JP2018058530A - Electric-brake control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric brake device with a novel technique to meet a requirement to detect whether a return spring for retracting a piston is normally operating.SOLUTION: A piston strokes toward a brake pad from a point O in association with a motor rotating toward a first rotational direction. A stroke amount Sa is a stoke amount S of the piston when the piston is pressed to the brake pad. The graph shows relations between the stroke amount S and its corresponding current value I, with a solid line representing that a coil spring is normal while a dotted line representing that the coil spring is abnormal. When the coil spring is abnormal, the current value I corresponding to the stroke amount is smaller than with the coil spring normal. Therefore, an electric-brake control apparatus is capable of determining whether the coil spring is normal on the basis of a desired stroke amount S from the point O to the stroke amount Sa and the current value I.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electric brake control device used in an electric brake device for a vehicle.

  2. Description of the Related Art An electric brake device for a vehicle is known in which a piston that presses a braking member is advanced by rotation of a motor by an electric current controlled by the electric brake control device. In the electric brake device controlled in this way, a return spring for retracting the piston may be provided. For example, Patent Literature 1 discloses an electric brake device having a return spring that assists the rotation of the motor when the operation of the electric brake device is released.

JP2013-24389A

  In the electric brake device as described above, if the piston is not sufficiently retracted and a running resistance is generated, the fuel consumption is deteriorated. Therefore, it is necessary to detect whether or not the return spring for retracting the piston is operating normally.

  An object of the present invention is to provide an electric brake control device capable of detecting the state of a return spring for retracting a piston.

  In order to solve the above-described problem, in the present invention, an energization state-related amount indicating an energization state of a motor that moves the piston in a direction in which the piston is pressed against the pad by rotation of the motor output shaft in the first rotation direction is acquired. An acquisition unit; and a spring that accumulates elastic energy by rotation of the motor output shaft in the first rotation direction, wherein the motor output shaft is in a direction opposite to the first rotation direction by releasing the elastic energy. An abnormality detection unit that detects an abnormality of a piston return spring that rotates in two rotation directions, wherein the abnormality detection unit has an axial force applied to the pad when the piston is pressed against the pad. An abnormality of the piston return spring is detected on the basis of the energized state relation amount acquired by the acquisition unit until it is exerted. Electric brake control device can be realized, characterized in that those.

With the above configuration, when the motor output shaft rotates in the first rotation direction, the piston return spring accumulates the elastic energy. At this time, a force that is rotated in the first rotation direction by the motor and a force that is rotated in the second rotation direction by the return spring are exerted on the motor output shaft.
Accordingly, when the piston return spring is normal and abnormal, the force that rotates the motor output shaft in the second rotational direction is different, and therefore the piston is pressed against the pad and the axial force is applied to the pad. The energization state-related quantities of the motors obtained up to when they are applied are different. Therefore, the abnormality of the piston return spring can be detected based on the energized state related quantity of the motor.

  Further, in the electric brake control device, the energization state-related amount is an amount related to a current value supplied to the motor, and the abnormality detection unit detects the piston from the first position to the first position. An abnormality of the piston return spring may be detected when an increasing gradient of the current value with respect to the movement amount of the piston when moving to a second position close to the pad is equal to or less than a set value.

  Further, the energized state related amount is an amount related to the amount of electric power supplied to the motor, and the abnormality detecting unit detects that the piston is at the pad from the position where the distance between the piston and the pad is maximized. An abnormality of the piston return spring is detected when the amount of electric power necessary to move the piston to a position where the axial force is exerted on the pad by being pressed against the pad is equal to or less than a set value. it can.

  It is possible to detect whether or not the return spring is normal by acquiring the energization state related amount of the piston.

