Sensor device for a brake system, actuator device for a brake system, and brake system for a motor vehicle

Abstract

The invention relates to a sensor device for a brake system (10) of a motor vehicle, comprising: a vibration sensor (52) which is designed to be fastened to a brake component (42, 46) of the brake system (10) and to detect body vibrations of the brake component (42, 46); and an evaluation unit (54) which is in signal connection with the vibration sensor (52) and is designed to estimate, from a sensor signal of the vibration sensor (52), a clamping force between at least one body-side brake component (44) of the brake system (10) and a wheel-side brake component (42) which interacts with the body-side brake component (44) during braking. The invention further relates to an actuator device for a brake system (10) and to a brake system for a motor vehicle.

Description

Technical Field

[0001] The present invention relates to a sensor device for a braking system, an actuator device for a braking system, and a braking system for a motor vehicle. Background Technology

[0002] A braking system typically includes a braking device and an operating unit that operates the braking device. The braking device can be a drum brake or a disc brake. A drum brake typically includes a brake drum and movable brake pads that can be pressed against the brake drum by the operating unit to induce a braking process due to friction. A disc brake typically includes a brake disc and movable brake pads that can be pressed against the brake disc by the operating unit to induce a braking process due to friction. The operating unit can be conventionally constructed with a mechanical connection to a brake pedal that can be operated by the driver, such that each operation of the brake pedal is directly and mechanically transmitted to the brake pads, causing the brake pads to press against the brake drum or brake disc. Alternatively, the operating unit is constructed as an actuator device and forms part of a so-called brake-by-wire system. Here, there is no mechanical connection between the brake pedal and the braking device, where operation of the brake pedal is detected by sensors and the motor of the actuator device is controlled based on sensor signals and other required parameters. The parameters required to operate the electric motor, namely the clamping force, are typically provided by a force sensor. The clamping force between the brake pads and the brake drum or brake disc, i.e., between the vehicle-side and wheel-side braking components of the braking system, is determined from the sensor signal of the force sensor. By determining and taking the clamping force into account when operating the electric motor of the actuator device, it is possible to reliably provide adjustment of the desired clamping force and thus provide the braking effect desired by the driver.

[0003] The disadvantage of this type of force sensor is that it is very expensive because its manufacture can be particularly costly. The force sensor must be placed in the force transmission path, i.e., within the braking device or braking system, where the structural space is very limited and thus complicates the structure of the braking system. Summary of the Invention

[0004] Therefore, the objective of this invention is to provide a sensor device for a braking system that can be constructed simply and at low cost. Furthermore, the structure of a braking system including the sensor device should be simplified.

[0005] The sensor device includes a vibration sensor configured to be mounted on or in such a manner as to a braking component of the braking system, such that vibrations of the braking component, i.e., body vibrations, are detected. The sensor signal from the vibration sensor thus indicates the body vibrations of the braking component in all driving states of the vehicle or in all operating states of the braking system. The vibration sensor is preferably configured as a load measuring unit. In particular, the vibration sensor is a piezoelectric sensor. Alternatively, the vibration sensor can be configured as an acceleration sensor.

[0006] The sensor device also includes an evaluation unit connected to the vibration sensor signal. The evaluation unit is used to evaluate the sensor signal from the vibration sensor. Specifically, the evaluation unit is used to determine the clamping force between at least one body-side braking component and one vehicle-side braking component of the braking system.

[0007] When determining the clamping force from the sensor signal of the vibration sensor, the vibration characteristics of the braking component that vary depending on the clamping or load of the braking component are utilized. Here, the body vibration with a specific vibration amplitude and frequency caused by the clamping of the braking component can be determined, and the clamping force can be inferred based on this. In particular, the spectral changes or frequency shifts that occur according to the clamping of the braking component, especially the shifts in the resonant frequency, are considered. The clamping force can be estimated based on the determined spectral changes caused by a specific clamping or load.

[0008] Therefore, the clamping force between the two braking components and thus the braking force can be indirectly determined by detecting the vibration of the braking component carrying the vibration sensor, where the vibration sensor is not arranged in the force path of the braking system. In particular, the vibration sensor can be arranged at almost any position on the braking component, because there is more or less body vibration at each position of the braking component.

