JP4060076B2 - Electric disc brake and its control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric disc brake and its controlling program capable of eliminating the influence of temperature drift generated during traveling. <P>SOLUTION: The electric disc brake is provided with an electric motor 19, a position detecting means 20 detecting the motor rotational position of the electric motor 19, a thrust detecting means 46 detecting piston thrust which a piston 40 is received, and a controlling means controlling the electric motor 19 to make the piston generate target thrust by thrust control based on the piston thrust detected by the thrust detecting means 46 and position control based on the motor rotational position detected by the position detecting means 20. The controlling means detects the zero point of piston thrust in the thrust detecting means 46 in view of the quantity change of the motor rotational position and piston thrust. <P>COPYRIGHT: (C)2003,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric disk brake that generates a braking force by converting a rotary motion of an electric motor into a linear motion of a piston, and a control program therefor.
[0002]
[Prior art]
As an electric disc brake that generates a braking force by converting the rotary motion of the electric motor into a linear motion of the piston, for example, the rotary motion of the electric motor and the electric motor is converted into the linear motion of the piston, and the brake pad is disced by the piston. There is an electric disk brake having a conversion mechanism part to be brought into contact with, a position detection means for detecting the motor rotation position of the electric motor, and a thrust detection means for detecting a piston thrust received by the piston. Some are disclosed in the publication.
[0003]
By the way, the frictional heat due to braking, the heat generation of the electric motor, the temperature change of the surrounding environment, etc. cause the so-called temperature drift that the output value of the electric disc brake is affected by the built-in thrust detecting means. .
[0004]
For this reason, the electric disc brake disclosed in the above publication performs zero point correction in which the output of the thrust detecting means at the motor position where no piston thrust is clearly generated is zero.
[0005]
[Problems to be solved by the invention]
As described above, when the zero point correction is performed so that the output of the thrust detection means at the motor position where the piston thrust is clearly not generated is zero, in order to perform such zero point correction, the piston is set to a position higher than the set position. I have to go back. For this reason, the zero point correction of the thrust detection means cannot be performed particularly during traveling. However, since temperature drift also occurs due to frictional heat from braking during driving and the effect of heat generated by the electric motor, if the zero point of the thrust detection means cannot be corrected during driving as described above, temperature drift that occurs during driving will occur. There was a problem that the influence of could not be eliminated.
[0006]
Accordingly, an object of the present invention is to provide an electric disc brake and a control program therefor that can eliminate the influence of temperature drift that has occurred during traveling.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an electric disc brake according to claim 1 of the present invention is an electric motor and a conversion mechanism for converting the rotational motion of the electric motor into linear motion of a piston and causing the brake pad to contact the disc with the piston. , Position detection means for detecting the motor rotation position of the electric motor, thrust detection means for detecting the piston thrust received by the piston, thrust control based on the piston thrust detected by the thrust detection means, and position detection And an electric disc brake having control means for controlling the electric motor so as to generate a target thrust force on the piston by position control based on the motor rotation position detected by the means. Rotate the electric motor in the direction to close the pad clearance when the accelerator is released Close the pad clearance , The motor rotation position But change In the middle of , Change amount of the piston thrust Detect the piston thrust value when switching from a zero state to a non-zero state, subtract this piston thrust value, The zero point of the piston thrust in the thrust detection means correction It is characterized by doing.
[0008]
Thus, the control means detects the zero point of the piston thrust in the thrust detection means from the change amount of the motor rotation position and the change amount of the piston thrust. There is no need to retreat.
[0010]
Also, when the vehicle is running and the accelerator is released, rotate the electric motor in the direction to close the pad clearance. Close pad clearance In that case, zero point of piston thrust correction Therefore, for example, the zero point of the piston thrust is set at a position where there is a change amount of the motor rotation position and the state where the change amount of the piston thrust is not changed to a state where the change occurs. correction can do.
[0011]
The electric disk brake according to claim 2 of the present invention includes an electric motor, a conversion mechanism that converts the rotational movement of the electric motor into a linear movement of the piston and makes the brake pad contact the disk with the piston, and the electric motor of the electric motor Position detection means for detecting the motor rotation position, thrust detection means for detecting the piston thrust received by the piston, thrust control based on the piston thrust detected by the thrust detection means, and motor rotation detected by the position detection means An electric disc brake having control means for controlling the electric motor so as to generate a target thrust force on the piston by position control based on the position, wherein the control means releases the accelerator when the vehicle is running. Rotate the electric motor in the direction to close the pad clearance when Close the pad clearance , The motor rotation position But change In the middle of , Change amount of the piston thrust When switching from zero to non-zero The motor rotation position is detected.
