Braking system and method for braking a vehicle with at least two axles

Abstract

The present invention relates to a braking system for at least two-axle vehicles, comprising a first axle unit (10) with a motor-type brake pressure generating device (12) that can be mounted or is mounted on a first axle of the vehicle, a first wheel brake cylinder (14a) and a second wheel brake cylinder (14b), and a second wheel brake cylinder (14c) that can be mounted or is mounted on a second axle of the vehicle and is hydraulically separated from the first axle unit (10). The vehicle has at least two axle units, the first axle unit (10) including a first outlet valve (18a) associated with the first wheel brake cylinder (14a) and a second outlet valve (18b) associated with the second wheel brake cylinder (14b), and capable of discharging brake fluid from the first wheel brake cylinder (14a) via the first outlet valve (18a) and from the second wheel brake cylinder (14b) via the second outlet valve (18b) into a connected brake fluid reservoir (16). The invention likewise relates to a method for braking a vehicle with at least two axles.

Description

[Technical Field]

[0001] The present invention relates to a braking system for a vehicle with at least two axles. Likewise, the present invention relates to a method for braking a vehicle with at least two axles. [Background technology]

[0002] From the prior art, for example from patent document 1, a braking system for a two-axle vehicle is known which has exactly two brake circuits each with two wheel brake cylinders, each of which is hydraulically connected to the master brake cylinder of the respective brake system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] German Patent Application Publication No. 102016208529 Summary of the Invention

[0004] The invention relates to a braking system for a vehicle with at least two axles according to the features of claim 1 and to a method for braking a vehicle with at least two axles according to the features of claim 10.

[0005] The present invention provides a brake system for at least two axles of a vehicle that has a relatively compact structure and can be produced at relatively low manufacturing costs. As will become clear with reference to the following description, the brake system according to the present invention eliminates the need for conventional hydraulic piping between the at least two axles of the vehicle in which the brake system is respectively installed. This results in a relatively large reduction in design space in the respective vehicle. In addition, the assembly of the brake system according to the present invention into the respective vehicle is also correspondingly simplified.

[0006] One particular advantage of the brake system provided by the present invention is that at least the first axle unit is configured as an open system, in which case the first axle unit is flushed by brake fluid flow in the same direction to generate and release pressure in its first and second wheel brake cylinders. The flow of brake fluid drawn in by the motor-driven brake pressure generator from a connected brake fluid reservoir and then released from the first and / or second wheel brake cylinders to the brake fluid reservoir causes a "thorough" flushing of the first axle unit, preventing air accumulation in the first axle unit. Therefore, the brake system of the present invention does not require concern about malfunctions due to air accumulation in the first axle unit.

[0007] As will become more apparent with reference to the following description, the braking system according to the invention allows the respective brake pressures in the wheel brake cylinders of its first axle unit to be adjusted fully automatically / autonomously, i.e. without the driver providing any driver braking force, which may also be referred to as fully automatic / autonomous pressure regulation.

[0008] The first axle unit is preferably a "front axle unit." Thus, in the braking system according to the present invention, a first brake pressure in a first wheel brake cylinder, which serves as a front axle wheel brake cylinder, and a second brake pressure in a second wheel brake cylinder, which also serves as a front axle wheel brake cylinder, can be adjusted fully automatically / autonomously, i.e., without the driver of the respective vehicle providing a driver brake force. Alternatively, however, the first axle unit may be a "rear axle unit," which has a first wheel brake cylinder, which serves as a rear axle wheel brake cylinder, and a second wheel brake cylinder, which serves as a rear axle wheel brake cylinder. In this case, too, the first brake pressure in the first wheel brake cylinder and the second brake pressure in the second wheel brake cylinder can be adjusted fully automatically / autonomously.

[0009] For example, the brake circuit of the first axle unit may include at least a first wheel brake cylinder, a first outlet valve, a second wheel brake cylinder, and a second outlet valve, and the motor-type brake pressure generator is integrated into the brake circuit or hydraulically connected to the brake circuit, thus enabling the first axle unit to be configured as a single-circuit first axle unit.

[0010] Alternatively, the first brake circuit of the first axle unit can include at least a first wheel brake cylinder and a first discharge valve, and the second brake circuit of the first axle unit can include at least a second wheel brake cylinder and a second discharge valve, with the first brake circuit hydraulically connected to a first chamber of a motorized brake pressure generator configured as a piston-cylinder device, and the second brake circuit hydraulically connected to a second chamber of the piston-cylinder device. The described dual-circuit configuration of the first axle unit improves the robustness of the first axle unit against leaks in one of its brake circuits. Even if a leak occurs in one of the first axle unit's brake circuits during autonomous / automated driving of a vehicle equipped therewith, the vehicle equipped therewith can at least be brought to a safe stop.

[0011] The first axle unit is preferably hydraulically isolated from the second axle unit such that the first and second axle units are connected to each other at most via at least one signal line and / or bus line. Accordingly, embodiments of the brake systems described herein eliminate the need for conventional hydraulic piping between the first and second axles of a vehicle equipped with the brake systems described herein.

[0012] In a preferred development, the first axle unit can additionally include a master brake cylinder, to which a brake operating element of the vehicle can be connected or which is connected such that at least one piston of the master brake cylinder, which separates at least one chamber of the master brake cylinder, can be adjusted in position by the driver of the vehicle operating the brake operating element, and brake fluid can be transferred from the at least one chamber of the master brake cylinder to at least one of the first and / or second wheel brake cylinders via at least one valveless or valve-equipped connecting pipe. In this way, the driver has the possibility to directly apply brake force to the wheel brake cylinders of the first axle unit and thus further trigger brake pressure generation in the wheel brake cylinders of the first axle unit. Accordingly, the embodiments of the brake system described herein also have a mechanical fallback level.

