JP2019052655A - Electric actuator - Google Patents

Abstract

To provide an electric actuator capable of stably holding the position of a direct-acting member without greatly increasing the number of components.SOLUTION: An electric actuator 1 such that one of a screw shaft 7 and a nut 8 constituting a ball screw 6 is rotated with force from an electric motor 4 and then the other serves as a direct-acting member to let the screw shaft 7 move comprises: a rotation stop groove 5a which restricts the screw shaft 7 from moving around an axial direction; and an engagement pin 7c which is inserted into the rotation stop groove 5a to restrict the screw shaft 7 from moving around the axial direction. The rotation stop groove 5a has a first left inclined surface 5c against which the engagement pin 7c is pressed with axial force applied to the screw shaft 7 and against which the engagement pin 7c is pressed with force around the axial direction which is generated through conversion of the axial force, and when the axial force is applied to the screw shaft 7, the engagement pin 7c is engaged with the first left inclined surface 5c with frictional force to restrict the screw shaft 7 from moving to hold the position.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric actuator provided with a ball screw. Specifically, the present invention relates to an electric actuator having a function of holding the position of a member that moves linearly in a ball screw.

  Conventionally, in general industrial electric motors, automobile transmissions, parking brakes, and the like, an electric actuator provided with a ball screw is used to convert a rotary motion of an output shaft of an electric motor into a linear motion and output it. The electric actuator decelerates the rotational speed of the electric actuator by a gear reduction mechanism or the like and increases the rotational force (torque) for output.

  In such an electric actuator, when an external force in the axial direction is applied to the linear motion member on the output side, it is converted into a force around the axis by a highly efficient ball screw. In the case of an electric actuator, when the electric motor is not outputting torque, or when the force around the axis is greater than the torque of the electric motor, the electric motor is rotated by the force around the axis and the linear motion member is moved by the external force Is done. Thus, an electric actuator is known in which a clutch mechanism is provided between an input-side rotating member and an electric motor. The electric actuator provided with the clutch mechanism is configured such that when an external force is applied to the output side linear motion member and a force around the axis is generated, the clutch mechanism is locked and the linear motion member does not move. For example, as described in Patent Document 1.

  In the electric actuator described in Patent Document 1, an electric motor and a ball screw are arranged side by side on the same axis, and are interlocked and connected via a clutch mechanism. The clutch mechanism includes a cam surface formed on an outer peripheral surface of a rotation driven portion (input side rotation member) on the input shaft side, a roller disposed between the outer ring in which the rotation driven portion is housed, and an electric motor. It is comprised from the nail | claw part formed in the output shaft. In the clutch mechanism, when torque is applied to the rotationally driven part by an external force applied from the output side applied to the screw shaft (output side linear motion member), the roller bites between the outer ring and the rotationally driven part. Is locked and the position of the screw shaft is maintained. However, in the clutch mechanism of the electric actuator described in Patent Document 1, when the torque in one direction applied to the rotation driven portion increases, the amount of biting of the roller between the outer ring and the rotation driven portion increases and is firmly locked. The For this reason, the electric actuator has to be provided with a separate lock release mechanism so that the lock can be released even when a large external force is applied.

JP 2004-150494 A

  The present invention has been made in view of the situation as described above, and can hold the position of the linear motion member without using a force from the electric motor, and the axial direction of the linear motion member is not less than a predetermined value. An object of the present invention is to provide an electric actuator capable of releasing the holding of the position of the linear motion member by applying a force.

  That is, in the electric actuator in which one of the screw shaft and the nut constituting the ball screw is rotated by the force from the electric motor and the other moves as the linear motion member, the linear motion member moves in the direction around the axis. An anti-rotation groove, and an engagement pin that is inserted into the anti-rotation groove and restricts movement of the linear motion member in the axial direction, and the anti-rotation groove has a shaft that is added to the linear motion member. An inclined surface is formed on which the engagement pin is pressed by a force in a direction and the engagement pin is pressed by a force around the shaft generated by converting the axial force, and is axially applied to the linear motion member. When this force is applied, the engagement pin is engaged with the inclined surface by a frictional force, and the movement of the linear motion member is restricted to hold the position.

  The electric actuator includes a sleeve into which the linear movement member is inserted, the rotation preventing groove is formed along the axial direction in the sleeve, and the engagement pin projects in a radial direction from the linear movement member. The inclined surface is formed on the side surface in the detent groove where the engagement pin is pressed by the force in the direction around the axis from the electric motor applied to the linear motion member, with the axial direction as a reference. It is formed at an inclination angle of 10 ° or more and less than 90 °.

  The electric actuator includes a sleeve into which the linear motion member is inserted, the rotation-preventing groove is formed along the axial direction of the linear motion member, and the engagement pin projects in a radial direction from the sleeve. The inclined surface is formed on the side surface in the detent groove where the engagement pin is pressed by the force in the direction around the axis from the electric motor applied to the linear motion member, with the axial direction as a reference. It is formed at an inclination angle of 10 ° or more and less than 90 °.

  In the electric actuator, a plurality of the inclined surfaces are provided on the side surface in the detent groove.

  In the electric actuator, the sleeve is formed by a metal powder injection molding method.

  In the electric actuator, the sleeve includes a main body portion and a groove portion in which the rotation preventing groove is formed, and the groove portion is detachably incorporated in the main body portion.

  As effects of the present invention, the following effects can be obtained.

  That is, in the electric actuator, the frictional force generated between the engagement pin and the inclined surface by the axial force applied to the linear motion member exceeds the component force in the inclined surface direction of the axial force applied to the linear motion member. During this time, the engaging pin is engaged with the inclined surface. That is, in the electric actuator, the position of the linear motion member is held by the frictional force between the engagement pin and the inclined surface. As a result, the position of the linear motion member can be maintained without using the force from the electric motor, and the linear motion member can be held in position by applying an axial force of a predetermined value or more to the linear motion member. It can be canceled.

  In the electric actuator, the engagement pin provided on the linear motion member is pressed against the inclined surface of the rotation stopper groove formed on the sleeve by the axial force applied to the linear motion member. The position of the linear motion member is maintained while the generated frictional force is greater than the component force in the inclined plane direction of the axial force applied to the linear motion member. As a result, the position of the linear motion member can be maintained without using the force from the electric motor, and the linear motion member can be held in position by applying an axial force of a predetermined value or more to the linear motion member. It can be canceled.

  In the electric actuator, the inclined surface of the non-rotating groove formed in the linear motion member is pressed against the engagement pin provided in the sleeve by the axial force applied to the linear motion member. The position of the linear motion member is maintained while the generated frictional force is greater than the component force in the inclined plane direction of the axial force applied to the linear motion member. As a result, the position of the linear motion member can be maintained without using the force from the electric motor, and the linear motion member can be held in position by applying an axial force of a predetermined value or more to the linear motion member. It can be canceled.