[0012]
Thus, since the control means detects the motor rotation position where the piston thrust is generated from the change amount of the motor rotation position and the change amount of the piston thrust, it is not necessary to retreat the piston beyond the set position.
[0014]
In addition, when the vehicle is running and the accelerator is released, that is, when the brake operation is predicted, the electric motor is rotated in the direction to close the pad clearance. Close pad clearance In this case, since the motor rotation position at which the piston thrust is generated is detected, the motor rotation position at which the piston thrust is generated can be detected every time the pad clearance is reduced.
The electric disc brake according to claim 3 of the present invention is the zero point of the piston thrust with respect to the electric disc brake according to claim 1 or 2. Correction Or change amount of the piston thrust When switching from zero to non-zero The motor rotation position of detection The After that, the electric motor is returned in the direction of opening the pad clearance so that the piston thrust is almost zero.
[0015]
According to a fourth aspect of the present invention, there is provided an electric disc brake control program comprising: an electric motor; a conversion mechanism that converts a rotational motion of the electric motor into a linear motion of a piston and causes the brake pad to contact the disc with the piston; Position detection means for detecting the motor rotation position of the electric motor, thrust detection means for detecting the piston thrust received by the piston, thrust control based on the piston thrust detected by the thrust detection means, and detection by the position detection means A control program for an electric disc brake having control means for controlling the electric motor so that the piston generates a target thrust by position control based on the motor rotation position, wherein the vehicle is running and the accelerator is released. Rotate the electric motor in the direction to reduce the pad clearance when Close the pad clearance , The motor rotation position But change In the middle of , Change amount of the piston thrust Detect the piston thrust value when switching from a zero state to a non-zero state, subtract this piston thrust value, The zero point of the piston thrust in the thrust detection means correction It is characterized by doing.
[0016]
Thus, the zero point of the piston thrust in the thrust detecting means is determined from the amount of change in the motor rotational position and the amount of change in the piston thrust. correction Therefore, it is not necessary to retreat the piston beyond the set position in order to perform the zero point correction.
Also, when the vehicle is running and the accelerator is released, rotate the electric motor in the direction to close the pad clearance. Close pad clearance In that case, zero point of piston thrust correction Therefore, for example, the zero point of the piston thrust is set at a position where there is a change amount of the motor rotation position but the state where there is no change amount of the piston thrust is changed to a generated state. correction can do.
[0017]
An electric disk brake control program according to claim 5 of the present invention includes an electric motor, a conversion mechanism unit that converts the rotational motion of the electric motor into a linear motion of a piston and causes the brake pad to contact the disc with the piston, Position detection means for detecting the motor rotation position of the electric motor, thrust detection means for detecting the piston thrust received by the piston, thrust control based on the piston thrust detected by the thrust detection means, and detection by the position detection means A control program for an electric disc brake having control means for controlling the electric motor so that the piston generates a target thrust by position control based on the motor rotation position, wherein the vehicle is running and the accelerator is released. Rotate the electric motor in the direction to reduce the pad clearance when Close the pad clearance , The motor rotation position But change In the middle of , Change amount of the piston thrust When switching from zero to non-zero The motor rotation position is detected.
[0018]
Thus, since the motor rotation position where the piston thrust is generated is detected from the change amount of the motor rotation position and the change amount of the piston thrust, it is not necessary to retreat the piston beyond the set position.
In addition, when the vehicle is running and the accelerator is released, that is, when the brake operation is predicted, the electric motor is rotated in the direction to close the pad clearance. Close pad clearance In this case, since the motor rotation position at which the piston thrust is generated is detected, the motor rotation position at which the piston thrust is generated can be detected every time the pad clearance is reduced.
According to a sixth aspect of the present invention, there is provided a program for controlling an electric disk brake according to the fourth or fifth aspect, wherein the piston thrust zero point is obtained. Correction Or change amount of the piston thrust When switching from zero to non-zero The motor rotation position of detection The After that, the electric motor is returned in the direction of opening the pad clearance so that the piston thrust is almost zero.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
An electric disk brake and its control program according to an embodiment of the present invention will be described below with reference to FIGS.
[0020]
As shown in FIG. 1, in the electric caliper 10 of the electric disc brake of this embodiment, a caliper body 12 is disposed on one side (usually inside the vehicle body) of a disc 11 that rotates with a wheel (not shown). The caliper body 12 is integrally coupled with a claw portion 13 that is formed in a substantially C shape and extends across the disk 11 to the opposite side. Brake pads 14 and 15 are provided on both sides of the disk 11, that is, between the disk 11 and the caliper main body 12 and between the front ends of the claw parts 13. The brake pads 14 and 15 are supported by a carrier 16 fixed to the vehicle body so as to be movable in the axial direction of the disk 11 so as to receive a braking torque by the carrier 16. , And is guided to be slidable along the axial direction of the disk 11 by a slide pin (not shown) attached to the carrier 16.
