JP6713314B2 - Electric actuator - Google Patents

Description

The present invention relates to an electric actuator.

In recent years, the electrification for the purpose of labor saving and low fuel consumption of vehicles has been progressing. For example, a system for operating an automatic transmission, a brake, a steering wheel, etc. of an automobile by the power of an electric motor such as a motor has been developed and marketed. Has been thrown into. As an actuator used for such an application, an electric actuator using a ball screw mechanism that converts a rotational motion generated by driving an electric motor into a linear motion is known (see Patent Document 1).

Further, in this type of actuator, it is important to control the stroke amount or the position in the stroke direction of the operation unit (that is, the actuator head) that outputs the linear motion described above. Therefore, as a means for detecting the stroke amount or the position in the stroke direction, for example, the rotation angle of the motor is detected (see Patent Document 2), and the stroke amount or the stroke direction of the actuator head is detected based on the detected rotation angle. It has been proposed to calculate the position of

Japanese Patent No. 5243018 JP, 2005-187483, A

By the way, in the electric actuator as described above, since the actuator head is generally provided at one end side in the longitudinal direction of the movable portion (that is, the stroke portion) that performs linear movement, the movable portion (mainly the motion conversion mechanism) is Easy to be exposed to the outside. Therefore, it is necessary to prevent the entry of foreign matter into the inside of the movable part by covering the space between the movable part and its surroundings.

On the other hand, in the method of calculating the stroke amount of the actuator head based on the rotation angle of the motor as in the conventional art, the amount of stroke between the actual stroke amount and the calculated stroke amount is inevitable due to the influence of backlash of various components related to motion conversion. Shift occurs. In order to solve this problem, it is conceivable to adopt a method of directly detecting that the actuator head or the movable portion provided with the actuator head has reached a predetermined position by using a laser sensor or a contact sensor, for example. With these methods, it is necessary to sense the exposed portion of the head or the movable portion with a laser or a contactor. In this case, there is a problem that it is difficult to cover the space between the movable part and its surroundings, and it is difficult to secure the sealing property of the movable part.

In view of the above circumstances, the present invention is a technical problem to be solved to provide an electric actuator capable of highly accurately detecting the stroke amount or the position in the stroke direction while ensuring the sealing property of the movable portion. And

The solution to the above problem is achieved by an electric actuator according to the present invention. That is, this actuator includes a motor and a motion conversion mechanism that converts a rotational motion generated by driving the motor into a linear motion in a direction parallel to the output shaft of the motor, and the motion conversion mechanism is disposed parallel to the output shaft. In an electric actuator having a movable part which is linearly moved, a resin or rubber boot is arranged between the movable part and a fixed system around the movable part, and a part of the movable part covered with the boot is provided. It is characterized in that a magnet is arranged and a magnetic sensor for detecting the position of the magnet in the linear movement direction is arranged around the boot. The term "fixed system" as used herein means an element or a group of elements that do not change the positional relationship with respect to an external element on which the electric actuator is mounted or fixed, among the elements that constitute the electric actuator.

As described above, in the present invention, the boot is arranged between the movable portion and the fixed system around the movable portion, so that the boot can prevent foreign matter from entering the motion conversion mechanism. Further, by disposing the magnet in the portion of the movable portion covered by the boot and disposing the magnetic sensor around the boot, the boot exists between the sensor and the sensor target, but the boot is made of resin or Since it is made of rubber, it does not interfere with the detection of the magnetic field by the magnetic sensor. Therefore, it is possible to accurately detect the position of the movable portion in the linear movement direction while sealing the inside of the movement conversion mechanism with the boot. Further, by disposing the magnet in the portion covered by the boot as in the present invention, it is possible to prevent deterioration and damage due to exposure of the magnet to the outside air as much as possible, so that it is possible to achieve high accuracy over a long period of time. It becomes possible to exert the position detection function.

In the electric actuator according to the present invention, the magnet is attached to the movable portion via the magnet holder that holds the magnet, and the magnetic sensor is attached to the boot cover that covers the boot. Both the boot cover and the boot cover may be made of a non-magnetic material.

With this configuration, the magnetic field generated around at least the magnet is less likely to be disturbed by the magnet holder. Further, the possibility that the magnetic field to be detected by the magnetic sensor is disturbed by the influence of the boot cover is reduced. Therefore, the change in the magnetic field (for example, magnetic flux density) can be detected more accurately by the magnetic sensor, and the detection accuracy can be further improved or stabilized.

Further, in the electric actuator according to the present invention, the magnetic sensor may be a Hall IC. The Hall IC here includes a linear Hall IC that linearly outputs a voltage.

As the magnetic sensor, any sensor can be used as long as it can detect the magnetic field generated around the magnet and can detect the position of the magnet in the linear movement direction. Among them, the Hall IC is particularly compact. Since the change in the magnetic field can be detected accurately despite the configuration, improvement in position detection accuracy can be expected.

Further, in the electric actuator according to the present invention, the magnetizing direction of the magnet in the state of being attached to the movable portion may be the same as the linear movement direction of the movable portion.

By making the magnetizing direction of the magnet coincide with the linear movement direction of the movable portion in this manner, more magnetic lines of force are generated around the movable portion than on both ends in the stroke direction of the movable portion. Here, since the magnetic sensor is disposed on the boot cover that covers the boot, the magnetic sensor is disposed around the movable portion in relation to the movable portion. As a result, the change in the direction of the magnetic field detected by the magnetic sensor is likely to appear significantly. Therefore, the detectability of the magnetic field change by the magnetic sensor can be improved, and the position of the magnet in the linear movement direction can be detected with higher accuracy.

Further, the electric actuator according to the present invention may be one in which a magnetic shield plate is disposed at least between the magnetic sensor and the periphery of the motor.

Since the motor has a magnet inside, a predetermined magnetic field is formed around the motor. On the other hand, the electric actuator according to the present invention has a configuration in which the output shaft of the motor and the movable portion serving as the output portion of the motion conversion mechanism are arranged in parallel. When this is done, the distance between the motor and the movable part is inevitably reduced. Since the magnetic sensor is arranged around the movable part, the distance between the magnetic sensor and the motor is also reduced. In this case, the magnetic field formed around the motor affects the magnetic field that should be originally detected by the magnetic sensor, which may make accurate position detection difficult. Therefore, in the present invention, the magnetic shield plate is arranged around the motor which is one of the magnetic field generation sources. Further, the magnetic shield plate is arranged at least between the motor and the magnetic sensor. By providing the magnetic shielding plate in this way, the magnetic field generated by the motor is blocked, so that only the magnetic field that should be originally detected (the magnetic field generated by the magnet that constitutes the magnetic detection device together with the magnetic sensor) is accurately detected. Then, it becomes possible to detect the position of the movable portion with high accuracy.