[0009] Preferably, the evaluation unit is configured to estimate the change in the clamping force of the braking device from the change in the sensor signal of the vibration sensor. In particular, the evaluation unit is configured to determine the moment when the vehicle-side braking component abuts against the wheel-side braking component, either from the determined clamping force or from the change in the clamping force. In other words, the abutment of the vehicle-side braking component against the wheel-side braking component can be determined by a predetermined change in the spectrum of the sensor signal of the vibration sensor, where the current change in the spectrum indicates the moment when the clamping force is 0N. The clamping force then increases. The actuator device of the braking system can be continuously operated based on the sensor signal of the vibration sensor, wherein the instantaneous clamping force is continuously estimated from the sensor signal of the vibration sensor. Alternatively, the drive unit can be operated based on the sensor signal of the vibration sensor for a first time period and subsequently based on other parameters, such as the motor parameters of the actuator device, the first time period continuing until the braking components abut against each other, i.e., continuing until a predetermined vibration characteristic for abutment is present and a 0 Newton point is defined. By determining the abutment between the braking components based on the sensor signal of the vibration sensor, the drive device can be operated independently of the wear of the braking components. On the other hand, the wear of braking components can be estimated and defects in the braking system can be detected based on the sensor signals from the vibration sensor.

[0010] In a preferred design, the evaluation unit is configured to actively determine the body vibration of the braking component based on the sensor signal from the vibration sensor, such that the vibration sensor and / or the braking component are pre-definedly excited. This is exemplified by vibrating the vibration sensor and / or the braking component housing the vibration sensor via an actuator, resulting in a pre-defined body vibration of the vibration sensor or the braking component. The change in vibration is determined based on the initial body vibration caused by the vibration excitation, and the clamping force or change in clamping force is determined accordingly. This allows filtering out body vibrations of the vibration sensor and / or the braking component that exist during the operation of the vehicle and are irrelevant to the determination of the clamping force, or even interfere with the determination of the clamping force. Alternatively, the evaluation unit is configured to passively determine the body vibration of the braking component based on the sensor signal from the vibration sensor, that is, without pre-defined vibration excitation of the braking component housing the vibration sensor and / or the vibration sensor.

[0011] Furthermore, the task is accomplished by an actuator device for a braking system, the actuator device having a drive unit configured for operating the braking device and a sensor device according to any one of claims 1 to 4. The drive unit is, in particular, an electromechanical drive unit. Preferably, the electromechanical drive unit has an electric motor and a conversion transmission device, wherein the rotational motion of the electric motor is converted into translational motion by the conversion transmission device. The translational motion is used to displace one of the braking components. The conversion transmission device is, for example, a screw drive.

[0012] Furthermore, the task is accomplished by a braking system for a motor vehicle, the braking system having a braking device and an actuator device according to claim 5. Additionally, the braking system includes a pedal device having a movable pedal element (i.e., a pivotable or translationally displaceable pedal element) and a pedal sensor for determining the pedal travel performed by the pedal element when the pedal element is actuated and / or the pedal force applied to the pedal element when the pedal element is actuated. Furthermore, the pedal device may have a pedal reset unit that causes the pedal to reset when the pedal element is actuated, thereby generating a driver's operating feel.

[0013] During braking system operation, pedal operation is detected by pedal sensors. The drive unit is manipulated based on sensor signals from the pedal sensors, vibration sensors, and, where necessary, other parameters. By manipulating the drive unit, one braking component is moved toward the other, whereby once the gap between the two braking components is overcome, they come into contact and clamp together.

[0014] The braking system is preferably a drum brake or a disc brake. A drum brake includes a brake drum and a movable brake pad, which is operatively connected to a drive unit such that the brake pad, pre-tensioned to a non-contact position, shifts towards the friction surface of the brake drum when the drive unit is operated and presses against the friction surface more or less depending on the operation of the drive unit. A vibration sensor is typically arranged or fixed to the brake drum. A disc brake includes a brake disc and a movable brake pad, which is operatively connected to a drive unit. Also as in a drum brake, the brake pad shifts and presses against the friction surface of the brake disc when the drive unit is operated. The brake pad is operatively supported on a brake caliper. A vibration sensor is arranged or fixed to the brake caliper.

[0015] Preferably, the vibration sensor is positioned outside the direct force flow, particularly on the outer side of the vehicle-side braking components, i.e., the brake caliper or brake drum facing the external environment. This allows the vibration sensor to be easily positioned or fixed to the braking device. In particular, the vibration sensor can be positioned outside the force path of the braking system, where the clamping force is indirectly determined based on the sensor signal from the vibration sensor. Alternatively, the vibration sensor can also be positioned within the force path. Attached Figure Description

[0016] The invention will now be described in detail with reference to the accompanying drawings. The accompanying drawings are as follows:

[0017] Figure 1 A first embodiment of the braking system is illustrated in the schematic diagram;

[0018] Figure 2 A second embodiment of the braking system is illustrated in the schematic diagram;

[0019] Figure 3 Show Figure 1 or Figure 2 The spectrum of the sensor signal from the vibration sensor of the braking system's sensor device. Detailed Implementation

[0020] Figure 1 The braking system 10 of the vehicle is shown. The braking system 10 is configured as a brake-by-wire system and includes a pedal device 20, an actuator device 30, a braking device 40, and a sensor device 50. This brake-by-wire system is characterized in particular by the absence of a mechanical connection between the pedal device 20 and the braking device 40, wherein operation of the braking device is detected and, based on this, the braking device 40 is operated via the actuator device 30.