[0021]
A caliper-shaped case 18 is coupled to the caliper body 12 by a bolt 17, and an electric motor 19 and a position detector (position detecting means) 20 are provided in the case 18. On the other hand, a ball ramp mechanism 21 and a speed reduction mechanism 22 are inserted into the caliper body 12. A cover 23 is attached to the rear end portion of the case 18 with a bolt 24.
[0022]
The electric motor 19 includes a stator 25 fixed to the inner periphery of the case 18, and a rotor 28 inserted into the stator 25 and rotatably supported by the case 18 by bearings 26 and 27. The position detector 20 includes a resolver stator 29 fixed to the case 18 side and a resolver rotor 30 attached to the rotor 28. Based on these relative rotations, the rotational position of the rotor 28, that is, the motor rotational position of the electric motor 19 is determined. It is to detect.
[0023]
The ball ramp mechanism 21 includes annular first and second disks 32 and 33 and a plurality of balls (steel balls) 34 interposed therebetween. The first disk 32 is rotatably supported by the caliper body 12 by a bearing 35, and a cylindrical portion 36 that is inserted into the rotor 28 is integrally formed. A cylindrical sleeve 37 having a smaller diameter than the cylindrical portion 36 is integrally formed on the second disk 33, and the sleeve 37 is inserted into the cylindrical portion 36.
[0024]
For example, three ball grooves 38 and 39 each having an arc shape extending along the circumferential direction are formed on the opposing surfaces of the first disk 32 and the second disk 33 of the ball ramp mechanism 21. These ball grooves 38 and 39 are extended in the range of an equal central angle (for example, 90 °) and inclined in the same direction. Then, a ball 34 is inserted between the ball grooves 38 and 39 formed in the first and second disks 32 and 33, and the ball grooves 38 and 39 are moved by the relative rotation of the first and second disks 32 and 33. As the ball 34 rolls, the first disk 32 and the second disk 33 are relatively displaced in the axial direction. At this time, when the first disk 32 rotates counterclockwise with respect to the second disk 33, they are displaced in the direction of separating.
[0025]
A piston 40 is provided between the second disk 33 and the brake pad 14. The piston 40 has a cylindrical member 42a in which a screw portion 41 is formed on the outer periphery. The cylindrical member 42a is inserted into the sleeve 37 of the second disk 33 and is screwed into a screw portion 43 formed on the inner periphery thereof. In the cylindrical member 42a, a two-side chamfered portion (not shown) of the shaft 45 attached to the case 18 via the bracket 44 is fitted, and its rotation is restricted. Further, the piston 40 has a substantially disk-shaped pressing member 42b that is connected to the shaft 45 of the cylindrical member 42a in a state where the rotation is restricted to the opposite side. A thrust sensor (thrust detecting means) 46 for detecting a piston thrust received by the piston 40 is provided between the cylindrical member 42a, the pressing member 42b, and the shaft 45.
[0026]
The screw portion 41 of the cylindrical member 42 of the piston 40 and the screw portion 43 of the sleeve 37 of the second disk 33 form an irreversible screw, and the piston 40 moves even if a force acts in the axial direction. However, the second disk 33 is moved to the disk 11 side by rotating counterclockwise.
[0027]
A plurality of disc springs (compression springs) 49 are interposed between spring receivers 47 and 48 respectively formed on the outer peripheral portion of the shaft 45 and the inner peripheral portion of the sleeve 37 of the second disc 33, and the second disc is caused by the spring force. 33 is biased so as to sandwich the ball 34 with the first disk 32. The shaft 45 is attached to the bracket 44 by an adjustment screw 50 and a lock nut 51.
[0028]
A ring member 52 is fixed to the outer diameter portion of the second disk 33 closest to the disk 11. On the other hand, on the caliper main body 12 side of the claw portion 13, a cylindrical member 53 is provided in a fixed position on the inner side. Has been placed. A ring member 54 is fixed inside the cylindrical member 53 so as to face the ring member 52, and an appropriate resistance force is applied between the ring member 52 and the ring member 54. A wave washer 55 is interposed.
[0029]
A controller (control means) (not shown) is connected to the electric motor 19, the position detector 20, and the thrust sensor 46 via a connector 31, and this controller detects the detection result of the position detector 20, that is, the actual motor motor 19. By controlling the electric motor 19 based on the motor rotation position, the current value of the electric motor 19, and the detection result of the thrust sensor 46, that is, the actual piston thrust, control is performed so that the piston thrust becomes the target thrust.
