JP2018159406A - Electric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric actuator excellent in assemblability and operation accuracy of a screw shaft.SOLUTION: An electric actuator 1 includes: a motor part A; a motion converting mechanism part B; an operation part C operating an operational object; and a bottomed cylindrical case 2 housing the motor part A and the motion converting mechanism part B. The motion converting mechanism part B has a screw shaft 33 and a nut 32 rotatably engaged with its outer periphery, and an actuator head 39 moves forward and backward in an axial direction as the screw shaft 33 and the operation part C when the nut 32 rotates. Clearance fitting of a projection P provided for the actuator head 39 occurs to an inner periphery of a recess R provided for one end part in the axial direction of the screw shaft 33, the screw shaft 33 and the actuator head 39 are engaged in an engaging area of the recess R and the projection P in the axial direction, so that the screw shaft 33 and the actuator head 39 are joined. The recess R provided for the screw shaft 33 can project outside and be housed in the case 2 via an opening of the case 2 in a stop state of the motor part A.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an electric actuator.

  In recent years, in various vehicles such as automobiles and motorcycles, electrification has progressed in order to save labor and reduce fuel consumption. For example, a system that performs operation of an automatic transmission, a brake, a steering, and the like with the power of an electric motor (motor). Has been developed and put on the market. As an electric actuator used in such a system, there is one that employs a ball screw mechanism (ball screw device), which is a kind of screw mechanism, as a motion conversion mechanism that converts a rotational motion of a motor into a linear motion and outputs the motion ( For example, Patent Document 1).

JP-A-2005-330942

  In an electric actuator that employs a ball screw device as a motion conversion mechanism, an operation unit for operating the operation target is provided on the screw shaft in accordance with the application, the shape of the operation target, and the like. In this regard, Patent Document 1 employs a configuration in which an operation unit is integrally provided on a screw shaft. However, when such a configuration is adopted, the output member (final output member) of the electric actuator including the operation unit and the screw shaft needs to be a dedicated part corresponding to the application, the shape of the operation target, and the like. . Therefore, there is a problem that it is not possible to realize the series of electric actuators (multi-product development) by sharing parts at low cost.

  Accordingly, the inventors of the present application have a screw shaft and an operating portion as separate bodies, and in the final stage of the assembly process of the electric actuator, a recess provided in either the screw shaft (one end portion in the axial direction thereof) or the operating portion. On the other hand, it was studied to fix both of them by press-fitting a convex portion provided on the other side. However, in this case, since the press-fitting load when fixing the operation unit to the screw shaft is applied not only to the screw shaft (including the ball screw device) but also to the motor and actuator housing, each part of the electric actuator Deformation / damage may cause adverse effects on the operating accuracy of the screw shaft.

  Such a problem can be solved as much as possible by press-fitting a convex portion provided on the other side with respect to a concave portion provided on either the screw shaft or the operating portion in the state of the ball screw device alone, for example. Can do. However, in this case, the assembling property between the ball screw device and the other parts, and the assembling property of the electric actuator is lowered.

  In view of the above circumstances, a main object of the present invention is to provide an electric actuator that is excellent in assembling of an operation portion with respect to a screw shaft and has a good operation accuracy of the screw shaft.

  The present invention, which was created to solve the above problems, operates a motor unit, a motion conversion mechanism unit that converts the rotational motion of the motor unit into a linear motion, and receives an output from the motion conversion mechanism unit to operate an operation target. The operation unit and an end in the axial direction are opened, and a bottomed cylindrical casing that houses the motor unit and the motion conversion mechanism unit is provided. The motion conversion mechanism unit is arranged coaxially with the rotation center of the motor unit. An electric actuator having a screw shaft and a nut that is fitted to the outer periphery of the screw shaft and that rotates by receiving the rotational motion of the motor unit, and the screw shaft and the operation unit move back and forth in the axial direction as the nut rotates. , The convex portion provided on the other is fitted into the inner periphery of the concave portion provided on one end of the axial direction of the screw shaft and the operating portion, and the screw shaft and the operating portion are fitted to the concave portion and the convex portion. Operation with the screw shaft by axially engaging in the joint area : It is connected, recesses or protrusions provided on the screw shaft, characterized in that in the stop state of the motor unit via the opening of the housing can be projected and housed in an outer casing. The definition of “clearance fit” here is based on the provisions of Japanese Industrial Standard JIS B0401-1.

  According to the above configuration, since the operation unit is provided separately from the screw shaft, the required output is equivalent when considering various types of electric actuators (use in different applications). As long as the operation unit is changed, the operation unit may be changed to one having a different specification, and the motion conversion mechanism unit and the motor unit including the screw shaft can be shared.

