Electrically-driven brake device

Abstract

To enable cancellation of a state where reduction of brake force is restricted even if force is relatively small when the force is input to a disengagement mechanism in order to cancel the state where the reduction of the brake force is restricted by a brake force maintenance mechanism.SOLUTION: A brake force maintenance mechanism 70 permits rotation of a ratchet gear 71 in a reduction direction X2 as engagement of the ratchet gear 71 with a claw member 72 is released when the ratchet gear 71 rotates in an increasing direction X1 in a state where the claw member 72 is engaged with the ratchet gear 71 rotated in association with driving of an electric motor. In a disengagement mechanism 80, a releasing claw 86 comes close to and contacts with the ratchet gear 71 when force is input from the outside to rotate a bolt 81 in a first direction Y1. When the bolt 81 rotates in a first direction Y1 in this state, the ratchet gear 71 is rotated in the increasing direction X1 by the releasing claw 86.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an electric braking device provided in a vehicle. [Background technology]

[0002] Patent Document 1 discloses an electric braking device equipped with a parking brake mechanism. The parking brake mechanism includes a rotating body that rotates in conjunction with an electric motor that is the power source of the electric braking device, and an engaging part that can move forward and backward in a direction toward and away from the rotating body. The rotation direction of the rotating body when the braking force increases is defined as an "increasing direction", and the rotation direction of the rotating body when the braking force decreases is defined as a "decreasing direction". At this time, the parking brake mechanism restricts the rotation of the rotating body in the decreasing direction by engaging the engaging part with the rotating body. This maintains the state in which the braking force is generated. On the other hand, when the rotating body rotates in the increasing direction while the engaging part is engaged with the rotating body, the engagement between the engaging part and the rotating body is released, and the engaging part moves away from the rotating body. This makes it possible to release the state in which the braking force is generated.

[0003] However, when the engaging portion is engaged with the rotating body, an abnormality may occur that makes it impossible to drive the electric motor. In this case, since the rotating body cannot be rotated, the braking force cannot be released.

[0004] The caliper of the electric braking device of Patent Document 1 is provided with an insertion hole for inserting a dedicated tool into the device. When the tool is inserted into the device through the insertion hole, the tip of the tool comes into contact with the rotating body. With the tip of the tool in contact with the rotating body in this manner, the worker can push the tool deep inside the device, thereby rotating the rotating body in the increasing direction. When the rotating body is rotated in the increasing direction by the tool in this manner, the engagement between the engagement portion and the rotating body is released. As a result, the engagement portion moves away from the rotating body. Therefore, it is possible to release the state in which a braking force is being generated even if the electric motor cannot be driven. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-58788 A Summary of the Invention [Problem to be solved by the invention]

[0006] When forcibly rotating a rotating body by pushing a tool in contact with the rotating body deep inside the device as described above, the worker needs to use a very strong force to push the tool deep inside the device. [Means for solving the problem]

[0007] The electric braking device for solving the above problem is a device in which a rotating part of a linear motion conversion mechanism rotates in response to the rotational motion of an electric motor, the rotational motion of the rotating part is converted into linear motion of a linear motion part of the linear motion conversion mechanism, and a braking force is generated at a wheel of a vehicle by adjusting a force pressing a friction material against a first rotating part that rotates integrally with the wheel in response to the linear motion of the linear motion part. The electric braking device has a second rotating part that rotates in conjunction with the drive of the electric motor, and an engaging part that, when engaged with the second rotating part, restricts rotation of the second rotating part in a decreasing direction, which is the rotation direction of the second rotating part when reducing the braking force, while allowing rotation of the second rotating part in an increasing direction, which is the rotation direction of the second rotating part when increasing the braking force, and when the engaging part is engaged with the second rotating part and the second rotating part rotates in the increasing direction, the engaging part is disengaged from the second rotating part to allow rotation of the second rotating part in the decreasing direction. a braking force maintaining mechanism configured as above; a third rotating part that rotates when a force is input from the outside; and an action part that approaches the second rotating part and contacts the second rotating part when the third rotating part rotates in a first direction, and moves in a direction away from the second rotating part when the third rotating part rotates in a second direction that is the opposite direction to the first direction, and an engagement release mechanism configured to increase the force input from the outside and rotate the second rotating part in the increasing direction by the action part when the third rotating part rotates in the first direction with the action part in contact with the second rotating part. Effect of the Invention