[0021] The pedal assembly 20 includes a brake pedal 22, which is disposed within the vehicle's interior space and pivotally supported on a support structure of the vehicle. Alternatively, the brake pedal 22 may also be supported on the support structure in a translationally displaceable manner. The brake pedal 22 is connected to a reset unit 24, which is fixed to the support structure and configured to generate a reaction force or reset force when the brake pedal 22 is applied and displaced by an operator. Typically, the reset unit 24 has at least one spring element that generates a reset force or reaction force, wherein the spring characteristic curve is selected to transmit a braking feel to the driver.

[0022] The pedal device 20 also includes a brake pedal sensor 26, which is signal-connected to the control unit 60. The brake pedal sensor 26 detects the pedal travel of the brake pedal 22, which is the travel of the brake pedal 22 when it is operated or loaded by a driver or other person.

[0023] The actuator device 30 is configured as an electric drive and therefore includes a drive unit 31 with an electric motor 32 and a motion conversion unit 34. The electric motor 32 has a stator and a rotor, wherein the stator is electrically connected to the control unit 60 and the rotor is non-rotatably connected to the motion conversion unit 34. The motion conversion unit 34 is configured, for example, as a screw drive and is used to convert the rotational motion of the rotor into translational motion. For example, a nut is driven by the rotor, i.e., rotates, wherein a screw that is translationally supported and acts in conjunction with the nut performs translational motion based on the rotational motion of the nut.

[0024] The braking device 40 is configured as a disc brake 401 and includes a wheel-side braking component 42 (currently a brake disc 421), two body-side braking components 44 (currently two brake pads 441), and another braking component 46 (currently a brake caliper 461) serving as a carrier for the braking device 40. The brake caliper 461 is fixed to the vehicle's support structure. The brake pads 441 are translatably supported on the brake caliper 461. Furthermore, the brake pads 441 are operatively connected to the actuator device 30, i.e., to the motion conversion unit 34 on the output side, so that the brake pads 441 can be translatably displaced when the electric motor 32 is operated. In the inactive state of the electric motor 32, i.e., when there is no operation of the electric motor 32, the brake pads 441 are spaced apart from the brake disc 421 due to spring preload caused by a spring element, such that a gap s exists between the brake pads 441 and the brake disc 421, i.e., between the friction surfaces of the brake pads 441 and the brake disc 421. The wheel-side braking component 42, namely the brake disc 421, is connected to the wheel hub or wheel frame in a manner that prevents relative rotation.

[0025] Sensor device 50 includes a vibration sensor 52, which is fixed to the brake caliper 461 and configured to detect body vibrations of the brake caliper 461. Furthermore, sensor device 50 includes an evaluation unit 54, which processes the sensor signal from vibration sensor 52 as needed, and in particular performs an evaluation, so that the sensor signal can be used to operate braking system 10. Currently, evaluation unit 54 is a component of control unit 60, wherein evaluation unit 54 may also be configured as a stand-alone unit and / or integrated into vibration sensor 52.

[0026] When the vehicle is in motion, the driver's operation of the brake pedal 22, i.e., the driver's request, is detected by the brake pedal sensor 26, and the sensor signal of the brake pedal sensor 26 is transmitted to the control unit 60. In particular, the electric motor 32 is operated based on the sensor signal of the brake pedal sensor 26, thereby displacing and loading the brake pads 441 toward the brake disc 421. Once the brake pads 441 are against the brake disc 421, friction is generated between the brake pads 441 and the brake disc 421, and thus a braking effect is generated, which depends on the load generated by the electric motor 32 and transmitted to the brake pads 441 by the motion conversion unit 34.

[0027] The control of the electric motor 32 is also based on motor parameters, namely current intensity and voltage, and sensor signals from the vibration sensor 52. The evaluation unit 54 determines the current clamping force between the brake pads 441 and the brake disc 421, which is crucial for the control of the electric motor 32, from the sensor signals of the vibration sensor 52. Here, the vibration characteristics of the brake component 46, i.e., the brake caliper 461, which vary according to the clamping or load of the brake caliper 461 (caused by the clamping of the brake disc 421 between the brake pads 441 and the support of the brake pads 441 on the brake caliper 461), are utilized. Specifically, the body vibration with a specific vibration amplitude and frequency caused by clamping is determined, and the clamping force is inferred from this. In particular, spectral changes and frequency shifts, especially shifts in the resonant frequency, occur according to the clamping of the brake component 46. The clamping force can be estimated based on the determined spectral changes caused by specific clamping or load.

