JP2018044636A - Electric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric actuator capable of enhancing power transmission efficiency from a motor to an output side of the actuator, by assembling the motor and a motion conversion mechanism in a state of performing centering with accuracy.SOLUTION: An electric actuator 1 includes: a motor 7; a motion conversion mechanism 11 configured to convert rotary motion generated by driving of the motor 7 into linear motion; a case 12 storing the motion conversion mechanism 11; and a connection part 10 connecting the motor 7 to the case 12. The motion conversion mechanism 11 has a rotary part 30 configured to rotate with rotary motion from the motor 7, and a linear motion part 31 configured to perform linear motion with rotary motion from the rotary part 30. The rotary part 30 is supported by the bearings 13, 14. The bearings 13, 14 are attached only to the case 12, and the bearings 13, 14 and an end part 24 of the connection part 10 on the base side are attached to an inner peripheral surface 37 of the case 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric actuator.

  In recent years, electrification for the purpose of labor saving and low fuel consumption of vehicles has been progressing. For example, a system that operates motors such as automatic transmissions, brakes, steering, etc. with the power of a motor has been developed and put on the market. Has been. As an actuator used for such an application, an electric actuator using a ball screw mechanism that converts a rotational motion generated by driving a motor into a linear motion is known.

  In addition, among actuators using a ball screw mechanism, when considering a predetermined output with a motor having as small an output as possible, a configuration in which the motor and the ball screw mechanism are arranged in series is preferable (for example, Patent Document 1). See).

  By the way, when considering applying this type of actuator to mass production applications such as in-vehicle use, it is indispensable to examine production costs. That is, in order to reduce the production cost, it is important to select and use an inexpensive motor such as a motor with a brush. When the above-described actuator is configured using a motor with a brush in this way, a waterproof and dustproof motor cover and a motor cover for the above case are separated from a case that covers a motion conversion mechanism such as a ball screw mechanism. Therefore, a member for positioning and fixing is required.

  Here, for example, Patent Document 2 proposes that a positioning plate for positioning the motor with respect to the ball screw mechanism is fitted to the outer ring of the ball screw support bearing. More specifically, the positioning plate is fixed to a housing body that serves as both a motor case and a ball screw case, and is fitted with a motor by a so-called inlay, and the inlay hole for the motor and the center lines of the screws are parallel to each other. The shaft is fitted with a bearing for a screw shaft through an inlay hole for the shaft. At this time, the screw shaft bearing (outer ring) is in a state of being fitted and fixed to the positioning plate and the bearing spacer interposed between the positioning plate and the housing body.

JP 2009-156415 A Japanese Patent No. 5218817

  When the motor and the bearing are attached to the housing body as described in Patent Document 2, the positioning of the motor is performed with reference to the positioning plate, whereas the screw shaft bearing that supports the screw shaft is between the positioning plate and the bearing. It is positioned and fixed by the seat. Therefore, the mounting position of the bearing is affected not only by the positioning plate position accuracy and shape accuracy but also by the spacer shape accuracy and the spacer assembly accuracy. In such a structure in which the bearing is positioned and fixed across a plurality of members, the center line of the rotation shaft of the motor and the center line of the screw shaft should be accurately centered even if a positioning plate is used. Is difficult.

  In view of the above circumstances, in this specification, the power transmission efficiency between the motor and the output side of the actuator is achieved by assembling the motor and the motion conversion mechanism in a state where the centering is performed accurately. It is a technical problem to be solved to provide an electric actuator capable of increasing the resistance.

  The solution to the above problem is achieved by the electric actuator according to the present invention. That is, the actuator includes a motor, a motion conversion mechanism that converts the rotational motion generated by driving the motor into a linear motion, a case that houses the motion conversion mechanism, and a connecting portion that connects the motor to the case, and converts the motion. The mechanism is an electric actuator having a rotating part that rotates by receiving a rotating motion from a motor and a linear motion part that receives a rotating motion from the rotating part and performs a linear motion, and the rotating part is supported by a bearing, The bearing is characterized in that it is attached only to the case, and that both the bearing and the end of the connecting portion on the case side are attached to the inner peripheral surface of the case.

  Thus, in the present invention, the bearing that supports the rotating portion of the motion conversion mechanism is attached only to the case that houses the motion conversion mechanism, and the case and the end of the connecting member on the case side are both connected to the inner periphery of the case. It was attached to the surface. Thus, by attaching the bearing to only one case, the positioning accuracy can be easily increased as compared to the case where the bearing is attached across a plurality of members. In addition, by attaching both the bearing and the case end of the connecting part to the inner peripheral surface of the case, both the connecting member and the bearing are positioned in the case with reference to the inner peripheral surface of the case as a common mounting surface. Can be fixed. Thereby, centering can be accurately performed between the rotation center of the rotating portion supported by the bearing and the center line of the rotating shaft of the motor connected to the connecting portion. Therefore, it becomes possible to efficiently transmit the driving force transmitted from the motor to the rotating portion to the linear motion portion with as little loss as possible.

  In the electric actuator according to the present invention, the inner peripheral surface of the case is an equal-diameter cylindrical surface having a constant inner diameter, and the case-side end portion of the bearing and the connecting portion is fitted to the equal-diameter cylindrical surface. It may be.

  As described above, the inner peripheral surface of the case, which is a common mounting surface for the bearing and the connecting member, is an equal-diameter cylindrical surface having a constant inner diameter dimension. Compared with the case of using the mounting surface, the shape accuracy (processing accuracy) of the mounting surface can be easily increased. Therefore, centering between the rotation center of the rotating part supported by the bearing and the rotation axis center line of the motor connected to the connecting part can be performed with high accuracy and at low cost.

