electric actuator

Abstract

The electric actuator (20) includes: a motor (22) having a rotatable output shaft (22b) and a bearing (22c) for holding the output shaft (22b); a worm (24) mounted on the output shaft (22b); a worm wheel (35) meshing with the worm (24); and a force applying portion (31) for applying force to the output shaft (22b). When viewed from the direction in which the axis (A) of the worm wheel (35) extends, the force applying portion (31) applies force to the output shaft (22b) in a direction (B2) in which the worm (24) approaches the worm wheel (35) and in a direction (B1) in which the worm (24) moves away from the worm wheel (35), that is, in an approaching / moving direction (B).

Description

Technical Field

[0001] The present invention relates to electric actuators. Background Art

[0002] An electric steering lock device is known, which locks and unlocks the steering shaft of a vehicle by the action of a motor. The electric steering lock device includes an electric actuator, which includes a motor, a worm mounted on an output shaft of the motor, and a worm wheel meshing with the worm. The motor includes a bearing that rotatably holds the base end side of the output shaft, and lubricating oil is filled between the output shaft and the bearing.

[0003] In the electric actuator, due to the meshing of the worm and the worm wheel, the output shaft moves (vibration rotation) in the direction of approaching / leaving the worm wheel (the approaching direction and the leaving direction). Patent document 1 discloses an electric actuator including a mechanism for suppressing the vibration rotation of the output shaft. The mechanism of the electric actuator includes an O-ring mounted on the front end of the output shaft of the motor, and the O-ring is arranged on the bearing portion of the housing.

[0004] [Prior art literature]

[0005] [Patent Document]

[0006] Patent Document 1: Japanese Patent Application Publication No. 2006-67694 Summary of the invention

[0007] [Problems to be solved by the invention]

[0008] In the mechanism of Patent Document 1, the output shaft cannot be adequately held (constrained) by the O-ring when the load (rotational resistance) of the motor is taken into consideration. Therefore, the vibration rotation (reverberation) of the output shaft of the motor cannot be effectively suppressed.

[0009] In addition, when the oil in the motor bearings is depleted (de-oiled) due to deterioration over time, the electric actuator cannot mitigate the collision between the output shaft and the bearings, so abnormal noise is generated in the motor bearings. In the mechanism of Patent Document 1, it is impossible to suppress the abnormal noise generated in the motor bearings due to the de-oiling.

[0010] An object of the present invention is to provide an electric actuator that can effectively suppress vibration rotation of an output shaft of a motor and generation of abnormal noise due to oil loss.

[0011] [Technical solutions for solving technical problems]

[0012] One embodiment of the present invention provides an electric actuator, comprising: a motor having a rotatable output shaft and a bearing for rotatably holding the output shaft; a worm mounted on the output shaft; a worm wheel meshing with the worm; and a force applying portion for applying force to the output shaft in a direction in which the worm approaches and moves away from the worm wheel, i.e., in an approaching / moving direction, as viewed from a direction in which an axis of the worm wheel extends.

[0013] Effects of the Invention

[0014] In the electric actuator of the present invention, the vibratory rotation of the output shaft can be effectively suppressed by the force applying portion that applies force to the output shaft in the approaching / separating direction relative to the worm wheel. In addition, since the output shaft can be held by the force applying portion so as to interfere with the fixed position of the bearing, even if oil loss occurs, the generation of abnormal noise caused by the collision between the output shaft of the motor and the bearing can be effectively suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a perspective view of an electric steering lock device including an electric actuator according to a first embodiment of the present invention.

[0016] Figure 2 yes Figure 1 A cross-sectional view of an electric steering lock device.

[0017] Figure 3 Observed from one side Figure 1 An exploded perspective view of an electric steering lock device.

[0018] Figure 4 It is a three-dimensional view of the shell body.

[0019] Figure 5 yes Figure 1 A partially exploded perspective view of an electric steering lock device.

[0020] Figure 6 yes Figure 8 Partial cross-sectional view of the bottom surface.

[0021] Figure 7 yes Figure 1 A partial cross-sectional view of an electric steering lock device.

[0022] Figure 8 yes Figure 1 A partial perspective view of an electric steering lock device.

[0023] Fig. 9 yes Figure 8 Exploded three-dimensional diagram.

[0024] Fig.10It is a partially exploded perspective view of an electric steering lock device according to a second embodiment.

[0025] Fig.11 yes Fig.10 A partial bottom view of the electric steering lock device.

[0026] Fig.12 yes Fig.10 A partial cross-sectional view of an electric steering lock device.

[0027] Fig.13 yes Fig.10 A partial perspective view of an electric steering lock device.

[0028] Fig.14 It is a partially exploded perspective view of an electric steering lock device according to a third embodiment.

[0029] Fig.15 yes Fig.14 A partial bottom view of the electric steering lock device.

[0030] Fig.16 yes Fig.14 A partial cross-sectional view of an electric steering lock device.

[0031] Fig.17 yes Fig.14 A partial perspective view of an electric steering lock device. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0033] (First embodiment)

[0034] Figure 1 and Figure 2 FIG. 1 shows an electric steering lock device 10 for a vehicle including an electric actuator 20 according to a first embodiment of the present invention. In the figure, the X direction corresponds to the vehicle width direction, the Y direction corresponds to the vehicle length direction, and the Z direction roughly corresponds to the vehicle height direction. In the following description, the terms "upward", "downward", "upper part", and "lower part" are all used with respect to the steering lock device 10. Figure 1 and Figure 2 That is, these terms are used in such a manner that the direction of the arrow in the Z direction is upward and the direction opposite to it is downward.

[0035] (Overview of Steering Lock Device)

[0036] The housing 12 of the steering lock device 10 is fixed to a housing 12 that accommodates a Figure 1 The steering shaft 1 shown is a cylindrical steering column (not shown). Figure 1 and Figure 2 The steering lock device 10 includes a lock bolt (lock member) 16 that is driven by an electric actuator 20 to move forward and backward.