[0008] The above-mentioned electric braking device has the advantage that when an external force is input to the disengagement mechanism to release the state in which the reduction in the braking force is restricted by the braking force maintenance mechanism, the state in which the reduction in the braking force is restricted can be released even if the force is relatively small. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an electric braking device according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view that diagrammatically shows a portion of the electric braking device. [Diagram 3] FIG. 3 is a cross-sectional view showing a parking brake device provided in the electric braking device. [Figure 4] FIG. 4 is a cross-sectional view showing the parking brake device. [Diagram 5] FIG. 5 is a cross-sectional view showing the parking brake device. [Figure 6] FIG. 6 is a cross-sectional view that typically shows a portion where a base member and a bolt are screwed together in an engagement release mechanism included in the parking brake device. [Figure 7] FIG. 7 is a cross-sectional view that shows a schematic view of a connecting portion between a bolt and a release pawl in the disengagement mechanism. [Figure 8] FIG. 8 is a cross-sectional view that shows a schematic view of the electric braking device when a tool is inserted into the device from outside. [Figure 9] FIG. 9 is a perspective view showing a bolt in a modified disengagement mechanism. [Figure 10] FIG. 10 is a perspective view showing a state in which the tip of the bolt is engaged with the ratchet gear in the disengaging mechanism of the modified example. [Figure 11] FIG. 11 is a cross-sectional view showing a parking brake device provided with a disengagement mechanism of another modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, one embodiment of an electric braking device will be described with reference to Figs. <Overall configuration of electric braking device> FIG 1 illustrates an electric braking device 20 mounted on a vehicle. The electric braking device 20 is a disc-type electric braking device. The electric braking device 20 includes a brake disc 21 that rotates integrally with the vehicle wheel 11, a caliper 24 supported on the vehicle body, and an MGU 25 connected to the caliper 24. The brake disc 21 corresponds to the "first rotating part." The MGU stands for "motor generator unit."

[0011] The caliper 24 supports a brake pad 22 arranged on one side of the brake disc 21 and a brake pad 23 arranged on the other side of the brake disc 21 in the extension direction of the axle 12 that rotates integrally with the wheel 11. These brake pads 22, 23 correspond to "friction materials." The electric braking device 20 generates a braking force on the wheel 11 by pressing the two brake pads 22, 23 against the brake disc 21.

[0012] The electric braking device 20 includes an electric motor 30 as a power source, a reduction gear mechanism 40, a linear motion conversion mechanism 50, a piston 55, and a parking brake device 60. The linear motion conversion mechanism 50 and the piston 55 are provided in the caliper 24. The electric motor 30, the reduction gear mechanism 40, and the parking brake device 60 are provided in the MGU 25.

[0013] The electric motor 30 has an output shaft 31 that is rotatable in both forward and reverse directions. The reduction mechanism 40 reduces the speed of the rotational motion of the output shaft 31 of the electric motor 30 and outputs the reduced speed to the linear motion conversion mechanism 50. For example, the reduction mechanism 40 has a plurality of gears that mesh with one another. The plurality of gears include an input gear 41 attached to the output shaft 31 and an output gear 42 that outputs the rotational motion to the linear motion conversion mechanism 50. Hereinafter, the rotational motion of the output shaft 31 of the electric motor 30 will be simply referred to as the "rotational motion of the electric motor 30."