[0013] Preferably, the first discharge valve is hydraulically connected to the second discharge valve via a connecting section, and a single valveless or valve-equipped connecting pipe communicates with the connecting section, and a first check valve arranged in parallel with the first discharge valve is oriented such that the first check valve prevents brake fluid from flowing from the first wheel brake cylinder to the connecting section through the connecting pipe, and / or a second check valve arranged in parallel with the second discharge valve is oriented such that the second check valve prevents brake fluid from flowing from the second wheel brake cylinder to the connecting section through the connecting pipe. In this way, even when the first and / or second discharge valves are closed, brake fluid can be transferred from the master brake cylinder via the first and / or second check valves to at least one wheel brake cylinder located downstream of the first axle unit at a mechanical fallback level.

[0014] In another preferred embodiment of the brake system, the motor-operated brake pressure generator is a piston-cylinder device having at least one chamber, and the master brake cylinder is hydraulically connected to the piston-cylinder device via at least one valveless or valve-equipped connecting pipe, the at least one connecting pipe having a respective connecting pipe connection to the at least one chamber of the piston-cylinder device, the at least one connecting pipe being capable of transferring brake fluid from the master brake cylinder via the at least one connecting pipe and its respective connecting pipe connection to the at least one chamber of the piston-cylinder device when the at least one adjustable piston of the piston-cylinder device is in its respective initial position, whereas the transfer of brake fluid from the master brake cylinder via the at least one connecting pipe and its respective connecting pipe connection to the at least one chamber of the piston-cylinder device is prevented by at least one sealing element mounted on a surface of the at least one adjustable piston of the piston-cylinder device and / or in the at least one chamber of the piston-cylinder device when the at least one adjustable piston is displaced from its respective initial position. In this way, the master brake cylinder is automatically "isolated" from the piston-cylinder device during operation of the piston-cylinder device. Nevertheless, the embodiments described herein automatically transition to a fallback level in the event of a piston-cylinder device failure, allowing the driver to apply driver braking force to the wheel brake cylinders of the first axle unit via the master brake cylinder and piston-cylinder device. In this way, no valve switching is required to transition the embodiments of the braking system described herein to a mechanical fallback level.

[0015] In a further preferred development, the first wheel brake cylinder can be hydraulically connected to a motorized brake pressure generator via a first isolation valve and / or the second wheel brake cylinder via a second isolation valve. This allows wheel-individual pressure regulation in both wheel brake cylinders of the first axle unit. This can also be translated as wheel-individual, fully automatic / fully autonomous pressure regulation in the wheel brake cylinders of the first axle unit of the brake system according to the present invention. However, it should be noted that switching of the first and / or second isolation valves for wheel-individual, fully automatic / fully autonomous pressure regulation in the wheel brake cylinders is usually only required for modulation, for example, of ESP control or ABS control. Therefore, relatively little valve switching noise occurs during operation of the brake system according to the present invention. Therefore, the brake system according to the present invention also has good NVH characteristics (Noise, Vibration, Harshness Characteristics).

[0016] In another preferred development, the third check valve arranged in parallel with the first isolation valve may be oriented such that the third check valve prevents brake fluid transfer from the first wheel brake cylinder to the motorized brake pressure generator. Alternatively or additionally, the fourth check valve arranged in parallel with the second isolation valve may also be oriented such that the fourth check valve prevents brake fluid transfer from the second wheel brake cylinder to the motorized brake pressure generator. In the brake system embodiments described herein, when the first / second isolation valve is "stuck" in its closed state, the first / second motorized brake pressure generator can still transfer brake fluid to the first / second wheel brake cylinder via the third / fourth check valve. Thus, additionally equipping a brake system with a third and / or fourth check valve increases the safety level of the respective brake system.

[0017] The advantages described above are also ensured when a corresponding method for braking a vehicle with at least two axles is implemented, which method for braking a vehicle with at least two axles can be explicitly pointed out as being capable of being developed in accordance with the respective embodiments of the braking system described above.

[0018] Further features and advantages of the present invention will be described below with reference to the drawings, in which: [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 2] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 3] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 4] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 5]1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 6] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 7] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 8] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 9] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 10] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 11] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 12] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 13] 1 is a schematic partial view illustrating an embodiment of a brake system. [Figure 14] 1 is a flow chart illustrating one embodiment of a method for braking a vehicle with at least two axles. DETAILED DESCRIPTION OF THE INVENTION

[0020] FIG. 1 shows a schematic partial view of a first embodiment of a braking system.

[0021] The brake system shown diagrammatically in FIG. 1 can be / is installed on a vehicle / automobile with at least two axles, but the applicability of this brake system is not limited to a particular vehicle make / automobile type of a two-axle vehicle / automobile.

[0022] The braking system of Figure 1 includes a first axle unit 10 that can be mounted on a first axle of a vehicle. The braking system also includes at least one second axle unit that can be mounted on a second axle of the vehicle and is hydraulically isolated from the first axle unit 10, although this is not shown explicitly in Figure 1. The second axle unit is configured such that operation of the second axle unit can brake a first wheel of the second axle and a second wheel of the second axle. If the vehicle equipped with the braking system has two or more axles, the braking system may further include at least one third axle unit that is hydraulically separated from the first axle unit 10 and the second axle unit, and the at least one third axle unit may also be / be assembled to at least one third axle of the vehicle, and is configured such that a first wheel of the at least one third axle and a second wheel of the at least one third axle can / are braked by operation of the at least one third axle unit.

[0023] The hydraulically decoupled first axle unit 10 from the second axle unit means that no hydraulic lines extend between the first axle unit 10 and the second axle unit. In particular, the first axle unit 10 may be hydraulically decoupled from the second axle unit such that the first axle unit 10 and the second axle unit are connected to each other at most via at least one signal line and / or bus line. Because the first axle unit 10 is hydraulically decoupled from the second axle unit, the brake system of FIG. 1 does not require hydraulic lines that would conventionally be required between each axle equipped with a wheel brake cylinder. This results in a very compact and space-saving design. In particular, the modular design of the brake system allows for relatively low manufacturing costs. Furthermore, the first axle unit 10 and the second axle unit can be installed as two separate units on a two-axle vehicle equipped with them. This also simplifies the assembly of the brake system described here. Accordingly, the configuration of the at least one third axle unit hydraulically separated from the first axle unit 10 and the second axle unit is also understood to mean that no hydraulic lines extend between the at least one third axle unit and the first axle unit 10 or the second axle unit.

