Abstract
The invention relates to an 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, and also with an electromechanical drive device and an actuating device, in particular a brake pedal. According to the invention, a sensor device (31) is provided, which is arranged at least partially in the area of the piston-cylinder unit (13).
Claims
[1] An actuating device for a vehicle brake system, comprising a first piston-cylinder unit, at least one working chamber of which is to be connected via at least one hydraulic line to at least one wheel brake of the vehicle, further comprising an electromechanical 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 claim 1, characterized in that the sensor device has a sensor module (31) which comprises at least two sensors (S1, S2, S2a, S4) in a single unit, in particular on a common printed circuit board.
[3] An actuating device according to claim 1 or 2, characterized in that the sensor device (31) has at least one, in particular two or three pedal-travel sensors (S2, S2a, S4) and/or angle-of-rotation sensors (S1).
[4] Actuating device according to one of the preceding claims, 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 the housing of the latter.
[5] Actuating device according to one of the preceding claims, 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 claims, characterized in that the sensor-actuating device (31) has an overload protection, in particular a rated break point (40) ().
[7] Actuating device according to one of the preceding claims, characterized in that the sensor device has at least one further sensor, in particular a liquid level sensor (S5) and/or a piston position sensor (S6).
[8] Actuating device according to one of the preceding claims, characterized in that the sensor device (31) is fitted to the piston-cylinder unit (13).
[9] Actuating device according to one of the preceding claims, 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 claims, characterized in that a redundant voltage supply is provided for the sensors.
[11] Actuating device for a vehicle brake system, with a first piston-cylinder unit, at least one working space of which is to be connected via at least one hydraulic line to at least one wheel brake of the vehicle, further comprising an electromechanical drive device and an actuating device, such as a brake pedal, in particular according to one of the preceding claims, characterized in that the actuating device has at least one further piston-cylinder unit (4) which acts on a hydraulic path simulator (17), which is arranged at least partially in the region of the first piston-cylinder unit (13), the piston (4) of which 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 claim 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 claim 12, characterized in that the tappet(s) (35a) run 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 claims 11 to 13, characterized in that a pedal plate (34) is provided to transmit the force of the actuating device, in particular the pedal force.
[15] Actuating device according to claim 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 is integrated into the latter.
[16] Actuating device according to one of the claims 11 to 15, characterized in that the further piston-cylinder unit (4) is combined with, in particular integrated in, the first piston-cylinder unit (13).
[17] An actuating device according to one of the claims 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 claims, characterized in that a separate brake light switch is avoided by means of a suitable sensor system and/or motor control.
[19] Actuating device according to claim 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 claim 18, characterized in that a separate brake light switch is replaced by using a third pedal travel sensor, preferably a Hall switch.
[21] Actuating device according to claim 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 claims, characterized in that the ECU outputs a signal which is proportional to pressure or engine current predominantly via the phase current line and outputs a signal which is proportional to pedal position by means of a redundant voltage supply via a separate line to the on-board power supply control units.
[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 braking 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 claims, characterized in that at least two pedal travel sensors (S2, S2a, S4) and a rotational angle sensor (S1) are combined into a single unit, in particular on a printed circuit board.
[26] Sensor module according to claim 25, characterized in that the 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 claim 18 or 19, characterized in that a direct connection to the ECU, in particular a plug-in connection (30), is provided.
Description
[0001] The invention relates to an actuating device for a vehicle brake system.
State of the art
[0002] The trend in future braking force and control systems is towards the integration of all functions into a single unit. The focus is on:
• reliability
• costs and weight
• functionality ABS/ESP and for all assistance functions
• size and length
[0003] An important component that determines size and cost is the sensors. The systems mentioned above generally require at least sensors for pedal travel, engine angle, pressure, brake fluid level and possibly also piston position. The signals from these sensors must be supplied to an electronic control unit (ECU). A connection with a cable set and plug is complex and reduces reliability. The size is essentially determined by the pedal interface, actuator and tandem main cylinder (THZ).
[0004] Travel simulators are often used in the pedal interface, as described in DE 10 2008 063 771 of the applicant or auxiliary pistons as described in DE 10 2010 045 617.9 of the applicant (reference is hereby made to these documents), which have a significant influence on the overall length. In addition, the pedal stroke, with a factor of 3.5, strongly determines the overall length. The sensors, preferably combined into a module (DE 10 2010 045 617.9), also determine the size if they are housed in the pedal interface.
[0005] Future vehicle concepts require short dimensions in both the footwell (pedal interface) and the aggregate or engine compartment (actuator + THZ).
Aim of the invention
[0006] The invention is based on the task of reducing the costs for sensors and electrical connection and optimizing the overall length of the integrated unit.
