JP2020139540A - Electric actuator - Google Patents

Abstract

To prevent damage of a shaft case without causing an increase of costs in an electric actuator in which a screw shaft is housed in the shaft case having a bottomed cylindrical shape.SOLUTION: A rotation restriction part 70 which restricts rotation of a screw shaft 31 around an axis has: an axial guide groove 35c formed on an inner peripheral surface of a shaft case 35; and a guide collar 72 serving as a rotating body which is fitted in the guide groove 35c while rotatably supported by a support shaft pin 72 attached to the screw shaft 31. The guide collar 72 is formed by an elastic material such as a rubber material. A bottom part 35b of the shaft case 35 is provided with a contact surface 35b2 which is not brought into contact with the screw shaft 31 in an axial direction and may be brought into contact with the guide collar 72 in the axial direction.SELECTED DRAWING: Figure 4

Description

The present invention relates to an electric actuator.

In recent years, in vehicles such as automobiles, electrification has progressed in order to save labor and reduce fuel consumption. For example, a system has been developed in which an automatic transmission, a brake, a steering wheel, and the like are operated by the power of an electric motor. It has been put on the market. As an actuator used for such an application, for example, in Patent Document 1 below, a ball screw (ball screw mechanism) is adopted as a motion conversion mechanism that converts the rotary motion of an electric motor into a linear motion and outputs it. Is disclosed.

The electric actuator of Patent Document 1 is provided with a rotation restricting unit for restricting the rotation of the screw shaft of the ball screw around the axis when the nut of the ball screw is rotated by receiving the rotational movement of the electric motor. Has been done. The rotation control unit includes a pin attached to the screw shaft so that both ends protrude outward in the radial direction of the screw shaft, and a cylindrical rotating body (guide collar) rotatably attached to one end and the other end of the pin. It is formed on the inner peripheral surface of the casing of the electric actuator (a bottomed cylindrical shaft case accommodating the rear end portion of the screw shaft), and includes an axial guide groove accommodating the guide collar.

Japanese Unexamined Patent Publication No. 2017-184484

When a bottomed tubular shaft case for accommodating a screw shaft is provided as in Patent Document 1, the rear end of the screw shaft is placed on the bottom of the shaft case due to a handling error during assembly work or a malfunction of an electric actuator. If it collides, the shaft case may be deformed or damaged, and the electric actuator may malfunction. However, in the electric actuator of Patent Document 1, no measures are taken to prevent damage to the shaft case. For example, if another member (buffer member) having a cushioning function is attached and fixed to the rear end of the screw shaft so that the cushioning member collides with the bottom of the shaft case, damage to the shaft case can be prevented as much as possible. However, the additional cushioning member increases the parts cost, processing cost, assembly cost, and the like, resulting in a significant cost increase.

Therefore, an object of the present invention is to damage an electric actuator in which (a part of) a screw shaft constituting a motion conversion mechanism is housed in a bottomed tubular shaft case without causing an increase in cost. It is to make it possible to prevent it as much as possible.

The present invention, which was devised to achieve the above object, includes a drive unit having an electric motor and a motion conversion mechanism unit that converts the rotational motion of the drive unit into a linear motion, and the motion conversion mechanism unit is the drive unit. It has a nut that rotates in response to the rotational movement of the above, and a screw shaft that moves forward and backward in the axial direction while the rotation around the axis is restricted as the nut rotates, and the screw shaft has a bottomed tubular shape. In the electric actuator housed in the shaft case, a rotation regulating portion for restricting the rotation of the screw shaft is provided on the screw shaft, which is formed of an axial guide groove formed on the inner peripheral surface of the shaft case and an elastic material. It has a rotating body fitted in the guide groove in a state where it can rotate around the provided radial support shaft, and does not abut on the bottom of the shaft case in the axial direction with the rotating body. It is characterized in that a contact surface that can be contacted in the axial direction is provided.