  In the electric actuator according to the present invention, the motion conversion mechanism and the motor are arranged in series, and the connecting portion has a smaller diameter than the case side end portion on the side opposite to the case side end portion in the axial direction. It may have a motor fitting part which fits with a motor. In this case, in the electric actuator according to the present invention, the center line of the case side end portion may coincide with the center line of the motor fitting portion.

  By configuring the actuator in this way, the distance between the motor and the motion conversion mechanism is reduced to make the entire actuator compact, and more direct power transmission is possible. Even in this case, as described above, the connecting portion and the bearing can be positioned and fixed on the basis of the common mounting surface provided on the inner periphery of the case, so that the rotation center of the rotating portion supported by the bearing is connected to the connecting portion. The centering can be accurately performed between the center line of the rotating shaft of the motor connected to the unit. Therefore, it becomes possible to efficiently transmit the driving force transmitted from the motor to the rotating portion to the linear motion portion with as little loss as possible. In particular, when the connecting portion (case side end portion) and the motor fitting portion are provided on both sides in the axial direction of the connecting portion, the center line of the case side end portion and the motor are relatively easily Since the center line of the fitting portion can be made coincident, it is also preferable in terms of processing accuracy and processing efficiency.

  In the electric actuator according to the present invention, a planetary gear unit as a speed reduction mechanism is disposed between the motion conversion mechanism and the motor, and the ring gear constituting the planetary gear unit is integrated with the inner periphery of the connecting portion. It may be formed.

  By integrally forming the ring gear constituting the planetary gear unit on the inner periphery of the connecting portion, the number of parts can be reduced while improving the centering accuracy described above. Therefore, it is suitable for both accuracy and cost.

  As described above, according to the electric actuator according to the present invention, the assembly is performed in a state where the motor and the motion conversion mechanism are accurately centered, so that the motor can reach the output side of the actuator. It becomes possible to improve the power transmission efficiency.

It is a longitudinal section of the electric actuator concerning a first embodiment of the present invention. It is an external appearance perspective view of the electric actuator shown in FIG. FIG. 2 is a partially exploded perspective view of the electric actuator shown in FIG. 1. FIG. 2 is a cross-sectional view of the electric actuator when a cross section taken along line AA in FIG. FIG. 2 is a partially exploded perspective view of the electric actuator shown in FIG. 1. FIG. 3 is a cross-sectional view of the electric actuator when a cross section taken along line B-B in FIG. It is a disassembled perspective view of the ball screw shaft in the state where the permanent magnet was attached. It is a longitudinal cross-sectional view of the electric actuator which concerns on 2nd embodiment of this invention. It is a partial exploded perspective view of the electric actuator shown in FIG. It is a longitudinal cross-sectional view of the electric actuator which concerns on 3rd embodiment of this invention. It is a partially exploded perspective view of the electric actuator shown in FIG. FIG. 11 is a partially exploded perspective view of the electric actuator with the perspective direction changed.

  Hereinafter, based on FIGS. 1-7, 1st embodiment of this invention is described. Note that in each drawing, substantially the same elements are denoted by the same reference numerals as much as possible, and the detailed description thereof will be omitted once described. The same applies to the description after the second embodiment of the present invention to be described later.

  FIG. 1 shows a longitudinal sectional view of an electric actuator according to a first embodiment of the present invention. 2 is an external perspective view of the electric actuator shown in FIG. 1, and FIG. 3 is a partially exploded perspective view of the electric actuator shown in FIG.

  As shown in FIG. 1, the electric actuator 1 according to this embodiment includes a drive unit 2 that generates a driving force, a motion conversion mechanism unit 3 that converts a rotational motion from the drive unit 2 into a linear motion, and a drive unit 2. A driving force transmission unit 4 that transmits a driving force to the motion conversion mechanism unit 3, a motion conversion mechanism support unit 5 that supports the motion conversion mechanism unit 3, and an operation unit 6 that outputs the motion of the motion conversion mechanism unit 3. Prepare. In the present embodiment, the drive unit 2 has a drive force generation motor (drive motor 7), and the drive force transmission unit 4 transmits the drive force received from the drive unit 2 to the motion conversion mechanism unit 3. It has a speed reduction mechanism 8 as a force transmission mechanism.

  In addition, each element of the electric actuator 1 described above has a plurality of cases constituting the appearance of the electric actuator 1 (see FIG. 2). Specifically, the drive unit 2 has a motor cover 9 as a motor case that houses the drive motor 7, and the drive force transmission unit 4 is a reduction mechanism unit 8 (more precisely, a part of the reduction mechanism unit 8). Has a speed reduction mechanism case 10. In addition, the motion conversion mechanism unit 3 includes a ball screw case 12 that houses a ball screw mechanism 11 as a motion conversion mechanism. The ball screw case 12 also serves as a case for housing the bearings 13 and 14 constituting the motion conversion mechanism support portion 5. In the present embodiment, the drive unit 2, the drive force transmission unit 4, and the motion conversion mechanism unit 3 are configured to be connected and separated together with the case. Hereinafter, details of each element constituting the electric actuator 1 will be described.