[0030]
Next, the speed reduction mechanism 22 will be described. An eccentric shaft 57 is formed at one end of the mouth 58 of the electric motor 19, and an eccentric plate 59 is rotatably attached to the outer peripheral portion of the eccentric shaft 57 via a bearing 58. A fixed plate 60 is fixed to the caliper body 12 so as to face the eccentric plate 59. A plurality of holes (recesses) 61 and 62 are formed along the circumferential direction on the opposing surfaces of the eccentric plate 59 and the fixed plate 60, and a ball (steel ball) 63 is formed between these holes 61 and 62. An Oldham mechanism is formed by interposing, and an eccentric plate 59 that revolves is supported. One end surface of the eccentric plate 59 is opposed to the first disk 32, and cycloid grooves 64 and 65 are formed on these opposed surfaces, respectively, and a ball (steel ball) 66 is inserted between the cycloid grooves 64 and 65. Has been.
[0031]
A cylindrical spring holder 67 is attached to the outer periphery of the tip of the sleeve 37 of the second disk 33 so as not to rotate by a pin 68. One end portion of the spring holder 67 engages with the tip end portion of the cylindrical portion 36 of the first disk 32 to limit the relative rotation thereof to a certain range. A coil spring 69 is wound around the spring holder 67, and the coil spring 69 is twisted with a predetermined set load, one end of which is coupled to the spring holder 67, and the other end of the first disk 32. Coupled to the cylindrical portion 36.
[0032]
Next, the basic operation of the electric disc brake of the present embodiment configured as described above will be described.
[0033]
In the non-braking state, the ball 34 of the ball ramp mechanism 21 is at the deepest end of the ball grooves 38 and 39, and the first disk 32 and the second disk 33 are closest. The controller rotates the rotor 28 of the electric motor 19 clockwise when generating the braking force. Then, the eccentric plate 59 revolves, and the first disk 32 rotates counterclockwise with respect to the rotor 28 at a constant rotation ratio N expressed by the following equation by the action of the cycloid grooves 64 and 65 and the ball 66.
N = (d−D) / D
here,
d: Reference circular diameter of the cycloid groove 64
D: Reference circular diameter of cycloid groove 65
That is, the first disk 32 is decelerated with respect to the rotor 28 at a constant reduction ratio α (= 1 / N) and rotates counterclockwise, and the torque is amplified accordingly.
[0034]
The rotational force of the first disk 32 is transmitted to the second disk 33 via the coil spring 69. Before the piston 40 presses the brake pads 14 and 15, almost no axial load acts on the piston 40, and the resistance generated in the screw portions 41 and 43 between the piston 40 and the second disk 33 is small. The set load of the coil spring 69 causes the second disk 33 to rotate integrally with the first disk 32, causing relative rotation between the second disk 33 and the piston 40, and the piston 40 is moved by the action of the screw portions 41 and 43. Advance to the disk 11 side. Thereby, the screw portions 41 and 43 constitute a conversion mechanism portion that converts the rotational motion of the electric motor 19 into the linear motion of the piston 40.
[0035]
At the time of the forward movement, the ring member 52 fixed to the second disk 33 rotating integrally with the first disk 32 and the ring member 54 fixedly disposed on the claw portion 13 via the cylindrical member 53 are relatively rotated. Thus, the wave washer 55 interposed therebetween provides an appropriate resistance against the rotation of the second disk 33.
[0036]
Then, the piston 40 comes into contact with one brake pad 14 and presses it against the disk 11. The reaction force causes the caliper body 12 to move along the slide pin of the carrier 16, so that the claw portion 13 moves to the other brake pad. 15 is pressed against the disk 11.
[0037]
After both brake pads 14 and 15 are pressed against the disk 11, a large axial load acts on the piston 40 due to the reaction force, so that the resistance of the screw portions 41 and 43 increases and the set load of the coil spring 69 is increased. As a result, the second disk 33 stops rotating, and as a result, the coil spring 69 is bent and relative rotation occurs between the first disk 32 and the second disk 33 of the ball ramp mechanism 21. As a result, the ball 34 rolls in the ball grooves 38 and 39 to advance the second disk 33 and the piston 40 together (that is, linear movement), and the brake pads 14 and 15 are further pressed against the disk 11 by the piston 40. . Thereby, the ball ramp mechanism 21 also constitutes a conversion mechanism unit that converts the rotational motion of the electric motor 19 into the linear motion of the piston 40.