According to the above configuration, when the screw shaft moves linearly (backward movement) in a direction approaching the bottom of the shaft case, the rotating body provided on the screw shaft moves to the bottom and shaft of the shaft case before the screw shaft. It is possible to contact in the direction. Since the rotating body is made of an elastic material such as a rubber material, even if the rotating body collides with the bottom (contact surface) of the shaft case, the impact load is absorbed and relaxed. Therefore, deformation and breakage of the shaft case can be prevented as much as possible. Further, since the rotating body functioning as the cushioning member is one component of the existing rotation regulating portion, it is possible to avoid a special cost increase that may occur when a separate cushioning member is provided on the screw shaft.

From the viewpoint of appropriately guiding the advancing / retreating movement of the screw shaft while appropriately exerting the cushioning function, it is preferable to provide the rotating bodies at a plurality of locations separated in the circumferential direction of the screw shaft.

The above-mentioned support shaft can be composed of a support pin attached to the screw shaft (a member different from the screw shaft), and the rotating body is composed of a cylindrical member rotatably supported by the support pin. be able to.

The configuration of the present invention described above can be preferably applied to, for example, an electric actuator in which a screw shaft is arranged in parallel with a rotation shaft of an electric motor.

From the above, according to the present invention, in the electric actuator in which the screw shaft is housed in the bottomed tubular shaft case, damage to the shaft case can be prevented as much as possible without causing a particular cost increase. It becomes possible.

It is the schematic sectional drawing of the electric actuator which concerns on one Embodiment of this invention. It is a schematic perspective view of the electric actuator shown in FIG. FIG. 1 is a cross-sectional view taken along the line AA of FIG. FIG. 1 is a cross-sectional view taken along the line BB of FIG. It is a partially enlarged sectional view of the electric actuator which concerns on other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The "one side in the axial direction" used in the following description is the left side of the paper surface in FIG. 1, and the "other side in the axial direction" is the right side of the paper surface in FIG.

FIG. 1 is a schematic vertical sectional view of an electric actuator 1 according to an embodiment of the present invention, FIG. 2 is a schematic perspective view of the electric actuator 1, and FIG. 3 is a view taken along the line AA of FIG. It is a cross-sectional view, and FIG. 4 is a cross-sectional view taken along the line BB of FIG. The electric actuator 1 has a drive unit 2 that generates a rotational drive force and a motion conversion mechanism that converts a rotational drive force (rotational motion) that is output from the drive unit 2 and transmitted via the drive force transmission unit 4 into a linear motion. A lock that stops driving the motion conversion mechanism unit 3, the support unit 5 that supports the motion conversion mechanism unit 3, the operation unit 6 that outputs (transmits) the linear motion of the motion conversion mechanism unit 3 to the operation target, and the motion conversion mechanism unit 3. A mechanism unit 7 is provided. The drive unit 2 includes a motor unit 8 and a speed reduction mechanism unit 9.

The motor unit 8 mainly includes an electric motor 10 for driving an actuator and a motor case 11 containing the electric motor 10. The motor case 11 includes a case main body 12 and a sealing member 13 that seals an end opening on one side of the case main body 12 in the axial direction.

One end of a bus bar 14 (see FIG. 2) as a conductive member is connected to a motor terminal (not shown) of the electric motor 10, and the other end of the bus bar 14 is pulled out to the outside of the motor case 11 and is not shown. It is connected to a power source (not shown) via an external power line. As the electric motor 10, a DC motor with a brush, a brushless motor, or the like is used.

The speed reduction mechanism unit 9 includes a speed reducer 15 that decelerates and outputs the rotation of the motor unit 8 (electric motor 10), and a speed reducer case 16 that houses the speed reducer 15. The speed reducer case 16 is separably connected to the case body 12 of the motor case 11 arranged adjacent to one side in the axial direction thereof.

A planetary gear reducer is used for the speed reducer 15. That is, the speed reducer 15 is arranged between the sun gear 17 provided so as to be integrally rotatable with the output shaft 10a of the electric motor 10, the ring gear 18 provided on the inner circumference of the speed reducer case 16, and the sun gear 17 and the ring gear 18. A plurality of (for example, three) planetary gears 19 that mesh with the sun gear 17 and the ring gear 18 and a planetary gear holder 20 and a planetary gear carrier 21 that rotatably hold the planetary gears 19 are provided. The planetary gear carrier 21 integrally has an annular portion 21a connected to the planetary gear 19 and a cylindrical portion 21b extending axially from the inner diameter end of the annular portion 20a to the other side in the axial direction, and causes the planetary gear 19 to revolve. Take out and output. The cylindrical portion 21b of the planetary gear carrier 21 is integrally rotatably connected to the rolling bearing 46 (inner ring) and the gear boss 44, which will be described later.