  In the electric actuator, the frictional force generated between the inclined surface provided at an arbitrary position of the detent groove and the engaging pin exceeds the component force in the inclined surface direction of the axial force applied to the linear motion member. Meanwhile, the engaging pin is engaged with the inclined surface. That is, in the electric actuator, the holding position of the linear motion member is determined by the position and number of the inclined surfaces provided in the rotation preventing groove. As a result, the position of the linear motion member can be maintained without using the force from the electric motor, and the linear motion member can be held in position by applying an axial force of a predetermined value or more to the linear motion member. It can be canceled.

  The electric actuator is provided with an inclined surface at an arbitrary position, etc., and the sleeve has a non-rotating groove having a complicated shape. However, since a processing method such as sintering with a sintered metal is adopted, the electric actuator The sleeve is easily formed as compared with the case where it is formed only by machining. As a result, the linear motion member can be held at an arbitrary position without using the force from the electric motor, and the position of the linear motion member can be adjusted by applying an axial force equal to or greater than a predetermined value to the linear motion member. Holding can be released.

  In the electric actuator, the holding position and the number of the linear motion members are easily changed by exchanging the groove portion in which the rotation preventing groove is formed. As a result, the linear motion member can be easily held at an arbitrary position without using a force from the electric motor, and an axial force greater than or equal to a predetermined value is applied to the linear motion member. The holding of the position can be released.

Sectional drawing which shows the whole structure in 1st embodiment of an electric actuator. (A) Enlarged cross-sectional view showing a rotation prevention groove of a ball screw in the first embodiment of the electric actuator, (b) A perspective view showing a rotation prevention groove of a sleeve in which the rotation prevention groove is also formed, and a side end view thereof . Sectional drawing which shows the direction of the force of the axial direction which arises in the engagement pin of the ball screw in 1st embodiment of an electric actuator, and the force of the periphery of an axis | shaft. (A) Schematic diagram showing component force of axial force generated on engaging pin of electric actuator, (b) Schematic diagram showing component force of axial force generated on engaging pin, (c) Coefficient The schematic diagram which shows the force of the direction parallel to the direction perpendicular | vertical to the inclined surface which arises in a combined pin. (A) The figure which shows the engagement state of the engagement pin when the force of the left-axis direction from the electric motor in 1st embodiment of an electric actuator is added, and A arrow sectional drawing, (b) Similarly engagement pin The figure which shows an engagement pin engagement state in case the is sliding on the inclined surface of a rotation prevention groove | channel, and B arrow sectional drawing. (A) The figure which shows the engagement state of an engagement pin when the force of the axial direction in 1st embodiment of an electric actuator is added, and C sectional view taken on the arrow, (b) Similarly, an engagement pin is inclination of a rotation prevention groove | channel. The figure which shows the engagement pin engagement state at the time of reaching | attaining a surface, and D arrow sectional drawing. (A) The figure which shows the engagement state of an engagement pin when the force of the right-axis direction from the electric motor in 1st embodiment of an electric actuator is added, and E arrow sectional drawing, (b) Similarly engagement pin The figure which shows an engagement pin engagement state when F reaches | attains the right inclined surface of a rotation prevention groove, and F arrow sectional drawing. (A) Sectional drawing which shows the whole structure in 2nd embodiment of an electric actuator, (b) Sectional drawing which similarly shows a rotation prevention groove | channel. (A) The figure which shows the engagement state of the engagement pin when the force of the axial direction in 2nd embodiment of an electric actuator is added, (b) Similarly, when an engagement pin reaches | attains the inclined surface of a non-rotation groove | channel The figure which shows an engagement pin engagement state. Sectional drawing which shows the whole structure in 3rd embodiment of an electric actuator. (A) Front view and side view showing the second embodiment of the sleeve, (b) Side view showing the main body of the sleeve, (c) Schematic showing the combined state of the groove and main body of the sleeve, (d) ) Similarly, a side view showing a state in which groove portions having different shapes of the non-rotating grooves are combined.

  Below, the electric actuator 1 which is one Embodiment of the electric actuator which concerns on this invention is demonstrated using FIG. 1 and FIG.

  As shown in FIG. 1, the electric actuator 1 converts a rotary motion from an electric power source into a linear motion and outputs the linear motion. The electric actuator 1 includes a storage-side housing 2, an extension-side housing 3, an electric motor 4, a sleeve 5, a ball screw 6 that is a linear motion mechanism, and a gear reduction mechanism 11. The electric actuator 1 is configured to be able to move the screw shaft 7 to an arbitrary position by controlling the movement of the electric motor 4.

  The storage side housing 2 and the extension side housing 3 are main structural members of the electric actuator 1. The storage-side housing 2 and the extension-side housing 3 are fixed integrally with a bolt or the like (not shown) with their side faces butted. The storage-side housing 2 and the extension-side housing 3 are formed from an aluminum alloy such as A6061 or ADC12 or die cast. The storage side housing 2 is formed with a storage portion 2a and a bearing holding portion 2b. The storage part 2a protrudes in the shape of a hollow bottomed cylinder from one side surface of the storage side housing 2 to the other side surface. The storage portion 2a is formed with an inner diameter to which the sleeve 5 can be fitted. The bearing holding portion 2b is configured by an annular recess formed on the same axis as the storage portion 2a in the opening portion of the storage portion 2a. That is, the bearing holding portion 2b is configured by a step portion having an inner diameter larger than the inner diameter of the storage portion 2a. The bearing holding portion 2b is formed to have an inner diameter in which a bearing 10 that rotatably supports the nut 8 of the ball screw 6 can be fitted.

  The aluminum alloy and die cast forming the storage housing 2 and the extension housing 3 are heated to a high temperature to form a solid solution, a quenching process in which it is rapidly cooled in water, and then brought to room temperature. Precipitation hardening treatment is performed in which a large lattice strain is generated in the precipitated phase and hardened by heat treatment constituted by age-hardening treatment (tempering treatment) in which the precipitate is heated or precipitated at a low temperature (100 to 200 ° C.). As a result, the storage-side housing 2 and the extension-side housing 3 can be mass-produced and can be reduced in cost, and at the same time, the strength can be increased and the amount of aluminum used can be reduced to achieve weight reduction. .

  The extension-side housing 3 is formed with an electric motor attachment portion 3a, a gear reduction mechanism arrangement portion 3b, a bearing holding portion 3c, and a communication hole 3d. The electric motor mounting portion 3 a is formed in a circular concave portion on which the electric motor 4 can be mounted on the other side surface of the extending side housing 3. The gear reduction mechanism arrangement portion 3b is formed in a concave shape on one side surface of the extension side housing 3 in which the drive side gear 11a, the driven side gear 11b, and the idle gear 11c constituting the gear reduction mechanism 11 can be arranged. . The bearing holding portion 3 c is configured by an annular concave portion formed on the same axis as the bearing holding portion 2 b of the storage side housing 2, which is one side surface of the extension side housing 3. The bearing holding portion 3c is formed with an inner diameter capable of fitting a bearing 10 that rotatably supports the nut 8 of the ball screw 6. The communication hole 3d is formed on the same axis as the bearing holding portion 3c so as to communicate one side surface and the other side surface of the extending side housing 3.

