Abstract
A bistable solenoid valve for a hydraulic braking system includes a magnetic assembly and a guide sleeve in which a pole core is fixedly arranged and in which a valve armature is arranged for axial movement. The valve armature has a permanent magnet that is polarized in a direction of motion thereof. The magnetic assembly is slid onto the pole core and the guide sleeve, and the pole core forms an axial stop for the valve armature. The permanent magnet is injected or mounted in a magnet receptacle at an end face of the valve armature facing the pole core. The valve armature is configured to be driven by a magnetic force of the magnetic assembly and/or the permanent magnet so as to force a closing element into a valve seat during a closing motion and to lift the closing element out of the valve seat during an opening motion.
Claims
1. A bistable solenoid valve for a hydraulic braking system, comprising: a magnet assembly; a guide sleeve; a pole core fixedly arranged in the guide sleeve, the magnet assembly pushed onto the pole core and the guide sleeve; and a valve armature axially displaceably arranged in the guide sleeve, the valve armature having a permanent magnet that is polarized in a movement direction thereof, the pole core defining an axial stop for the valve armature, wherein the valve armature is configured to be driven by one or more of a magnetic force generated by the magnet assembly and a magnetic force of the permanent magnet and pushes a closing element into a valve seat during a closing movement and raises the closing element off the valve seat during an opening movement, and wherein the valve armature is configured as a plastic component, and the permanent magnet is embedded or mounted in a magnet receptacle on a first end face of the valve armature facing toward the pole core.
2. The bistable solenoid valve as claimed in claim 1, wherein the valve armature comprises at least two equalizing grooves and at least two ribs, which are each arranged between two adjacent equalizing grooves and partially enclose the permanent magnet.
3. The bistable solenoid valve as claimed in claim 2, wherein an end of each of the ribs partially enclosing the permanent magnet is respectively configured as a cover, the permanent magnet embedded in the cover.
4. The bistable solenoid valve as claimed in claim 2, wherein an end of each of the ribs partially enclosing the permanent magnet is respectively configured as a catch hook, the catch hook locked with the permanent magnet.
5. The bistable solenoid valve as claimed in claim 4, wherein the catch hooks each comprise an insertion bevel via which the permanent magnet is installable.
6. The bistable solenoid valve as claimed in claim 1, wherein the permanent magnet is held on the pole core in a deenergized open position of the solenoid valve, so that an air gap between pole core and valve armature is minimal and the closing element is raised off the valve seat.
7. The bistable solenoid valve as claimed in claim 1, wherein the magnet assembly is energized during the closing movement in a first current direction, which generates a first magnetic field, which causes the pole core to repel the permanent magnet with the valve armature so that an air gap between the valve armature and the pole core is enlarged and the closing element is pushed into the valve seat.
8. The bistable solenoid valve as claimed in claim 1, wherein a restoring spring is arranged between the pole core and the valve armature, and wherein a spring force of the restoring spring assists the closing movement.
9. The bistable solenoid valve as claimed in claim 1, wherein, in a deenergized closed position of the solenoid valve, one or more of a pressure confined in the solenoid valve and a restoring spring arranged between the pole core and the valve armature hold the closing element in the valve seat to form a seal.
10. The bistable solenoid valve as claimed in claim 1, wherein the permanent magnet moves the valve armature in a direction of the pole core during the opening movement if a pressure confined in the solenoid valve falls below a pre-determinable limiting value so that an air gap between the valve armature and the pole core is reduced in size and the closing element is raised off the valve seat.
11. The bistable solenoid valve as claimed in claim 1, wherein the magnet assembly is energized during the opening movement in a second current direction, which generates a second magnetic field, which causes the pole core and the permanent magnet with the valve armature to attract one another so that an air gap between the valve armature and the pole core is reduced in size and the closing element is raised off the valve seat.
12. The bistable solenoid valve as claimed in claim 1, wherein the permanent magnet is arranged independently of a stroke of the valve armature within the magnet assembly.