It is a mimetic diagram showing the whole brake system composition to which the electric brake control device of a 1st embodiment was applied. It is sectional drawing of the electric brake device of 1st Embodiment. It is a figure which shows the relationship between the electric current value supplied to the motor of the electric brake device of 1st Embodiment, and the stroke amount of a piston. It is a flowchart which shows the state detection process of the spiral spring which the electric brake control apparatus of 1st Embodiment performs. It is a figure which shows the electric energy supplied to the motor of the electric brake device of 2nd Embodiment. It is a flowchart which shows the state detection process of the spiral spring which the electric brake control apparatus of 2nd Embodiment performs.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing the overall configuration of an electric brake system 2 to which the electric brake control device 10 of the first embodiment of the present invention is applied.
As shown in FIG. 1, the electric brake system 2 includes a brake pedal (not shown), a stroke sensor 6, a brake switch 7, a battery 8, an electric brake control device 10, and an electric brake device 12. The electric brake device 12 is provided on each wheel of the vehicle. Electric brake devices 12FR, 12FL, 12RR, and 12RL are provided on the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel of the vehicle, respectively. Since each of the electric brake devices 12FR, 12FL, 12RR, and 12RL has the same configuration, the electric brake device 12FR will be described here.

The stroke sensor 6 detects the stroke amount of the brake pedal. The brake switch 7 detects that the brake pedal has been depressed, and is turned on when the brake pedal is depressed. The battery 8 is connected to the electric brake control device 10 and the electric brake device 12. The electric brake control device 10 includes a control unit 13. The control unit 13 includes a CPU, a ROM, a RAM, a communication interface, and the like, and performs various controls by executing a program recorded in the ROM on the CPU.
The control unit 13 is connected to the stroke sensor 6, the drive circuit 14, the current detection unit 15, the resolver 50, and the load sensor 86. Details of the resolver 50 and the load sensor 86 will be described later. A motor 32 (described later) is connected to the drive circuit 14, and the drive circuit 14 outputs a current to the motor 32 based on a command transmitted from the control unit 13. The current supplied to the motor 32 is detected by the current detector 15.

FIG. 2 is a cross-sectional view of the electric brake device 12FR when cut along a horizontal plane. In FIG. 2, the front-rear direction of the vehicle is defined with reference to the traveling direction of the vehicle, and the left-right direction is defined in correspondence with the vehicle width direction of the vehicle.
As shown in FIG. 2, the electric brake device 12 includes a caliper 16, a pair of brake pads 18 held by the caliper 16, and a piston drive device 20. The caliper 16 is provided with a slider 22 that is a cylindrical member having an axis parallel to the left-right direction. A pair of guide pins 24 fixed to the vehicle body side (wheel side) are inserted into the inner peripheral portions of the sliders 22 respectively. The pair of guide pins 24 are parallel to the left-right direction, and the slider 22 is formed to be slidable with respect to the outer peripheral surface of the pair of guide pins 24. That is, the caliper 16 is attached so as to be movable in the left-right direction with respect to the vehicle body.
The pair of brake pads 18 are held by the caliper 16 and sandwich the brake rotor 26 that rotates together with the wheels from the left and right directions.

The piston drive device 20 includes a housing 30, a motor 32, a linear motion conversion mechanism 34, a piston 36, and a spiral spring 38. The housing 30 is fixed to the inner periphery of the caliper 16. The motor 32 is disposed on the inner periphery of the housing 30. The motor 32 includes a plurality of coils 40 arranged in the circumferential direction on the inner peripheral surface of the housing 30 and a rotor 42 provided inside the coils 40. The rotor 42 is a cylindrical member, and is arranged such that an axis L that is the central axis of the rotor 42 is parallel to the left-right direction.
The rotor 42 is rotatably supported with respect to the housing 30 by a bearing 46 provided at the left end portion of the housing 30. A plurality of grooves 44 are formed on the inner peripheral surface of the lower end portion of the rotor 42, and the plurality of grooves 44 engage with a plurality of protrusions 64 included in a flange portion 62 described later. A plurality of magnets 48 facing the plurality of coils 40 are arranged on the outer peripheral surface of the rotor 42 in the circumferential direction. In the motor 32, since the rotor 42 and the magnet 48 function as a rotor, the rotor 42 rotates around the axis L. The rotation angle of the rotor 42 is detected by a resolver 50 fixed to the inner peripheral surface of the housing 30.