[0028] Figure 2 A second embodiment of the braking system 10 is shown. (Compared to...) Figure 1 The key difference in the first embodiment is that the braking device 40 is not constructed as a brake disc device 401, but rather as a brake drum device 402. The brake drum device 402 includes two vehicle-side braking components 44 (currently two pivotally supported brake pads 442) and a wheel-side braking component 42 (currently a brake drum 422). The actuator device 30 is operatively connected to the brake pads 442. A vibration sensor 52 is fixed to the brake drum 442 and thus detects vibrations of the brake drum 442 itself. The operating principle of this braking system 10 corresponds to... Figure 1 The working principle of the first implementation method.

[0029] Figure 3 An example is shown according to Figure 1 and Figure 2 The spectrum of the sensor signal from the vibration sensor 52 in an embodiment of the braking system 10 is shown. The solid line shows the spectrum when the braking device 40 is not operated, i.e., when there is no braking process. The dashed line shows the spectrum during the braking process. According to... Figure 3 The vibration sensor 52 and / or the braking components 42, 46 supporting the vibration sensor 52 are vibrated, resulting in a predetermined body vibration of the vibration sensor 52 or the braking components 42, 46. The change in vibration is determined based on the initial body vibration caused by this vibration excitation, and the clamping force required to control the motor 32 is determined accordingly. Alternatively, the clamping force can be determined passively without vibration excitation of the vibration sensor 52 and / or the braking components 42, 46, where the change in the frequency spectrum can also be determined and the clamping force can be estimated accordingly.

[0030] List of reference numerals

[0031] 10 Braking System

[0032] 20 Pedal Device

[0033] 22 Brake Pedal

[0034] 24 Reset Unit

[0035] 26 Brake Pedal Sensors

[0036] 30 actuator devices

[0037] 31 drive units

[0038] 32 electric motors

[0039] 34 motion conversion units

[0040] 40 Braking System

[0041] 401 disc brake system

[0042] 402 Drum Brake Device

[0043] 42 Vehicle side braking components

[0044] 421 Brake Disc

[0045] 422 brake caliper

[0046] 44 Body side braking components

[0047] 441 brake pads

[0048] 46 Another braking component

[0049] 461 brake caliper

[0050] 50 sensor devices

[0051] 52 vibration sensors

[0052] 54 evaluation units

[0053] 60 control unit

Claims

1. A sensor device for a braking system (10) of a motor vehicle, said sensor device having: Vibration sensor (52), configured to be fixed to the braking components (42; 46) of the braking system (10) and to detect the body vibration of the braking components (42; 46); and An evaluation unit (54) is signal-connected to the vibration sensor (52) and configured to estimate the clamping force between at least one vehicle-side braking component (44) of the braking system (10) and a wheel-side braking component (42) that interacts with the vehicle-side braking component (44) during braking, based on the sensor signal from the vibration sensor (52).

2. The sensor device according to claim 1, characterized in that, The evaluation unit (54) is configured to determine the moment when the vehicle side brake component (44) abuts against the wheel side brake component (42) from the determined clamping force.

3. The sensor device according to any one of the preceding claims, characterized in that, The evaluation unit (54) is configured to actively determine the body vibration of the braking component (42; 46) based on the sensor signal of the vibration sensor (52), such that the vibration sensor (52) and / or the braking component (42; 46) receiving the vibration sensor are pre-defined to be excited.

4. The sensor device according to claim 1 or 2, characterized in that, The evaluation unit (54) is configured to passively determine the body vibration of the braking component (42; 46) based on the sensor signal of the vibration sensor (52).

5. An actuator device for a braking system (10), said actuator device having: Construct a drive unit (31) for operating the braking device (40). The sensor device (50) according to any one of claims 1 to 4; and Control unit (60) that is signal-connected to the drive unit (30) and the sensor unit (50).

6. A braking system for a motor vehicle, the braking system having a braking device (40) and an actuator device (30) according to claim 5.

7. The braking system according to claim 6, characterized in that, The device includes a pedal assembly (20) having a brake pedal (22) and a brake pedal sensor (26) configured to detect pedal travel and / or operating force when the brake pedal (22) is applied by a person. The brake pedal sensor (26) is signal-connected to the control unit (60) of the actuator assembly (30).

8. The braking system according to claim 6 or 7, characterized in that, The braking device (40) is a drum brake (401) or a disc brake (402).

9. The braking system according to any one of claims 6 to 8, characterized in that, The vibration sensor (52) is positioned outside the direct force flow.

10. The braking system according to claim 9, characterized in that, The vibration sensor (52) is arranged on the outer side of the braking component (42; 46) facing the external environment.

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