Solution of the problem
[0007] The solution of this problem is achieved by the provision of a sensor device which is arranged at least partially in the area of the piston-cylinder unit. 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 the structural conditions, also in terms of costs.
[0008] Advantageous embodiments or configurations of the invention arise from the further claims, to which reference is made here.
[0009] The costs for the sensors, based on the summary of the sensors on a printed circuit board in DE 10 2010 045 617.9 for angle of rotation and pedal travel sensors, can be reduced by extending it to further and ultimately all sensors that are required for the braking system. These are 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 with the ESP pressure signal, since the ‘braking’ signal is needed by many engine, transmission and assistance function systems in a fail-safe manner.
[0010] Today, these sensors have a separate wiring harness to the corresponding ECU. It is advantageous to replace all wiring harnesses with a direct connection from the sensor module to the ECU via a plug connection. The ECU itself then only has a wiring harness to the power supply and to the on-board electrical system control unit. This also makes assembly easier.
[0011] A reduction in the length of the integrated unit is achieved according to advantageous embodiments of the invention by:
1. moving the sensor module from the pedal interface to the TCM or actuator with corresponding actuating elements by the motor.
2. removal of all components such as stepped pistons and travel simulators from the pedal interface. Thus, the distance from the actuator to the pedal plate is now only equal to the pedal stroke.
3. reduction of the pedal stroke by increasing the pedal ratio.
[0012] Examples of the invention and its embodiments are shown in the drawings and described in more detail below.
Description of the Figures
[0013] The following show:
[0014] Fig. 1 a structure of the actuating device from DE 10 2010 045 617.9 with relocation of the sensor module to the THZ, with direct electrical connection to the ECU;
[0015] Fig. 2 an interface with an optimized length with the auxiliary piston being relocated to the THZ, also with the sensor module relocated;
[0016] Fig. 2a the arrangement of the sensor module of the HCU and ECU parallel to the actuator;
[0017] Fig. 3 a cross-section of the stator with the position of the sensor shaft and actuating elements;
[0018] Fig. 4 a section of the force transmission from the pedal to the actuating element with over-force protection; and
[0019] Fig. 5–Fig. 5a various circuits with integration of the brake light switch.
[0020] The actuating device for a motor vehicle brake shown in Fig. 1 has a brake pedal 1 with a pedal tappet 2. The pedal tappet 2 acts via a prestressed elastic member 33a and flanged sleeve 33 on 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 that is guided in a sealed manner in a partition wall of the cylinder. This central extension acts on a transmission tappet 11, which is firmly connected to a piston 18 of a piston-cylinder unit 13 via a coupling, in particular a magnetic coupling 12, but can be disconnected via the coupling.
[0021] A housing 5 of a power actuator for the brake booster (BB) and preferably the pressure modulation for ABS, ESP and the like is connected axially to the cylinder 4a. As in the example described here, this can, for example, have an electric motor with a stator 6 and a rotor 7, which are 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 drive. The spindle 10 belonging to this drive is mounted in the rotor 7 in a rotationally fixed manner and has a central bore in which the transmission tappet 11 is mounted. The ends of the transmission tappet 11 act on the clutch 12 with permanent magnets according to the DE 10 2010 045 617.9 of the applicant (which is referred to here for disclosure purposes), which forms a clutch 12 with the DK pistons 18. This forms part of the piston-cylinder unit or tandem master cylinder described below.
[0022] The tandem master cylinder 13 is attached to the housing 5 in an axially adjacent manner and, in a known manner, has a cylinder and two pistons 18 and 19 that are arranged in a displaceable manner therein and 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 (not shown) wheel brakes of the braking system. The hydraulic control unit HCU shown in the drawing can be constructed differently, according to different system or application cases. An example of this is described in DE 10 2007 062 839, to which reference is made here for the disclosure. It may also include the components of the pressure control for an electro-hydraulic brake (EHB) (as described, for example, in the brake manual, edition 1, Viehweg Verlag).
[0023] The mode of operation and the resulting further features and advantages are described below:
The brake pedal 1 acts on the piston 4 via the pedal tappet 2, with the volume displaced by the piston passing to a hydraulic travel simulator 17 via the hydraulic line. The movement of the piston 4 couples redundant travel sensors S2, S4 via actuating elements 15, 15a. These then act on the sensors through the motor. The displacement sensors S2, S4 control the motor 6 via an evaluation unit (ECU) and at the same time operate a currentless open 2/2-way solenoid valve 24. The auxiliary piston is returned to the initial position by a return spring 29. All other functions, such as the throttle check valve 23 and motor in the event of motor failure, are described in DE 10 2010 045 617.9 (which is hereby referred to for disclosure in this regard).