  Moreover, according to said structure, when an operation part is connected and fixed to a screw shaft, the press-fit load of an axial direction does not act on a motion conversion mechanism part, a housing | casing, etc. For this reason, it is possible to effectively reduce the possibility that each part of the electric actuator is deformed / damaged along with the operation of connecting the operation part to the screw shaft. Further, since the concave portion or the convex portion provided on the screw shaft (one end portion in the axial direction thereof) can be projected and accommodated outside the housing through the opening of the housing with the motor portion stopped. The operation of connecting the operation unit to the screw shaft can be easily performed at the final stage of the assembly process of the electric actuator. As described above, according to the present invention, it is possible to provide an electric actuator that can be applied to various devices, has high versatility, is excellent in assembling of the operation unit, and is excellent in the operation accuracy of the screw shaft.

  The screw shaft and the operation portion are, for example, by inserting a pin through a radial through hole provided in a recess and a convex portion (one end portion of the screw shaft in the axial direction and the operation portion), or the inner peripheral surface of the recess The male screw portion provided on the outer peripheral surface of the convex portion is screwed to the female screw portion provided on the outer peripheral surface of the convex portion, so that they can be engaged in the axial direction.

  In the above configuration, the screw shaft is provided with a rotating body that can rotate about a radial axis, and a cylindrical guide member is detachably connected to one end portion of the casing in the axial direction, and the rotating member is connected to the guide member. Are fitted so as to be able to roll, and an axial guide groove for determining the forward / backward movement amount (stroke amount) of the screw shaft can be provided. In this way, for example, even when the electric actuator is deployed in an application where the required stroke amount of the screw shaft is different, the guide member may be replaced with a guide member having a different axial dimension. It becomes possible to share the motion conversion mechanism and the housing that houses them. Therefore, it is advantageous in realizing an electric actuator that can be easily developed (series).

  The electric actuator having the above-described configuration may further include a hollow rotating shaft that supports the rotor core of the motor unit and a rolling bearing that rotatably supports the hollow rotating shaft. In this case, the nut is hollow. It is possible to adopt a configuration in which the inner shaft surface of the rolling bearing is provided on the inner periphery of the hollow rotating shaft so that torque can be transmitted to the rotating shaft. By adopting such a configuration, it is possible to use a hollow rotating shaft that is compact in the axial direction, so that the electric actuator can be made compact in the axial direction and the mountability to the equipment used can be improved.

  When the inner raceway surface is provided on the hollow rotary shaft, the inner raceway surface can be disposed inside the axial width of the nut. Thereby, the electric actuator can be made more compact in the axial direction.

  As described above, according to the present invention, it is possible to provide an electric actuator that can be applied to various devices, has high versatility, is excellent in assembling of the operation portion with respect to the screw shaft, and has good operation accuracy of the screw shaft. .

1 is a longitudinal sectional view of an electric actuator according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line EE in FIG. 1. It is the longitudinal cross-sectional view which took out the stator and terminal part of the motor, and was expanded. It is a GG arrow directional cross-sectional view of FIG. It is a HH arrow directional cross-sectional view of FIG. It is a left view of FIG. FIG. 5 is a cross-sectional view taken along line F-F in FIG. 2. It is a front view explaining the assembly method of a guide member. It is a front view explaining the assembly | attachment method of the guide member from which an axial direction differs. It is a principal part expansion longitudinal cross-sectional view of an electric actuator, Comprising: It is a figure which shows the state which the connection operation | work of the actuator head with respect to a screw shaft was completed. It is a figure which shows the state which the connection operation | work of the actuator head which concerns on a modification with respect to a screw shaft was completed. It is a perspective view explaining the connection method of the screw axis and actuator head concerning other embodiments. It is a schematic block diagram which shows the control system of the electric actuator of FIG. It is a schematic block diagram which shows the control system of the electric actuator which concerns on other embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a longitudinal sectional view of an electric actuator according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line EE in FIG. As shown in FIGS. 1 and 2, the electric actuator 1 includes a motor unit A that is driven by the supply of electric power, a motion conversion mechanism unit B that converts the rotational motion of the motor unit A into a linear motion, The motor unit A, the motion conversion mechanism unit B, and the terminal unit D are accommodated and held in a bottomed cylindrical casing 2. 1 and 2 show a state where the output member of the electric actuator 1 is located at the origin. The “state located at the origin” here means that the end surface of the screw shaft 33 (the inner member 36 connected to the screw shaft 33) is opposed to this by the spring force (elastic restoring force) of the compression coil spring 48 described later. This is a state where it is in a position where it mechanically contacts the end face of the cover 29.

  The housing | casing 2 consists of a some member couple | bonded with the axial direction. The housing 2 of the present embodiment has one end in the axial direction (on the right side in FIG. 1 and FIG. 2, the same applies hereinafter) and the other end in the axial direction (the left side in FIG. 1 and FIG. 2, the same applies hereinafter). A cylindrical casing 20 having a portion opened, a cover 29 that closes an end opening on the other axial side of the casing 20, a terminal body 50 that is disposed between the casing 20 and the cover 29 and constitutes the terminal portion D, It consists of a combined body with the cylindrical guide member 10 arrange | positioned at the axial direction one side of the casing 20. As shown in FIG. The cover 29 and the terminal main body 50 are connected to the casing 20 by an assembly bolt 61 shown in FIG. 6, and the guide member 10 is detachably connected to the casing 20 by means described later.

