Patent Application
20240034294
The present invention relates to a braking system for an at least two-axle vehicle. The present invention also relates to a method for operating a braking system of an at least two-axle vehicle.
Braking systems for vehicles with at least two axles are described in the related art such as, for example, in German Patent Application No. DE 10 2016 208 529 A1, which include in each case four wheel brake cylinders, each wheel brake cylinder being hydraulically connected at a main brake cylinder of the respective braking system to a brake pedal situated upstream from the main brake cylinder.
The present invention provides a brake cylinder for an at least two-axle vehicle and a method for operating a braking system of an at least two-axle vehicle.
The present invention provides braking systems for at least two-axel vehicles that have a comparatively compact design and are producible at relatively low manufacturing costs. As will become clear based on the following description, the conventional hydraulic lines between the at least two axles of the respective vehicle equipped with the braking system are omitted in a braking system according to the present invention. This produces a savings of a relatively large amount of installation space on the respective vehicle. This also facilitates a mounting of the braking system according to the present invention on the respective vehicle.
As also becomes clear based on the following description, it is possible in a braking system according to the present invention to fully automatically/fully autonomously set the respective brake pressure in its front-wheel wheel-brake cylinders and in its rear-wheel wheel-brake cylinders, i.e., without a driver braking force being provided by a driver. This may also be referred to as a fully automatic/fully autonomous pressure setting, which is possible for all wheel brake cylinders of the braking system according to the present invention.
In addition, according to an example embodiment of the present invention, at least the respective brake pressure in the rear-wheel wheel-brake cylinders of the braking system according to the present invention may be set individually. This may also be described as a wheel-specific fully automatic/fully autonomous pressure setting at least in the rear-wheel wheel-brake cylinders of the braking system according to the present invention. It is noted, however, that a switching of the valves of the braking system according to the present invention at least in the rear-wheel wheel-brake cylinders for the wheel-specific, fully automatic/fully autonomous pressure setting at least in the rear-wheel wheel-brake cylinders of the braking system according to the present invention is generally necessary only for a modulation such as, for example, an ESP control or ABS control. For this reason, valve switching noises occur relatively seldom during an operation of the braking system according to the present invention. Reference is therefore also made to a good noise vibration harshness (NVH) characteristic of the braking system according to the present invention.
In one advantageous specific embodiment of the braking system of the present invention, a rear-axle control device of the rear axle unit is designed and/or programmed, while taking into account at least one braking setpoint signal, which is output by at least one brake actuator sensor of the vehicle to the rear-axle control device by an automatic speed control system of the vehicle, by a front-axle control device of the front axle unit and/or by a further stabilizing device of the braking system, to activate the at least one second motorized brake pressure buildup device, the first separating valve and/or the second separating valve, so that at least temporarily, while at least the first separating valve is directed into its closed position, brake fluid is transferable via the second rear-axle hydraulic path into the second rear-wheel wheel-brake cylinder with the aid of an operation of the at least one second motorized brake pressure buildup device, and/or while at least the second separating valve is directed into its closed state, brake fluid is transferable via the first rear-axle hydraulic path into the first rear-wheel wheel-brake cylinder with the aid of the operation of the at least one second motorized brake pressure buildup device. A wheel-specific pressure setting is thus implementable in both rear-wheel wheel-brake cylinders of the specific embodiment of the braking described herein with the aid of the operation of the at least one second motorized brake pressure buildup device activated by the rear-axle control device. Alternatively, the rear axle unit may also be operated while the first separating valve and the second separating valve are open.
According to an example embodiment of the present invention, the rear axle unit is preferably designed to be hydraulically separate from the front axle unit in such a way that the rear axle unit and the front axle unit are connected to one another at most via one signal line and/or bus line connected at the rear-axle control device and/or at the front-axle control device. Thus, the conventional hydraulic lines between a front axle and a rear axle of the vehicle equipped with the braking system described herein are omitted in the specific embodiment of the braking system described herein.
For example, the first front-axle hydraulic path and the second front-axle hydraulic path may extend through a shared front-axle brake circuit of the front axle unit and/or the first rear-axle hydraulic path and the second rear-axle hydraulic path may extend through a shared rear-axle brake circuit of the rear axle unit. Alternatively, however, the first front-axle hydraulic path may also extend through a first front-axle brake circuit of the front axle unit while the second front-axle hydraulic path extends through a second front-axle brake circuit of the front axle unit and/or the first rear-axle hydraulic path may extend through a first rear-axle brake circuit of the rear axle unit, while the second rear-axle hydraulic path extends through a second rear-axle brake circuit of the rear axle unit. Thus, a high degree of design freedom is possible in the design of the brake circuits of the braking system.