[0014] The linear motion conversion mechanism 50 has, for example, a shaft member 51 that rotates integrally with the output gear 42, and a nut 52 that is arranged coaxially with the shaft member 51. The base end of the shaft member 51 is fixed to the output gear 42. The shaft member 51 extends from the base end toward the brake pad 23. The shaft member 51 has a screw portion 511 with a male thread on its circumferential surface. The nut 52 has an inner circumferential surface with a female thread. The nut 52 is arranged coaxially with the shaft member 51 and is screwed into the screw portion 511. Although omitted in FIG. 1, the linear motion conversion mechanism 50 has a rotation restriction portion that restricts the rotation of the nut 52. Therefore, when the shaft member 51 rotates, the nut 52 moves linearly in a direction corresponding to the rotation direction of the shaft member 51. In other words, the shaft member 51 corresponds to the "rotating portion of the linear motion conversion mechanism" that rotates in response to the rotational motion of the electric motor 30. The nut 52 corresponds to the "linear motion portion of the linear motion conversion mechanism." Furthermore, in this embodiment, the linear motion part is disposed coaxially with the rotating part.

[0015] The piston 55 is connected to the nut 52. Therefore, when the nut 52 moves linearly, the piston 55 moves linearly in the same direction as the linear movement of the nut 52. When the piston 55 moves linearly in a direction approaching the brake disc 21, the force pressing the two brake pads 22, 23 against the brake disc 21 increases. On the other hand, when the piston 55 moves linearly in a direction away from the brake disc 21, the force pressing the two brake pads 22, 23 against the brake disc 21 decreases. In other words, the electric braking device 20 can adjust the force pressing the two brake pads 22, 23 against the brake disc 21 by the linear movement of the piston 55.

[0016] <Parking brake system> The configuration of the parking brake device 60 will be described with reference to FIGS. The parking brake device 60 is intended to maintain a braking force even when the power supply to the electric motor 30 is stopped.

[0017] 2 and 3, the parking brake device 60 includes a base member 61, a braking force maintaining mechanism 70, and a disengagement mechanism 80. The base member 61 is fixed to the MGU 25. Both the braking force maintaining mechanism 70 and the disengagement mechanism 80 are attached to the base member 61. Since the MGU 25 is fixed to the caliper 24, it can be said that the base member 61 is fixed to the caliper 24 via the MGU 25.

[0018] <Braking force maintenance mechanism> The braking force maintaining mechanism 70 has a ratchet gear 71, a pawl member 72, a first spring 73, and a solenoid 74. A plurality of teeth 711 are arranged along the circumferential direction on the outer circumferential surface of the ratchet gear 71. The ratchet gear 71 corresponds to a "second rotating part" that rotates in conjunction with the driving of the electric motor 30. In this example, the ratchet gear 71 is fixed to the output shaft 31 of the electric motor 30 in a state in which it can rotate integrally therewith.

[0019] The rotation direction of the output shaft 31 and the ratchet gear 71 when increasing the braking force is defined as the "increasing direction X1." The opposite direction of the increasing direction X1 is defined as the "decreasing direction X2." The decreasing direction X2 is also the rotation direction of the output shaft 31 and the ratchet gear 71 when decreasing the braking force.

[0020] As shown in Fig. 3 and Fig. 4, the pawl member 72 is configured to be movable toward and away from the ratchet gear 71. When the pawl member 72 approaches the ratchet gear 71, the pawl member 72 engages with the teeth 711 of the ratchet gear 71. This restricts the rotation of the output shaft 31 and the ratchet gear 71 in the decrease direction X2 by the pawl member 72, and thus restricts a decrease in the braking force. On the other hand, even if the pawl member 72 engages with the teeth 711, the rotation of the output shaft 31 and the ratchet gear 71 in the increase direction X1 is permitted, and therefore an increase in the braking force is permitted. Therefore, when the pawl member 72 engages with the ratchet gear 71, it corresponds to an "engagement portion" that restricts the rotation of the ratchet gear 71 in the decrease direction X2 while permitting the rotation of the ratchet gear 71 in the increase direction X1.

[0021] The first spring 73 applies a biasing force to the pawl member 72 in a direction away from the ratchet gear 71. As a result, when the pawl member 72 is not engaged with the teeth 711 of the ratchet gear 71, the biasing force of the first spring 73 causes the pawl member 72 to move away from the ratchet gear 71. On the other hand, when the pawl member 72 is engaged with the teeth 711 of the ratchet gear 71, even if a biasing force is applied to the pawl member 72 from the first spring 73, the state in which the pawl member 72 engages with the teeth 711 is maintained.