The linear motion conversion mechanism 34 converts the rotational motion of the motor 32 into the linear motion of the piston 36. The linear motion conversion mechanism 34 is provided on the inner peripheral portion of the rotor 42 of the motor 32 and includes an output cylinder 52, an input shaft 54, and a plurality of planetary rollers 56.
The output cylinder 52 is provided on the inner peripheral portion of the rotor 42 so that the axis coincides with the axis L. Since the outer peripheral surface of the output cylinder 52 is supported by the support portion 58, the output cylinder 52 is supported so as to be slidable in the left-right direction with respect to the housing 30. The support portion 58 is formed in an annular shape and is fixed to the inner peripheral surface of the housing 30. A space between the inner peripheral portion of the support portion 58 and the output cylinder 52 is sealed with a seal member.
The input shaft 54 is disposed on the inner peripheral portion of the output cylinder 52 and is supported by the bearing 46 so as to be rotatable around the axis L with respect to the housing 30. A plurality of planetary rollers 56 are disposed between the input shaft 54 and the output cylinder 52. The plurality of planetary rollers 56 are rotatably supported by a carrier (not shown) supported by the output cylinder 52.

A piston 36 is fitted into the inner peripheral portion of the right end portion of the output cylinder 52, and the output cylinder 52 and the piston 36 move integrally. Therefore, the piston 36 can move in the left-right direction with respect to the housing 30. When the piston 36 moves to the right, the piston 36 approaches the brake pad 18, and when the piston 36 moves to the left, the piston 36 moves away from the brake pad 18.
The input shaft 54 is disposed so that the rotation axis coincides with the axis L, and includes a shaft portion 60 disposed inside the output cylinder 52 and a flange portion 62 fixed to the left end of the shaft portion 60. On the outer peripheral surface of the flange portion 62, a plurality of protrusions 64 parallel to the left-right direction are formed at positions corresponding to the plurality of grooves 44 on the inner peripheral surface of the opposed rotor 42. The plurality of protrusions 64 enter and engage with the plurality of grooves 44. Therefore, the flange portion 62 rotates as the rotor 42 rotates. A spring winding shaft 66 is fixed to the left side surface of the flange portion 62 so as to be parallel to the left-right direction. A spiral spring 38 is disposed around the spring winding shaft 66. Details of the spiral spring 38 will be described later. A retaining member fixed to the inner peripheral surface of the rotor 42 abuts on the right side surface of the flange portion 62, and the rightward movement of the input shaft 54 relative to the rotor 42 is restricted.

The output cylinder 52, the input shaft 54, and the plurality of planetary rollers 56 are each formed with a helical gear portion and a screw gear mechanism 68 and a helical gear mechanism 70 along the axis L. Has been. An output screw portion 72 formed on the left side of the inner peripheral portion of the output cylinder 52, an input screw portion 74 formed on the left side of the outer peripheral portion of the input shaft 54, and a left side of the outer peripheral portions of the plurality of planetary rollers 56 The formed planetary screw portions 76 are screwed together to form a screw gear mechanism 68. The output helical gear portion 78 formed between the output screw portion 72 and the right end of the output cylinder 52, the input helical gear portion 80 formed at the right end portion of the input shaft 54, and the right ends of the plurality of planetary rollers 56 are formed. The planetary helical gear portion 82 formed in the portion meshes with each other to constitute a helical gear mechanism 70.
The number of threads of the screw gear mechanism 68 and the number of teeth of the helical gear mechanism 70 are defined as shown in Table 1 below.

The screw gear mechanism 68 and the helical gear mechanism 70 are formed so as to satisfy the following expressions 1 and 2.
Zns / Zps = Zn / Zp (1)
Zss / Zps ≠ Zs / Zp (2)
In the linear motion conversion mechanism 34 according to the present embodiment, as shown in Equation 2, the ratio of the number Zss of the input screw portion 74 and the number Zps of the planetary screw portion 76 is the number of teeth Zs of the helical gear portion 80. Is different from the ratio of the number of teeth Zp of the helical gear portion 82, and the ratio of the number Zns of the output screw portion 72 and the number Zps of the planetary screw portion 76 as shown in Equation 1 is The number of teeth Zn of the gear portion 78 and the planetary gear are equal to the ratio of the number of teeth Zp of the helical gear portion 82.
When the input shaft 54 rotates, a difference in rotation angle between the input screw portion 74 and the planetary screw portion 76 and between the input helical gear portion 80 and the planetary helical gear portion 82 tends to occur. However, since the screw and helical gears of the input shaft 54 and the plurality of planetary rollers 56 are integral with each other, the difference between the rotation angles does not occur, and the output cylinder 52 and the plurality of planets 56 are so absorbed. The planetary roller 56 is displaced in the axial direction with respect to the input shaft 54. At this time, the plurality of planetary rollers 56 do not move relative to the output cylinder 52 in the axial direction. The details of the linear motion conversion mechanism 34 are described in Japanese Patent No. 4186969.