Further, in this case, in the electric actuator according to the present invention, the magnetic shielding plate may have a cylindrical shape and may be arranged between the motor and the motor case that houses the motor.

By configuring the magnetic shield plate as described above, the motor is in a state of being covered by the magnetic shield plate over the entire circumference thereof. In this case, since the magnetic shield plate can form a closed magnetic circuit together with the motor as a kind of yoke, the magnetic field (specifically, magnetic flux) generated by the magnet in the motor leaks to the outside of the motor. Can be prevented as much as possible. Therefore, the influence of the magnetic field exerted on the magnetic sensor can be more surely eliminated, and more accurate position detection can be achieved.

As described above, according to the present invention, it is possible to provide an electric actuator capable of easily and highly accurately detecting the stroke amount or the position in the stroke direction while enhancing the sealing property of the movable portion.

It is a longitudinal cross-sectional view of the electric actuator which concerns on one Embodiment of this invention. It is an external appearance perspective view of an electric actuator. It is an exploded perspective view of an electric actuator. It is the figure which looked at a motor case from the opening side. It is the cross-sectional view which looked at the cross section along the AA line of FIG. 1 from the direction of arrow A. It is an exploded perspective view of a reduction mechanism part. It is an exploded perspective view of a shaft case and a lock mechanism part attached to this. It is the cross-sectional view which looked at the cross section along the BB line of FIG. 1 from the direction of arrow B. It is the cross-sectional view which looked at the cross section along the CC line of FIG. 1 from the direction of arrow C. It is the cross-sectional view which looked at the cross section along the DD line of FIG. 1 from the direction of arrow D. It is sectional drawing which looked at the cross section along the EE line of FIG. 10 from the direction of arrow E. It is a perspective view of the ball screw shaft in the state where the magnet was attached. It is a perspective view of a ball screw shaft. It is a (a) perspective view of the sensor target which consists of a magnet and a magnet holder, and a (b) front view. It is sectional drawing of FIG. 11 in the state which the ball screw shaft advanced. It is a control block diagram of an electric actuator. It is a longitudinal cross-sectional view of the electric actuator which concerns on the modification of FIG. It is a cross-sectional view of the electric actuator which concerns on other embodiment of this invention. It is a principal part sectional view of the electric actuator which concerns on other embodiment of this invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. In each of the drawings for explaining the present invention, components such as members and components having the same function or shape are denoted by the same reference numerals as far as possible to distinguish them from each other. Omit it.

1 is a longitudinal sectional view showing an assembled state of an electric actuator according to an embodiment of the present invention, FIG. 2 is an external perspective view showing the assembled state of the electric actuator, and FIG. 3 is an exploded perspective view of the electric actuator. Is.

As shown in FIG. 1, the electric actuator 1 according to the present embodiment includes a drive unit 2 that generates a drive 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, an operation unit 6 that outputs the motion of the motion conversion mechanism unit 3, and a motion. And a lock mechanism section 7 for preventing the conversion mechanism section from being driven. The drive unit 2 is composed of a motor unit 8 and a speed reduction mechanism unit 9.

Each part of the electric actuator 1 has a case, and the components are housed in each case. Specifically, the motor unit 8 has a motor case 11 that houses a driving force generating motor (driving motor 10 ), and the reduction mechanism unit 9 has a reduction gear case 17 that houses a reduction gear mechanism 16. Further, the driving force transmission unit 4 has a transmission gear case 29 that accommodates the transmission gear mechanism 28, and the motion conversion mechanism support unit 5 has a bearing case 41 that accommodates the support bearing 40. In the present embodiment, the motor unit 8 and the speed reduction mechanism unit 9, the speed reduction mechanism unit 9 and the driving force transmission unit 4, and the driving force transmission unit 4 and the motion conversion mechanism support unit 5 are configured to be connectable and separable together with the case. .. Further, the shaft case 50 is configured to be connectable and separable from the bearing case 41. Hereinafter, a detailed configuration of each part of the electric actuator 1 will be described.

The motor unit 8 mainly includes a drive motor (for example, a DC motor) 10 for driving the motion conversion mechanism unit 3, and a motor case 11 that houses the drive motor 10. The motor case 11 has a bottomed cylindrical case body 12 in which the drive motor 10 is housed, and a protrusion 13 protruding outward from a bottom portion 12 a of the case body 12. The protrusion 13 is formed with a hole 13a communicating with the internal space of the case body 12. The hole 13a is sealed by a resin sealing member 14 that covers the outer surface of the protrusion 13.

The drive motor 10 is in a state of being inserted inside from the opening 12d of the case body 12. At this time, the end surface of the drive motor 10 on the rear side in the insertion direction is in contact with the bottom portion 12 a of the case body 12. Further, a fitting hole 12c is formed in the center of the bottom portion 12a, and a projection 10b on the rear side in the insertion direction of the drive motor 10 is fitted into the fitting hole 12c to drive the projection 10b. This makes it possible to avoid a situation in which the rear end (the left end in FIG. 1) of the output shaft 10a of the motor 10 interferes with the bottom 12a of the motor case 11. Furthermore, the inner peripheral surface of the peripheral wall portion 12b of the case body 12 is tapered in diameter from the opening 12d side toward the bottom 12a side, and when the drive motor 10 is inserted into the case body 12, the drive motor 10 is driven. The outer peripheral surface on the rear side in the insertion direction of the motor 10 is configured to contact the inner peripheral surface of the peripheral wall portion 12b. As described above, the driving motor 10 is supported by being in contact with the inner peripheral surface of the case body 12 and being fitted in the fitting hole 12c while being housed in the case body 12.

Further, as shown in FIG. 4 in which the motor case 11 is viewed from the opening 12d side, a pair of bus bars 15 for connecting the drive motor 10 to a power source is attached to the case body 12. One end 15a of each bus bar 15 is connected to the motor terminal 10c by caulking, and the other end 15b is exposed from the case body 12 to the outside (see FIGS. 2 and 3). The other end 15b of the bus bar 15 exposed to the outside is connected to the power source.

As shown in FIG. 1, the reduction gear mechanism 9 mainly includes a reduction gear mechanism 16 that decelerates and outputs the driving force of the drive motor 10, and a reduction gear case 17 that houses the reduction gear mechanism 16. .. The reduction gear mechanism 16 includes a planetary gear reduction mechanism 18 including a plurality of gears and the like. The detailed configuration of the planetary gear reduction mechanism 18 will be described later.