  The electric motor 4 generates a rotational force. The electric motor 4 is attached to the electric motor attachment portion 3a of the extension side housing 3 so that the output shaft 4a protrudes into the recessed portion of the gear reduction mechanism arrangement portion 3b. The electric motor 4 is configured to be driven at an arbitrary torque, rotation speed, rotation angle, and the like by a control current from a control device (not shown). That is, the electric motor 4 generates a rotational force at a rotational speed and torque according to the control current.

  The sleeve 5 regulates the rotation of the screw shaft 7. The sleeve 5 is formed in a bottomed cylindrical shape. The sleeve 5 is fitted to the storage portion 2 a of the storage side housing 2 and is fixed to the storage side housing 2. On the inner peripheral surface of the sleeve 5, a pair of anti-rotation grooves 5 a that are concave grooves having a predetermined depth extending along the axial direction are formed. The pair of anti-rotation grooves 5a are formed at positions facing each other.

  For example, the sleeve 5 is made of a sintered alloy prepared by adjusting a metal powder into a plastic shape and molding it with an injection molding machine. A pellet in which a binder made of a resin and a wax is mixed with a metal powder is formed by injection molding, and is formed by a sintered metal powder injection molding method (MIM) that is sintered in a sintering furnace. The sleeve 5 is formed in a bottomed cylindrical shape having a non-rotating groove 5a having a complicated shape without going through a plurality of processing steps. Thereby, even if the sleeve 5 has a high degree of processing and a complicated shape, the sleeve 5 is easily and accurately formed into a desired shape and size, so that mass productivity can be improved and cost can be reduced.

  As the metal powder forming the sleeve 5, a material that can be carburized and quenched later, for example, C (carbon) is 0.13 wt%, Ni (nickel) is 0.21 wt%, Cr (chromium) is 1.1 wt%, SCM415 made of 0.04 wt% Cu (copper), 0.76 wt% Mn (manganese), 0.19 wt% Mo (molybdenum), 0.20 wt% Si (silicon), and the rest Fe (iron) or the like. Can be illustrated. The sleeve 5 is performed by adjusting the carburizing quenching and tempering temperatures. In addition, the material of the sleeve 5 includes 3.0 to 10.0 wt% of Ni and has excellent workability and corrosion resistance (FEN8 of Japanese Powder Metallurgy Industry Standard), or C is 0.07 wt%. %, Cr is 17 wt%, Ni is 4 wt%, Cu is 4 wt%, and the remainder is precipitation hardened stainless steel SUS630 made of Fe or the like. This SUS630 can appropriately increase the surface hardness in the range of 20 to 33 HRC by solution heat treatment, and can ensure toughness and high hardness.

  The ball screw 6 converts rotational motion into linear motion. The ball screw 6 includes a screw shaft 7, a nut 8, a plurality of balls 9, and the like.

  The screw shaft 7 which is a linear motion member converts the axial force from the nut 8 into axial force and moves in the axial direction. The screw shaft 7 is disposed over the storage portion 2 a of the storage side housing 2 and the communication hole 3 d of the extension side housing 3 while being rotatably supported by the nut 8. The screw shaft 7 is made of medium carbon steel such as S55C or case-hardened steel such as SCM415 or SCM420, and is subjected to a hardening process of about 55 to 62 HRC by induction hardening or vacuum carburizing and hardening.

  On the outer peripheral surface of the screw shaft 7, a single shaft-side screw groove 7a for rolling the ball 9 is formed. A substantially cylindrical guide portion 7 b is formed at one end of the screw shaft 7. The guide portion 7 b is formed with a diameter that can be inserted into the sleeve 5. The guide portion 7 b is provided with a pair of engagement pins 7 c that protrude in the radial direction at positions facing the rotation stop groove 5 a of the sleeve 5. In the screw shaft 7, the guide portion 7 b is inserted into the sleeve 5, and a pair of engagement pins 7 c are inserted into the rotation stop groove 5 a of the sleeve 5. Thereby, the screw shaft 7 is restricted from moving in the direction around the shaft with respect to the sleeve 5. The other end of the screw shaft 7 is threaded so that a driven component (not shown) can be connected.

  The nut 8 converts the axial force transmitted from the electric motor 4 into an axial force, and moves the screw shaft 7 in the axial direction. The nut 8 is rotatably supported by the bearing holding part 2 b of the storage side housing 2 and the bearing holding part 3 c of the extension side housing 3 via a pair of bearings 10. The nut 8 is formed in a hollow cylindrical shape into which the screw shaft 7 can be inserted. The nut 8 is made of case-hardened steel such as SCM415 or SCM420, and is subjected to a hardening process of about 55 to 62HRC by vacuum carburizing and quenching. On the inner peripheral surface of the nut 8, a one-turn nut-side thread groove 8 a for rolling the ball 9 is formed with the same lead and pitch as the shaft-side thread groove 7 a of the screw shaft 7.

  A piece member 8 b is fitted into a part of the inner peripheral surface of the nut 8. The top member 8b is configured to return the ball 9 to the original shaft-side thread groove 7a even if it climbs over the peak portion (land portion) of the shaft-side thread groove 7a of the screw shaft 7. The screw shaft 7 is inserted into the nut 8 so that the shaft-side screw groove 7a and the nut-side screw groove 8a face each other. A plurality of balls 9 are housed in a space formed by the shaft-side screw groove 7a and the nut-side screw groove 8a so as to be able to roll. That is, the nut 8 supports the screw shaft 7 through a plurality of balls 9 so as to be rotatable around the nut 8 axis. In the present embodiment, the screw shaft 7 is a single thread, but is not limited thereto.

  The pair of bearings 10 support the nut 8. One end of the nut 8 is fitted to the inner ring of one of the pair of bearings 10. The other end of the nut 8 is fitted to the inner ring of the other bearing 10 of the pair of bearings 10. That is, the pair of bearings 10 are provided at both end portions of the nut 8. One bearing 10 is fitted in the bearing holding portion 2 b of the storage-side housing 2. The other bearing 10 is fitted in the bearing holding portion 3 c of the extension side housing 3. That is, the pair of bearings 10 supports the nut 8 so as to be rotatable relative to the storage housing 2 and the extension housing 3.