The speed reducer 15 having the above configuration decelerates the rotational movement of the output shaft 10a of the electric motor 10 and then transmits the rotational movement to the driving force transmission unit 4 and further to the motion conversion mechanism unit 3. As a result, the rotational torque of the driving force transmission unit 4 can be increased, so that a small electric motor 10 can be adopted.

The motion conversion mechanism unit 3 of the present embodiment is composed of a ball screw 30. The ball screw 30 includes a screw shaft 31 arranged in parallel with the output shaft 10a of the electric motor 10, a nut 32 rotatably fitted to the outer periphery of the screw shaft 31 via a large number of balls 33, and a circulation member. It is equipped with a screw 34. A large number of balls 33 are loaded between the spiral groove 31a formed on the outer peripheral surface of the screw shaft 31 and the spiral groove 32a formed on the inner peripheral surface of the nut 32, and the frame 34 is incorporated. With such a configuration, when the screw shaft 31 moves forward and backward in the axial direction (forward movement in one axial direction or backward movement in the other axial direction) as the nut 32 rotates around its central axis. The ball 33 circulates between the spiral grooves 31a and 32a.

The screw shaft 31 constitutes an output member of the electric actuator 1, and an operation unit 6 for operating an operation target (not shown) is provided at one end on one side in the axial direction thereof. In the illustrated example, the operation unit 6 is composed of a radial through hole into which a connecting member for connecting the operation target and the screw shaft 31 is inserted.

The electric actuator 1 is provided with a bottomed tubular shaft case 35 having a tubular portion 35a and a bottom portion 35b, and (a part of) a screw shaft 31 is housed in the shaft case 35. The shaft case 35 has a tubular holder portion 66 (details will be described later) that houses the lock mechanism portion 7, and is separably connected to the transmission gear case 45 that constitutes the driving force transmission portion 4. Further, the electric actuator 1 is provided with a rotation regulating portion 70 for restricting the rotation of the screw shaft 31 around the central axis when the nut 32 is rotated. The rotation regulation unit 70 will be described in detail later.

The electric actuator 1 is provided with a position detecting device for detecting the amount of forward / backward movement (axial position) of the screw shaft 31. This position detection device is mainly composed of a magnetic sensor 36 (see FIG. 2) as a stroke sensor attached to the motor case 11 and a permanent magnet 37 as a sensor target attached to the screw shaft 31. The permanent magnet 37 is attached to the screw shaft 31 via the holding member 38. In this case, when the screw shaft 31 moves back and forth in the axial direction, the magnetic sensor 36 detects a change in the magnetic field (for example, the direction and strength of the magnetic flux density) of the permanent magnet 37 that moves along with the screw shaft 31. The amount of forward / backward movement of 31 is detected.

The driving force transmission unit 4 mainly includes a transmission gear mechanism 41 that transmits the output of the drive unit 2 (reduction mechanism unit 9) to the motion conversion mechanism unit 3, and a transmission gear case 45 that houses the transmission gear mechanism 41. The transmission gear case 45 is separably connected to the speed reducer case 16 arranged adjacent to one side in the axial direction thereof.

The transmission gear mechanism 41 includes a ring-shaped drive gear 42 on the drive side, a driven gear 43 on the driven side that meshes with the drive gear 42, and a gear boss 44 arranged on the inner circumference of the drive gear 42. The gear boss 44 is a shaft. It is rotatably supported by rolling bearings 46 and 47 arranged at two points in the direction apart from each other. The rolling bearings 46 and 47 are mounted on the inner circumferences of the bearing cases 51 constituting the transmission gear case 45 and the support portion 5, respectively.

