JP2017096313A - Electric actuator with position holding function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric actuator with a position holding function which can easily release the holding of a position while stably holding the position of a linear motion member.SOLUTION: An electric actuator 1 with a position holding function which transmits a rotation force from an electric motor 4 to a ball screw 6 comprises: one-side whirl stop grooves 5a for regulating the rotation of a screw shaft 7 around an axis; other-side whirl stop grooves 5g for regulating the rotation of the screw shaft 7 around the axis which is moved toward one side from the other side of the ball screw 6 by a rotation force from the electric motor 4; and a pin 7c which can be engaged with the one-side whirl stop grooves 5a and the other-side whirl stop grooves 5g. A first left step 5c and a second left step 5d for regulating the movement of the screw shaft 7 to an axial direction by an external force are formed at each of a plurality of the one-side whirl stop grooves 5a and a plurality of the other-side whirl stop grooves 5g, and the pin 7 is movable between the one-side whirl stop grooves 5a and the other-side whirl stop grooves 5g.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 with a position holding function provided with a ball screw having a position holding function.

  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 for output. Such an electric actuator converts the external force into a rotational force by a highly efficient ball screw mechanism when an external force in the axial direction is applied to the linear motion member on the output side. The external force converted into the rotational force is transmitted to the electric motor via the input side rotating member. In the electric actuator, when the electric motor does not output a rotational force or when an external force larger than the rotational force of the electric motor is transmitted to the electric motor, the electric motor is rotated by the external force and the linear motion member moves. 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 rotational force 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 a rotational force is applied to the rotationally driven portion by an external force applied to the screw shaft (output-side linear motion member), a roller bites between the outer ring and the rotationally driven portion. The part is locked. As a result, the electric actuator is prevented from rotating by the external force from the output side, and the position of the screw shaft is maintained. However, the technique described in Patent Document 1 is proportional to the magnitude of the external force applied to the rotating driven part by the frictional force generated between the outer ring and the rotating driven part. For this reason, the electric actuator is disadvantageous in that the rotational force necessary for unlocking increases as the external force increases.

JP 2004-150494 A

  The present invention has been made in view of the above situation, and an object thereof is to provide an electric actuator with a position holding function that can easily release the position holding while stably holding the position of the linear motion member. To do.

  That is, in the electric actuator with a position holding function for transmitting the rotational force from the electric motor to the ball screw, one of the screw shafts and the nuts constituting the ball screw is changed from one side of the ball screw by the rotational force from the electric motor. A one-side detent groove for restricting rotation around the axis of the linear motion member moved toward the side, and the linear motion moved toward the one side from the other side of the ball screw by the rotational force from the electric motor A plurality of the one-side detent grooves or a plurality of one-side detent grooves, and a pin that can be engaged with the one-side detent groove and the other-side detent groove. A step for restricting the axial movement of the linear motion member due to an external force is formed in the other-side detent groove of the pin, so that the pin can move between the one-side detent groove and the other-side detent groove. It is configured Than is.

  The linear motion member includes a sleeve into which the linear motion member is slidably inserted, and a plurality of the one-side detent grooves and a plurality of the other-side detent grooves formed along the axial direction of the linear motion member are the Provided alternately in the circumferential direction of the sliding surface of the sleeve, the pin is provided on the sliding surface of the linear motion member, and the step is a side surface of the plurality of one-side detent grooves or a plurality of the other side It is provided on the side surface of the non-rotating groove so as to dent the side surface against which the pin is pressed by a rotational force generated by an external force applied in the axial direction to the linear motion member. Of the plurality of other-side detent grooves, a terminal end side of the groove provided with the step and a start end side of the groove provided adjacent to the side surface provided with the step are connected, A start end side of the groove provided with the step, and the step In which is the terminal end of the groove provided on the side surface side of the side surface facing provided is connected.

  The linear motion member includes a sleeve into which the linear motion member is slidably inserted, and a plurality of the one-side detent grooves and a plurality of the other-side detent grooves formed along the axial direction of the linear motion member are the The sliding surface of the linear motion member is alternately provided along the axial direction, the pin is provided on the sliding surface of the sleeve, and the step is a side surface of the plurality of one-side detent grooves or the plurality of the other side. It is provided on the side surface of the non-rotating groove so as to dent the side surface against which the pin is pressed by a rotational force generated by an external force applied in the axial direction to the linear motion member. Of the plurality of other-side detent grooves, a terminal end side of the groove provided with the step and a start end side of the groove provided adjacent to the side surface provided with the step are connected, A start end side of the groove provided with the step, and the step In which is the terminal end of the groove provided on the side surface side of the side surface facing provided is connected.

  The step is a side surface of the plurality of one-side detent grooves or a side surface of the plurality of the other-side detent grooves, and the side surface on which the pin is pressed by a rotational force generated by an external force applied to the linear motion member. A plurality are provided at arbitrary positions.

  A plurality of the pins are arranged along the circumferential direction of the linear motion member or the sleeve.

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

  That is, in the electric actuator with a position holding function, the movement by the external force of the linear motion member is restricted by the engagement between the step and the pin by the position holding structure configured by using the structure of the rotation stopper. Further, the pin is moved without engaging the step by the groove not provided with the step. Thereby, position holding | maintenance can be cancelled | released easily, hold | maintaining the position of a linear motion member stably.

  In the electric actuator with a position holding function, the pin is continuously moved between the groove in which the step is provided and the groove in which the step is not provided by the axial movement and the rotation around the axis of the linear motion member. Thereby, position holding | maintenance can be cancelled | released easily, hold | maintaining the position of a linear motion member stably.

  In the electric actuator with a position holding function, the position holding mode of the linear motion member is determined by the number of steps and the position thereof. Thereby, position holding | maintenance can be cancelled | released easily, hold | maintaining the position of a linear motion member stably.

  In the electric actuator with a position holding function, backlash between the one-side detent groove or the other-side detent groove and the pin is suppressed. Thereby, position holding | maintenance can be cancelled | released easily, hold | maintaining the position of a linear motion member stably.

