JP6348306B2 - Electric actuator - Google Patents

Description

  The present invention relates to an electric actuator used in a drive unit of a vehicle such as an automobile, and more particularly to an electric actuator used by converting rotation of an electric motor into linear motion through a ball screw mechanism.

  In electric actuators used in various drive units of vehicles such as automobiles, a gear mechanism such as a trapezoidal screw or a rack and pinion is generally used as a mechanism for converting the rotational movement of the electric motor into a linear linear movement. Yes. Since these conversion mechanisms involve a sliding contact portion, the power loss is large, and it is necessary to increase the size of the electric motor and increase the power consumption. Therefore, a ball screw mechanism has been adopted as a more efficient actuator.

  This electric actuator is used for a clutch mechanism or the like of an automobile transmission, and is screwed onto a ball screw shaft that is rotationally driven by a motor (not shown) as a rotational drive source, as shown in FIG. An arm 51 constituting a link mechanism is connected to the ball screw nut 50, and the other end of the arm 51 is connected to an output shaft 52 which is an output shaft. An output lever (not shown) is connected to the output shaft 52. It is attached. The upper and lower shaft ends of a ball screw shaft that is rotationally driven by a motor attached to the housing are rotatably supported by a bearing fixed to the housing.

  The arm 51 includes a first arm 53 having a hollow cylindrical shape, a second arm 54 having a cylindrical shape, and a metal (not shown) that is a slide bearing, and thus can extend and contract in the axial direction. The structure is rotatable around the axis. Then, a convex portion 55 having a central axis orthogonal to the ball screw axis is provided on the outer diameter of the ball screw nut 50, and the arm 51 is formed by the convex portion 55 and a metal 56 that is a slide bearing attached to the first arm 53. The ball screw nut 50 is rotatably connected. The metal 56 is held on the first arm 53 by a plate 58 and a screw 59 that fixes the plate 58 to the first arm 53. Further, since a through hole is provided in the output shaft 52 and the pin 57 is fixed to the first arm 53 through this hole, the second arm 54 is rotatably connected around the pin 57 as an axis.

  The ball screw shaft is rotationally driven by a motor, and the ball screw nut 50 linearly moves on the ball screw shaft along with the rotational motion. The convex portion 55 provided on the ball screw nut 50 supports the first arm 53 in a rotatable manner, and the arm 51 that connects the ball screw nut 50 and the output shaft 52 can extend and contract in the axial direction. When the nut 50 moves linearly, the output shaft 52 rotates, and the output lever provided on the output shaft 52 swings. The actuator is operated by connecting a clutch mechanism to the output lever.

  As described above, the structure in which the arm 51 can extend and contract in the axial direction and rotate around the arm 51 can absorb the positional deviation between the ball screw nut 50 and the output shaft 52, and the inclination of the arm 51 and the ball screw nut 50 can be absorbed. Since the linearity of the ball screw shaft and the ball screw nut 50 is ensured without being affected by the accuracy of the convex portion 55 bearing and without special balance adjustment, the ball screw is operated with high efficiency. be able to.

  In addition, since the power transmission loss is minimized by configuring the linear and rotational motion portions of the link mechanism with bearings made of metal 56, a small and high-power actuator can be provided (see, for example, Patent Document 1).

  On the other hand, there has been proposed a structure that suppresses the wear of the metal 56 mounted on the convex portion 55 of the ball screw nut 50 while ensuring the smooth operation of this type of arm 51. As shown in FIG. 6, the ball screw mechanism is arranged so as to surround a screw shaft 63 having a screw groove 63 a formed on the outer periphery, and a screw groove (not shown) on the inner periphery. The cylindrical nut 60 is formed, and a plurality of balls (not shown) that are arranged so as to be able to roll between both screw grooves. A tube 64 serving as a circulation member is attached to the outer periphery of the nut 60.

