JP2022057147A - Vehicular brake device - Google Patents

Abstract

To provide a vehicular brake device which can inhibit increase of motor starting current when a parking brake force is generated.SOLUTION: A vehicular brake device 100 includes: a housing having a through hole; a screw shaft which is guided by an inner peripheral surface of the housing and penetrates through the through hole; an elastic member disposed at a portion where the screw shaft driven by a motor and the housing are butted; and a torque control unit which controls torque of the motor based on a motor current of the motor detected in a process in which the elastic member is compressed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicle braking device.

Patent Document 1 discloses a vehicle braking device that constantly determines the return position of the electric actuator when the parking braking force is released. The vehicle brake device of Patent Document 1 includes a screw shaft connected to a brake cable, a motor for driving the screw shaft, and a regulating means for regulating the position of origin of the screw shaft when the parking braking force is released.

In this vehicle braking device, when the parking braking force is released, the screw shaft moves in the brake release direction due to the rotation of the motor, and when the regulating means reaches the origin setting position, the motor current flowing through the motor reaches a predetermined value. Upon reaching it, the motor is stopped.

JP-A-2017-74809

However, in the prior art of Patent Document 1, when the regulating means hits the origin setting position, the motor current suddenly rises, and the regulating means moves to the origin setting position (for example, in the housing) due to the excessive motor torque corresponding to this current. It is tightened to the peripheral part). Therefore, when the parking brake force is generated, the tightening torque of the regulating means becomes large, and a large motor starting current is required to loosen the screw shaft. Therefore, the control circuit of the motor may become large and its configuration may become complicated.

An object of the present invention is to provide a vehicle braking device capable of suppressing an increase in a motor starting current when a parking braking force is generated.

In the vehicle braking device of the present invention, a housing having a through hole, a screw shaft guided by the inner peripheral surface of the housing and penetrating the through hole, and the screw shaft driven by a motor and the housing abut against each other. It includes an elastic member arranged in a portion to be formed, and a torque control unit that controls the torque of the motor based on the motor current of the motor detected in the process of compressing the elastic member.

According to the present invention, it is possible to obtain a vehicle braking device capable of suppressing an increase in the motor starting current when a parking braking force is generated.

The figure which shows the structural example of the vehicle brake device 1 which concerns on embodiment of this invention. The figure which shows the structural example of the screw shaft 20 and the current reduction structure 70. External view of elastic member 72 Sectional drawing of elastic member 72 The figure which shows the structural example of the screw shaft drive gear 50 The figure which shows the structural example of the control unit 40 A flowchart for explaining the operation of the vehicle brake device 1. The figure which shows the relationship between the movement amount of a screw shaft 20 and a motor current. The figure which shows the state which the elastic member 72 is compressed The figure which shows the relationship between the rotational torque of a motor 30 and a motor current.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. From FIG. 1, an orthogonal coordinate system including an X-axis, a Y-axis, and a Z-axis is shown. Further, the direction indicated by the arrow on the X-axis is the plus X-axis direction, and the direction opposite to the direction is the minus X-axis direction. The direction indicated by the arrow on the Y-axis is the plus Y-axis direction, and the direction opposite to the direction is the minus Y-axis direction. In the Z-axis, the direction indicated by the arrow is the plus Z-axis direction, and the direction opposite to the direction is the minus Z-axis direction.

FIG. 1 is a diagram showing a configuration example of a vehicle brake device 1 according to an embodiment of the present invention. The vehicle brake device 1 is a device for generating a parking brake force on, for example, a drum brake of a vehicle, or releasing the parking brake force. The arrow D in the figure indicates the direction in which the screw shaft 20 moves when the parking brake is released.

The vehicle brake device 1 includes a housing 10, a screw shaft 20, a motor 30, a control unit 40, a screw shaft drive gear 50, a bearing 60, and a current reduction structure 70.

Inside the housing 10, a first gear 32 connected to the motor shaft 31, a second gear 33 that meshes with the first gear 32, and a screw shaft drive gear 50 that meshes with the second gear 33 are provided. Further, inside the housing 10, a screw shaft 20 arranged in the screw shaft drive gear 50 and a bearing 60 that rotatably supports the screw shaft drive gear 50 are provided.