[0024] The following description is therefore focused on the sensor module.
[0025] In the above-mentioned patent application, the sensors are arranged in the pedal interface. This is connected via a wiring harness to the ECU, which is usually connected to the HCU. This wiring harness is expensive because the sensor lines must be shielded and also sealed when they exit the pedal interface and enter the ECU.
[0026] If the sensors are relocated parallel to the TDC or actuator, all sensors can be combined with electrical lines in a sensor module and connected directly to the ECU via a 30-pin connector. Since the costs for the electrical connection are low, the sensors can be operated with a reduced power supply, for example.
[0027] A further advantage is that a third pedal travel sensor S2a can be used. This makes it possible to monitor the two pedal travel sensors S2 and S4 in a certain travel range, or this S2a can also be used as a redundant brake light switch. In addition, the level of the brake fluid can be detected by a magnetic flux-sensitive sensor, in particular a Hall sensor S5 with magnet S5a in the float of the equalizing reservoir 13a, and the piston position of the SK piston can be detected by a magnetic flux-sensitive sensor, in particular a Hall sensor S6 and magnet S6a in the SK piston.
[0028] In order for the angle of rotation of the rotor to also be detected in the sensor module via the angle of rotation sensor S1, the rotor rotation is transmitted via a gear wheel 3 via a shaft 20 to the target 22 (permanent magnet). Inside the stator, the shaft is protected in the coil body, as shown in Fig. 3. The shaft is supported in bearings 21 on both sides in the actuator housing.
[0029] The actuating elements 15, 16 for the pedal travel sensors are also protected in the stator and supported on both sides in the actuator. These preferably act via racks on a gear wheel with a target, so that the two angle-of-rotation Hall sensors S2 and S4 provide the pedal travel signal. Alternatively, it is conceivable that the actuating elements with a corresponding target act on different linear Hall sensors, the signals of which 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 sealed, stable housing and is pressed together with the THZ on the flange, e.g. of the engine housing, via an un-drawn seal on the front side. 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 are also compensated by temperature. The sensor module is directly connected to the ECU with a plug 30 without intermediate lines. The entire line set for the integrated system has only one main plug 41, which is connected to an on-board power supply control unit and preferably to a gateway for the bus line.
[0030] In the design shown in Fig. 2, the actuator with motor 6 and housing 5, spindle, rotor and THZ is the same as in Fig. 1. The differences are the location 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 the displacement 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.
[0031] It is also possible to have only one piston, which is connected to the piston and the rods via flexurally stiff actuating elements.
[0032] The elastic element 33a with the flanged sleeve 33 is embedded in the pedal plate.
[0033] The main dimensions that determine the overall length are shown in the drawing. These show that the pedal travel is approx. 3.5 times the length. The minimum distance of the pedal plate 34 to the housing 5 corresponds to the stroke and thus to the main dimension of the pedal interface.
[0034] In the following chain of dimensions, the pedal stroke again determines the spindle length next to the ball screw, whose length, in addition to the stroke, depends on the piston force. The immersion of the DK piston in the housing 5 is dependent on the stroke, as is the remaining THZ. An effective way of shortening the pedal stroke is to increase the pedal ratio.
[0035] The sensor module corresponds to that of Fig. 1.
[0036] Fig. 2a shows the arrangement of the sensor module 31 parallel to the actuator housing, in which the ECU and HCU are also located predominantly in the area of the actuator. Here, too, the sensor module is directly connected to the ECU. The latter also has a main connector 41 to the on-board electrical system. The sensor module contains the sensors S2, S4 and S2a. To integrate the sensors S1, S5 and S6, the sensor module requires appropriate extensions to the brake fluid reservoir 14, the THZ 13 and the gear wheel 3 of the angle of rotation sensor. The sensors S2, S4 and S2a are activated by the rod 35a with the actuating elements 15, 15a. For this purpose, the rod 35a can be designed as a tube.
[0037] This shows the essential facts that lead to a compact actuator and at the same time reduce the costs for the pedal interface and sensor module. Assembly is also simple.
[0038] Fig. 3 shows a cross-section of 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 to receive the actuating elements 15 and 6 through recesses. The profile can be round or, as shown at 16, also rectangular. The shaft 20 to the gear wheel is provided in the center. Play is provided to prevent jamming. The elements in the motor are protected by the recess in the coil formers. If the coils are also to be encapsulated, the mold has the corresponding contour.