  The ball screw 6 configured in this manner is supported so that the screw shaft 7 is supported by the nut 8 so as to be relatively rotatable, but is not rotatable relative to the sleeve 5 of the housing 2 in the direction around the shaft. When the nut 8 is rotated, the ball screw 6 transmits a force around the axis to the screw shaft 7 via a plurality of balls 9 accommodated in the shaft-side screw groove 7a and the nut-side screw groove 8a. In the screw shaft 7, the force around the shaft from the nut 8 is converted into the axial force of the screw shaft 7 by the inclination of the shaft-side screw groove 7 a. The screw shaft 7 extends from the storage portion 2 a of the storage side housing 2 through the communication hole 3 d of the extension side housing 3 to the outside of the extension side housing 3 or retracts to the inside of the extension side housing 3.

  The gear reduction mechanism 11 decelerates and outputs the rotational power from the electric motor 4. The gear reduction mechanism 11 includes a driving gear 11a that is a pinion gear, a driven gear 11b that has more teeth than the driving gear 11a, and an idle gear 11c that connects the driving gear 11a and the driven gear 11b. The idle gear 11c is used when the rotational direction of the driven gear 11b is reversed or when the distance between the axes of the driving gear 11a and the driven gear 11b is large. The drive side gear 11a, the driven side gear 11b, and the idle gear 11c are made of sintered metal.

  The drive side gear 11a, the driven side gear 11b, and the idle gear 11c of the gear reduction mechanism 11 are arranged in the gear reduction mechanism arrangement portion 3b of the extension side housing 3 in a meshed state. The drive side gear 11 a is provided so as to be rotatable integrally with the output shaft 4 a of the electric motor 4. A nut 8 is inserted into the driven gear 11b and is provided so as to be integrally rotatable. The idle gear 11 c is rotatably supported by the storage side housing 2 and the extension side housing 3. The idle gear 11c is disposed so as to simultaneously mesh with the drive side gear 11a and the driven side gear 11b. Thereby, the gear reduction mechanism 11 decelerates the input rotational speed from the electric motor 4 according to the reduction ratio between the drive side gear 11a and the driven side gear 11b, and increases and outputs the input torque (rotational force). In the present embodiment, the gear reduction mechanism 11 is constituted by three gears including a driving side gear 11a, a driven side gear 11b, and an idle gear 11c, but is not limited thereto. Moreover, although the drive side gear 11a, the driven side gear 11b, and the idle gear 11c are comprised from the sintered metal, it is not limited to this.

  When the control current based on any one of the torque, the rotation speed, and the rotation angle is supplied to the electric motor 4 from the control device or the like (not shown), the electric actuator 1 configured as described above is supplied with the control current. The output shaft 4a of the electric motor 4 rotates in one direction or the other direction in a corresponding operation mode. The electric actuator 1 converts the input rotation speed and the input torque from the electric motor 4 into an output rotation speed and an output torque corresponding to the reduction ratio of the gear reduction mechanism 11 and transmits them to the ball screw 6. Then, the electric actuator 1 rotates the nut 8 of the ball screw 6 provided with the driven gear 11b to rotate the screw shaft 7 with the speed and the axial force according to the lead of the nut 8 (screw shaft 7). Moves in the axial direction (see black arrow in FIG. 1).

  Below, the structure which hold | maintains the position of the screw shaft 7 which is a linear motion member by the rotation prevention groove | channel 5a of the sleeve 5 (refer FIG. 1) is demonstrated. In the following embodiments, the screw shaft 7 is a right-hand thread. That is, the ball screw 6 is formed by rotating the nut 8 to the left side (hereinafter, simply referred to as “left side”) when viewed from one side (guide portion 7b side) of the screw shaft 7 that is the housing 2 side. 7 is configured to move from the storage-side housing 2 side toward the extension-side housing 3 side (hereinafter simply referred to as “front side in the axial direction”). In addition, the sleeve 5 is provided with two (a pair of) anti-rotation grooves 5a facing each other, but may have a structure in which one anti-rotation groove 5a is formed.

  As shown in FIG. 2, the pair of anti-rotation grooves 5a of the sleeve 5 are provided on the left side in a cross-sectional view perpendicular to the axial direction as viewed from one side (guide portion 7b side) of the screw shaft 7 that is the storage-side housing 2 side. The first left inclined surface 5c and the second left inclined surface 5d are formed at arbitrary positions on the side surface 5b (hereinafter simply referred to as “left side surface 5b”). The left side surface 5b is a side surface on which the engagement pin 7c of the screw shaft 7 is pressed by a force around the left axis transmitted from the nut 8 to the screw shaft 7 in order to move the screw shaft 7 forward in the axial direction. In addition, a right side surface 5e (hereinafter, simply referred to as “right side surface 5e”) of the non-rotating groove 5a in a cross-sectional view perpendicular to the axial direction viewed from one end of the screw shaft 7 is a side surface without a step. Is formed. The right side surface 5e is transmitted from the nut 8 to the screw shaft 7 in order to move the screw shaft 7 from the extending side housing 3 side toward the storage side housing 2 side (hereinafter simply referred to as “axial rear side”). This is the side surface on which the engagement pin 7c is pressed by the force around the right axis.

  The second left inclined surface 5d of the rotation preventing groove 5a is formed on the extending side housing 3 side of the left side surface 5b separated from the first left inclined surface 5c of the rotation preventing groove 5a by an arbitrary length. The width of the non-rotating groove 5a is gradually increased by the first left inclined surface 5c and the second left inclined surface 5d as it goes from the storage side housing 2 side to the extending side housing 3 side. That is, the first left inclined surface 5c and the second left inclined surface 5d are formed as inclined surfaces that are directed forward in the axial direction and around the left axis. An end of the rotation-preventing groove 5a on the storage-side housing 2 side is formed to have a groove width substantially the same as that of the engagement pin 7c of the screw shaft 7.

  Next, the conditions under which the engagement pin 7c of the screw shaft 7 is engaged on the first left inclined surface 5c or the second left inclined surface 5d of the detent groove 5a will be described with reference to FIGS. In the electric actuator 1, the engagement pin 7c of the screw shaft 7 is on the first left inclined surface 5c of the rotation preventing groove 5a, and no torque is generated in the electric motor 4. The first left inclined surface 5 c and the second left inclined surface 5 d are formed on inclined surfaces having an inclination angle θ with respect to the axial direction of the screw shaft 7. For example, the inclination angle θ is set between 10 ° and less than 90 °. It is assumed that a frictional force based on the friction coefficient μ is generated between the first left inclined surface 5c and the second left inclined surface 5d and the engagement pin 7c.

  As shown in FIG. 3, the electric actuator 1 is configured such that when an axial rearward force (see a black arrow) is applied to the screw shaft 7 from the outside, the axial rearward force is applied to the shaft of the screw shaft 7. It is converted by the side thread groove 7a to generate an axial rearward force F1 (see the broken line arrow) and a left-axis-direction force F2 (see the arrow) of the screw shaft 7. The engagement pin 7c of the screw shaft 7 is pressed against the first left inclined surface 5c formed on the left side surface 5b of the detent groove 5a by the axially rearward force F1 and the left axis direction force F2.