The reduction gear case 17 is provided with an accommodation recess 17a for accommodating the planetary gear reduction mechanism 18 from the side opposite to the drive motor 10. A motor adapter 19 can be attached to the reduction gear case 17. The motor adapter 19 is a tubular member, and the protrusion 10d on the output side (right side in FIG. 1) of the drive motor 10 is inserted into the inner peripheral surface of the motor adapter 19 so that the drive motor 10 is fitted (internal Has been fitted). A fitting hole 17b into which the motor adapter 19 is fitted is formed in the reduction gear case 17, and the reduction gear case 17 is inserted into the fitting hole 17b by inserting the motor adapter 19 from the drive motor 10 side. A motor adapter 19 is attached.

The reduction gear case 17 is configured to be fittable with the motor case 11 and also with a transmission gear case 29, which will be described later, disposed on the side opposite to the motor case 11. In the reduction gear case 17, a portion arranged on the motor case 11 side is fitted inside the opening 12d side of the motor case 11, and a portion arranged on the transmission gear case 29 side is fitted outside the transmission gear case 29. .. In this case, the reduction gear case 17 is fastened to the drive motor 10 together with the motor adapter 19 by the bolts 21 (see FIGS. 3 and 6) while being fitted to the motor case 11. In the state where the reduction gear case 17 and the motor case 11 are fitted to the drive motor 10 side of the reduction gear case 17, the motor terminal 10c protruding from the drive motor 10 and the state in which the motor terminal 10c is crimped. A recess 17c is formed to avoid interference between the one end 15a of the bus bar 15 and the reduction gear case 17. A mounting groove 17d for mounting the O-ring 20 is formed on the outer peripheral surface of the reduction gear case 17 having a small diameter outer peripheral surface that fits with the inner peripheral surface of the motor case 11.

The motion conversion mechanism section 3 is composed of a ball screw 22 in this embodiment. The ball screw 22 is composed of a ball screw nut 23 as a rotating body, a ball screw shaft 24 as a movable portion (that is, a stroke portion) that linearly moves, a large number of balls 25, and a top 26 as a circulating member. There is. Spiral grooves 23a and 24a are formed on the inner peripheral surface of the ball screw nut 23 and the outer peripheral surface of the ball screw shaft 24, respectively. A ball 25 is filled between the spiral grooves 23a and 24a, and a top 26 is incorporated therein, whereby two rows of balls 25 are circulated.

The ball screw nut 23 receives a driving force generated by the driving motor 10 and rotates in either forward or reverse directions. On the other hand, the rotation of the ball screw shaft 24 is regulated by a pin 27 as a rotation regulating member provided at the rear end portion (right end portion in FIG. 1). Therefore, when the ball screw nut 23 rotates, the ball 25 circulates along the spiral grooves 23a and 24a and the top 26, and the ball screw shaft 24 makes a linear motion along the axial direction. FIG. 1 shows a state in which the ball screw shaft 24 is arranged at an initial position in which the ball screw shaft 24 is most retracted to the right side of the drawing. The ball screw shaft 24 is arranged in parallel with the output shaft 10 a of the drive motor 10, and the rotational movement transmitted from the drive motor 10 via the drive force transmission unit 4 is output by the ball screw shaft 24 to the output shaft 10 a. Is converted into a linear motion in the axial direction parallel to. In this case, the forward end portion of the ball screw shaft 24 in the forward direction (the left end portion in FIG. 1) functions as the operation unit (actuator head) 6 that operates the operation target.

The driving force transmission unit 4 mainly includes a transmission gear mechanism 28 that transmits a driving force and a rotational movement from the driving motor 10 of the driving unit 2 to the ball screw 22 that constitutes the motion conversion mechanism unit 3, and a transmission gear mechanism 28. It is composed of a transmission gear case 29 to be housed. The transmission gear mechanism 28 includes a drive gear 30 on the drive side, a driven gear 31 on the driven side that meshes with the drive gear 30, and a gear boss 32.

A gear boss 32 is fitted into the center of rotation of the drive gear 30 by press fitting or the like. The drive gear 30 is rotatably supported by two rolling bearings 33 and 34 mounted on the transmission gear case 29 and a bearing case 41, which will be described later, via the gear boss 32. On the other hand, the driven gear 31 is fixed by being fitted to the outer peripheral surface of the ball screw nut 23 by press fitting or the like. When the driving force from the driving motor 10 is transmitted to the drive gear 30 via the planetary gear reduction mechanism 18, the driving force is transmitted to the driven gear 31 by the engagement of the drive gear 30 and the driven gear 31. As a result, the driven gear 31 and the ball screw nut 23 rotate integrally, and the ball screw shaft 24 moves forward or backward along the longitudinal direction.

The transmission gear case 29 has a housing recess 29a in which the drive gear 30 and the driven gear 31 are housed. Further, the transmission gear case 29 is formed with an insertion hole 29b for inserting the gear boss 32, and one rolling bearing 33 supporting the gear boss 32 is mounted on the inner peripheral surface of the insertion hole 29b. Are formed. Further, the transmission gear case 29 has an annular protrusion 29 d that fits with the inner peripheral surface of the reduction gear case 17. A mounting groove 29e for mounting the O-ring 35 is formed on the outer peripheral surface (fitting surface) of the annular projection 29d. In addition, a groove-shaped fitting recess 29f that fits into the bearing case 41 is formed on the surface of the transmission gear case 29 on the bearing case 41 side.

Further, the transmission gear case 29 has a cylindrical portion 29g protruding toward the tip end side (the left side in FIG. 1) of the ball screw shaft 24. The cylindrical portion 29g is a portion arranged to cover the ball screw shaft 24 in a state where the driven gear 31 is housed in the transmission gear case 29 and the ball screw 22 is assembled to the driven gear 31. A boot 36 is attached between the cylindrical portion 29g and the ball screw shaft 24 to prevent foreign matter from entering the transmission gear case 29. In this case, the cylindrical portion 29g constitutes a fixed system of the electric actuator 1. The boot 36 is made of resin or rubber, and is composed of a large-diameter end portion 36a, a small-diameter end portion 36b, and a bellows portion 36c that connects these and expands and contracts in the axial direction. The large-diameter end portion 36a is fastened and fixed to the mounting portion on the outer peripheral surface of the cylindrical portion 29g by the boot band 37, and the small-diameter end portion 36b is fastened and fixed to the mounting portion on the outer peripheral surface of the ball screw shaft 24 by the boot band 38. The cylindrical portion 29g is provided with a vent hole 29h for ventilating inside and outside when the boot 36 expands and contracts. The motor case 11 is integrally provided with a boot cover 39 arranged around the boot 36. In this case, the boot cover 39 constitutes a fixed system of the electric actuator 1.