Sectional drawing which shows the whole structure in 1st embodiment of the electric actuator with a position holding function. (A) The enlarged view which shows the position holding structure of the ball screw in 1st embodiment of the electric actuator with a position holding function. (B) The partial cross section perspective view and the one side end view of the sleeve in which the same position holding structure is formed. The figure which shows the expanded view seen from the outer peripheral surface side of the sleeve in 1st embodiment of the electric actuator with a position holding function. (A) The figure which shows the operation | movement aspect of a ball screw by the rotational force of the one direction from the electric motor in 1st embodiment of the electric actuator with a position holding function, and A sectional view taken on the arrow (b) When a screw shaft moves similarly The figure which shows the operation | movement aspect of the pin which passed the level | step difference, and B arrow sectional drawing. (A) The figure which shows the aspect by which the position of the ball screw to which the external force of one direction was added in 1st embodiment of the electric actuator with a position holding function was hold | maintained, and C sectional view taken on the arrow (b) The figure which shows the state which the axis | shaft moved and passed the groove | channel for a movement, and D arrow sectional drawing. (A) The figure which shows the aspect which the screw shaft is retracted by the rotational force of the other direction from the electric motor in 1st embodiment of the electric actuator with a position holding function, and E sectional drawing (b) Same direction rotation The figure which shows the operation | movement aspect which starts a screw shaft to move to an extending | stretching direction with force, and F arrow sectional drawing. (A) The figure which shows the expanded view seen from the outer peripheral surface side of the sleeve in 2nd embodiment of the electric actuator with a position holding function. (B) The axial direction side view which similarly shows the structure of the pin provided in the screw shaft. The figure which shows the expanded view seen from the outer peripheral surface side of the sleeve in 3rd embodiment of the electric actuator with a position holding function. (A) Sectional drawing which shows the engagement state of the pin and one side rotation prevention groove in 4th embodiment of the electric actuator with a position holding function (b) One side rotation prevention groove and other side rotation similarly formed in the screw shaft Sectional drawing which shows the structure of a stop groove. Sectional drawing which shows the whole structure in 5th embodiment of the electric actuator with a position holding function. The fragmentary sectional view which shows the structure of the 1st side non-rotation groove | channel formed in the sleeve in 5th embodiment of the electric actuator with a position holding function, and the other side rotation prevention groove | channel.

  Below, the electric actuator 1 with a position holding function which is 1st embodiment of the electric actuator with a position holding function which concerns on this invention using FIG. 1 and FIG. 2 is demonstrated.

  As shown in FIG. 1, the electric actuator 1 with a position holding function converts a rotary motion from an electric power source into a linear motion and outputs the linear motion. The electric actuator 1 with a position holding function includes a storage-side housing 2, an extension-side housing 3, an electric motor 4, a sleeve 5, a ball screw 6 (arrow position in FIG. 1) that is a linear motion mechanism, and a gear reduction mechanism 11. The electric actuator 1 with a position holding function 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 with a position holding function. 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 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 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 is formed with a storage portion 2a and a ball bearing holding portion 2b. The storage portion 2 a is formed in a hollow bottomed cylindrical shape capable of storing a screw shaft 7 of a ball screw 6 described later on the other side surface of the storage-side housing 2. The storage portion 2a is integrally provided with a sleeve 5 fitted therein. The ball bearing holding portion 2 b is formed in the opening portion of the storage portion 2 a that is on the same axis as the storage portion 2 a and is one side surface of the storage side housing 2. The ball bearing holding portion 2b is formed so as to hold a ball bearing 10 that rotatably supports a nut 8 of a ball screw 6 to be described later.

  The extension-side housing 3 is formed with an electric motor attachment portion 3a, a gear reduction mechanism arrangement portion 3b, a ball bearing holding portion 3c, and a communication hole 3d. The electric motor attachment portion 3 a is formed in a shape that allows the electric motor 4 to be attached to 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 ball bearing holding portion 3 c is formed on one side surface of the extension side housing 3 and on the same axis as the ball bearing holding portion 2 b of the storage side housing 2. The ball bearing holding portion 3c is formed so as to hold a ball bearing 10 that rotatably supports a nut 8 of the ball screw 6. The communication hole 3d is formed on the same axis as that of the ball bearing holding portion 3c so as to communicate one side surface and the other side surface of the extending side housing 3. That is, the communication hole 3 d communicates the inside of the storage portion 2 a of the storage side housing 2 with the outside.

  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 cylindrical shape by cold forging from medium carbon steel such as S55C or case-hardened steel such as SCM415 or SCM420, and the surface thereof is hardened in a range of 55 to 62 HRC by induction hardening or carburizing quenching. It has been subjected. Thereby, mass productivity improves and it can aim at low cost. The sleeve 5 is provided integrally with the storage portion 2 a of the storage-side housing 2. That is, the sleeve 5 is configured so as not to rotate relative to the storage-side housing 2. On the inner peripheral surface of the sleeve 5, two one-side anti-rotation grooves 5a and two other-side anti-rotation grooves 5g that are concave grooves extending along the axial direction are alternately arranged in the circumferential direction. Provided (see FIG. 2). The one-side detent groove 5a and the other-side detent groove 5g constitute a detent portion.

  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, a ball bearing 10, and the like.

  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. The screw shaft 7 has a plurality of one-side shaft-side thread grooves 7a for rolling the ball 9 on the outer peripheral surface thereof. A substantially cylindrical sliding portion (not required to slide) 7 b is formed at one end of the screw shaft 7 that is one side of the ball screw 6. The sliding portion 7b is formed to have a diameter that can be slidably inserted into the sleeve 5. The sliding portion 7b is provided with a pin 7c projecting in the radial direction at a position facing the two one-side detent grooves 5a or the two other-side detent grooves 5g of the sleeve 5. The two pins 7c may be configured such that one pin protrudes on both sides of the sliding portion 7b so as to pass through the axis of the screw shaft 7. The two pins 7c are formed to have a diameter capable of sliding the one-side detent groove 5a, the other-side detent groove 5g, the one-side movement groove 5j, and the other-side movement groove 5f of the sleeve 5. The two pins 7c constitute a detent portion. The other end of the screw shaft 7, which is the other side of the ball screw 6, is threaded or the like to which a driven object (not shown) can be connected.

  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. A nut-side thread groove 8 a for rolling the ball 9 is formed on the inner peripheral surface of the nut 8 with the same lead and pitch as the shaft-side thread groove 7 a of the screw shaft 7. Further, 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. On the outer peripheral surface of the nut 8, a flange portion 8 c that is a stepped portion whose outer diameter is partially enlarged is formed. 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. Further, ball bearings 10 are provided at both end portions of the nut 8. In addition, in this embodiment, although the shaft side thread groove 7a of the screw shaft 7 was 1 turn, it is not limited to this.