As shown in FIG. 4 (a), the engaging pin 7c of the screw shaft 7 has a force F1sin θ in a direction perpendicular to the first left inclined surface 5c of the detent groove 5a, due to the axially rearward force F1. A force F1 cos θ in a direction parallel to the first left inclined surface 5c of the rotation preventing groove 5a is applied.
As shown in FIG. 4B, the engaging pin 7c is parallel to the first left inclined surface 5c and the force F2 cos θ in the direction perpendicular to the first left inclined surface 5c by the force F2 around the left axis. A direction force F2sin θ is applied.
Therefore, as shown in FIG. 4C, the engagement pin 7c has a resultant force F1sinθ + F2cosθ in a direction perpendicular to the first left inclined surface 5c and a resultant force F1cosθ− in a direction parallel to the first left inclined surface 5c. F2sinθ is applied, and a frictional force μ (F1sinθ + F2cosθ) is generated between the first left inclined surface 5c and the engagement pin 7c.

In order for the engaging pin 7c of the screw shaft 7 to be engaged on the first left inclined surface 5c without sliding on the first left inclined surface 5c of the non-rotating groove 5a, as shown in Equation 1 below, The friction force generated between the left inclined surface 5c and the engagement pin 7c may be equal to or greater than the resultant force in the direction parallel to the first left inclined surface 5c. As a result, the engagement pin 7c is engaged on the first left inclined surface 5c under the following conditions from the axially rearward force F1, the leftward-direction force F2, the inclination angle θ, and the friction coefficient μ. 2 is calculated. Further, the condition that the engagement pin 7c slides on the first left inclined surface 5c is the following formula 3 from the axially rearward force F1, the leftward-direction force F2, the inclination angle θ, and the friction coefficient μ. Calculated based on

  When the force F1 to the rear side in the axial direction applied to the engagement pin 7c of the screw shaft 7 increases and the resultant force of the force parallel to the first left inclined surface 5c exceeds the frictional force, the electric actuator 1 7c is moved along the first left inclined surface 5c. As described above, the electric actuator 1 is engaged on the first left inclined surface 5c when the axially rearward force F1 applied to the engagement pin 7c is a value satisfying Equation 2. The position of the screw shaft 7 is held against the axially rearward force F1. On the other hand, in the electric actuator 1, when the axially rearward force F1 increases and reaches a value satisfying Equation 3, the engagement pin 7c is not engaged on the first left inclined surface 5c and the engagement pin 7c is engaged. Slides on the first left inclined surface 5c, the screw shaft 7 moves rearward in the axial direction in accordance with the axially rearward force applied to the screw shaft 7.

  Next, the operation of the ball screw 6 in the electric actuator 1 will be specifically described with reference to FIGS. The electric actuator 1 is in a state in which the engagement pin 7c of the screw shaft 7 is disposed on the left side surface 5b on the rear side (storage side housing 2 side) with respect to the first left inclined surface 5c of the detent groove 5a.

  As shown in FIG. 5A, the ball screw 6 of the electric actuator 1 is screwed via the ball 9 when the nut 8 is rotated about the left axis by the force about the left axis from the electric motor 4. A force in the direction around the left axis is transmitted to the shaft 7 (see the white arrow in the cross-sectional view of the arrow A). The engagement pin 7c of the screw shaft 7 is pressed against the left side surface 5b of the detent groove 5a (see arrow). The screw shaft 7 is restricted from rotating around the left axis by the engagement pin 7c engaging the left side surface 5b. As a result, the screw shaft 7 generates a force on the front side in the axial direction in which the force around the left axis is converted by the shaft-side screw groove 7a. The screw shaft 7 is moved to the front side in the axial direction by the force on the front side in the axial direction (see the black arrow). As a result, the engagement pin 7c slides on the left side surface 5b toward the front side in the axial direction while being pressed against the left side surface 5b (see the broken line arrow).

  As shown in FIG. 5B, when the engagement pin 7c reaches the first left inclined surface 5c of the rotation preventing groove 5a, the screw shaft 7 slides on the first left inclined surface 5c. That is, the screw shaft 7 is rotated in the left-axis direction until the engagement pin 7c reaches the left side surface 5b in the range expanded by the first left inclined surface 5c of the rotation stop groove 5a by the force in the left-axis direction. It moves to the front side in the axial direction while rotating (see the white arrow in the cross-sectional view of arrow B). The screw shaft 7 is restricted from rotating in the direction around the left axis by engaging the engagement pin 7c with the left side surface 5b of the range enlarged by the first left inclined surface 5c. The screw shaft 7 is further moved to the front side in the axial direction by the force on the front side in the axial direction (see the black arrow). As a result, the engagement pin 7c slides on the left side surface 5b toward the front side in the axial direction (see the broken line arrow) while being pressed against the left side surface 5b (see the arrow).

  Similarly, when the engagement pin 7c reaches the second left inclined surface 5d, the screw shaft 7 has a left side surface 5b in a range expanded by the second left inclined surface 5d in the rotation preventing groove 5a by a force in the direction around the left axis. Until the engagement pin 7c arrives, the shaft moves forward in the axial direction while rotating around the left axis. The screw shaft 7 is restricted from rotating around the left axis by engaging the engagement pin 7c with the left side surface 5b of the range enlarged by the first left inclined surface 5c, and further forward in the axial direction by the force in the front direction. Moved. As a result, the engagement pin 7c slides on the left side surface 5b toward the front side in the axial direction while being pressed against the left side surface 5b. In this way, the engagement pin 7c is slid on the first left inclined surface 5c and the second left inclined surface 5d while being pressed against the left side surface 5b of the anti-rotation groove 5a (moves around the left axis). However, it moves toward the front side of the detent groove 5a.

  As shown in FIG. 6 (a), the ball screw 6 of the electric actuator 1 has an axial rearward force applied to the screw shaft 7 from the outside while the force about the left axis from the electric motor 4 is blocked. When applied (see black arrow), the axially rearward force F1 converted by the axially threaded groove 7a and the leftward-direction force F2 (white in the cross-sectional view of the arrow C) Occurs). When the engaging pin 7c of the screw shaft 7 is disposed on the left side surface 5b of the range of the rotation preventing groove 5a of the sleeve 5 that is enlarged by the first left inclined surface 5c, the engaging pin 7c In a state of being pressed against the left side surface 5b by the force F2 around the left axis (see the arrow), the slider slides toward the first left inclined surface 5c by the force F1 toward the rear side in the axial direction (see the broken line arrow).

