Electrically-driven cylinder device and brake fluid pressure control device

Abstract

To obtain an electrically-driven cylinder device which can inhibit a rotary member from being removed from a rotation transmission member as one example.SOLUTION: As one example, an electrically-driven cylinder device according to an embodiment has: a rotation transmission member which is configured to rotate around a rotation axis and is provided with a through hole extending in an axial direction; a rotary member which has a screw part provided with a first thread, and a protruding part protruding from the screw part in a first axial direction and fitted in the through hole, the rotary member provided with a hole located at an end of the protruding part in the first axial direction; a linear motion member which has a second thread to be attached to the first thread through balls, moves in the first axial direction or a second axial direction in response to rotation of the rotary member, and moves in the second axial direction to push a piston; a motor which rotationally drives the rotary member; and an extension member which is fitted in the hole and expands the protruding part so as to inhibit the protruding part from being removed from the through hole.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to an electric cylinder device and a brake fluid pressure control device. [Background technology]

[0002] A conventional electric cylinder device includes a rotary-to-linear motion conversion mechanism that converts rotary motion into linear motion, and a piston that is advanced by the rotary-to-linear motion conversion mechanism. The piston that is advanced by the rotary-to-linear motion conversion mechanism reduces the volume of a liquid chamber and increases the pressure in the liquid chamber.

[0003] The rotary-linear conversion mechanism has a rotating member that rotates and a linear member that moves linearly. The electric cylinder device further has a rotation transmission member that transmits rotation between the rotating member and the motor. The rotating member is attached to the rotation transmission member (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-048122 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional configuration, although the motor output and the pressure in the liquid chamber are balanced during normal use, if the motor loses power, for example, the pressure in the liquid chamber will push the piston and the linear motion member, which may cause the linear motion member to collide with other members. In this case, the rotating member will receive a force in a direction to come off the rotation transmission member due to the reaction force applied by the linear motion member, which may affect the durability of the connection between the rotating member and the rotation transmission member.

[0006] Therefore, the present invention has been made in consideration of the above, and provides an electric cylinder device and a brake fluid pressure control device that are capable of preventing a rotating member from coming off a rotation transmission member. [Means for solving the problem]

[0007] As an example, an electric cylinder device according to an embodiment of the present invention includes: a rotation transmission member configured to rotate around a rotation axis and provided with a through hole extending in an axial direction along the rotation axis; a screw portion provided with a first screw thread; and a protrusion protruding from the screw portion in a first axial direction along the rotation axis and fitted into the through hole, with a hole provided at an end of the protrusion in the first axial direction; a housing provided with a cylinder; a piston arranged in the cylinder; a ball; and a linear motion member having a second screw thread attached to the first screw thread via the ball, which moves in the first axial direction or a second axial direction opposite to the first axial direction in response to rotation of the rotating member and pushes the piston by moving in the second axial direction; a motor that drives the rotating member to rotate around the rotation axis via the rotation transmission member; and an expansion member that is fitted into the hole and expands the protrusion to restrict the protrusion from coming out of the through hole. Therefore, as an example, in the electric cylinder, the protrusion can be more reliably fixed in the through hole by the expansion member remaining in the hole even after manufacturing, compared to when the protrusion is fixed in the through hole by crimping or pressing. Therefore, the electric cylinder device can prevent the rotating member from coming off the rotation transmission member. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view that illustrates a brake system according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view partially showing a rotating member and a gear of the first embodiment. [Diagram 3] FIG. 3 is a rear view showing the rotating member of the first embodiment. [Figure 4]FIG. 4 is a cross-sectional view partially showing a rotating member and gears according to a modified example of the first embodiment. [Diagram 5] FIG. 5 is a cross-sectional view partially showing a rotating member and a gear according to the second embodiment. [Figure 6] FIG. 6 is a cross-sectional view partially showing a rotating member and a gear according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) The first embodiment will be described below with reference to FIGS. 1 to 3. In this specification, components according to the embodiment and their descriptions may be described in a number of ways. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may be identified by names different from those in this specification. The components may also be described by expressions different from those in this specification.

[0010] In the following description, "suppress" is defined as, for example, preventing the occurrence of an event, action, or influence, or reducing the severity of an event, action, or influence. Also, in the following description, "restrict" is defined as, for example, preventing movement or rotation, or allowing movement or rotation within a predetermined range and preventing movement or rotation beyond the predetermined range.

[0011] 1 is a cross-sectional view that shows a schematic diagram of a brake system 10 according to a first embodiment. The brake system 10 is mounted on a vehicle 1 such as a four-wheeled automobile. However, the brake system 10 is not limited to this example.

[0012] The brake system 10 includes a brake fluid pressure control device 11 and a plurality of wheel cylinders 12. The brake system 10 may further include various other components, such as a master cylinder, a pump, and a solenoid valve.

[0013] The brake fluid pressure control device 11 controls, for example, the fluid pressure of at least one of the plurality of wheel cylinders 12. The brake fluid pressure control device 11 has an electric cylinder device 21, an electronic control unit (ECU) 22, and a plurality of fluid paths 23.

[0014] The electric cylinder device 21 is connected to at least one of the multiple wheel cylinders 12 via a fluid path 23. The electric cylinder device 21 can increase the pressure of the brake fluid in the wheel cylinder 12 to generate a braking force for the vehicle 1. The electric cylinder device 21 has a housing 31, a piston 32, two seals 33, 34, a reservoir 35, a rotary-linear motion conversion mechanism 36, a motor 37, a reduction mechanism 38, and an expansion member 39.

[0015] The housing 31 is formed in a substantially cylindrical shape. A cylinder 41 is provided inside the housing 31. The cylinder 41 is a substantially cylindrical space extending along a central axis Ax. The central axis Ax is an example of a rotation axis. The central axis Ax is, for example, a virtual central axis of the cylinder 41. Note that the central axis of the cylinder 41 may be different from the central axis Ax.

[0016] In this specification, for convenience, the axial direction, radial direction, and circumferential direction are defined. The axial direction is a direction along the central axis Ax. The axial direction includes the rearward direction Db and the forward direction Df. The rearward direction Db is a direction along the central axis Ax and is an example of a first axial direction. The forward direction Df is the opposite direction to the rearward direction Db and is an example of a second axial direction. Note that the rearward direction Db and the forward direction Df may be different from the fore-and-aft direction of the vehicle 1. The radial direction is a direction perpendicular to the central axis Ax. The circumferential direction is a direction around the central axis Ax.

[0017] An output port 42 and an input port 43 are further provided in the housing 31. The output port 42 and the input port 43 each communicate with the cylinder 41. In the axial direction, the output port 42 is spaced from the input port 43 in the forward direction Df.