  In the ball screw 6 configured in this way, one ball bearing 10 provided on the nut 8 is held by the ball bearing holding portion 2 b of the storage side housing 2, and the other ball bearing 10 is connected to the extension side housing 3. It is held by the ball bearing holding portion 3c. That is, the nut 8 is rotatably supported by the storage side housing 2 and the extension side housing 3 via the ball bearing 10. The ball screw 6 has a screw shaft 7 disposed in the storage portion 2 a of the storage-side housing 2 and the communication hole 3 d of the extension-side housing 3. A sliding portion 7b of the screw shaft 7 on one side of the ball screw 6 is slidably inserted into the sleeve 5 of the storage portion 2a. The other side end of the screw shaft 7, which is the other side of the ball screw 6, is disposed in the communication hole 3 d of the extension side housing 3. At this time, in the screw shaft 7, the two pins 7 c of the sliding portion 7 b are slidably engaged with the two one-side anti-rotation grooves 5 a or the two other anti-rotation grooves 5 g of the sleeve 5. As described above, the ball screw 6 has a detent portion formed by the two pins 7c of the sliding portion 7b of the screw shaft 7 and the two one-side detent grooves 5a or the two other detent grooves 5g of the sleeve 5. Has been. That is, the screw shaft 7 is supported by the nut 8 so as to be rotatable around the shaft, and the sleeve 5 is formed by engagement between the two one-side detent grooves 5a or the two other-side detent grooves 5g and the two pins 7c. It is inserted so that it cannot rotate relative to.

  When the nut 8 is rotated, the rotational force of the ball screw 6 is transmitted to the screw shaft 7 through a plurality of balls 9 accommodated in the shaft-side screw groove 7a and the nut-side screw groove 8a. When two pins 7c are engaged with two one-side anti-rotation grooves 5a or two other anti-rotation grooves 5g, the rotational movement of the nut 8 is caused by the inclination of the shaft-side screw groove 7a. It is converted into a linear motion in the axial direction of the shaft 7. In this way, the screw shaft 7 of the ball screw 6 passes from the storage portion 2a of the storage side housing 2 through the communication hole 3d of the extension side housing 3 to the outside from the extension side housing 3 which is the other direction of the ball screw 6. It extends toward or retracts toward the inside which is one side direction of the ball screw 6.

  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 are arranged in the gear reduction mechanism arrangement portion 3b of the extension side housing 3 in an engaged 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 mesh with the driving side gear 11a and the driven side gear 11b simultaneously. 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.

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

  Hereinafter, the one-side detent groove 5a and the other-side detent groove 5g constituting the detent portion of the ball screw 6 (see FIG. 1) will be described in detail with reference to FIGS. In the present embodiment, the shaft-side thread groove 7a formed in the screw shaft 7 is a right-hand thread, but is not limited thereto. Further, the sleeve 5 is provided with two one-side anti-rotation grooves 5a and two other-side anti-rotation grooves 5g. However, the present invention is not limited to this, and the one-side anti-rotation groove 5a and the other side are provided. A configuration in which one or three or more anti-rotation grooves 5g are formed may be used (see FIG. 7). The ball screw 6 has an anti-rotation portion in which the sleeve 5 is provided with two one-side anti-rotation grooves 5a and two other anti-rotation grooves 5g, and the screw shaft 7 is provided with two pins 7c. The screw shaft may be provided with a one-side detent groove and another-side detent groove, and the sleeve 5 may be provided with a pin (see FIG. 9).

  As shown in FIG. 2, the two one-side detent grooves 5a and the two other-side detent grooves 5g of the sleeve 5 engage the two pins 7c of the screw shaft 7 that is a linear motion member. The two one-side detent grooves 5a and the two other-side detent grooves 5g are formed on the inner peripheral surface of the sleeve 5 so as to extend along the axis. The two one-side anti-rotation grooves 5a and the two other-side anti-rotation grooves 5g are counterclockwise along the circumferential direction in a cross-sectional view perpendicular to the axial direction when viewed from one side of the sleeve 5 (hereinafter simply referred to as “left 1 side detent groove 5a, one other side detent groove 5g, the other one side detent groove 5a, and the other other side detent groove 5g are alternately arranged in this order. ing. At this time, the two one-side anti-rotation grooves 5a and the two other anti-rotation grooves 5g are arranged so that the one-side anti-rotation grooves 5a face each other and the other-side anti-rotation grooves 5g face each other. Has been.

  As shown in FIG. 3, the two one-side detent grooves 5a (dark shaded portions) are formed from one end of the sleeve 5 arranged in the direction of one side of the ball screw 6 (retreat side of the screw shaft 7). It is formed toward the other end of the sleeve 5 arranged in the direction of the other side of the ball screw 6 (the extending side of the screw shaft 7). That is, the two one-side anti-rotation grooves 5a are formed as concave grooves starting from one end of the sleeve 5 and ending at the other end of the sleeve 5.

  The two one-side detent grooves 5a have a left side surface 5b (hereinafter, simply referred to as “left side surface 5b”) in a cross-sectional view perpendicular to the axial direction as viewed from one end side of the sleeve 5 which is one side of the ball screw 6. The first left step 5c and the second left step 5d, which are position holding structures, are formed at arbitrary positions. The second left step 5d is formed on the left side surface 5b on the extending side housing 3 side which is separated from the first left step 5c by an arbitrary length. The width of the two one-side detent grooves 5a is increased by the first left step 5c and the second left step 5d from one side end of the sleeve 5 that is the starting end toward the other end of the sleeve 5 that is the end. It is expanding gradually. That is, the first left step 5c and the second left step 5d are formed such that their step surfaces (engagement surfaces of the pins 7c of the screw shaft 7) face the terminal side of the one-side detent groove 5a. . The first left step 5c and the second left step 5d are formed in the shape of a step surface with which the pin 7c can be engaged. Specifically, when the pin 7c is a cylinder, the first left step 5c and the second left step 5d are formed with a step amount larger than the radius of the pin 7c. Further, in the one-side detent groove 5a, the right side surface 5e (hereinafter simply referred to as “right side surface 5e”) in a cross-sectional view perpendicular to the axial direction viewed from one end side of the sleeve 5 has no step. It is formed on the side. In the present embodiment, a plurality of steps are formed in the one-side detent groove 5a. However, the present invention is not limited to this, and one step or three or more steps may be provided.

  The two other-side detent grooves 5g (thin shaded portions) are formed on one side (screw) of the ball screw 6 from the other end of the sleeve 5 disposed on the other side of the ball screw 6 (the extending side of the screw shaft 7). It is formed toward one end of the sleeve 5 disposed on the retreat side of the shaft 7. That is, the two other anti-rotation grooves 5g are formed as concave grooves starting from the other end of the sleeve 5 and ending at one end of the sleeve 5. The left side surface 5h and the right side surface 5i of the two other-side detent grooves 5g are formed on side surfaces having no step.