[0037] The locking bolt 16 is in the locked position ( Figure 1 The locking bolt 16 is a bolt that moves linearly between a locked position (as shown in the figure) and an unlocked position that is retracted into the housing 12. In the locked position, the front end of the locking bolt 16 is disposed between a pair of adjacent teeth 2a of the collar 2 fixed to the steering shaft 1 (locking groove). In the locked position, the steering shaft 1 is prevented from rotating due to interference between the front end of the locking bolt 16 and the teeth 2a. In the unlocked position, the steering shaft 1 is allowed to rotate because the front end of the locking bolt 16 is retracted from between the pair of teeth 2a.

[0038] Reference Figure 2 and Figure 3 The housing 12 includes a housing body 13 and a housing cover 14. In the present embodiment, the housing body 13 and the housing cover 14 are made of magnesium or zinc. However, the housing body 13 and the housing cover 14 may also be made of resin. Figure 1 ) are embedded in holes 13a and 14a provided in the housing body 13 and the housing cover 14, and the housing cover 14 is fixed to the housing body 13.

[0039] like Figure 2 and Figure 3 As shown, the electric actuator 20 and the transmission mechanism 40 are accommodated in the interior of the housing 12, that is, in the space defined by the housing body 13 and the housing cover 14. The transmission mechanism 40 converts the rotation output of the electric actuator 20, more specifically, the rotation of the worm wheel 35 described later, into the linear forward and backward movement of the lock bolt 16.

[0040] The housing body 13 is provided with a structure for arranging the electric actuator 20 and the transmission mechanism 40. Specifically, Figure 4 As shown, a partition wall 13c is erected on the top wall 13b of the housing body 13, and the motor body configuration part 13d and the output shaft configuration part 13e are defined by the partition wall 13c. The motor body configuration part 13d and the output shaft configuration part 13e are spatially connected. The output shaft configuration part 13e includes a worm configuration part 13f and a bearing configuration part 13g. In addition, a cylindrical wall 13h is erected on the top wall 13b of the housing body 13 adjacent to the partition wall 13c, and the transmission mechanism configuration part 13i is defined by the cylindrical wall 13h. The cylindrical wall 13h is partially integrated with the partition wall 13c, and the transmission mechanism configuration part 13i and the worm configuration part 13f are spatially connected. In the housing body 13, a through hole 13j is provided that penetrates the top wall 13b in a manner located inside the cylindrical wall 13h.

[0041] Reference Figure 2 The housing cover 14 is provided with a rotation retaining portion 14b formed of a circular shallow depression at a position opposite to the cylindrical wall 13h. The rotation retaining portion 14b includes a positioning protrusion 14c for positioning one end of a spring 44 described later.

[0042] (Overview of Electric Actuator)

[0043] like Figure 3 and Figures 5 to 9 As shown, the electric actuator 20 includes a rotary motor 22, a worm 24, a bearing 27, and a worm wheel 35. The worm wheel 35 also functions as a component of the transmission mechanism 40.

[0044] The motor 22 includes a motor body 22a that houses a rotor and a stator, and an output shaft 22b that protrudes from the motor body 22a. Figure 6 The motor body 22a includes a bearing 22c that rotatably holds the base end side of the output shaft 22b. The bearing 22c includes a through hole 22d that allows the output shaft 22b to protrude. The diameter R1 of the through hole 22d is larger than the diameter R2 of the output shaft 22b. The gap is filled with oil as a lubricant to mitigate the collision between the output shaft 22b and the bearing 22c (the peripheral wall of the through hole 22d). The output shaft 22b is mechanically connected to the rotor and rotates together with the rotor when the motor 22 is powered (driven). Both ends of the output shaft 22b protrude from the motor body 22a.

[0045] The worm 24 is fixed to one end of the output shaft 22b. The worm 24 includes a body 24a through which the output shaft 22b penetrates, and a spiral tooth portion 24b formed on the outer peripheral surface of the body 24a.

[0046] The motor body 22a is arranged in the motor body arrangement portion 13d, the output shaft 22b is arranged in the output shaft arrangement portion 13e, and the worm 24 is arranged in the worm arrangement portion 13f.

[0047] Reference Figure 7 In the output shaft 22b of the motor 22, the front end portion protruding from the worm 24 is rotatably held by the bearing portion 27. The bearing portion 27 is provided in the cover 26, and the cover 26 covers the output shaft configuration portion 13e, the worm configuration portion 13f, the bearing configuration portion 13g, and the transmission mechanism configuration portion 13i. In addition, the specific structure of the bearing portion 27 will be described in detail later.

[0048] By covering the gear portion 35b of the worm wheel 35, the cover 26 prevents the lubricant (grease) applied to the gear portion 35b from scattering around. Figure 8 and Fig. 9The cover 26 is provided with: a support portion 26 a that supports the output shaft 22 b closer to the base end side than the worm 24 ; and a through hole 26 b that allows the cylindrical portion 35 c of the worm wheel 35 to penetrate.

[0049] like Figure 2 , Figure 8 and Fig. 9 As shown, the worm wheel 35 is generally a cylindrical body with both ends open. The worm wheel 35 of this embodiment is made of resin. The worm wheel 35 includes: a cylindrical gear portion 35b, which is formed with helical teeth 35a on the outer periphery; and a cylindrical portion 35c, which protrudes downward from the gear portion 35b. The helical teeth 35a of the gear portion 35b are meshed with the tooth portion 24b of the worm 24. Since the cylindrical portion 35c passes through the through hole 26b of the cover 26 and is held by the rotation holding portion 14b of the housing cover 14, the worm wheel 35 is rotatably held in the housing 12.

[0050] When the output shaft 22b of the motor 22 rotates, the worm 24 fixed to the output shaft 22b rotates. The rotation of the output shaft 22b is transmitted to the worm wheel 35 by meshing the teeth 24b of the worm 24 with the helical teeth 35a of the worm wheel 35, and the worm wheel 35 rotates about the axis A.

[0051] (Overview of the delivery organization)

[0052] like Figure 2 and Figure 3 As shown, the transmission mechanism 40 includes a worm gear 35 and a slider 42 .

[0053] A spiral thread groove 35 d is formed on the inner surface of the cylindrical portion 35 c of the worm wheel 35 .

[0054] The slider 42 includes an insertion portion 42 a disposed in the worm wheel 35 , and a holding portion 42 c protruding upward from the worm wheel 35 .