[0018] The piston 32 is disposed in the cylinder 41. The piston 32 is capable of moving in the axial direction inside the cylinder 41. The piston 32 defines a part of the cylinder 41 as a liquid chamber 45. The liquid chamber 45 is provided in the axial direction between the piston 32 and an end 41a of the cylinder 41 in the forward direction Df.

[0019] The output port 42 communicates with a fluid chamber 45. The fluid chamber 45 is connected to the wheel cylinder 12 through the output port 42 and the fluid passage 23. The piston 32 reduces the volume of the fluid chamber 45 by moving in the forward direction Df. This allows the electric cylinder device 21 to increase the pressure of the brake fluid in the fluid chamber 45 and the wheel cylinder 12.

[0020] On the other hand, the piston 32 moves in the rear direction Db to increase the volume of the fluid chamber 45. This allows the electric cylinder device 21 to reduce the pressure of the brake fluid in the fluid chamber 45 and the wheel cylinder 12.

[0021] In the radial direction, a gap is provided between the housing 31 and the piston 32. The gap allows the piston 32 to move axially relative to the housing 31. Two seals 33, 34 seal the gap.

[0022] The seal 33 is spaced from the seal 34 in the forward direction Df. In the axial direction, the output port 42 communicates with the liquid chamber 45 at a position spaced from the seal 33 in the forward direction Df. In the axial direction, the input port 43 communicates with the cylinder 41 between the two seals 33, 34. The seal 33 seals between the liquid chamber 45 and the input port 43.

[0023] The reservoir 35 is connected to the input port 43 through the fluid path 23. The reservoir 35 stores brake fluid. For example, the reservoir 35 is open to the atmosphere, so that the pressure of the reservoir 35 is maintained at atmospheric pressure.

[0024] When the piston 32 moves in the rear direction Db beyond a predetermined position, the input port 43 and the fluid chamber 45 communicate with each other. This allows the brake fluid to flow freely between the fluid chamber 45 and the reservoir 35, and the pressure in the fluid chamber 45 drops to atmospheric pressure.

[0025] The rotary-linear motion conversion mechanism 36 is disposed inside the cylinder 41. In this embodiment, the rotary-linear motion conversion mechanism 36 is, for example, a ball screw. The rotary-linear motion conversion mechanism 36 has a rotating member 51, a linear motion member 52, and a plurality of balls 53.

[0026] In this embodiment, the rotating member 51 may also be referred to as a screw shaft. The linear motion member 52 may also be referred to as a nut. The rotary-linear motion conversion mechanism 36 is not limited to this example. For example, the rotating member may have a nut, and the linear motion member may have a screw shaft.

[0027] The rotating member 51 has a threaded portion 61 and a protruding portion 62. The threaded portion 61 and the protruding portion 62 are each formed in a substantially cylindrical shape extending along the central axis Ax. Note that the protruding portion 62 is not limited to this example, and may be formed in, for example, a quadrangular prism shape.

[0028] The threaded portion 61 has an outer peripheral surface 61a. The outer peripheral surface 61a is a substantially cylindrical curved surface extending along the central axis Ax and faces radially outward. A male thread 61b is provided on the outer peripheral surface 61a. The male thread 61b is an example of a first thread. When the rotating member has a nut, the rotating member is provided with a female thread.

[0029] A center hole 65 is provided at an end of the threaded portion 61 in the forward direction Df. The center hole 65 extends from the end of the threaded portion 61 in the forward direction Df in the rear direction Db along the central axis Ax. For example, when the rotating member 51 is machined by a lathe, a center is fitted into the center hole 65.

[0030] The protruding portion 62 protrudes in the rear direction Db from an end of the threaded portion 61 in the rear direction Db. The protruding portion 62 has an outer circumferential surface 62a and an end face 62b. The outer circumferential surface 62a is an example of an outer surface.

[0031] The outer peripheral surface 62a extends along the central axis Ax and faces radially outward as a whole. The outer peripheral surface 62a may have a portion facing in a direction different from the radial direction. The maximum diameter of the outer peripheral surface 62a of the protruding portion 62 is smaller than the maximum diameter of the outer peripheral surface 61a of the threaded portion 61.

[0032] The end surface 62b is an end of the protruding portion 62 in the rear direction Db and faces the rear direction Db. A hole 67 is provided in the end surface 62b. The hole 67 may also be referred to as a recess, for example. The hole 67 is recessed from the end surface 62b in the forward direction Df along the central axis Ax. The hole 67 may penetrate the rotating member 51.

[0033] The linear motion member 52 is formed in a substantially cylindrical shape extending along the central axis Ax. The linear motion member 52 is attached to the piston 32 or supports the piston 32. The piston 32 is located between the end 41a of the cylinder 41 and the linear motion member 52.

[0034] The linear motion member 52 has an inner peripheral surface 52a. The inner peripheral surface 52a is a substantially cylindrical curve extending along the central axis Ax and faces inward in the radial direction. The inner peripheral surface 52a faces an outer peripheral surface 61a of the threaded portion 61.

[0035] A female screw 52b is provided on the inner circumferential surface 52a. The female screw 52b is an example of a second screw thread. The linear motion member 52 may further be provided with a circulation path connecting both ends of the female screw 52b. When the linear motion member has a screw shaft, the linear motion member is provided with a male screw.

[0036] The balls 53 are, for example, held by the female screw 52b so as to be rotatable and circulatable, and fitted into the male screw 61b.

[0037] The motor 37 is disposed outside the housing 31. The motor 37 is, for example, a brushless motor. However, the motor 37 may be another type of motor. The motor 37 has an output shaft 37a, and is controlled by, for example, the ECU 22 to rotate the output shaft 37a.

[0038] The speed reduction mechanism 38 has three gears 71, 72, and 73 and a bearing 74. Note that the speed reduction mechanism 38 is not limited to this example and may be, for example, a planetary gear mechanism. The gear 71 is an example of a rotation transmission member.

[0039] The reduction mechanism is not essential, and for example, a structure may be adopted in which the rotation of the output shaft of the motor is transmitted to the rotation transmission member without being reduced in speed. In this case, as one example, the motor is disposed on the extension of the axis of the rotation transmission member and the rear side of the rotating member, and the output shaft of the motor is directly connected to the rotation transmission member.

[0040] The gear 71 is accommodated in the housing 31 so as to be rotatable about a central axis Ax at a position spaced in the rear direction Db from the seal and the linear motion member 52. The gear 71 has a journal portion 75 and a plurality of teeth .

[0041] The shaft support portion 75 is formed in a substantially disk shape that is substantially perpendicular to the central axis Ax. The housing 31 supports the shaft support portion 75 rotatably around the central axis Ax via a bearing 74. The shaft support portion 75 may be integral with an inner ring of the bearing 74.