  One end of the one-side detent groove 5a (the extension side of the screw shaft 7) is the starting end of one other-side detent groove 5g provided adjacent to the left side surface 5b of the one-side detent groove 5a ( The other side moving groove 5f is connected to the extending side of the screw shaft 7). The other-side moving groove 5f is formed at the other end of the sleeve 5 so as to extend counterclockwise along the circumferential direction on the inner peripheral surface of the sleeve 5. That is, the terminal end of one one-side detent groove 5a is connected to the start end of one other-side detent groove 5g provided on the left side via the other-side moving groove 5f. Further, the other end of the other side detent groove 5g (retreat side of the screw shaft 7) is adjacent to the left side of the other side detent groove 5g. Is connected to the starting end (retreat side of the screw shaft 7) via a one-side moving groove 5j. The one-side moving groove 5j is formed at one end of the sleeve 5 so as to extend counterclockwise along the circumferential direction on the inner peripheral surface of the sleeve 5. That is, the terminal end of one other-side detent groove 5g is connected to the start end of the other one-side detent groove 5a provided on the left side.

  Similarly, the terminal end of the other one-side detent groove 5a is connected to the start end of the other other-side detent groove 5g provided on the left side via the other-side moving groove 5f. The other end of the other anti-rotation groove 5g is connected to the starting end of one of the one anti-rotation grooves 5a provided on the left side via the one-side moving groove 5j. Thus, the two one-side anti-rotation grooves 5a and the two other anti-rotation grooves 5g arranged alternately along the circumferential direction on the inner peripheral surface of the sleeve 5 are the one-side movement groove 5j and the other. The side moving grooves 5f are alternately connected to each other, and are configured as a single groove that goes around the inner peripheral surface of the sleeve 5. Two pins 7c provided on the sliding portion 7b of the screw shaft 7 are inserted into the two one-side detent grooves 5a or the two other-side detent grooves 5g, respectively.

  Next, using FIG. 3 to FIG. 5, two one-side detent grooves 5 a (hereinafter simply referred to as “one-side detent grooves 5 a”) constituting the detent portions, and two other-side detent grooves 5 g ( Hereinafter, a description will be given of how the position is held by simply “the other-side detent groove 5 g” and the two pins 7 c of the screw shaft 7 (hereinafter, simply referred to as “pin 7 c”). It is assumed that the screw shaft 7 of the ball screw 6 is in a state of being retracted to one side (storage side housing 2 side). At this time, the pin 7c is engaged with the one-side detent groove 5a. In the present embodiment, the first left step 5c and the second left step 5d, which are position holding structures, are provided in the one-side detent groove 5a, but are not limited to this, and the other-side detent groove is provided. You may provide in 5g.

  As shown in FIG. 4A, when the nut 8 is rotated counterclockwise by the rotational force from the electric motor 4 in order to extend the screw shaft 7, the ball screw 6 has an axial thread groove 7a. Counterclockwise, a counterclockwise rotational force is generated (see the white arrow in the cross-sectional view of arrow A). The pin 7c of the screw shaft 7 about to rotate counterclockwise is engaged with the left side surface 5b of the one-side detent groove 5a of the sleeve 5 (one one-side detent groove 5a). In the ball screw 6, the rotation of the screw shaft 7 is restricted by engaging the left side surface 5b of the one-side detent groove 5a with the pin 7c. The screw shaft 7 is moved in the direction of the other side of the ball screw 6 by converting the counterclockwise rotational force into the axial direct power by the action of the shaft side screw groove 7a. That is, the screw shaft 7 is moved in a direction extending from the communication hole 3d of the extending side housing 3 (see black arrow). As a result, when the pin 7c is pressed against the left side surface 5b of the one-side detent groove 5a (see the solid line arrow), the pin 7c moves from the start end (the last retracted position of the screw shaft 7) of the one-side detent groove 5a toward the end. (See dashed arrows).

  As shown in FIG. 4B, when the pin 7c of the screw shaft 7 reaches the first left step 5c on the left side surface 5b of the one-side detent groove 5a of the sleeve 5, the pin 7c is separated from the left side surface 5b. The screw shaft 7 is rotated counterclockwise until the pin 7c is engaged with the left side surface 5b of the range enlarged by the first left step 5c of the one-side detent groove 5a by the counterclockwise rotational force (B arrow). (See the white arrow in the cross-sectional view). In the ball screw 6, the rotation of the screw shaft 7 is restricted by the pin 7c engaging with the left side surface 5b of the range enlarged by the first left step 5c in the one-side detent groove 5a. The screw shaft 7 is further moved in the direction of the other side end by converting the counterclockwise rotational force into axial direct power by the action of the shaft side thread groove 7a (see the black arrow). Similarly, when the pin 7c reaches the second left step 5d of the left side surface 5b of the one-side detent groove 5a, the pin 7c is separated from the portion of the left side surface 5b enlarged by the first left step 5c. The screw shaft 7 is rotated counterclockwise until the pin 7c is engaged with a portion of the left side surface 5b of the one-side detent groove 5a enlarged by the second left step 5d by the counterclockwise rotational force. In the ball screw 6, the rotation of the screw shaft 7 is restricted by engaging a portion of the left side surface 5 b of the one-side detent groove 5 a enlarged by the second left step 5 d with the pin 7 c. In this manner, the pin 7c is pressed against the left side surface 5b of the one-side detent groove 5a (see the solid line arrow) while descending the first left step 5c and / or the second left step 5d. The side detent groove 5a is moved from the start end toward the end (see broken line arrow).

  When the rotational force from the electric motor 4 is interrupted, the ball screw 6 allows the nut 8 to freely rotate. For this reason, in the ball screw 6, when an axial external force is applied to the screw shaft 7, the nut 8 is rotated and the screw shaft 7 is moved in the axial direction.

  As shown in FIG. 5A, when an external force in the axial direction is applied to the screw shaft 7 from the other side end to the one side end in a state where the rotational force from the electric motor 4 is interrupted. (Refer to the shaded arrow), a counterclockwise rotational force (see the shaded arrow in the cross-sectional view of the arrow C) is generated in the screw shaft 7 by the action of the shaft-side screw groove 7a. When the pin 7c of the screw shaft 7 is engaged with the left side surface 5b of the range enlarged by the first left step 5c which is a predetermined position in the one-side detent groove 5a, the pin 7c It is pressed against the left side surface 5b by the rotational force (see solid line arrow). At the same time, the pin 7c moves toward the first left step 5c while being pressed against the left side surface 5b by an external force applied from the other side end to the one side end applied to the screw shaft 7 (see broken line arrow). When the pin 7c is engaged with the first left step 5c, the screw shaft 7 stops against an external force applied from the other end of the screw shaft 7 toward the one end. Thereby, the ball screw 6 is switched to a state in which the movement in the axial direction from the other side end of the screw shaft 7 toward the one side end is restricted by the first left step 5c which is a position holding structure. The ball screw 6 maintains its position against an external force in the axial direction in which the screw shaft 7 moves from the other side end to the one side end.