When the rotation of the motor 30 is transmitted to the motor shaft 31, the rotation of the motor 30 is decelerated by the gears of the first gear 32, the second gear 33, and the screw shaft drive gear 50. When the screw shaft drive gear 50 rotates, the screw shaft 20 moves back and forth with respect to the housing 10.

The current reduction structure 70 is a member for alleviating a sudden increase in the motor current due to the screw shaft 20 reaching the abutting position when the parking braking force is released. The current reduction structure 70 closes the peripheral region excluding the central portion of the through hole 10b formed in the housing 10 (that is, the peripheral region of the opening formed in the protrusion protruding in the Y-axis direction in the housing 10). It is fixed at 10. An opening through which the screw shaft 20 penetrates is provided in the central portion of the current reduction structure 70.

Next, the configurations of the screw shaft 20, the current reduction structure 70, and the screw shaft drive gear 50 will be described with reference to FIGS. 2 to 5.

2 is a diagram showing a configuration example of the screw shaft 20 and the current reduction structure 70, FIG. 3 is an external view of the elastic member 72, FIG. 4 is a cross-sectional view of the elastic member 72, and FIG. 5 is a configuration example of the screw shaft drive gear 50. It is a figure which shows.

(Structure of current reduction structure 70)
As shown in FIG. 2, the current reduction structure 70 includes a washer 71, an elastic member 72, and a washer 73.

The washer 71, the elastic member 72, and the washer 73 are arranged in the order of the washer 73, the elastic member 72, and the washer 71 in the plus Y-axis direction.

An opening through which the screw shaft 20 penetrates is formed in the center of each of the washer 71, the elastic member 72, and the washer 73. The diameter of each opening is substantially equal to the diameter of the shaft body 21 of the screw shaft 20.

The washer 71 is provided in the housing 10 so as to close the peripheral region excluding the central portion of the through hole 10b of the housing 10 shown in FIG. 1 (that is, the peripheral region of the opening formed in the protrusion protruding in the Y-axis direction in the housing 10). An annular washer that is fixed, for example, made of a metal member.

As shown in FIGS. 3 and 4, the elastic member 72 is, for example, a truncated cone-shaped disc spring made of a metal member. The elastic member 72 is made of a material whose elastic modulus is lower than the elastic modulus of the material constituting the washer 71, or a material having an elastic modulus lower than the elastic modulus of the material constituting the closing member integrally formed with the housing 10. It is preferable to do so. The closing member integrally formed with the housing 10 closes the peripheral region excluding the central portion of the through hole 10b of the housing 10 (that is, the peripheral region of the opening formed in the protrusion protruding in the Y-axis direction in the housing 10). It is an annular member integrally formed with the housing 10. As a result, when the elastic member 72 is compressed in the sections P1 and P2 described later, the washer 71 or the housing 10 having a low elastic modulus is suppressed from being deformed, so that the elastic member is elastic while suppressing the displacement of the forward abutting position. The elastic member 72 having a low coefficient is gradually deformed, so that a sudden increase in the motor current can be suppressed.

The elastic member 72 is not limited to the truncated cone-shaped disc spring, and may be an elastically deformable member such as a coil spring.

However, by adopting a disc spring, a member that can be elastically deformed can be easily provided in a narrow space inside the housing 10, so that the vehicle brake device 1 can be miniaturized. Further, since the disc spring is a general-purpose member that is generally used, it is highly reliable and can suppress an increase in the manufacturing cost of the vehicle brake device 1. Further, the material of the elastic member 72 is not limited to metal, and may be resin, rubber, or the like.

At the center of the elastic member 72, an opening 72a into which the screw shaft 20 shown in FIG. 2 is inserted is formed. The inner peripheral surface 72b of the elastic member 72 is in contact with the outer peripheral surface of the screw shaft 20.

The outer peripheral surface 72e of the elastic member 72 is in contact with, for example, a step portion formed in the through hole 10b of the housing 10 shown in FIG.

Further, the first end surface 72c of the elastic member 72 in the minus Y-axis direction faces the washer 73 shown in FIG. 2, and the second end surface 72d of the elastic member 72 in the plus Y-axis direction is the washer 71 shown in FIG. Facing.