[0055] The insertion portion 42a is roughly cylindrical, and a threaded protrusion 42b that meshes with the thread groove 35d is formed on the outer peripheral surface of the lower portion. The slider 42 is urged upward by a spring 44 disposed in the insertion portion 42a. One end of the spring 44 is positioned at the positioning protrusion 14c of the housing cover 14, and the other end of the spring 44 abuts against the inner wall of the insertion portion 42a.

[0056] The holding portion 42c is in the shape of a tray with an open upper end, and contains the base end side of the locking bolt 16. The locking bolt 16 is mechanically connected to the slider 42 by inserting the connecting pin 45 arranged in the holding portion 42c into the connecting hole 16a of the locking bolt 16 in a radially penetrating manner. The connecting hole 16a of the locking bolt 16 is composed of an ellipse extending in the up-down direction. As a result, the locking bolt 16 is configured to be able to move forward and backward relative to the holding portion 42c (connecting pin 45). The locking bolt 16 is urged upward by the spring 46 arranged in the holding portion 42c. One end of the spring 46 abuts against the lower end of the inner wall of the holding portion 42c, and the other end of the spring 46 abuts against the lower end of the locking bolt 16.

[0057] The slider 42 has a stopper 42d at its upper end to limit the slider 42 from rotating relative to the housing body 13. The stopper 42d is fitted into a guide groove 13k provided in the housing body 13. The guide groove 13k extends in the vertical direction along the axis A of the worm wheel 35.

[0058] When the worm wheel 35 rotates, the thread groove 35d rotates relative to the thread protrusion 42b of the slider 42 whose rotation is restricted. As a result, the slider 42 moves linearly in a direction corresponding to the rotation axis direction of the worm wheel 35. Through this linear motion, the locking bolt 16 inserted through the insertion hole 13j moves forward and backward. In this way, the assembly consisting of the slider 42 and the locking bolt 16 connected thereto can only move linearly in the up and down direction, and unlike the worm wheel 35, it does not rotate.

[0059] When the locking bolt 16 is inserted or removed and the front end of the locking bolt 16 is not located between the pair of teeth 2a of the collar 2, the front end of the locking bolt 16 abuts against the outer end of one of the teeth 2a, so the insertion or removal of the locking bolt 16 is stopped midway. In this state, the steering shaft 1 is rotated, and when the locking bolt 16 is located between the pair of teeth 2a of the collar 2, the locking bolt 16 is inserted or removed by the force of the spring 46 and is locked between the pair of teeth 2a.

[0060] When the lock bolt 16 is retracted, the side surface of the tooth portion 2a may be strongly pressed against the lock bolt 16 due to the static steering torque of the steering shaft 1. In this case, due to the friction force, an excessive force greater than that in normal operation is applied to the electric actuator 20 and the transmission mechanism 40 that operate the lock bolt 16.

[0061] Reference Figure 2A control board 50 is disposed in the housing 12. The control board 50 is provided with electrical components and electronic components for realizing various functions including supplying power to the motor 22, controlling the operation of the motor 22, and detecting the forward and backward positions of the locking bolt 16. In addition, the control board 50 is provided with a connector 51 electrically connected to the ECU (Electronic Control Unit) of the vehicle. Figure 3 The connection port of the connector 51 is exposed to the outside through the through hole 14 d of the housing cover 14 .

[0062] (Bearing section overview)

[0063] like Figures 5 to 9 As shown, the bearing 27 is integrally provided on the resin cover 26 (integral structure) in a manner protruding toward the output shaft 22b. By arranging the cover 26 on the housing body 13, the bearing 27 is arranged in the bearing arrangement portion 13g and rotatably holds the front end of the output shaft 22b of the motor 22.

[0064] The bearing portion 27 includes: first to third limiting portions 28 to 30 that limit the movement of the output shaft 22b; and a force applying portion 31 that applies force to the output shaft 22b. The force applying portion 31 applies force to the output shaft 22b in the approaching / separating direction B relative to the worm wheel 35. The output shaft 22b of this embodiment is configured to extend in the X direction relative to the housing 12. Figure 6 As shown, the so-called approach / departure direction B means the direction B1 in which the worm 24 (output shaft 22b) moves away from the worm wheel 35 and the direction B2 in which the worm 24 (output shaft 22b) moves toward the worm wheel 35. When viewed from the direction in which the axis A of the worm wheel 35 extends, the direction is intersecting with the output shaft 22b. In the present embodiment, the direction is equivalent to the Y direction.

[0065] The first restricting portion 28 is composed of a quadrilateral plate extending along the YZ plane. Figure 6 The limiting portion 28 is provided at a position opposite to the axial direction (X direction) of the output shaft 22b relative to the front end of the output shaft 22b. A predetermined interval I1 is set between the limiting portion 28 and the front end of the output shaft 22b. The interval I1 is set to a distance that can prevent excessive movement of the output shaft 22b in the X direction when a force in the thrust direction acts on the output shaft 22b due to the drive of the motor 22. The thickness of the limiting portion 28 in the X direction is set to a dimension that will not deform even if the output shaft 22b abuts (collides). That is, the limiting portion 28 has a rigidity that can limit the movement of the output shaft 22b in the X direction.

[0066] The second limiting portion 29 is composed of a quadrilateral plate extending along the XZ plane. The limiting portion 29 is provided at a position adjacent to the opposite side of the worm wheel 35 relative to the output shaft 22b in the approach / separation direction B. The total height of the limiting portion 29 in the Z direction is greater than the diameter R2 of the output shaft 22b and is less than the total height of the first limiting portion 28 in the Z direction (see Figure 8 ). Reference Figure 6 One end of the limiting portion 29 in the X direction is continuous with the first limiting portion 28, and the other end of the limiting portion 29 in the X direction is opposite to one end of the worm 24 at a predetermined interval I2. The interval I2 is set larger than the interval I1 between the first limiting portion 28 and the output shaft 22b. That is, it is configured so that the worm 24 does not interfere with the limiting portion 29 even if the output shaft 22b moves in the X direction.

