Vehicle brake system and wheel brake device

Abstract

The present invention relates to a braking system for a vehicle, preferably an electric drive vehicle, comprising a brake (5) for at least one vehicle wheel (13), which does not require an additional brake hydraulic device, and which is filled with a viscous fluid (9) that generates friction in the brake (5) to generate a braking force, and which is arranged in a sealed container (3).

Description

[Technical Field]

[0001] The present invention relates to a braking system for a vehicle, preferably for an electrically driven vehicle, comprising a brake for at least one vehicle wheel, as well as to a wheel braking device. [Background technology]

[0002] Patent document 1 discloses a retarder for motor vehicles, particularly large trucks. A fluid brake is used as a retarder, which is arranged in the differential gear of the axle. A gear drive for rapid power transmission is arranged on the disc edge of the differential gear, which drives the rotor of the fluid brake and pumps brake fluid. To control the braking performance, an adjustable scoop tube pumps the brake to the desired diameter. The braking effect is then adjusted by the pressure of the brake fluid in the brake. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] DE-AS1215013 Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE INVENTION It is an object of the present invention to provide a brake system and wheel brake device for a vehicle that does not require an additional brake hydraulic device. [Means for solving the problem]

[0005] The invention will become apparent from the features of the independent claims. Advantageous developments and embodiments are the subject of the dependent claims. Further features, applicability and advantages of the invention will become apparent from the following description and from the description of exemplary embodiments of the invention shown in the drawings. This problem is solved by the subject matter of claim 1.

[0006] The brake system described above includes a brake for at least one vehicle wheel for generating a braking force, the brake being filled with a viscous fluid that generates friction within the brake, the viscous fluid-filled brake being arranged in a sealed container. By arranging the fluid in a completely closed container, an additional brake hydraulic device is omitted, thereby reducing the structural volume and weight of the brake system. Since the viscous fluid fills the brake, braking occurs due to fluid friction on the brake walls based on the inertia generated during fluid movement, so the brake operates without wear and does not emit particles into the environment. Therefore, replacement of the viscous fluid is not required.

[0007] Advantageously, the brake has a plurality of intermeshing intermediate walls, the viscosity of the fluid extending between the intermediate walls being selected according to the spacing between the opposing intermediate walls, which determines the fluid friction and therefore the braking torque of the brake.

[0008] In one embodiment, the brake is located near the wheel's electric drive unit and is preferably an integral component of the drive unit. This allows for the creation of a compact drive / brake unit that requires less installation space. Furthermore, positioning the brake near the drive unit reduces the wheel-side unsprung mass, improving the vehicle's driving comfort.

[0009] In one variant, a gear unit is arranged on the drive unit to generate the braking action, which is connected to an electric drive unit and to an auxiliary drive, the auxiliary drive being responsible for initiating or interrupting the braking action.

[0010] Another aspect of the present invention is a wheel brake device for a vehicle, comprising a brake filled with a viscous fluid disposed in a housing, the housing connected to a wheel shaft so as not to rotate relative to the wheel shaft, the wheel shaft being drivable by a hollow shaft connected to an electric drive unit. Such a wheel brake device does not require an additional brake hydraulic system, thereby reducing manufacturing costs. During operation, the housing, drive shaft, and output shaft rotate at the same rotational speed, resulting in zero brake torque when the brake is released, since no fluid friction occurs. Fluid friction caused by the shearing action of the viscous fluid creates a rotational speed difference between the wheel shaft and the hollow shaft, which in turn causes braking at the wheel.

[0011] It is advantageous if a gear unit is positioned in the housing with the brake, and this gear unit is connected to the auxiliary drive via an auxiliary hollow shaft, part of which extends outside the hollow shaft, to apply a retarding force, so that this braking action can be generated by simple structural measures.

[0012] In one embodiment, the gear unit is configured as a planetary gear unit, with the sun gear of the planetary gear unit connected to a hollow shaft connected by an electric drive unit, while the housing carries the ring gear of the planetary gear unit, and the planetary gear carrier is connected to an auxiliary hollow shaft operated by an auxiliary drive unit. Planetary gear units are well known and can be manufactured in large quantities in mass production. Therefore, this planetary gear unit is low-cost, reducing the manufacturing costs of the wheel brake device.

[0013] In one variation, the brake has a plurality of intermeshing intermediate walls, the viscosity of the fluid between which is selected according to the spacing between the opposing intermediate walls. The intermeshing intermediate walls increase the effective area of ​​fluid friction in a small mounting space, thereby improving the performance of the wheel braking device.

[0014] In one embodiment, the coaxially extending shafts are supported rotatably relative to one another and / or relative to the housing, thereby allowing all shafts and the housing to be optionally rotated relative to one another, thereby supporting the function of the wheel braking device in a small installation space.

[0015] Advantageously, the planetary gear unit is supported in the housing in a manner that prevents relative rotation depending on the case via a clutch connected to the auxiliary hollow shaft, which allows the electric vehicle to implement a brakeless driving mode in which the high-voltage drive of the vehicle is in regenerative mode, which occurs particularly when driving downhill.

[0016] Advantageously, the drive wheels are aerodynamically shaped, which is possible because the wheel brake devices do not need to be cooled, thus increasing the vehicle's range and improving its efficiency.