This mechanism has a planetary roller type speed reduction mechanism, and a large gear ratio can be obtained. Therefore, a small motor with low torque can be adopted as the motor. On the other hand, since the reverse efficiency is low, a spiral spring 38 for moving the piston 36 away from the brake pad 18 is provided.
As shown in FIG. 2, the spiral spring 38 is provided in the hollow portion 84 of the washer on the housing side of the bearing 46. The inner end of the spiral spring 38 is fixed to the spring winding shaft 66, and the outer end is fixed to the inner peripheral surface of the hollow portion 84. The spiral spring 38 accumulates elastic energy as the spring winding shaft 66 rotates in the first rotation direction, and increases the elastic energy. Further, the spiral spring 38 reduces (releases) the accumulated elastic energy by rotating the spring winding shaft 66 in the second rotation direction from the state where the elastic energy is accumulated.

  The load sensor 86 is provided on the inner surface of the left end of the housing 30. A part of the load sensor 86 is disposed so as to be positioned between the bearing 46 and the housing 30. When the piston 36 is pressed against the brake pad 18, the reaction force exerted from the brake pad 18 to the piston 36 is transmitted to the load sensor 86 via the input shaft 54 and the bearing 46. Therefore, the braking force of the electric brake device 12 can be detected based on the value of the load sensor 86 when the brake pad 18 is pressed against the brake rotor 26. Examples of the load sensor 86 include a strain gauge that detects a deformation amount of the inner surface of the left end of the housing 30 when a force is applied from the bearing 46 to the inner surface of the left end of the housing 30 as a load.

<Operation of electric brake device 12>
When the brake pedal is depressed, the motor 32 is driven by the electric brake control device 10, and the rotor 42 rotates in the first rotation direction that is the rotation direction when the piston 36 is moved in the direction approaching the brake pad 18. When the rotor 42 rotates, a force in the rotation direction is transmitted to the flange portion 62, and the input shaft 54 rotates in the first rotation direction. As a result, the plurality of planetary rollers 56 rotate, and the plurality of planetary rollers 56 and the output cylinder 52 move toward the brake pad 18 by the screw gear mechanism 68 and the helical gear mechanism 70. Further, the spiral spring 38 is wound around the spring winding shaft 66 by the rotation of the input shaft 54 in the first rotation direction. As a result, the spiral spring 38 accumulates elastic energy that attempts to rotate the input shaft 54 in the second rotation direction that is opposite to the first rotation direction.
The piston 36 moves toward the brake pad 18 integrally with the output cylinder 52 and is pressed against the brake pad 18. When the axial force of the piston 36 is exerted on the brake pad 18, the brake pad 18 moves toward the brake rotor 26, and when the brake pad 18 presses the brake rotor 26, the rotation of the wheel is braked.

  Thereafter, when the brake pedal is returned, the electric brake control device 10 rotates the rotor 42 in the second rotation direction. At this time, the elastic energy accumulated in the spiral spring 38 is released, and the spiral spring 38 applies a force in the second rotational direction to the spring winding shaft 66. When the spiral spring 38 applies a force in the second rotational direction, the output cylinder 52 and the plurality of planetary rollers 56 move in a direction away from the brake pad 18. When the piston 36 moves in a direction away from the brake pad 18 together with the output cylinder 52, and the piston 36 is released from the brake pad 18, the braking of the wheel rotation is released.