[0067] The thickness of the second limiting portion 29 in the Y direction is set to a dimension such that when a force in the Y direction acts on the output shaft 22b due to the drive of the motor 22, even if the output shaft 22b moves in the direction (first direction) B1 away from the worm wheel 35 and presses the second limiting portion 29, it will not be deformed. That is, the limiting portion 29 has a rigidity that can prevent (limit) the movement of the output shaft 22b in the Y direction. A predetermined interval is set between the limiting portion 29 and the output shaft 22b. The interval is set to a distance such that when an excessive force in the radial direction acts on the output shaft 22b due to the drive of the motor 22, the excessive movement of the output shaft 22b in the Y direction can be prevented. That is, as long as the excessive force does not act in the radial direction, the output shaft 22b will not abut against the limiting portion 29. The support surface 29a of the limiting portion 29 abutted by the output shaft 22b is a flat surface without concave and convex, and is in line contact with the outer peripheral surface of the slightly deflected output shaft 22b.

[0068] The third restricting portion 30 is formed of a protruding portion extending along the XY plane and protruding from the cover 26 in an L-shaped plan view. Figure 6 The first limiting portion 28 is continuous with the first side of the limiting portion 30, and the second limiting portion 29 is continuous with the second side of the limiting portion 30. Figure 7 The thickness of the limiting portion 30 in the Z direction is set to a size that does not deform when the output shaft 22b abuts (collides) with it, and is positioned to be spaced apart from the output shaft 22b by a predetermined interval. The interval is set to a distance that can prevent the output shaft 22b from excessively moving in the Z direction when excessive force in the radial direction acts on the output shaft 22b due to the drive of the motor 22. That is, since the output shaft 22b of the motor 22 does not abut against the second limiting portion 29 and the third limiting portion 30 during normal operation, the rotation resistance of the output shaft 22b is not increased.

[0069] The force applying portion 31 is composed of a quadrilateral plate extending along the XZ plane. The force applying portion 31 is provided at a position adjacent to the worm wheel 35 side of the output shaft 22b. The force applying portion 31 is arranged to be opposite to the second limiting portion 29 across the output shaft 22b in the approaching / separating direction B and parallel to the limiting portion 29. The force applying portion 31 protrudes from the cover 26 and is positioned to be spaced apart from the third limiting portion 30 in the X direction and the Y direction.

[0070] The contact surface 31a of the force applying portion 31 that contacts the output shaft 22b is a flat surface without any unevenness. Figure 6 As shown by the dotted line, the contact surface 31a is positioned at a predetermined interval I3 relative to the support surface 29a of the second limiting portion 29 when the output shaft 22b is not held. The interval I3 is smaller than the diameter R2 of the output shaft 22b. Therefore, since the output shaft 22b is arranged between the second limiting portion 29, the force-applying portion 31 is deformed in the direction (second direction) B2 approaching the worm wheel 35, and the output shaft 22b is forced in the direction B1 away from the worm wheel 35 due to the elastic restoring force. The so-called deformation here means that the base of the force-applying portion 31 located on the cover 26 side is bent, and the force-applying portion 31 as a whole maintains a flat plate shape in line contact with the output shaft 22b.

[0071] The thickness of the force applying portion 31 in the Y direction is thinner than the thickness of the restricting portions 28 to 30 and is of a dimension that can be elastically deformed in the approaching / separating direction B. By setting this thickness, the force of the force applying portion 31 can be adjusted. In the present embodiment, the force is set to be such that the output shaft 22b can be held so that the output shaft 22b interferes with the fixed position of the bearing 22c within a range that does not hinder the rotation of the output shaft 22b, and the interference is maintained.

[0072] The holding position of the output shaft 22b held by the force applying portion 31 is a position where the output shaft 22b of the motor 22 interferes with the fixed position of the bearing 22c. In addition, the holding position is set to a position where a predetermined gap is formed between the front end of the tooth portion 24b of the worm 24 and the gear portion 35b of the worm wheel 35, and between the front end of the helical teeth 35a of the worm wheel 35 and the main body 24a of the worm 24. The gap is set within a range that can ensure the meshing of the tooth portion 24b of the worm 24 and the helical teeth 35a of the worm wheel 35.

[0073] (Function of the bearing)

[0074] By disposing the cover 26 on the housing body 13 in which the motor 22 including the worm 24 and the transmission mechanism 40 are disposed, the bearing portion 27 is disposed in the bearing portion disposing portion 13g. By disposing the cover 26, the bearing portion 27 is fixed to the housing body 13, and the output shaft 22b is held between the second limiting portion 29 and the force applying portion 31. At this time, the force applying portion 31 will bend in the direction B2 approaching the worm wheel 35, and due to this bending, the output shaft 22b is elastically urged in the direction B1 away from the worm wheel 35. As a result, the output shaft 22b is maintained in a state of interfering with the fixed position of the bearing 22c. In addition, a predetermined gap is ensured between the tooth portion 24b of the worm 24 and the helical teeth 35a of the worm wheel 35 within a range that can ensure meshing.

[0075] Reference Figure 7 Since the force is applied only in the first direction B1 by the force applying portion 31, the radial position of the output shaft 22b is not completely positioned. Figure 6 , the axial position of the output shaft 22b of the motor 22 is not completely positioned. That is, there is essentially unavoidable play in the radial and axial positions of the output shaft 22b.

[0076] When the motor 22 is driven and the output shaft 22b moves (vibrates and rotates) in the approach / separate direction B due to the meshing of the tooth portion 24b of the worm 24 and the helical teeth 35a of the worm wheel 35, there is a case where the output shaft 22b collides with the bearing 22c and generates abnormal noise. However, if elastic non-deformable limiting portions are provided on both sides of the output shaft 22b in the approach / separate direction B, the vibrating rotation of the output shaft 22b and the generation of abnormal noise caused by it can be suppressed. However, in this case, due to the force acting on the output shaft 22b in the approach / separate direction B, the rotation impedance of the output shaft 22b becomes excessive, so the load applied to the motor 22 increases.