  As shown in FIG. 6B, when the engagement pin 7c of the screw shaft 7 reaches the first left inclined surface 5c which is a predetermined stop position in the rotation stop groove 5a, the engagement pin 7c is moved to the rear side in the axial direction. At the same time as being pressed against the left inclined surface 5c by the force F1 (see the broken line arrow), it is pressed against the first left inclined surface 5c by the force F2 around the left axis (see the white arrow in the cross-sectional view of the arrow D). When the engagement pin 7c of the screw shaft 7 is disposed on the first left inclined surface 5c which is a predetermined stop position in the rotation stop groove 5a, the engagement pin 7c is perpendicular to the first left inclined surface 5c. A resultant force F1sinθ + F2cosθ in a direction and a resultant force F1cosθ−F2sinθ in a direction parallel to the first left inclined surface 5c are applied, and a frictional force μ (F1sinθ + F2cosθ) is generated between the first left inclined surface 5c and the engaging pin 7c. (See FIG. 4C).

  The engagement pin 7c of the screw shaft 7 is engaged on the first left inclined surface 5c by a frictional force within a range where the axially rearward force F1 satisfies the above-described formula 2. That is, the electric actuator 1 holds the position of the screw shaft 7 against the axially rearward force F1 within a range where the axially rearward force F1 satisfies the above-described formula 2. The engagement pin 7c slides on the first left inclined surface 5c when the axially rearward force F1 increases and is included in the range satisfying the above-described expression 3. In other words, the electric actuator 1 is disengaged when the axially rearward force F1 increases to a range that satisfies the above-mentioned formula 3, and the screw shaft 7 is moved axially rearward according to the axially rearward force F1. Moving.

  As shown in FIG. 7A, the ball screw 6 of the electric actuator 1 is screwed via the ball 9 when the nut 8 is rotated about the right axis by the force about the right axis from the electric motor 4. A force in the direction around the right axis is transmitted to the shaft 7 (see the white arrow in the cross-sectional view of the arrow E). The screw shaft 7 is rotated around the right axis by a force around the right axis by the nut 8. The engagement pin 7c of the screw shaft 7 that has been engaged with the left side surface 5b moves toward the right side surface 5e of the detent groove 5a by the rotation of the screw shaft 7 around the right axis (see the broken line arrow), and the right side It is pressed against the surface 5e. The screw shaft 7 is restricted from rotating by the engagement pin 7c engaging the right side surface 5e.

  As shown in FIG. 7 (b), the transmitted force around the right axis is converted by the shaft-side screw groove 7a to generate a force in the rear side in the axial direction. The screw shaft 7 is moved to the rear side in the axial direction by a force to the rear side in the axial direction. As a result, the engagement pin 7c slides toward the rear side in the axial direction (see the broken line arrow) while being pressed against the right side surface 5e where the inclined surface is not formed (see the arrow).

  With the configuration as described above, the electric actuator 1 can rotate around the sleeve 5 on condition that the above-described Expression 2 is satisfied when the axially rearward force F1 is applied to the screw shaft 7 of the ball screw 6. The engagement pin 7c of the screw shaft 7 is engaged by frictional force on the first left inclined surface 5c or the second left inclined surface 5d formed in the stop groove 5a. In the electric actuator 1, the holding position of the screw shaft 7 is determined by the positions of the first left inclined surface 5c and the second left inclined surface 5d in the rotation preventing groove 5a. That is, in the electric actuator 1, the holding position of the screw shaft 7 of the ball screw 6 and the number of holding positions thereof are determined by the position and the number of the inclined surfaces provided in the anti-rotation groove 5a. Furthermore, in the electric actuator 1, by forming the sleeve 5 by a sintered metal powder injection molding method, the sleeve 5 having the complicated-shaped detent groove 5a in which the inclined surface is provided at an arbitrary position can be easily formed. The Thereby, the electric actuator 1 can hold the position of the screw shaft 7 that is a linear motion member without using the force from the electric motor 4, and the screw shaft 7 is moved rearward in the axial direction by a predetermined value or more. The holding of the position of the screw shaft 7 can be released by applying the force F1.

  Next, the electric actuator 12 which is 2nd embodiment of the electric actuator which concerns on this invention is demonstrated using FIG. The electric actuators according to all of the following embodiments are applied in place of the electric actuator 1 in the electric actuator 1 shown in FIGS. 1 to 5, and the names, figure numbers, and symbols used in the description are used. By using, the same thing is pointed out, In the following embodiment, the specific description is abbreviate | omitted about the point similar to embodiment already demonstrated, and it demonstrates centering on a different part.

  As shown to Fig.8 (a), the electric actuator 12 converts the rotational motion from an electric power source into a linear motion, and outputs it. The electric actuator 12 includes a sleeve 13 and a ball screw 14 that is a linear motion mechanism.

  The sleeve 13 supports an engagement pin 13 a that restricts the rotation of the screw shaft 15. On the inner peripheral surface of the sleeve 13, a pair of engagement pins 13 a are provided at positions facing each other so as to protrude radially inward. The engagement pin 13a is formed to have a diameter that can be inserted into a rotation stop groove 15c of the screw shaft 15 described later.

  The ball screw 14 converts rotational motion into linear motion. The ball screw 14 includes a screw shaft 15, a nut 8, a plurality of balls 9, and the like.

  The screw shaft 15, which is a linear motion member, converts the axial force from the nut 8 into axial force and moves in the axial direction as a linear motion member. The screw shaft 15 has a single shaft-side screw groove 15a for rolling the ball 9 on the outer peripheral surface thereof. A substantially cylindrical guide portion 15 b is formed at one end of the screw shaft 15. The guide portion 15 b is formed to have a diameter that can be inserted into the sleeve 13. The guide portion 15b is formed with a detent groove 15c having a predetermined depth extending along the axial direction. In the screw shaft 15, the guide portion 15 b is inserted into the sleeve 13, and the engagement pin 13 a of the sleeve 13 is inserted into the rotation stop groove 15 c of the screw shaft 15. Thereby, the screw shaft 15 is configured so as not to rotate relative to the sleeve 13 in the direction around the axis.

  As shown in FIG. 8 (b), the anti-rotation groove 15c of the screw shaft 15 has a right side surface 15d (hereinafter simply referred to as “right side” in a cross-sectional view perpendicular to the axial direction as viewed from one end of the screw shaft 15. A first right inclined surface 15e and a second right inclined surface 15f are formed at arbitrary positions (denoted as “surface 15d”). The right side surface 15d is a side surface on which the engagement pin 13a of the sleeve 13 is pressed by the force about the left axis transmitted from the nut 8 to the screw shaft 15 in order to move the screw shaft 15 forward in the axial direction. Further, in the rotation preventing groove 15c, a left side surface 15g (hereinafter, simply referred to as “left side surface 15g”) in a cross-sectional view perpendicular to the axial direction viewed from one end of the screw shaft 15 is a side surface without a step. Is formed. The left side surface 15g is a side surface on which the engagement pin 13a is pressed by a force around the right axis transmitted from the nut 8 to the screw shaft 15 in order to move the screw shaft 15 toward the rear side in the axial direction.