[0038]
Even after the piston 40 contacts the brake pad 14, the controller controls the current value of the electric motor 19 from the detection result of the position detector 20, that is, the motor rotational position, and the detection result of the thrust sensor 46, that is, the piston thrust. By doing so, the piston thrust is controlled to a desired value.
[0039]
Here, the controller obtains a braking force of the electric caliper 10 based on detection data from various sensors, that is, a target thrust to be generated in the piston 40, and applies a thrust to the electric motor 19 so that the target thrust is generated in the piston 40. Thrust control using the piston thrust detected by the sensor 46 as feedback and position control using the motor rotation position detected by the position detector 20 as feedback are performed.
[0040]
Then, the controller calculates the thrust sensor 46 from the change amount of the motor rotation position detected by the position detector 20 (change amount per unit time; hereinafter the same) and the change amount of the piston thrust detected by the thrust sensor 46. Specifically, the zero point of the piston thrust is detected when the electric motor 19 is rotated in the direction to open the pad clearance.
[0041]
In other words, the electric disc brake is affected by the built-in thrust sensor 46 due to frictional heat generated by braking during driving, heat generation of the electric motor, temperature change in the surrounding environment, etc., and so-called temperature drift occurs in which the output value changes. Resulting in.
[0042]
For example, FIG. 2 shows an example of the relationship between the actual thrust of the piston 40 and the output value of the thrust sensor 46 when the thrust sensor 46 drifts in temperature. Thus, even if the actual thrust becomes zero, an output value of the thrust sensor 46, that is, a state in which the value F0 in which the piston thrust exceeds zero is detected, and this value F0 is the temperature drift value.
[0043]
3 shows a direction in which the brake pads 14 and 15 are separated from the disk 11 from the state in which the brake pads 14 and 15 are in contact with the disk 11 when such a temperature drift is generated in the thrust sensor 46. That is, when the electric motor 19 is rotated so as to move the piston 40 in the direction of opening the pad clearance (FIG. 3A) and the output value of the thrust sensor 46 (FIG. 3B). Although the series data is shown, as shown in FIG. 3, the piston thrust, which is the output value of the thrust sensor 46, is the value F0 and the amount of change is notwithstanding that the amount of change of the motor rotational position has occurred. A state of zero (after T1 in FIG. 3) will occur, and when the amount of change in piston thrust is zero, the actual thrust is zero.
[0044]
Therefore, the controller starts from the state in which the brake pads 14 and 15 are in contact with the disk 11 and the thrust sensor 46 detects a piston thrust of a predetermined value or more that can eliminate the influence of the temperature drift. , 15 are separated, that is, when the electric motor 19 is rotated so as to move the piston 40 in the direction in which the pad clearance is opened, the piston thrust changes in a state where the change amount of the motor rotational position is not zero. The piston thrust F0 at the switching point T1 when the amount is switched from non-zero to zero is detected as a temperature drift value of the thrust sensor 46. Then, the temperature drift value is subtracted to correct the piston thrust in the thrust sensor 46 to the zero point.
[0045]
The controller executes such zero correction of the piston thrust each time the piston 40 is moved in the direction of opening the pad clearance from the state in which the piston thrust greater than the predetermined value is detected by the thrust sensor 46. .
[0046]
On the other hand, when the controller rotates the electric motor 19 in the direction of reducing the pad clearance from the change amount of the motor rotational position detected by the position detector 20 and the change amount of the piston thrust detected by the thrust sensor 46. In addition, the zero point of the piston thrust in the thrust sensor 46 is detected. At the same time, the controller generates a piston thrust from the change amount of the motor rotational position detected by the position detector 20 and the change amount of the piston thrust detected by the thrust sensor 46 (generation of the piston thrust is started). ) The motor rotation position is detected. Specifically, when the electric motor 19 is rotated in the direction in which the pad clearance is reduced, the motor rotation position at which the piston thrust is generated is detected.
[0047]
The controller moves the brake pads 14 and 15 in the direction of the disk 11 from a standby state in which the brake pads 14 and 15 are separated from the disk 11 during an operation that is predicted to be performed such as an accelerator off. In other words, the electric motor 19 is controlled to rotate so as to move the piston 40 in the direction in which the pad clearance is reduced. FIG. 4 shows that when such control is performed, the temperature drift as described above is thrust. The time-series data of the motor rotation position (FIG. 4 (a)) and the output value (FIG. 4 (b)) of the thrust sensor 46 when occurring in the sensor 46 are shown. As shown in FIG. 4, while the change amount of the motor rotational position is occurring, the change amount of the piston thrust, which is the output value of the thrust sensor 46, is zero, and the change amount of the piston thrust is zero. It will be switched to a state that is not.