According to an example embodiment of the present invention, the front axle unit preferably also includes at least one first front-axle separating valve situated in the first front-axle hydraulic path and/or a second front-axle separating valve situated in the second front-axle hydraulic path. A wheel-specific pressure setting in this case is also possible in both front-axle wheel-brake cylinders.
As an advantageous refinement of the present invention, the front axle unit may also include a main brake cylinder, at which a brake actuator of the vehicle is connectable or is connected in such a way that at least one piston of the main brake cylinder delimiting at least one chamber of the main brake cylinder is adjustable with the aid of an actuation of the brake actuator by a driver of the vehicle, the at least one chamber of the main brake cylinder being hydraulically connected at the at least one first motorized brake pressure buildup device, at the first front-axle hydraulic path and/or at the second front-axle hydraulic path via at least one valveless or valve-equipped connecting line. Thus, with the aid of his/her driver braking force, the driver has the option of braking directly into the front-wheel wheel-brake cylinder in order in this way to also effectuate an (additional) brake pressure buildup in the front-wheel wheel-brake cylinder. The specific embodiment of the braking system described herein thus also includes a mechanical fall-back level.
According to an example embodiment of the present invention, the at least one first motorized brake pressure buildup device is preferably a plunger device and the at least one chamber of the main brake cylinder is hydraulically connected via the at least one connecting line at at least one plunger chamber of the plunger device, a respective opening of that least one connecting line at the at least one plunger chamber being designed in such a way that, if at least one adjustable plunger piston of the plunger device is present in its respective initial position, brake fluid is transferable out of the main brake cylinder through the at least one opening of the at least one connecting line into the plunger device, whereas, if the at least one adjustable plunger piston is moved out of its respective initial position, a brake fluid transfer out of the main brake cylinder through the at least one opening of the at least one connecting line into the plunger device is prevented with the aid of at least one sealing element attached at the at least one plunger piston and/or in the respective plunger chamber. Thus, during an operation of the plunger device, the main brake cylinder is automatically “decoupled” from the plunger device. Nevertheless, the specific embodiment of the braking system described herein is automatically transferred to its fall-back level in the case of a failure of the plunger device, in which the driver is able to brake into the front-wheel wheel-brake cylinder via the main brake cylinder and the plunger device with the aid of his/her driver braking force. A switching of a valve is therefore unnecessary for transferring the specific embodiment of the braking system described herein into the mechanical fall-back level.
Alternatively, according to an example embodiment of the present invention, at least one main brake cylinder decoupling valve may also be situated in the at least one connecting line. A transfer of the specific embodiment of the braking system described herein into its mechanical fall-back level is thus also possible by switching the at least one main brake cylinder decoupling valve.
The above=described advantages are also ensured when carrying out a corresponding method for operating a braking system of an at least two-axle vehicle. It is expressly noted that the method for operating a braking system of an at least two-axle vehicle may be refined in accordance with the specific embodiments of the braking system explained above.
Further features and advantages of the present invention are explained below with reference to the figures.
The braking system schematically represented in
The braking system includes a front axle unit 10 that includes at least one first motorized brake pressure buildup device 12, a first front-wheel wheel-brake cylinder 14a mountable/mounted at a first front wheel of the vehicle and a second front-wheel wheel-brake cylinder 14b mountable/mounted at a second front wheel of the vehicle. The at least one first motorized brake pressure buildup device 12 is hydraulically connected at first front-wheel wheel-brake cylinder 14a via a first front-axle hydraulic path and at second front-wheel wheel-brake cylinder 14b via a second front-axle hydraulic path. Thus, in the braking system of
The braking system also has a rear axle unit 18 designed to be hydraulically separate from front axle 10. Rear axle 18 includes at least one second motorized brake pressure buildup device 20, a first rear-wheel wheel-brake cylinder 22a mountable/mounted at a first rear wheel of the vehicle, and a second rear-wheel wheel-brake cylinder 22b mountable/mounted at a second rear wheel of the vehicle. The at least one second motorized brake pressure buildup device 20 is hydraulically connected via a first rear-axle hydraulic path at first rear-wheel wheel-brake cylinder 22a and via a second rear-axle hydraulic path at second rear-wheel wheel-brake cylinder 22b. For example, the first rear-axle hydraulic path and the second rear-axle hydraulic path in this case extend through a shared rear-axle brake circuit 24 of rear axle unit 18. In the example of
Rear axle unit 18 also includes a first separating valve 26a situated in the first rear-axle hydraulic path and/or a second separating valve 26b situated in the second rear-axle hydraulic path. In the braking system of
It is noted, however, that such a wheel-specific fully automatic/fully autonomous pressure setting in rear-wheel wheel-brake cylinders 22a and 22b is generally only necessary for a modulation such as, for example, for an ESP control or ABS control. During a “standard operation” of rear axle unit 18, the same rear-wheel brake pressure is usually set in both rear-wheel wheel-brake cylinders 22a and 22b, so that no valve switching noises are able to occur. A driver of the vehicle is thus not irritated in such a situation by valve switching noises.