  The drive unit 2 mainly includes a drive motor 7 such as a DC motor, and a motor cover 9 that houses the drive motor 7. The motor cover 9 includes a bottomed cylindrical cover main body 15 that covers the periphery of the driving motor 7, and a flange portion 16 that protrudes radially outward from one end opening side (left side in FIG. 1) of the cover main body 15. Have

  The drive motor 7 is inserted into the cover main body 15 from one end opening side. At this time, the inner peripheral surface 15 a of the cover main body 15 is tapered from one end opening side to the back side, and when the driving motor 7 is inserted into the cover main body 15, The rear side in the insertion direction is configured to come into contact with the inner peripheral surface 15a of the cover body 15 while avoiding contact with the surface. On the other hand, a motor fitting portion 17 to be described later is fitted with a predetermined fitting (for example, inlay) on the projection portion 7a on the output side (left side in FIG. 1) of the driving motor 7, The drive motor 7 is supported by the cover main body 15 and the motor fitting portion 17 in a state of being accommodated in the cover main body 15. In the present embodiment, an O-ring 18 is interposed between the drive motor 7 and the inner bottom surface 15b of the cover main body 15, and the output shaft of the drive motor 7 is suppressed while suppressing the backlash of the motor in the axial direction. The outflow of grease etc. from 7b is prevented.

  As shown in FIG. 4, the drive motor 7 is attached with a pair of terminals 19, 19 for connecting the drive motor 7 to a power source. One end portion 19a of each terminal 19 is connected by being inserted into the terminal insertion groove 7c of the drive motor 7, and the other end portion 19b is crimped by crimping an electric wire (not shown) so as to be electrically connected to an external power source. ing. The pair of terminals 19 and 19 are held by a terminal holder 20 that can be fitted to the outer periphery of the drive motor 7 (see FIGS. 3 and 4), thereby preventing the drive motor 7 from being detached. Yes. A grommet 21 is fitted in a hole 15c provided in the bottom of the cover body 15 (see FIGS. 1 and 3), and is illustrated through a pair of holes 21a and 21a provided in the grommet 21. It is possible to pull out the wires that are not used.

  As shown in FIG. 1, the driving force transmission unit 4 mainly includes a speed reduction mechanism unit 8 as a driving force transmission mechanism and a speed reduction mechanism case 10 that houses the speed reduction mechanism unit 8. The speed reduction mechanism unit 8 includes a planetary gear speed reduction mechanism 22 including a plurality of gears, for example. The detailed configuration of the planetary gear speed reduction mechanism 22 will be described later.

  The speed reduction mechanism case 10 corresponds to a connecting portion according to the present invention. For example, as shown in FIG. 3, the case body 23 has a generally cylindrical shape, and one end side in the axial direction from the case body 23 (in FIG. 1, A screw case fitting portion 24 that protrudes to the left) and engages with the ball screw case 12, and protrudes radially inward from the other axial end side (right side in FIG. 1) of the case body 23. It has integrally the motor fitting part 17 which fits the protrusion part 7a and predetermined | prescribed fitting (for example, inlay). When the above configuration is adopted, the screw case fitting portion 24 of the speed reduction mechanism case 10 is accommodated in the ball screw case 12 by attaching the speed reduction mechanism case 10 to the ball screw case 12 as shown in FIG. Further, by attaching the motor cover 9 to the speed reduction mechanism case 10, a part of the case main body 23 of the speed reduction mechanism case 10 and the motor fitting portion 17 are accommodated in the motor cover 9. As described above, when the screw case fitting portion 24 and the motor fitting portion 17 are integrally provided in the speed reduction mechanism case 10, the drive motor 7, the speed reduction mechanism portion 8, and a motion conversion mechanism (ball screw mechanism described later). 11) and the center line of the screw case fitting portion 24 and the center line of the fitting hole 17a of the motor fitting portion 17 are preferably coincident with each other. By fixing the protrusion 7a of the driving motor 7 to the motor fitting portion 17, the center line of the fitting hole 17a of the motor fitting portion 17 and the rotation center line X of the driving motor 7 (see FIG. 1) Can be made to coincide with each other with high accuracy, and the rotation center line X of the drive motor 7 and the rotation center of the ball screw nut 30 are made to coincide with each other by a common mounting surface (equal diameter cylindrical surface 37) to be described later. This is because it becomes possible.

  Further, in this embodiment, the speed reduction mechanism case 10 integrally has a flange portion 25 extending radially outward from the case body 23. This flange portion 25, the flange portion 16 of the motor cover 9, and a later-described portion. The flange portions 26 of the ball screw case 12 are connected to each other by, for example, bolts 27 (see FIG. 3) in a state where they are overlapped with each other. At this time, O-rings 28 and 29 (see FIGS. 1 and 3) may be interposed between the flange portions 16, 25 and 26.

  As shown in FIG. 1, the motion conversion mechanism unit 3 includes a ball screw mechanism 11 as a motion conversion mechanism and a ball screw case 12 that accommodates the ball screw mechanism 11 in the present embodiment. Of these, the ball screw mechanism 11 includes a ball screw nut 30 as a rotating part, a ball screw shaft 31 as a linearly movable part (that is, a linearly acting part), a large number of balls 32, and a top 33 as a circulating member. It consists of Helical grooves 30a and 31a are formed on the inner peripheral surface of the ball screw nut 30 and the outer peripheral surface of the ball screw shaft 31, respectively. Balls 32 are filled between the spiral grooves 30a and 31a, and a top 33 is incorporated, whereby two rows of balls 32 circulate.

  The ball screw nut 30 receives the driving force generated by the driving motor 7 and rotates in either the forward or reverse direction. On the other hand, the rotation of the ball screw shaft 31 is restricted by a sliding surface 34 (a left end portion of the ball screw case 12 in FIG. 1) as a rotation preventing mechanism described later. For this reason, when the ball screw nut 30 rotates, the ball 32 circulates along both the spiral grooves 30a and 31a and the top 33, and the ball screw shaft 31 moves linearly (or reciprocating linearly) in one direction along the axial direction. Exercise). FIG. 1 shows a state in which the ball screw shaft 31 is disposed at an initial position which is most retracted to the right side of the drawing. The ball screw shaft 31 is arranged so as to be parallel to the output shaft 7 b of the driving motor 7, and so that the center lines of the shafts 31 and 7 b coincide with each other, and through the driving force transmission unit 4. 7 is converted into a linear motion in the axial direction parallel to the output shaft 7b by the ball screw shaft 31. In this case, the forward end portion (left end portion in FIG. 1) of the ball screw shaft 31 functions as an operation portion (actuator head) 6 that operates an operation target.