  The second right inclined surface 15f is formed on the rear side in the axial direction (the guide portion 15b side of the screw shaft 15) of the right side surface 15d separated from the first right inclined surface 15e by an arbitrary length. The rotation width of the non-rotating groove 15c is gradually increased by the first right inclined surface 15e and the second right inclined surface 15f as it goes rearward in the axial direction. That is, the first right inclined surface 15e and the second right inclined surface 15f are formed as inclined surfaces that are directed to the rear side in the axial direction and the direction around the right axis. The end of the rotation stop groove 15c on the front side in the axial direction is formed to have substantially the same groove width as the engagement pin 13a of the sleeve 13.

  As shown in FIG. 9 (a), the ball screw 14 of the electric actuator 12 is subjected to an axial rearward force on the screw shaft 15 from the outside in a state where the force around the left axis from the electric motor 4 is interrupted. When applied (see the black arrow), the axially rearward force F1 of the screw shaft 15 converted from the axially rearward force by the shaft-side screw groove 15a and the left-axis-direction force F2 of the screw shaft 15 are applied. Will occur. When the engagement pin 13a of the sleeve 13 is disposed on the right side surface 15d of the range of the rotation preventing groove 15c of the screw shaft 15 expanded by the first right inclined surface 15e, the screw shaft 15 is In a state where the engagement pin 13a is pressed against the right side surface 15d by the force F2 (see arrow), the first right inclined surface 15e is moved in a direction to approach the engagement pin 13a by the axially rearward force F1 (broken line) See arrow).

  As shown in FIG. 9B, when the first right inclined surface 15e reaches the engagement pin 13a, the first right inclined surface 15e is engaged with the engagement pin 13a by friction force. When the engaging pin 13a of the sleeve 13 is disposed on the first right inclined surface 15e which is a predetermined stop position in the rotation stop groove 15c, the first right inclined surface 15e is perpendicular to the first right inclined surface 15e. A resultant force F1sinθ + F2cosθ in a direction and a resultant force F1cosθ−F2sinθ in a direction parallel to the first right inclined surface 15e are applied, and a frictional force μ (F1sinθ + F2cosθ) is generated between the first right inclined surface 15e and the engagement pin 13a. (See FIG. 4C).

  The first right inclined surface 15e formed in the rotation stop groove 15c of the screw shaft 15 is engaged with the engagement pin 13a by a frictional force in a range where the axially rearward force F1 satisfies the above-described formula 2. That is, the electric actuator 12 holds the position of the screw shaft 15 against the axially rearward force F1 in a range where the axially rearward force F1 satisfies the above-described formula 2. The first right inclined surface 15e slides on the engagement pin 13a when the axially rearward force F1 increases and is included in a range that satisfies the above-described Expression 3. In other words, the electric actuator 12 is disengaged when the axially rearward force F1 increases to a range that satisfies the above-mentioned formula 3, and the screw shaft 15 is moved axially rearward according to the axially rearward force F1. Moving.

  By configuring as described above, the electric actuator 12 has the first right inclined surface 15e formed in the anti-rotation groove 15c of the screw shaft 15 by the axially rearward force F1 and the leftward-direction force F2. The second right inclined surface 15f is pressed against the engaging pin 13a of the sleeve 13 by a frictional force. Thereby, the position of the screw shaft 15 that is the linear motion member can be held without using the force from the electric motor 4, and the axial force on the screw shaft 15 toward the rear side in the axial direction is more than a predetermined value. By adding F1, the holding of the position of the screw shaft 15 can be released.

  Next, the electric actuator 16 with a position holding function, which is a third embodiment of the electric actuator according to the present invention, will be described with reference to FIG.

  As shown in FIG. 10, the electric actuator 16 converts the rotary motion from the electric power source into a linear motion and outputs it. The electric actuator 16 includes a one-side housing 17, another side housing 18, a shaft end housing 19, an electric motor 4, a ball screw 20, a sleeve 23, and a gear reduction mechanism 11. The electric actuator 16 with a position holding function is configured to be able to move a nut 22 described later to an arbitrary position by controlling the movement of the electric motor 4.

  A bearing holding portion 17 a is formed in the one side housing 17. The bearing holding portion 17 a is formed on one side surface of the one side housing 17. Moreover, the bearing holding part 17a is formed in the internal diameter which can fit the bearing 10 which supports the screw shaft 21 of the ball screw 20 mentioned later rotatably.

  The other housing 18 is formed with an electric motor mounting portion 18a, a gear reduction mechanism arrangement portion 18b, a bearing holding portion 18c, and a communication hole 18d. The electric motor mounting portion 18 a is formed in a circular recess capable of mounting the electric motor 4 on the other side surface of the other housing 18. The bearing holding portion 18 c is configured by an annular recess formed on one side surface of the other housing 18 and on the same axis as the bearing holding portion 17 a of the one housing 17. The bearing holding portion 18c is formed to have an inner diameter capable of fitting the bearing 10 that rotatably supports the nut 22 of the ball screw 20. The communication hole 18d is formed on the same axis as the bearing holding portion 18c so as to communicate one side surface of the other housing 18 with the other side surface.

  The shaft end housing 19 supports the screw shaft 21 of the ball screw 20. The shaft end housing 19 is fixed to a base (not shown) to which the other housing 18 and the one housing 17 are fixed. The shaft end housing 19 is formed with an inner diameter capable of fitting the bearing 10 that rotatably supports the screw shaft 21.

  The ball screw 20 converts rotational motion into linear motion. The ball screw 20 includes a screw shaft 21, a nut 22, a plurality of balls 9, a bearing 10, and the like.

  The screw shaft 21 converts the axial force transmitted from the electric motor 4 into axial force, and moves the nut 22 in the axial direction. A cylindrical one-side support portion 21 a and another-side support portion 21 b are formed at one end and the other end of the screw shaft 21. Bearings 10 are provided at both end portions of the one side support portion 21a. The bearing 10 is fitted into a bearing holding portion 17 a of the one-side housing 17 and a bearing holding portion 18 c of the other-side housing 18. Similarly, the bearing 10 is provided in the other side support part 21b. The bearing 10 is fitted in the shaft end housing 19. That is, the screw shaft 21 is rotatably supported by the one side housing 17, the other side housing 18, and the shaft end housing 19 through the bearing 10 of the one side support portion 21a and the bearing 10 of the other side support portion 21b. .

  The nut 22 which is a linear motion member converts a force around the axis from the screw shaft 21 into an axial force and moves in the axial direction as a linear motion member. The nut 22 is disposed between the shaft end housing 19 and the other housing 18 while being supported rotatably around the axis of the screw shaft 21 via the plurality of balls 9. The nut 22 has a diameter that can be inserted into the sleeve 23. Further, the nut 22 is formed with a pair of engaging pins 22a protruding in the radial direction at positions opposed to the pair of detent grooves 23a of the sleeve 23.