The motion conversion mechanism support portion 5 mainly includes a support bearing 40 that supports the ball screw 22 that is the motion conversion mechanism portion 3, and a bearing case 41 that houses the support bearing 40. In the present embodiment, the support bearing 40 is composed of an outer ring 42, an inner ring 43, and back-aligned double-row angular contact ball bearings whose main components are double-row balls 44 interposed therebetween.

The support bearing 40 is housed in a sleeve 45 formed integrally with the bearing case 41, and is fixed by a retaining ring 46 mounted on the inner peripheral surface of the sleeve 45. The fixed position of the support bearing 40 is press-fitted to the outer peripheral surface of the ball screw nut 23 on the rear end side (right side in FIG. 1) of the ball screw shaft 24 with respect to the driven gear 31. The support bearing 40 and the driven gear 31, which are fixed to the outer peripheral surface of the ball screw nut 23, are axially controlled by the restriction protrusion 23b provided on the driven gear 31 side of the ball screw nut 23 and the restriction member 47 mounted on the support bearing 40 side. Movement is regulated. The regulation member 47 is composed of a pair of semi-circular members, and is mounted on the outer peripheral surface of the ball screw nut 23 in a state where these members are combined in an annular shape. Further, on the outer peripheral surface of the ball screw nut 23, a pressing collar 48 that holds the restricting member 47 and a retaining ring 49 that prevents the pressing collar 48 from falling off in the axial direction are mounted.

On the transmission gear case 29 side of the bearing case 41, a protrusion 41a that fits into the fitting recess 29f of the transmission gear case 29 is provided. Further, on the transmission gear case 29 side of the bearing case 41, a gear boss accommodating portion 41b for accommodating a part of the gear boss 32 protruding from the transmission gear case 29 in a state where the bearing case 41 is fitted with the transmission gear case 29 is provided. There is. A bearing mounting surface 41c for mounting the rolling bearing 34 that supports the gear boss 32 is formed on the inner peripheral surface of the gear boss accommodating portion 41b.

On the side opposite to the transmission gear case 29 side of the bearing case 41, a bottomed cylindrical shaft case 50 that accommodates the rear end side (the right end side in FIG. 1) of the ball screw shaft 24 is provided with a bolt 51 (see FIG. 3). (See) is configured so that it can be fastened. A mounting groove 50a for mounting the O-ring 52 is formed on the contact surface of the shaft case 50 with the bearing case 41. A guide groove 50b into which both ends of a pin 27 provided on the ball screw shaft 24 is inserted is formed on the inner peripheral surface of the shaft case 50 so as to extend in the axial direction. Guide collars 53 are rotatably attached to both ends of the pin 27, and when the ball screw shaft 24 moves back and forth in the axial direction, the guide collars 53 move while rotating along the guide grooves 50b.

As shown in FIG. 3, the motor case 11, the reduction gear case 17, the transmission gear case 29, and the bearing case 41 are provided on the outer periphery in the radial direction of each case with a bolt insertion hole 11a through which a bolt 54 for assembling and fastening them is inserted. , 17e, 29i, 41d are provided. Further, through holes 29j and 41e for mounting the assembled electric actuator 1 at the installation location are provided on the outer periphery of both the transmission gear case 29 and the bearing case 41 in the radial direction.

Here, the planetary gear reduction mechanism 18 will be described with reference to FIGS. 1, 5 and 6. 5 is a cross-sectional view of the cross section taken along the line AA of FIG. 1 as seen from the direction of arrow A, and FIG. 6 is an exploded perspective view of the planetary gear reduction mechanism 18.

The planetary gear reduction mechanism 18 includes a ring gear 55, a sun gear 56, a plurality of planetary gears 57, a planetary gear carrier 58 (see FIG. 1), and a planetary gear holder 59 (see FIG. 1). The ring gear 55 has a plurality of protrusions 55a protruding in the axial direction, and the accommodating recess 17a of the reduction gear case 17 is provided with the same number of engaging recesses 17f as the protrusions 55a (see FIG. 1). By incorporating the convex portion 55a of the ring gear 55 in the engagement concave portion 17f of the reduction gear case 17 in a phase-aligned manner, the ring gear 55 is housed in a state in which it is prevented from rotating with respect to the reduction gear case 17.

A sun gear 56 is arranged in the center of the ring gear 55, and the output shaft 10a of the drive motor 10 is press-fitted into the sun gear 56. Further, the planet gears 57 are arranged between the ring gear 55 and the sun gear 56 so as to mesh with the ring gear 55 and the sun gear 56. Each planet gear 57 is rotatably supported by a planet gear carrier 58 and a planet gear holder 59. The planetary gear carrier 58 has a cylindrical portion 58a at the center thereof, and the cylindrical portion 58a is press-fitted between the outer peripheral surface of the gear boss 32 and the inner peripheral surface of the rolling bearing 33 as described above (see FIG. 1). reference). An annular collar 75 is mounted between the inner peripheral surface of the other rolling bearing 34 and the outer peripheral surface of the gear boss 32.

In the planetary gear speed reduction mechanism 18 configured as described above, when the drive motor 10 is rotationally driven, the sun gear 56 connected to the output shaft 10a of the drive motor 10 rotates, and along with this, each planet gear 57 rotates. While revolving, it revolves along the ring gear 55. The planetary gear carrier 58 is rotated by the revolution movement of the planetary gear 57. As a result, the rotational movement of the drive motor 10 is decelerated and transmitted to the drive gear 30, and at the same time, the rotational torque as a driving force is transmitted to the drive gear 30 in an increased state. In this way, since the driving force is transmitted through the planetary gear speed reduction mechanism 18, the driving force transmitted to the ball screw shaft 24, and hence the output of the ball screw shaft 24, can be increased. It is possible to reduce the size of the motor 10.

Next, details of the lock mechanism portion 7 will be described based on FIGS. 1, 7, and 8. 7 is an exploded perspective view of the shaft case 50 and the lock mechanism portion 7 attached to the shaft case 50, and FIG. 8 is a cross-sectional view of a cross section taken along the line BB in FIG. ..

The lock mechanism unit 7 includes a lock member 60, a slide screw nut 61, a slide screw shaft 62, a lock member fixing plate 63, a lock motor (for example, a DC motor) 64 as a lock drive source, and a spring 65. The main configuration. The lock mechanism section 7 is assembled, for example, by the following procedure. First, the lock member 60 is fastened to the slide screw nut 61 with the bolt 84 (see FIG. 7) via the lock member fixing plate 63. Next, the lock motor 64 is housed in the holder 66 provided in the shaft case 50, and the slide screw shaft 62 is attached to the output shaft 64 a of the lock motor 64 protruding from the holder 66. Then, the spring 65 is arranged on the outer circumference of the slide screw shaft 62, and the slide screw nut 61 to which the lock member 60 is attached is screwed onto the slide screw shaft 62 to be mounted. In this way, the assembly of the lock mechanism section 7 is completed.

