JP2022054862A - Electric actuator - Google Patents

Abstract

To improve the durability and operational stability of an electric actuator.SOLUTION: An electric actuator 1 has an electric motor 2, a screw shaft 7 that is driven rotationally by the output of the electric motor, and a nut 8 that is screwed to the screw shaft. The rotational motion of the screw shaft 7 is converted into a linear motion of a nut 8. Switching from start to stop of power supply to the electric motor 2 is performed on the basis of the elapsed time since the start of power supply. The nut 8, which performs a linear motion, is brought into contact with an area of a first thrust bearing 50 supported by the screw shaft 7 that is allowed to rotate relative to the screw shaft 7.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electric actuator.

In recent years, motorization has been progressing in order to save labor or reduce fuel consumption of vehicles and the like. For example, in automobiles, a system for operating an automatic transmission, a brake, or steering by the power of an electric motor has been developed and put on the market.

As one of the actuators used for such an application, Patent Document 1 below discloses an electric actuator that converts the output of an electric motor into a linear motion of a linear motion member.

Japanese Unexamined Patent Publication No. 2019-97352

In the electric actuator described in Patent Document 1, protrusions are provided on both end faces of the nut, which is a linear motion member, in the axial direction, and protrusions are provided on the end faces of the raceway rings of the thrust bearings facing these end faces in the axial direction. There is. By engaging these protrusions in the rotational direction, the rotation of the screw shaft is restricted, and the axial movement of the nut beyond that is restricted.

However, a collision load is generated when the protruding portion of the nut and the protruding portion of the raceway ring are engaged in the rotational direction. Therefore, this impact load may damage or deform the motion conversion mechanism and the components of the electric motor. Further, since a large rotational torque acts on the nut immediately after the protrusions are engaged with each other, the male screw of the screw shaft may be caught in the female screw of the nut. When this biting occurs, the nut cannot be moved in reverse even if the electric motor is driven in reverse, and the operational stability of the electric actuator deteriorates.

Therefore, an object of the present invention is to improve the durability and operational stability of the electric actuator.

In order to solve the above problems, the present invention includes an electric motor, a rotating member rotationally driven by the output of the electric motor, and a linear motion member screwed with the rotating member, and causes the rotational movement of the rotating member. In an electric actuator having a motion conversion mechanism that converts the linear motion of the linear motion member into a linear motion and a stationary member that supports the rotary member, switching from the start to the stop of the power supply to the electric motor is the start of the power supply. The linear motion member that performs the linear motion is brought into contact with the region of the first thrust bearing supported by the rotary member that is allowed to rotate relative to the rotary member. It is a feature.

In this way, by bringing the linear motion member into contact with the region of the first thrust bearing supported by the rotary member where relative rotation with respect to the rotary member is permitted, the linear motion member with respect to the rotary member immediately after the contact is brought into contact with the linear motion member. Relative rotation is allowed. Therefore, the impact load acting on the rotating member and the linear motion member immediately after the contact can be reduced, and the deformation and damage of each part of the electric actuator can be avoided. Further, since the rotational torque acting on the linear motion member immediately after the contact is reduced, it is possible to prevent the screws from getting caught between the linear motion member and the rotary member. Therefore, after that, even when the electric motor is reversely driven, the linear motion member can be reliably moved linearly in the opposite direction.

As the first thrust bearing, it is preferable to use a rolling bearing having a plurality of rolling elements. By using the rolling bearing as the first thrust bearing in this way, the rotational torque acting on the linear motion member immediately after the contact between the linear motion member and the first thrust bearing can be reduced, and the impact load can be reduced or the linear motion can be performed. It is possible to more effectively prevent the screws from getting caught between the member and the rotating member.

It is preferable to interpose the second thrust bearing between the stationary member and the rotating member.

In this case, it is preferable that the bearing ring on the rotating side of the first thrust bearing and the bearing ring on the rotating side of the second thrust bearing are brought into contact with each other in the axial direction, or both bearing rings are integrated.