[0022] The solenoid 74 is a power source for the pawl member 72. That is, when the solenoid 74 is energized, the electromagnetic force generated by the solenoid 74 moves the pawl member 72 in a direction approaching the ratchet gear 71 against the biasing force of the first spring 73. When the pawl member 72 is engaged with the teeth 711 of the ratchet gear 71, the state in which the pawl member 72 is engaged with the teeth 711 is maintained even if the energization of the solenoid 74 is stopped.

[0023] <Disengagement mechanism> As shown in Figs. 4 and 5, the disengagement mechanism 80 includes a bolt 81, a second spring 85, and a release pawl 86. The bolt 81 has a head 82 and a shaft 83. The shaft 83 has a male thread on its circumferential surface. The bolt 81 is rotatably supported by the base member 61. More specifically, the base member 61 is provided with a through hole 61a extending along the axial direction of the bolt 81. The through hole 61a is formed on the circumferential surface of the base member 61 with a female thread. Therefore, the bolt 81 is screwed into the base member 61. The head 82 is located on the opposite side of the base member 61 from the position of the ratchet gear 71.

[0024] The rotation direction of the bolt 81 when the tip of the shaft portion 83 is brought closer to the ratchet gear 71 is defined as the "first direction Y1." The opposite direction of the first direction Y1 is defined as the "second direction Y2." The second direction Y2 is also the rotation direction of the bolt 81 when the tip of the shaft portion 83 is moved away from the ratchet gear 71. Furthermore, of the directions in which the shaft portion 83 moves linearly, the direction in which the tip of the shaft portion 83 is moved away from the base member 61 is defined as the "advance direction Z1." The opposite direction of the advance direction Z1 is defined as the "retraction direction Z2." The retraction direction Z2 is the direction in which the shaft portion 83 moves linearly, the tip of the shaft portion 83 is brought closer to the base member 61.

[0025] Here, as shown in FIG. 2, in the housing constituting the outer shell of the MGU 25, an insertion hole 25a is provided near the position of the disengagement mechanism 80. The insertion hole 25a is usually closed by a cap 26 having a waterproof function. Therefore, from outside the MGU 25, the inside of the MGU 25, i.e., the inside of the housing, cannot be seen through the insertion hole 25a. However, when the cap 26 is removed as shown in FIG. 8, a tool 100 such as a hexagonal wrench can be inserted into the MGU 25 from outside the MGU 25 through the insertion hole 25a. When the tool 100 is inserted into the MGU 25 through the insertion hole 25a, the tip of the tool 100 can be engaged with the head 82 of the bolt 81. When the tool 100 is rotated while engaged with the bolt 81 in this way, the bolt 81 is rotated in a direction corresponding to the rotation direction of the tool 100. In other words, the bolt 81 corresponds to a "third rotating part" that rotates when an external force is input.

[0026] The second spring 85 is disposed between the head 82 of the bolt 81 and the base member 61. The second spring 85 biases the head 82 in a direction to move the head 82 away from the base member 61. As shown in FIG. 6, the threaded portion of the shaft portion 83 is defined as the "thread 831 of the male thread," and the threaded portion of the base member 61 is defined as the "thread 611 of the female thread." At this time, the biasing force of the second spring 85 can press the thread 831 of the male thread against the thread 611 of the female thread. This increases the frictional force generated between the bolt 81 and the base member 61. As a result, the bolt 81 is less likely to rotate in either the first direction Y1 or the second direction Y2. Therefore, when vibrations caused by the running of the vehicle are transmitted to the disengagement mechanism 80, the bolt 81 is restricted from rotating in the first direction Y1. In other words, the second spring 85 corresponds to the "restriction portion." The frictional force restricts the bolt 81 from rotating in the first direction Y1 when vibrations caused by the vehicle traveling are transmitted to the disengagement mechanism 80. Moreover, the frictional force is very small compared to the force required to rotate the bolt 81. Therefore, the effect of the frictional force on the force required to rotate the bolt 81 is very small.