  A screw shaft 63 is arranged coaxially with the cylindrical hole Ha of the housing H. One end of a screw shaft 63 rotatably supported by a bearing 65 with respect to the cylindrical hole Ha is connected to a motor (not shown) via a coupling C, and moves in the axial direction with respect to the cylindrical hole Ha of the housing H. Unsupported and rotatable. A connecting member 61 is attached to the nut 60. The connecting member 61 is attached to each of a circular tubular main body 61a extending in a direction orthogonal to the axis of the nut 60, a pair of arms 61b extending from both ends of the main body 61a, and the distal ends of the arms 61b. It consists of the spherical seat 61c (refer FIG. 7) arrange | positioned. The main body 61a is connected to, for example, a drive shaft S of a variable valve mechanism (not shown).

  As shown in FIG. 7, each spherical seat 61c forms a spherical surface 61d on the opposite surface. A pair of spherical surfaces 60 a is formed on the outer peripheral surface of the nut 60 so as to face the pair of spherical seats 61 c. A spherical body 62 is disposed between the spherical surfaces 61d and 60a. Here, when R is the radius of the spherical surfaces 61d and 60a and D is the diameter of the sphere 62, 0 <R−D / 2 ≦ 0.02 mm is established. By utilizing this clearance, a thin film of lubricant is interposed between the spherical surfaces 61d, 60a and the sphere 62, thereby reducing wear during sliding of both.

  Further, since the spherical body 62 sandwiched between the spherical surface 61d of the connecting member 61 and the spherical surface 60a of the nut 60 and engaged therewith is directed, when the pressing force is applied from the connecting member 61 to the nut 60, the spherical surface is provided. Surface contact occurs between 61d, 60a and the sphere 62, the surface pressure is reduced, and wear of the connecting member 61 and the nut 60 can be avoided (see, for example, Patent Document 2).

JP 2011-112193 A JP 2006-183699 A

  In such a conventional ball screw mechanism, since the spherical body 62 is sandwiched between the spherical surface 61 d of the connecting member 61 and the spherical surface 60 a of the nut 60, the surface pressure is reduced by surface contact, and wear of the connecting member 61 and the nut 60 is avoided. Features that can be done. However, such a structure is complicated, and the manufacturing and assembly man-hours are complicated, resulting in an increase in cost. In addition, foreign matter such as wear powder is caught in the gap between the spherical surfaces 61d, 60a and the sphere 62. There is a risk that uneven wear may occur and smooth swing motion may be hindered.

  The present invention has been made in view of such circumstances, and eliminates such conventional problems, while reducing the weight and size while reducing the cost and suppressing the wear of the engaging portion with the connecting member. And it aims at providing the electric actuator which can operate | move smoothly.

  In order to achieve such an object, the invention according to claim 1 of the present invention includes an electric motor attached to a housing, a main shaft of the electric motor, and a helical screw groove formed on the outer periphery. A screw shaft supported so as to be rotatable and non-movable in the axial direction with respect to the housing, and a screw-like shape that is extrapolated to the screw shaft via a number of balls and that corresponds to the screw groove of the screw shaft on the inner periphery. A ball screw formed of a nut formed with a thread groove and supported so as not to rotate and move in the axial direction; and a connecting arm having a yoke portion with a bifurcated tip. In the electric actuator that is engaged with the nut and in which the rotational movement of the electric motor is converted into the axial movement or the swinging movement of the connecting arm via the nut, a pair of circles is provided on the outer peripheral surface of the nut. A convex roller is disposed opposite to each other, and a guide roller made of a rolling bearing is fitted to the convex portion, and a U-shaped recess is formed in the yoke portion of the connecting arm. The convex part is engaged via the guide roller.