  The motor portion A is a radial gap type motor (in detail, including a stator 23 fixed to the inner periphery of the casing 20 and a rotor 24 disposed to face the inner periphery of the stator 23 via a radial gap. A three-phase brushless motor having a U phase, a V phase and a W phase). The stator 23 includes an insulating bobbin 23b attached to the stator core 23a, and a coil 23c wound around the bobbin 23b. The rotor 24 includes a rotor core 24a, a permanent magnet 24b attached to the outer periphery of the rotor core 24a, and a rotor inner 26 formed as a hollow shaft and supporting the rotor core 24a (mounted on the outer periphery) as a hollow rotary shaft.

  An inner raceway surface 27 a of the rolling bearing 27 is formed on the outer periphery of the end portion on one axial side of the rotor inner 26, and an outer ring 27 b of the rolling bearing 27 is attached to the inner peripheral surface of the casing 20. Further, a rolling bearing 30 is mounted between the inner peripheral surface of the other end in the axial direction of the rotor inner 26 and the outer peripheral surface of the cylindrical portion 29 a of the cover 29. With such a configuration, the rotor inner 26 is rotatably supported with respect to the housing 2 via the rolling bearings 27 and 30. The rolling bearing 27 is disposed inside the axial width of a nut 32 to be described later.

  As shown in FIGS. 1 and 2, the motion conversion mechanism B of the present embodiment includes a ball screw device 31.

  The ball screw device 31 is arranged coaxially with the rotor 24 (rotor inner 26), and together with an actuator head 39 as the operation portion C, a screw shaft 33 that constitutes an output member of the electric actuator 1, and a screw shaft via a plurality of balls 34. A nut 32 rotatably fitted to the outer periphery of 33 and a top 35 as a circulation member are provided. A plurality of balls 34 are loaded between the spiral groove 32 a formed on the inner peripheral surface of the nut 32 and the spiral groove 33 a formed on the outer peripheral surface of the screw shaft 33, and the top 35 is incorporated. The nut 32 is fixed (press-fitted in this embodiment) to the inner periphery of the rotor inner 26 so that torque can be transmitted to the rotor inner 26 of the motor 25. With this configuration, when the nut 32 rotates around the axis of the screw shaft 33 in response to the rotational movement of the motor part A (rotor inner 26), the screw shaft 33 linearly moves (advances and retreats) in the axial direction. When the screw shaft 33 moves back and forth, the ball 34 circulates between the spiral grooves 32a and 33a.

  The screw shaft 33 is formed in a hollow shape whose both ends in the axial direction are open, and an inner member 36 is accommodated on the inner periphery. The inner member 36 is made of, for example, a resin material such as PPS, and has a circular solid portion 36a provided at an end portion on one side in the axial direction, a flange portion 36b provided at an end portion on the other side in the axial direction, It has a bottomed cylindrical shape integrally having a cylindrical portion 36c that connects both portions 36a and 36b. The inner member 36 accommodated in the inner periphery of the screw shaft 33 is connected to the screw shaft 33 by fitting a pin 37 so as to penetrate the circular solid portion 36a and the screw shaft 33 in the radial direction. Both end portions of the pin 37 protrude radially outward from the outer peripheral surface of the screw shaft 33, and a guide collar 38 as a rotating body formed of a resin material such as PPS is fitted on the protruding portion.

  The casing 20 has a small diameter cylindrical portion 20a, and a cylindrical guide member 10 is detachably connected to the small diameter cylindrical portion 20a. The guide collar 38 is fitted in an axial guide groove 11 provided on the inner periphery of the guide member 10, and rolls on the guide groove 11 when the screw shaft 33 moves forward and backward. With this configuration, when the nut 32 rotates around the axis of the screw shaft 33 as the motor 25 rotates, the screw shaft 33 moves forward and backward in the axial direction while being prevented from rotating. Whether the screw shaft 33 linearly moves (moves forward) on one side in the axial direction or linearly moves (retreats) on the other side in the axial direction is basically determined according to the rotation direction of the nut 32. However, in this embodiment, the screw shaft 33 can also be moved backward by the spring force of the compression coil spring 48 as an urging member (details will be described later).

  As shown in FIG. 1 and FIG. 2, an actuator head 39 as an operation portion C is connected to one end of the screw shaft 33 in the axial direction, and the screw shaft 33 and the actuator head 39 connected thereto are connected. Thus, the output member of the electric actuator 1 is configured. As the actuator head 39, one according to the application of the electric actuator 1 is selectively used. The illustrated actuator head 39 is a so-called push-type actuator head that pressurizes an operation target (not shown) in the axial direction as the screw shaft 33 moves forward.

  As shown in FIGS. 1 and 2, the cover 29 has a cylindrical portion 29a disposed on the outer periphery of the screw shaft 33, and a thrust receiving ring 46 is attached to the outer periphery of the tip portion of the cylindrical portion 29a. A needle roller bearing 47 as a thrust bearing is disposed between the thrust receiving ring 46 and the nut member 32. By disposing the needle roller bearing 47 in this manner, the reaction force (thrust load) generated when the screw shaft 33 linearly moves in one axial direction is smoothly supported.