[0024] Preferably, the first axle unit 10 can be / is mounted to the front axle of the vehicle as a "front axle unit," while the second axle unit and possibly at least one third axle unit can be / is mounted to the rear axle of the vehicle as a "rear axle unit" and / or to at least one axle located between the front and rear axles of the vehicle as an "intermediate axle unit." In this case, the first axle unit 10 serves to brake the front wheels of the vehicle, while the second axle unit and possibly at least one third axle unit can brake the rear and / or intermediate wheels of the vehicle. However, alternatively, the first axle unit 10 can be / is mounted to the rear axle of the vehicle as a "rear axle unit" or to at least one axle located between the front and rear axles of the vehicle as an "intermediate axle unit."

[0025] The first axle unit 10 has a motor-driven brake pressure generator 12, a first wheel brake cylinder 14a, and a second wheel brake cylinder 14b. The motor-driven brake pressure generator 12 is configured to transfer brake fluid from a connected brake fluid reservoir 16 to the first wheel brake cylinder 14a and the second wheel brake cylinder 14b by operation of the motor-driven brake pressure generator 12. In this way, a first brake pressure in the first wheel brake cylinder 14a and a second brake pressure in the second wheel brake cylinder 14b can be increased, thereby braking a first wheel of the first axle associated with the first wheel brake cylinder 14a and a second wheel of the first axle associated with the second wheel brake cylinder 14b. The first axle unit 10 further includes a first outlet valve 18a associated with the first wheel brake cylinder 14a and a second outlet valve 18b associated with the second wheel brake cylinder 14b. This ensures that the first axle unit 10 can discharge brake fluid from the first wheel brake cylinder 14a via the first outlet valve 18a and from the second wheel brake cylinder 14b via the second outlet valve 18b to the connected brake fluid reservoir 16. The first and second outlet valves 18a and 18b are preferably normally closed valves.

[0026] In the first axle unit 10 of the brake system of FIG. 1 , the brake fluid flow drawn from the connected brake fluid reservoir 16 by the motor-driven brake pressure generator 12 and then discharged from the first wheel brake cylinder 14 a and / or the second wheel brake cylinder 14 b to the brake fluid reservoir 16 always flows in the same direction. Due to pressure buildup and pressure release in the first wheel brake cylinder 14 a and the second wheel brake cylinder 14 b, the first axle unit 10 is always flushed by the brake fluid flow that always flows in the same direction. Therefore, the first axle unit 10 of the brake system of FIG. 1 is an open system. Furthermore, the brake fluid flow that flows in the same direction in the first axle unit 10 causes a "thorough" flushing of the first axle unit 10, so that air accumulation in the first axle unit 10 is not possible. Consequently, malfunctions caused by air accumulation in the first axle unit 10 are not a concern during operation of the brake system of FIG. 1 .

[0027] The braking system described herein has the advantage that, at least in its first axle unit 10, frequent and "thorough" flushing of the first axle unit 10 by brake fluid flows directed in the same direction reliably prevents air buildup, and therefore, the motor-driven brake pressure generator 12 can be used to trigger fully autonomous / fully automatic brake pressure generation in the wheel brake cylinders 14a and 14b of the first axle unit 10. In this way, not only the first brake pressure in the first wheel brake cylinder 16a but also the second brake pressure in the second wheel brake cylinder 16b can be generated / increased fully autonomously / fully autonomously, i.e., without the driver of the respective vehicle providing a driver brake force. The first axle unit 10 is therefore particularly well suited for autonomous / fully automatic braking of the vehicle equipped therewith, particularly during fully autonomous / fully automatic driving of the respective vehicle.

[0028] Furthermore, many of the "same" parts, i.e., the same types of parts, can be utilized for the first axle unit 10. Thus, the axle unit 10 is relatively low cost and can be manufactured using brake system components that are already in use.

[0029] The motor-based brake pressure generator 12 may be, for example, at least one pump, which allows the first axle unit 10 to be configured at relatively low cost. However, the configuration of the motor-based brake pressure generator 12 as at least one pump of the first axle unit 10, as specifically shown in Figure 1, should be interpreted as an example only.

[0030] In a preferred development, in the first axle unit 10, the first wheel brake cylinder 14a is hydraulically connected to the motor-based brake pressure generator 12 via the first isolation valve 20a. That is, the first wheel brake cylinder 14a can be / is isolated from the motor-based brake pressure generator 12 by closing the first isolation valve 20a, while brake fluid can / is still be transferred to the second wheel brake cylinder 14b by the motor-based brake pressure generator 12. Alternatively or additionally, the second wheel brake cylinder 14b can also be hydraulically connected to the motor-based brake pressure generator 12 via the second isolation valve 20b. If necessary, the second wheel brake cylinder 14b can / is also be isolated from the motor-based brake pressure generator 12 by closing the second isolation valve 20b, while brake fluid can / is still be transferred to the first wheel brake cylinder 14a by operating the motor-based brake pressure generator 12. In this way, by equipping the first axle unit 10 with the first isolation valve 20a and / or the second isolation valve 20b, wheel-individual pressure regulation can be carried out in both wheel brake cylinders 14a and 14b of the first axle unit 10 of the brake system. Fully automatic / fully autonomous wheel-individual pressure regulation in the wheel brake cylinders 14a and 14b is conceivable, for example, for ESP control or ABS control.