The gear boss 44 is formed in a stepped cylindrical shape having a small-diameter cylindrical portion 44a and a large-diameter cylindrical portion 44b integrally, and is arranged coaxially with the rotating shaft 10a of the electric motor 10. The inner peripheral surface of the cylindrical portion 21a of the planetary gear carrier 21 is press-fitted into the outer peripheral surface of the small-diameter cylindrical portion 44a, and the inner peripheral surface of the drive gear 42 is press-fitted into the outer peripheral surface of the large-diameter cylindrical portion 44b. In the present embodiment, a part of the rotating shaft 10a of the electric motor 10 on the free end side is arranged on the inner circumference of the gear boss 44 via a radial gap.

The driven gear 43 has a cylindrical nut mounting portion 43a arranged on the radial outer side of the nut 32 of the ball screw 30, and in the present embodiment, the outer peripheral surface of the nut 32 is press-fitted into the inner peripheral surface of the nut mounting portion 43a. ing.

With the above configuration, when the rotating shaft 10a of the electric motor 10 rotates and the rotational driving force is transmitted to the gear boss 44 via the speed reducer 15, the gear boss 44 and the drive gear 42 rotate integrally and with the gear boss 44. The meshed driven gear 43 and the nut 32 of the ball screw 30 rotate integrally. As a result, the screw shaft 31 of the ball screw 30 moves back and forth in the axial direction according to the rotation direction of the nut 32, and the operation target connected to the operation portion 6 of the screw shaft 31 is operated.

The transmission gear case 45 has a cylindrical portion 45a that accommodates a part of the screw shaft 31. A tubular boot 47 is attached between the cylindrical portion 45a and the screw shaft 31. The boot 47 is formed of an elastic material such as a resin material, a rubber material, or a thermoplastic elastomer, and integrally has a small-diameter tubular portion 47a and a large-diameter tubular portion 47b, and a bellows portion 47c connecting both tubular portions 47a and 47b. .. The small-diameter tubular portion 47a is tightened and fixed to the screw shaft 31 by the boot band 48A, and the large-diameter tubular portion 47b is tightened and fixed to the cylindrical portion 45a of the transmission gear case 45 by the boot band 48B. With such a configuration, foreign matter is prevented from entering the transmission gear case 45. A boot cover 49 for protecting the boot 47 is arranged on the outer periphery of the boot 47. The boot cover 49 of the present embodiment is provided integrally with the case body 12 constituting the motor case 11.

The support portion 5 includes a support bearing 50 that rotatably supports the nut 32 of the ball screw 30, and a bearing case 51 that houses the support bearing 50. The bearing case 51 is separably connected to a transmission gear case 45 arranged adjacent to one side in the axial direction thereof.

The support bearing 50 includes an outer ring 50a and an inner ring 50b, and a double-row ball 50c rotatably arranged between them, and is capable of supporting a radial load and an axial load in both directions. Bearings are used. Between the bearing case 51 and the support bearing 50, a flanged cylindrical sleeve 52 having a flange portion 52a facing inward in the radial direction is arranged, and the outer ring 50a of the support bearing 50 is the collar of the sleeve 52. Positioning in the axial direction is performed by being sandwiched between the portion 52a and the retaining ring 53 mounted on the inner peripheral surface of the sleeve 52. On the other hand, the inner ring 50b of the support bearing 50 is positioned in the axial direction by being sandwiched between the driven gear 43 and the retaining ring 54 mounted on the outer peripheral surface of the nut 32.

The lock mechanism portion 7 is a lock mechanism drive housed in a lock member 60, a slide screw nut 61, a slide screw shaft 62, a lock member fixing plate 63, and a tubular holder portion 66 provided in the shaft case 35. A motor 64, a spring (compression coil spring) 65, and a lock sensor (not shown) for grasping whether the lock mechanism portion 7 is in the locked state or the unlocked state are provided.