13. A hydraulic braking system for a vehicle, comprising: a hydraulic unit and a plurality of wheel brakes, the hydraulic unit including at least one brake circuit configured to carry out a wheel-individual brake pressure regulation, wherein the at least one brake circuit includes at least one solenoid valve and at least one bistable solenoid valve, the bistable solenoid valve including: a magnet assembly, a guide sleeve, a pole core fixedly arranged in the guide sleeve, the magnet assembly pushed onto the pole core and the guide sleeve, and a valve armature axially displaceably arranged in the guide sleeve, the valve armature having a permanent magnet that is polarized in a movement direction thereof, the pole core defining an axial stop for the valve armature, wherein the valve armature is configured to be driven by one or more of a magnetic force generated by the magnet assembly and a magnetic force of the permanent magnet and pushes a closing element into a valve seat during a closing movement and raises the closing element off the valve seat during an opening movement, and wherein the valve armature is configured as a plastic component, and the permanent magnet is embedded or mounted in a magnet receptacle on a first end face of the valve armature facing toward the pole core.
14. The hydraulic braking system as claimed in claim 13, wherein the at least one bistable solenoid valve (i) releases a brake pressure regulation in at least one associated wheel brake in a deenergized open position and (ii) confines a present brake pressure in the at least one associated wheel brake in a deenergized closed position.
15. The hydraulic braking system as claimed in claim 13, wherein the at least one brake circuit comprises: a fluid pump, a suction valve, that connects a suction line of the fluid pump to a muscle-power-actuated master cylinder during a brake pressure regulation and disconnects the suction line of the fluid pump from the muscle-power-actuated master cylinder in a normal mode, and a switchover valve that connects the muscle-power-actuated master cylinder to at least one associated wheel brake in the normal mode and retains the system pressure in the brake circuit during a brake pressure regulation.
16. The hydraulic braking system as claimed in claim 15, wherein one or more of the switchover valve and the suction valve are respectively configured as the bistable solenoid valve.
17. The hydraulic braking system as claimed in claim 13, wherein the at least one brake circuit comprises: a hydraulic pressure generator, the pressure of which is configured to be set via a servo motor, a simulator valve that connects a pedal simulator to a muscle-power-actuated master cylinder in a normal mode and disconnects the pedal simulator from the master cylinder in an emergency mode and during a brake pressure regulation, a brake circuit disconnecting valve that connects the muscle-power-actuated master cylinder to at least one associated wheel brake in the emergency mode and disconnects the muscle-power-actuated master cylinder from the at least one associated wheel brake in the normal mode and during a brake pressure regulation, and a pressure switching valve that connects the hydraulic pressure generator to the at least one associated wheel brake in the normal mode and during a brake pressure regulation and disconnects the hydraulic pressure generator from the at least one associated wheel brake in the emergency mode.
18. The hydraulic braking system as claimed in claim 17, wherein one or more of the simulator valve, the brake circuit disconnecting valve, and the pressure switching valve are respectively configured as the bistable solenoid valve.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 shows a schematic sectional illustration of a first exemplary embodiment of a bistable solenoid valve according to the invention in the open position.
[0023] FIG. 2 shows a schematic sectional illustration of the bistable solenoid valve according to the invention from FIG. 1 in the closed position.
[0024] FIG. 3 shows a schematic sectional illustration of a detail of the bistable solenoid valve according to the invention from FIGS. 1 and 2 in the region of the magnet assembly during the closing movement.
[0025] FIG. 4 shows a schematic sectional illustration of the detail of the bistable solenoid valve according to the invention from FIG. 3 during the opening movement.
[0026] FIG. 5 shows a schematic sectional illustration of a second exemplary embodiment of a bistable solenoid valve according to the invention in the closed position.
[0027] FIG. 6 shows a schematic perspective illustration of an exemplary embodiment of a valve armature for the bistable solenoid valve according to the invention from FIG. 5.
[0028] FIG. 7 shows a schematic perspective partially sectional illustration of the valve armature from FIG. 6.
[0029] FIG. 8 shows a schematic perspective partially sectional illustration of a section of the valve armature from FIGS. 6 and 7 facing toward a pole core.
[0030] FIG. 9 shows a schematic perspective partially sectional illustration of a section of a further exemplary embodiment of a valve armature facing toward the pole core for the bistable solenoid valve according to the invention from FIG. 5.
[0031] FIG. 10 shows a schematic circuit diagram of a first exemplary embodiment of a hydraulic braking system according to the invention.
[0032] FIG. 11 shows a schematic circuit diagram of a second exemplary embodiment of a hydraulic braking system according to the invention.