[0048]
Therefore, the controller moves the piston 40 from the standby state in which the brake pads 14 and 15 are separated from the disk 11 to the direction in which the disk 11 is brought close to the brake pads 14 and 15, that is, the direction in which the pad clearance is reduced. When the electric motor 19 is rotated, the piston thrust F0 at the switching point T1 when the change amount of the piston thrust is changed from the zero state to the non-zero state in the state where the change amount of the motor rotation position is not zero. Is detected as a temperature drift value of the thrust sensor 46. Then, the temperature drift value is subtracted to correct the piston thrust in the thrust sensor 46 to the zero point.
[0049]
At the same time, when the change amount of the piston thrust is changed from the zero state to the non-zero state, the controller moves the electric motor 19 to the motor rotation position X0 ′ that generates the piston thrust F0 ′ that is not noticed by the driver. After the rotation, the motor rotational position X0 at the time T1 when the change amount of the piston thrust is changed from the zero state to the non-zero state, that is, the motor rotational position X0 is generated (piston thrust generation is started). On the other hand, the electric motor 19 is returned by a predetermined rotation amount added with a minimum amount that makes the thrust almost zero. As a result, the pad clearance can be made zero without generating piston thrust in a state where execution of a brake operation such as accelerator-off is predicted.
[0050]
The controller executes the zero correction of the piston thrust and the detection of the motor rotation position at which the piston thrust occurs as described above every time the piston 40 is moved in the direction of reducing the pad clearance from the standby state.
[0051]
A control program including the above is stored in the controller.
[0052]
The controller is controlled according to the flowchart schematically shown in FIG. 5. First, the pad clearance is managed (step S1), and it is determined whether or not the pad clearance is opened to enter a standby state. (Step S2). Here, when the vehicle is running and the brake is not depressed, it is determined that the pad clearance is to be opened, and control for opening the pad clearance is performed (step S3).
[0053]
In the control of opening the pad clearance in step S3, the electric motor 19 is rotated in the opening direction at a constant speed, the motor rotation position detected by the position detector 20 at this time, and the piston thrust detected by the thrust sensor 46 Are monitored, and each change amount is calculated. Then, correction is made so that the piston thrust at the time when the change in the piston thrust ceases when there is a change in the motor rotation position, and the pad at which the piston thrust is zero and the pad clearance is zero at this time Recognize as a contact position. Then, the specified amount electric motor 19 is returned from the pad contact position to complete the operation of opening the pad clearance.
[0054]
If it is not determined in step S2 that the pad clearance is to be opened, it is determined whether or not the pad clearance is closed from the standby state (step S4). Here, when the vehicle is running and the brake is not depressed and the accelerator is further released, it is determined that the pad clearance is closed, and control for closing the pad clearance is performed (step S5).
[0055]
In the control for closing the pad clearance in step S5, the electric motor 19 is rotated in the closing direction at a constant speed, the motor rotation position detected by the position detector 20 at this time, and the piston thrust detected by the thrust sensor 46 Are monitored, and each change amount is calculated. Then, correction is made so that the piston thrust at the time when the change in piston thrust occurs in a state where there is a change in the motor rotation position, and the motor rotation position at this point is zero when the piston thrust is zero and the pad clearance is zero. Recognized as a pad contact position. Since a small piston thrust is generated at this pad contact position, the electric motor 19 is returned by the minimum amount added to the pad contact position to make this thrust almost zero, and the pad clearance is closed. Complete.
[0056]
According to the electric disk brake and its control program of the present embodiment described above, the zero point of the piston thrust in the thrust sensor 46 is detected from the amount of change in the motor rotational position and the amount of change in the piston thrust. In order to perform point correction, it is not necessary to retreat the piston 40 beyond the set position. Therefore, since the zero point of the piston thrust can be detected even during traveling, it is possible to eliminate the influence of temperature drift that has occurred during traveling.
[0057]
Therefore, the piston thrust can be controlled appropriately.
[0058]
In addition, when the electric motor 19 is rotated in the direction of opening the pad clearance or in the direction of closing the pad clearance, the zero point of the piston thrust is detected. The zero point of the piston thrust is detected at the position where the amount changes from the state where it disappears, or the position where the piston thrust changes from the state where there is no change in the piston thrust even though there is a change in the motor rotation position. The zero point of the piston thrust can be detected.
[0059]
Furthermore, since the motor rotation position where the piston thrust is generated is detected from the change amount of the motor rotation position and the change amount of the piston thrust, it is not necessary to retreat the piston 40 beyond the set position in this respect as well. Therefore, since it is possible to detect the motor rotation position at which the piston thrust is generated even during traveling, it is possible to eliminate the influence of temperature drift occurring during traveling.