  Similarly, when the pin 7c of the screw shaft 7 is engaged with the left side surface 5b of the range enlarged by the second left step 5d which is a predetermined position in the one-side detent groove 5a, the pin 7c is The screw shaft 7 moves toward the second left step 5d while being pressed against the left side surface 5b by the force of moving from the other side end to the one side end. When the pin 7c engages with the second left step 5d, the screw shaft 7 stops against an external force applied from the other end of the screw shaft 7 toward the one end. Thereby, the ball screw 6 is switched to a state in which the movement in the axial direction from the other side end of the screw shaft 7 toward the one side end is restricted by the second left step 5d which is a position holding structure. The ball screw 6 maintains its position against an external force in the axial direction in which the screw shaft 7 moves from the other side end to the one side end.

  Further, when the external force applied to the screw shaft 7 disappears while the rotational force from the electric motor 4 is cut off, the ball screw 6 moves the screw shaft 7 generated on the screw shaft 7 from one end to the other side. The force to move to the end and the counterclockwise rotational force due to external force disappear. However, in the ball screw 6, the pin 7c of the screw shaft 7 is engaged with the first left step 5c or the second left step 5d. That is, the movement of the pin 7c of the screw shaft 7 to one side of the ball screw 6 is restricted by the first left step 5c or the second left step 5d. Thereby, the state in which the ball screw 6 restricts the movement of the screw shaft 7 to one side of the ball screw 6 regardless of the presence or absence of the electric motor 4 or external force is maintained.

  As shown in FIG. 5B, when the nut 8 is rotated counterclockwise by the rotational force from the electric motor 4, the counterclockwise rotational force generated by the electric motor 4 is generated on the screw shaft 7. (See the white arrow in the cross-sectional view of arrow D). The screw shaft 7 is moved in a direction extending from the communication hole 3d of the extension side housing 3 by converting the counterclockwise rotational force into an axial direct power by the action of the shaft side screw groove 7a (see the black arrow). ). As a result, the pin 7c moves to the end of the one-side detent groove 5a (the maximum extension position of the screw shaft 7) while being pressed against the left side surface 5b of the one-side detent groove 5a (see the solid line arrow). The pin 7c enters the other-side moving groove 5f connected to the terminal end of the one-side detent groove 5a by the counterclockwise rotational force generated in the screw shaft 7. The screw shaft 7 has a left side surface 5h of the other-side detent groove 5g (one other-side detent groove 5g) in which the pin 7c is connected to the one-side detent groove 5a via the other-side movement groove 5f. It rotates counterclockwise until it engages with (see the white arrow in the cross-sectional view of arrow E). Thereby, the ball screw 6 is switched to a state in which the screw shaft 7 is movable in one direction.

  As shown in FIG. 6A, when the nut 8 is rotated clockwise by the rotational force from the electric motor 4 to retract the screw shaft 7, the ball screw 6 is screwed by the inclination of the shaft-side screw groove 7a. A clockwise rotational force is generated on the shaft 7 (see the white arrow in the cross-sectional view of the arrow E). The screw shaft 7 is restricted from rotating counterclockwise by the engagement of the left side surface 5h of the other-side detent groove 5g and the pin 7c, but is not restricted from rotating clockwise by the other-side moving groove 5f. . On the other hand, a counterclockwise rotational force is applied to the screw shaft 7 by an external force in the axial direction from the other side end to the one side end (see the shaded arrow in the cross-sectional view of the arrow E). Therefore, in the screw shaft 7, the pin 7c is engaged with the left side surface 5h of the other-side detent groove 5g by the counterclockwise rotational force obtained by subtracting the clockwise rotational force by the nut 8 from the counterclockwise rotational force by the external force. Thus, the rotation of the screw shaft 7 is restricted.

  As the ball screw 6 rotates in the clockwise direction of the nut 8, the screw shaft 7 moves in one direction. That is, the screw shaft 7 moves in the direction of retreating toward the communication hole 3d of the extending side housing 3 (see the black arrow). At this time, when the counterclockwise rotational force obtained by subtracting the clockwise rotational force of the nut 8 from the counterclockwise rotational force generated by the external force is generated, the screw shaft 7 is formed on the left side surface 5e of the other-side detent groove 5g. The rotation of the screw shaft 7 is prevented by the engagement of the pin 7c. Further, when only the clockwise rotational force is generated by the nut 8, the screw shaft 7 restricts the rotation around the shaft by engaging the pin 7c with the right side surface 5i of the other-side detent groove 5g. Yes. As a result, the pin 7c is pressed against the left side surface 5h or the right side surface 5i of the other side detent groove 5g (see solid arrow), and the end of the other side detent groove 5g (the last retracted position of the screw shaft 7). Move up. (See dashed arrow).

  As shown in FIG. 6B, when the nut 8 is rotated counterclockwise by the rotational force from the electric motor 4 in order to extend the screw shaft 7, the ball screw 6 rotates counterclockwise on the screw shaft 7. (See the white arrow in the F arrow cross-sectional view). The pin 7c enters the one-side moving groove 5j connected to the terminal end of the other-side detent groove 5g by the counterclockwise rotational force generated in the screw shaft 7. The screw shaft 7 has a left side surface 5b of the one-side detent groove 5a (the other one-side detent groove 5a) in which the pin 7c is connected to the other-side detent groove 5g via the one-side movement groove 5j. Rotate counterclockwise until it engages (see dashed arrow). Thereby, the ball screw 6 is switched to a state in which the screw shaft 7 is movable in the other direction. Further, in the ball screw 6, the rotation of the screw shaft 7 is restricted by the engagement between the left side surface 5b of the one-side detent groove 5a and the pin 7c.

  Thereafter, as shown in FIGS. 4 to 6, the pin 7c is moved from the start end to the end of the one-side detent groove 5a. When the pin 7c reaches the end of the one-side detent groove 5a, the screw shaft 7 is engaged with the left side surface of the other-side detent groove 5g (the other other-side detent groove 5g) through the other-side movement groove 5f. It is rotated counterclockwise. Thereby, the ball screw 6 is switched to a state in which the screw shaft 7 is movable in one direction. The pin 7c is moved from the start end to the end (the last retracted position of the screw shaft 7) of the other-side detent groove 5g. When the pin 7c reaches the end of the other-side detent groove 5g, the screw shaft 7 is engaged with the left side surface of the one-side detent groove 5a (one one-side detent groove 5a) through the one-side movement groove 5j. It is rotated counterclockwise.