When the screw shaft 20 moves in the plus Y-axis direction, the elastic member 72 bends while being compressed by the washer 73 that moves with the screw shaft 20 and the washer 71 that is fixed to the housing 10. After that, when the screw shaft 20 moves in the minus Y-axis direction, the elastic member 72 is restored to its original shape (conical cone shape shown in FIG. 4).

(Structure of screw shaft 20)
As shown in FIG. 2, the screw shaft 20 includes a columnar shaft body 21 extending in the Y-axis direction and a stopper 22 formed at a position near the center of the shaft body 21 in the Y-axis direction.

Further, the screw shaft 20 has a male screw portion 23 formed in the region from the stopper 22 to the end portion of the shaft body 21 in the minus Y-axis direction, and a cable connecting portion provided at the end portion of the shaft body 21 in the plus Y-axis direction. 24 and.

The end of the male screw portion 23 in the minus Y-axis direction is screwed into the female screw portion 51a of the screw shaft support portion 51 in the screw shaft drive gear 50 shown in FIG. Details of the configuration of the screw shaft drive gear 50 will be described later.

The screw shaft 20 shown in FIG. 2 is screwed into the female screw portion 51a shown in FIG.

A D-cut surface 20a is formed on the outer peripheral surface of the screw shaft 20 shown in FIG. 2. Further, a D-cut surface is also formed on the inner peripheral surface 10c forming the through hole of the housing 10 shown in FIG. The rotation of the screw shaft 20 is suppressed by the D-cut surface 20a formed on the screw shaft 20 coming into contact with the D-cut surface formed on the inner peripheral surface 10c of the housing 10. Therefore, when the screw shaft drive gear 50 rotates, the screw shaft 20 moves back and forth in the plus Y-axis direction and the minus Y-axis direction while the rotation is suppressed by the D-cut surface 20a of the screw shaft 20.

As shown in FIG. 2, the stopper 22 is a metal annular member formed on the outer peripheral surface of the shaft body 21 adjacent to the male screw portion 23.

The diameter of the stopper 22 is larger than the inner diameter of the washer 73. The stopper 22 contacts the washer 73 when the screw shaft 20 moves in the plus Y-axis direction, and presses the washer 73 when the screw shaft 20 further moves in the plus Y-axis direction. As a result, the elastic member 72 provided between the washer 73 and the washer 71 is compressed and bends in the plus Y-axis direction.

The cable connecting portion 24 is connected to, for example, one end of a brake cable (not shown). The other end of the brake cable is connected to, for example, a brake lever provided on a vehicle drum brake.

For example, when the screw shaft 20 retracts, the brake cable connected to the cable connecting portion 24 moves to the vehicle brake device 1 side, so that a parking braking force is generated in the drum brake of the vehicle. Retreat means that the screw shaft 20 moves from the outside to the inside of the housing 10.

On the other hand, when the screw shaft 20 advances, the brake cable connected to the cable connecting portion 24 moves to the side opposite to the vehicle brake device 1 side, so that the parking braking force is released. Forwarding means that the screw shaft 20 moves from the inside of the housing 10 toward the outside of the housing 10.

(Structure of screw shaft drive gear 50)
As shown in FIG. 5, the screw shaft drive gear 50 includes a cylindrical screw shaft support portion 51 that supports the screw shaft 20 and a gear portion 52.

A female screw portion 51a is formed on the inner peripheral surface of the screw shaft support portion 51. The male screw portion 23 of FIG. 2 is inserted into the opening 51b of the screw shaft support portion 51, and the male screw portion 23 is screwed into the female screw portion 51a.

The gear portion 52 is a gear that meshes with the second gear 33 shown in FIG. 1, and is formed coaxially with the screw shaft support portion 51 on the outer peripheral surface of the screw shaft support portion 51.

The width of the gear portion 52 in the Y-axis direction is smaller than the width of the second gear 33 in the Y-axis direction shown in FIG. With this configuration, even if the screw shaft drive gear 50 moves forward and backward with the advance / retreat movement of the screw shaft 20, the rotational force can be transmitted to the screw shaft drive gear 50.