The lock member 60 has a non-round portion 60a having a non-round cross section inserted into a non-round (for example, rectangular) through hole 51a provided in the bearing case 51, and the lock member fixing plate 63. It is bolted to the sliding screw nut 61 via. The sliding screw nut 61 is screwed to the outer circumference of the sliding screw shaft 62. The sliding screw shaft 62 is rotatably connected to the output shaft of the lock mechanism driving motor 64. The spring 65 is mounted on the outer circumference of the sliding screw shaft 62, and is interposed between the radial protrusion 66a provided on the holder portion 66 and the sliding screw nut 61 (lock member fixing plate 63) in a compressed state. The opening at the other end of the holder portion 66 in the axial direction is sealed with a bottomed tubular cap 67. Although not shown, the lock mechanism drive motor 64 is connected to a power power source (a power power source that supplies electric power to the electric motor 10) via a power line.

The drive gear 42 is arranged in the direction in which the lock member 60 advances, and holes 42a into which the non-round portion 60a of the lock member 60 is inserted are formed at a plurality of locations separated in the circumferential direction of the drive gear 42. ing. When the lock mechanism portion 7 is in the locked state (FIG. 1), the non-round portion 60a of the lock member 60 is inserted into any of the plurality of hole portions 42a, and is inserted into the drive gear 42 in the circumferential direction (drive). Engage in the direction of rotation of the gear 42).

The lock mechanism unit 7 having the above configuration operates as follows. First, in a state where power is not supplied to the lock mechanism drive motor 64, the lock member 60 is urged to one side in the axial direction by the spring 65, and the non-round portion 60a of the lock member 60 is the hole portion of the drive gear 42. Since it is inserted into the 42a, the drive gear 42 is in a locked state in which the rotation (advance / retreat movement of the screw shaft 31) is restricted.

When electric power is supplied to the electric motor 10 from this state, electric power is also supplied to the lock mechanism drive motor 64, and the output shaft of the lock mechanism drive motor 64 and the sliding screw shaft 62 connected to the output shaft are locked. It is rotationally driven in the direction of moving the member 60 backward. At this time, the sliding screw nut 61 is prevented from rotating by inserting the non-round portion 60a of the lock member 60 fixed to the non-round portion 60a into the non-round through hole 51a provided in the bearing case 51. Therefore, when the sliding screw shaft 62 rotates, the sliding screw nut 61 and the lock member 60 move backward against the urging force of the spring 65. As a result, the non-round portion 60a of the lock member 60 is separated from the hole portion 42a of the drive gear 42, and the lock member 60 is in an unlocked state in which rotation is allowed. While the electric motor 10 is supplied with electric power, it is held in the above unlocked state.

After that, when the power supply to the electric motor 10 is cut off and the drive of the screw shaft 31 is stopped, the power supply to the lock mechanism drive motor 64 is also cut off. As a result, the driving force for moving the lock member 60 and the sliding screw nut 61 backward is not generated, so that the locking member 60 and the sliding screw nut 61 are urged to one side in the axial direction by the elastic restoring force of the spring 65 and locked. The non-round portion 60a of the member 60 is inserted into the hole portion 42a of the drive gear 42. As a result, the rotation of the drive gear 42 is restricted to a locked state.

By restricting the rotation of the drive gear 42 in this way, the output of the drive unit 2 is not transmitted to the motion conversion mechanism unit 3, and the screw shaft 31 is held in a state where it does not move forward or backward. As a result, even when an external force is input to the screw shaft 31 from the operation target, the screw shaft 31 can be held at a predetermined position in the axial direction.

In the present embodiment, the lock member 60 is moved backward by driving the lock mechanism drive motor 64, but on the contrary, in order to move the lock member 60 forward, the lock member 60 is used for driving the lock mechanism. The motor 64 may be driven.

Hereinafter, the characteristic configuration adopted in the electric actuator 1 of the present embodiment will be described in detail.

As shown in FIGS. 1, 3 and 4, the other end (rear end) of the screw shaft 31 in the axial direction restricts the screw shaft 31 from rotating around its axis when the nut 32 rotates. A rotation control unit 70 is provided for this purpose. The rotation restricting portion 70 includes an axial guide groove 35c formed on the inner peripheral surface of the tubular portion 35a of the shaft case 35 and a guide groove in a state of being rotatable around a radial support shaft provided on the screw shaft 31. It has a guide collar 72 as a rotating body fitted in the 35c. The guide collar 72 is made of an elastic material such as a resin material, a rubber material, or a thermoplastic elastomer.