The hydraulically separate design of front axle unit 10 from rear axle unit 18 is understood to mean that no hydraulic line extends between front axle unit 10 and rear axle unit 18. Since front axle unit 10 is designed to be hydraulically separate from rear axle unit 18, the hydraulic lines traditionally required between the axles equipped with wheel brake cylinders 14a, 14b, 22a and 22b are omitted in the brake system of
The at least one separating valve 26a and 26b may optionally be a switch valve or a continuously controllable valve suitable for differential pressure setting. The at least one separating valve 26a and 26b is preferably a normally open valve.
Rear axle unit 18 preferably also includes a rear-axle control device 28, which is designed and/or programmed to activate at least the at least one second motorized brake pressure buildup device 20, first separating valve 26a and/or second separating valve 26b with the aid of at least one control signal 28s while taking into account at least one brake setpoint signal 30. Rear-axle control device 28 is preferably designed to operate rear axle unit 18 at least temporarily in a mode in which brake fluid is transferable/is transferred via the second rear-axle hydraulic path into second rear-wheel wheel-brake cylinder 22b with the aid of an operation of the at least one second motorized brake pressure buildup device 20, while at least first separating valve 26a is controlled in its closed state and, if present, second separating valve 26b is controlled in an at least partially open state, so that an individual brake pressure increase takes place in second rear-wheel wheel-brake cylinder 22b. Alternatively or in addition, rear axle unit 18, with the aid of its rear-axle control device 28, may also be at least temporarily operable in a mode in which brake fluid is transferable/is transferred via the first rear-axle hydraulic path into first rear-wheel wheel-brake cylinder 22a with the aid of the operation of the at least one second motorized brake pressure buildup device 20 while at least second separating valve 26b is controlled in its closed state and, if present, first separating valve 26a is controlled in an at least partially open state, brake fluid is transferable/is transferred via the first rear-axle hydraulic path into first rear-wheel wheel-brake cylinder 22a with the aid of the operation of the at least one second brake pressure buildup device 20, which triggers an individual brake pressure increase in first rear-wheel wheel-brake cylinder 22a.
The at least one brake setpoint signal 30 may be output, for example, to rear-axle control device 28 by a brake actuator sensor 32 of the vehicle, by an automatic speed control system of the vehicle (not delineated), by an (optional) front-axle control device 34 of front axle unit 10 and/or by a further stabilizing device of the braking system (not shown). The at least one brake actuator sensor 32 may, for example, be a rod path sensor and/or a differential path sensor. The automatic speed control system may, for example, be an automatic system for driverless driving of the vehicle, an adaptive cruise control and/or an emergency braking system. The further stabilizing device of the vehicle may be understood to mean, in particular, an ESP control unit or an ABS control unit. Rear-axle control device 28 may thus interact with a plurality of different electronic components for pressure setting in rear-wheel wheel-brake cylinders 22a and 22b. As an advantageous refinement, rear-axle control unit 28 may also be designed to receive and to evaluate sensor signals of a pre-pressure sensor of rear axle unit 18 (not shown), of at least one wheel pressure sensor of rear axle unit 18 (not delineated) and/or of at least one wheel rotation sensor of the rear wheels (not graphically depicted). As a further advantageous refinement, rear-axle control device 28 may also be designed to also activate at least one generator-driven motor of the vehicle used for recuperative braking of the vehicle which, however, is not delineated in
In the specific embodiment of
Rear axle unit 18 and front axle unit 10 are connected to one another at most via at least one signal line and/or bus line 38 connected at rear-axle control device 28 and at front-axle control device 34. The connection between rear axle unit 18 and front axle unit 10 implemented with the aid of signal line and/or bus line 38 is thus space-saving, yet still enables a good interaction between rear axle unit 18 and front axle 10. The at least one signal line and/or bus line 38 may, for example, be a vehicle bus of the vehicle.