As a result, when the linear motion member and the first thrust bearing come into contact with each other, most of the axial force of the linear motion member propagates directly from the first thrust bearing to the second thrust bearing without going through the rotating member, and is stationary. Supported by a member. In this case, since the axial force from the linear motion member hardly acts on the rotating member, it is possible to avoid deformation or damage of each part of the electric actuator due to the axial force acting on the rotating member.

In order to strictly control the position of the stroke end of the linear motion member, it is desirable to stop the power supply to the electric motor after the linear motion member comes into contact with the first thrust bearing.

According to the present invention, the present invention can improve the durability and operational stability of the electric actuator.

It is a perspective view which shows the internal structure of the electric actuator which concerns on 1st Embodiment. It is sectional drawing of the electric actuator which concerns on 1st Embodiment. It is sectional drawing of the electric actuator which concerns on 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each drawing for explaining the present invention, components such as members or components having the same function or shape are designated by the same reference numerals as much as possible. Therefore, the description of the components once described will be omitted.

FIG. 1 is a perspective view showing the internal structure of the electric actuator according to the first embodiment of the present invention, and FIG. 2 is a sectional view of the electric actuator.

As shown in FIG. 1, the electric actuator 1 according to the present embodiment includes an electric motor 2, a speed reducer 3, a sliding screw mechanism 4, a swing mechanism 5, an output shaft 14, a circuit board 30, and a housing. It is equipped with 6.

The housing 6 as a stationary member is an exterior member that houses various internal parts such as an electric motor 2, a speed reducer 3, a sliding screw mechanism 4, a swing mechanism 5, an output shaft 14, and a circuit board 30. In the present embodiment, the housing 6 is divided into two by a plane parallel to the axis of the screw shaft 7. The housing 6 is formed by connecting the two housing divisions 60 in a state where the mating surfaces are butted against each other. The housing divided bodies 60 are assembled between the mating surfaces via a sealing member (not shown). As a result, the internal space of the housing 6 is sealed, and foreign matter such as dust and water is prevented from entering the housing 6.

In particular, when the mating surface of the housing split 60 (the cross-hatched portion in FIG. 2) is a flat surface without a step as in the present embodiment, there is some difference between the mating surfaces of the housing split 60 at the time of assembly. Even if there is a misalignment, it is difficult for gaps to occur between the mating surfaces, and it is easy to ensure airtightness. The sealing member for sealing the housing 6 may be a solid sealing material such as an O-ring, a rubber sheet, a resin sheet, a joint sheet, or a metal gasket, or a liquid sealing member such as a liquid gasket.

The electric motor 2 is a small DC motor such as a brushed motor or a brushless motor. The electric motor 2 is held by a motor holder 16 arranged between the electric motor 2 and the speed reducer 3. In the present embodiment, the electric motor 2 and the motor holder 16 are fixed by a plurality of bolts 17 (see FIG. 2) as fixing members. A pair of motor terminals 2b project from the end of the electric motor 2 on the side opposite to the speed reducer 3 side. Each motor terminal 2b is connected to a pair of board terminals 31 of the circuit board 30 via a lead wire 32. A holding member 40 fixed to the housing 6 is in contact with the end of the electric motor 2 opposite to the speed reducer 3 side. The motor holder 16 and the holding member 40 position the electric motor 2 in the axial direction.

The circuit board 30 is a control board that controls the drive of the electric motor 2. The circuit board 30 is provided with a switching element (not shown) for turning on / off the power supply from the external power supply to the electric motor 2 and switching the power supply circuit. The electric motor 2 rotates forward or reverse by switching the power supply circuit based on a signal from a control unit (not shown) by the switching element.

The sliding screw mechanism 4 is a first motion conversion mechanism that converts the rotary motion of the electric motor 2 transmitted via the speed reducer 3 into a linear motion. As shown in FIG. 2, the sliding screw mechanism 4 has a screw shaft 7 as a rotating member and a nut 8 as a linear motion member. Threaded grooves (male threads and female threads) that are screwed together are formed on the outer peripheral surface of the screw shaft 7 and the inner peripheral surface of the nut 8. Therefore, when the screw shaft 7 rotates, the nut 8 linearly moves in the axial direction of the screw shaft 7. A detent mechanism (not shown) that regulates the rotation of the nut 8 is provided between the nut 8 and the housing 6. Both ends of the screw shaft 7 in the axial direction are rotatably supported with respect to the housing 6 by a pair of bearing units 19.