[0042] The pivot support portion 75 has a front surface 75a and a rear surface 75b. The front surface 75a is formed substantially flat and faces the forward direction Df. The rear surface 75b is located on the opposite side to the front surface 75a. The rear surface 75b is formed substantially flat and faces the rear direction Db.

[0043] A through hole 78 is provided in the shaft support portion 75. The through hole 78 penetrates the gear 71 along the central axis Ax. That is, the through hole 78 extends in the axial direction and opens to the front surface 75a and the rear surface 75b.

[0044] The protrusion 62 of the rotating member 51 is fitted into the through hole 78 and attached to the gear 71. The rotating member 51 and the gear 71 are capable of rotating integrally around the central axis Ax. A front surface 75a of the bearing portion 75 contacts the threaded portion 61, restricting the rotating member 51 from moving in the rear direction Db relative to the gear 71.

[0045] The through hole 78 may be spaced apart from the central axis Ax in the radial direction. For example, the journal portion 75 may be provided with a plurality of through holes 78 arranged in the circumferential direction. In this case, the rotating member 51 has a plurality of protruding portions 62 arranged in the circumferential direction. The plurality of protruding portions 62 are fitted into the plurality of through holes 78.

[0046] The support portion 75 further has an inner peripheral surface 75c that forms the through hole 78. The inner peripheral surface 75c is an example of an inner surface. The inner peripheral surface 75c extends along the central axis Ax and faces radially inward as a whole. The inner peripheral surface 75c may have a portion that faces in a direction different from the radial direction. The inner peripheral surface 75c of the support portion 75 and the outer peripheral surface 62a of the protruding portion 62 face each other. The inner peripheral surface 75c is in at least partial contact with the outer peripheral surface 62a of the protruding portion 62.

[0047] A plurality of teeth 76 are provided on the radially outer end of the journal portion 75. The teeth 76 mesh with the teeth of the gear 72. Furthermore, the teeth of the gear 72 mesh with the teeth of the gear 73. The gear 73 is attached to the output shaft 37a so as to be rotatable integrally with the output shaft 37a.

[0048] The reduction gear mechanism 38 transmits the rotation of the output shaft 37a of the motor 37 to the rotating member 51. The motor 37 rotates the rotating member 51 in one direction about the central axis Ax (hereinafter referred to as the forward direction) or in the other direction about the central axis Ax (hereinafter referred to as the reverse direction) via gears 71, 72, and 73 of the reduction gear mechanism 38.

[0049] When the rotating member 51 rotates in the forward direction, the male screw 61b of the rotating member 51 pushes the female screw 52b of the linear moving member 52 in the forward direction Df via the ball 53. Furthermore, the linear moving member 52 pushes the piston 32 in the forward direction Df. As a result, the linear moving member 52 and the piston 32 move (advance) in the forward direction Df. That is, by moving in the forward direction Df, the linear moving member 52 pushes the piston 32 so as to reduce the volume of the liquid chamber 45.

[0050] On the other hand, when the rotating member 51 rotates in the reverse direction, the male screw 61b of the rotating member 51 pushes the female screw 52b of the linear moving member 52 in the rear direction Db via the ball 53. If the piston 32 is attached to the linear moving member 52, the piston 32 moves (retracts) in the rear direction Db together with the linear moving member 52. If the piston 32 is not attached to the linear moving member 52, the linear moving member 52 moves in the rear direction Db. On the other hand, the pressure of the brake fluid in the fluid chamber 45 (wheel cylinder 12) moves (retracts) the piston 32 in the rear direction Db. That is, the linear moving member 52 moves in the forward direction Df or the rearward direction Db in response to the rotation of the rotating member 51.

[0051] Fig. 2 is a cross-sectional view partially showing the rotating member 51 and the gear 71 of the first embodiment. Fig. 3 is a rear view showing the rotating member 51 of the first embodiment. As shown in Fig. 2, the length of the protruding portion 62 of the first embodiment is approximately equal to the length of the through hole 78 in the axial direction.

[0052] Substantially the entire protrusion 62 is housed in the through hole 78. In the axial direction, an end of the protrusion 62 in the rear direction Db is at substantially the same position as an end of the through hole 78 in the rear direction Db. Note that, in the axial direction, the end of the protrusion 62 in the rear direction Db may be located between both ends of the through hole 78 in the axial direction.

[0053] The outer circumferential surface 62a of the protrusion 62 has a cylindrical region 81 and a rotation limiting region 82. Each of the cylindrical region 81 and the rotation limiting region 82 is a part of the outer circumferential surface 62a and is at least partially located inside the through hole 78.

[0054] The cylindrical region 81 is a substantially cylindrical curved surface extending along the central axis Ax. The cylindrical region 81 is located between the rotation limiting region 82 and the threaded portion 61. The cylindrical region 81 is provided with, for example, a recess 84.

[0055] The recesses 84 are, for example, a plurality of recesses formed by rough machining, a spiral groove formed by thread machining, a plurality of grooves formed by knurling and intersecting each other, or a plurality of recesses formed by sandblasting. Note that the recesses 84 are not limited to these examples. The recesses 84 increase the friction coefficient (sliding resistance) of the cylindrical region 81 at least in the axial direction.

[0056] The rotation limiting region 82 is located between the end face 62b and the cylindrical region 81. A plurality of grooves 86 are provided in the rotation limiting region 82. On the other hand, no grooves 86 are provided in the cylindrical region 81. That is, the plurality of grooves 86 are not provided throughout the entire interior of the through hole 78 in the axial direction, but are located in a portion of the interior of the through hole 78 in the axial direction. Note that the grooves 86 are not limited to this example.

[0057] Each of the multiple grooves 86 opens to the end face 62b of the protruding portion 62 and the rotation limiting region 82, and extends in the axial direction. As shown in Fig. 3, the multiple grooves 86 are aligned around the central axis Ax. As a result, the protruding portion 62 is provided with multiple teeth 87. The multiple teeth 87 are aligned around the central axis Ax via the grooves 86.

[0058] The maximum diameter of the rotation-limiting region 82 is smaller than the maximum diameter of the cylindrical region 81. The maximum diameter of the rotation-limiting region 82 is the outer diameter of the rotation-limiting region 82, i.e., the distance between the central axis Ax and the tip of the tooth 87.

[0059] 2, the grooves 86 extend in the forward direction Df from an end of the outer circumferential surface 62a in the rear direction Db. Meanwhile, the grooves 86 are spaced in the rear direction Db from an end of the through hole 78 in the front direction Df.