  The sleeve 23 regulates the rotation of the nut 22. The sleeve 23 is fixed to a base (not shown) to which the one side housing 17 and the other side housing 18 are fixed. That is, the sleeve 23 is configured to restrict rotation with respect to the nut 22. The sleeve 23 is formed to have a diameter into which the nut 22 can be inserted. A pair of detent grooves 23 a extending in the axial direction is formed on the inner peripheral surface of the sleeve 23 at a position facing the engaging pin 22 a of the nut 22. The anti-rotation groove 23a is formed in a width that allows the engagement pin 22a to be inserted. In the rotation preventing groove 23a, a first left inclined surface 23c and a second left inclined surface 23d are formed on the left side surface 23b.

  In the ball screw 20 configured as described above, the screw shaft 21 is rotatably supported by the one-side housing 17, the other-side housing 18, and the shaft-end housing 19 via the bearing 10. The ball screw 20 is slidably inserted into a sleeve 23 in which a nut 22 is integrally fixed to a base (not shown). At this time, the engagement pin 22 a of the nut 22 is slidably engaged with the rotation prevention groove 23 a of the sleeve 23. That is, the nut 22 is inserted into the screw shaft 21 so as not to be relatively rotatable in the direction around the axis of the sleeve 23 while being rotatably supported in the direction around the axis. When the screw shaft 21 is rotated, the ball screw 20 transmits a force in the direction around the shaft to the nut 22. Since the nut 22 is inserted so as not to be relatively rotatable in the direction around the axis of the sleeve 23, the force around the axis from the screw shaft 21 is converted into the force in the axial direction of the screw shaft 21. The nut 22 reciprocates in the axial direction on the screw shaft 21 while being inserted into the sleeve 23.

  The drive side gear 11a, the driven side gear 11b, and the idle gear 11c are arranged in a gear reduction mechanism arrangement portion 18b of the other side housing 18 in a meshed state. The driven gear 11b is provided so that the one-side support portion 21a of the screw shaft 21 is inserted into a support shaft insertion hole formed at the center thereof so as to be integrally rotatable.

  In the electric actuator 16 configured in this manner, the nut 22 is rotated at a speed and axial thrust according to the lead of the screw shaft 21 by rotating the screw shaft 21 of the ball screw 20 provided with the driven gear 11b. It moves linearly in the axial direction (see black arrow in FIG. 10).

  With the configuration as described above, the electric actuator 16 has the first left inclined surface 23c and the second inclined surface 23c formed in the rotation-preventing groove 23a when the axially rearward force F1 is applied to the nut 22 of the ball screw 20 from the outside. The engaging pin 22a of the nut 22 is engaged with the left inclined surface 23d. As a result, the position of the nut 22 that is the linear motion member can be held without using the force from the electric motor 4, and the axially rearward force F1 of a predetermined value or more is applied to the nut 22. The holding of the position of the nut 22 can be released.

  As shown in FIG. 11, the sleeve 5 in the first embodiment and the sleeve 23 in the third embodiment are integrally formed from metal powder by a sintered metal powder injection molding method. Alternatively, the sleeve 24 may be a separate part.

As shown in FIG. 11A, the sleeve 24 includes a main body portion 24a and a groove portion 24c (a dark thin ink portion).
As shown in FIG. 11B, the main body portion 24 a is a main structure of the sleeve 24. The main body 24a is formed in a cylindrical shape. On the side surface of the main body 24a, a notch 24b is formed in an opposing portion.
As shown in FIG. 11 (c), the groove 24 c is a recombination portion of the sleeve 24. The groove 24c is formed with a detent groove 24d. The groove portion 24c is configured to be detachably incorporated in the notch 24b of the main body portion 24a.
As shown in FIG. 11 (d), the sleeve 24 configured in this manner is replaced with a groove portion 24e in which a rotation prevention groove 24f (thin thin ink portion) having a different shape is formed, thereby holding the linear movement member. And the number is changed. Thereby, the screw shafts 7 and 15 and the nuts 22 which are linear motion members can be easily held at arbitrary positions without using the force from the electric motor 4, and the screw shafts 7 and 15 and the nuts 22 are The holding of the positions of the screw shafts 7 and 15 and the nut 22 can be released by applying an axial force of a predetermined value or more.

  In the first to third embodiments, the anti-rotation grooves 5a, 15c, and 23a are formed with two inclined surfaces, but it is sufficient that at least one or more inclined surfaces are formed. Further, the sleeve 5 in the first embodiment and the sleeve 23 in the third embodiment are formed into a cylindrical shape by cold forging from medium carbon steel such as S55C or case-hardened steel such as SCM415 or SCM420, and induction hardening, or It may be formed by carburizing and quenching the surface thereof in a range of 55 to 62 HRC.

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

DESCRIPTION OF SYMBOLS 1 Electric actuator 4 Electric motor 5 Sleeve 5a Non-rotating groove 5c 1st left inclined surface 6 Ball screw 7 Screw shaft 7c Engagement pin 8 Nut

Claims (6)

In the electric actuator in which one of the screw shaft and nut constituting the ball screw is rotated by the force from the electric motor and the other is moved as a linear motion member.
A non-rotating groove for restricting movement of the linear member in the direction around the axis;
An engagement pin that is inserted into the non-rotating groove and restricts movement of the linear motion member in the axial direction,
The engagement pin is pressed against the rotation-preventing groove by an axial force applied to the linearly moving member, and the engagement pin is pressed by an axial rotation force generated by converting the axial force. An inclined surface to be pressed is formed,
When an axial force is applied to the linear motion member, the electric actuator is engaged with the inclined surface by a frictional force to restrict the movement of the linear motion member and hold the position. A sleeve into which the linear motion member is inserted;
The anti-rotation groove is formed along the axial direction in the sleeve;
The engagement pin is provided so as to protrude in a radial direction from the linear motion member;
The inclined surface is 10 ° or more and less than 90 ° on the basis of the axial direction on the side surface in the non-rotating groove on which the engagement pin is pressed by the force around the shaft from the electric motor applied to the linear motion member. The electric actuator according to claim 1, wherein the electric actuator is formed at an inclination angle of. A sleeve into which the linear motion member is inserted;
The non-rotating groove is formed along the axial direction in the linear motion member;
The engagement pin is provided so as to protrude radially from the sleeve;
The inclined surface is 10 ° or more and less than 90 ° on the basis of the axial direction on the side surface in the non-rotating groove on which the engagement pin is pressed by the force around the shaft from the electric motor applied to the linear motion member. The electric actuator according to claim 1, wherein the electric actuator is formed at an inclination angle of.   The electric actuator according to any one of claims 1 to 3, wherein a plurality of the inclined surfaces are provided on a side surface in the detent groove.   The electric actuator according to any one of claims 1 to 4, wherein the sleeve is formed by a metal powder injection molding method.   The said sleeve is comprised from the main-body part and the groove part in which the said rotation prevention groove | channel is formed, The said groove part is integrated in the said main-body part so that attachment or detachment is possible. Electric actuator.

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