[0027] The release claw 86 is rotatable relative to the shaft portion 83 of the bolt 81, and is connected to the shaft portion 83 so as to move forward and backward in conjunction with the forward and backward movement of the bolt 81. Therefore, when the bolt 81 rotates in the first direction Y1, the release claw 86 moves in the advancing direction Z1 together with the shaft portion 83 without rotating. On the other hand, when the bolt 81 rotates in the second direction Y2, the release claw 86 moves in the retreating direction Z2 together with the shaft portion 83 without rotating. In other words, the release claw 86 corresponds to the "action portion."

[0028] An example of a portion where the release claw 86 is attached to the bolt 81 will be described with reference to FIG. The release claw 86 is provided with a ring-shaped supported portion 861. The shaft portion 83 of the bolt 81 is inserted into the inside of the supported portion 861. A nut 87 is provided at the tip portion of the shaft portion 83 to prevent the supported portion 861 from coming off the bolt 81. In addition, the shaft portion 83 is provided with a ring-shaped restricting member 88 that restricts the supported portion 861 from approaching the head portion 82. The nut 87 and the restricting member 88 restrict the release claw 86 from moving relative to the shaft portion 83 in the axial direction.

[0029] Instead of providing the restricting member 88, the shaft diameter of the shaft portion 83 may be increased to provide a step on the shaft portion 83, thereby preventing the supported portion 861 from coming off the bolt 81. The supported portion 861 is in contact with, for example, the housing of the MGU 25. This restricts the rotation of the supported portion 861 together with the bolt 81 when the bolt 81 rotates in the first direction Y1 or the second direction Y2.

[0030] As shown in FIG. 3 and FIG. 7, the release pawl 86 has a straight portion 862 and a claw portion 863. The straight portion 862 is attached to the supported portion 861. The straight portion 862 extends from the portion attached to the supported portion 861 along the axial direction of the shaft portion 83. The claw portion 863 is connected to the tip of the straight portion 862. The claw portion 863 is configured to approach the rotation center of the ratchet gear 71 as it moves away from the connection portion with the straight portion 862 in the advancement direction Z1. Therefore, as shown in FIG. 5, when the claw portion 863 is engaged with one of the teeth 711 of the ratchet gear 71, contact between the release pawl 86 and the tooth 711 adjacent to the tooth 711 in the decrease direction X2 can be avoided. In other words, the claw portion 863 corresponds to a "claw portion" configured to be able to engage with one of the teeth 711.

[0031] <Actions and Effects of the Present Embodiment> It is assumed that when the braking force maintenance mechanism 70 regulates the reduction in the braking force, an abnormality occurs and the electric motor 30 cannot be driven.

[0032] 8, the worker removes cap 26 from MGU 25. In this state, the worker inserts tool 100, such as a hexagonal wrench, into MGU 25 through insertion hole 25a provided in the housing of MGU 25. Then, the worker engages the tip of tool 100 with head 82 of bolt 81.

[0033] The worker rotates the bolt 81 in the first direction Y1 by rotating the tool 100. Then, the bolt 81 and the release pawl 86 move in the advancing direction Z1. Therefore, the pawl portion 863 of the release pawl 86 approaches the ratchet gear 71. Eventually, as shown in FIG. 5, the pawl portion 863 engages with the teeth 711 of the ratchet gear 71. If the worker continues to rotate the bolt 81 in the first direction Y1 in this state, the bolt 81 and the release pawl 86 move in the advancing direction Z1, so that the release pawl 86 pushes the teeth 711. As a result, the ratchet gear 71 rotates in the increasing direction X1.

[0034] When the ratchet gear 71 rotates in the increasing direction X1, the engagement between the pawl member 72 and the ratchet gear 71 in the braking force maintenance mechanism 70 is released. Then, the biasing force of the first spring 73 causes the pawl member 72 to move in a direction away from the ratchet gear 71. This allows the ratchet gear 71 to rotate in the decreasing direction X2, and releases the state in which the reduction in the braking force is restricted.