  As described above, the electric motor attached to the housing and the main shaft of the electric motor are coupled to each other, and a spiral screw groove is formed on the outer periphery, and is supported so as to be rotatable with respect to the housing and not movable in the axial direction. The screw shaft and the screw shaft are extrapolated via a large number of balls, and a spiral screw groove corresponding to the screw groove of the screw shaft is formed on the inner periphery, and is supported so as not to rotate but to be movable in the axial direction. And a connecting arm having a yoke part with a bifurcated tip, and the connecting arm is engaged with the nut, and the rotational motion of the electric motor is connected via the nut. In an electric actuator that is converted into an axial motion or a swinging motion, a pair of cylindrical convex portions are arranged opposite to each other on the outer peripheral surface of the nut, and a guide roller comprising a rolling bearing is fitted to these convex portions. At the same time, U-shaped recesses are formed in the yoke portion of the connecting arm, and these recesses and the projections of the nut are engaged via the guide roller. A wide contact range of the convex portion can be secured, for example, when the connecting arm swings, the swing angle can be set large, and the contact portion constantly changes instead of a fixed range, It is possible to provide an electric actuator that can suppress the wear of the engaging portion and can perform a smooth swinging motion as compared with the related art.

  Preferably, as in the invention described in claim 2, a pair of flat surfaces are formed facing the outer peripheral surface of the nut, the convex portions are formed on these flat surfaces, and the yoke portion of the connecting arm If the connecting arm is attached to the nut while holding the flat surface of the nut, the moment load acting on the nut is supported by the surface contact between the yoke portion of the connecting arm and the flat surface of the nut. The nut can be configured to be non-rotatable and movable in the axial direction, and the coupling arm can follow the movement of the nut in the axial direction without looseness by engaging the recess of the coupling arm with the guide roller. .

  Further, as in the third aspect of the invention, if the screw shaft and the main shaft of the electric motor are coupled so as to be able to transmit torque coaxially and detachably in the axial direction via serrations, The centering of the main shaft and the screw shaft becomes easy, and this screw shaft can be cantilevered by a single rolling bearing on the side of the non-electric motor, improving the assembly and improving the number of parts. Can be reduced to achieve lighter weight and compactness.

  Further, if an elastic member made of synthetic rubber is integrally joined to the outer peripheral surface of the outer ring of the guide roller as in the invention described in claim 4, even if an impact load is generated on the guide roller, the elastic member To improve durability and increase the friction coefficient of the outer peripheral surface that will be in contact with the recess of the connecting arm, allowing the guide roller to actively roll and reduce wear on the engaging portion. Can be suppressed.

  Further, as in the invention described in claim 5, if the outer peripheral surface of the outer ring of the guide roller is subjected to a surface treatment having a high friction coefficient, the outer peripheral surface that becomes a contact portion with the recess of the connecting arm is provided. The friction coefficient is increased, the guide roller can be actively rolled and the wear of the engaging portion can be suppressed.

  Moreover, if the said surface treatment is a phosphate membrane | film | coat process like invention of Claim 6, the rusting of a guide roller can be prevented and durability can be improved.

If the guide roller is formed of a hermetic rolling bearing as in the invention described in claim 7, leakage of the lubricating grease enclosed in the bearing to the outside, wear powder from the outside, etc. It is possible to prevent the inside of the bearing from entering, and it is possible to prevent foreign matter such as wear powder from being caught and causing uneven wear or hindering smooth operation as in the prior art. Further, as in the invention described in claim 8, if the guide roller is constituted by a rolling bearing made of a needle roller bearing, the guide roller can be actively rolled and the engagement portion is worn. Can be further suppressed.