[0077] In contrast, in the electric actuator 20 of the present embodiment, by applying force to the front end of the output shaft 22b using the force applying portion 31, the movement of the output shaft 22b toward the direction B2 approaching the worm wheel 35 is allowed and suppressed within a predetermined range. Therefore, it is possible to effectively suppress the vibratory rotation of the output shaft 22b in the approach / separation direction B while ensuring the meshing of the worm 24 and the worm wheel 35. In addition, the second limiting portion 29 and the force applying portion 30 can be used to hold (maintain) the output shaft 22b at a predetermined position that interferes with the bearing 22c. As a result, the collision sound caused by repeated interference and separation between the output shaft 22b and the bearing 22c can be reduced. As a result, even if the bearing 22c is de-oiled, the generation of abnormal noise caused by the collision between the output shaft 22b and the bearing 22c can be effectively suppressed.

[0078] Since the front end of the output shaft 22b is urged toward the direction B1 away from the worm wheel 35 by the urging portion 31, a predetermined gap can be ensured between the tooth portion 24b of the worm 24 and the helical teeth 35a of the worm wheel 35. Therefore, since the friction resistance between the worm 24 and the worm wheel 35 can be reduced, the worm 24 can be smoothly rotated. As a result, the load applied to the motor 22 can be effectively reduced.

[0079] When the motor 22 is driven, the second limiting portion 29 opposite to the force applying portion 31 can be used to limit the inclination of the output shaft 22b caused by the reaction force from the worm wheel 35. That is, the inclination of the output shaft 22b is limited by the second limiting portion 29, and the vibration rotation of the output shaft 22b is suppressed by the force applying portion 31. In addition, the movement of the output shaft 22b in the X direction can be limited by the first limiting portion 28, and the movement of the output shaft 22b in the Z direction can be limited by the third limiting portion 30. Therefore, since the output shaft 22b can be reliably maintained at a predetermined position, even if the bearing 22c is de-oiled, the generation of abnormal noise caused by the collision between the output shaft 22b and the bearing 22c can be effectively suppressed.

[0080] Since the first to third restricting portions 28 to 30 and the biasing portion 31 are integrally provided on the single cover 26, the number of components constituting the electric actuator 20 can be reduced. Furthermore, since the bearing portion 27 and the biasing portion 31 can be easily arranged at a predetermined position by mounting the cover 26, the assemblability of the electric steering lock device 10 including the electric actuator 20 can be improved.

[0081] (Second embodiment)

[0082] Fig.10 and Fig.11 The electric steering lock device 10 including the electric actuator 20 of the second embodiment is shown. In the second embodiment, the bearing portion 27 is different from the first embodiment in that it includes a biasing member (biasing portion) 55 separate from the cover 26, and the front end of the output shaft 22b of the motor 22 is biased in the approaching / separating direction B by the biasing member 55.

[0083] The housing body 13 is provided with a bearing placement portion (placement portion) 13g similarly to the first embodiment. Fig.12 The bearing configuration portion 13g is formed by a groove that is recessed upward in the Z direction. Fig.11 The entire length of the bearing arrangement portion 13 g in the X direction is a dimension capable of arranging the urging member 55 and the first restricting portion 28 .

[0084] Reference Fig.10The cover 26 is provided with a first limiting portion 28 and a third limiting portion 30, but the second limiting portion 29 shown in the first embodiment is not provided. The first limiting portion 28 is opposite to the front end of the output shaft 22b in the X direction and has a dimension extending from one end to the other end of the bearing portion configuration portion 13g in the Y direction. Fig.12 The third restricting portion 30 is located on the Z-direction lower side of the urging member 55. The first restricting portion 28 and the third restricting portion 30 also function as components for preventing the independent urging member 55 from falling off.

[0085] like Figure 11 to Figure 13 As shown, the urging member 55 is arranged on the motor body 22a side of the bearing portion arrangement portion 13g in a manner adjacent to the first restricting portion 28. The urging member 55 is composed of a metal leaf spring, and includes: a first urging portion 56A that urges the output shaft 22b in a direction B1 away from the worm wheel 35; and a second urging portion 56B that urges the output shaft 22b in a direction B2 approaching the worm wheel 35. These are linearly symmetrical shapes, and by being arranged in the bearing portion arrangement portion 13g, one constitutes the first urging portion 56A, and the other constitutes the second urging portion 56B.

[0086] like Fig.12 and Fig.13 As shown, the urging member 55 includes: a continuous portion 55a, which is arranged along the bottom surface 13m of the bearing portion arrangement portion 13g; and a pair of side portions 55b, which are continuous with both sides of the continuous portion 55a. The pair of side portions 55b are bent in the same direction relative to the continuous portion 55a and are arranged along a pair of side surfaces 13n of the bearing portion arrangement portion 13g.

[0087] The pair of urging parts 56A and 56B are respectively composed of an inclined part 55c, a holding part 55d, and a tapered part 55e formed on the urging member 55. By setting the forming material and thickness of the urging member 55, the urging force of the urging parts 56A and 56B is set to a magnitude that can hold the output shaft 22b at a predetermined position within a range that does not hinder the rotation of the output shaft 22b.

[0088] The inclined portion 55c is continuous with the front end of the side portion 55b. As the continuous portion 55a is separated, the pair of inclined portions 55c are gradually approached and bent inwardly relative to the side portion 55b along the Y direction. Since the inclined portion 55c is bent outwardly along the Y direction with the bent portion between the side portion 55b and the inclined portion 55c as a fulcrum, an elastic force is generated on the force applying portions 56A and 56B.

[0089] The retaining portion 55d is continuous with the front end of the inclined portion 55c, and is bent toward the inclined portion 55c in a manner extending in a direction orthogonal to the approach / departure direction B (Y direction). That is, a pair of retaining portions 55d are positioned parallel and extend along the XZ plane. The retaining portion 55d is in line contact with the output shaft 22b, and the output shaft 22b is retained between the pair of retaining portions 55d. In a state where the output shaft 22b is not retained, the spacing between the pair of retaining portions 55d is smaller than the diameter of the output shaft 22b. The total length of the retaining portion 55d in the Z direction is formed to be larger than the diameter of the output shaft 22b, and is capable of retaining the size of the output shaft 22b configured in the housing body 13.

[0090] In addition, if Fig.12 As shown, in a state where the continuous portion 55a of the urging member 55 is in contact with the bottom surface 13m of the bearing portion arrangement portion 13g, the length L1 from the position where the holding portion 55d contacts the output shaft 22b to the curved portion between the holding portion 55d and the inclined portion 55c is formed to be longer than the length L2 from the front end of the tapered portion 55e to the upper surface of the third limiting portion 30. Thus, for example, even if the position of the urging member 55 is displaced downward in the bearing portion arrangement portion 13g, the third limiting portion 30 abuts against the front end of the tapered portion 55e to limit the displacement, and even in a state where the urging member 55 is displaced, the output shaft 22b can be retained by the holding portion 55d.