Next, a configuration example of the control unit 40 will be described with reference to FIG. FIG. 6 is a diagram showing a configuration example of the control unit 40.

The control unit 40 is driven by a motor drive unit 41 that drives the motor 30 by the electric power supplied from the power supply 200, a current detection unit 42 that detects the current (motor current) supplied from the motor drive unit 41 to the motor 30. A signal generation unit 43 is provided.

The drive signal generation unit 43 controls the rotation direction, rotation torque, rotation speed, etc. of the motor 30 based on the operation command output from the brake switch 100 and the motor current detected by the current detection unit 42. Generate a drive signal. The drive signal generation unit 43 is an example of a torque control unit.

When an operation command is output from the brake switch 100, the control unit 40 that has received the operation command supplies a current to the motor 30 to rotate the motor 30. When the gear portion 52 rotates according to the rotation of the motor 30, the screw shaft 20 moves between the forward side abutting position and the backward side abutting position.

The forward-side abutting position is the stop position of the advanced screw shaft 20. The retracted side abutting position is the stop position of the retracted screw shaft 20.

(Operation of vehicle brake device 1)
Next, the operation of the vehicle brake device 1 will be described with reference to FIGS. 7 to 10.

7 is a flowchart for explaining the operation of the vehicle braking device 1, FIG. 8 is a diagram showing the relationship between the movement amount of the screw shaft 20 and the motor current, and FIG. 9 is a diagram showing a state in which the elastic member 72 is compressed. , FIG. 10 is a diagram showing the relationship between the rotational torque of the motor 30 and the motor current.

The horizontal axis of FIG. 8 represents the position of the screw shaft 20 in the Y-axis direction, and the vertical axis of FIG. 8 represents the motor current. P0 in the figure is a position where the stopper 22 of the screw shaft 20 is separated from the washer 73 by a certain distance. P1 represents the position when the stopper 22 provided on the screw shaft 20 comes into contact with the washer 73. P2 represents the above-mentioned forward side abutting position.

In FIG. 9, in order from the top, a screw shaft 20 that advances from P0 to P1, a screw shaft 20 that advances from P1 to P2, and a screw shaft 20 that reaches P2 (advance side abutting position) are shown. It is shown.

Further, the horizontal axis of FIG. 10 represents the rotational torque of the motor 30, and the vertical axis of FIG. 10 represents the motor current.

In step S1, for example, when an operation command for releasing the parking brake force is output from the brake switch 100 shown in FIG. 6, the control unit 40 that receives the operation command advances the motor so as to advance the screw shaft 20. Start the rotation of 30.

When the screw shaft 20 advances, the stopper 22 of the screw shaft 20 approaches the washer 73 as shown in the first figure from the top of FIG. When the screw shaft 20 is further advanced, the stopper 22 of the screw shaft 20 comes into contact with the washer 73 as shown in the second figure from the top of FIG.

When the screw shaft 20 further advances in this state, the screw shaft 20 tries to move forward against the restoring force of the elastic member 72, so that the load on the motor 30 increases. Therefore, as shown in the section P1 to P2 in FIG. 8, the motor current gradually increases.

In step S2, the drive signal generation unit 43 of the control unit 40 determines whether or not the increased motor current is equal to or higher than the first threshold value by comparing the value of the motor current with the preset first threshold value. ..

In step S2, when the motor current is less than the first threshold value (steps S2 and NO), the drive signal generation unit 43 continues the process of step S2 until the motor current becomes equal to or more than the first threshold value.

In step S2, when the motor current becomes equal to or higher than the first threshold value (steps S2, YES), the drive signal generation unit 43 executes the process of step S3.

When the motor current becomes equal to or higher than the first threshold value, in step S3, the drive signal generation unit 43 reduces the voltage applied to the motor 30 by changing the on-time width (Duty ratio) of the drive signal. For example, as shown in FIG. 10, the voltage applied to the motor 30 is set to 4 [V]. In this case, a motor current (for example, 7 [A]) having a value capable of advancing the screw shaft 20 while compressing the elastic member 72 flows through the motor 30.

By reducing the voltage in this way, the rotational torque of the motor 30 can be reduced while advancing the screw shaft 20. After reducing the rotational torque, the drive signal generation unit 43 executes the process of step S4.