[0060] The inner circumferential surface 75c of the journal portion 75 has a cylindrical region 91 and a rotation limiting region 92. The cylindrical region 91 and the rotation limiting region 92 are each a part of the inner circumferential surface 75c. The cylindrical region 91 is a substantially cylindrical curved surface extending along the central axis Ax. The cylindrical region 91 is located between the rotation limiting region 92 and the front surface 75a of the journal portion 75.

[0061] The cylindrical region 91 of the inner circumferential surface 75c is longer in the axial direction than the cylindrical region 81 of the outer circumferential surface 62a. The cylindrical region 91 is in contact with the cylindrical region 81 of the outer circumferential surface 62a. The cylindrical region 91 is provided with, for example, a recess 94.

[0062] The recesses 94 are, for example, a plurality of recesses formed by rough machining, a spiral groove formed by thread machining, a plurality of grooves formed by knurling and intersecting each other, or a plurality of recesses formed by sandblasting. Note that the recesses 94 are not limited to these examples. The recesses 94 increase the friction coefficient (sliding resistance) of the cylindrical region 91 at least in the axial direction.

[0063] The rotation limiting region 92 is located between the rear surface 75b of the journal portion 75 and the cylindrical region 91. A plurality of grooves 96 are provided in the rotation limiting region 92. On the other hand, no grooves 96 are provided in the cylindrical region 91. That is, the plurality of grooves 96 are not provided throughout the entire interior of the through hole 78 in the axial direction, but are located in a portion of the interior of the through hole 78 in the axial direction. Note that the grooves 96 are not limited to this example.

[0064] Each of the multiple grooves 96 opens to the rear surface 75b and the rotation limiting region 92, and extends in the axial direction. The multiple grooves 96 are aligned around the central axis Ax. As a result, a multiple number of teeth 97 are provided on the journal portion 75. The multiple teeth 97 are aligned around the central axis Ax via the grooves 96.

[0065] The minimum diameter of the rotation-limiting region 92 is smaller than the minimum diameter of the cylindrical region 91. The minimum diameter of the rotation-limiting region 92 is the inner diameter of the rotation-limiting region 92, i.e., the distance between the central axis Ax and the tip of the tooth 97.

[0066] The grooves 96 extend in the forward direction Df from an end of the inner circumferential surface 75c in the rear direction Db. Meanwhile, the grooves 96 are spaced in the rear direction Db from an end of the through hole 78 in the front direction Df. The grooves 96 in the rotation limiting region 92 are shorter in the axial direction than the grooves 86 in the rotation limiting region 82.

[0067] The plurality of teeth 87 of the rotation limiting region 82 and the plurality of teeth 97 of the rotation limiting region 92 mesh with each other. That is, the teeth 87 fit into the groove 96. On the other hand, the teeth 97 fit into the groove 86. As a result, the plurality of teeth 87 of the rotation limiting region 82 and the plurality of teeth 97 of the rotation limiting region 92 limit the relative rotation of the rotating member 51 and the gear 71 around the central axis Ax.

[0068] As described above, the rotation limiting regions 82, 92 are connected to each other as a spline having a plurality of grooves 86, 96 and a plurality of teeth 87, 97. However, the rotation limiting regions 82, 92 are not limited to this example. For example, the rotation limiting regions 82, 92 may be connected to each other as serrations or may be connected to each other by a key.

[0069] The protrusion 62 has a first inner circumferential surface 62c and a second inner circumferential surface 62d that form a hole 67. The first inner circumferential surface 62c and the second inner circumferential surface 62d are substantially cylindrical curved surfaces extending along the central axis Ax and are aligned in the axial direction.

[0070] The first inner circumferential surface 62c is located between the end surface 62b and the second inner circumferential surface 62d. The first inner circumferential surface 62c is located on the opposite side of the rotation limiting region 82. Note that a part of the first inner circumferential surface 62c may be located on the opposite side of the cylindrical region 81.

[0071] The second inner circumferential surface 62d is located on the opposite side to the cylindrical region 81. Note that a part of the second inner circumferential surface 62d may be located on the opposite side to the rotation limiting region 82. The diameter of the second inner circumferential surface 62d is smaller than the diameter of the first inner circumferential surface 62c. Note that the diameter of the second inner circumferential surface 62d may be the same as the diameter of the first inner circumferential surface 62c.

[0072] The extension member 39 is, for example, a ball. In this embodiment, the extension member 39, the rotating member 51, and the gear 71 are made of metal. The rigidity of the extension member 39 is higher than the rigidity of the rotating member 51. Note that the extension member 39, the rotating member 51, and the gear 71 are not limited to this example.

[0073] The expansion member 39 is fitted into the hole 67. The diameter of the expansion member 39 is smaller than the diameter of the first inner circumferential surface 62c. Furthermore, the diameter of the expansion member 39 is equal to or larger than the diameter of the second inner circumferential surface 62d. The expansion member 39 comes into contact with the second inner circumferential surface 62d, and expands the portion of the protrusion 62 located inside the through hole 78 radially outward.

[0074] The expansion member 39 contacts the second inner circumferential surface 62d, and thus expands the protrusion 62 so that the diameter of the cylindrical region 81 increases. As a result, the cylindrical region 81 of the protrusion 62 is pressed against the cylindrical region 91 of the gear 71. Therefore, the normal force increases between the two cylindrical regions 81, 91, and thus the frictional force increases.

[0075] The frictional force between the cylindrical region 81 of the protrusion 62 and the cylindrical region 91 of the gear 71 restricts the protrusion 62 from slipping out of the through hole 78 in the forward direction Df. That is, the expansion member 39 expands the protrusion 62, thereby increasing the force (frictional force) fixing the protrusion 62 and the gear 71 in the axial direction, and restricts the protrusion 62 from slipping out of the through hole 78.

[0076] Furthermore, the frictional force between the cylindrical region 81 of the protrusion 62 and the cylindrical region 91 of the gear 71 restricts the relative rotation of the rotating member 51 and the gear 71 around the central axis Ax. That is, the expansion member 39 expands the protrusion 62, thereby increasing the force (frictional force) fixing the protrusion 62 and the gear 71 in the circumferential direction, and restricts the relative rotation of the rotating member 51 and the gear 71 around the central axis Ax.

[0077] The expansion member 39 is not limited to a ball. For example, the expansion member 39 may be a substantially conical plug. The expansion member 39 may also be a tapered screw. In this case, for example, a female screw corresponding to the tapered screw is provided on the second inner circumferential surface 62d.

[0078] 3, the protruding portion 62 is further provided with a plurality of slits 101. Each of the plurality of slits 101 extends from the end surface 62b of the protruding portion 62 in the forward direction Df, and connects the hole 67 with the outside of the protruding portion 62.

[0079] 2, the slit 101 extends, for example, from the end face 62b in the forward direction Df to the vicinity of the screw portion 61. Note that the slit 101 may extend in another direction, may be spaced apart from the screw portion 61, or may be provided in the protruding portion 62 and a part of the screw portion 61.