[0060]
Accordingly, since the pad clearance amount can be controlled appropriately, drag between the disk 11 and the brake pads 14 and 15 can be prevented, and the life of the brake pads 14 and 15 can be extended.
[0061]
In addition, when the electric motor is rotated in the direction to reduce the pad clearance, the motor rotation position at which the piston thrust is generated is detected. The motor rotational position where the piston thrust is generated can be detected.
[0062]
Therefore, the response of the brake can be improved.
[0063]
【The invention's effect】
As described above in detail, according to the electric disk brake of the first aspect of the present invention, the control means determines that the piston thrust of the thrust detecting means is zero based on the change amount of the motor rotational position and the change amount of the piston thrust. Since the point is detected, it is not necessary to retreat the piston beyond the set position in order to perform the zero point correction. Therefore, since the zero point of the piston thrust can be detected even during traveling, it is possible to eliminate the influence of temperature drift that has occurred during traveling.
[0064]
Therefore, the piston thrust can be controlled appropriately.
[0065]
Also, when the vehicle is running and the accelerator is released, rotate the electric motor in the direction to close the pad clearance. Close pad clearance In that case, zero point of piston thrust correction Therefore, for example, the zero point of the piston thrust is set at a position where there is a change amount of the motor rotation position and the state where the change amount of the piston thrust is not changed to a state where the change occurs. correction can do.
[0066]
According to the electric disk brake of claim 2 of the present invention, the control means rotates the electric motor in a direction to close the pad clearance when the vehicle is running and the accelerator is released. Close pad clearance Since the motor rotation position where the piston thrust is generated is detected from the change amount of the motor rotation position and the change amount of the piston thrust, it is not necessary to retreat the piston beyond the set position. Therefore, since it is possible to detect the motor rotation position at which the piston thrust is generated even during traveling, it is possible to eliminate the influence of temperature drift occurring during traveling.
[0067]
Therefore, since the pad clearance amount can be controlled appropriately, drag between the disc and the brake pad can be prevented and the life of the brake pad can be extended.
[0068]
In addition, when the vehicle is running and the accelerator is released, that is, when the brake operation is predicted, the electric motor is rotated in the direction to close the pad clearance. Close pad clearance In this case, since the motor rotation position at which the piston thrust is generated is detected, the motor rotation position at which the piston thrust is generated can be detected every time the pad clearance is reduced.
[0069]
Therefore, the response of the brake can be improved.
[0070]
According to the electric disk brake control program of claim 4 of the present invention, the zero point of the piston thrust in the thrust detecting means is determined from the amount of change in the motor rotational position and the amount of change in the piston thrust. correction Therefore, it is not necessary to retreat the piston beyond the set position in order to perform the zero point correction. Therefore, the zero point of piston thrust is correction Therefore, it is possible to eliminate the influence of temperature drift that occurs during traveling.
Also, when the vehicle is running and the accelerator is released, rotate the electric motor in the direction to close the pad clearance. Close pad clearance In that case, zero point of piston thrust correction Therefore, for example, the zero point of the piston thrust is set at a position where there is a change amount of the motor rotation position but the state where there is no change amount of the piston thrust is changed to a generated state. correction can do.
[0071]
Therefore, the piston thrust can be controlled appropriately.
[0072]
According to the control program for the electric disk brake of the fifth aspect of the present invention, the piston is installed at the installation position in order to detect the motor rotation position where the piston thrust is generated from the change amount of the motor rotation position and the change amount of the piston thrust. There is no need to retreat. Therefore, since it is possible to detect the motor rotation position at which the piston thrust is generated even during traveling, it is possible to eliminate the influence of temperature drift occurring during traveling.
In addition, when the vehicle is running and the accelerator is released, that is, when the brake operation is predicted, the electric motor is rotated in the direction to close the pad clearance. Close pad clearance In this case, since the motor rotation position at which the piston thrust is generated is detected, the motor rotation position at which the piston thrust is generated can be detected every time the pad clearance is reduced.
[0073]
Therefore, since the pad clearance amount can be controlled appropriately, drag between the disc and the brake pad can be prevented and the life of the brake pad can be extended.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an electric caliper of an electric disc brake according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining a state of temperature drift of a thrust sensor, and shows a relationship between an actual thrust (horizontal axis) and an output value (vertical axis) of the thrust sensor.