The holder portion 66 is formed in a cylindrical shape with a bottom, and a cap 67 is attached to the side opposite to the bottom portion 66a. With the locking motor 64 inserted into the holder 66 and the cap 67 attached, the locking motor 64 contacts the bottom 66 a of the holder 66 and the inner surface of the cap 67. Further, in this state, the protrusion 64b on the output side (left side in FIG. 1) of the locking motor 64 is fitted into the fitting hole 66c formed in the bottom portion 66a of the holder portion 66. Since the outer peripheral surface of the main body of the lock motor 64 and the inner peripheral surface of the peripheral wall portion 66b of the holder portion 66 are both formed in the same shape that is not cylindrical, the lock motor 64 is formed inside the peripheral wall portion 66b of the holder portion 66. By being inserted, the rotation of the lock motor 64 is restricted. In this way, the locking motor 64 is housed in the holder 66, and thus the locking motor 64 is held by the holder 66 and the entire locking mechanism 7 is held. Further, a hole 67a for inserting the cable 68 connected to the motor terminal 64d of the lock motor 64 is formed in the cap 67 (see FIG. 8). In the present embodiment, the holder portion 66 is integrally provided as a part of the shaft case 50, but of course, the holder portion 66 may be formed separately from the shaft case 50 and attached to the bearing case 41. But it doesn't matter.

Lock mechanism accommodating recesses 66d and 41f are formed in a portion of the shaft case 50 where the holder portion 66 is provided and in a portion of the bearing case 41 that faces the holder portion 66, respectively, and the lock mechanism accommodating recess portion 41f on the bearing case 41 side is penetrated. A hole 41g is formed. As shown in FIG. 1, in the state where the shaft case 50 is attached to the bearing case 41, the output shaft 64a of the locking motor 64 protruding from the holder 66 and the sliding screw shaft are provided in the lock mechanism housing recesses 66d and 41f. 62, the slide screw nut 61, the lock member fixing plate 63, the spring 65 and a part of the lock member 60 are accommodated, and the tip end side of the lock member 60 is inserted into the through hole 41g. Further, in the state where the shaft case 50 is attached to the bearing case 41, the spring 65 is axially compressed between the bottom portion 66 a of the holder portion 66 and the lock member fixing plate 63, and the lock member 60 is compressed by the compressed spring 65. Is always biased in the forward direction (left side in FIG. 1).

The drive gear 30 is arranged in the direction in which the lock member 60 moves forward, and the drive gear 30 is formed with an engagement hole 30a with which the tip of the lock member 60 can be engaged. As shown in FIG. 9, which is a cross-sectional view of the cross section taken along the line C-C of FIG. 1 as viewed from the direction of arrow C, the engagement holes 30 a are provided at a plurality of locations over the circumferential direction of the drive gear 30. There is. The rotation of the drive gear 30 is restricted by engaging the lock member 60 with one of the engagement holes 30a. Further, an inclined surface 30b may be formed at the entrance of each engagement hole 30a (see FIG. 9). By forming the engagement hole 30a in this way, the effect that the lock member 60 is smoothly inserted into the engagement hole 30a along the inclined surface 30b can be expected.

A lock sensor 69 for detecting a locked state is attached to the bearing case 41 (see FIG. 8). The lock sensor 69 is a contact-type sensor having a contactor 69a made of an elastic member such as a leaf spring, and when the lock member 60 moves forward and is engaged with the engagement hole 30a (when in a locked state). When the lock member 60 pushes the contact 69a, the lock state is detected.

The lock mechanism unit 7 having the above-described configuration performs the operation described below, for example. That is, when electric power is not supplied to the lock motor 64, the lock member 60 is held at the advanced position by the spring 65, and the tip end portion of the lock member 60 is engaged with the engagement hole 30 a of the drive gear 30. It is locked. From this state, when power is supplied to the drive motor 10 to start driving the ball screw shaft 24, power is also supplied to the lock motor 64, and the lock motor 64 moves the lock member 60 backward. Drive to. As a result, the sliding screw shaft 62 rotates, while the sliding screw nut 61 is restricted from rotating by the insertion of the flat end of the lock member 60 into the through hole 41g. The screw nut 61 retracts against the biasing force of the spring 65, and the lock member 60 also retracts integrally with this. As a result, the tip of the lock member 60 is disengaged from the engagement hole 30a of the drive gear 30, and the locked state is released. Thus, while the ball screw shaft 24 is being driven, the lock member 60 is held in the retracted position, and the drive gear 30 is held in the unlocked state.

After that, when the power supply to the drive motor 10 is cut off and the driving of the ball screw shaft 24 is stopped, the power supply to the lock motor 64 is also cut off. As a result, the driving force for keeping the lock member 60 retracted is not generated, so that the lock member 60 is pushed and moved in the forward direction by the spring 65. Then, the front end portion of the lock member 60 engages with the engagement hole 30a of the drive gear 30 to be in a locked state, and rotation of the drive gear 30 is restricted.

In this way, the rotation of the drive gear 30 is restricted by the lock member 60, so that the ball screw shaft 24 is held in a state where it does not move forward and backward. Thereby, even if an external force is input from the operation target side to the ball screw shaft 24 side, the position of the ball screw shaft 24 can be held at a predetermined position. The above configuration is particularly suitable when the electric actuator is applied to an application that requires position holding.

In the present embodiment, the locking member 64 is moved backward by driving the locking motor 64, but conversely, the locking motor 64 may be driven in order to move the locking member 60 forward. Further, by rotating the lock motor 64 in the forward and reverse directions, the lock member 60 can be moved forward and backward.

The electric actuator 1 is equipped with a position detection device for detecting the position of the operation portion 6 provided on the ball screw shaft 24 in the stroke direction. This position detecting device includes a permanent magnet 73 (see FIG. 1) as a sensor target provided on the ball screw shaft 24, a boot cover 39 covering the boot 36, and a stroke sensor for detecting the position of the permanent magnet 73 in the stroke direction. A magnetic sensor 70 is provided as a reference (see FIGS. 2 and 3).