<Detection of state of spiral spring 38 based on current value I>
FIG. 3 is a diagram showing the relationship between the stroke amount S of the piston 36 and the current value I supplied to the motor 32. A point O in FIG. 3 indicates a position where the piston 36 is separated from the brake pad 18 and the piston 36 can move a certain distance toward the brake pad 18. The stroke amount S indicates the distance moved from the point O where the piston 36 starts to move toward the brake pad 18. The stroke amount S of the piston 36 when the piston 36 moves toward the brake pad 18 and hits the brake pad 18 is the stroke amount Sa. The solid line A shows the relationship between the stroke amount S and the current value I when the spiral spring 38 is normal, and the alternate long and short dash line B shows the stroke amount S and current when the spiral spring 38 is in an abnormal state such as plastic deformation or dropout. The relationship of value I is shown.
When an abnormality occurs in the spiral spring 38, the elastic energy accumulated when the spiral spring 38 is wound in the first rotation direction becomes smaller than normal. That is, since the force for rotating the spring winding shaft 66 in the second rotation direction is smaller than that in the normal state, the current value I with respect to the stroke amount S is smaller than that in the normal state. Therefore, the relationship between the stroke amount S and the current value I between the point O and the stroke amount Sa is represented by a one-dot chain line B having a smaller slope than the solid line A in FIG.

When the stroke amount S becomes larger than the stroke amount Sa, a reaction force is exerted on the piston 36 from the brake pad 18. Since the magnitude of the elastic energy of the spiral spring 38 is extremely smaller than the magnitude of the reaction force, it hardly affects the inclination of the straight line.
As described above, the electric brake control device 10 determines whether or not the spiral spring 38 is normal based on the current value I until the piston 36 is pressed against the brake pad 18 and the axial force is applied to the brake pad 18. .
The point O indicates the position of the piston 36 where the piston 36 is separated from the brake pad 18, and does not necessarily indicate the position of the piston 36 where the distance between the piston 36 and the brake pad 18 is maximum. is not.

FIG. 4 is a flowchart showing the state detection process of the spiral spring 38 executed in the electric brake control device 10. This process is started, for example, when the occupant is not operating the brake pedal and when a predetermined period has elapsed since the end of the operation of the brake pedal. The electric brake control device 10 returns the piston 36 to the start position in step 1 (hereinafter abbreviated as “S1”, and the same applies to other steps). The start position is a position where the piston 36 is separated from the brake pad 18 and the piston 36 can move a certain distance toward the brake pad 18 and corresponds to the point O in FIG.
Next, in S3, the electric brake control device 10 resets the stroke amount S of the piston 36 to zero. In S5, the electric brake control device 10 determines whether the brake pedal is depressed and the signal of the brake switch 7 (not shown) becomes an ON signal. When the signal of the brake switch 7 is not an ON signal, the process proceeds to S7, and when it is an ON signal, the state detection process based on the flow is terminated.

In S <b> 7, the electric brake control device 10 supplies the motor 32 with a current having a first current value that is a preset current value I. Next, the electric brake control device 10 integrates the rotation angle from when the motor 32 moves the piston 36 from the point O to the current time based on the signal received from the resolver 50. The electric brake control device 10 adds the stroke amount S of the piston 36 per unit amount of the rotation angle set in advance to the calculated rotation angle value, so that the stroke amount from the point O of the piston 36 to the present time is integrated. S is calculated. If the stroke amount S to date has not reached the first stroke S ₁ with respect to predetermined first current value, is further supplied current to the motor 32, the stroke amount S to date is the first stroke amount S current value I ₁ when reached ₁ is stored.

In S9, the electric brake control device 10 determines whether or not the number of current values I stored in S7 has reached a set number. The number of current values I stored in S7 is set in consideration of sensor variations and the like. For example, when the number of set current values I is 3, the electric brake control device 10 determines whether or not these three current values I are stored. When three current values I are stored, the process proceeds to S13, and when three current values I are not stored, the process returns to S7.
Electrically powered brake control unit 10, at S7, the current value I supplied to the motor 32 is increased gradually from the current the current value I ₁ until reaching the second stroke S _2. When the stroke amount S reaches the second stroke S _2, the current value I ₂ is stored, the process proceeds to S9. Processing from S7 S9 are repeated until the current value _{I 3} is stored.