The swing mechanism 5 is a second motion conversion mechanism that converts the linear motion of the sliding screw mechanism 4 into a swing motion or a rotary motion around an axis different from the axial direction of the electric motor 2. As shown in FIG. 1, the swing mechanism 5 has a swing member 11 provided on the output shaft 14 and a columnar protrusion 12 provided on the nut 8 of the sliding screw mechanism 4. In the present embodiment, the protrusion 12 and the swing member 11 are provided on both sides of the nut 8 with the nut 8 interposed therebetween. The swing member 11 is integrally attached to the output shaft 14. Therefore, when the swing member 11 swings or rotates, the output shaft 14 swings or rotates together with the swing member 11. The protrusion 12 is a connecting portion that connects the swing member 11 and the nut 8 in an interlockable manner. The protrusion 12 is inserted into the elongated hole 11c provided in the swing member 11.

The output shaft 14 is provided with a connecting hole 14a in which a plurality of irregularities (splines) are formed on the inner peripheral surface. The connecting hole 14a is a hole for inserting an operation shaft provided in an operation target (not shown). The operating shaft is inserted into the connecting hole 14a, and the operating shaft and the connecting hole 14a are spline-fitted, so that the operating shaft and the output shaft 14 are integrally rotatably connected.

The speed reducer 3 is a speed reduction mechanism that reduces the rotation of the electric motor 2. In this embodiment, a two-stage planetary speed reducer 20 is used as the speed reducer 3. Specifically, as shown in FIG. 2, the planetary speed reducer 20 includes a first sun gear 21, a first planetary gear 22, a first carrier 23, a second planetary gear 24, and a second carrier 25. It has a ring gear 26.

The ring gear 26 is an annular internal gear having a plurality of teeth on the inner peripheral surface, and is a member that functions as a first-stage and second-stage orbital ring that guides the first planetary gear 22 and the second planetary gear 24. Of the ring gear 26, the portion that meshes with the first planetary gear 22 is the portion that functions as the first-stage orbital ring, and the portion that meshes with the second-stage planetary gear 24 is the portion that functions as the second-stage orbital ring. The first-stage orbital ring and the second-stage orbital ring may be separate bodies.

The first sun gear 21 is an external gear having a plurality of teeth on the outer peripheral surface, and is a member that functions as a first-stage input rotating body to which a driving force from the electric motor 2 is input. The first sun gear 21 is attached to the rotating shaft 2a of the electric motor 2. When the electric motor 2 rotates, the first sun gear 21 also rotates together with the rotating shaft 2a of the electric motor 2.

The first planetary gear 22 is an external gear having a plurality of teeth on the outer peripheral surface, and is a member that functions as a first-stage planetary rotating body. A plurality of first planetary gears 22 are interposed between the first sun gear 21 and the ring gear 26, and are arranged so as to mesh with the first sun gear 21 and the ring gear 26. Further, each first planetary gear 22 is rotatably attached to the first carrier 23.

The first carrier 23 is a member that also serves as a first-stage output rotating body and a second-stage input rotating body. In the present embodiment, the first carrier 23 has a cylindrical portion 23a and a flange portion 23b protruding from the cylindrical portion 23a in the outer diameter direction. A first planetary gear 22 is rotatably attached to the flange portion 23b. On the other hand, the cylindrical portion 23a is provided with a gear portion 23c that meshes with the second planetary gear 24. The portion that functions as the output rotating body of the first stage (flange portion 23b) and the portion that functions as the input rotating body of the second stage (cylindrical portion 23a) may be separate bodies connected to each other.