FIGS. 3A and 3B are diagrams showing time-series data when the pad clearance of the electric disc brake according to the embodiment of the present invention is opened, in which FIG. 3A shows the motor rotation position, and FIG. It is shown.
FIGS. 4A and 4B are diagrams showing time-series data when the pad clearance of the electric disc brake according to the embodiment of the present invention is closed, in which FIG. 4A shows the motor rotation position, and FIG. 4B shows the output value of the thrust sensor; It is shown.
FIG. 5 is a flowchart schematically showing a main part of control contents of the controller of the electric disc brake according to the embodiment of the present invention.
[Explanation of symbols]
10 Electric caliper
11 discs
14,15 Brake pads
19 Electric motor
20 position detector (position detecting means)
21 Ball ramp mechanism (conversion mechanism)
40 piston
41, 43 Screw part (conversion mechanism part)
46 Thrust sensor (thrust detection means)

Claims (6)

An electric motor;
A conversion mechanism for converting the rotational motion of the electric motor into linear motion of a piston and bringing the brake pad into contact with the disc with the piston;
Position detecting means for detecting a motor rotation position of the electric motor;
Thrust detecting means for detecting piston thrust received by the piston;
Control means for controlling the electric motor to generate a target thrust in the piston by thrust control based on the piston thrust detected by the thrust detection means and position control based on the motor rotational position detected by the position detection means. An electric disc brake having
It said control means vehicle by rotating the electric motor in a direction to pack the pad clearance when the accelerator is running is released by closing the pad clearance, while the the motor rotational position is changing The piston thrust value when the change amount of the piston thrust changes from the zero state to the non-zero state is detected, and the piston thrust value is subtracted to obtain the zero point of the piston thrust in the thrust detecting means. Electric disc brake characterized by correcting . An electric motor;
A conversion mechanism for converting the rotational motion of the electric motor into linear motion of a piston and bringing the brake pad into contact with the disc with the piston;
Position detecting means for detecting a motor rotation position of the electric motor;
Thrust detecting means for detecting piston thrust received by the piston;
Control means for controlling the electric motor to generate a target thrust in the piston by thrust control based on the piston thrust detected by the thrust detection means and position control based on the motor rotational position detected by the position detection means. An electric disc brake having
It said control means vehicle by rotating the electric motor in a direction to pack the pad clearance when the accelerator is running is released by closing the pad clearance, while the the motor rotational position is changing The electric disc brake detects the motor rotation position when the change amount of the piston thrust is changed from a zero state to a non-zero state . After the correction of the zero point of the piston thrust or the detection of the rotational position of the motor when the change amount of the piston thrust is changed from the zero state to the non-zero state , the pad is set so that the piston thrust is almost zero. The electric disc brake according to claim 1 or 2, wherein the electric motor is returned in a direction to open a clearance. An electric motor;
A conversion mechanism for converting the rotational motion of the electric motor into linear motion of a piston and bringing the brake pad into contact with the disc with the piston;
Position detecting means for detecting a motor rotation position of the electric motor;
Thrust detecting means for detecting piston thrust received by the piston;
Control means for controlling the electric motor to generate a target thrust in the piston by thrust control based on the piston thrust detected by the thrust detection means and position control based on the motor rotational position detected by the position detection means. An electric disc brake control program comprising:
When the vehicle is running and the accelerator is released, the electric motor is rotated in a direction to close the pad clearance to close the pad clearance, and the piston thrust is changed while the motor rotation position is changing. A piston thrust value when the change amount is switched from a zero state to a non-zero state is detected, and the piston thrust value is subtracted to correct the zero point of the piston thrust in the thrust detecting means. Electric disc brake control program. An electric motor;
A conversion mechanism for converting the rotational motion of the electric motor into linear motion of a piston and bringing the brake pad into contact with the disc with the piston;
Position detecting means for detecting a motor rotation position of the electric motor;
Thrust detecting means for detecting piston thrust received by the piston;
Control means for controlling the electric motor to generate a target thrust in the piston by thrust control based on the piston thrust detected by the thrust detection means and position control based on the motor rotational position detected by the position detection means. An electric disc brake control program comprising:
When the vehicle is running and the accelerator is released, the electric motor is rotated in a direction to close the pad clearance to close the pad clearance, and the piston thrust is changed while the motor rotation position is changing. An electric disk brake control program for detecting the motor rotation position when the change amount is switched from a zero state to a non-zero state . After the correction of the zero point of the piston thrust or the detection of the rotational position of the motor when the change amount of the piston thrust is changed from the zero state to the non-zero state , the pad is set so that the piston thrust is almost zero. 6. The electric disk brake control program according to claim 4, wherein the electric motor is returned in a direction to open the clearance.

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