[0031] Furthermore, if a leak occurs in one of the wheel brake cylinders 14a and 14b of the first axle unit 10, the preceding isolation valve 20a or 20b can be closed to isolate the respective wheel brake cylinder 14a or 14b from the motor-driven brake pressure generator 12, while still allowing fully automatic / fully autonomous pressure regulation by the motor-driven brake pressure generator 12 in the other of the wheel brake cylinders 14a and 14b. Thus, in the brake system of FIG. 1, a high degree of redundancy in the first axle unit 10 is achieved with only minor modifications. The at least one isolation valve 20a or 20b of the first axle unit 10 may optionally be a selector valve or a permanently adjustable valve suitable for differential pressure regulation. Preferably, the at least one isolation valve 20a or 20b is a normally open valve.

[0032] Optionally, the first axle unit 10 may also have a first isolation valve / check valve 22a arranged in parallel with the first isolation valve 20a, which is oriented such that the first isolation valve / check valve 22a prevents brake fluid transfer from the first wheel brake cylinder 14a toward the motor-type brake pressure generator 12. In this way, when the first isolation valve 20a is "stuck" in its closed state, the motor-type brake pressure generator 12 can transfer brake fluid to the first wheel brake cylinder 14a via the first isolation valve / check valve 22a. Similarly, a second isolation valve / check valve 22b arranged in parallel with the second isolation valve 20b may be preferred, which is oriented such that the second isolation valve / check valve 22b prevents brake fluid transfer from the second wheel brake cylinder 14b toward the motor-type brake pressure generator 12. In this case, even when the second isolation valve 20b is "stuck" in its closed state, the motor-operated brake pressure generator 12 can still transfer brake fluid to the second wheel brake cylinder 14b via the second isolation valve-check valve 22b. Thus, additionally equipping the brake system / its first axle unit 10 with at least one isolation valve-check valve 22a and 22b increases the safety level of the respective brake system.

[0033] In another preferred development, the first axle unit 10 of FIG. 1 additionally has a master brake cylinder 24 to which a brake operating member 26 of the vehicle can be connected, so that at least one piston of the master brake cylinder 24, which separates at least one chamber of the master brake cylinder 24, can be adjusted by operating the brake operating member 26 by the vehicle driver. The brake operating member 26 can be, for example, a brake pedal. By operating the brake operating member 26 by the driver, brake fluid can be transferred from at least one chamber of the master brake cylinder 24 to the first wheel brake cylinder 14 a and / or the second wheel brake cylinder 14 b at least via at least one valveless or valve-equipped connecting pipe 28. 1 is provided with a mechanical fallback level, which, in particular in the event of a failure of the motor-driven brake pressure generator 12, allows the driver to still initiate brake pressure generation in the wheel brake cylinders 14a, 14b of the first axle unit 10 by means of his own driver braking force applied to the brake operating member 26. In this way, the driver can still reliably bring the vehicle to a standstill by means of the brake pressure buildup generated in the wheel brake cylinders 14a, 14b of the first axle unit 10, even in the event of a failure of the vehicle's vehicle electrical system.

[0034] At least one master brake cylinder shut-off valve 30 may be inserted into at least one connecting line 28. In this way, when the motor-driven brake pressure generator 12 is in operation, the master brake cylinder 24 may be decoupled from the motor-driven brake pressure generator 12 by closing the at least one master brake cylinder shut-off valve 30, so that the driver's braking force applied to the brake operating member 26 does not affect the brake pressure generated in each wheel brake cylinder 14a, 14b. The at least one master brake cylinder shut-off valve 30 may optionally be a selector valve or a permanently adjustable valve suitable for differential pressure regulation. Preferably, the at least one master brake cylinder shut-off valve 30 is a normally open valve. Although not shown in FIG. 1 , a simulator may also be connected to the master brake cylinder 24, so that when the at least one master brake cylinder shut-off valve 30 is closed, the driver operating the brake operating member 26 experiences a standard brake operation / pedal feel.

[0035] 1 , by way of example only, a single connecting pipe 28 equipped with a single master brake cylinder shut-off valve 30 has at its end facing away from the master brake cylinder 24 a connection 31 to a pipe section branching off from the motor-driven brake pressure generator 12 to the wheel brake cylinders 14 a, 14 b of the first axle unit 10 or to at least one isolation valve 20 a, 20 b upstream of the wheel brake cylinders 14 a, 14 b of the first axle unit 10. A further shut-off valve 32 may preferably be arranged between the connection 31 of the single connecting pipe 28 to the pipe section and the motor-driven brake pressure generator 12, so that closing the shut-off valve 32 prevents brake fluid from being transferred from the connecting pipe 28 to the motor-driven brake pressure generator 12. In this way, closing the shut-off valve 32 ensures that the motor-based brake pressure generator 12 acts as a "volume sink" during the mechanical fallback mode and does not impair the brake pressure build-up caused by the driver braking force in the wheel brake cylinders 14a, 14b of the first axle unit 10. The shut-off valve 32 is preferably a normally closed valve.

[0036] FIG. 2 shows a schematic partial view of a second embodiment of a braking system.

[0037] In the brake system of FIG. 2, the first discharge valve 18a is hydraulically connected to the second discharge valve 18b via a connection section 34. The connection section 34 is preferably hydraulically connected to the common brake fluid reservoir 16. In contrast to the above-described embodiment, in the first axle unit 10 of FIG. 2, a single valveless or valve-equipped connecting pipe 28 communicates with the connection section 34. To enable the driver operating the brake operating member 26 to apply brake intervention to the first wheel brake cylinder 14a and / or the second wheel brake cylinder 14b of the first axle unit 10 in the event of a mechanical fallback level of the brake system, the first axle unit 10 of FIG. 2 includes a first check valve 36a arranged in parallel with the first discharge valve 18a and / or a second check valve 36b arranged in parallel with the second discharge valve 18b. The first check valve 36a is oriented in such a direction that it prevents brake fluid from being transferred from the first wheel brake cylinder 14a towards the communication 31 of the connecting pipe 28 to the connection section 34. Similarly, the second check valve 36b is preferably oriented in such a way that it prevents brake fluid from being transferred from the second wheel brake cylinder 14b towards the communication 31 of the connecting pipe 28 to the connection section 34. In this way, the driver can still apply brake force to at least one of the wheel brake cylinders 14a and 14b of the first axle unit 10 via the first check valve 36a and / or the second check valve 36b, even during the mechanical fallback level.