  An electric actuator according to the present invention is coupled to an electric motor attached to a housing and a main shaft of the electric motor, and has a spiral thread groove formed on an outer periphery thereof, and is rotatable and axially movable with respect to the housing. An unsupported screw shaft, and a screw thread that is extrapolated to the screw shaft through a large number of balls, and a spiral thread groove corresponding to the thread groove of the screw shaft is formed on the inner periphery, so that the shaft cannot rotate. A ball screw composed of a nut supported so as to be freely movable in a direction, and a connecting arm having a yoke portion with a bifurcated tip. The connecting arm is engaged with the nut and rotates the electric motor. In the electric actuator in which the movement is converted into the axial movement or the swinging movement of the connecting arm via the nut, a pair of columnar convex portions are arranged opposite to each other on the outer peripheral surface of the nut. Guide rollers made of rolling bearings are fitted to these convex portions, and U-shaped recesses are formed in the yoke portion of the connecting arm, and these concave portions and the convex portions of the nut are interposed via the guide rollers. Since it is engaged, it is possible to secure a wide contact range between the recess serving as the engaging portion and the convex portion of the nut. For example, when the connecting arm swings, this swing angle should be set large. In addition, it is possible to provide an electric actuator capable of suppressing the wear of the engaging portion and suppressing the wear of the engaging portion, and capable of a smooth swinging motion as compared with the conventional case.

It is a longitudinal section showing one embodiment of an electric actuator concerning the present invention. (A) is a front view which shows the connection arm of FIG. 1, (b) is a side view of (a). (A) is a longitudinal cross-sectional view which shows the rolling bearing used for the engaging part of the nut of FIG. 1, and a connection arm, (b) is a longitudinal cross-sectional view which shows the modification of the rolling bearing of (a). It is a longitudinal cross-sectional view which shows the other modification of the rolling bearing of Fig.3 (a). It is a built-in figure which shows the conventional electric actuator. (A) and (b) are the perspective views which cut and saw a part of conventional ball screw mechanism. It is a principal part enlarged view which shows the engaging part of the nut of FIG. 5, and a connection member.

  An electric motor attached to the housing and a main shaft of the electric motor are coaxially coupled, and a helical thread groove is formed on the outer periphery, and is supported so as to be rotatable and non-movable in the axial direction with respect to the housing. The screw shaft and the screw shaft are extrapolated via a large number of balls, and a spiral screw groove corresponding to the screw groove of the screw shaft is formed on the inner periphery, so that the screw shaft is non-rotatable and can be moved in the axial direction. A ball screw made of a cylindrical nut and a connecting arm having a yoke part with a bifurcated tip, and the connecting arm is engaged with the nut, and the electric motor rotates. In the electric actuator that is converted into the swinging motion of the connecting arm via the nut, a pair of flat surfaces are formed to face the outer peripheral surface of the nut, and cylindrical convex portions are formed on these flat surfaces. The connecting arm is attached to the nut with the yoke portion of the connecting arm sandwiching the flat surface of the nut, and a guide roller comprising a rolling bearing is fitted to the convex portion. U-shaped recesses are formed in the yoke portion, and these recesses and the projections of the nut are engaged via the guide roller.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an embodiment of an electric actuator according to the present invention, FIG. 2 (a) is a front view showing a connecting arm of FIG. 1, and (b) is a side view of FIG. 3 (a) is a longitudinal sectional view showing a rolling bearing used in the engaging portion between the nut and the connecting arm in FIG. 1, and FIG. 4 (b) is a longitudinal sectional view showing a modification of the rolling bearing in FIG. These are the longitudinal cross-sectional views which show the other modification of the rolling bearing of Fig.3 (a).

  The electric actuator 1 includes an electric motor 3 attached to a housing 2, a screw shaft (output shaft) 4 having a helical thread groove 4a formed on an outer peripheral surface, and an outer periphery of the screw shaft 4. A ball screw 7 comprising a nut 5 having a spiral thread groove 5a corresponding to the thread groove 4a formed on the surface, and a large number of balls 6 accommodated so as to roll between the thread grooves 4a and 5a; A rod shaft 8 provided in parallel with the screw shaft 4 of the screw 7, and a connecting arm 9 having a base end portion 9 a fixed to an intermediate portion of the rod shaft 8 and a tip end portion 9 b engaged with the nut 5. Yes.