Here, the magnetic sensor 70 is provided on the boot cover 39 formed integrally with the motor case 11. Specifically, as shown in FIG. 10, a portion of the motor case 11 in which the drive motor 10 is housed (case body 12) and a portion near the boot cover 39 are connected to each other toward the outside of the motor case 11. An open sensor case 76 is provided. A sensor base 71 having two magnetic sensors 70 attached thereto is fastened and fixed to the sensor case 76 with bolts 72 (see FIG. 3). As a result, the magnetic sensor 70 faces the permanent magnet 73 via the boot cover 39. To be precise, the magnetic sensor 70 is arranged on the outer side in the radial direction of the ball screw shaft 24 so that the detection surface 70a of the magnetic sensor 70 faces the permanent magnet 73 when viewed from the direction shown in FIG. There is. In this case, the magnetic sensor 70 is covered with the boot cover 39, the sensor case 76, and the sensor base 71.

Further, the magnetic sensor 70 is disposed at an intermediate position in the axial direction (stroke direction) of the boot cover 39 (see FIG. 11). At this time, in terms of the positional relationship with the permanent magnet 73, the magnetic sensor 70 is preferably arranged within the stroke range of the permanent magnet 73 attached to the ball screw shaft 24 (see FIGS. 11 and 15).

As the magnetic sensor 70, any type can be used, and among them, a magnetic sensor of a type capable of detecting the direction and magnitude of the magnetic field by utilizing the Hall effect, such as a Hall IC or a linear Hall IC, can be preferably used.

Further, the sensor base 71 (particularly the base plate 71a of the sensor base 71 that contacts the magnetic sensor 70) that covers the periphery of the magnetic sensor 70, the sensor case 76, and the boot cover 39 are all preferably made of a non-magnetic material. For example, it is formed of resin.

On the other hand, the permanent magnet 73 that serves as a sensor target is disposed on the ball screw shaft 24 that serves as a movable portion. In detail, as shown in FIG. 1, a permanent magnet 73 is arranged between the operation portion 6 and the spiral groove 24a of the ball screw shaft 24.

Further, when viewed from the positional relationship with the magnetic sensor 70, as shown in FIG. 11, the permanent magnet 73 is arranged in a portion of the outer peripheral surface of the ball screw shaft 24 covered by the boot 36. As a result, the boot 36 is always present between the magnetic sensor 70 and the permanent magnet 73.

FIG. 12 is a perspective view of the ball screw shaft 24 (ball screw shaft unit) with the sensor target including the permanent magnet 73 attached at a predetermined axial position. Further, FIG. 13 shows a perspective view of the ball screw shaft 24 alone. As shown in these figures, a notch 241 is formed at a predetermined axial position of the ball screw shaft 24, and a sensor target is attached to the notch 241. The shape of the cutout portion 241 is appropriately set according to the shape of the magnet holder 74 to be attached. In the illustrated example, a flat surface 241a obtained by cutting the ball screw shaft 24 along an imaginary plane passing through a position radially displaced from the center of the ball screw shaft 24 and a flat surface located on both axial sides of the flat surface 241a. The pair of axial end faces 241b, 241b, which have a shape rising from the surface 241a in the radial direction of the ball screw shaft 24, constitute a cutout portion 241.

FIG. 14 shows a perspective view (a) and a front view (b) of a sensor target including the permanent magnet 73, respectively. As shown in these drawings, the sensor target includes a permanent magnet 73 and a magnet holder 74 that holds the permanent magnet 73. The magnet holder 74 is provided with a pair or a plurality of pairs (four pairs in the illustrated example) of fitting claws 741 that can be fitted to the outer peripheral surface of the ball screw shaft 24, or the cutout portion 241 in the present embodiment. .. Further, a fitting recess 742 into which the permanent magnet 73 can be fitted is provided on the side opposite to the protruding side of the fitting claw 741.

The fitting claw 741 has a shape that follows the outer peripheral surface of the ball screw shaft 24 to be attached (see FIGS. 10 and 14), and for example, by pushing the magnet holder 74 from the notch 241 side, The fitting claws 741 of each pair are deformed (elastically deformed) in a direction in which they are separated from each other, and are restored to their original positions in a state of being in contact with the flat surface 241a of the cutout portion 241.

The fitting recess 742 is formed separately from the pair of side wall portions 743, the first sandwiching portion 744 integrally formed with the pair of side wall portions 743, and the pair of side wall portions 743 and the first sandwiching portion 744. And a second holding portion 745 capable of holding the permanent magnet 73 between the first holding portion 744 and the first holding portion 744. In this case, of the four sides of the substantially rectangular shape that surrounds the fitting recess 742, only one side in the axial direction is opened, and the permanent magnet 73 and the second side are opened from the side of the opening 746 (see FIG. 14A). The sandwiching portion 745 can be inserted toward the fitting recess 742.

Further, the pair of side wall portions 743 are shaped so as to approach each other toward the tip end side thereof (see FIG. 14B). Thereby, the movement of the permanent magnet 73 fitted in the fitting recess 742 to the outside in the radial direction (upper side in FIG. 14B) is restricted.

The material of the magnet holder 74 having the above-described configuration is basically arbitrary as long as it is possible to fit the ball screw shaft 24 with elastic deformation of one or a plurality of pairs of fitting claws 741. For example, in consideration of the influence of the permanent magnet 73 on the magnetic field formed around the permanent magnet 73, it is preferable that the permanent magnet 73 is formed of a non-magnetic material, and in consideration of the elastic deformability of the fitting claw 741, the resin is preferably formed. Good.

Further, the permanent magnet 73 has a magnetizing direction in a direction orthogonal to both end faces 73a and 73b. That is, the one end surface 73a is magnetized so that the N pole and the other end surface 73b become the S pole. As a result, the magnetizing direction of the permanent magnet 73 attached to the ball screw shaft 24 matches the linear movement direction of the ball screw shaft 24 (see FIG. 11).

In the position detecting device configured as described above, when the ball screw shaft 24 moves back and forth, the position of the permanent magnet 73 with respect to the magnetic sensor 70 changes (see FIGS. 11 and 15), and the magnetic sensor 70 moves accordingly. The magnetic field at the installation location also changes. Therefore, by detecting the change in the magnetic field (for example, the direction and strength of the magnetic flux density) by the magnetic sensor 70, the stroke direction position of the permanent magnet 73, and thus the stroke of the operation unit 6 provided on one end side of the ball screw shaft 24. The direction position can be obtained.

Next, feedback control using the magnetic sensor 70 will be described with reference to FIG.

As shown in FIG. 16, when the target value is sent to the control device 80, a control signal is sent from the controller 81 of the control device 80 to the drive motor 10. The target value is, for example, a stroke value calculated by the ECU based on the operation amount when the operation amount is input to the vehicle upper ECU.