[0038] In order to prevent the brake pressure buildup caused by the driver in the at least one wheel brake cylinder 14a, 14b of the first axle unit 10 from being impaired by the brake fluid reservoir 16 acting as a "volume sink", a reservoir shut-off valve 38 may further be arranged between the connection area 34 and the brake fluid reservoir 16. The reservoir shut-off valve 38 is preferably a normally closed valve. Optionally, a throttle 40 may further be inserted in the connecting pipe 28.

[0039] For other features, characteristics and advantages of the braking system of FIG. 2, please refer to the embodiment of FIG. 1 described above.

[0040] FIG. 3 shows a schematic partial view of a third embodiment of a braking system.

[0041] Unlike the embodiments described above, the first axle unit 10 of Fig. 3 has a piston-cylinder arrangement 12 with at least one chamber as the motor-type brake pressure generating device 12. The piston-cylinder arrangement 12 of Fig. 3 preferably has a first chamber and a second chamber, with the first wheel brake cylinder 14a connected to the first chamber and the second wheel brake cylinder 14b connected to the second chamber.

[0042] 3, the first axle unit 10 is also distinguished from the embodiment of FIG. 1 in that the single connecting pipe 28 branches into two sections, a first section of the branched connecting pipe 28 communicating with a section of pipe extending between the first chamber of the piston-cylinder arrangement 12 and the first isolation valve 20a, and a second section of the branched connecting pipe 28 communicating with another section of pipe extending between the second chamber of the piston-cylinder arrangement 12 and the second isolation valve 20b. Furthermore, the first master brake cylinder shut-off valve 30a is located in the first section of the branched connecting pipe 28, whereas the second master brake cylinder shut-off valve 30b is located in the second section of the branched connecting pipe 28.

[0043] For other features, characteristics and advantages of the braking system of FIG. 3, please refer to the embodiment of FIG. 1 described above.

[0044] FIG. 4 shows a schematic partial view of a fourth embodiment of a braking system.

[0045] Unlike the embodiment of Figure 2, the first axle unit 10 of the braking system of Figure 4 has, as a motor-type brake pressure generating device 12, the two-chamber piston-cylinder arrangement 12 already described above, with a separate chamber of the piston-cylinder arrangement 12 associated with each wheel brake cylinder 14a and 14b of the first axle unit 10.

[0046] Therefore, with regard to other features and characteristics of the braking system of FIG. 4 and its advantages, reference should be made to the embodiment of FIGS. 1 to 3 described above.

[0047] FIG. 5 shows a schematic partial view of a fifth embodiment of a braking system.

[0048] In the brake system of FIG. 5, the master brake cylinder 24 is a tandem master brake cylinder 24. A first chamber of the master brake cylinder 24 is connected to a piping section extending between the first wheel brake cylinder 14a and the first isolation valve 20a by a first connecting pipe 28a having a first master brake cylinder shut-off valve 30a. Similarly, a second chamber of the master brake cylinder 24 is connected to another piping section extending between the second wheel brake cylinder 14b and the second isolation valve 20b by a second connecting pipe 28b having a second master brake cylinder shut-off valve 30b. The isolation valves 20a and 20b, and possibly also the isolation valve-check valves 22a and 22b, prevent undesired transfer of brake fluid from the master brake cylinder 24 to the chamber of the piston-cylinder arrangement 12, in this case at a mechanical fallback level. In this way, the brake fluid displaced from the master brake cylinder 24 by the driver braking force can be (almost) completely utilized for building up brake pressure in the wheel brake cylinders 14a and 14b of the first axle unit 10.

[0049] For other features and advantages of the braking system of FIG. 5, please refer to the embodiment of FIGS. 1 to 4 described above.

[0050] FIG. 6 shows a schematic partial view of a sixth embodiment of a braking system.

[0051] 6, the master brake cylinder 24 is also a tandem master brake cylinder 24. However, the first communication portion 31a of the first connecting pipe 28a facing away from the master brake cylinder is formed in a pipe section extending between the first isolation valve 20a and the first chamber of the piston-cylinder arrangement 12, while the second communication portion 31b of the second connecting pipe 28b is located in another pipe section extending between the second isolation valve 20b and the second chamber of the piston-cylinder arrangement 12. Nevertheless, to prevent undesired transfer of brake fluid from the master brake cylinder 24 to the respective chambers of the piston-cylinder device 12 when the mechanical fallback level is low, the first axle unit 10 further includes a first shutoff valve 32a arranged between the first communication portion 31a of the first connecting pipe 28a and the first chamber of the piston-cylinder device 12, and a second shutoff valve 32b located between the second communication portion 31b of the second connecting pipe 28b and the second chamber of the piston-cylinder device 12. The shutoff valves 32a and 32b are preferably each a normally closed valve.

[0052] For other features and advantages of the braking system of FIG. 6, please refer to the embodiment of FIGS. 1 to 5 described above.

[0053] FIG. 7 shows a schematic partial view of a seventh embodiment of a braking system.