  The screw shaft 4 of the ball screw 7 is coupled to the main shaft 3a of the electric motor 3 through a serration 4b so as to be able to transmit torque and detachably in the axial direction. The housing 2 is formed with a bearing hole 2a, and the screw shaft 4 is supported by the rolling bearing 10 mounted in the bearing hole 2a so as not to move in the axial direction and so as to be rotatable with respect to the housing 2. On the other hand, the nut 5 is formed in a cylindrical shape by cold forging, and a pair of flat surfaces 5b and 5b are formed on opposing outer peripheral surfaces, and a columnar convex portion 11 is formed on these flat surfaces 5b and 5b.

  The rod shaft 8 is inserted into an insertion hole 2b formed in the housing 2, and is supported so as to be movable in the axial direction via bearings 12 and 12, and a base end portion 9a of the connecting arm 9 is fixed to an intermediate portion thereof. It is fixed via a screw 13. At both ends of the rod shaft 8, connecting portions 8a and 8b made of yokes connected to a push-pull cable or the like are provided.

  The connecting arm 9 is formed in a fork shape, and as shown in FIG. 2A, a screw hole 14 into which the fixing screw 13 is screwed is formed in the base end portion 9a, and a bifurcated shape is formed in the distal end portion 9b. The yoke portions 15 are formed to face each other, and the connecting arm 9 is attached to the nut 5 with the yoke portions 15 and 15 sandwiching the flat surfaces 5 b and 5 b of the nut 5. Further, as shown in (b), U-shaped recesses 9c are respectively formed in the yoke portions 15 and 15 of the connecting arm 9, and the protrusions 11 of the nut 5 are described later in these recesses 9c and 9c. It is engaged via a guide roller 16.

  With such a configuration, the nut 5 is configured to be non-rotatable and movable in the axial direction. That is, as shown in FIG. 1, the nut 5 cannot be rotated while moving the axial direction while supporting the moment load acting on the nut 5 by the surface contact between the yoke portion 15 of the connecting arm 9 and the flat surface 5b of the nut 5. The connecting arm 9 can be freely configured, and the engagement of the recess 9c of the connecting arm 9 with the guide roller 16 allows the connecting arm 9 to follow the movement of the nut 5 in the axial direction without any backlash. It can move in the axial direction corresponding to the movement of 9.

  In the present embodiment, the screw shaft 4 and the main shaft 3a are coupled via the serration 4b so as to be able to transmit torque and detachably in the axial direction. Therefore, the main shaft 3a and the screw shaft 4 of the electric motor 3 arranged coaxially. And the screw shaft 4 can be supported by a cantilever of a single rolling bearing 10 fitted on the counter-electric motor 3 side, and assemblability can be improved. At the same time, the number of parts can be reduced to reduce the weight and size of the device.

  Next, the operation of the electric actuator 1 according to the present invention will be described with reference to FIG. When the electric motor 3 is energized, for example, the screw shaft 4 is rotated forward by the positive rotation of the main shaft 3a driven by the electric motor 3, and the nut 5 is linearly moved to the right in the drawing by the rotation of the screw shaft 4. At this time, since the distal end portion 9b of the connecting arm 9 connected to the rod shaft 8 is engaged with the nut 5 constituting the ball screw 7, the connecting arm 9 follows the linear movement of the nut 5 in the right direction. The rod shaft 8 linearly moves to the right along with the movement of the connecting arm 9. On the other hand, when the nut 5 moves linearly in the left direction in the drawing due to the reverse rotation of the main shaft 3a driven by the electric motor 3, the connecting arm 9 moves linearly in the left direction. As the connecting arm 9 moves, the rod shaft 8 moves to the left. Move straight in the direction.