[0017] Other advantages, features and details will become apparent from the following description in which at least one embodiment is described in detail, with reference to the drawings where appropriate. The elements described and / or shown, either by themselves or in any meaningful combination, may form the subject matter of an invention, possibly independently of the claims, and in particular may additionally be the subject matter of one or more separate applications. Identical, similar and / or functionally identical parts are provided with the same reference signs. [Brief explanation of the drawings]

[0018] [Figure 1]1 is an embodiment of a braking system with a wheel braking device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] 1 shows an embodiment of a vehicle braking system in the form of a wheel brake device. The wheel brake device 1 comprises a housing 3 in which a brake 5 and a gear unit 7 are arranged. The housing 3 is completely filled with a viscous fluid 9 and is completely sealed against the surroundings so that the viscous fluid 9 cannot escape. The brake 5 consists of a number of intermeshing lamellae 11 as comb-like intermediate walls, between which the viscous fluid 9 is spread.

[0020] The brake 5 is non-rotatably connected to a wheel solid shaft 15 that drives the vehicle wheels 13. The housing 3 is rotatably supported on the wheel solid shaft 15 by a rolling bearing. A hollow shaft 19 driven by an electric drive unit 17 extends around the wheel solid shaft 15. The hollow shaft 19 is connected to a sun gear 21 of a planetary gear unit 23, the ring gear 25 of which is supported by the housing 3. A planetary gear carrier 27 of the planetary gear unit 23 is connected to an auxiliary hollow shaft 29, which encompasses the hollow shaft 19 and can be driven while being braked by an electromechanically operated auxiliary brake 31. The wheel solid shaft 15, hollow shaft 19, and auxiliary hollow shaft 29 are supported by each other and by a rolling bearing 33 relative to the housing 3, forming a coaxial system.

[0021] During vehicle operation, torque generated by the electric drive unit 17 is transmitted from the hollow shaft 19, which serves as the output shaft, to the wheel solid shaft 15, thereby driving the wheels 13. At this time, the wheel solid shaft 15 rotates at the same speed as the hollow shaft 19. The rotational speed difference is zero. When the brakes are applied by the vehicle driver's brake pedal operation or by a signal automatically generated by the brake system, the planetary gear carrier 27 is decelerated by the auxiliary brake 31. This deceleration is achieved by activating the auxiliary brake 31 in response to a brake signal. The deceleration torque is transmitted to the planetary gear carrier 27 of the planetary gear unit 23 via the auxiliary hollow shaft 29. At this time, the viscous fluid spreading between the lamellas 11 generates fluid friction on the lamellas, which slows the rotational movement of the wheel shaft 15. This generates a rotational speed difference between the wheel shaft 15 and the housing 3, generating a braking torque between the hollow shaft 19 and the wheel solid shaft 15, thereby braking the wheels 13.

[0022] A clutch 35 arranged inside the housing 3 has a first clutch disc 37 connected to the auxiliary hollow shaft 29 and a second clutch disc 39 connected to the housing 3 so as not to rotate relative to the shaft 29, and fixedly connects the planetary gear carrier 15 to the housing 3 while the vehicle driven by the electric drive unit is running. Therefore, the vehicle can continue to run without being braked.

Claims

1. A braking system for a vehicle, preferably for an electric drive vehicle, comprising a brake (5) for at least one vehicle wheel (13), The brake (5) is filled with a viscous fluid (9) that generates friction within the brake (5) to generate a braking force, and the brake (5) filled with the viscous fluid (9) is disposed in a sealed container (3).

2. 2. The brake system according to claim 1, wherein the brake (5) has a plurality of interlocking intermediate walls (11), and the viscosity of the fluid (9) spreading between the intermediate walls (11) is selected depending on the spacing between the opposing intermediate walls (11).

3. 3. A braking system according to claim 1 or 2, characterized in that the brake (9) is arranged in the vicinity of an electric drive unit (17) and is preferably an integral component of the drive unit (17).

4. 4. A braking system according to claim 1, wherein a gear unit (23) is arranged on the drive unit (17), the gear unit (23) being connected to the electric drive unit (17) and to an auxiliary drive (31) for generating a braking action.

5. A wheel brake device for a vehicle, comprising a brake (5), the brake (5) being arranged in a housing (3) and filled with a viscous fluid (9), the housing (3) being connected to a wheel shaft (15) in a non-rotatable manner, the wheel shaft (15) being drivable by a hollow shaft (19) connected to an electric drive unit (17).

6. 6. The wheel brake device according to claim 5, characterized in that a gear unit (23) is positioned in the housing (3) comprising the brake (5), and the gear unit (23) is connected to an auxiliary drive device (31) via an auxiliary hollow shaft (29) partly extending outside the hollow shaft (19) to apply a deceleration force.

7. 7. The wheel brake device according to claim 5 or 6, characterized in that the gear unit is formed as a planetary gear unit (23), the sun gear (21) of which is connected to the hollow shaft (19) connected by the electric drive unit (17), while the housing (3) carries the ring gear (25) of the planetary gear unit (23), and a planetary gear carrier (27) is connected to the auxiliary hollow shaft (29) operated by the auxiliary drive unit (31).

8. 8. Wheel brake device according to claim 5, characterized in that the brake (5) has a plurality of intermeshing intermediate walls (11) in the form of a comb, and the viscosity of the fluid (9) spreading between the intermediate walls (11) is selected depending on the spacing between the opposing intermediate walls (11).

9. 9. Wheel braking device according to at least one of claims 5 to 8, characterized in that the coaxially extending shafts (15, 19, 29) are supported rotatably relative to one another and / or relative to the housing (3).

10. 10. The wheel brake device according to claim 5, wherein the planetary gear unit (23) is supported on the housing (3) in a non-rotatable manner via a clutch (35) that is connected to the auxiliary hollow shaft (29) in a non-driven driving mode.

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