[0035] In the electric braking device 20, a force that rotates the ratchet gear 71 in the increasing direction X1 is not directly input to the ratchet gear 71. In other words, the ratchet gear 71 is indirectly rotated in the increasing direction X1 by rotating the bolt 81. Therefore, compared to the conventional technology in which the ratchet gear 71 is directly rotated in the increasing direction X1, even if a small force is externally input to the disengagement mechanism 80, the ratchet gear 71 can be rotated in the increasing direction X1.

[0036] Specifically, the input for rotating the head 82 in the first direction Y1 is defined as "F1", the distance from the rotation center of the bolt 81 to F1 is defined as "r", the pitch of the male thread 611 is defined as "L", and the force for rotating the ratchet gear 71 in the increasing direction X1 is defined as "F2". In this case, according to the work relational expression (Equation 1) when the bolt 81 makes one rotation, generally "2πr >> L" holds, so "F1 << F2" holds.

[0037] 2·π·r×F1 = L×F2 ···(Equation 1) Therefore, when an external force is input to the engagement release mechanism 80 to release the state in which the reduction of the braking force is restricted by the braking force maintaining mechanism 70, the electric braking device 20 can release the state in which the reduction of the braking force is restricted even if the force is relatively small.

[0038] Generally, the electric braking device 20 is provided with a mechanism for rotating the output shaft 31 of the electric motor 30 in the decreasing direction X2 when the driving of the electric motor 30 is stopped. An example of such a mechanism is disclosed in "Japanese Patent Laid-Open No. 2017-7569".

[0039] Therefore, when the operator rotates the bolt 81 in the second direction Y2, the bolt 81 and the release claw 86 move in the withdrawal direction Z2. As a result, the engagement between the release claw 86 and the ratchet gear 71 is released. Then, the ratchet gear 71 and the output shaft 31 of the electric motor 30 rotate in the decreasing direction X2. Thereby, the braking force is reduced.

[0040] In the present embodiment, the following effects can be further obtained. (1) When the claw portion 863 of the release claw 86 is engaged with one tooth 711 among the plurality of teeth 711 of the ratchet gear 71, the release claw 86 is configured to avoid contact with the tooth 711 adjacent to the tooth 711 in the decreasing direction X2. Thereby, when attempting to rotate the bolt 81 in the first direction Y1 to rotate the ratchet gear 71 in the increasing direction X1, the claw member 72 can maintain the state of being engaged with the tooth 711.

[0041] (2) Both the braking force maintaining mechanism 70 and the disengagement mechanism 80 are attached to the base member 61. The braking force maintaining mechanism 70 and the disengagement mechanism 80 can be integrated into a single unit.

[0042] If the braking force maintaining mechanism 70 and the disengagement mechanism 80 are not unitized, then when assembling the electric braking device 20, the braking force maintaining mechanism 70 and the disengagement mechanism 80 need to be attached separately to the MGU 25.

[0043] In contrast to this, in this embodiment, the braking force maintaining mechanism 70 and the disengagement mechanism 80 are formed as a unit, so that the number of work steps required when assembling the electric braking device 20 can be reduced. (3) In the disengagement mechanism 80 of the electric braking device 20, the second spring 85 restricts the bolt 81 from rotating in the first direction Y1. As a result, even if vibrations caused by the vehicle traveling are applied to the disengagement mechanism 80, the bolt 81 is unlikely to rotate in the first direction Y1 due to the vibrations applied to the disengagement mechanism 80. Therefore, the electric braking device 20 can prevent the release pawl 86 from unnecessarily engaging with the teeth 711 of the ratchet gear 71. However, if a force is externally input to the bolt 81 using the tool 100, the bolt 81 can rotate in the first direction Y1 or the second direction Y2.

[0044] (4) In the electric braking device 20, the bolt 81 functions as the third rotating part of the disengagement mechanism 80. By using a ready-made bolt as the bolt 81, a general-purpose tool can be used as the tool 100 for rotating the bolt 81.

[0045] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0046] In the disengagement mechanism 80, the bolt 81 functioning as the third rotation part and the release pawl 86 functioning as the action part are separate, but this is not limited thereto. For example, the member functioning as the third rotation part may also function as the action part. For example, by providing the bolt 81A shown in FIG. 9, the bolt 81A can function as the third rotation part and can also function as the action part.