EMBODIMENTS OF THE INVENTION
[0033] As is apparent from FIGS. 1 to 9, the illustrated exemplary embodiments of a bistable solenoid valve 10A, 10B according to the invention for a hydraulic braking system 1A, 1B each comprise a magnet assembly 20A, 20B and a guide sleeve 13, in which a pole core 11 is arranged fixedly and a valve armature 40A, 40B, 40C having a permanent magnet 18, which is polarized in its movement direction, is arranged axially displaceably. The magnet assembly 20A, 20B is pushed onto the pole core 11 and the guide sleeve 13. The pole core 11 forms an axial stop for the valve armature 40A, 40B, 40C. Moreover, the valve armature 40A, 40B, 40C is drivable by a magnetic force generated by the magnet assembly 20A, 20B and/or by a magnetic force of the permanent magnet 18 and pushes a closing element 41 into a valve seat 15.1 during a closing movement and raises the closing element 41 off the valve seat 15.1 during an opening movement. In this case, the valve armature 40A, 40B, 40C is embodied as a plastic component, wherein the permanent magnet 18 is embedded or installed in a magnet receptacle 43A, 43B, 43C on a first end face of the valve armature 40A, 40B, 40C facing toward the pole core 11.
[0034] As is furthermore apparent from FIGS. 1 to 9, the valve armatures 40A, 40B, 40C each have four at least two equalizing grooves 42A, 42B, 42C and at least two ribs 44A, 44B, 44C, which are each arranged between two adjacent equalizing grooves 42A, 42B, 42C and partially enclose the permanent magnet 18. In the illustrated exemplary embodiments, the valve armatures 40A, 40B, 40C each have four equalizing grooves 42A, 42B, 42C embodied as axial grooves and four ribs 44A, 44B, 44C. This enables a rapid pressure equalization in the air gap 12 between the pole core 11 and the valve armature 40A, 40B, 40C even at low temperatures, so that a reduced switching time results.
[0035] As is furthermore apparent from FIGS. 1 to 8, an end of the individual ribs 44A, 44B partially enclosing the permanent magnet 18 is respectively embodied as a cover 45A, 45B, in which the permanent magnet 18 is embedded, in the illustrated exemplary embodiments of the valve armature 40A, 40B. In these exemplary embodiments of the valve armature 40A, 40B, the permanent magnet is inserted, for example, in a plastic injection molding procedure as an insert part into a corresponding mold during the production of the valve armature 40A, 40B and is permanently bonded thereto during the production of the valve armature 40A, 40B.
[0036] As is furthermore apparent from FIG. 9, an end of the individual ribs 44C partially enclosing the permanent magnet 18 is respectively embodied as a catch hook 45C, which is locked with the permanent magnet 18, in the illustrated alternative exemplary embodiment of the valve armature 40C. The catch hooks 45 are extruded in the axial direction on the ribs 44C and each have an insertion bevel 45.1C, via which the permanent magnet 18 can be easily installed. During the installation of the permanent magnet 18, it is moved via the insertion bevels 45.1C and the catch hooks 45C move slightly outward until the permanent magnet 18 is seated in a final position. The catch hooks 45C then snap back into the starting positions thereof and securely hold the valve armature 40C in its operating position.
[0037] A cavity then also results between valve armature 40A, 40B, 40C and pole core 11 due to the covers 45A, 45B or catch hooks 45C formed between the pole core 11 and the permanent magnet 18 when the valve armature 40A, 40B, 40C presses against the pole core 11 in the open position via the covers 45A, 45B or the catch hooks 45C. Due to this cavity between the valve armature 11 and the pole core 11 and the equalizing grooves 42A, 42B, 42C, a faster pressure equalization is enabled in the air gap 12 between valve armature 40A, 40B, 40C and pole core 11, since a direct fluid connection is provided between the equalizing grooves 42A, 42B, 42C of the valve armature 40A, 40B, 40C and the end face of the valve armature 40A, 40B, 40C or the permanent magnet 18, respectively. An improvement of the closing time, in particular at low temperatures, can thus advantageously be achieved, by the so-called hydraulic sticking between the pole core 11 and the valve armature 40A, 40B, 40C being reduced by the fluid connection, and also a buildup of a closing fluidic counterforce on the first end face of the armature being promoted by rapid propagation of the fluid. Moreover, the covers 45A, 45B or catch hooks 45C act as damping elements, so that no damage to the permanent magnet 18 results due to the impact of the permanent magnet 18 on the pole core 11.