  By configuring as described above, the electric actuator 1 with a position holding function is a position holding structure formed in the two one-side detent grooves 5 a when an axial external force is applied to the screw shaft 7 of the ball screw 6. The pin 7c is engaged with the first left step 5c or the second left step 5d. In addition, the electric actuator 1 with a position holding function includes the one-side detent groove 5a provided with a step by the axial movement of the screw shaft 7 and the rotation around the axis, and the other-side detent groove 5g provided with no step. The pin 7c is continuously moved between. Thereby, position holding | maintenance can be cancelled | released easily, hold | maintaining the position of the screw shaft 7 which is a linear motion member stably. Further, the electric actuator 1 with a position holding function is configured such that the screw shaft 7 has a position depending on the positions of the first left step 5c and the second left step 5d formed in the one-side detent groove 5a that constitutes the detent portion of the ball screw 6. The holding position is determined. That is, the electric actuator 1 with a position holding function can hold the screw shaft 7 at an arbitrary position during one stroke of the screw shaft 7 of the ball screw 6.

  Next, the electric actuator 12 with a position holding function which is a second embodiment of the electric actuator with a position holding function according to the present invention will be described with reference to FIG. The electric actuator with position holding function according to all of the following embodiments is applied in place of the electric actuator 1 with position holding function in the electric actuator 1 with position holding function shown in FIGS. By using the names, figure numbers, and symbols used in the description, the same thing is pointed out, and in the following embodiments, the specific description is omitted with respect to the same points as the already described embodiments, and is different. The explanation will focus on the part.

  As shown in FIG. 7 (a), the electric actuator 12 with a position holding function converts a rotary motion from an electric power source into a linear motion and outputs the linear motion. The electric actuator 12 with a position holding function includes a sleeve 13 and a ball screw 6.

  The sleeve 13 regulates the rotation of the screw shaft 7. On the inner peripheral surface of the sleeve 13, four one-side anti-rotation grooves 13 a and four other-side anti-rotation grooves 13 e that are concave grooves with a predetermined depth extending along the axial direction are formed. The four one-side detent grooves 13a and the four other-side detent grooves 13e are alternately arranged in the counterclockwise direction along the circumferential direction on the inner peripheral surface of the sleeve 13. At this time, the four one-side anti-rotation grooves 13a and the four other-side anti-rotation grooves 13e are arranged so that two grooves of the same type are opposed to each other as one set.

  In the four one-side detent grooves 13a, a step 13c as a position holding structure is formed at an arbitrary position on the left side surface 13b. The end of the first one-side detent groove 13a (the extending side of the screw shaft 7) is the other end of the first other-side detent groove 13e provided on the left side thereof (the extending side of the screw shaft 7). It is connected via a side movement groove 13d. The end of the first other-side detent groove 13e (retreat side of the screw shaft 7) is connected to the start end of the second one-side detent groove 13a provided on the left side of the first other-side detent groove 13e via the one-side movement groove 13f. It is connected. Similarly, the second one-side anti-rotation groove 13a, the second other-side anti-rotation groove 13e, the third one-side anti-rotation groove 13a, the third other-side anti-rotation groove 13e, and the fourth one-side rotation The stop groove 13 a and the fourth other-side detent groove 13 e are arranged along the circumferential direction on the inner peripheral surface of the sleeve 13, and are configured as a single groove that goes around the inner peripheral surface of the sleeve 13.

  As shown in FIG. 7 (b), a substantially cylindrical sliding portion (without sliding) is provided at one end of the screw shaft 7, which is one side of the ball screw 6 (retreat side of the screw shaft 7). 7b is also formed. The sliding portion 7b is provided with four pins 7c projecting in the radial direction at positions facing the four one-side detent grooves 13a or the four other-side detent grooves 13e of the sleeve 13, respectively. The four pins 7c are formed to have a diameter that allows the four one-side detent grooves 13a, the four other-side detent grooves 13e, the one-side movement groove 13f, and the other-side movement groove 13d of the sleeve 13 to slide. Yes. The four pins 7c are simultaneously engaged with the four one-side detent grooves 13a or the four other-side detent grooves 13e. As a result, the play is canceled out by the combination of the four one-side detent grooves 13a or the four other-side detent grooves 13e and the four pins 7c.

  With the configuration as described above, the electric actuator 12 with a position maintaining function suppresses backlash between the one-side detent groove 13a or the other-side detent groove 13e and the pin 7c by providing a plurality of pins 7c on the screw shaft 7. Is done. Thereby, the electric actuator 12 with a position holding function can easily release the position holding while stably holding the position of the linear motion member.

  Next, the electric actuator 14 with a position holding function which is a third embodiment of the electric actuator with a position holding function according to the present invention will be described with reference to FIG.

  As shown in FIG. 8, the electric actuator 14 with a position holding function converts a rotary motion from an electric power source into a linear motion and outputs the linear motion. The electric actuator 14 with a position holding function includes a sleeve 15 and a ball screw 6.

  The sleeve 15 regulates the rotation of the screw shaft 7. On the inner peripheral surface of the sleeve 15, there are two A-type one-side detent grooves 15a, two B-type one-side detent grooves 15f and four other sides, which are concave grooves of a predetermined depth extending along the axial direction. An anti-rotation groove 15d is formed. An A step 15b, which is a position holding structure, is formed in the A-type one-side detent groove 15a. A B step 15g, which is a position holding structure, is formed in the B-type one-side detent groove 15f. The A step 15b and the B step 15g are the length La from the start end (retreat side end of the screw shaft 7) to the A step 15b in the A-type one-side detent groove 15a and the start end in the B-type one-side detent groove 15f. The length Lb from the (rear side end portion of the screw shaft 7) to the B step 15g is provided to be different. The two A-type one-side detent grooves 15a, the two B-type one-side detent grooves 15f, and the four other-side detent grooves 15d are counterclockwise along the circumferential direction, and one A-type one-side detent groove 15a, the other-side detent groove 15d, one B-type one-side detent groove 15f, the other-side detent groove 15d, the other A-type one-side detent groove 15a, the other-side detent groove 15d, the other B-type one The side detent grooves 15f and the other side detent grooves 15d are alternately arranged in this order. At this time, the two A-type one-side detent grooves 15a, the two B-type one-side detent grooves 15f, and the four other-side detent grooves 15d are configured so that two grooves of the same type are opposed to each other as one set. Is arranged.