The drive motor 10 that has received the control signal starts rotational drive, and this drive force is transmitted to the ball screw shaft 24 via the planetary gear reduction mechanism 18, the drive gear 30, the driven gear 31, and the ball screw nut 23. As a result, the ball screw shaft 24 advances (or retreats) in a direction parallel to the output shaft 10a of the drive motor 10. As a result, the operation target arranged on the tip side (actuator head side) of the ball screw shaft 24 is operated.

At this time, the magnetic sensor 70 detects the stroke value (axial position) of the ball screw shaft 24. The detection value detected by the magnetic sensor 70 is sent to the comparison unit 82 of the control device 80, and the difference between the detection value and the target value is calculated. Then, the drive motor 10 is driven until the detected value matches the target value. By thus feeding back the stroke value detected by the magnetic sensor 70 and controlling the position of the ball screw shaft 24, when the electric actuator 1 of the present embodiment is applied to, for example, shift-by-wire, the shift position is changed. Can be reliably controlled.

The configuration and operation of the electric actuator 1 of this embodiment are as described above. Hereinafter, the effects of the present invention will be described with respect to the electric actuator 1 of the present embodiment.

As described above, in the electric actuator 1 of the present embodiment, the boot 36 is arranged between the ball screw shaft 24 as a movable part and the cylindrical portion 29g of the transmission gear case 29 arranged around the ball screw shaft 24, and A permanent magnet 73 is arranged in a portion of the screw shaft 24 covered with the boot 36, and a magnetic sensor 70 is arranged in a boot cover 39 covering the boot 36. Therefore, the boot 36 can prevent foreign matter from entering the inside of the ball screw 22 as the motion converting mechanism. Further, although the boot 36 exists between the magnetic sensor 70 and the permanent magnet 73 as a sensor target, since the boot 36 is made of resin or rubber, it does not interfere with the detection of the magnetic field by the magnetic sensor 70. Therefore, the position of the ball screw shaft 24 in the linear movement direction can be accurately detected while the inside of the ball screw 22 is sealed by the boot 36. Further, by disposing the permanent magnet 73 in the portion of the ball screw shaft 24 covered by the boot 36, deterioration and damage due to exposure of the permanent magnet 73 to the outside air can be prevented as much as possible. It is possible to exert a highly accurate position detection function for a long period of time.

If the reduction gear mechanism 9 and the lock mechanism portion 7 are unnecessary, the electric actuator 1 having neither the reduction gear mechanism portion 9 nor the lock mechanism portion 7 can be configured as shown in FIG. The electric actuator 1 shown in FIG. 17 is different from the electric actuator 1 shown in FIG. 1 in that the reduction gear mechanism section 9 is eliminated, the motor section 8 and the driving force transmission section 4 are directly connected, and the shaft case 50 is locked by the lock mechanism section. 7 is replaced with one without a holder 66. In this case, since the output shaft 10a of the drive motor 10 does not have the reduction gear mechanism 9, the rolling bearing 33 on the side of the transmission gear case 29 that press fits into the gear boss 32 and supports the gear boss 32 is omitted. Further, the motor adapter 19 to which the output shaft 10a of the drive motor 10 is attached has a different mating member changed from the reduction gear case 17 to the transmission gear case 29. Are changing. Other configurations are similar to those of the embodiment shown in FIG. The electric actuator 1 of the embodiment shown in FIG. 17 differs from the electric actuator 1 of the embodiment shown in FIG. 1 except that the driving force from the driving motor 10 is directly transmitted to the driving force transmission unit 4 without passing through the speed reduction mechanism unit 9. The operation is basically controlled and operated in the same manner, and therefore the description of the control and operation will be omitted.

As described above, in the electric actuator 1 shown in FIG. 1 and the electric actuator 1 shown in FIG. 17, many parts can be configured by common parts only by exchanging some parts, and at low cost. A series can be realized. In particular, in the embodiment described above, the inner diameter of the motor case 11 on the side of the opening 12d, the outer diameter of the reduction gear case 17 on the side of the motor case 11 and the outer diameter of the transmission gear case 29 on the side of the reduction gear case 17 are the same. The motor case 11 is configured to be fittable with both the reduction gear case 17 and the transmission gear case 29. Therefore, even if the deceleration mechanism section 9 is omitted, the motor section 8 and the driving force transmission section 4 can be connected to each other only by replacing the motor adapter 19 with another one. Further, since the motor case 11 and the transmission gear case 29, which are integrally formed with the boot cover 39, can be used as they are without any change, the magnetic sensor 70 and the sensor base 71 which form the position detecting device are the same as those in the previous embodiment. , The exact same can be used. This makes it possible to achieve a series of electric actuators 1 at low cost even when the position detection device is mounted. In addition, as a specific example of the development of various kinds with the series of the electric actuator 1, as an electric parking brake mechanism for an automobile including a motorcycle, an electric hydraulic brake mechanism, an electric shift switching mechanism, an electric power steering, and 2WD/4WD. An electric switching mechanism, an electric shift switching mechanism for outboard motors (for marine propulsion machines), and the like can be exemplified.

FIG. 18 shows a cross-sectional view of the electric actuator 1 according to another embodiment of the present invention. As shown in this figure, the electric actuator 1 according to the present embodiment is different from that shown in FIG. 1 in that the magnetic shield plate 101 is disposed around the drive motor 10 and between the magnetic sensor 70 and the magnetic sensor 70. The electric actuator 1 shown in FIG.

This magnetic shield plate 101 has a cylindrical shape in the present embodiment, and is arranged between the drive motor 10 and the case body 12 of the motor case 11. Note that, in order to facilitate the assembling to the inner circumference of the case body 12, the magnetic shield plate 101 may have a shape in which a notch is provided in a part in the circumferential direction, as shown in FIG.

The magnetic shield plate 101 may be made of a magnetic material, but from the viewpoint of preventing the leakage of magnetic flux to the outside of the drive motor 10, a material having a high magnetic permeability such as pure iron or low carbon steel (for example, for drive). It is preferable to form the yoke of the motor 10).

As described above, by disposing the magnetic shield plate 101 around the drive motor 10, the magnetic field generated by the drive motor 10 is blocked before the magnetic sensor 70, so that the magnetic sensor 70 originally detects the magnetic field. It is possible to accurately detect only the magnetic field to be generated (the magnetic field generated by the permanent magnet 73) and to accurately detect the position of the ball screw shaft 24 in the linear movement direction.

Further, in the present embodiment, since the magnetic shield plate 101 has a cylindrical shape and is arranged between the drive motor 10 and the case body 12, the drive motor 10 is covered with the magnetic shield plate 101 over the entire circumference thereof. It becomes a state. In this case, the magnetic shield plate 101 can form a closed magnetic circuit together with the motor as a kind of yoke, so that the magnetic field (specifically, magnetic flux) generated by the magnet in the drive motor 10 is used for driving. It is possible to prevent the situation of leaking to the outside of the motor 10 as much as possible. Therefore, the influence of the magnetic field exerted on the magnetic sensor 70 can be more surely eliminated, and more accurate position detection can be achieved.