[0080] The slits 101 open to, for example, the first inner circumferential surface 62c and the second inner circumferential surface 62d. Furthermore, as shown in Fig. 3, the slits 101 open to the tooth bottom (the bottom of the groove 86) in the rotation limiting region 82. In other words, the slits 101 communicate with one of the multiple grooves 86. This makes it possible for the slits 101 to suppress a reduction in the number of teeth 87.

[0081] The provision of the slits 101 reduces the rigidity of the protruding portion 62 in the radial direction. Therefore, the expansion member 39 can easily expand the protruding portion 62. The slits 101 may be omitted.

[0082] The pressure of the brake fluid in the fluid chamber 45 (wheel cylinder 12) of the cylinder 41 pushes the piston 32 in the rear direction Db. The motor 37 drives the rotary-linear motion conversion mechanism 36, so that the piston 32 and the linear motion member 52 are maintained at desired positions.

[0083] On the other hand, for example, when the supply of power to the motor 37 is lost, the piston 32 and the linear moving member 52 move in the rear direction Db due to the pressure of the brake fluid. When the linear moving member 52 moves in the rear direction Db, it may collide with, for example, the front surface 75a of the journal portion 75 of the gear 71 or a disc spring. The linear moving member 52 pulls the rotating member 51 in the forward direction Df via the ball 53 due to the reaction force of the collision.

[0084] The expansion member 39 expands the protrusion 62 and presses the outer circumferential surface 61a of the protrusion 62 against the inner circumferential surface 75c of the gear 71. Therefore, the expansion member 39 resists the reaction force applied from the linear motion member 52 and suppresses the protrusion 62 from slipping out of the through hole 78 in the forward direction Df.

[0085] The following describes an example of a method for connecting the rotating member 51 and the gear 71, which is part of a manufacturing method for the electric cylinder device 21. Note that the manufacturing method for the electric cylinder device 21 is not limited to the following method, and other methods may be used.

[0086] The above-mentioned center hole 65 and another center hole 111 shown in Fig. 2 are provided in a rod-shaped metal member that is the material of the rotating member 51. A center is fitted into the center holes 65, 111, and the rotating member 51 is manufactured from the metal member by a lathe. For example, a male thread 61b is formed in the threaded portion 61, and a cylindrical region 81 is formed in the protruding portion 62. Separately, a recess 84 is formed in the cylindrical region 81, and a groove 86 of a rotation limiting region 82 is also formed in the protruding portion 62.

[0087] Next, hole 67 is formed at approximately the same position as center hole 111. Hole 67 is larger than center hole 111. Therefore, by forming hole 67, protrusion 62 loses center hole 111. Note that hole 67 may include a part of the remaining center hole 111. Furthermore, slit 101 is formed by slotting. Note that slit 101 may be omitted.

[0088] Next, the protrusion 62 is inserted in the rear direction Db into the through hole 78. The screw portion 61 abuts against the front surface 75a of the journal portion 75, thereby positioning the rotation member 51 in the axial direction relative to the gear 71. Note that the screw portion 61 may be spaced apart from the front surface 75a.

[0089] The protruding portion 62 is, for example, press-fitted into the through hole 78. Specifically, before the protruding portion 62 is inserted into the through hole 78, the diameter of the cylindrical region 81 is larger than the diameter of the cylindrical region 91. Therefore, the cylindrical region 81 of the protruding portion 62 is press-fitted into the inside of the cylindrical region 91 of the gear 71.

[0090] The rotation limiting region 82 of the protruding portion 62 does not have to be press-fitted into the inside of the rotation limiting region 92 of the gear 71. For example, the tip circle diameter of the tooth 87 is smaller than the root circle diameter of the tooth 97, and the root circle diameter of the tooth 87 is smaller than the tip circle diameter of the tooth 97. Also, a small gap is provided between the teeth 87 and 97 in the circumferential direction. This allows the rotation limiting region 82 of the protruding portion 62 to be smoothly inserted into the through hole 78. Note that the rotation limiting region 82 of the protruding portion 62 may be coupled to the rotation limiting region 92 of the gear 71 by a tight fit.

[0091] The outer peripheral surface 62a of the protruding portion 62 may not have the rotation limiting region 82. In this case, the protruding portion 62 is press-fitted into the inside of the rotation limiting region 92 of the journal portion 75. As a result, the multiple teeth 97 of the rotation limiting region 92 bite into the outer peripheral surface 62a of the protruding portion 62, limiting the relative rotation of the rotating member 51 and the gear 71 around the central axis Ax.

[0092] Conversely, the inner circumferential surface 75c of the journal portion 75 may not have the rotation limiting region 92. In this case, the rotation limiting region 82 of the protrusion 62 is press-fitted into the through-hole 78. As a result, the multiple teeth 87 of the rotation limiting region 82 bite into the inner circumferential surface 75c of the journal portion 75, limiting the relative rotation of the rotating member 51 and the gear 71 around the central axis Ax.

[0093] Next, the expansion member 39 is inserted into the hole 67. The expansion member 39 passes through the inside of the first inner circumferential surface 62c and is press-fitted into the inside of the second inner circumferential surface 62d. As a result, the expansion member 39 expands the protrusion 62 and fixes the protrusion 62 to the gear 71. In this way, the rotating member 51 and the gear 71 are connected to each other so as to be able to transmit power to each other.

[0094] In the brake system 10 according to the first embodiment described above, the gear 71 is configured to rotate around the central axis Ax, and is provided with a through hole 78 extending in the axial direction along the central axis Ax. The rotating member 51 has a threaded portion 61 provided with a male screw 61b, and a protruding portion 62 protruding from the threaded portion 61 in the rear direction Db along the central axis Ax and fitted into the through hole 78. A hole 67 is provided at an end of the protruding portion 62 in the rear direction Db. The housing 31 is provided with a cylinder 41. The piston 32 is disposed in the cylinder 41. The linear moving member 52 has a female screw 52b attached to the male screw 61b via a ball 53. The linear moving member 52 moves in the rear direction Db or in the forward direction Df opposite to the rear direction Db in response to the rotation of the rotating member 51, and pushes the piston 32 by moving in the forward direction Df. The motor 37 drives the rotating member 51 to rotate about the central axis Ax via the gear 71. The expansion member 39 is fitted into the hole 67 and expands the protrusion 62 so as to restrict the protrusion 62 from coming out of the through hole 78.