Further, in the present embodiment, the rotating shaft 2a of the electric motor 2 is inserted into the cylindrical portion 23a of the first carrier 23 in order to prevent the positional deviation (shake) of the first carrier 23 in the radial direction. That is, in the present embodiment, the rotating shaft 2a of the electric motor 2 also serves as a bearing that rotatably supports the first carrier 23.

The second planetary gear 24 is an external gear having a plurality of teeth on the outer peripheral surface, and is a member that functions as a second-stage planetary rotating body. A plurality of second planetary gears 24 are interposed between the cylindrical portion 23a of the first carrier 23 and the ring gear 26, and are arranged so as to mesh with the gear portion 23c of the cylindrical portion 23a and the ring gear 26.

The second carrier 25 is a member that functions as a second-stage output rotating body. Similar to the first carrier 23, the second carrier 25 according to the present embodiment has a cylindrical portion 25a and a flange portion 25b protruding from the cylindrical portion 25a in the outer diameter direction. However, a gear portion is not provided on the outer peripheral surface of the cylindrical portion 25a of the second carrier 25. Instead, the radial bearing 9 of the bearing unit 19 that supports the screw shaft 7 is mounted on the outer peripheral surface of the cylindrical portion 25a of the second carrier 25. A second planetary gear 24 is rotatably attached to the flange portion 25b of the second carrier 25.

Further, one end of the screw shaft 7 in the axial direction is connected to the second carrier 25. In the present embodiment, splines extending in the axial direction are formed on the inner peripheral surface of the cylindrical portion 25a of the second carrier 25 and the outer peripheral surface on the one end side of the screw shaft 7. By fitting these splines together, the screw shaft 7 and the second carrier 25 are integrally rotatably connected to each other.

Each bearing unit 19 has a radial bearing 9, a thrust bearing 10 (second thrust bearing), and a bearing holder 18 that supports these bearings 9 and 10. The bearing holder 18 is a stationary member fixed to the housing 6. Hereinafter, the configurations of the radial bearing 9 and the second thrust bearing 10 will be described. In the following, the structures of the radial bearing 9 and the second thrust bearing 10 located on the right side of the drawing (the side away from the electric motor 2) of FIG. 2 will be described as an example, but unless otherwise specified, the left side of the drawing. The radial bearing 9 and the second thrust bearing 10 located in have the same configuration.

The radial bearing 9 of the present embodiment is composed of a rolling bearing such as a deep groove ball bearing. The radial bearing 9 includes an inner ring 9a, an outer ring 9c, and a plurality of rolling elements (balls) 9b arranged between the inner ring 9a and the outer ring 9c. The inner ring 9a is fixed to the outer peripheral surface of the screw shaft 7 by means such as press fitting, and the outer ring 9c is fixed to the inner peripheral surface of the bearing holder 18 by means such as press fitting. The radial bearing 9 rotatably supports the screw shaft 7 with respect to the housing 6 as a stationary member in the radial direction.

The second thrust bearing 10 of the present embodiment is composed of a needle roller bearing. The second thrust bearing 10 includes a first raceway ring 10a, a second raceway ring 10b, and a plurality of rolling elements (needle-shaped rollers) 10c arranged between the two raceway wheels 10a and 10b. The first raceway ring 10a is fixed to the screw shaft 7 to form a rotating member. The second raceway ring 10b is fixed to the bearing holder 18 as a stationary member. The second thrust bearing 10 rotatably supports the screw shaft 7 with respect to the housing 6 in the thrust direction.

Subsequently, the operation of the electric actuator according to the present embodiment will be described.

When electric power is supplied from the external power source to the electric motor 2, the electric motor 2 rotates in the forward direction or in the reverse direction, so that the rotational motion is transmitted from the electric motor 2 to the planetary reducer 20 (reducer 3). That is, when the rotating shaft 2a of the electric motor 2 rotates, the first sun gear 21 connected to the rotating shaft 2a rotates integrally. As a result, each of the first planetary gears 22 that mesh with the first sun gear 21 starts to rotate. Then, each first planetary gear 22 revolves along the ring gear 26 while rotating. At this time, the revolution motion of each first planetary gear 22 is output as the rotational motion of the first carrier 23, so that the rotation is decelerated.