The shape of the magnetic shield plate 101 is arbitrary, and although not shown, for example, two semi-cylindrical magnetic shield plates obtained by dividing the cylindrical magnetic shield plate 101 into two may be used. Further, the magnetic shield plates 101 having the above-mentioned configuration may be used by being doubled. Alternatively, it may be formed integrally with the motor case 11, and may be, for example, an injection-molded product of resin using the magnetic shielding plate 101 as an insert component. In this case, the magnetic shield plate 101 is not limited to a cylindrical shape and can take various forms.

FIG. 19 shows a cross-sectional view of an essential part of an electric actuator 1 according to another embodiment of the present invention. This cross-sectional view is a cross-sectional view obtained by virtually cutting the electric actuator 1 at the same position as the cross-section shown in FIG. As shown in FIG. 19, the electric actuator 1 according to the present embodiment includes a plurality of permanent magnets 73 forming a sensor target in the stroke direction for the purpose of enlarging the area detectable by the magnetic sensor 70 in the stroke direction (FIG. 19). In this case, 3 pieces are arranged side by side. In this case, the plurality of permanent magnets 73 are arranged along the magnetization direction (direction orthogonal to both end surfaces 73a and 73b), and the N pole (one end surface 73a) and the S pole (other end surface 73b) are arranged. And are arranged so that they are alternately arranged. Therefore, also in this case, the magnetizing direction of the permanent magnet 73 coincides with the linear movement direction of the ball screw shaft 24 (see FIG. 19).

Further, in this case, as the magnet holder 74, one having a plurality of pairs of fitting claws 741 and a fitting recess 742 into which the permanent magnet 73 can be fitted is integrally used as in the case shown in FIG. It In the present embodiment, two magnet holders 74 are used, and the side opposite to the first sandwiching portion 744 forming the fitting recess 742, that is, the opening side of the fitting recess 742 (the opening 746 shown in FIG. 14). The two magnet holders 74 are fitted to the cutout portions 241 of the ball screw shaft 24 so that the fitting recesses 742 and 742 are in a state where the fittable volume is increased. Are attached by fitting. In this case, a plurality of permanent magnets 73 are sandwiched between the first sandwiching portions 744 and 744 that form the fitting recess 742 in each magnet holder 74. Therefore, the second holding portion 745 (see FIG. 14) formed separately from the fitting claw 741 and the like can be omitted.

Further, when the sensor target is arranged on the ball screw shaft 24 as described above, the boot 36 is interposed between any of the permanent magnets 73 and the magnetic sensor 70. As described above, by disposing all the permanent magnets 73 in the portion of the ball screw shaft 24 covered with the boot 36, it is possible to prevent the permanent magnets 73 from being deteriorated or damaged by being exposed to the outside air. Therefore, even when a plurality of permanent magnets 73 are provided, it is possible to exert a highly accurate position detection function for a long period of time.

Further, in the above embodiment, the case where both the speed reduction mechanism unit 9 and the lock mechanism unit 7 are provided and the case where both are not provided have been described as an example, but an electric actuator having either one may be configured. .. Further, in the above example, the shaft case 50 is changed depending on the presence or absence of the lock mechanism portion 7, but the shaft case 50 is changed to a different shape or size according to the length of the ball screw shaft 24. May be.

The motion conversion mechanism section 3 is not limited to the ball screw 22 and may be a slide screw device. However, from the viewpoint of reducing the rotating torque and downsizing the drive motor 10, the ball screw 22 is preferable. In addition, in the above-described embodiment, a configuration in which a double row angular ball bearing is used as the support bearing 40 that supports the motion conversion mechanism portion 3 is illustrated, but the present invention is not limited to this, and a pair of single row angular ball bearings is used. You may use it in combination. Further, the support bearing 40 is not limited to the angular contact ball bearing, and it is also possible to apply, for example, another double row bearing using a deep groove ball bearing or the like.

The reduction gear mechanism 9 may be a reduction gear mechanism other than the planetary gear reduction mechanism 18. Further, the driving force transmission unit 4 may also function as a speed reduction mechanism by changing the gear ratio between the drive gear 30 and the driven gear 31.

Further, the present invention is not limited to the above-described embodiments, and it goes without saying that the present invention can be implemented in various forms within the scope of the present invention, and the scope of the present invention is not limited to this. , And the equivalent meanings set forth in the claims, and all modifications within the scope.

DESCRIPTION OF SYMBOLS 1 Electric actuator 2 Drive part 3 Motion conversion mechanism part 4 Driving force transmission part 5 Motion conversion mechanism support part 6 Operation part 7 Lock mechanism part 8 Motor part 9 Reduction mechanism part 10 Drive motor 10a Output shaft 11 Motor case 16 Reduction gear mechanism 17 Reduction Gear Case 22 Ball Screw (Motion Conversion Mechanism)
24 Ball screw shaft (movable part)
28 Transmission Gear Mechanism 29 Transmission Gear Case 36 Boot 39 Boot Cover 40 Support Bearing 41 Bearing Case 50 Shaft Case 70 Magnetic Sensor 73 Permanent Magnet 101 Magnetic Shielding Plate

Claims (5)

A motor and a motion conversion mechanism that converts a rotational motion generated by driving the motor into a linear motion in a direction parallel to the output shaft of the motor, and the motion conversion mechanism is disposed in parallel with the output shaft. In an electric actuator having a movable part that performs the linear movement,
A resin or rubber boot is disposed between the movable portion and a fixed system around the movable portion, and a magnet is disposed in a portion of the movable portion covered with the boot,
A magnetic sensor for detecting the position of the magnet in the linear movement direction is arranged around the boot ,
The magnet is attached to the movable portion via a magnet holder that holds the magnet, and the magnetic sensor is attached to a boot cover that covers the periphery of the boot,
An electric actuator , wherein both the magnet holder and the boot cover are made of a non-magnetic material . The magnetic sensor includes an electric actuator according to claim 1 is a Hall IC. The electric actuator according to claim 1 or 2 , wherein a magnetizing direction of the magnet attached to the movable portion matches a linear movement direction of the stroke portion. Of the periphery of the motor, at least an electric actuator according to any one of claims 1 to 3, the magnetic shield plate is arranged between the magnetic sensor. The electric actuator according to claim 4 , wherein the magnetic shield plate has a cylindrical shape, and is arranged between the motor and a motor case that houses the motor.

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