Actuating device

Abstract

Actuating device for a vehicle braking system, comprising: - a first piston-cylinder unit, at least one working chamber of which is to be connected or is connected to at least one wheel brake of the vehicle via at least one hydraulic line, - an electro-mechanical drive device and an actuating device, in particular a brake pedal, - an expansion tank which is hydraulically connected to the at least one working chamber, characterized in that a sensor device (31) is provided, wherein the sensor device (31) comprises at least one liquid level sensor (S5) in the form of a magnetic flux-sensitive sensor (S5, S5a) which detects at least one magnet (S5a) in a float of the expansion tank (13a), and wherein the magnetic flux-sensitive sensor comprises a Hall sensor (S5) for detecting the magnet (S5a) in the float.

Description

[0001] The invention relates to an actuating device for a vehicle braking system, a vehicle braking system and a vehicle State of the art

[0002] The trend in future braking and control systems is toward integrating all functions into a single unit. The focus here is on: • Error tolerance • Cost and weight • Functionality ABS / ESP and for all assistance functions • Size and length

[0003] Sensors are a key component that determines size and cost. The above-mentioned systems typically require at least sensors for pedal travel, engine rotation angle, pressure, brake fluid level, and possibly piston position. The signals from these sensors must be fed to an electronic control unit (ECU). Connecting them with a wiring harness and connector is complex and reduces reliability. The size is essentially determined by the pedal interface, actuator, and tandem master cylinder (TCM).

[0004] Travel simulators, as described in the applicant's DE 102008063771, or auxiliary pistons, as described in the applicant's DE 102010045617.9 (to which reference is hereby made), are often used in the pedal interface, which significantly determine the overall length. Furthermore, the pedal stroke, with a factor of 3.5, significantly determines the overall length. The sensors, preferably combined into a module (DE 102010045617.9), also determine the overall size if they are housed in the pedal interface.

[0005] Such vehicle braking systems are known, for example, from the following documents: DE 10 2009 014 614 A1, DE 10 2007 016 136 A1 DE 10 2007 032 501 A1.

[0006] Systems for detecting a liquid level in a container are known from DE 37 11 369 A1, US 2010 / 0 287 930 A1, JP 2002 - 370 554 A, DE 20 2006 011 113 U1, DE 10 2007 023 070 A1 or JP 2009 - 40 359 A.

[0007] Future vehicle concepts require short dimensions in both the footwell (pedal interface) and the aggregate or engine compartment (actuator + THZ). Object of the invention

[0008] The invention is based on the object of determining the level of brake fluid in an expansion tank in a simple manner. Solution to the task

[0009] This object is achieved by an actuating device according to claim 1.

[0010] The solution according to the invention provides an actuating device for a motor vehicle brake system which offers significant advantages over the known solutions with regard to structural conditions and also with regard to costs.

[0011] Advantageous embodiments and refinements of the invention emerge from the further claims, to which reference is made here.

[0012] The costs for the sensors, based on the combination of sensors on a circuit board in DE 10 2010045617.9 for angle of rotation and pedal travel sensors, can be reduced by expanding to include additional sensors and ultimately all sensors required for the braking system. These include the brake fluid level sensor, an additional position sensor for the piston position, and the integration of the brake light switch. This is currently used redundantly to the ESP pressure signal, since the "brake" signal is required for fail-safe operation by many systems, including the engine, transmission, and assistance functions.

[0013] Today, these sensors have a separate wiring harness to the corresponding ECU. It would be advantageous to replace all wiring harnesses with a direct connection via a plug connection from the sensor module to the ECU. The ECU itself would then only have one wiring harness for the power supply and the on-board power supply control unit. This also simplifies installation.

[0014] A reduction in the overall length of the integrated unit is achieved according to advantageous embodiments of the invention by: 1. Relocation of the sensor module from the pedal interface to the THZ or actuator with corresponding actuating elements through the motor. 2. Removal of all components such as the stepped piston and travel simulator from the pedal interface. This reduces the distance from the actuator to the pedal plate to just the pedal stroke. 3. Reducing the pedal stroke by increasing the pedal ratio.