  The needle roller bearing 47 is disposed within an axial range between the rolling bearings 27 and 30 that support the rotor inner 26. In this case, since it is advantageous with respect to the moment load, it is possible to adopt small-sized needle roller bearings 47, thrust receiving rings 46, and the like, and the electric actuator 1 can be made compact.

  As shown in FIGS. 1 and 2, a compression coil spring 48 as an urging member is disposed between the inner peripheral surface 29 b of the cylindrical portion 29 a of the cover 29 and the outer peripheral surface of the screw shaft 33. Ends on one side and the other side in the axial direction of the compression coil spring 48 are in contact with the needle roller bearing 47 and the flange portion 36b of the inner member 36, respectively. Due to the spring force of the compression coil spring 48 thus provided, the screw shaft 33 connected to the inner member 36 is always biased toward the origin. In this way, for example, when the driving power is not properly supplied to the motor unit A, the screw shaft 33 can be automatically returned to the origin, so that the operability of the operation target (not shown) is adversely affected. And it becomes difficult.

  The cover 29 described above is formed of a metal material excellent in workability (mass productivity) and thermal conductivity, for example, an aluminum alloy, a zinc alloy, or a magnesium alloy. Although not shown, a cooling fin for increasing the cooling efficiency of the electric actuator 1 may be provided on the outer surface of the cover 29. As shown in FIG. 6, a through-hole (not shown) through which the assembly bolt 61 of the electric actuator 1 is inserted and a mounting bolt for attaching the electric actuator 1 to a device to be used are inserted in the outer periphery of the cover 29. A through hole 62 is provided.

  Next, the terminal part D is demonstrated with reference to FIGS. As shown in FIG. 3, the terminal portion D has a short cylindrical portion constituting a part of the housing 2 and a disk-shaped portion extending radially inward from the other axial end of the short cylindrical portion. And a bus bar 51 and a printed circuit board 52 screwed to the terminal main body 50 (the disk-shaped portion thereof). As shown in FIGS. 4 and 5, the short cylindrical portion of the terminal body 50 is inserted with a through hole 68 through which the assembly bolt 61 shown in FIG. 6 is inserted, and a bolt for attaching the electric actuator 1 to a device to be used. And is sandwiched between the casing 20 and the cover 29 by the assembly bolt 61 (see FIGS. 1 and 2). The terminal body 50 is formed of a resin material such as PPS, for example.

  The terminal portion D (terminal body 50) holds a power feeding circuit for supplying driving power to the motor 25. As shown in FIGS. 4 and 5, the power feeding circuit connects the coils 23c of the stator 23 to the terminals 51a of the bus bar 51 for each of the U phase, the V phase, and the W phase. Further, as shown in FIG. The terminal 51 b of 51 and the terminal block 50 a of the terminal body 50 are fastened with screws 70. The terminal block 50a has a terminal 50b to which a lead wire (not shown) is connected. The lead wire is connected to the housing via an opening 50c (see FIG. 1) provided in the short cylindrical portion of the terminal body 50. It is pulled out of the body 2 and connected to the controller 81 (see FIG. 13 or FIG. 14) of the control device 80.

  Two types of sensors are mounted on the electric actuator 1 of the present embodiment, and these two types of sensors are held in the terminal portion D. As shown in FIG. 1 and the like, one of the two types of sensors is a rotation angle detection sensor 53 used for rotation control of the motor 25, and the other is stroke control (detection of displacement in the axial direction) of the screw shaft 33. This is a stroke detection sensor 55 used for As the rotation angle detection sensor 53 and the stroke detection sensor 55, a Hall sensor which is a kind of magnetic sensor is used.

  As shown in FIGS. 1 and 5, the rotation angle detection sensor 53 is attached to a printed circuit board 52 having a disk shape, and a pulsar ring 54 attached to an end portion on the other side in the axial direction of the rotor inner 26 and a shaft. Oppositely arranged via a directional gap. The rotation angle detection sensor 53 determines the timing for supplying current to each of the U phase, V phase, and W phase of the motor 25.

  As shown in FIGS. 2 and 5, the stroke detection sensor 55 is attached to a belt-like printed circuit board 56 extending in the axial direction and having an end on the other side in the axial direction connected to the printed circuit board 52. The printed circuit board 56 and the stroke detection sensor 55 are arranged on the inner periphery of the screw shaft 33, more specifically, on the inner periphery of the cylindrical portion 36 c of the inner member 36 housed on the inner periphery of the screw shaft 33. In addition, a permanent magnet 57 as a target is attached to the inner periphery of the cylindrical portion 36c of the inner member 36 so as to face the stroke detection sensor 55 via a radial gap. Permanent magnets 57 are attached to two locations separated from each other. The stroke detection sensor 55 including a hall sensor detects axial and radial magnetic fields formed around the permanent magnet 57, and calculates the axial displacement of the screw shaft 33 based on the detected axial magnetic field and radial magnetic field. .