[0095] The expansion member 39 expands the protrusion 62, thereby preventing the protrusion 62 of the rotating member 51 from slipping out of the through hole 78 in the forward direction Df. Compared to a case in which the protrusion 62 is fixed to the through hole 78 by simple crimping or press-fitting, the electric cylinder device 21 can more reliably fix the protrusion 62 to the through hole 78 by the expansion member 39 that remains in the hole 67 even after manufacture. Therefore, the electric cylinder device 21 can prevent the rotating member 51 from coming off the gear 71.

[0096] The expansion member 39 expands a portion of the protruding portion 62 located inside the through hole 78. This causes the protruding portion 62 to be pressed against the gear 71 in the radial direction. Therefore, the frictional force between the protruding portion 62 and the gear 71 increases, and the rotating member 51 can rotate approximately integrally with the gear 71 around the central axis Ax. In other words, the electric cylinder device 21 can suppress the rotating member 51 and the gear 71 from rotating idly relative to each other around the central axis Ax.

[0097] The gear 71 has an inner peripheral surface 75c that forms a through hole 78. The protruding portion 62 has an outer peripheral surface 62a that faces the inner peripheral surface 75c. At least one of the inner peripheral surface 75c and the outer peripheral surface 62a is provided with a plurality of grooves 86, 96 that extend in the axial direction and are aligned around the central axis Ax. The plurality of grooves 86, 96 are located in a part of the inside of the through hole 78 in the axial direction. The plurality of grooves 86, 96 form a plurality of teeth 87, 97 on at least one of the inner peripheral surface 75c and the outer peripheral surface 62a. The teeth 97 provided on the inner peripheral surface 75c bite into the outer peripheral surface 62a, the teeth 87 provided on the outer peripheral surface 62a bite into the inner peripheral surface 75c, or the teeth 97 provided on the inner peripheral surface 75c and the teeth 87 provided on the outer peripheral surface 62a mesh with each other, so that the rotating member 51 can rotate approximately integrally with the gear 71 around the central axis Ax. Furthermore, in another part of the through hole 78 in the axial direction, the grooves 86, 96 are not provided, and for example, the inner peripheral surface 75c and the outer peripheral surface 62a can contact each other over a wider area. The expansion member 39 presses the outer peripheral surface 62a of the protrusion 62 against the inner peripheral surface 75c of the gear 71, increasing the frictional force between the inner peripheral surface 75c and the outer peripheral surface 62a. As described above, in one part of the through hole 78 in the axial direction, the rotating member 51 and the gear 71 are fixed to each other around the central axis Ax by the grooves 86, 96 (the teeth 87, 97), and in another part of the through hole 78 in the axial direction, the rotating member 51 and the gear 71 are fixed to each other in the axial direction and around the central axis Ax by the friction between the inner peripheral surface 75c (cylindrical region 91) and the outer peripheral surface 62a (cylindrical region 81). Therefore, the electric cylinder device 21 can more firmly integrate the rotating member 51 and the gear 71.

[0098] The grooves 96 extend from an end of the inner circumferential surface 75c in the rear direction Db in the forward direction Df and are spaced apart from an end of the through hole 78 in the forward direction Df. The grooves 86 extend from an end of the outer circumferential surface 62a in the rear direction Db in the forward direction Df and are spaced apart from an end of the through hole 78 in the forward direction Df. That is, the grooves 86, 96 are not provided between the end of the through hole 78 in the forward direction Df and the grooves 86, 96 (the teeth 87, 97). The protrusion 62 is inserted into the through hole 78 in the rear direction Db. In this case, the diameter of the cylindrical region 81, 91 between the end of the through hole 78 in the forward direction Df and the grooves 86, 96 is larger than the diameter of the rotation limiting region 82, 92. That is, the diameter of the cylindrical regions 81, 91 is increased between the end of the through hole 78 in the forward direction Df and the grooves 86, 96, and thus the contact area between the inner circumferential surface 75c and the outer circumferential surface 62a is increased. Therefore, the electric cylinder device 21 can more firmly integrate the rotating member 51 and the gear 71.

[0099] In the axial direction, the end of the protrusion 62 in the rear direction Db is located at the same position as the end of the through hole 78 in the rear direction Db, or is located between both ends of the through hole 78 in the axial direction. In other words, the protrusion 62 does not protrude in the rear direction Db from the end of the through hole 78 in the rear direction Db. This allows the rotating member 51 and the gear 71 to be made smaller.

[0100] The piston 32 reduces the volume of the fluid chamber 45 of the cylinder 41 by moving in the forward direction Df. The electric cylinder device 21 increases the pressure in the wheel cylinder 12 by reducing the volume of the fluid chamber 45. When the power supply to the motor 37 is lost, the piston 32 and the linear moving member 52 are pushed in the rear direction Db by the pressure of the wheel cylinder 12, and the linear moving member 52 may collide with another member. However, the expansion member 39 can expand the protruding portion 62, thereby preventing the protruding portion 62 of the rotating member 51 from coming out of the through hole 78 in the forward direction Df when the linear moving member 52 collides.

[0101] Fig. 4 is a cross-sectional view partially showing a rotating member 51 and a gear 71 according to a modified example of the first embodiment. The positional relationship between the cylindrical regions 81, 91 and the rotation limiting regions 82, 92 in the protruding portion 62 and the journal portion 75 is not limited to the aspect shown in Fig. 2, and may be, for example, the aspect shown in Fig. 4.

[0102] 4, the cylindrical regions 81, 91 may be disposed on the rear side, and the rotation limiting regions 82, 92 may be disposed on the front side. In this case, the rotation limiting region 82 of the protruding portion 62 is located between the cylindrical region 81 and the threaded portion 61, and the rotation limiting region 92 of the journal portion 75 is located between the cylindrical region 91 and the front surface 75a of the journal portion 75. In this case, the maximum diameter of the cylindrical region 81 of the protruding portion 62 is smaller than the minimum diameter of the rotation limiting region 92 of the journal portion 75.

[0103] In the embodiment of Fig. 4, the protrusion 62 has an inner circumferential surface 62e forming a hole 67, instead of the first inner circumferential surface 62c and the second inner circumferential surface 62d. The inner circumferential surface 62e is located on the opposite side of the cylindrical region 81. The diameter of the expansion member 39 is larger than the diameter of the inner circumferential surface 62e. The expansion member 39 expands the protrusion 62 and presses it against the cylindrical region 91 of the journal portion 75 so that the diameter of the cylindrical region 81 expands upon contact with the inner circumferential surface 62e, thereby increasing the frictional force between them.

[0104] Second Embodiment The second embodiment will be described below with reference to Fig. 5. In the following description of the embodiments, components having the same functions as components already described are given the same reference numerals as the components already described, and further description may be omitted. Also, components given the same reference numerals do not necessarily have all the same functions and properties, and may have different functions and properties according to each embodiment.