[0038] As is furthermore apparent from FIGS. 1 to 5, a hat-shaped valve sleeve 15 having a valve seat 15.1, which is arranged between at least one first flow opening 15.2 and at least one second flow opening 15.3, is connected to the guide sleeve 13. The solenoid valve 10A, 10B is caulked via a caulking disk 14 with a receptacle borehole of a fluid block 30, which comprises multiple fluid ducts 34, 36. As is furthermore apparent from FIGS. 1 to 5, a first flow opening 15.2, on the inner edge of which the valve seat 15.1 is formed, is introduced into a bottom of the hat-shaped valve sleeve 15 and fluidically connected to a first fluid duct 34. The at least one second flow opening 15.2 is introduced as a radial borehole into the lateral jacket surface of the hat-shaped valve sleeve 15 and is fluidically connected to a second fluid duct 36.
[0039] As is furthermore apparent from FIGS. 1 to 7, the closing element 41 is embodied as a ball in the illustrated exemplary embodiments and is pressed into a receptacle in the valve armature 40A, 40B, 40C, which is arranged on a second end face of the valve armature 40A, 40B, 40C facing toward the valve seat 15.1.
[0040] As is furthermore apparent from FIGS. 1 to 5, in each of the illustrated exemplary embodiments, the magnet assembly 20A, 20B comprises a hood-shaped housing jacket 22A, 22B, a winding body 24A, 24B, on which a coil winding 26A, 26B is applied, and a cover disk 28A, 28B, which terminates the hood-shaped housing jacket 22 on its open side. The coil winding 26A, 26B can be energized via two electrical contacts 27, which are led out of the housing jacket 22A, 22B. As is furthermore apparent from FIGS. 1 to 5, the permanent magnet 18 is arranged independently of the armature stroke inside the magnet assembly 20A, 20B.
[0041] As is furthermore apparent from FIGS. 1 to 5, in the illustrated exemplary embodiments of a bistable solenoid valve 10A, 10B, a restoring spring 16 is arranged between the pole core 11 and the valve armature 40A, 40B, 40C. In this case, a spring force of the restoring spring 16 can assist the closing movement of the valve armature 40A, 40B, 40C and/or the closing element 41. The valve behavior can be influenced via the selected spring force of the restoring spring 16, and a larger stroke or air gap 12 can also be bridged. As is furthermore apparent from FIGS. 1 to 5, in the illustrated exemplary embodiment, the restoring spring 16 is at least partially accommodated by a spring receptacle 46, which is introduced as a borehole into the valve armature 40A, 40B, 40C. As is furthermore apparent from FIGS. 1 to 9, the permanent magnet 18 is embodied in each of the illustrated exemplary embodiments as a circular perforated disk, which the restoring spring 16 penetrates. Alternatively, the permanent magnet 18 can be embodied as a polygonal perforated plate. In alternative exemplary embodiment (not shown), the spring receptacle 46 can be introduced as a borehole into the pole core 11. In this exemplary embodiment, the permanent magnet 18 can then be embodied as a disk or as a plate without holes. Moreover, both the pole core 11 and also the valve armature 40A, 40B, 40C can comprise a spring receptacle 19, which at least partially accommodate the restoring spring 16.
[0042] As is furthermore apparent from FIG. 1, the permanent magnet 18 holds itself in the illustrated deenergized open position of a first exemplary embodiment of the solenoid valve 10A on the pole core 11, so that an air gap 12 between pole core 11 and valve armature 40A is minimal and the closing element 41 is raised off the valve seat 15.1.
[0043] As is furthermore apparent from FIG. 2, in the illustrated first exemplary embodiment, a pressure confined in the solenoid valve 10A and the restoring spring 16 holds the closing element 41 in the valve seat 15.1 in the illustrated deenergized closed position to form a seal. In the illustrated exemplary embodiment, the magnetic force of the permanent magnet 18 is less than the acting closing force, which the confined pressure and/or the restoring spring 16 generate.
[0044] As is furthermore apparent from FIG. 3, the magnet assembly 20A is energized to close the solenoid valve 10A during the closing movement using a first current direction, which generates a first magnetic field 29A, which causes the pole core 11 to repel the permanent magnet 18 with the valve armature 40A, so that the air gap 12 between the valve armature 40A and the pole core 11 enlarges and the closing element 41 is pushed into the valve seat 15.1. Moreover, the spring force of the restoring spring 16 assists the closing movement of the valve armature 40A and/or the closing element 41.