  The ball screw case 12 has a generally cylindrical shape (see FIG. 2), and is located on the case main body 35 and one end side in the axial direction of the case main body 35 (on the left side in FIG. 1). And a flange portion 26 located on the other end side in the axial direction (right side in FIG. 1) of the case main body 35, for example. Further, between the ball screw case 12 and the ball screw nut 30 configured as described above, two bearings 13 and 14 are disposed apart from each other in the center line direction of the case main body 35 (left and right direction in FIG. 1). The ball screw nut 30 is rotatably supported by these two bearings 13 and 14. In the present embodiment, the two bearings 13 and 14 are both rolling bearings, and both the outer rings 13a and 14a are provided on a constant-diameter cylindrical surface 37 having a constant inner diameter dimension provided on the inner periphery of the case body 35. It is attached by fitting (see FIG. 1).

  Further, the screw case fitting portion 24 protruding to one end side in the axial direction (left side in FIG. 1) of the speed reduction mechanism case 10 is attached to the equal-diameter cylindrical surface 37 with a predetermined fit (for example, inlay). . Thereby, both the screw case fitting portion 24 and the two bearings 13 and 14 are fixed to the ball screw case 12 in a state of being centered on the basis of the equal-diameter cylindrical surface 37. The screw case fitting portion 24 is automatically attached by attaching the speed reduction mechanism case 10 to the ball screw case 12 by, for example, bolt fastening between the flange portions 25 and 26 (see FIG. 3).

  In the present embodiment, the ball screw case 12 integrally has a metallic cylindrical member 38. In this case, the equal-diameter cylindrical surface 37 is configured by the inner peripheral surface of the tubular member 38. Therefore, the inner peripheral surface of the cylindrical member 38 is in a state where the cylindricity and the like are finished with high accuracy. Further, the cylindrical member 38 integrally has an end surface support portion 39 that protrudes inward in the radial direction from one axial end side (left side in FIG. 1) of the equal-diameter cylindrical surface 37. The inner side surface 39a of the end surface support portion 39 is exposed in the inner space of the ball screw case 12, and the inner side surface 39a is one end side in the axial direction of the cylindrical member 38 of the two bearings 13 and 14 (FIG. 1). In other words, it is in contact with the bearing 13 located on the left side). Therefore, the bearing 13 is positioned in the axial direction with reference to the inner side surface 39a, and the bearing 13 is supported in the axial direction by the end surface support portion 39.

  A ball screw shaft 31 as a linear motion portion is inserted into the small diameter portion 36 (see FIG. 1). A sliding surface 34 on which the ball screw shaft 31 can slide is provided on the inner periphery of the small diameter portion 36. In the present embodiment, a sliding bearing 40 made of sintered metal is provided on the inner periphery of the tip of the small diameter portion 36, and a sliding surface 34 is formed on the inner periphery of the sliding bearing 40. The sliding bearing 40 may be impregnated with a lubricant such as grease or lubricating oil so that the lubricant is continuously supplied to the sliding surface 34.

  In the present embodiment, the sliding surface 34 is provided with a detent mechanism for the ball screw shaft 31. Specifically, as shown in FIGS. 1 and 5, the sliding surface 34 is composed of one flat surface 34 a forming a part in the circumferential direction and a partial cylinder connected to the flat surface 34 a and forming the remainder in the circumferential direction. It is comprised by the surface 34b. As shown in FIGS. 1 and 5, at least the sliding area 31 b that slides with the sliding surface 34 of the outer peripheral surface of the ball screw shaft 31 is a flat surface corresponding to the flat surface 34 a constituting the sliding surface 34. It is comprised by the surface part 31b1 and the partial cylindrical surface part 31b2 corresponding to the partial cylindrical surface 34b. In this case, the dimensions of the surfaces 31b1 and 34a are such that the flat surface portion 31b1 of the ball screw shaft 31 is in contact (engaged) with the flat surface 34a at least at its maximum outer diameter portion (boundary portion with the partial cylindrical surface portion 31b2). Is set. As a result, the flat surface 34 a plays a role of regulating the rotation around the center line of the ball screw shaft 31. 1 and 5, a member denoted by reference numeral 41 is a retaining ring, and is attached to a predetermined position in the axial direction of the ball screw shaft 31 to thereby have a member having a sliding surface 34 (here, a sliding bearing 40) and an end surface. By abutting each other, it plays a role of regulating the movement of the ball screw shaft 31 in the axial direction.

  As described above, when the ball screw case 12 includes the cylindrical member 38 and the slide bearing 40, the ball screw case 12 is, for example, a resin molded product using both the cylindrical member 38 and the slide bearing 40 as insert parts. It is possible. At this time, for the purpose of accurately positioning the cylindrical member 38 in the axial direction, for example, as shown in FIGS. 1 and 5, a positioning hole 12 a of the cylindrical member 38 may be provided in the resin portion of the ball screw case 12. Good.