In S11, the electric brake control device 10 calculates the slope of the current value I with respect to the stroke amount S using the _three current values I ₁ , I ₂ , and I ₃ stored in S7. Next, in S13, the electric brake control unit 10, a current value _{I 1,} I 2, a set value that is set as the slope of _{I 3} with respect to the stroke amount _{S 1,} S 2, _{S 3} when the spiral spring 38 is normal And whether or not the difference between the calculated slope value calculated in S11 is larger than a threshold value. When the difference between the set value and the calculated value is smaller than the threshold value, it is determined that the spiral spring 38 is normal, and the state detection process based on the flow is ended. If the difference between the set value and the calculated value is larger than the threshold value, it is determined that the spiral spring 38 is abnormal, a warning is issued in S15, and the state detection process based on the flow is terminated.

As described above, in this embodiment, when the input shaft 54 rotates in the first rotation direction, the spiral spring 38 accumulates elastic energy, and the spiral spring 38 rotates the input shaft 54 in the second rotation direction. Is exerted on the input shaft 54. Therefore, when the force to rotate the input shaft 54 of the spiral spring 38 in the second rotational direction is reduced by plastic deformation or the like, the current with respect to the stroke amount S when the piston 36 moves toward the brake pad 18. The slope of the value I is smaller than that at normal time. Therefore, by comparing the slope of the current value I with respect to the stroke amount S and the slope of the current value I with respect to the stroke amount S in a normal state, it can be determined whether or not the spiral spring 38 is normal.
Second Embodiment

  Hereinafter, a second embodiment of the present invention will be described. The present embodiment is different from the first embodiment in the method of detecting the state of the spiral spring 38. Since the configurations of the electric brake control device 10 and the electric brake device 12 in the present embodiment are the same as those in the first embodiment, description thereof will be omitted.

<Detection of state of spiral spring 38 based on electric energy W>
FIG. 5 is a diagram showing the amount of electric power W supplied to the motor 32 based on the relationship between the stroke amount S of the piston 36 and the current value I supplied to the motor 32. Point O in FIG. 5 indicates the position of the piston 36 in a state where the distance between the piston 36 and the brake pad 18 is maximized. The stroke amount S indicates the distance that the piston 36 has moved from the point O. As shown in FIG. 5, the stroke amount S when the piston 36 moves from the point O toward the brake pad 18 and hits the brake pad 18 is the stroke amount Sa, and the current value I relative to the stroke amount Sa is the current value. Ia.
In FIG. 5, the solid line A indicates the relationship between the stroke amount S and the current value I when the spiral spring 38 is in a normal state, and the alternate long and short dash line B indicates a state where abnormality such as plastic deformation or dropout occurs in the spiral spring 38. The relationship between the stroke amount S and the current value I is shown. The area a of the portion surrounded by the two-dot chain line V passing through the point Sa and parallel to the axis I, the solid line A, and the axis S is necessary to move the piston 36 by the stroke amount Sa when the spiral spring 38 is normal. The amount of electric power W is shown. The area b of the portion surrounded by the two-dot chain line V, the one-dot chain line B, and the axis S represents the amount of electric power W required to move the piston 36 by the stroke amount Sa when an abnormality occurs in the spiral spring 38. Yes.

When an abnormality occurs in the spiral spring 38, the elastic energy accumulated in the spiral spring 38 when the spiral spring 38 is wound in the first rotation direction becomes smaller than normal. That is, since the force for rotating the spring winding shaft 66 in the second rotation direction is smaller than that in the normal state, the current value I with respect to the stroke amount S is small. Therefore, the area b is smaller than the area a.
When the stroke amount S becomes larger than the point Sa, a reaction force is exerted on the piston 36 from the brake pad 18. The magnitude of the elastic energy of the spiral spring 38 is extremely small compared to the magnitude of the reaction force. For this reason, the magnitude of the elastic energy of the spiral spring 38 hardly affects the size of the area.
As described above, the electric brake control device 10 uses the spiral spring 38 based on the electric power W required to move the piston 36 to a position where the piston 36 is pressed against the brake pad 18 and the axial force is exerted on the brake pad 18. Whether or not is normal.