[0047] 9 and 10, a tip portion 84A of a shaft portion 83A of a bolt 81A has a recess 84Aa that opens to its tip surface. This allows the tip portion 84A of the shaft portion 83A to function as an acting portion. In this case, even if the tip portion 84A, which functions as an acting portion, rotates in the first direction Y1 when the bolt 81 rotates in the first direction Y1, the tip portion 84A can maintain a state in which it is engaged with the teeth 711 of the ratchet gear 71.

[0048] Furthermore, an annular groove 83Aa extending in the circumferential direction is formed on the base end side of the tip portion 84A. This prevents the shaft portion 83A from contacting the tooth 711 adjacent to the tip portion 84A in the decreasing direction X2 when the tip portion 84A is engaged with one of the teeth 711 of the ratchet gear 71.

[0049] The disengagement mechanism 80 may be provided with a spring, instead of the second spring 85, that biases the head 82 of the bolt 81 in a direction that brings the head 82 closer to the base member 61. In this case, the spring functions as a restriction portion of the disengagement mechanism 80.

[0050] The disengagement mechanism does not need to be provided with a spring as long as it can restrict the bolt 81 from rotating in the first direction Y1 when vibrations caused by the vehicle's travel are transmitted to the disengagement mechanism. For example, an adhesive or the like may be used to restrict the bolt 81 from rotating relative to the base member 61. In this case, the adhesive functions as a restricting portion.

[0051] The regulating portion of the disengagement mechanism does not necessarily have to regulate the bolt 81 from rotating in the second direction Y2, so long as it is capable of regulating the bolt 81 from rotating in the first direction Y1 when vibrations caused by the vehicle's travel are transmitted to the disengagement mechanism.

[0052] If the bolt 81 does not rotate in the first direction Y1 even when vibrations caused by the vehicle traveling are transmitted to the disengagement mechanism, the disengagement mechanism does not need to have a restricting portion. The disengagement mechanism and the braking force maintaining mechanism do not need to be integrated into a single unit.

[0053] A disengagement mechanism 80B shown in FIG. 11 may be used as the disengagement mechanism. The disengagement mechanism 80B is disposed on the opposite side of the braking force maintaining mechanism 70 from the disengagement mechanism 80 described in the above embodiment. The disengagement mechanism 80B includes a bolt 81B, which is an example of a third rotating part, and a release claw 86B, which is an example of an action part. The bolt 81B can rotate in both a first direction and a second direction by an external force. In the disengagement mechanism 80B, the first direction is a rotation direction for moving the bolt 81B and the release claw 86B in the retracting direction Z2. The second direction is a rotation direction for moving the bolt 81B and the release claw 86B in the advancing direction Z1.

[0054] In the disengagement mechanism 80B, when the bolt 81B rotates in a first direction, the bolt 81B and the release pawl 86B move in the retracting direction Z2, and the release pawl 86B engages with the teeth 711 of the ratchet gear 71. When the bolt 81B is rotated in the first direction in this state, the release pawl 86B rotates the ratchet gear 71 in the increasing direction X1. This disengages the ratchet gear 71 from the pawl member 72.

[0055] The disengagement mechanism may include a rotating body other than the bolt as a third rotating part. For example, the disengagement mechanism may include a cam that rotates by an external force and a shaft that moves forward and backward in response to the rotation of the cam. With this configuration, when the diameter of the rotation shaft of the cam is larger than the distance between the rotation center and the shaft contact part, the force input to the cam from the outside can be increased. In this case, the shape of the tip of the shaft may be processed so that the tip functions as the acting part. Also, an acting part may be attached to the shaft. In the above disengagement mechanism, the cam functions as the third rotating part.

[0056] The braking force maintaining mechanism may have a configuration different from the braking force maintaining mechanism 70 described in the above embodiment. For example, the braking force maintaining mechanism may be a locking device in JP 2023-28816 A. In this case, the second rotating part of the braking force maintaining mechanism does not have to be a gear.