  Arbitrary products can be used for the bearings 13 and 14, for example, a rolling bearing such as a deep groove ball bearing can be suitably used. In this embodiment, as shown in FIGS. 1 and 5, the ball screw nut 30 has a large-diameter portion 30b at an intermediate position in the axial direction. Two bearings (rolling bearings) 13 and 14 are attached. In the illustrated example, a bearing 13 having both an outer ring 13a and an inner ring 13b is used as the bearing 13 on the side closer to the operation unit 6 (the side far from the driving motor 7), and the side farther from the operation unit 6 (for driving) As the bearing 14 on the side close to the motor 7, a bearing 14 having only an outer ring 14 a and no inner ring is used. However, the bearing 14 is not limited to this, and a bearing 14 having both an outer ring and an inner ring is used. May be.

  Further, in the present embodiment, the bearing 13 on the side close to the operation portion 6 is axially moved by the end surface support portion 39 of the tubular member 38 via the plate-like elastic member 42 as shown in FIGS. It is supported. As this plate-like elastic member 42, for example, a wave washer can be used. When the inside of the ball screw case 12 is configured as described above, the screw case fitting portion 24 of the speed reduction mechanism case 10 is fitted to the equal-diameter cylindrical surface 37 of the ball screw case 12 as shown in FIG. In a state where the speed reduction mechanism case 10 is attached to the ball screw case 12, the screw case fitting portion 24 is in a state where the bearing 14 on the side close to the drive motor 7 is pressed in the axial direction. 1 and 5 is a spacer washer, which serves to prevent interference between the plate-like elastic member 42 and the inner ring 13b of the bearing 13.

  A boot 44 for preventing entry of foreign matter into the ball screw case 12 is attached between the small diameter portion 36 and the ball screw shaft 31 (see FIG. 1). The boot 44 is made of resin or rubber, and includes a large-diameter end portion 44a and a small-diameter end portion 44b, and a bellows portion 44c that extends and contracts in the axial direction by connecting the large-diameter end portion 44a and the small-diameter end portion 44b. Yes. The large-diameter end portion 44a is fastened and fixed to the attachment portion of the outer peripheral surface of the small-diameter portion 36 by the first boot band 45, and the small-diameter end portion 44b is fixed to the attachment portion of the outer peripheral surface of the ball screw shaft 31 by the second boot band 46. Tightened and fixed. In addition, a boot cover 47 that covers the boot 44 is disposed around the boot 44 (see FIGS. 1 and 5). The boot cover 47 is attached to, for example, the ball screw case 12 adjacent in the axial direction. In addition, although illustration is abbreviate | omitted, you may provide a vent hole in the ball screw case 12, for example in order to relieve the rapid pressure fluctuation of the internal space of the boot 44 when the boot 44 expands and contracts.

  Here, the planetary gear reduction mechanism 22 will be described with reference to FIGS. 1, 3, and 6. 3 is an exploded perspective view of the planetary gear speed reduction mechanism 22, and FIG. 6 is a cross-sectional view of the cross section taken along the line BB in FIG.

  The planetary gear reduction mechanism 22 includes a ring gear 48, a sun gear 49, a plurality of planetary gears 50, a planetary gear carrier 51, and a planetary gear holder 52. The ring gear 48 may be manufactured separately from the ball screw case 12, for example, and then fixed to the ball screw case 12. However, when the cylindrical member 38 or the slide bearing 40 is used as an insert part as described above, For example, a metal ring gear 48 may be integrally formed with the ball screw case 12 as an insert part, like the cylindrical member 38 or the like. Of course, if there is no problem in terms of rigidity, the ring gear 48 may be formed of resin as a part of the resin portion of the ball screw case 12.

  As shown in FIG. 6, a sun gear 49 is disposed in the center of the ring gear 48, and the output shaft 7b of the drive motor 7 is connected to the sun gear 49 by press fitting (see FIG. 1). Each planetary gear 50 is disposed between the ring gear 48 and the sun gear 49 so as to mesh with the ring gear 48 and the sun gear 49 (see FIG. 6). Each planetary gear 50 is rotatably supported by a planetary gear carrier 51 and a planetary gear holder 52. The planetary gear carrier 51 has a cylindrical portion 51a on the outermost diameter side (see FIG. 3), and this cylindrical portion 51a is connected to the outer peripheral surface of the ball screw nut 30 by press fitting or the like (see FIG. 1). reference). As a result, the driving force from the driving motor 7 can be transmitted as a rotational force to the ball screw nut 30 via the planetary gear carrier 51.

  In the planetary gear speed reduction mechanism 22 configured as described above, when the drive motor 7 is driven to rotate, the sun gear 49 connected to the output shaft 7b of the drive motor 7 rotates, and accordingly, each planetary gear 50 rotates. While revolving along the ring gear 48. The planetary gear carrier 51 is rotated by the revolving motion of the planetary gear 50. As a result, the rotational motion of the drive motor 7 is decelerated and transmitted to the ball screw nut 30 and the rotational torque as the driving force is increased and transmitted to the ball screw nut 30. As described above, since the driving force is transmitted through the planetary gear speed reduction mechanism 22, the driving force transmitted to the ball screw shaft 31 and, consequently, the output of the ball screw shaft 31 can be greatly obtained. It is possible to reduce the size of the motor 7 (change to a motor with a small output).

  The electric actuator 1 is equipped with a position detection device for detecting the position of the operation unit 6 provided on the ball screw shaft 31 in the linear movement direction (stroke direction). As shown in FIGS. 1 and 7, the position detection device is provided at a predetermined position of a permanent magnet 53 (see FIG. 1) as a sensor target provided at a predetermined position of the ball screw shaft 31 and a boot cover 47. And a magnetic sensor 54 as a position detection sensor.