In step S4, the drive signal generation unit 43 determines whether or not the motor current is equal to or higher than the second threshold value by comparing the value of the motor current with the preset second threshold value. The second threshold value is a threshold value higher than the first threshold value, and is set to, for example, a value at which it can be determined that the screw shaft 20 has reached the forward side abutting position. The upper limit of the second threshold value is set to, for example, a value equal to or less than the motor starting current required to generate the parking braking force.

In step S4, when the motor current is less than the second threshold value (steps S4, NO), the drive signal generation unit 43 repeats the processes after step S3 until the motor current becomes equal to or more than the second threshold value.

In step S4, when the motor current becomes equal to or higher than the second threshold value (step S4, YES), the drive signal generation unit 43 stops the operation of the motor 30 because the screw shaft 20 has reached the forward side abutting position (step S4, YES). Step S5).

Here, the motor current when the screw shaft 20 reaches the forward side abutting position is, for example, about 7 [A] as described above, whereas the motor start required to generate the parking braking force is started. The current (“starting current” shown in FIG. 10) has a larger value.

This is because when the screw shaft 20 reaches the forward side abutting position, the screw shaft 20 needs to rotate in the reverse direction against the tightening torque generated between the screw shaft 20 and the housing 10. ..

The conventional vehicle brake device is not provided with the current reduction structure (elastic member 72, etc.) according to the present embodiment, and controls the rotational torque when the screw shaft reaches the forward side abutting position. It has not been. Therefore, for example, when the motor current suddenly increases due to the screw shaft reaching the forward side abutting position, the rotational torque also increases, so that the above-mentioned tightening torque increases.

Therefore, in order to generate the parking brake force, when the screw shaft 20 is rotated in the reverse direction, it is necessary to generate a large rotational torque exceeding this tightening torque. In this case, a motor 30 having a large rating and a drive mechanism having sufficient strength against a large rotational torque are required.

On the other hand, the vehicle brake device 1 according to the embodiment of the present invention is provided with the elastic member 72, so that the motor current gradually increases in the process in which the screw shaft 20 compresses the elastic member 72. Using the motor current detected at this time, the rotational torque when the screw shaft 20 reaches the forward side abutting position can be easily controlled.

As a result, the increase in tightening can be suppressed, so that the increase in the motor starting current when the parking braking force is generated can be suppressed. That is, the rotational torque when the parking brake force is generated can be reduced. As a result, it is possible to adopt a motor 30 having a small rating and a drive mechanism having an appropriate strength against a large rotational torque, and it is possible to reduce the size of the vehicle brake device 1.

Further, by reducing the motor starting current when the parking brake force is generated, deterioration of the components (for example, electrolytic capacitor) of the control unit 40 can be suppressed. Therefore, in addition to the above-mentioned effects, the reliability of the vehicle brake device 1 can be improved.

It is possible to control the rotational torque by adding a sensor for detecting the rotation speed of the motor, a sensor for detecting the front abutment position, and the like to the conventional vehicle brake device. However, in this case, the structure of the vehicle brake device may become complicated and the reliability may decrease.

According to the vehicle brake device 1 according to the embodiment of the present invention, the rotational torque can be controlled only by changing the control program of the control unit 40 without adding these sensors. Therefore, the vehicle brake device Since the reliability of 1 is improved and the step of assembling these sensors can be omitted, the manufacturing cost of the vehicle brake device 1 can be reduced.

The drive signal generation unit 43 may be configured to control the rotational torque according to the time change rate of the motor current.

For example, when the first time change rate is larger than the second time change rate, the drive signal generation unit 43 sets the rotational torque generated when the motor current indicating the first time change rate flows. It is smaller than the rotational torque generated when the motor current, which indicates the rate of change over time, flows.

The second time change rate is the time change rate of the motor current detected when the elastic member is not compressed (for example, before P1 shown in FIG. 8). The first time change rate is the time change rate of the motor current detected in the process of compressing the elastic member (for example, after P1 shown in FIG. 8).

With this configuration, compared to the case where a plurality of threshold values are set and the rotational torque is controlled by comparing the motor current with these threshold values, the rotational torque can be controlled more finely, and the tightening torque can be increased. It can be further suppressed.

