump. This pressure can be generated, for example, by a spring that compresses a piston towards the pump. This allows the pump to build up pressure more quickly. With vacuum, the brake fluid is drawn into the brake fluid reservoir. This allows the brake to be released more quickly after braking. In this case, a spring, for example, can compress the piston in the brake fluid reservoir in such a way that the volume in the reservoir is increased.

[0015] In another advantageous embodiment, a restrictor is arranged between the pump and a hydraulic connection to a brake caliper, and a pressure damping element is arranged parallel to the restrictor between the restrictor and the pump. A pressure damping element is a component that attenuates pressure surges in the brake fluid circuit. The pressure damping element can be designed in various ways. For example, it can be a pressure damping element in which an elastic component, such as a spring, a bellows, or a diaphragm, is arranged. The combination with the restrictor effectively reduces the pressure pulsations caused by the pump. These pressure pulsations are thus prevented from being transmitted to the brake cylinder.

[0016] Advantageously, a pressure sensor is installed between the pump and a hydraulic connection to a brake caliper to measure the brake pressure. This pressure sensor detects the brake fluid pressure at high frequencies. This provides the brake pressure, in addition to input variables such as vehicle acceleration and wheel speed, for control purposes. Since this pressure is proportional to the brake piston force, it provides a good approximation of the wheel braking torque, thus simplifying and improving the precision of brake control.

[0017] The problem underlying the invention is further solved by a braking system for a motor vehicle. The braking system comprises at least two hydraulic brake units according to the invention and at least one brake control unit, which can be connected to the hydraulic brake units, wherein the hydraulic brake units are each assigned to brake calipers of at least one axle of the motor vehicle. The brake control unit is connected to the hydraulic unit either electrically via a cable, wirelessly, or via a fiber optic cable. Although at least one axle has the hydraulic brake units, all axles can also have such hydraulic brake units.

[0018] Such a braking system exhibits a high degree of reliability, eliminating the need for a human fallback, meaning the system remains functional even if a hydraulic brake unit fails. Furthermore, this type of braking system offers all the advantages already described for hydraulic brake units.

[0019] Exemplary embodiments of the invention are shown in the drawing and explained in more detail in the following description. It shows: Fig. 1 Perspective view of a first embodiment of a hydraulic brake unit on a brake caliper, Fig. 2 Perspective view of an embodiment of a hydraulic unit according to the invention, Fig. 3. Illustration of a first embodiment of a circuit diagram of the hydraulic brake unit, Fig. 4 Perspective view of a second embodiment of a hydraulic brake unit on a brake caliper, Fig. 5. Illustration of a second embodiment of a circuit diagram of the hydraulic brake unit, Fig. 6 Exemplary embodiment of a hydraulic pump of the hydraulic brake unit, and Fig. 7 Example of a braking system for a motor vehicle.

[0020] In Fig. Figure 1 shows a perspective view of a first embodiment of a hydraulic brake assembly 10 on a brake caliper 14. The hydraulic brake assembly 10 comprises a drive motor 18, which is attached to a hydraulic unit 22 of the hydraulic brake assembly 10. The hydraulic brake assembly 10 also includes a connector 26, which is arranged on the hydraulic unit 22. The hydraulic brake assembly 10 is electrically connected to the motor vehicle via the connector 26. For example, brake signals for the hydraulic brake assembly 10 can be transmitted via the connector 26. Electrical energy for the drive motor 18 is also supplied via the connector 26. The hydraulic unit 22 is directly connected to the brake caliper 14 of a motor vehicle.

[0021] Fig. Figure 2 shows a perspective view of an embodiment of a hydraulic unit 22 according to the invention. For clarity, the drive motor 18 is omitted. A brake fluid reservoir 30 is formed in the hydraulic unit 22, in which a piston 38, biased by a spring 34, is arranged. The brake fluid reservoir 30 is designed as a bore in the hydraulic unit 22. The spring-loaded piston 38 is designed such that a vacuum is generated in the direction of a hydraulic pump 42 arranged in the hydraulic unit 22. A pressure equalization element 46 is attached to one end of the brake fluid reservoir 30, through which air can be released to or absorbed from the environment according to the movement of the piston 38.

[0022] The hydraulic pump 42, located in the hydraulic unit 22, is driven by the drive motor 18. The pump 42 draws brake fluid from the brake fluid reservoir 30. A valve 50, which regulates the brake fluid flow, is also located in the hydraulic unit 22. Furthermore, a pressure damping element 54 is incorporated in the hydraulic unit 22, which dampens pressure pulsations in the brake fluid flow.

[0023] In Fig. Figure 3 shows a diagram of a first embodiment of a circuit diagram of the hydraulic brake unit 10. This figure illustrates how all components are hydraulically connected. In this embodiment, the valve 50 is arranged parallel to the pump 42, so that after a braking operation, when the valve 50 is switched to a flow-through position, the brake fluid is drawn back into the brake fluid reservoir 30 by the vacuum. A pressure sensor 62 is arranged between the pump 42 and the brake cylinder 14a located in the brake caliper 14, allowing the operating pressure of the pump 42 to be measured.