  Among these, as shown in FIGS. 1 and 5, the magnetic sensor 54 is formed integrally with the sensor substrate 55, and the sensor substrate 55 is fixed to the sensor case 57 by an appropriate connecting member 56. Then, the sensor assembly 58 formed by attaching the sensor substrate 55 to the sensor case 57 is attached to a sensor attachment portion 47a provided at a predetermined position in the circumferential direction of the boot cover 47 by fitting or the like, so that the magnetic sensor 54 is booted. The cover 47 is installed at a predetermined position in the circumferential direction and faces the permanent magnet 53 via the boot 44 and the boot cover 47 (see FIG. 1). In this case, the magnetic sensor 54 is covered with the boot cover 47 and the sensor case 57 (see FIG. 1).

  Arbitrary types can be used as the magnetic sensor 54. Among them, a type of magnetic sensor capable of detecting the direction and magnitude of the magnetic field using the Hall effect, such as Hall IC and linear Hall IC, can be preferably used.

  The sensor case 57 and the boot cover 47 that cover the periphery of the magnetic sensor 54 are preferably formed of a nonmagnetic material, for example, a resin.

  On the other hand, the permanent magnet 53 serving as a sensor target is disposed on the ball screw shaft 31 serving as a movable portion. Specifically, as shown in FIG. 1, a permanent magnet 53 is disposed between the operation unit 6 and the spiral groove 31 a of the ball screw shaft 31.

  FIG. 7 shows an exploded perspective view of the ball screw shaft 31 in a state where the sensor target unit 59 including the permanent magnet 53 is attached. As shown in FIG. 7, a notch 31c is formed at a predetermined position in the axial direction of the ball screw shaft 31, and a sensor target unit 59 is attached to the notch 31c.

  On the other hand, as shown in FIG. 7, the sensor target unit 59 includes a permanent magnet 53, and a first magnet holder 60 and a second magnet holder 61 that hold the permanent magnet 53. The first magnet holder 60 is provided with a pair or a plurality of pairs (two pairs in the illustrated example) of fitting claws 60 a that can be fitted into the notch 31 c of the ball screw shaft 31. In addition, a housing portion 60b capable of housing the permanent magnet 53 is provided on the side opposite to the protruding side of the fitting claw 60a.

  The fitting claw 60a has a shape that substantially follows the outer peripheral surface of the ball screw shaft 31 to be attached (see FIG. 5). For example, by pressing the first magnet holder 60 from the flat surface portion 31b1 side, Each pair of fitting claws 60a is deformed (elastically deformed) in a direction away from each other, and then restored toward a shape in close contact with the surface of the notch 31c.

  The shape of the accommodating portion 60b is set according to the permanent magnet 53 to be accommodated. In the illustrated example, as shown in FIG. 7, a cylindrical housing portion 60 b is formed in the first magnet holder 60 in accordance with the columnar permanent magnet 53. The accommodating portion 60b is opened only at one end in the axial direction thereof, and the permanent magnet 53 is inserted from the opening 60b1 side, and the second magnet holder 61 is cut out at the notch 31c so as to close the opening 60b1. The permanent magnet 53 can be clamped by the first and second magnet holders 60 and 61 at a predetermined axial position. Therefore, by attaching the sensor target unit 59 having the above configuration to the notch 31c, the permanent magnet 53 is fixed at a predetermined axial position on the ball screw shaft 31 (see FIG. 1).

  The material of the magnet holders 60 and 61 having the above configuration is basically arbitrary. For example, when the influence of the permanent magnet 53 on the magnetic field formed around it is considered, the magnet holders 60 and 61 are preferably made of a nonmagnetic material, and the elastic deformability of the fitting claw 60a is taken into account. It is good to use resin.

  Further, the permanent magnet 53 has a direction perpendicular to its both end faces 53a and 53b (see FIG. 1) as the magnetization direction. That is, it is in a state of being magnetized so that one end face 53a is an N pole and the other end face 53b is an S pole. Thereby, the magnetization direction of the permanent magnet 53 in the state attached to the ball screw shaft 31 is made to correspond with the linear motion direction of the ball screw shaft 31 (refer FIG. 1).

  In the position detection apparatus configured as described above, when the ball screw shaft 31 moves back and forth, the position of the permanent magnet 53 with respect to the magnetic sensor 54 changes, and accordingly, the magnetic field at the location where the magnetic sensor 54 is disposed also changes. Therefore, the change in the magnetic field (for example, the direction and strength of the magnetic flux density) is detected by the magnetic sensor 54, so that the position of the permanent magnet 53 in the stroke direction and the stroke of the operation unit 6 provided on one end side of the ball screw shaft 31. The direction position can be acquired.

  The configuration and operation of the electric actuator 1 of the present embodiment are as described above. Hereinafter, the effect of this invention is demonstrated regarding the electric actuator 1 of this embodiment.

  As described above, in the electric actuator 1 of the present embodiment, the bearings 13 and 14 that support the ball screw nut 30 as the rotating portion of the ball screw mechanism 11 are attached only to the ball screw case 12 that accommodates the ball screw mechanism 11. At the same time, both the bearings 13 and 14 and the end of the reduction mechanism case 10 serving as a connecting portion on the side of the ball screw case 12, that is, the screw case fitting portion 24 are connected to the inner peripheral surface of the ball screw case 12 (here, an equal-diameter cylinder). Attached to the surface 37). Thus, by attaching the bearings 13 and 14 only to one case (ball screw case 12), the positioning accuracy can be easily increased as compared to the case where the bearings are attached across a plurality of members. Further, by attaching both the bearings 13 and 14 and the screw case fitting portion 24 of the speed reduction mechanism case 10 to the inner peripheral surface of the ball screw case 12, both the speed reduction mechanism case 10 and the bearings 13 and 14 as connecting portions are provided. Can be positioned and fixed to the ball screw case 12 with reference to the inner peripheral surface of the ball screw case 12 serving as a common mounting surface. As a result, centering is accurately performed between the rotation center of the ball screw nut 30 supported by the bearings 13 and 14 and the rotation center line X of the output shaft 7b of the drive motor 7 connected to the speed reduction mechanism case 10. It can be carried out. Therefore, it is possible to efficiently transmit the driving force transmitted from the driving motor 7 to the ball screw nut 30 to the ball screw shaft 31 without losing as much as possible.