Further, as the first carrier 23 rotates, each of the second planetary gears 24 that mesh with the first carrier 23 starts to rotate. As a result, each second planetary gear 24 revolves along the ring gear 26 while rotating. At this time, the revolution motion of each second planetary gear 24 is output as the rotational motion of the second carrier 25, so that the rotation is further decelerated.

The rotation decelerated as described above is transmitted from the speed reducer 3 to the sliding screw mechanism 4. That is, when the second carrier 25 of the planetary reducer 20 rotates, the screw shaft 7 of the sliding screw mechanism 4 rotates integrally with the second carrier 25. When the screw shaft 7 rotates, the nut 8 moves linearly with the rotation of the screw shaft 7. In the present embodiment, when the electric motor 2 rotates in the forward direction, the nut 8 advances in the direction of the arrow A1 in FIG. 2, and when the electric motor 2 rotates in the reverse direction, the nut 8 moves in the direction of the arrow A2 in FIG. fall back.

When the nut 8 moves forward or backward, the protrusion 12 (see FIG. 1) provided on the nut 8 pushes and moves the swing member 11, and the swing member 11 swings in the direction of arrow B1 or the direction of arrow B2 in FIG. Or rotate. Then, when the output shaft 14 swings or rotates integrally with the swing member 11, the linear motion of the nut 8 rotates in a direction different from that of the rotation shaft 2a of the electric motor 2 (axis rotation of the output shaft 14). It is output as a swinging motion or a rotational motion of. In the present embodiment, since the output shaft 14 is arranged in a direction orthogonal to the rotation shaft 2a of the electric motor 2, the rotational movement of the electric motor 2 is about an axis orthogonal to the rotation shaft 2a of the electric motor 2. It is output as a rotary motion of.

Switching from the start of power supply to the electric motor 2 to the stop of power supply is performed based on the elapsed time from the start time of power supply. That is, when the power supply to the electric motor 2 is started (motor ON), the counting is started at the same time as the timing of the power supply start, and the power supply to the electric motor 2 is stopped when a predetermined fixed time elapses. (Motor OFF). The time from the start to the stop of the power supply is the time required for the nut 8 to move from one stroke end to the other stroke end. The same control is performed not only when the electric motor 2 is rotated in the forward direction (the nut 8 moves in the A1 direction) but also when the electric motor 2 is rotated in the opposite direction (the nut 8 moves in the A2 direction).

Therefore, in the electric actuator 1 of the present embodiment, the nut 8 reciprocates only between the two predetermined stroke ends, and the nut 8 does not stop at any intermediate position between the two stroke ends. .. The control of the electric motor 2 described above is performed by the control circuit provided on the substrate 30.

When the nut 8 is reciprocated in this way, it is conceivable that the sensor detects that the nut has reached the two stroke ends, and at the same time as receiving this detection signal, the power supply to the electric motor is stopped. However, in such a structure, a sensor is required, so that the cost of the electric actuator is high. In the present embodiment, since the sensor for detecting the axial position of the nut 8 is omitted, the cost of the electric actuator 1 can be reduced.

As described above, since the position of the stroke end of the nut 8 cannot be accurately determined only by starting and stopping the power supply to the electric motor 2, it is preferable to mechanically determine the stroke end of the nut 8. In the present embodiment, in order to mechanically determine the position of the stroke end, a stopper for restricting the reciprocating movement of the nut 8 is provided, and the first thrust bearing 50 is used as this stopper.

The first thrust bearing 50 is composed of a rolling bearing having a plurality of rolling elements, for example, a needle roller bearing with a cage using a needle roller as the rolling element. The first thrust bearing 50 is supported by the screw shaft 7. Specifically, the first raceway ring 10a fixed to the screw shaft 7 is used as a raceway ring on one side in the axial direction of the first thrust bearing 50 (the side opposite to the side facing the nut 8 in the axial direction). That is, in the first thrust bearing 50 and the second thrust bearing 10, a raceway ring on the rotation side is integrally formed. Of the first thrust bearing 50, the raceway ring on the other side in the axial direction (opposite side to the nut 8) is omitted.