  The end of one A-type one-side detent groove 15a (the extension side of the screw shaft 7) moves to the other side to the start end (the extension side of the screw shaft 7) of the other-side detent groove 15d provided on the left side thereof. It is connected via the groove 15c. The terminal end of the other-side detent groove 15d (retracted side of the screw shaft 7) is connected to the start end of one B-type one-side detent groove 15f provided on the left side via a one-side movement groove 15e. ing. Further, the terminal end of one B-type one-side detent groove 15f is connected to the start end of the other-side detent groove 15d provided on the left side via the other-side moving groove 15c. The terminal end of the other-side detent groove 15d is connected to the starting end of the other A-type one-side detent groove 15a provided on the left side via a one-side movement groove 15e. Similarly, the other A-type one-side detent groove 15a and the other-side detent groove 15d and the other B-type one-side detent groove 15f and the other-side detent groove 15d are alternately connected.

  With the configuration as described above, the electric actuator 14 with a position maintaining function is positioned by the A-type one-side detent groove 15a and the B-type one-side detent groove 15f having different step positions between the A step 15b and the B step 15g. It is held. Thereby, the electric actuator 14 with a position holding function can hold the screw shaft 7 at a different position for each stroke of the screw shaft 7 of the ball screw 6 only by changing the shape of the detent groove.

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

  As shown to Fig.9 (a), the electric actuator 16 with a position holding function converts the rotational motion from an electric power source into a linear motion, and outputs it. The electric actuator 16 with a position holding function includes a sleeve 17 and a ball screw 6 that is a linear motion mechanism.

  The sleeve 17 regulates the rotation of the screw shaft 18. Two pins 17 a are provided on the inner peripheral surface of the sleeve 17 so as to protrude radially inward. The two pins 17a are arranged so as to face each other. The pin 17a is formed to have a diameter capable of sliding in two one-side detent grooves 18b and two other detent grooves 18d of the screw shaft 18 described later. The pin 17a forms a detent portion.

  The ball screw 6 converts rotational motion into linear motion. The ball screw 6 includes a screw shaft 18, a nut 8, a plurality of balls 9, and the like.

  A substantially cylindrical sliding portion (not required to slide) 18 a is formed at one end of the screw shaft 18. The sliding portion 18 a is formed to have a diameter that can be slidably inserted into the sleeve 17. On the outer peripheral surface of the sliding portion 18a, two one-side anti-rotation grooves 18b and two other anti-rotation grooves 18d that are concave grooves of a predetermined depth extending along the axial direction are alternately turned clockwise in the circumferential direction. It is provided side by side. The one-side detent groove 18b and the other-side detent groove 18d constitute a detent portion.

  In the ball screw 6 configured in this way, a sliding portion 18 a at one end of the screw shaft 18 is slidably inserted into the sleeve 17. At this time, in the screw shaft 18, the two pins 17a of the sleeve 17 are slidably engaged with the two one-side detent grooves 18b or the two other detent grooves 18d of the sliding portion 18a. As described above, the ball screw 6 includes a rotation preventing portion including the one-side rotation prevention groove 18 b or the other-side rotation prevention groove 18 d of the sliding portion 18 a of the screw shaft 18 and the pin 17 a of the sleeve 17.

  As shown in FIG. 9B, the two one-side detent grooves 18b and the two other-side detent grooves 18d of the screw shaft 18 engage the two pins 17a of the screw shaft 18 that is a linear motion member. Is. The two one-side anti-rotation grooves 18b and the two other-side anti-rotation grooves 18d are clockwise along the circumferential direction of the sleeve 17, one other-side anti-rotation groove 18d, one one-side anti-rotation groove 18b, and the other The other-side detent groove 18d and the other one-side detent groove 18b are alternately arranged in this order. At this time, the two one-side anti-rotation grooves 18b and the two other-side anti-rotation grooves 18d are arranged so that the one-side anti-rotation grooves 18b face each other, and the other-side anti-rotation grooves 18d face each other. Has been. A first right step 18f and a second right step 18g, which are position holding structures, are formed in the two other-side detent grooves 18d at arbitrary positions on the right side surface 18e. The two one-side detent grooves 18b are formed on the side surface having no step.

  The terminal end of one other-side detent groove 18d (retreat side of the screw shaft 18) is the start end (retreat of the screw shaft 18) of one one-side detent groove 18b provided adjacent to the right side surface 18e. Side) through one side moving groove 18h. The one-side moving groove 18h is formed at one end of the sliding portion 18a so as to extend clockwise. That is, the terminal end of one other-side detent groove 18d is connected to the starting end of one one-side detent groove 18b provided on the right side via the one-side movement groove 18h. Further, the other end of the one-side detent groove 18b (the extending side of the screw shaft 18) is provided adjacent to the right side surface 18e of the one-side detent groove 18b. The other end moving groove 18c is connected to the starting end of 18d (the extending side of the screw shaft 18). The other-side moving groove 18c is formed at the other end of the sliding portion 18a so as to extend clockwise. That is, the terminal end of one one-side detent groove 18b is connected to the start end of the other other-side detent groove 18d provided on the right side.

  Similarly, the terminal end of the other one-side detent groove 18d is connected to the start end of the other one-side detent groove 18b provided on the right side via a one-side movement groove 18h. The end of the other one-side detent groove 18b is connected to the start end of one other-side detent groove 18d provided on the right side via the other-side moving groove 18c. As described above, the two one-side anti-rotation grooves 18b and the two other-side anti-rotation grooves 18d that are alternately arranged along the circumferential direction of the outer peripheral surface of the sliding portion 18a include the one-side movement groove 18h. The other side moving grooves 18c are alternately connected to each other, and are configured as one groove that goes around the outer peripheral surface of the sliding portion 18a. Two pins 17a provided on the sleeve 17 are inserted into the two one-side detent grooves 18b or the two other-side detent grooves 18d, respectively.

  By configuring as described above, the electric actuator 16 with a position holding function is a first right holding structure that is formed in the other-side detent groove 18d when an axial external force is applied to the screw shaft 18 of the ball screw 6. The pin 17a is engaged with the step 18f or the second right step 18g. Thereby, the electric actuator 16 with a position holding function can easily release the position holding while stably holding the position of the screw shaft 18 that is the linear motion member.

  Next, the electric actuator 19 with a position holding function which is a fifth embodiment of the electric actuator with a position holding function according to the present invention will be described with reference to FIGS. 10 and 11.