The support shaft is composed of a support pin 71 mounted (press-fitted) in a radial mounting hole (through hole) 31b provided in the screw shaft 31 so that both ends project outward in the radial direction of the screw shaft 31. The guide collar 72 is rotatably supported by being squeezed into each of one end and the other end of the support pin 71. Therefore, the guide collars 72 (and the guide grooves 35c into which the guide collars 72 are fitted) are arranged at two locations separated in the circumferential direction (the phases in the circumferential direction are different by 180 °). In the present embodiment, a part of the guide collar 72 projects to the other side in the axial direction from the end surface 31c on the other side in the axial direction of the screw shaft 31.

The rotation control unit 70 of the present embodiment prepares an assembly in which the support pin 71 and the guide collar 72 are attached to the screw shaft 31, and then phase-aligns the guide collar 72 with the guide groove 35c provided in the shaft case 35. Is completed by incorporating the above assembly into the shaft case 35 in this state. At this time, since the support pin 71 is press-fitted into the mounting hole 31b of the screw shaft 31, the assembly does not fall off from the screw shaft 31 regardless of the posture of the assembly during the assembly work. Therefore, the workability of the built-in work is improved.

As described above, the electric actuator 1 of the present embodiment is provided with a position detecting device for detecting the advancing / retreating movement amount (axial position) of the screw shaft 31, and the screw shaft 31 is located on the outer periphery thereof. Since the provided guide roller 72 moves (rolls) along the guide groove 35c provided in the shaft case 35 to move forward and backward, the forward and backward limits of the screw shaft 31 can be controlled. Therefore, the screw shaft 31 basically does not move forward or backward beyond a predetermined stop position (advance / retreat movement limit). However, when the screw shaft 31 malfunctions due to a failure of the position detection device and moves backward beyond a predetermined stop position, the rear end portion (the end portion on the other side in the axial direction) of the screw shaft 31 becomes the shaft case 35. The shaft case 35 may be deformed or damaged by colliding with the bottom portion 35b. Further, it cannot be denied that the rear end portion of the screw shaft 31 may collide with the bottom portion 35b of the shaft case 35 due to a handling error during the assembling work of the screw shaft 31, and the shaft case 35 may be deformed or damaged.

Therefore, in the present embodiment, as shown in FIG. 4, the guide collar 72 (outer peripheral surface 72a) made of an elastic material does not abut on the bottom portion 35b of the shaft case 35 with the screw shaft 31 (the other end surface 31c). ) And the contact surface 35b2 that can be brought into contact with each other in the axial direction. In the illustrated example, the contact surface 35b2 is provided on the radial outer side of the inner bottom surface 35b1 of the bottom portion 35b, and is formed as a stepped surface located on one side in the axial direction with respect to the inner bottom surface 35b1. In this case, as shown in the illustrated example, when the guide collar 72 is in axial contact with the contact surface 35b2 provided on the bottom 35b of the shaft case 35, the inner bottom surface 35b1 and the screw shaft 31 of the shaft case 35 facing each other are in contact with each other. Since an axial gap is formed between the screw shaft 31 and the other end surface 31c, the screw shaft 31 and the bottom portion 35b of the shaft case 35 are held in a non-contact state.

In short, according to the above configuration, when the screw shaft 31 linearly moves in the direction in which the screw shaft 31 approaches the bottom portion 35b of the shaft case 35, the guide collar 72 provided on the screw shaft 31 precedes the screw shaft 31. In axial contact with the bottom 35b of the shaft case 35. Since the guide collar 72 is made of an elastic material such as a rubber material, even if the guide collar 72 collides with the bottom portion 35b of the shaft case 35, the impact load is absorbed and relaxed. As a result, it is possible to effectively prevent the shaft case 35 from being deformed or damaged. Further, since the guide collar 72, which is one of the components of the existing rotation regulation unit 70, is provided with a cushioning function, it is possible to avoid an increase in cost that may occur when a separate cushioning member is attached to the screw shaft 31. Therefore, according to the present invention, it is possible to prevent the shaft case 35 from being deformed or damaged without causing a particular increase in cost.