  Although detailed illustration is omitted, the signal lines of the rotation angle detection sensor 53 and the stroke detection sensor 55 are both outside the housing 2 through the opening 50c (see FIG. 1) of the terminal body 50. And connected to the control device 80 (see FIG. 13 or FIG. 14).

  The basic configuration of the electric actuator 1 of the present embodiment is as described above, and this electric actuator 1 can exhibit the following operational effects.

  First, the rotor inner 26 as a hollow rotating shaft is rotatably supported at one end in the axial direction by a rolling bearing 27 disposed in the vicinity of one end in the axial direction of the rotor core 24a, and the other in the axial direction of the rotor core 24a. The other end portion in the axial direction is rotatably supported by a rolling bearing 30 disposed close to the end portion on the side. With such a structure, the rotor inner 26 can be made compact in the axial direction. In addition to this, the structure in which the rolling bearing 27 is disposed inside the axial width of the nut 32 and the overlapping structure in the radial direction of the rotor inner 26 and the nut 32 are combined to form the casing 2 and, consequently, the electric actuator 1. Can be made compact in the axial direction and the radial direction. Thereby, the mounting property with respect to the use apparatus of the electric actuator 1 improves.

  Usually, the rotor 24 is rotationally balanced. In this case, since the rolling bearings 27 and 30 that support the rotor inner 26 are only required to support a radial load about the weight of the rotor 24, the rotor inner 26 integrally including the inner raceway surface 27a of the rolling bearing 27 is made of a high-strength material. There is no need to form, for example, the required strength can be ensured even if it is made of an inexpensive mild steel material in which heat treatment such as quenching and tempering is omitted. The reaction force (thrust load) generated along with the linear motion of the screw shaft 33 is supported by a dedicated needle roller bearing 47. Accordingly, since the rolling bearing 27 only needs to have a radial positioning function, the rotor inner 26 integrally including the inner raceway surface 27a of the rolling bearing 27 is sufficient for the material specifications as described above. Thereby, the cost of the electric actuator 1 can be reduced.

  In addition, since the rotor inner 26 and the nut 32 have a separate structure, for example, even when the ball screw device 31 having different specifications is adopted, the rotor inner 26 (and thus the motor part A) can be shared. As a result, it is possible to easily realize a wide variety (series) of electric actuators 1 by sharing parts.

  In addition, electrical components such as a power feeding circuit, a rotation angle detection sensor 53, and a stroke detection sensor 55 are collectively held by the terminal body 50, and the terminal body 50 (terminal portion D) is axially formed by the casing 20 and the cover 29. Since the sandwich structure sandwiched between the two is adopted, the assemblability is good. Further, the lead wire of the power feeding circuit and the signal line of the sensor can be drawn out of the housing 2 through the sandwich structure and the opening 50c provided on the outer peripheral portion (short cylindrical portion) of the terminal body 50. With this structure, a plurality of electric actuators 1 (units of motor part A, motion conversion mechanism part B and terminal part D) are arranged in the axial direction, and a plurality of operation objects can be operated individually. A simple electric actuator can also be realized.

  The electric actuator 1 according to the present embodiment includes a characteristic configuration described below in addition to the characteristic configuration described above. Details thereof will be described with reference to FIGS. 1, 2, and 7 to 12.

  First, as shown in FIGS. 1 and 2, the cylindrical guide member 10 that guides the linear motion of the screw shaft 33 is detachably connected to an end portion on one axial side of the housing 2 (casing 20). ing. That is, the guide member 10 has an axial guide groove 11 in which a guide collar 38 provided on the screw shaft 33 is fitted so as to be able to roll, and the guide groove 11 is necessary depending on the use of the electric actuator 1. It has an axial dimension corresponding to the stroke amount of the screw shaft 33. The guide member 10 includes an inner diameter side cylindrical portion 10A in which a guide groove 11 is formed on the inner peripheral surface, an outer diameter side cylindrical portion 10B provided on the radially outer side of the inner diameter side cylindrical portion 10A, and both cylindrical portions 10A and 10B. Is integrally formed with the disk portion 10C, and between the cylindrical portions 10A and 10B (between the outer peripheral surface 10Aa of the inner diameter side cylindrical portion 10A and the inner peripheral surface 10Ba of the outer diameter side cylindrical portion 10B), An annular groove 12 into which the small diameter cylindrical portion 20a of the casing 20 is fitted is formed.

  In consideration of the assembly of the guide member 10 to the casing 20, the fit between the inner peripheral surface 10Ba of the outer diameter side cylindrical portion 10B and the outer peripheral surface of the small diameter cylindrical portion 20a of the casing 20 and the outer periphery of the inner diameter side cylindrical portion 10A The fit between the surface 10Aa and the inner peripheral surface of the small-diameter cylindrical portion 20a of the casing 20 is a clearance fit (see Japanese Industrial Standard JIS B 0401-1). Although not shown, a seal member such as an O-ring is disposed between the outer diameter side cylindrical portion 10B of the guide member 10 and the small diameter cylindrical portion 20a of the casing 20 as necessary, whereby the casing The sealing property between 20 and the guide member 10 is ensured. The guide member 10 is pushed in until the free end of the small diameter cylindrical portion 20a of the casing 20 contacts the groove bottom surface 12a of the annular groove 12 (the end surface on the other side in the axial direction of the disk portion 10C). By inserting a pin (for example, a spring pin) 13 between the diameter-side cylindrical portion 10B and the small-diameter cylindrical portion 20a of the casing 20, the relative movement with respect to the casing 20 is restricted and coupled to the casing 20.