[0015] Embodiments of the invention and its configurations are illustrated in the drawings and described in more detail below. Description of the characters

[0016] They show: Fig. 1 a structure of the actuating device from DE 10 2010045617.9 with relocation of the sensor module to the THZ, with direct electrical connection to the ECU; Fig. 2 a length-optimized interface with relocation of the auxiliary piston to the THZ, also with relocated sensor module; Fig. 2a the arrangement of the sensor module of the HCU and ECU parallel to the actuator; Fig. 3 a section through the stator with the position of the sensor shaft and actuating elements; Fig. 4 a section of the power transmission from the pedal to the actuating element with overforce protection; and Fig. 5 - 5a various circuits with integration of the brake light switch.

[0017] The Fig. 1, the actuating device for a motor vehicle brake comprises a brake pedal 1 with a pedal tappet 2. The pedal tappet 2 interacts via a prestressed elastic member 33a and flange sleeve 33 with an (auxiliary) piston 4, which is arranged axially displaceably in a cylinder and forms a working chamber connected to a travel simulator 17. The piston 4 has a central extension, which is sealed and guided in a partition wall of the cylinder. This central extension acts on a transmission tappet 11, which is connected rigidly via a coupling, in particular a magnetic coupling 12, but detachably via the coupling to a piston 18 of a piston-cylinder unit 13.

[0018] Axially adjacent to the cylinder 4a is a housing 5 of an externally powered actuator for brake boosting (BKV) and preferably pressure modulation for ABS, ESP, and the like. This actuator can, as in the example described here, comprise, for example, an electric motor with a stator 6 and rotor 7 arranged in the housing. The rotor 7, which is mounted in the housing 5 by means of bearings 8, 9, is part of a ball screw transmission. The spindle 10 belonging to this transmission is mounted in the rotor 7 in a rotationally fixed manner and has a central bore in which the transmission plunger 11 is mounted. The ends of the transmission plunger 11 act on the clutch 12 with permanent magnets according to DE 10 2010045617.9 of the applicant (to which reference is made here for disclosure purposes), which forms a clutch 12 with the DK pistons 18. This is a component of the piston-cylinder unit or tandem master cylinder described below.

[0019] The tandem master cylinder 13 is axially connected to the housing 5 and, in a known manner, comprises a cylinder and two pistons 18 and 19 displaceably arranged therein, which form two working chambers. Hydraulic lines lead from the working chambers to an expansion tank 13a, and hydraulic lines 27, 28 lead via a valve system to the wheel brakes (not shown) of the braking system. The hydraulic actuation unit HCU shown in the drawing can be constructed in different ways, depending on the system or application. An example of this is described in DE 10 2007062839, to which reference is made here for disclosure. The components of the pressure control for an electro-hydraulic brake (EHB) (as described, for example, in the Brake Manual, Edition 1, Viehweg Verlag) can also be provided.

[0020] The mode of operation and the resulting additional features and advantages are described below: The brake pedal 1 acts on the piston 4 via the pedal tappet 2, whereby the volume displaced by the piston 4 is transmitted via the hydraulic line to a hydraulic travel simulator 17. Redundant travel sensors S2, S4 are coupled to the movement of the piston 4 via actuating elements 15, 15a. These then act on the sensors through the motor. The travel sensors S2, S4 control the motor 6 via an evaluation unit (ECU) and simultaneously actuate a normally open 2 / 2-way solenoid valve 24. The auxiliary piston is returned to its original position by a return spring 29. All other functions, such as the throttle check valve 23 and the motor in the event of motor failure, are described in DE 10 2010045617.9 (which is hereby incorporated by reference for disclosure).

[0021] The following description therefore focuses on the sensor module.

[0022] In the aforementioned patent application, the sensors are located in the pedal interface. This is connected to the ECU via a wiring harness, which is usually connected to the HCU. This wiring harness is expensive because the sensor wires must be shielded and sealed at the points where they exit the pedal interface and enter the ECU.

[0023] When relocated parallel to the THZ or actuator, all sensors with electrical wires can be combined in a sensor module and connected directly to the ECU via a connector 30. Since the costs for the electrical connection are low, the sensors can be operated with a reduced voltage supply, for example.