  In particular, in the present embodiment, the ball screw mechanism 11 and the drive motor 7 are arranged in series, and the speed reduction mechanism case 10 as a connecting portion is on the opposite side in the axial direction from the screw case fitting portion 24. A motor fitting portion 17 that is smaller in diameter than the screw case fitting portion 24 and is fitted to the driving motor 7 is provided. By configuring the electric actuator 1 in this way, the distance between the drive motor 7 and the ball screw mechanism 11 is reduced to make the entire electric actuator 1 compact, and more direct power transmission is possible. Further, in the case of adopting this configuration, the center line of the screw case fitting portion 24 and the center line of the motor fitting portion 17 coincide with each other relatively easily (more specifically, the rotation of the output shaft 7b of the drive motor 7). Therefore, it is also preferable in terms of processing accuracy and processing efficiency.

  Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 8 shows a longitudinal sectional view of the electric actuator 101 according to the second embodiment of the present invention. FIG. 9 is a partially exploded perspective view of the electric actuator 101 shown in FIG. As shown in these drawings, the electric actuator 101 according to the present embodiment has a configuration in which the speed reduction mechanism unit 8 is omitted. Compared with the electric actuator 1 shown in FIG. 1, instead of omitting the speed reduction mechanism portion 8 (planetary gear speed reduction mechanism 22), a coupling 62 as a connecting portion is provided, and the driving motor 7 is connected by this coupling 62. And the ball screw nut 30 are directly connected. In this case, the coupling 62 has a flat surface 62a on the outer periphery, and is fitted and fixed to the inner peripheral surface 30c (see FIG. 8) on the other axial end side of the ball screw nut 30, for example, by fitting. This enables connection with the ball screw nut 30 and torque transmission.

  On the other hand, the configuration other than the above is the same as that of the electric actuator 1 according to the first embodiment. That is, in this embodiment, the speed reduction mechanism case 10 according to the first embodiment is used as it is as a driving force transmission mechanism case for housing the coupling 62. Therefore, as shown in FIG. 9, the ring gear 48 constituting the planetary gear speed reduction mechanism 22 remains, but the members housed in the speed reduction mechanism case 10 are one of the coupling 62 and the output shaft 7 b of the drive motor 7. And only a part of the ball screw nut 30, there is no possibility of interference with the ring gear 48. Therefore, the speed reduction mechanism case 10 according to the first embodiment can be used as it is as a driving force transmission mechanism case. As described above, in the electric actuator 1 shown in FIG. 1 and the electric actuator 101 shown in FIG. 8, only a part of the parts (the speed reduction mechanism unit 8 and the coupling 62) is replaced, and many other parts are common parts. Can be configured. Thereby, since the kind of parts which should be prepared can be reduced, the series-ization of the electric actuator mentioned above is realizable at low cost.

  In this embodiment as well, since the connection structure between the ball screw case 12 and the drive motor 7 is the same as that in the first embodiment, the rotation center of the ball screw nut 30 supported by the bearings 13 and 14 and the deceleration are reduced. The centering can be accurately performed with the rotation center line X of the output shaft 7b of the driving motor 7 connected to the mechanism case 10. Therefore, it is possible to efficiently transmit the driving force transmitted from the driving motor 7 to the ball screw nut 30 to the ball screw shaft 31 without losing as much as possible.

  Hereinafter, a third embodiment of the present invention will be described with reference to FIGS.

  FIG. 10 shows a longitudinal sectional view of the electric actuator 201 according to the third embodiment of the present invention. 11 is a partially exploded perspective view of the electric actuator 201 shown in FIG. 10, and FIG. 12 is an exploded perspective view of a main part of the electric actuator 201 whose perspective direction is changed from that in FIG. As shown in these drawings, the electric actuator 201 according to the present embodiment has a different type of drive motor compared to the electric actuator 1 shown in FIG. 1, specifically, the first and second embodiments. The drive motor 63 has a larger output than the drive motor 7 and the power supply structure of the drive motor 63 is changed.

  Specifically, as shown in FIG. 10, the driving force transmission mechanism case 64 is similar to the speed reduction mechanism case 10 shown in FIG. 1. The case main body 23, the screw case fitting portion 24, the motor fitting portion 17, And the flange portion 25 are integrally provided. On the other hand, a pair of bus bars 65 for connecting the driving motor 63 to the power source is attached (built in) to the driving force transmission mechanism case 64. As shown in FIG. 12, one end portion 65a of each bus bar 65 is connected to a terminal 63a protruding in the axial direction from the driving motor 63 by, for example, close contact with caulking or the like, and the other end portion 65b is connected to the case. It is exposed to the outside from the main body 23 (flange portion 25) (see FIGS. 10 to 12). Thereby, electrical connection between the drive motor 63 and the power source via the bus bar 65 is enabled. In this case, since the grommet 21 (see FIG. 3) is not necessary, no hole is opened (closed) in the bottom of the motor cover 66.