  A connection structure between the casing 20 and the guide member 10 employed in the present embodiment will be described in detail with reference to FIGS. 7 and 8. As shown in FIG. 7, the outer diameter side cylindrical portion 10B of the guide member 10 has a notch portion 10D formed at two locations spaced in the circumferential direction and a through hole 10E opened to the two notch portions 10D. And are provided. Moreover, the notch part 20b along the extending direction of said through-hole 10E is formed in the outer peripheral surface of the small diameter cylindrical part 20a of the casing 20. As shown in FIG. Then, as shown in FIG. 8, the small-diameter cylindrical portion 20a of the casing 20 is fitted into the annular groove 12 of the guide member 10 in a state in which the through hole 10E and the notch portion 20b are phase-matched. When the free end contacts the groove bottom surface 12a of the annular groove 12, the pin 13 is inserted into the through hole 10E. As a result, the guide member 10 is connected and fixed to the casing 20 such that relative movement and relative rotation in the axial direction with respect to the casing 20 (housing 2) are restricted.

  According to the configuration (procedure) described above, the guide member 10 can be easily and accurately connected to the casing 20. Although detailed illustration is omitted, the guide member 10 can be separated from the casing 20 by removing the pin 13 and then moving the guide member 10 and the casing 20 relatively apart. For this reason, the guide member 10 can be easily changed to a guide member 10 ′ having a different axial dimension (of the guide groove 11), for example, as shown in FIG. 9. The guide member 10 ′ shown in FIG. 9 has an axial dimension W2 larger than the guide member 10 shown in FIG. 8 (the guide member 10 whose axial dimension is W1), and the axial dimension of the guide groove 11 is extended. Except for the above, the structure is substantially the same as that of the guide member 10 shown in FIG.

  Therefore, the electric actuator 1 of the present embodiment is necessary for the screw shaft 33 while sharing most of the components such as the motor part A, the motion conversion mechanism part B, and the casing 20 (housing 2) containing them. It can be easily changed to a specification corresponding to a different use of stroke amount.

  Next, as described above, the actuator head 39 as the operation portion C is provided separately from the screw shaft 33, and the motor assembly A and motion conversion are arranged at the final stage of the assembly process of the electric actuator 1, that is, the inner periphery. After the guide member 10 is connected to the housing 2 in which the mechanism portion B and the like are assembled (see FIG. 8 and the like), the guide member 10 is connected to an end portion on one axial side of the screw shaft 33.

  FIG. 10 is an enlarged view of a main part of the electric actuator 1 shown in FIG. 2 and shows a state in which the connecting operation of the actuator head 39 to the screw shaft 33 is completed. The actuator head 39 is a protrusion fitted to the inner circumference of a recess R (here, one end in the axial direction of the hollow portion of the screw shaft 33) provided at one end in the axial direction of the screw shaft 33. The fitting of the convex portion P with the concave portion R (the fitting between the inner peripheral surface 33b of the screw shaft 33 and the outer peripheral surface 39b of the actuator head 39 opposed thereto) is a so-called clearance fit. . Therefore, the inner peripheral surface 33b of the screw shaft 33 faces the outer peripheral surface 39b of the actuator head 39 via a radial gap δ having a minute gap width, as shown in the enlarged view in FIG. Radial through holes 33c and 39a are respectively formed in one end of the screw shaft 33 in the axial direction and the convex portion P of the actuator head 39, and a solid shaft having a constant diameter is formed in each of the through holes 33c and 39a. A connecting pin 40 made of is inserted. As a result, the screw shaft 33 and the actuator head 39 are engaged in the axial direction within the fitting region of the concave portion R and the convex portion P, and the relative movement and relative rotation in the axial direction of both the portions 33 and 39 are regulated. To be connected.

  Since the connecting pin 40 in the illustrated example is a solid shaft with a constant diameter, there is a possibility that the connecting pin 40 falls off in some time unless any measures are taken. Therefore, in the present embodiment, after the connecting pin 40 is inserted into the through holes 33c and 39a, the caulking portion 33d is formed on the screw shaft 33, thereby preventing the connecting pin 40 from falling off as much as possible. ing.

  Of the screw shaft 33, at least the fitted portion (concave portion R) into which the convex portion P of the actuator head 39 is fitted is an opening (here, in the axial direction of the housing 2 when the motor portion A is stopped). Then, it can project and be accommodated in the outside of the housing 2 via an opening on one side in the axial direction of the guide member 10 connected to the small diameter cylindrical portion 20a of the casing 20. Then, the connecting operation of the actuator head 39 to the screw shaft 33, that is, the fitting of the convex portion P of the actuator head 39 to the concave portion R of the screw shaft 33, the through holes 33c and 39a provided in the screw shaft 33 and the actuator head 39, respectively. As shown in FIG. 10, the insertion of the connecting pin 40 into the pin and the formation of the caulking portion 33 d are performed in a state where the concave portion R of the screw shaft 33 protrudes to the outside of the housing 2.