[0024] Therefore, a further advantage is that, for example, a third pedal travel sensor S2a can be used. This makes it possible to monitor the two pedal travel sensors S2 and S4 within a specific travel range, or this S2a can also be used as a redundant brake light switch. Furthermore, from this position of the sensor module, both the brake fluid level can be detected by a magnetic flux-sensitive sensor, in particular Hall sensor S5 with magnet S5a in the float of the expansion tank 13a, and the piston position of the brake fluid reservoir can be detected by a magnetic flux-sensitive sensor, in particular Hall sensor S6 and magnet S6a in the brake fluid reservoir piston.

[0025] To ensure that the rotor's angle of rotation is also detected in the sensor module via the rotary encoder S1, the rotor rotation is transmitted via a gear 3 through a shaft 20 to the target 22 (permanent magnet). Within the stator, the shaft is protected in the coil body, just like the Fig. 3 shows. The shaft is supported on both sides in bearings 21 in the actuator housing.

[0026] Also protected in the stator and mounted on both sides of the actuator are the actuating elements 15, 16 for the pedal travel sensors. These preferably act via racks on a gear with a target, so that the two rotation angle Hall sensors S2 and S4 deliver the pedal travel signal. Alternatively, it is conceivable for the actuating elements with a corresponding target to act on various linear Hall sensors, whose signals are converted by an evaluation circuit into a signal proportional to the pedal travel. The sensor module is preferably attached to the THZ, has a tight, stable housing and is pressed onto the flange, e.g. of the motor housing, together with the THZ via a seal (not shown). In the sensor module, return springs 32 act on the actuating elements and flange of the pedal interface. The sensor signals are calibrated via a small free travel at the beginning of braking so that all tolerances, including temperature tolerances, are compensated.The sensor module is connected directly to the ECU via a connector 30, without any intermediate cables. The entire wiring harness for the integrated system has only one main connector 41, which is connected to an on-board power supply control unit and, preferably, a gateway for the bus line.

[0027] At the Fig. 2, the actuator with motor 6 and housing 5, spindle, rotor and THZ is the same as Fig. 1. Differences are the position of preferably two auxiliary cylinders or pistons, which are arranged at least partially in the axial direction in the area of the THZ and, in particular, are combined or integrated with the THZ. This also eliminates the external connecting line from piston 4 to travel simulator 17. These pistons are actuated via rods 35 and 35a, which are connected to the pedal plate 34 and mounted in the housing 5.

[0028] It is also possible to have only one piston, which is connected to the piston and the rods via rigid actuating elements.

[0029] The elastic member 33a with the flange sleeve 33 is embedded in the pedal plate.

[0030] The drawing shows the main dimensions that determine the overall length. These show that the pedal travel accounts for approximately 3.5 times the overall length. The minimum distance between the pedal plate 34 and the housing 5 corresponds to the stroke and thus the main dimension of the pedal interface.

[0031] In the following dimensional chain, the pedal stroke again determines the spindle length in addition to the ball screw (KGT), whose length depends not only on the stroke but also on the piston force. The insertion of the DK piston into housing 5 is also stroke-dependent, as is the remaining THZ. An effective way to shorten the pedal stroke is to increase the pedal transmission ratio.

[0032] The sensor module corresponds to that of the Fig. 1.

[0033] Fig. Figure 2a shows the arrangement of the sensor module 31 parallel to the actuator housing, with the ECU and HCU also located primarily in the actuator area. Here, too, the sensor module is directly connected to the ECU. The latter also has a main connector 41 to the vehicle electrical system. The sensor module contains the sensors S2, S4, and S2a. To integrate the sensors S1, S5, and S6, the sensor module requires corresponding extensions to the brake fluid reservoir 14, the THZ 13, and the gear 3 of the rotary encoder. The sensors S2, S4, and S2a are activated via the rod 35a with the actuating elements 15, 15a. For this purpose, the rod 35a can be designed as a tube.

[0034] This highlights key factors that lead to a compact actuator and simultaneously reduce the costs of the pedal interface and sensor module. Installation is also simple.