[0054] As can be seen in FIG. 7, the master brake cylinder 24 may be hydraulically connected to the piston-cylinder arrangement 12 via at least one connecting pipe 28 which is valveless or equipped with a valve, whereby the at least one connecting pipe 28 has one connecting pipe opening 42 respectively to at least one chamber of the piston-cylinder arrangement 12 facing away from the master brake cylinder 24. Furthermore, the at least one connecting pipe connection 42 is preferably configured such that brake fluid can be / is transferred from the master brake cylinder 24 to the at least one chamber of the piston-cylinder device 12 via the at least one connecting pipe 28 and its respective connecting pipe connection 42 when the at least one adjustable piston of the piston-cylinder device 12 is in its respective initial position, whereas transfer of brake fluid from the master brake cylinder 24 to the at least one chamber of the piston-cylinder device 12 via the at least one connecting pipe 28 and its respective connecting pipe connection 42 is prevented by at least one sealing element 44 a, 44 b, 44 c attached to a surface of the at least one adjustable piston of the piston-cylinder device 12 and / or attached in the at least one chamber of the piston-cylinder device 12 when the at least one adjustable piston is displaced from its respective initial position. Therefore, the preferred configuration of the at least one connecting pipe connection 42 described herein can also be translated as a configuration of the at least one connecting pipe connection 42 as a “compensating hole.”

[0055] Thus, the at least one preferred connecting piping connection 42 and the at least one sealing member 44a, 44b, and 44c ensure that the master brake cylinder 24 is automatically decoupled from the piston-cylinder device 12 during operation of the piston-cylinder device 12 in a functional state, so that the driver's braking force applied to the brake operating member 26 does not affect the brake pressure generated in the wheel brake cylinders 14a and 14b. In the event of a failure of the piston-cylinder device 12 and / or the vehicle's electrical system, the at least one position-adjustable piston of the piston-cylinder device 12 is normally in its initial position, thereby automatically shifting the brake system to a mechanical fallback level that still reliably generates a brake pressure increase in the wheel brake cylinders 14a and 14b sufficient for the driver to brake the vehicle with the driver's braking force. Therefore, it is not necessary for the brake system of FIG. 7 to be equipped with a master brake cylinder shut-off valve 32, 32a, or 32b.

[0056] In the first axle unit 10 of FIG. 7, the single chamber of the master brake cylinder 24 is connected to the single chamber of the piston-cylinder device 12 via the single connecting pipe 28. Illustratively, the single piston of the piston-cylinder device 12 carries three seal members 44a, 44b, and 44c attached thereto. When the piston of the piston-cylinder device 12 is in its initial position, the first seal member 44a, which is located closest to the connecting pipe communication 42, blocks pressure from the direction of the connecting pipe communication 42 and is conductive to pressure from the direction of the motor (in the opposite direction). The second seal member 44b, adjacent to the first seal member 44a, is conductive to pressure from the direction of the first seal member 44a and blocks pressure from the direction of the motor (in the opposite direction). In addition, the third seal member 44c, which is located closest to the motor of the piston-cylinder device 12, is conductive to pressure from the direction of the first seal member 44a and the second seal member 44b, and is insulated from pressure from the direction of the motor (in the opposite direction).

[0057] For other features and advantages of the braking system of FIG. 7, please refer to the embodiment of FIGS. 1 to 6 described above.

[0058] FIG. 8 shows a schematic partial view of an eighth embodiment of the brake system.

[0059] Unlike the embodiment of FIG. 7, in the first axle unit 10 of FIG. 8, the master brake cylinder shutoff valve 30 is inserted into a single connecting pipe 28. In this manner, configuring at least one connecting pipe connection 42 as a "compensating hole" and utilizing a specific seal member type can be omitted in the first axle unit 10 of FIG. 8.

[0060] For other features and advantages of the braking system of FIG. 8, please refer to the embodiment of FIGS. 1 to 7 described above.

[0061] FIG. 9 shows a schematic partial view of a ninth embodiment of a brake system.

[0062] 9 differs from the embodiment of FIG. 7 in that a first axle unit 10 uses a piston-cylinder arrangement 12 having two chambers, with a separate chamber of the piston-cylinder arrangement 12 associated with each wheel brake cylinder 14a, 14b of the first axle unit 10, and the single connecting pipe 28 branches into two sections. The first section of the branching connecting pipe 28 has a first connecting pipe connection 42a to the first chamber of the piston-cylinder arrangement 12, while the second section of the branching connecting pipe 28 has a second connecting pipe connection 42b to the second chamber of the piston-cylinder arrangement 12. Due to the configuration of each connecting-pipe connection 42a, 42b as a "compensating hole", it is ensured that brake fluid can be transferred from the master brake cylinder 24 to the respective chamber of the piston-cylinder arrangement 12 when the adjacent piston of the piston-cylinder arrangement 12 is in its respective initial position, whereas when the adjacent piston is displaced from its respective initial position, the respective connecting-pipe connection 42a or 42b is sealed by at least one sealing element 44a, 44b and 44c. For this purpose, each piston of the piston-cylinder arrangement 12 is respectively equipped with the sealing elements 44a, 44b and 44c already described above.

[0063] For other features and advantages of the braking system of FIG. 9, please refer to the embodiment of FIGS. 1 to 7 described above.

[0064] FIG. 10 shows a schematic partial view of a tenth embodiment of a braking system.

[0065] Unlike the embodiment of FIG. 9, first axle unit 10 of FIG. 10 has master brake cylinder shutoff valve 30 in its single connecting line 28. This single master brake cylinder shutoff valve 30 is preferably located in connecting line 28 between master brake cylinder 24 and the connecting line branch. In this way, configuring connecting line connections 42a and 42b as "compensating holes" and using specific seal member types can be omitted in first axle unit 10 of FIG. 10.

[0066] For other features and advantages of the braking system of FIG. 10, please refer to the embodiment of FIGS. 1 to 9 described above.

[0067] FIG. 11 shows a schematic partial view of an eleventh embodiment of a brake system.

[0068] Instead of a single master brake cylinder shutoff valve 30, first axle unit 10 of FIG. 11 includes a first master brake cylinder shutoff valve 30a located in a first section of branched connecting pipe 28 and a second master brake cylinder shutoff valve 30b located in a second section of branched connecting pipe 28. Accordingly, first axle unit 10 of FIG. 10 can also omit configuring connecting pipe communication portions 42a and 42b as "compensation holes" and using a specific seal member type.