[0057] The second rotating part of the braking force maintaining mechanism may be attached to a member other than the output shaft 31 of the electric motor 30 in a state in which it can rotate integrally with the member, so long as the second rotating part is a member that rotates in response to the driving of the electric motor 30. For example, the second rotating body may be attached to the shaft member 51 of the linear motion conversion mechanism 50.

[0058] The linear motion conversion mechanism may be a mechanism in which the nut functions as the rotating part and the shaft member functions as the linear motion part. The electric braking device may be a drum-type device, in which case the brake drum functions as the first rotating part and the brake shoes function as the friction material.

[0059] <Other technical ideas> The technical ideas that can be understood from the above-described embodiment and modified examples will be described. (Note 1) The third rotation part of the disengagement mechanism is a bolt that moves forward and backward in association with the rotation in the first direction and the second direction, It is preferable that the action portion is rotatable relative to the bolt and is connected to the bolt so as to move back and forth in conjunction with the forward and backward movement of the bolt.

[0060] (Note 2) It is preferable that the regulating portion of the disengagement mechanism is a spring that applies a biasing force to the bolt in one of the directions of the forward and backward movement of the bolt. [Explanation of symbols]

[0061] 11...Wheel 20…Electric braking device 21...Brake disc (an example of the first rotating part) 22, 23...Brake pads (an example of friction material) 24…Caliper 25…MGU 25a...Through hole 26…Cap 30...Electric motor 50...Linear motion conversion mechanism 51...Shaft member (an example of a rotating part of a linear motion conversion mechanism) 52...Nut (an example of a linear motion part of a linear motion conversion mechanism) 61...Base member 70...Braking force maintenance mechanism 71...Ratchet gear (an example of the second rotating part) 711…tooth 72...claw member (an example of an engagement portion) 80,80B…Disengagement mechanism 81, 81A...Bolt (an example of the third rotating part) 84A…Tip (an example of the action part) 85...Second spring (an example of a restricting part) 86, 86B... Release claw (an example of an action part) 863...Claw part (example of claw part)

Claims

1. An electric braking device in which a rotating part of a linear motion conversion mechanism rotates in response to rotational motion of an electric motor, the rotational motion of the rotating part is converted into linear motion of a linear motion part of the linear motion conversion mechanism, and a braking force is generated at a wheel of a vehicle by adjusting a force pressing a friction material against a first rotating part which rotates integrally with the wheel, in response to the linear motion of the linear motion part, a braking force maintenance mechanism having a second rotating part that rotates in conjunction with the drive of the electric motor, and an engaging part that, when engaged with the second rotating part, restricts rotation of the second rotating part in a decreasing direction, which is the rotation direction of the second rotating part when reducing the braking force, while allowing rotation of the second rotating part in an increasing direction, which is the rotation direction of the second rotating part when increasing the braking force, and is configured to allow rotation of the second rotating part in the decreasing direction by releasing the engagement between the engaging part and the second rotating part when the second rotating part rotates in the increasing direction with the engaging part engaged with the second rotating part; a third rotating part that rotates when a force is input from the outside; and an action part that approaches the second rotating part and contacts the second rotating part when the third rotating part rotates in a first direction, and moves in a direction away from the second rotating part when the third rotating part rotates in a second direction that is the opposite direction to the first direction, and an engagement release mechanism configured to increase the force input from the outside and rotate the second rotating part in the increasing direction by the action part when the third rotating part rotates in the first direction with the action part in contact with the second rotating part. An electric braking device comprising:

2. the second rotating portion is a gear having a plurality of teeth arranged along a circumferential direction, The action portion is provided with a claw portion configured to be able to engage with one of the plurality of teeth of the gear, The action portion is configured to avoid contact with one tooth of the plurality of teeth in the decreasing direction when the claw portion is engaged with the one tooth.

2. The electric braking device according to claim 1.

3. a base member to which the braking force maintaining mechanism is attached, The disengagement mechanism is attached to the base member.

2. The electric braking device according to claim 1.

4. The disengagement mechanism is provided with a restricting portion that restricts the third rotation portion from rotating in the first direction due to vibration applied to the disengagement mechanism. The electric braking device according to any one of claims 1 to 3.

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