  On the other hand, the configuration other than the above is the same as that of the electric actuator 101 according to the second embodiment. That is, in this embodiment, the motion conversion mechanism unit 3 (ball screw mechanism 11 and ball screw case 12), the motion conversion mechanism support unit 5, the operation unit 6, and the drive motor 63 and the ball according to the second embodiment. A connecting portion (coupling 62) for connecting to the screw nut 30 is used as it is. As described above, in the electric actuator 101 shown in FIG. 8 and the electric actuator 201 shown in FIG. 10, only a part of the components (the speed reduction mechanism case 10 and the driving force transmission mechanism case 64) is mainly replaced. Parts can be composed of common parts. Thereby, since the kind of parts which should be prepared can be reduced, the series-ization of the electric actuator mentioned above is realizable at low cost. In addition, as a specific example of the development of various products accompanying the series of electric actuators 1, 101, 201, an electric mechanism using a conventional solenoid such as an EGR valve or a transmission control valve for an automobile including a two-wheeled vehicle is illustrated. be able to.

  In the above-described embodiment (third embodiment), the driving force transmission mechanism case 64 having the bus bar 65 and the structure without the speed reduction mechanism portion 8 are exemplified. It is also possible to configure an electric actuator having both 64 and the speed reduction mechanism 8.

  The motion conversion mechanism unit 3 is not limited to the ball screw mechanism 11 but may be a sliding screw device. However, the ball screw mechanism 11 is more preferable from the viewpoint of reducing the rotational torque and reducing the size of the drive motor 7. Moreover, in the above-mentioned embodiment, although the structure which used the deep groove ball bearing was illustrated as the bearings 13 and 14 which support the motion conversion mechanism part 3, it is not restricted to this, For example, you may use an angular ball bearing. Furthermore, depending on conditions, the bearings 13 and 14 are not limited to rolling bearings, and other types of bearings such as sliding bearings may be used. In the above embodiment, the ball screw nut 30 is supported by the two bearings 13 and 14. Of course, the number of the bearings 13 may be one or three or more.

DESCRIPTION OF SYMBOLS 1,101,201 Electric actuator 2 Drive part 3 Motion conversion mechanism part 4 Drive force transmission part 5 Motion conversion mechanism support part 6 Operation part 7 Driving motor 7a Projection part 7b Output shaft 7c Terminal insertion groove 8 Reduction mechanism part 9 Motor cover 10 Deceleration mechanism case (connection part)
11 Ball screw mechanism 12 Ball screw case 12a Positioning holes 13, 14 Bearings 13a, 14a Outer ring 13b Inner ring 15 Cover body 15a Inner peripheral surface 15b Inner bottom surface 15c Holes 16, 25, 26 Flange part 17 Motor fitting part 17a Fitting hole 18 , 28, 29 O-ring 19 Terminal 19a One end 19b Other end 20 Terminal holder 21 Grommet 21a Hole 22 Planetary gear reduction mechanism 23 Case body 24 Screw case fitting portion 27 Bolt 30 Ball screw nut 30a Spiral groove 30b Large diameter portion 30c Inner peripheral surface 31 Ball screw shaft 31a Spiral groove 31b Sliding region 31b1 Flat surface portion 31b2 Partial cylindrical surface portion 31c Notched portion 32 Ball 33 Top 34 Sliding surface 34a Flat surface 34b Partial cylindrical surface 35 Case body 36 Small diameter portion 37, etc. Diameter cylindrical surface 38 Cylindrical member 39 End surface support part 9a Inner surface 40 Sliding bearing 41 Retaining ring 42 Plate-like elastic member 43 Space washer 44 Boot 44a Large diameter end 44b Small diameter end 44c Bellows 45 First boot band 46 Second boot band 47 Boot cover 47a Sensor mounting Part 48 ring gear 49 sun gear 50 planetary gear 51 planetary gear carrier 51a cylindrical part 52 planetary gear holder 53 permanent magnets 53a, 53b end face 54 magnetic sensor 55 sensor board 56 connecting member 57 sensor case 58 sensor assembly 59 sensor target unit 60 first magnet holder 60a fitting claw 60b accommodation portion 60b1 opening 61 second magnet holder 62 coupling 62a flat surface 63 driving motor 63a terminal 64 driving force transmission mechanism case 65 bus bar 65a one end portion 65b other end portion 66 motor cover

Claims (5)

A motion conversion mechanism that converts a rotational motion generated by driving the motor into a linear motion; a case that accommodates the motion conversion mechanism; and a connecting portion that connects the motor to the case. The mechanism is an electric actuator having a rotating part that rotates in response to a rotational motion from the motor and a linear motion part that receives the rotational motion from the rotating part and performs the linear motion.
The rotating part is supported by a bearing, the bearing is attached only to the case, and both the bearing and the end of the connecting part on the case side are attached to the inner peripheral surface of the case. An electric actuator characterized by that.   2. The case according to claim 1, wherein the inner peripheral surface of the case is an equal-diameter cylindrical surface having a constant inner diameter, and the case-side end portion of the bearing and the connecting portion is fitted to the equal-diameter cylindrical surface. Electric actuator. The motion conversion mechanism and the motor are arranged in series,
3. The electric motor according to claim 1, wherein the connecting portion includes a motor fitting portion that is fitted to the motor with a smaller diameter than the case side end portion on a side opposite to the case side end portion in the axial direction. Actuator.   The electric actuator according to claim 3, wherein a center line of the case side end portion and a center line of the motor fitting portion coincide with each other. A planetary gear unit as a speed reduction mechanism is disposed between the motion conversion mechanism and the motor,
The electric actuator according to claim 3 or 4, wherein a ring gear constituting the planetary gear unit is integrally formed on an inner periphery of the connecting portion.

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