[0039] Fig. 4 shows the design of the sensor actuating element support. The sensors have very small actuating forces, and the return is provided by the return springs shown in Fig. 1, which act in the sensor module. Should a jam occur, a break point 40 is provided in the sensor support, which is connected to the pedal interface 33, 34, and this becomes effective when the actuating force exceeds approximately 10 times the spring force.
[0040] Fig. 5–Fig. 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 connected redundantly. By comparing various safety-related signals, faults are detected and the system is switched off in the event of a fault. 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 with 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 of monitoring and shutting down microcontrollers MC1 and MC2, MC3 of MC1 and MC2 are known and are therefore not described in detail here.
[0041] The MCs have a reduced voltage supply and Ustab2, which are preferably supplied from terminal 15 of the on-board power supply.
[0042] Furthermore, the function- and safety-relevant sensors are shown, such as DG (pressure sensor) and S2, S4 and S2a pedal travel sensors.
[0043] The function of the brake signals, conventionally generated by the brake light switch, is extremely safety-critical for many systems such as engine and transmission control. Therefore, in all brake systems today, either a fully redundant brake light switch or the signal of the pressure transducer in connection with a non-redundant brake light switch is provided. Installation, together with the wiring harness and the brake light switch, incurs additional costs. The integrated braking system with two pedal travel sensors and an additional pressure sensor eliminates the above-mentioned additional costs. There are various possibilities for this:
Fig. 5. MC1, MC2 and MC3 are connected to a redundant power supply, as are the pedal travel sensors S2 and S4. The redundant brake signal is supplied from MC1 and MC3 to the output BS of the on-board power supply control unit. The signal from the pressure generator DG is supplied from MC1 to the bus, e.g. CAN. If MC1 and MC2 fail, MC3 can still operate the BKV in emergency mode. The phase current measurement via a shunt (not shown) can also be used as a substitute for the pressure transducer.
[0044] The solution presented here for generating the brake signal is significantly safer and at the same time more cost-effective than the conventional method.
[0045] Fig. 5a shows a further alternative in which the signal of the pedal travel sensor is directly routed to the BS output, but it still has to be processed separately for output to the on-board power supply control unit.
[0046] Fig. 5b uses an additional pedal travel sensor, preferably a switching signal, which does not have to be processed separately for output at BS. This third sensor makes it possible to detect the failure of S2 or S4, so that the BKV can be operated in emergency mode if S2 or S4 fails. The failure of the BKV is relevant to safety, since considerably higher pedal forces are required for a certain braking action when switching to the fallback level.
List of reference designations
1 Brake pedal
2 Pedal tappet
3 Gear wheel for angle of rotation sensor
4 Auxiliary piston
4a Auxiliary piston cylinder
5 Casing
6 Electric motor
7 Rotor
8 Bearing
9 Bearing
10 Spindle
11 Transfer tappet
12 Clutch
13 Tandem master cylinder (THZ)
13a Compensation reservoir
14 Compensation reservoir
15 Actuating element
15a Actuating element
16 Actuating element
17 Hydraulic path simulator
18 SD piston
19 SK piston
20 Shaft
21 Bearing
22 Target
23 One-way flow control valve
24 2/2-way solenoid valve (MV)
25 Magnet in float
26 Magnet in SK piston
27 Hydraulic line
28 Hydraulic line
29 Return spring
30 Sensor connector
31 Sensor module
32 Return springs
33 Flanged sleeve
33a Flexible element
34 Pedal plate
35 Rod 1
35a Rod 2
36 Winding
37 Bobbin
37a Bobbin
38 Stator tooth (yoke tooth)
39 Outer casing (outer sheath)
40 Predetermined breaking point
41 Main connector
MC1 Microcontroller MC for ABS/ESP
MC2 ditto, redundant
MC3 ditto, for engine control
Ustab1/2 Voltage stabilization
DG Pressure transducer
BS Output circuit, brake signal to the on-board power supply control unit
S1 Rotational angle sensor
S2 Pedal travel sensor
S4 Pedal travel sensor
S2a Pedal travel sensor
S5 Brake fluid level sensor (magnetic flux-sensitive sensor, like a Hall sensor)
S6 Piston position sensor (magnetic flux-sensitive sensor, like a Hall sensor)
CITATIONS INCLUDED IN THE DESCRIPTION
[0047] This list of documents cited by the applicant has been generated automatically and is included solely for the convenience of the reader. The list is not part of the German patent or utility model application. The DPMA does not assume any liability for possible errors or omissions.
Cited patent literature
[0048]
DE 102008063771 [0004]
DE 102010045617 [0004, 0004, 0009, 0014, 0021, 0023]
DE 102007062839 [0022]
Cited non-patent literature
[0049]
Brake manual, edition 1, Viehweg Verlag [0022]