[0105] FIG. 5 is a cross-sectional view partially showing a rotating member 51 and a gear 71 according to the second embodiment. As shown in FIG. 5, in the second embodiment, the protrusion 62 has an outer peripheral surface 201 instead of the outer peripheral surface 62a. The outer peripheral surface 201 is substantially equal to the outer peripheral surface 62a, except for the points described below. The outer peripheral surface 201 of the protrusion 62 does not have a rotation limiting region 82. Therefore, substantially the entire area of ​​the outer peripheral surface 201 is the cylindrical region 81. In other words, the outer peripheral surface 201 is formed in a cylindrical shape.

[0106] In the second embodiment, the journal portion 75 has an inner peripheral surface 211 instead of the inner peripheral surface 75c. The inner peripheral surface 211 is substantially equal to the inner peripheral surface 75c, except for the points described below. The inner peripheral surface 211 of the journal portion 75 does not have a rotation limiting region 92. Therefore, substantially the entire area of ​​the inner peripheral surface 211 is the cylindrical region 91. In other words, the inner peripheral surface 211 is formed in a cylindrical shape. The protrusion 62 is press-fitted into the through hole 78, and the cylindrical region 81 of the protrusion 62 and the cylindrical region 91 of the journal portion 75 are in close contact with each other over substantially the entire area around the central axis Ax.

[0107] The protrusion 62 of the second embodiment has an inner circumferential surface 62e forming a hole 67, instead of the first inner circumferential surface 62c and the second inner circumferential surface 62d. The inner circumferential surface 62e is located opposite the cylindrical region 81. The diameter of the extension member 39 is larger than the diameter of the inner circumferential surface 62e.

[0108] In the brake system 10 of the second embodiment described above, the outer circumferential surface 201 is formed in a cylindrical shape. The inner circumferential surface 211 is formed in a cylindrical shape and contacts the outer circumferential surface 201 over the entire area around the central axis Ax. This increases the contact area between the inner circumferential surface 211 and the outer circumferential surface 201. Therefore, the electric cylinder device 21 can more firmly integrate the rotating member 51 and the gear 71.

[0109] (Third embodiment) The third embodiment will be described below with reference to Fig. 6. Fig. 6 is a cross-sectional view partially showing a rotating member 51 and a gear 71 according to the third embodiment. As shown in Fig. 6, in the third embodiment, the rotating member 51 has a protrusion 300 instead of the protrusion 62. The protrusion 300 is substantially the same as the protrusion 62, except for the points described below.

[0110] The protruding portion 300 is longer in the axial direction than the through hole 78. The protruding portion 300 has an inner portion 301 and an outer portion 302. The inner portion 301 and the outer portion 302 are aligned in the axial direction and are continuous with each other.

[0111] The internal portion 301 is located between the threaded portion 61 and the external portion 302. The internal portion 301 extends in the rear direction Db from the threaded portion 61 and is housed in the through hole 78. The external portion 302 extends in the rear direction Db from the internal portion 301 and protrudes in the rear direction Db from the through hole 78. That is, the external portion 302 is located outside the through hole 78.

[0112] In the third embodiment, the protruding portion 300 has an outer peripheral surface 201 instead of the outer peripheral surface 62a. The outer peripheral surface 201 does not have a rotation limiting region 82. The inner portion 301 and the outer portion 302 each have a part of the cylindrical region 81. Also, in the third embodiment, the bearing portion 75 has an inner peripheral surface 211 instead of the inner peripheral surface 75c. The inner peripheral surface 211 does not have a rotation limiting region 92.

[0113] The protruding portion 300 is press-fitted into the through hole 78. The cylindrical region 81 of the inner portion 301 and the cylindrical region 91 of the journal portion 75 are in close contact with each other over substantially the entire area around the central axis Ax. On the other hand, the cylindrical region 81 of the outer portion 302 is exposed outside the through hole 78.

[0114] The protruding portion 300 of the third embodiment has an inner circumferential surface 62e forming a hole 67, instead of the first inner circumferential surface 62c and the second inner circumferential surface 62d. The inner circumferential surface 62e is located at least on the opposite side to the cylindrical region 81 of the outer portion 302. A part of the inner circumferential surface 62e may be located on the opposite side to the cylindrical region 81 of the inner portion 301.

[0115] The expansion member 39 is fitted into the hole 67 and expands the external portion 302. By expanding the external portion 302, an interference portion 311 is provided in the cylindrical region 81 of the external portion 302. The diameter of the interference portion 311 is larger than the diameter of the cylindrical region 81 of the internal portion 301.

[0116] For example, the interference portion 311 is a step between the cylindrical region 81 of the inner portion 301 and the expanded cylindrical region 81 of the outer portion 302. The interference portion 311 may be the cylindrical region 81 of the outer portion 302 that has been expanded to have a substantially conical shape.

[0117] The interference portion 311 contacts the edge of the through hole 78, thereby restricting the protrusion 300 from slipping out of the through hole 78 in the forward direction Df. That is, the expansion member 39 expands the outer portion 302 of the protrusion 300 so as to restrict the protrusion 300 from slipping out of the through hole 78.

[0118] In the brake system 10 of the third embodiment described above, the expansion member 39 expands the external portion 302 of the protruding portion 300 that protrudes in the rear direction Db from the through hole 78. This allows the dimensions of the expansion member 39 and the protruding portion 300 to be set more loosely than when the expansion member 39 expands the portion of the protruding portion 300 that is located inside the through hole 78.

[0119] As an example, the electric cylinder device according to at least one embodiment described above includes: a rotation transmission member configured to rotate around a rotation axis and provided with a through hole extending in an axial direction along the rotation axis; a screw portion provided with a first screw thread; and a protrusion protruding from the screw portion in a first axial direction along the rotation axis and fitted into the through hole, wherein a hole is provided at an end of the protrusion in the first axial direction; a housing provided with a cylinder; a piston arranged in the cylinder; a ball; and a linear motion member having a second screw thread attached to the first screw thread via the ball, which moves in the first axial direction or a second axial direction opposite to the first axial direction in response to rotation of the rotating member and pushes the piston by moving in the second axial direction; a motor that drives the rotating member to rotate around the rotation axis via the rotation transmission member; and an expansion member that is fitted into the hole and expands the protrusion to restrict the protrusion from coming out of the through hole. Therefore, for example, when the supply of power to the motor is lost, the piston and the linear motion member are pushed in the first axial direction by the pressure of the cylinder. The linear motion member may collide with another member such as a rotation transmission member by moving in the first axial direction. In this case, the linear motion member pulls the rotating member in the second axial direction via the ball due to the reaction force of the collision. However, the expansion member can expand the protruding portion to prevent the protruding portion of the rotating member from coming out of the through hole in the second axial direction. Compared to a case in which the protruding portion is fixed to the through hole by crimping or press-fitting, the electric cylinder can more reliably fix the protruding portion to the through hole by the expansion member that remains in the hole even after manufacturing. Therefore, the electric cylinder device can prevent the rotating member from coming out of the rotation transmission member.