  Here, the convex portion 11 of the nut 5 is engaged through a guide roller 16, and the guide roller 16 is constituted by a rolling bearing made of a deep groove ball bearing as shown in FIG. Yes. The guide roller 16 includes an outer ring 17 having an outer rolling surface 17a formed on the inner periphery, an inner ring 18 having an inner rolling surface 18a opposed to the outer rolling surface 17a on the inner periphery, and both of these rollings. A plurality of balls 20 are rotatably accommodated by a cage 19 between the surfaces 17a and 18a, and shield plates 21 and 21 are attached to both ends. Then, a projection of a nut (not shown) is fitted to the inner diameter of the inner ring 18.

  As described above, since the guide roller 16 is formed of a sealed deep groove ball bearing, the leakage of the lubricating grease sealed inside the bearing and the prevention of wear powder and the like from entering the bearing from the outside are prevented. As a result, foreign particles such as wear powder do not get caught and wear is not obstructed or smooth operation is not hindered. Deep groove ball bearings are also available as general rolling bearings. The assembly man-hours can be simplified and the cost can be reduced.

  Further, by using a rolling bearing as the guide roller 16, for example, when this type of electric actuator is used in a drive unit such as an automatic control type manual transmission or a variable valve mechanism of an automobile, it is engaged with the nut 5. The connecting arm 9 is configured to swing with respect to the axial movement of the nut 5, and the U-shaped recess 9 c is formed in the yoke portion 15 of the connecting arm 9. A wide contact range between the projections 11 of the nut 9c and the nut 5 can be secured, and the swing angle of the connecting arm 9 can be set large.

  Furthermore, since the convex part 11 of the nut 5 is engaged with the concave part 9c of the connection arm 9 via the guide roller 16 which consists of a rolling bearing, the contact part changes constantly instead of a fixed range. Accordingly, it is possible to provide an electric actuator that can suppress wear of the engaging portion and can perform a smooth swinging motion as compared with the conventional art.

  FIG. 3B shows a modification of the guide roller 16. This guide roller 22 basically differs from that described above only in the configuration of the outer peripheral surface of the outer ring 17, and other parts and parts having the same parts or parts having the same functions are denoted by the same reference numerals and duplicated. Description is omitted.

  The guide roller 22 is formed of a deep groove ball bearing, and an outer ring 17 having an outer rolling surface 17a formed on the inner periphery, and an inner ring 18 having an inner rolling surface 18a opposed to the outer rolling surface 17a formed on the inner periphery. A plurality of balls 20 accommodated between the rolling surfaces 17a and 18a by a cage 19 so as to be freely rollable, and shield plates 21 and 21 attached to both ends of the outer ring 17 are provided. Here, the elastic member 23 made of synthetic rubber is integrally joined by vulcanization bonding from the end surface of the outer ring 17 to the outer peripheral surface. As a result, even if an impact load is generated on the guide roller 22, the elastic member 23 relaxes it to improve durability, and the friction coefficient of the outer peripheral surface that becomes a contact portion with the recess of the connecting arm increases, and the positive Thus, the guide roller 22 can be rolled and the wear of the engaging portion can be further suppressed.

  FIG. 4 shows a modified example of the guide roller 16 described above. The guide roller 24 is composed of a rolling bearing formed of a needle roller bearing, and includes an outer ring 25 made of a steel plate press and a plurality of needle rollers 27 accommodated in the outer ring 25 by a cage 26 so as to be freely rollable. It consists of a so-called shell-type needle roller bearing. Here, the outer peripheral surface of the outer ring 25 is subjected to a phosphate film treatment. This surface treatment is a chemical conversion treatment in which a phosphate film is chemically formed on the surface of a metal using a phosphate solution such as iron phosphate, zinc phosphate, manganese phosphate, and so-called Parkerizing and Parker treatment. It is said. By forming a surface treatment having such a high friction coefficient on the outer peripheral surface of the outer ring 25, rusting is prevented and durability is improved, and the friction coefficient of the outer peripheral surface serving as a contact portion with the recess of the connecting arm is reduced. As a result, the guide roller 24 can be actively rolled and moved, and wear of the engaging portion can be further suppressed.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Of course, the scope of the present invention is indicated by the description of the scope of claims, and further, the equivalent meanings described in the scope of claims and all modifications within the scope of the scope of the present invention are included. Including.