FIG. 6 is a flowchart showing a state detection process of the spiral spring 38 executed in the electric brake control device 10. This process is started, for example, when the occupant is not operating the brake pedal and when a predetermined period has elapsed from the end of the operation of the brake pedal. In S21, the electric brake control device 10 moves the piston 36 to an initial position where the distance between the piston 36 and the brake pad 18 is maximized. Whether the piston 36 has moved to the initial position is determined by, for example, driving the rotor 42 in the second rotational direction for a time sufficient to move the piston 36 from the position where the piston 36 is pressed against the brake pad 18 to the initial position. Thus, it can be determined that the piston 36 has moved to the initial position.
Next, in S23, the electric brake control device 10 resets the electric energy W to zero in the state of S21. In S25, the electric brake control device 10 determines whether the brake pedal is depressed and the signal of the brake switch 7 becomes an ON signal. When the signal of the brake switch 7 is not the ON signal, the process proceeds to S27, and when it is the ON signal, the state detection process based on the flow is terminated.

In S <b> 27, the electric brake control device 10 gradually increases the current of the second current value I <b> ₁ , which is a preset current value I, by a fixed amount every predetermined period, and sequentially supplies the current to the motor 32. Next, the electric brake control device 10 integrates the current value I every predetermined period to calculate the electric energy W. In S29, based on the signal transmitted from the load sensor 86, it is determined whether or not the piston 36 has hit the brake pad 18, that is, whether or not the stroke amount S of the piston 36 has reached the stroke amount Sa.
When the spiral spring 38 is normal, the stroke amount S of the piston 36 reaches the stroke amount Sa at the current value Ia. Therefore, electric energy W is the accumulated value when gradually increasing the current value I from the second current value I ₁ to the current value Ia. On the other hand, when the spiral spring 38 is abnormal, the stroke amount S of the piston 36 reaches the stroke amount Sa when the current of the current value I ₄ is supplied to the motor 32 as shown in FIG. Therefore, the amount of power W at this time is the accumulated value when gradually increasing the current value I from the second current value I ₁ to the current value I _4. When it is determined that the piston 36 has hit the brake pad 18, the process proceeds to S31, and when it is determined that the piston 36 has not hit the brake pad 18, the process returns to S27.

  In S31, the electric brake control device 10 determines the integrated value of the electric energy W required to move the piston 36 calculated in S27 by the stroke amount Sa, and the stroke amount Sa of the piston 36 when the spiral spring 38 is normal. It is determined whether or not the difference between the set values set as the amount of power W required to move only by a larger amount than the threshold value. When the difference between the set value and the integrated value is smaller than the threshold value, it is determined that the spiral spring 38 is normal, and the state detection process based on the flow is ended. If the difference between the set value and the integrated value is larger than the threshold value, it is determined that the spiral spring 38 is abnormal, a warning is issued in S33, and the state detection process based on the flow is terminated.

As described above, in the present embodiment, when the input shaft 54 rotates in the first rotation direction, the spiral spring 38 accumulates elastic energy, and the force to rotate the input shaft 54 in the second rotation direction. It exerts on the input shaft 54. Therefore, when the force to rotate the input shaft 54 of the spiral spring 38 in the second rotational direction becomes small due to plastic deformation or the like, from the point O where the distance between the piston 36 and the brake pad 18 is maximized. The amount of electric power W required to move the piston 36 to the stroke amount Sa that is the position where the piston 36 is pressed against the brake pad 18 is smaller than that in the normal state.
Therefore, by comparing the power amount W required to move the piston 36 from the point O to the stroke amount Sa with the power amount W required to move the piston 36 from the point O to the stroke amount Sa at normal time, It can be determined whether or not the spiral spring 38 is normal. In the second embodiment, the current value I supplied to the motor 32, without reference to the stroke amount S of the piston 36, is intended to be gradually increased by a predetermined amount from the second current value I _1. For this reason, control can be simplified compared with 1st Embodiment which increased the electric current value I with reference to stroke amount S. FIG.