In addition, front axle unit 10 in the specific embodiment of
Brake actuator 42 may, for example, be a brake pedal 42. Moreover, the at least one chamber of main brake cylinder 40 is hydraulically connected via at last one connecting line 44 at the at least one first motorized brake pressure buildup device 12, at the first front-axle hydraulic path, and/or at the second front-axle hydraulic path. Thus, at the braking system of
The at least one connecting line 44 may optionally be a valveless or valve-equipped connecting line 44. As an advantageous refinement, at least one main brake cylinder decoupling valve 46 may also be situated in the at least one connecting line 44. Thus, by closing the at least main brake cylinder decoupling valve 46, main brake cylinder 40 may be uncoupled from the at least one motorized brake pressure buildup device 12 during an operation of the at least one first motorized braking pressure buildup device 12 in such a way that the driver braking force applied to brake actuator 42 has no influence on the at least one front-wheel brake pressure present in front-wheel wheel-brake cylinders 14a and 14b. The at least one main brake cylinder decoupling valve 46 is preferably a normally open valve. Although not represented in
In addition, at least one brake pressure buildup device decoupling valve 48 may also be used in front-axle brake circuit 16 in such a way that the at least one first motorized brake pressure buildup device 12 is decouplable/is decoupled from the at least one connecting line 44 during the mechanical fall-back mode by closing the at least one brake pressure buildup device decoupling valve 48, and thus as a “volume sink,” does not adversely affect the brake pressure increase effectuated with the aid of the driver braking force in front-wheel wheel-brake cylinders 14a and 14b. For the at least one brake pressure buildup device decoupling valve 48, a normally closed valve is preferred.
In the braking system of
In the braking system of
Moreover, the at least one second motorized brake pressure buildup device 20 in the braking system of
With regard to further features of the braking system of
Front axle unit 10 schematically shown in
With regard to further features of the braking system of
In front axle unit 10 schematically represented in
With regard to further features of the braking system of
In the case of front axle unit 10 schematically represented in
With regard to further features of the braking system of
In the case of front axle unit 10 schematically represented in
For example, the only chamber of main brake cylinder 40 in the brake system of
With regard to further features of the braking system of
In contrast to the specific embodiment of
With regard to further features of the braking system of
In front axle unit 10 reproduced in
With regard to further features of the braking system of
All of the braking systems described above require no new technology for their manufacture. Instead, it is possible to resort to already existing components/parts when manufacturing the braking systems described above.
The method described below is implementable with any braking system that includes a front axle unit including at least one first motorized brake pressure buildup device, which is hydraulically connected via a first front-axle hydraulic path at a first front-wheel wheel-brake cylinder of a first front wheel of the vehicle and via a second front-axle hydraulic path at a second front-wheel wheel-brake cylinder of a second front wheel of the vehicle, and a rear axle unit designed to be hydraulically separate from the front axle unit, including at least one second motorized brake pressure buildup device, which is hydraulically connected via a first rear-axle hydraulic path at a first rear-wheel wheel-brake cylinder of a first rear wheel of the vehicle and via a second rear-axle hydraulic path at a second rear-wheel wheel-brake cylinder of a second rear wheel of the vehicle. A feasibility is limited neither to a particular type of braking system nor to a specific vehicle type/motor vehicle type of the vehicle/motor vehicle equipped with the braking system.
As at least one of method steps S1 and S2, the at least one second motorized brake pressure buildup device, a first separating valve situated in the first rear-axle hydraulic path, and/or a second separating valve situated in the second rear-axle hydraulic path are activated taking at least one brake setpoint signal into account. The at least one brake setpoint signal is output by at least one brake activation element sensor of the vehicle, at least one automatic speed control system of the vehicle, at least one front-axle control device of the front axle unit and/or at least one further stabilizing device of the braking system. As a method step S1, the at least one second motorized brake pressure buildup device, the first separating valve and/or the second separating valve are activated in such a way that at least temporarily, while at least the first separating valve is directed into and/or held in its closed position, brake fluid is transferable via the second rear-axle hydraulic path into the second rear-wheel wheel-brake cylinder with the aid of an operation of the at least one second motorized brake pressure buildup device. Alternatively or in addition, as method step S2, the at least one second motorized brake pressure buildup device, the first separating valve and/or the second separating valve are activated in such a way that, at least temporarily, while the at least second separating valve is directed into and/or held in its closed state, brake fluid is transferred via the first rear-axle hydraulic path into the first rear-wheel wheel-brake cylinder with the of the operation of the at least one second motorized brake pressure buildup device. An implementation of the method described herein yields the advantages already enumerated above. Optionally, it is possible in a non-delineated method step to actuate the at least one second motorized braking pressure buildup device when the first separating valve is open and when the second separating valve is open.
All of the front axle units and rear axle units described above may be used to carry out the method described herein. A feasibility of the method is, however, not limited to the use of these front axle units and rear axle units.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 216 321.9 | Dec 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/084971 | 12/9/2021 | WO |