[0069] For other features and advantages of the braking system of FIG. 11, please refer to the embodiment of FIGS. 1 to 10 described above.

[0070] FIG. 12 shows a schematic partial view of a twelfth embodiment of a brake system.

[0071] 12, the master brake cylinder 24 is also a tandem-type master brake cylinder 24, whose first chamber is connected to the first chamber of the piston-cylinder device 12 via a first connecting pipe 28a and a first connecting pipe communication part 42a, and whose second chamber is connected to the second chamber of the piston-cylinder device 12 via a second connecting pipe 28b and a second connecting pipe communication part 42b. In the brake system of FIG. 12, each connecting pipe communication part 42a and 42b is also configured as a "compensating hole," so that brake fluid can be transferred from the master brake cylinder 24 to the respective chamber of the piston-cylinder device 12 when the adjacent pistons of the piston-cylinder device 12 are in their respective initial positions, whereas each connecting pipe communication part 42a or 42b is sealed by at least one seal member 44a, 44b, or 44c when the adjacent pistons are adjusted from their respective initial positions. Additionally, each piston of the piston-cylinder unit 12 is equipped with a respective sealing member 44a, 44b and 44c already described above.

[0072] For other features and advantages of the braking system of FIG. 12, please refer to the embodiment of FIGS. 1 to 11 described above.

[0073] FIG. 13 shows a schematic partial view of a thirteenth embodiment of a brake system.

[0074] Unlike the embodiment of Figure 12, first axle unit 10 of Figure 13 has one master brake cylinder shutoff valve 30a or 30b in each connecting pipe 28a or 28b, respectively. Therefore, first axle unit 10 of Figure 13 can also omit configuring connecting pipe communication portions 42a and 42b as "compensating holes" and using a specific seal member type.

[0075] For other features and advantages of the braking system of FIG. 13, please refer to the embodiment of FIGS. 1 to 12 described above.

[0076] 1, 2, 7 and 8, the first axle unit has only one brake circuit including at least the first wheel brake cylinder 14a, the first outlet valve 18a, the second wheel brake cylinder 14b and the second outlet valve 18b, and the motor-type brake pressure generator 12 is integrated into or hydraulically connected to the brake circuit. Thus, the first axle unit 10 in the embodiments of FIGS. 1, 2, 7 and 8 is a single-circuit axle unit 10. 3 to 6 and 9 to 13 described above have a first brake circuit of the first axle unit 10 with at least the first wheel brake cylinder 14a and the first outlet valve 18a, and a second brake circuit of the first axle unit 10 with at least the second wheel brake cylinder 14b and the second outlet valve 18b, the first brake circuit being hydraulically connected to the first chamber of the piston-cylinder arrangement 12, and the second brake circuit being hydraulically connected to the second chamber of the piston-cylinder arrangement 12. In this way, the first axle unit 10 may alternatively be configured as a two-circuit arrangement.

[0077] Optionally, in each of the above-described embodiments, the first axle unit 10 may further include a control device designed and / or programmed to control at least the motor-driven brake pressure generator 12, the first discharge valve 18a, and the second discharge valve 18b, and possibly at least one other valve 20a, 20b, 30, 30a, 30b, 32, 32a, and 32b of the first axle unit 10, by means of at least one control signal, taking into account at least one brake setting signal. The at least one brake setting signal may be output to the control device from at least one brake operating element sensor of the vehicle, an automatic speed control device of the vehicle, another control device of the second axle unit, and / or another stabilization device of the brake system. The at least one brake operating element sensor may be, for example, a rod stroke sensor and / or a stroke difference sensor. The automatic speed control device may be, for example, an automatic device for unmanned vehicle driving, adaptive cruise control, and / or an emergency braking system. Further vehicle stabilization devices can be understood to be, in particular, ESP control units or ABS control units. Thus, the first axle unit 10 can cooperate with a large number of different electronic components for pressure regulation in the wheel brake cylinders 14a and 14b.

[0078] In a preferred development, the control device may be configured to receive and evaluate sensor signals from a (not shown) feed pressure sensor of the first axle unit 10, at least one (not shown) wheel pressure sensor of the first axle unit 10, at least one (not shown) wheel rotation speed sensor, a yaw rate sensor, and / or at least one acceleration sensor of a wheel of the first axle of the vehicle. Similarly, the control device may be designed to jointly control at least one (not shown) motor of the vehicle that is used as a generator for regenerative braking of the vehicle or to transmit information favorable for regenerative braking of the vehicle to the motor.

[0079] FIG. 14 shows a flow chart illustrating an embodiment of a method for braking a vehicle with at least two axles.

[0080] The method described below can be implemented, for example, with the brake system described above. However, the applicability of the method is not limited to the use of one such brake system, nor is the applicability of the method limited to a specific vehicle model / vehicle type of two-axle vehicle / car.

[0081] In method step S1, a first wheel of a first axle and a second wheel of the first axle of the vehicle are braked by actuating at least one motorized brake pressure generating device of a first axle unit mounted on the first axle to transfer brake fluid from a connected brake fluid reservoir to a first wheel brake cylinder associated with the first wheel of the first axle and to a second wheel brake cylinder associated with a second wheel of the first axle. Simultaneously with method step S1, method step S2 can also be performed, in which a first wheel of a second axle and a second wheel of a second axle of the vehicle are braked by actuating a second axle unit mounted on the second axle and hydraulically separated from the first axle unit. The method further includes a method step S3, in which brake fluid is discharged from the first wheel brake cylinder via the first discharge valve to the connected brake fluid reservoir, and from the second wheel brake cylinder via the second discharge valve to the connected brake fluid reservoir. Accordingly, implementing the method described herein also provides the advantages described above. [Explanation of symbols]