Although the electric actuator 1 according to the embodiment of the present invention has been described above, the electric actuator 1 can be appropriately modified without departing from the gist of the present invention.

For example, in the embodiment described above, a part of the guide collar 72 (outer peripheral surface 72a) protrudes to the other side in the axial direction from the end surface 31c of the screw shaft 31, but the bottom portion 35b of the shaft case 35 When the guide collar 72 comes into contact with the contact surface 35b2 provided on the shaft case 35, the bottom portion 35b of the shaft case 35 and the screw shaft 31 do not abut in the axial direction (the inner bottom surface 35b1 and the screw shaft 31 of the bottom portions 35b facing each other). The axial relative position of the guide collar 72 with respect to the screw shaft 31 can be arbitrarily set as long as an axial gap is formed between the two end faces 31c. That is, as shown in FIG. 5, the guide collar 72 may be provided so that the entire guide collar 72 is located on one side in the axial direction with respect to the end surface 31c of the screw shaft 31, and its outer peripheral surface 72a is the end surface of the screw shaft 31. It may be provided so as to be located on the same surface as 31c (not shown).

Further, in the embodiment described above, the pair of guide collars 72, 72 are rotatably supported at both ends in the axial direction of one support pin 71 (as the support pin 71, both ends in the axial direction thereof). However, the pair of guide collars 72 and 72 can also be rotatably supported by two support pins 71 mounted on the screw shaft 31, respectively. (Not shown). Further, the guide collar 72 and the axial guide groove 35c into which the guide collar 72 is fitted may be provided at three or more locations separated in the circumferential direction.

Further, in the embodiment described above, the motion conversion mechanism portion 3 is composed of the ball screw 30, but in the motion conversion mechanism portion 3, the ball 33 and the frame 34 are omitted, and substantially on the screw shaft 31 and its outer periphery. It is also possible to use a so-called sliding screw, which is composed of only a rotatably fitted nut 32. Further, in the embodiment described above, the speed reduction mechanism unit 9 is provided in the drive unit 2, but in the present invention, the speed reduction mechanism unit 9 is omitted (the drive unit 2 is substantially composed of only the motor unit 8). It can also be applied to the electric actuator 1.

The present invention is not limited to the above-described embodiments, and it is needless to say that the present invention can be carried out in various forms without departing from the gist of the present invention. Indicated by the scope of claims and further includes the equal meanings set forth in the claims, and all modifications within the scope.

1 Electric actuator 2 Drive part 3 Motion conversion mechanism part 10 Electric motor 31 Screw shaft 32 Nut 35 Shaft case 35b Bottom 35b 2 Contact surface 35c Guide groove 70 Rotation regulation part 71 Support pin (support shaft)
72 Guide collar (rotating body)

Claims (4)

A drive unit having an electric motor and a motion conversion mechanism unit that converts the rotational motion of the drive unit into a linear motion are provided, and the motion conversion mechanism unit includes a nut that rotates in response to the rotational motion of the drive unit. In an electric actuator having a screw shaft that moves forward and backward in the axial direction in a state where rotation around the axis is restricted as the nut rotates, and the screw shaft is housed in a bottomed tubular shaft case.
The rotation regulating portion that regulates the rotation of the screw shaft is formed of an axial guide groove formed on the inner peripheral surface of the shaft case and an elastic material, and a radial support shaft provided on the screw shaft. It has a rotating body fitted in the guide groove in a state where it can rotate around.
An electric actuator characterized in that a contact surface is provided on the bottom of the shaft case so that the screw shaft does not come into contact with the screw shaft in the axial direction but can come into contact with the rotating body in the axial direction. The electric actuator according to claim 1, wherein the rotating body is provided at a plurality of locations separated in the circumferential direction of the screw shaft. The electric motor according to claim 1 or 2, wherein the support shaft is composed of a support pin mounted on the screw shaft, and the rotating body is composed of a cylindrical member rotatably supported by the support pin. Actuator. The electric actuator according to any one of claims 1 to 3, wherein the screw shaft is arranged in parallel with the rotation shaft of the electric motor.

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