  In this way, even if the actuator head 39 is connected to the screw shaft 33 at the final stage of the assembly process of the electric actuator 1, the screw shaft 33 ( Including the ball screw device 31), the motor part A, and the housing 2 that accommodates the motor part A or the like, the axial press-fit load does not act. For this reason, it is possible to effectively reduce the possibility that each part of the electric actuator 1 is deformed / damaged as the actuator head 39 is connected to the screw shaft 33, and the operation accuracy of the screw shaft 33 is improved through this. Thus, the electric actuator 1 with high reliability can be realized.

  In addition, the structure which can be taken in order to enjoy such an effect is not restricted to the above. That is, in the above, the screw shaft 33 and the actuator head 39 are connected by using the solid connection pin 40, but instead of such a connection pin 40, for example, a hollow spring pin 41 as shown in FIG. Can also be used. In this case, the spring pin 41 can be prevented from coming off by inserting the spring pin 41 through the through holes 33 c and 39 c and then expanding both ends of the spring pin 41 to engage with the screw shaft 33. .

  Further, the screw shaft 33 and the actuator head 39 are screwed to the screw shaft 33 and the actuator head 39 in place of the shaft-shaped member (the solid connection pin 40 or the hollow spring pin 41) described above. It is also possible to connect them. An example is shown in FIG. In the illustrated example, the convex portion P of the actuator head 39 provided with the male screw portion on the outer peripheral surface is screwed to the concave portion R of the screw shaft 33 provided with the female screw portion on the inner peripheral surface, whereby the screw shaft 33 and The actuator head 39 is engaged with each other in the axial direction, and both are connected. Although not shown in detail, in this case as well, the convex portion P of the actuator head 39 has an outer peripheral surface (the top of the male screw portion) that is the inner peripheral surface of the concave portion R of the screw shaft 33 (of the female screw portion). It faces the bottom part) via a radial gap. Therefore, the configuration shown in FIG. 12 is also included in the scope of the present invention.

  The electric actuator 1 of the present embodiment is combined with the above-described various characteristic configurations, is lightweight and compact, has excellent mountability with respect to the equipment used, has good operation accuracy of the screw shaft 33, and is highly reliable. It has the feature that it is easy to assemble and series.

  Finally, the operation mode of the electric actuator 1 of the present embodiment will be briefly described with reference to FIGS. 1 and 13. For example, when an operation amount is input to an upper ECU (not shown), the ECU calculates a required position command value based on the operation amount. As shown in FIG. 13, the position command value is sent to the controller 81 of the control device 80, which calculates a motor rotation angle control signal necessary for the position command value and sends this control signal to the motor 25.

  When the rotor 24 (rotor inner 26) rotates based on the control signal sent from the controller 81, this rotational motion is transmitted to the motion converting mechanism B, that is, the nut 32 of the ball screw device 31. When the nut 32 rotates in response to the rotational motion of the rotor inner 26, the screw shaft 33 linearly moves (advances) in one axial direction while being prevented from rotating. At this time, the screw shaft 33 moves forward to a position based on the control signal of the controller 81, and the actuator head 39 connected to the end portion on the one axial side of the screw shaft 33 operates an operation target (not shown).

  As shown in FIG. 13, the axial position of the screw shaft 33 (the amount of displacement in the axial direction) is detected by the stroke detection sensor 55, and the detection signal is sent to the comparison unit 82 of the control device 80. Then, the comparison unit 82 calculates the difference between the detection value detected by the stroke detection sensor 55 and the position command value, and the controller 81 is based on the calculated value and the signal sent from the rotation angle detection sensor 53. A control signal is sent to the motor 25. In this way, the position of the actuator head 39 is feedback controlled. For this reason, when the electric actuator 1 of this embodiment is applied to, for example, shift-by-wire, the shift position can be reliably controlled. The electric power for driving the motor 25, the sensors 53, 55, etc. is supplied from an external power source (not shown) such as a battery provided on the vehicle side to a power supply circuit held in the control device 80 and the terminal portion D. Via the motor 25 and the like.

  As mentioned above, although the electric actuator 1 which concerns on one Embodiment of this invention was demonstrated, embodiment of this invention is not restricted to this.

  For example, in the embodiment described above, when the actuator head 39 as the operation unit C is connected to the screw shaft 33, the convex portion provided on the actuator head 39 on the inner periphery of the concave portion R provided on the screw shaft 33. P is fitted (clearance fitting), but conversely, the actuator head 39 is provided with a concave portion R, and the convex portion P provided on the screw shaft 33 is fitted to the inner periphery of the concave portion R. It doesn't matter if you do.

  Further, in the embodiment described above, the compression coil spring 48 that constantly urges the screw shaft 33 toward the origin is provided, but the compression coil spring 48 is provided according to the application that requires the function of urging. If it is not necessary, it may be omitted.