[0045] As is furthermore apparent from FIG. 4, the magnet assembly 20A is energized to open the solenoid valve 10A during the opening movement using a second current direction, which generates a second magnetic field 29B, which causes the pole core 11 and the permanent magnet 18 with the valve armature 40A to attract one another, so that the air gap 12 between the valve armature 40A and the pole core 11 is reduced in size and the closing element 41 is raised off the valve seat 15.1. This means that the current flow through the magnet assembly 20A during the opening of the solenoid valve 10A is simply reversed in polarity in comparison to the closing of the solenoid valve 10A.
[0046] Alternatively, the magnetic force of the permanent magnet can be predetermined so that to open the solenoid valve 10A, the permanent magnet 18 moves the valve armature 40A in the direction of the pole core 11 during the opening movement if the pressure confined in the solenoid valve 10A sinks below a pre-determinable limiting value, so that the air gap 12 between the valve armature 40A and the pole core 11 is reduced in size and the closing element 41 is raised off the valve seat 15.1. In this embodiment, the solenoid valve 10A changes from the closed position into the open position without energizing of the magnet assembly 20A in dependence on the active hydraulic force and/or the confined pressure. This means that the magnetic force of the permanent magnet 18 is greater than the acting closing force, which the confined pressure and/or the restoring spring 16 generate if the confined pressure falls below the predetermined limiting value.
[0047] As is furthermore apparent from FIG. 5, an illustrated second exemplary embodiment of the solenoid valve 10B is embodied shorter than the first exemplary embodiment of the solenoid valve 10A with identical functionality. As is furthermore apparent from FIG. 5, in the illustrated second exemplary embodiment of the solenoid valve 10B, similarly to the first exemplary embodiment of the solenoid valve 10A, a pressure confined in the solenoid valve 10B and the restoring spring 16 retain the closing element 41 in the valve seat 15.1 in the illustrated deenergized closed position to form a seal. In the illustrated second exemplary embodiment, the magnetic force of the permanent magnet 18 is less than the acting closing force, which the confined pressure and/or the restoring spring 16 generate. As is furthermore apparent from FIG. 5, the magnet assembly 20B having the hood-shaped housing jacket 22B, the winding body 24B, the coil winding 26B, and the cover disk 28B is embodied shorter in the illustrated second exemplary embodiment of the solenoid valve 10B than the magnet assembly 20A of the first exemplary embodiment. The guide sleeve 13B and the valve armature 40B of the illustrated second exemplary embodiment of the solenoid valve 10B are also embodied shorter than the guide sleeve 13A and the valve armature 40A of the first exemplary embodiment of the solenoid valve 10A. The embodiment of the hat-shaped valve sleeve having the valve seat 15.1, the at least one first flow opening 15.2, and the at least one second flow opening 15.3 of the illustrated second exemplary embodiment corresponds to the embodiment of the valve sleeve 15 of the first exemplary embodiment of the solenoid valve 10A. The illustrated second exemplary embodiment corresponds to a compact cost-effective solenoid valve 10B, which requires a reduced installation space and less electrical power for switching.
[0048] In an alternative exemplary embodiment (not shown) of a bistable solenoid valve, in contrast to the illustrated exemplary embodiments of the bistable solenoid valve 10A, 10B, a restoring spring 16 is not arranged between the pole core 11 and the valve armature 40A, 40B, 40C. The permanent magnet 18 is then embodied in this exemplary embodiment as a circular disk or as a polygonal plate. Similarly to the illustrated exemplary embodiments, the permanent magnet 18 is retained on the pole core 11 in the deenergized open position of the exemplary embodiment (not shown) of the solenoid valve, so that the air gap 12 between pole core 11 and valve armature 40A, 40B, 40C is minimal and the closing element 41 is raised off the valve seat 15.1. For closing, the magnet assembly 20A, 20B of the solenoid valve (not shown) is energized during the closing movement using a first current direction, which generates the first magnetic field, which causes the pole core 11 to repel the permanent magnet 18 with the valve armature 40A, 40B, 40C, so that the air gap 12 between the valve armature 40A, 40B, 40C and the pole core 11 is enlarged and the closing element 41 is pushed into the valve seat 15.1. In contrast to the illustrated exemplary embodiments of the solenoid valve 10A, 10B, in the exemplary embodiment of the solenoid valve (not shown) only a pressure confined in the solenoid valve holds the closing element 41 in the valve seat 15.1 to form a seal. To open the solenoid valve, the magnet assembly 20A, 20B is energized during the opening movement using a second current direction, which generates a second magnetic field, which causes the pole core 11 and the permanent magnet 18 with the valve armature 40A, 40B, 40C to attract one another, so that the air gap 12 between the valve armature 40A, 40B, 40C and the pole core 11 is reduced in size and the closing element 41 is raised off the valve seat 15.1.