[0035] Fig. Figure 3 shows a section through the stator of the electric motor with winding 36, coil formers 37 and 37a, stator tooth 38, rotor 7, and outer casing (outer sheath) 39. According to the prior art, the stator teeth with coils are pressed into the outer sheath. The coil formers are designed in such a way that they accommodate the actuating elements 15 and 6 through recesses. The profile can be round or, as shown at 16, rectangular. The shaft 20 to the gear wheel is provided in the center. Play is provided to prevent jamming. The recess in the coil formers protects the elements in the motor. With additional potting of the coils, the casting mold has the appropriate contour.

[0036] Fig. Figure 4 shows the design of the sensor actuator support. The sensors have very small actuation forces, and reset is achieved via the Fig. 1, which act in the sensor module. Should jamming occur, a predetermined breaking point 40 is provided in the sensor support, which is connected to the pedal interface 33, 34. This breaking point becomes effective when the actuation force exceeds approximately 10 times the spring force.

[0037] Fig. Figures 5 - 5b show possible ECU architectures for the sensors, motor, and valve control. The microcontrollers MC1 and MC2 are standard in all ABS and ESP systems. The microcontrollers are redundantly connected. Errors are detected by comparing various safety-relevant signals, and in the event of a fault, the system is shut down. The output signals control the solenoid valves MV and the pump motor, the latter if the invention is used in a system in which a conventional ABS / ESP is connected in parallel to the electromotive brake booster (BKV). In the present integrated system, in which the EC motor performs both the BKV and the ABS function, an additional MC3 is used, which in turn is monitored by MC1 and MC2. The methods for monitoring and shutting down microcontrollers MC1 and MC2, and MC3 by MC1 and MC2, are known and therefore not described in detail here.

[0038] The MC have a reduced voltage supply U stab1 and U stab2 , which are preferably supplied from terminal 15 of the vehicle electrical system.

[0039] Furthermore, the function and safety-relevant sensors are shown, such as DG (pressure sensor) and S2, S4 and S2a pedal travel sensors.

[0040] The function of the brake signals, traditionally generated by the brake light switch, is extremely safety-critical for many systems such as the engine and transmission control. Therefore, all braking systems today either have a fully redundant brake light switch or the pressure sensor signal is provided via the bus line in conjunction with a non-redundant brake light switch. Installation, along with the wiring harness and the brake light switch, incurs additional costs. This integrated braking system with two pedal travel sensors and an additional pressure sensor eliminates the aforementioned additional effort. There are various options for this:

[0041] Fig. 5. MC1, MC2, and MC3 are connected to a redundant power supply, as are pedal travel sensors S2 and S4. The brake signal is redundantly fed from MC1 and MC3 to the BS output of the on-board power supply control unit. The signal from the pressure sensor DG is fed from MC1 to the bus, e.g., CAN. If MC1 and MC2 fail, MC3 can still operate the brake booster in emergency mode. The phase current measurement via a shunt (not shown) can also serve as a replacement for the pressure sensor.

[0042] The solution presented here for generating the brake signal is significantly safer and at the same time more cost-effective than the conventional method.

[0043] Fig. 5a shows another alternative in which the signal from the pedal travel sensor is fed directly to the BS output, but must still be processed separately for output to the on-board power supply control unit.

[0044] Fig.5b uses an additional pedal travel sensor, preferably a switching signal that does not require separate processing for output at the brake system. This third sensor enables detection of the failure of S2 or S4, so that if one of the S2 or S4 sensors fails, the brake system can be operated in emergency mode. The failure of the brake system is safety-relevant, since switching to the fallback level requires significantly higher pedal forces for a given braking force.