[0082] 10 First axle unit 12 Motor-driven brake pressure generating device 14a First wheel brake cylinder 14b Second wheel brake cylinder 16 Brake fluid reservoir 18a First discharge valve 18b Second discharge valve 22a Third check valve 22b Fourth check valve 24 Master brake cylinder 26 Brake operating member 28, 28a, 28b Connection piping 31 Communication part 34 Connecting Area 36a First check valve 36b Second check valve 42, 42a, 42b Connection pipe communication part

Claims

1. 1. A braking system for a vehicle having at least two axles, comprising: The vehicle has a first axle unit (10) that is mountable or mounted on a first axle of the vehicle and that includes a motor-driven brake pressure generating device (12), a first wheel brake cylinder (14a), and a second wheel brake cylinder (14b), and the motor-driven brake pressure generating device (12) is operable to transfer brake fluid from a connected brake fluid reservoir (16) to the first wheel brake cylinder (14a) and the second wheel brake cylinder (14b), thereby braking a first wheel of the first axle associated with the first wheel brake cylinder (14a) and a second wheel brake cylinder (14b), and A braking system comprising a second axle unit hydraulically separated from the first axle unit (10) that can be mounted or is mounted on a second axle of the vehicle, whereby a first wheel of the second axle and a second wheel of the second axle can be braked by operation of the second axle unit, the first axle unit (10) includes a first discharge valve (18a) associated with the first wheel brake cylinder (14a) and a second discharge valve (18b) associated with the second wheel brake cylinder (14b), and is capable of discharging brake fluid from the first wheel brake cylinder (14a) via the first discharge valve (18a) and from the second wheel brake cylinder (14b) via the second discharge valve (18b) to the connected brake fluid reservoir (16); The first axle unit (10) additionally includes a master brake cylinder (24), to which a brake operating member (26) of the vehicle can be connected or which is connected, so that at least one piston of the master brake cylinder (24), which defines at least one chamber of the master brake cylinder (24), can be adjusted in position by operation of the brake operating member (26) by a driver of the vehicle, and brake fluid can be transferred from the at least one chamber of the master brake cylinder (24) to at least the first wheel brake cylinder (14a) and / or the second wheel brake cylinder (14b) via at least one valveless or valve-equipped connecting pipe (28, 28a, 28b); The first discharge valve (18a) is hydraulically connected to the second discharge valve (18b) via a connection section (34), and a single valveless or valve-equipped connecting pipe (28) communicates with the connection section (34), and a first check valve (36a) arranged in parallel with the first discharge valve (18a) controls the transfer of brake fluid from the first wheel brake cylinder (14a) to the communication section (31) of the connecting pipe (28) to the connection section (34). and / or a second check valve (36b) arranged in parallel with the second discharge valve (18b) is oriented in such a direction that brake fluid transfer from the second wheel brake cylinder (14b) to the communication portion (31) of the connecting pipe (28) to the connection section (34) is prevented by the second check valve (36b).

2. 2. The brake system according to claim 1, wherein the brake circuit of the first axle unit (10) includes at least the first wheel brake cylinder (14 a), the first discharge valve (18 a), the second wheel brake cylinder (14 b), and the second discharge valve (18 b), and the motor-type brake pressure generating device (12) is incorporated into the brake circuit or is hydraulically connected to the brake circuit.

3. 2. The brake system according to claim 1, wherein a first brake circuit of the first axle unit includes at least the first wheel brake cylinder and the first discharge valve, a second brake circuit of the first axle unit includes at least the second wheel brake cylinder and the second discharge valve, the first brake circuit being hydraulically connected to a first chamber of the motor-type brake pressure generating device configured as a piston-cylinder device, and the second brake circuit being hydraulically connected to a second chamber of the piston-cylinder device.

4. 4. The brake system according to claim 1, wherein the first axle unit (10) is hydraulically isolated from the second axle unit (10) such that the first axle unit (10) and the second axle unit (10) are connected to each other via at least one signal line and / or bus line.

5. The motor-driven brake pressure generating device (12) is a piston-cylinder device (12) having at least one chamber, and the master brake cylinder (24) is hydraulically connected to the piston-cylinder device (12) through at least one valveless or valve-equipped connecting pipe (28, 28a, 28b), such that the at least one connecting pipe (28, 28a, 28b) has one connecting pipe communication part (42, 42a, 42b) respectively to at least one chamber of the piston-cylinder device (12), and the at least one connecting pipe communication part (42, 42a, 42b) connects the master brake cylinder (24) to at least one connecting pipe (28, 28a, 28b) and its respective connection part when at least one position-adjustable piston of the piston-cylinder device (12) is in its respective initial position.

2. The brake system of claim 1, wherein brake fluid can be transferred to the at least one chamber of the piston-cylinder device via a connecting pipe connection, and wherein, when at least one adjustable piston is displaced from its initial position, transfer of brake fluid from the master brake cylinder to the at least one chamber of the piston-cylinder device via the at least one connecting pipe and its respective connecting pipe connection is prevented by at least one sealing element mounted on a surface of the at least one adjustable piston of the piston-cylinder device and / or in the at least one chamber of the piston-cylinder device.

6. A brake system as described in any one of claims 1 to 3, wherein the first wheel brake cylinder (14a) is hydraulically connected to the motor-operated brake pressure generating device (12) via a first isolation valve (20a), and / or the second wheel brake cylinder (14b) is hydraulically connected to the motor-operated brake pressure generating device (12) via a second isolation valve (20b).

7. A brake system as described in claim 6, wherein a third check valve (22a) arranged in parallel to the first isolation valve (20a) is oriented in a direction such that the transfer of brake fluid from the first wheel brake cylinder (14a) in the direction of the motor-operated brake pressure generating device (12) is prevented by the third check valve (22a), and / or a fourth check valve (22b) arranged in parallel to the second isolation valve (20b) is oriented in a direction such that the transfer of brake fluid from the second wheel brake cylinder (14b) in the direction of the motor-operated brake pressure generating device (12) is prevented by the fourth check valve (22b).

Images