  In the embodiment described above, the rotor inner 26 and the nut 32 disposed on the inner periphery thereof are coupled so as to be able to transmit torque, whereby the rotational motion of the rotor inner 26 (motor unit A) is controlled by the nut 32 (motion conversion mechanism unit). B), but a speed reducer (for example, a planetary gear speed reducer or a planetary roller speed reducer) is provided on the torque transmission path between the rotor inner 26 and the nut 32, and the input side of the speed reducer and the rotor inner 26 are provided. And the output side of the speed reducer and the nut 32 may be connected so as to be able to transmit torque, whereby the rotation of the rotor inner 26 may be decelerated and transmitted to the nut 32. In this case, since the rotational torque of the motor 25 can be increased, the motor 25 can be reduced in size, and the electric actuator 1 can be reduced in weight and size through this.

  In the embodiment described above, the radial gap type motor 25 is adopted, but an axial gap type motor may be adopted. In the embodiment described above, the motion conversion mechanism B is configured by the ball screw device 31, but in the present invention, the ball 34 and the top 35 as a circulation member are omitted from the motion conversion mechanism B. It can also be preferably applied when using a so-called sliding screw.

  In the embodiment described above, the stroke detection sensor 55 is used, but the stroke detection sensor 55 may not be used depending on the device used.

  Based on FIG. 14, an example of the operation mode of the electric actuator 1 when the stroke detection sensor 55 is not used will be described. FIG. 14 is an example of pressure control, and a pressure sensor 83 is provided for an operation target not shown. When an operation amount is input to an ECU (not shown), the ECU calculates a required pressure command value. When this pressure command value is sent to the controller 81 of the control device 80, the controller 81 calculates a motor rotation angle control signal necessary for the pressure command value and sends this control signal to the motor 25. As in the case described with reference to FIG. 13, the screw shaft 33 moves forward to a position based on the control signal of the controller 81, and the actuator head 39 fixed to the end portion on the one axial side of the screw shaft 33 is provided. An operation target not shown is operated.

  The operating pressure of the screw shaft 33 (actuator head 39) is detected by a pressure sensor 83 installed outside and is feedback-controlled. For this reason, when the electric actuator 1 that does not use the stroke detection sensor 55 is applied to, for example, brake-by-wire, the brake hydraulic pressure can be reliably controlled.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

DESCRIPTION OF SYMBOLS 1 Electric actuator 2 Housing | casing 10 Guide member 11 Guide groove 20 Casing 23 Stator 24 Rotor 25 Motor 26 Rotor inner (hollow rotating shaft)
27 Rolling bearing 27a Inner raceway surface 31 Ball screw device 32 Nut 33 Screw shaft 38 Guide collar (rotating body)
39 Actuator head (operation unit)
47 Needle roller bearing A Motor part B Motion conversion mechanism part C Operation part D Terminal part P Convex part R Concave part δ Radial gap

Claims (6)

A motor unit, a motion conversion mechanism unit that converts the rotational motion of the motor unit into a linear motion, an operation unit that receives an output of the motion conversion mechanism unit, and operates an operation target; A screw shaft disposed coaxially with the rotation center of the motor unit, and an outer periphery of the screw shaft. In the electric actuator in which the screw shaft and the operation portion move forward and backward in the axial direction along with the rotation of the nut,
A convex portion provided on the other side of the concave portion provided on one end of the axial direction of the screw shaft and the operating portion is fitted into the other, and the screw shaft and the operating portion are connected to the concave portion and the operating portion. The screw shaft and the operation part are connected by being engaged in the axial direction within the fitting region of the convex part,
The electric actuator characterized in that the concave portion or the convex portion provided on the screw shaft can be projected and housed outside the casing through the opening of the casing when the motor section is stopped. .   The electric actuator according to claim 1, wherein the screw shaft and the operation portion are engaged in an axial direction by a pin inserted through a radial through hole provided in the screw shaft and the operation portion.   The male screw portion provided on the outer peripheral surface of the convex portion is screwed to the female screw portion provided on the inner peripheral surface of the concave portion, whereby the screw shaft and the operation portion are engaged in the axial direction. Item 4. The electric actuator according to Item 1. A rotating body that is rotatable about a radial axis is provided on the screw shaft, and a cylindrical guide member is detachably connected to one axial end of the housing.
The electric actuator according to any one of claims 1 to 3, wherein the guide member has an axial guide groove that fits in such a manner that the rotating body can roll and determines an amount of forward and backward movement of the screw shaft. A hollow rotary shaft that supports the rotor core of the motor unit, and a rolling bearing that rotatably supports the hollow rotary shaft;
The nut is disposed on the inner periphery of the hollow rotary shaft so as to be able to transmit torque with the hollow rotary shaft,
The electric actuator according to claim 1, wherein an inner raceway surface of the rolling bearing is provided on the hollow rotary shaft.   The electric actuator according to claim 5, wherein an inner raceway surface of the rolling bearing is disposed inside an axial width of the nut.

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