[0091] The tapered portion 55e is continuous with the front end of the holding portion 55d. The pair of tapered portions 55e are bent outwardly in the Y direction relative to the holding portion 55d in a manner that gradually separates as they move away from the continuous portion 55a. By pushing the output shaft 22b toward the force applying portions 56A and 56B from the outside of the tapered portion 55e, the interval between the pair of holding portions 55d is expanded as the tapered portion 55e is tilted.

[0092] (Function of the bearing)

[0093] By disposing the cover 26 after disposing the motor 22 including the worm 24 and the transmission mechanism 40 in the housing body 13 with the urging member 55 disposed in the bearing portion disposing portion 13g, the limiting portions 28 and 30 are disposed in the bearing portion disposing portion 13g. As a result, the urging member 55 is fixed to the housing body 13 in an irremovable manner, and the output shaft 22b is held between the pair of urging portions 56A and 56B. The urging portions 56A and 56B are respectively bent in the direction of moving away from the output shaft 22b in the approaching / separating direction B, and due to this bending, the output shaft 22b is elastically urged in the direction B1 moving away from the worm wheel 35 and in the direction B2 moving toward the worm wheel 35.

[0094] Here, there is an inevitable error in the assembly position of the urging member 55 to the bearing portion configuration portion 13g and the assembly position of the motor 22 to the motor body configuration portion 13d. Therefore, even if the output shaft 22b of the motor 22 is designed to pass through the center of the bearing portion configuration portion 13g in the Y direction, it will not be located in the center between the pair of urging parts 56A and 56B of the urging member 55. That is, the assembly position of the urging member 55 on the output shaft 22b will deviate in the direction B1 away from the worm wheel 35 or in the direction B2 approaching the worm wheel 35. As a result, although the forces of the urging parts 56A and 56B are the same, the forces in the direction deviating from the position become stronger, so that the output shaft 22b interferes with the bearing 22c according to the direction, and the interference state is maintained by the urging parts 56A and 56B. In addition, a predetermined gap is ensured between the tooth portion 24b of the worm 24 and the helical teeth 35a of the worm wheel 35 within the range that can ensure meshing.

[0095] When the motor 22 is driven, due to the meshing of the tooth portion 24b of the worm 24 and the helical teeth 35a of the worm wheel 35, a force to move in the approaching / separating direction B acts on the output shaft 22b, and the force applying portions 56A and 56B are used to allow and suppress the movement within a predetermined range. That is, the first force applying portion 56A is used to suppress the movement of the output shaft 22b in the direction B2 approaching the worm wheel 35, and the second force applying portion 56B is used to suppress the movement of the output shaft 22b in the direction B1 away from the worm wheel 35. Therefore, the vibratory rotation of the output shaft 22b in the approaching / separating direction B can be effectively suppressed on the basis of ensuring the meshing of the worm 24 and the worm wheel 35. In addition, the force applying portion 56A or 56B can be used to keep the output shaft 22b at a position that interferes with the bearing 22c. As a result, even if the bearing 22c is de-oiled, the generation of abnormal noise caused by the collision between the output shaft 22b and the bearing 22c can be effectively suppressed.

[0096] In the second embodiment, the worm 24 can be held at a position specified via the output shaft 22b relative to the worm wheel 35 by a pair of biasing portions 56A and 56B. Therefore, since the friction resistance between the worm 24 and the worm wheel 35 can be reduced, the worm 24 can be smoothly rotated. As a result, the load applied to the motor 22 can be effectively reduced.

[0097] By attaching the cover 26 to the housing body 13, the first restricting portion 28 and the third restricting portion 30 can prevent the urging member 55 from falling off the bearing placement portion 13g. Therefore, it is possible to prevent an unintended malfunction caused by using a single urging member 55.

[0098] (Third embodiment)

[0099] Fig.14 and Fig.15The electric steering lock device 10 having the electric actuator 20 of the third embodiment is shown. In the third embodiment, the bearing portion 27 is different from the first embodiment in that it includes a pair of biasing members (biasing portions) 60A and 60B formed separately from the cover 26, and the output shaft 22b of the motor 22 is biased in the approaching / separating direction B by the biasing members 60A and 60B.

[0100] In the housing body 13, a bearing configuration portion 13g similar to that of the first embodiment is formed on the front end side of the worm 24 of the output shaft 22b. The bearing configuration portion 13g includes a first force member configuration portion (configuration portion) 13o on the front end side of the output shaft 22b and on the worm wheel 35 side. In addition, the housing body 13 of the third embodiment includes a second force member configuration portion (configuration portion) 13p on the base end side of the worm 24 of the output shaft 22b, that is, on the motor body 22a side. The second force member configuration portion 13p is adjacent to the opposite side of the worm wheel 35 relative to the output shaft 22b. Refer to Fig.16 The first urging member placement portion 13o is formed of a groove that is recessed upward in the Z direction. Similar to the first urging member placement portion 13o, the second urging member placement portion 13p is also formed of a groove that is recessed upward in the Z direction.

[0101] Reference Fig.14 The cover 26 includes the first to third limiting parts 28 to 30 for limiting the movement of the front end of the output shaft 22b, similarly to the first embodiment. The first to third limiting parts 28 to 30 cooperate with the first force applying member 60A to form a bearing part 27. In addition, the first limiting part 28 and the third limiting part 30 also function as a separate component for preventing the first force applying member 60A from falling off. In addition, the support part 26a included in the cover 26 also functions as a separate component for preventing the second force applying member 60B from falling off.