[0045] Some aspects of the invention are presented below. 1. Actuating device for a vehicle brake system, with a first piston-cylinder unit, at least one working chamber of which is to be connected to at least one wheel brake of the vehicle via at least one hydraulic line, further with an electro-mechanical drive device and an actuating device, in particular a brake pedal, characterized in that a sensor device (31) is provided which is arranged at least partially in the region of the piston-cylinder unit (13). 2. Actuating device according to aspect 1, characterized in that the sensor device has a sensor module (31) which comprises at least two sensors (S1, S2, S2a, S4) in one structural unit, in particular on a common printed circuit board. 3. Actuating device according to aspect 1 or 2, characterized in that the sensor device (31) has at least one, in particular two or three pedal stroke sensors (S2, S2a, S4) and / or rotary angle sensors (S1). 4. Actuating device according to one of the preceding aspects, characterized in that at least one (linear or rotary) sensor can be actuated by means of an actuating element (15, 16) running or mounted parallel to the axis of the drive device, in particular through the drive device or its housing. 5. Actuating device according to one of the preceding aspects, characterized in that a spring device (29) is provided for resetting at least one linear sensor actuating element. 6. Actuating device according to one of the preceding aspects, characterized in that the sensor actuating device (31) has an overforce protection, in particular a predetermined breaking point (40) (). 7. Actuating device according to one of the preceding aspects, characterized in that the sensor device has at least one further sensor, in particular a liquid level sensor (S5) and / or piston position sensor (S6). 8. Actuating device according to one of the preceding aspects, characterized in that the sensor device (31) is attached to the piston-cylinder unit (13). 9. Actuating device according to one of the preceding aspects, characterized in that the sensor device (31) is connected to an electronic control unit (ECU), in particular is directly contacted. 10. Actuating device according to one of the preceding aspects, characterized in that a redundant power supply is provided for the sensors. 11. Actuating device for a vehicle brake system, with a first piston-cylinder unit, at least one working chamber of which can be connected to at least one wheel brake of the vehicle via at least one hydraulic line, further with an electro-mechanical drive device and an actuating device, such as a brake pedal, in particular according to one of the preceding aspects, characterized in that the actuating device has at least one further piston-cylinder unit (4) which acts on a hydraulic travel simulator (17), which is arranged at least partially in the region of the first piston-cylinder unit (13), whose piston (4) can be actuated by means of the actuating device (1, 2) and which is connected to a piston of the first piston-cylinder unit (13) via a connecting device. 12. Actuating device according to aspect 11, characterized in that the force of the actuating device, in particular the pedal force, is transmitted to at least one of the further piston-cylinder units (4) by means of a tappet or rod (35a). 13. Actuating device according to aspect 12, characterized in that the plunger(s) (35a) extend parallel to the axis of the drive device, in particular through the drive device, preferably through the coil body of the winding of the electric motor. 14. Actuating device according to one of aspects 11 to 13, characterized in that a pedal plate (34) is provided for transmitting the force of the actuating device, in particular the pedal force. 15. Actuating device according to aspect 14, characterized in that an elastic device (33, 33a), via which the pedal travel sensor is actuated, is attached to the pedal plate (34) or integrated therein. 16. Actuating device according to one of aspects 11 to 15, characterized in that the further piston-cylinder unit (4) is combined, in particular integrated, with the first piston-cylinder unit (13). 17. Actuating device according to one of aspects 11 to 16, characterized in that a spring device, in particular a central return spring, is provided for resetting the piston(s) of the further piston-cylinder unit(s). 18. Actuating device according to one of the preceding aspects, characterized in that a separate brake light switch is avoided by means of a suitable sensor or motor control. 19. Actuating device according to aspect 18, characterized in that a separate brake light switch is replaced by the use of redundant pedal travel sensors and redundant power supply. 20. Actuating device according to aspect 18, characterized in that a separate brake light switch is replaced by the use of a third pedal travel sensor, preferably a Hall switch. 21. Actuating device according to aspect 20, characterized in that the third sensor is used to monitor the other two pedal travel sensors. 22. Actuating device, in particular according to one of the preceding aspects, characterized in that the ECU outputs to the vehicle electrical system control units a pressure or motor current proportional signal predominantly via the phase current line and a pedal position proportional signal by a redundant voltage supply via a separate line. 23. Actuating device, in particular according to one of the preceding claims, characterized in that a separate brake light switch is replaced by the use of a third microcontroller (MC) for motor control and generation of the brake signal. 24. Actuating device, in particular according to one of the preceding claims, characterized in that redundant pedal travel sensors and a pressure sensor are used to generate brake signals. 25. Sensor module, in particular for use in an actuating device according to one of the preceding aspects, characterized in that at least two pedal travel sensors (S2, S2a, S4) and a rotary angle sensor (S1) are combined to form a structural unit, in particular on a printed circuit board. 26. Sensor module according to aspect 25, characterized in that the structural unit has at least one further sensor, such as a liquid level sensor (S5), piston position sensor (S6) and / or pedal travel sensor (S2a). 27. Sensor module according to aspect 18 or 19, characterized in that a direct contact to the ECU, in particular a plug connection (30), is provided. List of reference symbols 1 brake pedal 2 pedal tappets 3 Gear for angle sensor 4 auxiliary pistons 4a Auxiliary piston cylinder 5 housings 6 Electric motor 7 Rotor 8 warehouses 9 camps 10 spindle 11 transmission tappet 12 Clutch 13 tandem master cylinders (THZ) 13a Expansion tank 14 Expansion tank 15 Actuating element 15a Actuating element 16 Actuating element 17 hydraulic travel simulator 18 SD pistons 19 SK pistons 20 wave 21 camps 22 Target 23 Throttle check valve 24 2 / 2-way solenoid valve (MV) 25 Magnet in the float 26 Magnet in the SK piston 27 Hydraulic line 28 Hydraulic line 29 Return spring 30 sensor connectors 31 Sensor module 32 return springs 33 Flange sleeve 33a elastic member 34 Pedal plate 35 Bar 1 35a Pole 2 36 windings 37 coil bodies 37a Coil body 38 Stator tooth (yoke tooth) 39 Outer casing (outer jacket) 40 predetermined breaking point 41 main plug MC1 Microcontroller MC for ABS / ESP MC2 ditto redundant MC3 ditto. for engine control Ustab1 / 2 voltage stabilization DG pressure sensor BS output circuit brake signal to on-board power supply control unit S1 angle sensor S2 pedal travel sensor S4 pedal travel sensor S2a pedal travel sensor S5 Brake fluid level sensor (magnetic flux sensitive sensor, like Hall sensor) S6 Piston position sensor (magnetic flux sensitive sensor, like Hall sensor)