[0049] Alternatively, the magnetic force of the permanent magnet can be predetermined so that to open the solenoid valve, the permanent magnet 18 moves the valve armature 40A, 40B, 40C in the direction of the pole core 11 during the opening movement if the pressure confined in the solenoid valve sinks below a pre-determinable limiting value, so that the air gap 12 between the valve armature 40A, 40B, 40C and the pole core 11 is reduced in size and the closing element 41 is raised off the valve seat 15.1. In this embodiment, the solenoid valve changes from the closed position into the open position without energizing of the magnet assembly 20A, 20B in dependence on the active hydraulic force and/or on the confined pressure. This means that the magnetic force of the permanent magnet 18 is greater than the acting closing force which the confined pressure generates when the confined pressure falls below the predetermined limiting value.
[0050] As is furthermore apparent from FIGS. 10 and 11, the illustrated exemplary embodiments of a hydraulic braking system 1A, 1B for a vehicle each comprise a hydraulic unit 9A, 9B and multiple wheel brakes RR, FL, FR, RL. The hydraulic unit 9A, 9B comprises at least one brake circuit BC1A, BC2A, BC1B, BC2B, which comprises at least one solenoid valve HSV1, HSV2, USV1, USV2, EV1, EV2, EV3, EV4, AV1, AV2, AV3, AV4, SSV, CSV1, CSV2, PSVT, PSV2, TSV and carries out a wheel-individual brake pressure regulation. In this case, the at least one brake circuit BC1A, BC2A, BC1B, BC2B comprises at least one bistable solenoid valve 10A, 10B.
[0051] As is apparent from FIGS. 10 and 11, the illustrated exemplary embodiments of a hydraulic braking system 1A, 1B according to the invention for a vehicle, using which various safety functions can be executed, each comprise a master cylinder 5A, 5B, a hydraulic unit 9A, 9B, and multiple wheel brakes RR, FL, FR, RL. As is furthermore apparent from FIGS. 10 and 11, the illustrated exemplary embodiments of the hydraulic braking system 1A, 1B each comprise two brake circuits BC1A, BC2A, BC1B, BC2B, which are each associated with two of the four wheel brakes RR, FL, FR, RL. Thus, a first wheel brake RR, which is arranged, for example, on a vehicle rear axle on the right side, and a second wheel brake FL, which is arranged, for example, on the vehicle front axle on the left side, are associated with a first brake circuit BC1A, BC1B. A third wheel brake FR, which is arranged, for example, on a vehicle front axle on the right side, and a fourth wheel brake RL, which is arranged, for example, on a vehicle rear axle on the left side, are associated with a second brake circuit BC2A, BC2B. Each wheel brake RR, FL, FR, RL is associated with an inlet valve EV1, EV2, EV3, EV4 and an outlet valve AV1, AV2, AV3, AV4, wherein pressure can be built up in the respective corresponding wheel brake RR, FL, FR, RL via the inlet valves EV1, EV2, EV3, EV4, and wherein pressure can be dissipated in the respective corresponding wheel brake RR, FL, FR, RL via the outlet valves AV1, AV2, AV3, AV4. For pressure buildup in the respective wheel brake RR, FL, FR, RL, the corresponding inlet valve EV1, EV2, EV3, EV4 is opened and the corresponding outlet valve AV1, AV2, AV3, AV4 is closed. For pressure dissipation in the respective wheel brake RR, FL, FR, RL, the corresponding inlet valve EV1, EV2, EV3, EV4 is closed and the corresponding outlet valve AV1, AV2, AV3, AV4 is opened.
[0052] As is furthermore apparent from FIGS. 10 and 11, a first inlet valve EV1 and a first outlet valve AV1 are associated with the first wheel brake RR, a second inlet valve EV2 and a second outlet valve AV2 are associated with the second wheel brake FL, a third inlet valve EV3 and a third outlet valve AV3 are associated with the third wheel brake FR, and a fourth inlet valve EV4 and a fourth outlet valve AV4 are associated with the fourth wheel brake RL. Control and/or regulating procedures for implementing safety functions can be carried out via the inlet valves EV1, EV2, EV3, EV4 and the outlet valves AV1, AV2, AV3, AV4.