[0102] like Figure 14 to Figure 16 As shown, the first force member (first force portion) 60A is arranged at the first force member arrangement portion 13o, and the first force member arrangement portion 13o is located on the front end side of the worm 24 of the output shaft 22b. The second force member (second force portion) 60B is arranged at the second force member arrangement portion 13p, and the second force member arrangement portion 13p is located on the base end side of the worm 24 of the output shaft 22b. Each of the force members 60A and 60B is composed of a metal leaf spring. The first force member 60A applies force to the output shaft 22b in the direction B1 away from the worm wheel 35, and the second force member 60B applies force to the output shaft 22b in the direction B2 approaching the worm wheel 35. They have the same shape, and one of them arranged at the first force member arrangement portion 13o constitutes the first force member 60A, and the other one arranged at the second force member arrangement portion 13p constitutes the second force member 60B.

[0103] like Fig.16 and Fig.17 As shown in FIG. 1 , the force applying members 60A and 60B include a contact portion (first portion) 60a, a continuous portion (second portion) 60b, and a side portion (third portion) 60c. Since the contact portion 60a is bent with the bent portion between the contact portion 60a and the continuous portion 60b as a fulcrum, an elastic force is generated on the contact portion 60a. The force is adjusted by the material and thickness of the force applying members 60A and 60B. In addition, the assembly state of the second force applying member 60B is the same as that of the second force applying member 60B. Fig.16 The assembled state of the first urging member 60A shown is the same.

[0104] The contact portion 60a is arranged roughly along the XZ plane and is in line contact with the output shaft 22b. Since the output shaft 22b is arranged between the contact portion 60a and the second limiting portion 29, the contact portion 60a is bent in a direction away from the output shaft 22b. That is, when the output shaft 22b is not held, the interval between the contact portion 60a and the second limiting portion 29 is smaller than the diameter of the output shaft 22b. A tapered portion 60d is formed at the lower end of the contact portion 60a, and the tapered portion 60d is bent in a direction away from the output shaft 22b.

[0105] The continuous portion 60b is continuous with the upper end of the contact portion 60a and is bent in a direction away from the output shaft 22b relative to the contact portion 60a. The continuous portion 60b is arranged along the bottom surface 13q of the biasing member arrangement portions 13o and 13p.

[0106] The side portion 60c is continuous with the front end of the continuous portion 60b and is bent relative to the continuous portion 60b in the same direction as the contact portion 60a. The side portion 60c is arranged along the side surface 13r of the force member arrangement portion 13o, 13p. The side portion 60c is provided with a locking portion 60e, which protrudes in the direction opposite to the contact portion 60a and is locked to the side surface (inner wall) 13r of the force member arrangement portion 13o, 13p. The locking portion 60e is a lifting structure in which the inside of the roughly "U"-shaped slit formed in the side portion 60c is bent outward. The locking portion 60e is inclined in such a way that the lower end is located at the farthest position from the side portion 60c.

[0107] (Function of the bearing)

[0108] In a state where the urging members 60A and 60B are respectively arranged in the urging member arrangement portions 13o and 13p, the motor 22 including the worm 24 and the transmission mechanism 40 are arranged in the housing body 13, and then the cover 26 is arranged to arrange the restricting portions 28 to 30 in the bearing arrangement portion 13g. The urging members 60A and 60B are respectively bent in the direction of moving away from the output shaft 22b in the approach / separation direction B, and due to this bending, the output shaft 22b is elastically urged in the direction B1 moving away from the worm wheel 35 and in the direction B2 approaching. Although the urging members 60A and 60B have the same acting force, the urging member 60A side that urges the front end side of the output shaft 22b is larger in the moment of the force acting on the output shaft 22b. As a result, the output shaft 22b is held in a state that interferes with the fixed position of the bearing 22c. Furthermore, a predetermined gap is ensured between the tooth portion 24 b of the worm 24 and the helical teeth 35 a of the worm wheel 35 within a range that allows meshing to be ensured.

[0109] When the motor 22 is driven, due to the meshing of the tooth portion 24b of the worm 24 and the helical teeth 35a of the worm wheel 35, a force to move in the approach / separation direction B acts on the output shaft 22b, and the force applying members 60A and 60B are used to allow and suppress the movement within a predetermined range. That is, the first force applying member 60A is used to suppress the movement of the output shaft 22b in the direction B2 approaching the worm wheel 35, and the second force applying member 60B is used to suppress the movement of the output shaft 22b in the direction B1 away from the worm wheel 35. Therefore, it is possible to effectively suppress the vibratory rotation of the output shaft 22b in the approach / separation direction B on the basis of ensuring the meshing of the worm 24 and the worm wheel 35. In addition, the force applying members 60A and 60B can be used to keep the output shaft 22b in a state that interferes with the fixed position of the bearing 22c. As a result, the collision sound caused by the repeated interference and separation of the output shaft 22b and the bearing 22c can be reduced. Thus, even if oil loss occurs in the bearing 22c, the generation of abnormal noise due to the collision between the output shaft 22b and the bearing 22c can be effectively suppressed.

[0110] In the third embodiment, since the first force applying member 60A is arranged on the front end side and the second force applying member 60B is arranged on the base end side with respect to the output shaft 22b, the moment of the force acting on the output shaft 22b is stronger on the front end side. Therefore, since the output shaft 22b can be kept in a state of being forced toward B1 away from the worm wheel 35, and the friction resistance between the worm 24 and the worm wheel 35 can be reduced, the worm 24 can be smoothly rotated. As a result, the load applied to the motor 22 can be effectively reduced.

[0111] Furthermore, since the urging members 60A and 60B of the third embodiment have the locking portion 60e protruding from the side portion 60c, the urging members 60A and 60B can be effectively prevented from falling off from the urging member placement portions 13o and 13p. Therefore, unintended failures caused by providing independent urging members 60A and 60B can be prevented from occurring.

[0112] In addition, the electric actuator 20 of the present invention is not limited to the configuration of the above-mentioned embodiment, and various modifications can be made.

[0113] For example, the urging portions 56A and 56B shown in the second embodiment and the urging members 60A and 60B (contact portion 60a) shown in the third embodiment may be integrally provided on the cover 26 like the urging portion 31 of the first embodiment. In addition, the first to third limiting portions 28 to 30 shown in the first to third embodiments may not be provided, and only one of them may be provided as required.

[0114] Although the present invention has been described by taking the electric steering lock device 10 of a vehicle as an example, the electric actuator 20 of the present invention can also be applied to devices other than the electric steering lock device 10 .