  The electric actuator according to the present invention can be applied as an electric actuator used in a drive unit of a variable valve mechanism or an automatic control type manual transmission of a vehicle such as an automobile.

DESCRIPTION OF SYMBOLS 1 Electric actuator 2 Housing 2a Bearing hole 2b Insertion hole 3 Electric motor 3a Main shaft 4 Screw shaft 4a, 5a Screw groove 4b Serration 5 Nut 5b Flat surface 6 Ball 7 Ball screw 8 Rod shaft 8a, 8b Connecting part 9 Connecting arm 9a Base end Part 9b Tip part 9c Recess 10 Rolling bearing 11 Protruding part 12 Bearing 13 Fixing screw 14 Screw hole 15 Yoke parts 16, 22, 24 Guide rollers 17, 25 Outer ring 17a Outer rolling surface 18 Inner ring 18a Inner rolling surface 19, 26 Cage 20 Ball 21 Shield plate 27 Needle roller 50 Ball screw nut 51 Arm 52 Output shaft 53 First arm 54 Second arm 55 Convex 56 Metal 57 Pin 58 Plate 59 Screw 60 Nut 61 Connecting member 61a Main body 61b Arm 61c Spherical surface Seat 61d, 60a Spherical surface 62 Spherical body 63 Screw shaft 63a Thread groove 64 Tube 65 Bearing C Coupling D Sphere diameter H Housing Ha Cylindrical hole R Spherical radius S Drive shaft

Claims (8)

An electric motor attached to the housing;
A screw shaft that is coupled to the main shaft of the electric motor and has a helical thread groove formed on the outer periphery thereof, is supported so as to be rotatable with respect to the housing and not movable in the axial direction, and a number of balls are mounted on the screw shaft. A ball screw made of a nut that is extrapolated through and has a helical thread groove corresponding to the thread groove of the screw shaft formed on the inner periphery, and is supported so as to be non-rotatable and movable in the axial direction;
A connecting arm having a yoke portion with a tip portion formed in a bifurcated shape,
In the electric actuator in which the connecting arm is engaged with the nut, and the rotational movement of the electric motor is converted into the axial movement or the swinging movement of the connecting arm via the nut.
A pair of cylindrical convex portions are arranged opposite to each other on the outer peripheral surface of the nut, a guide roller comprising a rolling bearing is fitted to the convex portions, and a U-shaped recess is formed in the yoke portion of the connecting arm. The electric actuator is characterized in that these recesses and the projections of the nut are engaged via the guide roller.   A pair of flat surfaces are formed to face the outer peripheral surface of the nut, the convex portions are formed on the flat surfaces, and the connecting arm in a state where the yoke portion of the connecting arm sandwiches the flat surface of the nut. The electric actuator according to claim 1, wherein the nut is attached to the nut.   2. The electric actuator according to claim 1, wherein the screw shaft and the main shaft of the electric motor are coupled so as to be able to transmit torque coaxially and detachably in an axial direction via serrations.   The electric actuator according to claim 1, wherein an elastic member made of synthetic rubber is integrally joined to an outer peripheral surface of the outer ring of the guide roller.   The electric actuator according to claim 1, wherein a surface treatment having a high friction coefficient is applied to an outer peripheral surface of an outer ring of the guide roller.   The electric actuator according to claim 5, wherein the surface treatment is a phosphate film treatment.   The electric actuator according to claim 1, wherein the guide roller is formed of a sealed type rolling bearing. The electric actuator according to claim 1, wherein the guide roller is configured by a rolling bearing including a needle roller bearing.

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