[0024] Fig. Figure 4 shows a perspective view of a second embodiment of the hydraulic brake unit 10 on the brake caliper 14. For clarity, only the area of ​​the brake caliper 14 in which a brake cylinder 14a is arranged is shown. This embodiment differs from the embodiment in Fig. 1. This is achieved by allowing an additional speed sensor 66 to be connected to connector 26. This speed sensor 66 is a commonly used sensor for the wheel. The connection option at connector 14 reduces the wiring effort for the speed sensor 66. Therefore, only one cable harness needs to run from connector 14 to a control unit installed in the vehicle.

[0025] Fig. Figure 5 shows a representation of a second embodiment of a circuit diagram of the hydraulic brake unit 10. This embodiment differs from the one in Fig. In the embodiment shown in Figure 3, a bellows 70 is arranged in the reservoir instead of a spring 34. A check valve 74 is also arranged parallel to the valve 50, which compensates for temperature-related volume changes. A throttle 78 is also arranged between the pump 42 and the brake caliper 14, which restricts the flow rate. The pressure damping element 54 is connected between the pump 42 and the throttle 78, and is arranged parallel to the throttle 78. The pressure pulsations caused by the pump 42 can be compensated for by the pressure damping element 54 and the throttle 78.

[0026] Fig. Figure 6 shows an embodiment of a hydraulic pump 42 of the hydraulic brake unit. In this embodiment, three pumps 42 are provided instead of a single pump 42. These pumps 42 are designed as reciprocating piston pumps in this embodiment. Each pump 42 is connected to a shaft 86 of the drive motor 18 via an eccentric 82. Such an arrangement is used in particular to generate a high stroke volume. This is especially necessary in large and heavy motor vehicles such as trucks.

[0027] In Fig.Figure 7 shows an embodiment of a brake system 90 for a motor vehicle. In this embodiment, four hydraulic brake units 10 are provided. One hydraulic brake unit 10 is thus arranged at each wheel. All hydraulic brake units 10 are controlled via a common brake control unit 94 of the motor vehicle. The brake control unit 94 is connected to the connector 26 arranged on the hydraulic unit 22. In this embodiment, the hydraulic brake units 10 on the wheels of a front axle 98 of the motor vehicle are fixedly arranged on the brake caliper 14. In contrast, the hydraulic brake units 10 of the rear axle 102 are connected to the brake caliper 14 via a hydraulic line 106. The hydraulic brake units 10 of the rear axle can, for example, be mounted in a wheel arch of the rear wheels.By connecting the hydraulic brake unit 10 to the brake caliper 14 via a hydraulic line 106, the spring mass at the wheel is reduced. This increases driving comfort.

[0028] Although not shown, other arrangements of the hydraulic brake units 10 of the brake system 90 are also possible. For example, in a brake system 90, only brake units 10 may be arranged on the front axle. It is also possible that the brake units 10 of the front axle are connected to the brake caliper 14 via a hydraulic line 106. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2009 / 004006 A1

[0003]

Claims

[1] Hydraulic brake unit (10) for braking a motor vehicle, comprising a hydraulic unit (22) on which a drive motor (18) is arranged, via which at least one hydraulic pump (42) of the hydraulic unit (22) can be driven, at least one valve (50) for regulating a brake fluid flow, and a brake fluid reservoir (30) for providing and storing brake fluid, characterized by in that the hydraulic brake unit (10) is assigned to a single brake calliper (14) of the motor vehicle and is designed to be connected to the brake calliper (14) fixedly or via a hydraulic line (106), wherein the brake fluid reservoir (30) is arranged within the hydraulic unit (22). [2] Hydraulic brake unit (10) according to claim 1, characterized by that a connector (26) is arranged on the hydraulic unit (22) for electrical connection. [3] Hydraulic brake unit (10) according to claim 2, characterized bythat the connector (26) is designed such that a speed sensor (66) for a vehicle wheel can be connected to the connector (26). [4] Hydraulic brake unit (10) according to one of the preceding claims, characterized by that the hydraulic brake unit (10) can be connected to a brake control unit (94) of the motor vehicle for control. [5] Hydraulic brake unit (10) according to one of the preceding claims, characterized by that the hydraulic brake unit (10) has a separate brake control unit (94). [6] Hydraulic brake unit (10) according to one of the preceding claims, characterized by that the (42) [7] Hydraulic brake unit (10) according to claim 6, characterized by that several reciprocating piston pumps (42) are provided which are driven via eccentrics (82). [8] Hydraulic brake unit (10) according to one of the preceding claims, characterized bythat the brake fluid reservoir (30) is designed such that a pre-pressure or a negative pressure is applied to the brake fluid in the direction of the pump (42). [9] Hydraulic brake unit (10) according to one of the preceding claims, characterized by that a throttle (78) is arranged between the pump (42) and a hydraulic connection to a brake calliper (14), and a pressure damping element (54) is arranged parallel to the throttle (78) between the throttle (78) and the pump (42). [10] Hydraulic brake unit (10) according to one of the preceding claims, characterized by that a pressure sensor (66) is arranged between the pump (42) and a hydraulic connection to a brake calliper (14) to measure the brake pressure. [11] Braking system (90) for a motor vehicle comprising at least two hydraulic brake units (10) according to one of the preceding claims and at least one brake control unit (94) which can be connected to the hydraulic brake units (10), wherein the hydraulic brake units (10) are each assigned to brake calipers (14) of at least one axle (98, 102) of the motor vehicle.

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