It should be noted that, for example, the following aspects are also understood to belong to the technical scope of the present disclosure.

(1) In the vehicle braking device, a housing having a through hole, a screw shaft guided by the inner peripheral surface of the housing and penetrating the through hole, and the screw shaft driven by a motor and the housing abut against each other. It includes an elastic member arranged in a portion to be formed, and a torque control unit that controls the torque of the motor based on the motor current of the motor detected in the process of compressing the elastic member.

(2) The elastic member is a disc spring.

(3) The torque control unit measures the torque generated between the time when the motor current exceeds the first threshold value and the time when the motor current reaches the second threshold value higher than the first threshold value when the motor current is less than the first threshold value. Make it smaller than the generated torque.

(4) In the torque control unit, the first time change rate of the motor current detected in the process of compressing the elastic member is the second of the motor current detected when the elastic member is not compressed. When it is larger than the time change rate of, the torque generated when the motor current indicating the first time change rate flows is smaller than the torque generated when the motor current indicating the second time change rate flows. do.

(5) The elastic modulus of the elastic member is made of a material lower than the elastic modulus of the material constituting the annular washer fixed to the housing so as to close the peripheral region other than the central portion of the through hole. There is.

(6) The elastic modulus of the elastic member is lower than the elastic modulus of the material constituting the closed member integrally formed with the housing so as to close the peripheral region other than the central portion of the through hole. ing.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope of the claims and equality.

The embodiment of the present invention has been described above. The above description is an example of a preferred embodiment of the present invention, and the scope of the present invention is not limited thereto. That is, the description of the configuration of the device and the shape of each part is an example, and it is clear that various changes and additions to these examples are possible within the scope of the present invention.

The vehicle braking device according to the present invention is useful as a device capable of suppressing an increase in the motor starting current when a parking braking force is generated.

1 Vehicle brake device 10 Housing 10a Inner peripheral surface 10b Through hole 10c Inner peripheral surface 20 Thread shaft 20a D Cut surface 21 Shaft body 22 Stopper 23 Female thread part 24 Cable connection part 30 Motor 31 Motor shaft 32 1st gear 33 2nd gear 40 Control part 41 Motor drive part 42 Current detection part 43 Drive signal generation part 50 Thread shaft drive gear 51 Thread shaft support part 51a Female thread part 51b Opening 52 Gear part 60 Bearing 70 Current reduction structure 71 Washer 72 Elastic member 72a Opening 72b Inner peripheral surface 72c Axial first end surface 72d Axial second end surface 72e Outer surface 73 Washer 100 Brake switch 200 Power supply

Claims (6)

A housing with through holes and
A screw shaft guided by the inner peripheral surface of the housing and penetrating the through hole,
An elastic member arranged at a portion where the screw shaft driven by the motor and the housing are abutted against each other.
A torque control unit that controls the torque of the motor based on the motor current of the motor detected in the process of compressing the elastic member.
Brake device for vehicles equipped with. The vehicle braking device according to claim 1, wherein the elastic member is a disc spring. The torque control unit measures the torque generated between the time when the motor current exceeds the first threshold value and the time when the motor current reaches the second threshold value higher than the first threshold value, and the torque generated when the motor current is less than the first threshold value. The vehicle braking device according to claim 1 or 2, which is smaller than the above. In the torque control unit, the first time change rate of the motor current detected in the process of compressing the elastic member is the second time change of the motor current detected when the elastic member is not compressed. When it is larger than the rate, the torque generated when the motor current indicating the first time change rate flows is smaller than the torque generated when the motor current indicating the second time change rate flows. The vehicle braking device according to 1 or 2. Claimed that the elastic modulus of the elastic member is lower than the elastic modulus of the material constituting the annular washer fixed to the housing so as to close the peripheral region except the central portion of the through hole. The vehicle braking device according to any one of 1 to 4. The elastic modulus of the elastic member is made of a material lower than the elastic modulus of the material constituting the closed member integrally formed with the housing so as to close the peripheral region other than the central portion of the through hole. Item 6. The vehicle braking device according to any one of Items 1 to 5.

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