The rotor 42 in the first embodiment and the second embodiment is an example of a motor output shaft, and the current value I and the electric energy W are examples of energization state related quantities. The spiral spring 38 is an example of a piston return spring, and the control unit 13 that executes S7 and S27 is an example of an acquisition unit. The control unit 13 that executes S13 and S31 is an example of an abnormality detection unit, and the point O in the first embodiment is an example of a first position. Position of the piston 36 when moved by a stroke amount S ₃ from the point O in the first embodiment is an example of a second position.

In addition, although the aspect of this invention was demonstrated as mentioned above, the electric brake system 2 containing the electric brake control apparatus 10 of this invention is not restricted to the above-mentioned aspect, In the range which does not deviate from the summary of this invention. Various changes can be made.
In the first embodiment and the second embodiment, the spring used as the piston return spring is the spiral spring 38, but the piston return spring is not limited to this. The piston return spring only needs to exert a force for rotating the rotor 42 in the second rotation direction, and may be, for example, a torsion spring.
In the first embodiment and the second embodiment, the state of the spiral spring 38 is detected using the current value I with respect to the stroke amount S and the amount of power W required to move the piston 36 by the stroke amount Sa. However, the present invention is not limited to this. For example, a voltage value with respect to the stroke amount S may be used.

Moreover, in 1st Embodiment and 2nd Embodiment, the electric brake control apparatus 10 calculates inclination or electric energy from the electric current value I with respect to stroke amount S of piston 36, and the calculated value of the calculated inclination or electric energy is calculated. However, the present invention is not limited to this. The state of the spiral spring may be detected, for example, by directly comparing the current value with respect to the stroke amount and the current value with respect to the same stroke amount when the spiral spring is normal.
In the first and second embodiments, the abnormality is detected when the force to rotate the input shaft 54 of the spiral spring 38 in the second rotational direction is smaller than that in the normal state. Even when the force to rotate the 38 input shafts 54 in the second rotation direction is larger than that in the normal state, the abnormality of the spiral spring 38 can be detected in the same manner.

2: Electric brake system 6: Stroke sensor 7: Brake switch 8: Battery 10: Electric brake control device 12: Electric brake device 13: Control unit 14: Drive circuit 15: Current detection unit 16: Caliper 18: Brake pad 20: Piston Drive device 22: Slider 24: Guide pin 26: Brake rotor 30: Housing 32: Motor 34: Linear motion conversion mechanism 36: Piston 38: Spiral spring 40: Coil 42: Rotor 44: Groove 46: Bearing 48: Magnet 50: Resolver 52: Output cylinder 54: Input shaft 56: Planetary roller 58: Supporting portion 60: Shaft portion 62: Flange portion 64: Projection 66: Spring winding shaft 68: Screw-shaped gear mechanism 70: Helical gear mechanism 72: Output screw part 74: Input screw part 76: Planetary screw part 7 : Output helical gear unit 80: Input helical gear portion 82: planetary helical gear portion 84: hollow portion 86: a load sensor

Claims (3)

An acquisition unit that acquires an energization state related amount indicating an energization state of a motor that moves the piston in a direction in which the piston is pressed against the pad by rotation of the motor output shaft in the first rotation direction;
A spring that accumulates elastic energy by rotating the motor output shaft in the first rotation direction, and releasing the elastic energy causes the motor output shaft to move in a second rotation direction that is opposite to the first rotation direction. An abnormality detector that detects an abnormality of the piston return spring to be rotated, and an electric brake control device comprising:
The abnormality detection unit detects an abnormality of the piston return spring based on the energized state relation amount acquired by the acquisition unit until the piston is pressed against the pad and an axial force is exerted on the pad. An electric brake control device characterized by that. The energization state related amount is an amount related to a current value supplied to the motor,
When the abnormality detection unit has an increase gradient of the current value with respect to the movement amount of the piston when the piston moves from the first position to the second position closer to the pad than the first position is less than a set value The electric brake control device according to claim 1, wherein an abnormality of the piston return spring is detected. The energized state related amount is an amount related to the amount of electric power supplied to the motor,
The abnormality detection unit is necessary for moving the piston from a position where the distance between the piston and the pad is maximized to a position where the piston is pressed against the pad and the axial force is exerted on the pad. The electric brake control device according to claim 1, wherein an abnormality of the piston return spring is detected when the electric energy is equal to or less than a set value.

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