[0053] As is furthermore apparent from FIG. 10, in the first exemplary embodiment of the hydraulic braking system 1A, the first brake circuit BC1A comprises a first suction valve HSV1, a first switchover valve USV1, a first compensation container AC1 having a first check valve RVR1, and a first fluid pump RFP1. The second brake circuit BC2A comprises a second suction valve HSV2, a second switchover valve USV2, a second compensation container AC2 having a second check valve RVR2, and a second fluid pump RFP2, wherein the first and second fluid pump RFP1, RFP2 are driven by a common electric motor M. Furthermore, the hydraulic unit 9A comprises sensor units (not shown) for ascertaining the present system pressure or brake pressure. The hydraulic unit 9A uses the first switchover valve USV1, the first suction valve HSV1, and the first recirculating pump RFP1 in the first brake circuit BC1A and the second switchover valve USV2, the second suction valve HSV2, and the second recirculating pump RFP2 in the second brake circuit BC2A for the brake pressure regulation and for implementing an ASR function and/or an ESP function. As is furthermore apparent from FIG. 10, each brake circuit BC1A, BC2A is connected to the master cylinder 5A, which can be actuated via a brake pedal 3A. Moreover, a fluid container 7A is connected to the master cylinder 5A. The suction valves HSV1, HSV2 enable an engagement in the braking system without a driver intention being present. For this purpose, the respective suction path for the corresponding fluid pump RFP1, RFP2 to the master cylinder 5A is opened via the suction valves HSV1, HSV2, so that it can provide the required pressure for the regulation instead of the driver. The switchover valves USV1, USV2 are arranged between the master cylinder 5A and at least one associated wheel brake RR, FL, FR, RL and set the system pressure or brake pressure in the associated brake circuit BC1A, BC2A. As is furthermore apparent from FIG. 10, a first switchover valve USV1 sets the system pressure or brake pressure in the first brake circuit BC1A and a second switchover valve USV2 sets the system pressure or brake pressure in the second brake circuit BC2A.
[0054] For this purpose, the at least two brake circuits BC1A, BC2A can each comprise a bistable solenoid valve 10A, 10B (not shown in greater detail), which has a deenergized closed position and a deenergized open position and is switchable between the two positions. Thus, for example, in each case a first bistable solenoid valve 10A, 10B can be looped into the respective brake circuit BC1A, BC2A in such a way that in the deenergized open position, it releases the brake pressure regulation in at least one associated wheel brake RR, FL, FR, RL and in the deenergized closed position, it confines a present brake pressure in the at least one associated wheel brake RR, FL, FR, RL. The first bistable solenoid valves 10A, 10B can be looped at various positions into the respective brake circuit BC1A, BC2A. Thus, the bistable solenoid valves 10A, 10B can be looped into the respective brake circuit BC1A, BC2A, for example, between the corresponding switchover valve USV1, USV2 and the inlet valves EV1, EV2, EV3, EV4 before an outlet duct of the corresponding fluid pump RFP1, RFP2. Alternatively, the bistable solenoid valves 10A, 10B can each be looped into the respective brake circuit BC1A, BC2A between the master cylinder 5A and the corresponding switchover valve USV1, USV2 directly before the corresponding switchover valve USV1, USV2. As a further alternative arrangement, the bistable solenoid valves 10A, 10B can each be looped into the respective brake circuit BC1A, BC2A between the corresponding switchover valve USV1, USV2 and the inlet valves EV1, EV2, EV3, EV4 after the outlet duct of the fluid pump RFP1, RFP2. Moreover, in a further alternative arrangement, the bistable solenoid valves 10A, 10B can each be looped into the respective brake circuit BC1A, BC2A between the master cylinder 5A and the corresponding switchover valve USV1, USV2 in the common fluid branch directly after the master cylinder 5A. Moreover, the bistable solenoid valves 10A, 10B can each be looped into the respective brake circuit BC1A, BC2A directly before an associated wheel brake RR, FL, FR, RL.
[0055] Moreover, in the illustrated exemplary embodiment, the two switchover valves USV1, USV2 and the two suction valves HSV1, HSV2 can each be embodied as a bistable solenoid valve 10A, 10B.