As shown in FIG. 2, in the first thrust bearing 50 on the electric motor 2 side, a flange portion 7a extending in the outer radial direction is provided on the screw shaft 7, and the flange portion 7a is provided on one side (the side facing the nut 8). It is used as a raceway ring on the opposite side in the axial direction. The flange portion 7a may be formed integrally with the screw shaft 7 or may be formed of another member fixed to the screw shaft 7. In this case, the flange portion 7a, which is a member separate from the screw shaft 7a, is also a rotating member.

In the first thrust bearing 50, the first raceway ring 10a and the flange portion 7a are on the rotation side that rotates integrally with the screw shaft 7. On the other hand, the outer peripheral surface of the needle-shaped roller located at the farthest position in the axial direction from the first raceway ring 10a, in other words, the virtual plane in the direction orthogonal to the axis of the screw shaft 7, and each of the first thrust bearing 50. Of the outer peripheral surface of the needle-shaped roller, the contact point between the first raceway ring 10a and the non-contact outer peripheral surface is a region where relative rotation with respect to the screw shaft 7 is permitted. Therefore, by bringing the nut 8 into contact with this region (the outer peripheral surface of the needle-shaped roller), the relative rotation of the screw shaft 7 with respect to the nut 8 is allowed immediately after the contact.

In this case, even when the nut 8 and the first thrust bearing 50 come into contact with each other, no impact load acts on the screw shaft 7 and the nut 8, thereby causing electric actuators such as the electric motor 2, the reduction gear 3, and the swing mechanism 5. 1 It is possible to prevent damage and deformation of each part. Further, since the rotational torque acting on the nut 8 becomes small when the nut 8 and the first thrust bearing 50 come into contact with each other, it is possible to prevent the male screw of the screw shaft 7 from being caught by the female screw of the nut 8. Therefore, after that, even when the electric motor 2 is driven in the reverse direction, the nut 8 can be reliably moved linearly in the opposite direction.

To ensure that the nut 8 comes into contact with the first thrust bearing 50, power is supplied to the electric motor so that the power supply to the electric motor 2 is stopped after the nut 8 comes into contact with the first thrust bearing 50. It is preferable to set the time.

In this case, when the nut 8 and the first thrust bearing 50 come into contact with each other, the electric motor 2 is continuously supplied with power (motor ON state), so that the nut 8 and the first thrust bearing 50 are in a state of being continuously supplied. Although the collision speed is high, it is possible to obtain the effect of avoiding damage / deformation or malfunction of each part of the electric actuator 1 by the configuration already described even in the case of a collision at such a high speed.

On the other hand, in Patent Document 1 described above, protrusions are provided on the end face of the first raceway ring 10a of the second thrust bearing 10 and the end face of the nut 8 in the present embodiment, and the protrusions are engaged with each other in the rotational direction. The structure to be made is disclosed. In this case, when the first raceway ring and the nut are in contact with each other (when the protruding portions are engaged with each other), a large impact load acts on the nut and the screw shaft. Further, at the time of this contact, relative rotation between the first raceway ring and the nut is not allowed, so that a large rotational torque acts on the nut at the moment when the protruding portions engage with each other. Therefore, the female screw of the nut and the male screw of the screw shaft may get caught.

Further, in the present embodiment, the raceway ring on the rotation side of the first thrust bearing 50 and the raceway ring 10a on the rotation side of the second thrust bearing 10 are integrated. Therefore, when the nut 8 and the first thrust bearing 50 come into contact with each other, most of the axial force of the nut 8 propagates directly from the first thrust bearing 50 to the second thrust bearing 10 without going through the screw shaft 7. It is supported by the housing 6 via the bearing holder 18. In this case, since the axial force from the nut 8 hardly acts on the screw shaft 7, it is possible to prevent the speed reducer 3 and the electric motor 2 from being deformed or damaged due to the axial force acting on the screw shaft 7. This effect is obtained when the raceway ring on the rotation side of the first thrust bearing 50 and the raceway ring 10a on the rotation side of the second thrust bearing 10 are used as separate members, and both raceway wheels are brought into axial contact with each other (electricity in FIG. 2). The same can be obtained for the first thrust bearing 50 and the second thrust bearing 10 on the motor 2 side).