[0120] In the electric cylinder device, as one example, the expansion member expands a portion of the protrusion located inside the through hole. Thus, as one example, the protrusion is pressed radially against the rotation transmission member. Therefore, the frictional force between the protrusion and the rotation transmission member increases, and the rotating member can rotate approximately integrally with the rotation transmission member about the rotation axis. In other words, the electric cylinder device can suppress the rotating member and the rotation transmission member from rotating idly relative to each other about the rotation axis.

[0121] In the electric cylinder device, as an example, the rotation transmission member has an inner surface forming the through hole, the protrusion has an outer surface facing the inner surface, and at least one of the inner surface and the outer surface is provided with a plurality of grooves each extending in the axial direction and aligned around the rotation axis, and the plurality of grooves are located in a part of the inside of the through hole in the axial direction. Thus, as an example, a plurality of teeth are formed on at least one of the inner surface and the outer surface by the plurality of grooves. The teeth provided on the inner surface bite into the outer surface, the teeth provided on the outer surface bite into the inner surface, or the teeth provided on the inner surface and the teeth provided on the outer surface mesh with each other, so that the rotating member can rotate about the rotation axis substantially integrally with the rotation transmission member. Furthermore, in another part of the through hole in the axial direction, no groove is provided, and for example, the inner surface and the outer surface can contact each other over a wider area. The expansion member presses the outer surface of the protrusion against the inner surface of the rotation transmission member, increasing the frictional force between the inner surface and the outer surface. As described above, in one part of the through hole in the axial direction, the rotating member and the rotation transmission member are fixed to each other around the rotation axis by the grooves (teeth), and in another part of the through hole in the axial direction, the rotating member and the rotation transmission member are fixed to each other in the axial direction and around the rotation axis by friction between the inner and outer surfaces. Therefore, the electric cylinder device can more firmly integrate the rotating member and the rotation transmission member.

[0122] In the above electric cylinder device, as an example, when the plurality of grooves are provided on the inner surface, the plurality of grooves extend from an end of the inner surface in the first axial direction in the second axial direction and are spaced apart from an end of the through hole in the second axial direction, and when the plurality of grooves are provided on the outer surface, the plurality of grooves extend from an end of the outer surface in the first axial direction in the second axial direction and are spaced apart from an end of the through hole in the second axial direction. Thus, as an example, no groove is provided between an end of the through hole in the second axial direction and the plurality of grooves (the plurality of teeth). The protruding portion is inserted into the through hole in the first axial direction. In this case, the diameters of the inner surface and the outer surface between the end of the through hole in the second axial direction and the plurality of grooves (the plurality of teeth) are larger than the diameters of the inner surface and the outer surface on which the plurality of grooves are provided. That is, the diameter of the inner surface and the outer surface is larger between the end of the through hole in the second axial direction and the plurality of grooves (the plurality of teeth), and thus the contact area between the inner surface and the outer surface is larger. Therefore, the electric cylinder device can more firmly integrate the rotating member and the rotation transmission member.

[0123] The brake fluid pressure control device according to at least one embodiment described above includes, as an example, the electric cylinder device connected to a wheel cylinder, and the piston reduces the volume of the fluid chamber of the cylinder by moving in the second axial direction, and the electric cylinder device can increase the pressure of the wheel cylinder by reducing the volume of the fluid chamber. Therefore, as an example, when the power supply to the motor is lost, the piston and the linear moving member are pushed in the first axial direction by the pressure of the wheel cylinder, and the linear moving member may collide with another member. However, the expansion member can expand the protruding portion to prevent the protruding portion of the rotating member from coming out of the through hole in the second axial direction when the linear moving member collides.

[0124] Although the embodiments of the present invention have been illustrated above, the above-mentioned embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The above-mentioned embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the gist of the invention. In addition, the configurations and shapes of each embodiment and each modification can be partially replaced and implemented. [Explanation of symbols]

[0125] 11...brake fluid pressure control device, 12...wheel cylinder, 21...electric cylinder device, 31...housing, 32...piston, 37...motor, 39...expansion member, 41...cylinder, 45...fluid chamber, 51...rotating member, 52...linear member, 52b...female thread (second thread), 61...threaded portion, 61b...male thread (first thread), 62,300...protrusion, 62a...outer peripheral surface (outer surface), 67...hole, 71...gear (rotation transmission member), 75c...inner peripheral surface (inner surface), 78...through hole, 86,96...groove, Ax...central axis (rotation axis), Db...rearward (first axial direction), Df...forward (second axial direction).

Claims

1. A rotation transmission member configured to rotate around a rotation axis and having a through hole extending in an axial direction along the rotation axis; a rotating member including a threaded portion having a first thread and a protruding portion protruding from the threaded portion in a first axial direction along the rotating shaft and fitted into the through hole, the protruding portion having a hole at an end portion in the first axial direction; a housing provided with a cylinder; A piston disposed in the cylinder; With the ball a linear motion member having a second screw thread attached to the first screw thread via the ball, moving in the first axial direction or a second axial direction opposite to the first axial direction in response to rotation of the rotating member, and pushing the piston by moving in the second axial direction; a motor that rotates the rotating member about the rotation shaft via the rotation transmission member; an expansion member that is fitted into the hole and expands the protrusion so as to restrict the protrusion from slipping out of the through hole; An electric cylinder device comprising:

2. The expansion member expands a portion of the protrusion located inside the through hole. The electric cylinder device according to claim 1.

3. the rotation transmission member has an inner surface that forms the through hole, The protrusion has an outer surface facing the inner surface, At least one of the inner surface and the outer surface is provided with a plurality of grooves each extending in the axial direction and aligned around the rotation axis, The plurality of grooves are located in a portion of the interior of the through hole in the axial direction. The electric cylinder device according to claim 2.

4. When the plurality of grooves are provided on the inner surface, the plurality of grooves extend in the second axial direction from an end of the inner surface in the first axial direction and are spaced apart from an end of the through hole in the second axial direction; When the plurality of grooves are provided on the outer surface, the plurality of grooves extend in the second axial direction from an end of the outer surface in the first axial direction and are spaced apart from an end of the through hole in the second axial direction. The electric cylinder device according to claim 3.

5. 5. The electric cylinder device according to claim 1, which is connected to a wheel cylinder. Equipped with The piston reduces a volume of a fluid chamber of the cylinder by moving in the second axial direction, The electric cylinder device is capable of increasing the pressure in the wheel cylinder by reducing the volume of the fluid chamber. Brake fluid pressure control device.

Images