[0056] As is furthermore apparent from FIG. 11, the illustrated second exemplary embodiment of the hydraulic braking system 1B comprises, in contrast to the first exemplary embodiment, a hydraulic pressure generator ASP, the pressure of which can be set via a servo motor APM, and a pedal simulator PFS. The pressure generator ASP can be charged with fluid via a charging valve PRV from the fluid container 7B. As is furthermore apparent from FIG. 11, each brake circuit BC1B, BC2B is connected to the master cylinder 5B, which can be actuated via a brake pedal 3B. Moreover, a fluid container 7B is connected to the master cylinder 5B. Moreover, a chamber of the master cylinder 5B is coupled via a test valve TSV to the fluid container 7B. A simulator valve SSV connects the pedal simulator PFS to the muscle-power-actuated master cylinder 5B in normal operation and disconnects the pedal simulator PFS from the master cylinder 5B in the illustrated emergency mode and during a brake pressure regulation. The hydraulic unit 9B uses the hydraulic pressure generator ASP, and in the first brake circuit BC1B a first brake circuit disconnecting valve CSV1 and a first pressure switching valve PSV1, and in the second brake circuit BC2B a second brake circuit disconnecting valve CSV2 and a second pressure switching valve PSV2 for the brake pressure regulation and for implementing an ASR function and/or an ESP function. The pressure switching valves PSV1, PSV2 enable an engagement in the braking system without a driver intention being present. For this purpose, the pressure generator ASP is connected via the pressure switching valves PSV1, PSV2 to at least one associated wheel brake RR, FL, FR, RL, so that it can provide the required pressure for the regulation instead of the driver. As is furthermore apparent from FIG. 11, a first pressure switching valve PSV1 sets the system pressure or brake pressure in the first brake circuit BC1B and a second pressure switching valve PSV2 sets the system pressure or brake pressure in the second brake circuit BC2B. The brake circuit disconnecting valves CSV1, CSV2 connect the muscle-power-actuated master cylinder 5B to at least one associated wheel brake RR, FL, FR, RL in the illustrated emergency mode and disconnect the muscle-power-actuated master cylinder 5B from the at least one associated wheel brake RR, FL, FR, RL in the normal mode and during a brake pressure regulation. The pressure switching valves PSV1, PSV2 connect the hydraulic pressure generator ASP to the at least one associated wheel brake RR, FL, FR, RL in the normal mode and during a brake pressure regulation, and disconnect the hydraulic pressure generator ASP from the at least one associated wheel brake RR, FL, FR, RL in the emergency mode. Furthermore, the hydraulic unit 9B comprises multiple sensor units (not shown) for ascertaining the present system pressure or brake pressure. In the illustrated exemplary embodiment, the simulator valve SSV and the two pressure switching valves PSV1, PSV2 and one of the two brake circuit disconnecting valves CSV1, CSV2 are each embodied as bistable solenoid valves 10A, 10B. Since the present switching position is maintained in a bistable solenoid valve 10A, 10B in the event of failure of the vehicle electrical system and the bistable solenoid valves could also be deenergized closed at this moment, it is reasonable for the illustrated exemplary embodiment to replace only one of the two brake circuit disconnecting valves CSV1, CSV2 with a bistable solenoid valve 10A, 10B, so that in the event of a failure of the vehicle electrical system, the vehicle can be braked using one brake circuit BC1B, BC2B, since the conventional brake circuit disconnecting valve is embodied as a normally open solenoid valve and is held by its restoring spring in the open position.
[0057] In the illustrated hydraulic braking system 1B, the brake pressure in the normal driving mode is not conventionally generated by a vacuum brake booster assisted via the driver foot, but rather via the motor-operated pressure generator ASP. When the driver actuates the brake pedal 3B, this braking intention is sensed by the system via corresponding sensor units (not shown) and the simulator valve SSV and the pressure switching valves PSV1, PSV2 and the brake circuit disconnecting valves CSV1, CSV2 are switched simultaneously. The simulator valve SSV is switched over from the deenergized closed position into the deenergized open position. The driver thus displaces volume in the pedal simulator PFS and the driver receives haptic feedback about the braking procedure. The two brake circuit disconnecting valves CSV1, CSV2 are switched over from the deenergized open position into the deenergized closed position, whereby the brake lines from the master cylinder 5B are blocked. The pressure switching valves PSVT, PSV2 are switched over from the deenergized closed position into the deenergized open position, whereby the brake lines from the pressure generator ASP to the brake circuits BC1B, BC2B are opened and the pressure generator ASP can set the desired wheel-individual brake pressure.