Claims

[1] Actuating device for a vehicle braking system, comprising: - a first piston-cylinder unit, at least one working chamber of which is to be connected or is connected to at least one wheel brake of the vehicle via at least one hydraulic line, - an electro-mechanical drive device and an actuating device, in particular a brake pedal, - an expansion tank which is hydraulically connected to the at least one working chamber, characterized by that a sensor device (31) is provided, wherein the sensor device (31) comprises at least one liquid level sensor (S5) in the form of a magnetic flux-sensitive sensor (S5, S5a) which detects at least one magnet (S5a) in a float of the compensation tank (13a), and wherein the magnetic flux-sensitive sensor comprises a Hall sensor (S5) for detecting the magnet (S5a) in the float. [2] Actuating device according to claim 1, characterized bythat the sensor device (31) is arranged at least partially in the region of the piston-cylinder unit (13). [3] Actuating device according to claim 1 or 2, characterized by that the sensor device (31) has a sensor module (31) which comprises at least two sensors (S1, S2, S2a, S4) in one structural unit, in particular on a common printed circuit board. [4] Actuating device according to one of the preceding claims, characterized by that the sensor device (31) has at least one, in particular two or three pedal stroke sensors (S2, S2a, S4) and / or rotary angle sensors (S1). [5] Actuating device according to one of the preceding claims, characterized by that the sensor device (31) has at least one further sensor, in particular a piston position sensor (S6). [6] Actuating device according to one of the preceding claims, characterized bythat the sensor device (31) is attached to the piston-cylinder unit (13). [7] Actuating device according to one of the preceding claims, characterized by that the sensor device (31) is connected to an electronic control unit (ECU), in particular directly contacted. [8] Actuating device according to one of the preceding claims, characterized by that a redundant power supply is provided for the sensors. [9] Actuating device according to one of the preceding claims, characterized by that the sensor device (31) is arranged parallel to the actuator housing and / or parallel to the piston (18) of the piston-cylinder unit (13). [10] Actuating device according to one of the preceding claims, characterized bythat the sensor device (31) has an extension to the brake fluid reservoir (14), wherein the extension is aligned in particular orthogonal to the piston-cylinder unit (13). [11] Actuating device according to claim 10, characterized by that the Hall sensor (S5) is arranged on the extension to the brake fluid reservoir (14). [12] Vehicle braking system with an actuating device according to one of the preceding claims. [13] Vehicle with a vehicle braking system according to claim 12.

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