[0115] [Explanation of Reference Numerals]

[0116] 1 steering shaft, 2 shaft ring, 2a tooth portion, 10 steering lock device, 12 housing, 13 housing body, 13a hole, 13b top wall, 13c partition wall, 13d motor body configuration portion, 13e output shaft configuration portion, 13f worm configuration portion, 13g bearing configuration portion, 13h cylindrical wall, 13i transmission mechanism configuration portion, 13j insertion hole, 13k guide groove, 13m bottom surface, 13n side surface, 13o first force application member configuration portion, 13p second force application member component arrangement portion, 13q bottom surface, 13r side surface, 14 housing cover, 14a hole, 14b rotation holding portion, 14c positioning protrusion, 14d through hole, 15 connecting pin, 16 locking bolt, 16a connecting hole, 20 electric actuator, 22 motor, 22a motor body, 22b output shaft, 22c bearing, 22d through hole, 24 worm, 24a body, 24b tooth portion, 26 cover, 26a support portion, 26b through hole, 27 bearing portion, 28 1st limiting portion, 29 2nd limiting portion, 29a supporting surface, 30 3rd limiting portion, 31 force-applying portion, 31a contact surface, 35 worm gear, 35a helical tooth, 35b gear portion, 35c cylindrical portion, 35d thread groove, 40 transmission mechanism, 42 slider, 42a insertion portion, 42b threaded protrusion, 42c holding portion, 42d anti-rotation portion, 44 spring, 45 connecting pin, 46 spring, 50 control substrate, 51 connector, 55 force-applying member, 55a continuous portion , 55b side portion, 55c inclined portion, 55d retaining portion, 55e tapered portion, 56A first force applying portion, 56B second force applying portion, 60A first force applying member (first force applying portion), 60B second force applying member (second force applying portion), 60a abutting portion, 60b continuous portion, 60c side portion, 60d tapered portion, 60e locking portion, A axis line of the worm wheel, B approach / departure direction, B1 departure direction (first direction), B2 approach direction (second direction).

Claims

1. An electric actuator, comprising: A motor having a rotatable output shaft including a front end and a base end opposite to the front end, and a bearing rotatably holding the output shaft. A worm gear is mounted on the output shaft. a worm wheel, which meshes with the worm, The force applying portion applies force to the output shaft in a direction in which the worm approaches and moves away from the worm wheel, that is, in a direction in which the worm approaches and moves away from the worm wheel, as viewed from a direction in which the axis of the worm wheel extends. a resin cover covering the worm, and a housing that accommodates the motor, the worm, the worm wheel, and the cover; The force applying portion is integrally constructed with the cover, is arranged on the front end side of the worm of the output shaft, and applies force to the output shaft in a first direction away from the worm wheel in the approaching and separating directions; The cover is provided with a support portion that supports the output shaft at a proximal end side of the worm.

2. The electric actuator according to claim 1, wherein: The cover includes a restriction portion adjacent to the opposite side of the worm wheel relative to the output shaft; The force applying portion is arranged at a position opposite to the restricting portion across the output shaft; The restriction portion and the urging portion protrude from the cover toward the output shaft.

3. An electric actuator, comprising: A motor having a rotatable output shaft and a bearing for rotatably holding the output shaft. A worm gear is mounted on the output shaft. a worm wheel, which meshes with the worm, The force applying portion applies force to the output shaft in a direction in which the worm approaches and moves away from the worm wheel, that is, in a direction in which the worm approaches and moves away from the worm wheel, as viewed from a direction in which the axis of the worm wheel extends. a housing that accommodates the motor, the worm and the worm wheel, and a resin cover covering the worm; The housing has a configuration portion, the configuration portion is located on the front end side of the output shaft and is recessed in a direction intersecting with the approaching and separating directions; The force applying portion is composed of a leaf spring arranged in the arrangement portion; The leaf spring comprises: a first biasing portion for biasing the output shaft in a first direction away from the worm wheel in the approaching and separating directions; and The second urging portion urges the output shaft in a second direction approaching the worm wheel in the approaching and separating directions.

4. The electric actuator according to claim 3, wherein: The cover is provided with a restriction portion that restricts movement of the leaf spring.

5. An electric actuator comprising: A motor having an output shaft and a bearing, wherein the output shaft includes a front end and a base end opposite to the front end, and the bearing rotatably holds the output shaft. A worm gear is mounted on the output shaft. a worm wheel, which meshes with the worm, a force applying portion, which applies force to the output shaft in a direction in which the worm approaches and moves away from the worm wheel, that is, in a direction in which the worm approaches and moves away from the worm wheel, as viewed from a direction in which the axis of the worm wheel extends; and a housing that accommodates the motor, the worm and the worm wheel; The housing has a first arrangement portion and a second arrangement portion, the first arrangement portion is located on the front end side of the worm of the output shaft and is recessed in a direction intersecting the approaching and separating directions, and the second arrangement portion is located on the base end side of the worm of the output shaft and is recessed in a direction intersecting the approaching and separating directions; The force applying part includes: a first biasing portion disposed at the first disposition portion and biasing the output shaft in a first direction away from the worm wheel in the approaching and separating directions; and a second force applying portion, which is disposed at the second arrangement portion and applies force to the output shaft in a second direction approaching the worm wheel in the approaching and separating directions; The first urging portion and the second urging portion are both formed of leaf springs.

6. An electric actuator comprising: A motor having a rotatable output shaft and a bearing for rotatably holding the output shaft. A worm gear is mounted on the output shaft. a worm wheel, which meshes with the worm, a force applying portion, which applies force to the output shaft in a direction in which the worm approaches and moves away from the worm wheel, that is, in a direction in which the worm approaches and moves away from the worm wheel, as viewed from a direction in which the axis of the worm wheel extends; and a housing having a configuration portion adjacent to the output shaft, the housing accommodating the motor, the worm and the worm wheel; The force applying portion is composed of a leaf spring arranged in the arrangement portion; The leaf spring comprises: The first part is in contact with the output shaft. a second portion that is bent relative to the first portion in a direction away from the output shaft, and a third portion, which is bent relative to the second portion in the same direction as the first portion; The third portion is provided with a locking portion that protrudes in a direction opposite to the first portion and is locked to an inner wall of the placement portion.

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