FIG. 3 shows a second embodiment of the present invention. In this second embodiment, a ball bearing with a cage is used as the first thrust bearing 50. Since the other configurations of this exception are common to the first embodiment shown in FIGS. 1 and 2, duplicate description will be omitted.

The present invention is not limited to the above-described embodiment. Of course, various changes can be made without departing from the gist of the invention.

For example, the speed reducer 3 that reduces the rotation of the electric motor is not limited to the two-stage planetary speed reducer 20 as described above, and may be a one-stage planetary speed reducer. Further, the speed reducer 3 is not limited to the planetary gear reducer that transmits the driving force via the gear, and may be a so-called traction drive type planetary speed reducer that transmits the driving force via the rollers. In addition, a parallel axis speed reducer can also be used as the speed reducer 3.

Further, the first motion conversion mechanism that converts the rotational motion of the electric motor 2 into a linear motion is not limited to the sliding screw mechanism 4 as described above, but may be a ball screw mechanism or the like. Further, the second motion conversion mechanism that converts the linear motion of the first motion conversion mechanism into a swing motion or a rotary motion around an axis different from the axial direction of the electric motor is limited to the swing mechanism 5 as described above. Instead, it may be a rack and pinion mechanism or the like.

Further, the electric actuator according to the present invention may not have at least one of the speed reducer 3 and the second motion conversion mechanism.

Further, in the above embodiment, the raceway ring on the other side in the axial direction (the side facing the nut 8 in the axial direction) of the first thrust bearing 50 is omitted, but the same as above can be used even if this raceway ring is used. The effect of can be obtained. The raceway ring is not fixed to any of the rotating member including the screw shaft 7 and the first raceway ring 10a, and the stationary member including the housing 6 and the bearing holder 18, and is free to rotate with respect to both the rotating member and the stationary member. Is in the state of.

Further, in the above embodiment, a case where a rolling bearing having a plurality of rolling elements is used as the first thrust bearing 40, the second thrust bearing 10, and the radial bearing 9 has been exemplified, but each of these bearings is low. It can also be composed of a slide bearing made of a friction material.

1 Electric actuator 2 Electric motor 4 Sliding screw mechanism (motion conversion mechanism)
6 Housing (stationary member)
7 Screw shaft (rotating member)
8 nut (linear motion member)
10 Second thrust bearing 10a First raceway ring (rotating side raceway ring)
50 First thrust bearing

Claims (5)

A motion that includes an electric motor, a rotary member that is rotationally driven by the output of the electric motor, and a linear motion member that is screwed with the rotary member, and converts the rotary motion of the rotary member into a linear motion of the linear motion member. In an electric actuator having a conversion mechanism and a stationary member that supports the rotating member,
Switching from the start to the stop of the power supply to the electric motor is performed based on the elapsed time from the start of the power supply.
An electric actuator characterized in that a linear motion member that performs linear motion comes into contact with a region of a first thrust bearing supported by the rotary member where relative rotation with respect to the rotary member is permitted. The electric actuator according to claim 1, wherein a rolling bearing having a plurality of rolling elements is used as the first thrust bearing. The electric actuator according to claim 1 or 2, wherein a second thrust bearing is interposed between the stationary member and the rotating member. The electric actuator according to claim 3, wherein the raceway ring on the rotation side of the first thrust bearing and the raceway ring on the rotation side of the second thrust bearing are brought into contact with each other in the axial direction, or both raceway wheels are integrated. The electric actuator according to any one of claims 1 to 4, wherein the power supply to the electric motor is stopped after the linear motion member comes into contact with the first thrust bearing.

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