  As shown in FIG. 10, the electric actuator 19 with a position holding function converts a rotary motion from an electric power source into a linear motion and outputs it. The electric actuator 19 with a position holding function includes a storage side housing 20, an extension side housing 3, a shaft end housing 21, an electric motor 4, a ball screw 22 that is a linear motion mechanism, a sleeve 25, and a gear reduction mechanism 11. The electric actuator 19 with a position holding function is configured to be able to move a nut 24 described later to an arbitrary position by controlling the movement of the electric motor 4.

  The storage housing 20 is formed with a ball bearing holding portion 20a. The ball bearing holding portion 20 a is formed on one side surface of the storage side housing 20. Further, the ball bearing holding portion 20a is formed so as to hold a ball bearing 10 that rotatably supports a screw shaft 23 of a ball screw 22 described later.

  The shaft end housing 21 supports the screw shaft 23 of the ball screw 22. The shaft end housing 21 is fixed to a base (not shown) to which the extension side housing 3 and the storage side housing 20 are fixed. The shaft end housing 21 is formed so as to hold the ball bearing 10 that rotatably supports the screw shaft 23.

  The ball screw 22 converts rotational motion into linear motion. The ball screw 22 includes a screw shaft 23, a nut 24, a plurality of balls 9, a ball bearing 10, and the like.

  A cylindrical one-side support portion 23 a and another-side support portion 24 b are formed at one end and the other end of the screw shaft 23. Ball bearings 10 are provided at both end portions of the one side support portion 23a. The ball bearings 10 are respectively held by the ball bearing holding part 3 c of the extension side housing 3 and the ball bearing holding part 20 a of the storage side housing 20. Similarly, the ball bearing 10 is provided in the other side support part 24b. The ball bearing 10 is held by the shaft end housing 21. That is, the screw shaft 23 is rotatably supported by the extension side housing 3, the storage side housing 20, and the shaft end housing 21 via the ball bearing 10.

  The outer peripheral surface of the nut 24 is formed in a diameter that can be slidably inserted into the sleeve 25 without a gap. The nut 24 is supported via a plurality of balls 9 so as to be rotatable about the axis of the screw shaft 23. The nut 24 is formed with two pins 24a projecting in the radial direction at positions facing the two one-side detent grooves 25a of the sleeve 25 or the two other-side detent grooves 25d. The pin 24a forms a detent portion.

  As shown in FIG. 11, the sleeve 25 regulates the rotation of the nut 24. The sleeve 25 is fixed to a base (not shown) to which the extension side housing 3 and the storage side housing 20 are fixed. That is, the sleeve 25 is configured so as not to rotate relative to the nut 24. The inner peripheral surface of the sleeve 25 has a diameter that allows the nut 24 to be slidably inserted without a gap. On the inner peripheral surface of the sleeve 25, two one-side detent grooves 25a and two other-side detent grooves 25d extending in the axial direction are formed at positions facing the pins 24a of the nut 24. The two one-side anti-rotation grooves 25a and the two other anti-rotation grooves 25d are formed to have a width that allows the pin 24a to slide. The two one-side detent grooves 25a and the two other-side detent grooves 25d constitute a detent portion. A first left step 25b and a second left step 25c, which are position holding structures, are formed in the two one-side detent grooves 25a.

  In the ball screw 22 configured in this manner, the ball bearing 10 provided on the one side support portion 23a of the screw shaft 23 is held by the extension side housing 3 and the storage side housing 20, and the other side support portion 24b The provided ball bearing 10 is held by the shaft end housing 21. That is, the screw shaft 23 is rotatably supported by the storage side housing 20, the extension side housing 3 and the shaft end housing 21 via the ball bearing 10. The ball screw 22 is slidably inserted into a sleeve 25 in which a nut 24 is integrally fixed to a base (not shown). At this time, the two pins 24a of the nut 24 are slidably engaged with the two one-side detent grooves 25a or the two other detent grooves 25d of the sleeve 25. As described above, the ball screw 22 includes a non-rotating portion including the two pins 24a of the nut 24, the two one-side detent grooves 25a and the two other detent grooves 25d of the sleeve 25. That is, the nut 24 is inserted into the sleeve 25 so as not to rotate relative to the screw shaft 23 while being rotatably supported around the screw shaft 23. In the ball screw 22, the rotational force is transmitted to the nut 24 when the screw shaft 23 is rotated. Since the nut 24 is inserted into the sleeve 25 so as not to rotate relative to the sleeve 25, the rotational movement of the nut 24 is converted into a linear movement in the axial direction of the screw shaft 23. In this way, the nut 24 of the ball screw 22 reciprocates in the axial direction on the screw shaft 23 while being inserted into the sleeve 25.

  The drive side gear 11a, the driven side gear 11b, and the idle gear 11c are arranged in the gear reduction mechanism arrangement portion 3b of the extension side housing 3 in an engaged state. The driven gear 11b is provided so that the one-side support portion 23a of the screw shaft 23 is inserted into a support shaft insertion hole formed at the center thereof so as to be integrally rotatable.

  The electric actuator 19 with the position holding function configured as described above has a speed and axial thrust according to the lead of the screw shaft 23 by rotating the screw shaft 23 of the ball screw 22 provided with the driven gear 11b. Thus, the nut 24 linearly moves in the axial direction (see the black arrow in FIG. 10).

  With the configuration as described above, the electric actuator 19 with a position holding function is a first left holding structure that is formed in the one-side detent groove 25a when an axial external force is applied to the nut 24 of the ball screw 22. The pin 24a is engaged with the step 25b and the second left step 25c. Thereby, position holding | maintenance can be cancelled | released easily, hold | maintaining the position of the screw shaft 23 which is a linear motion member stably.

  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 with position holding function 4 Electric motor 5 Sleeve 5a One side detent groove 5c First left step 5d Second left step 5g Other side detent groove 6 Ball screw 7 Screw shaft 7c Pin 8 Nut

Claims (5)

In the electric actuator with position holding function that transmits the rotational force from the electric motor to the ball screw,
One-side detent for restricting rotation around the axis of the linear member that is moved from one side of the ball screw toward the other side by the rotational force from the electric motor of the screw shaft and nut constituting the ball screw Groove,
The other-side detent groove for restricting the rotation of the linear motion member that is moved from the other side of the ball screw toward the one side by the rotational force from the electric motor;
A pin engageable with the one-side detent groove and the other-side detent groove;
With
A step is formed in the plurality of one-side anti-rotation grooves or the plurality of other-side anti-rotation grooves to restrict axial movement of the linear motion member by an external force, and the pin is connected to the one-side anti-rotation groove and the other side. An electric actuator with a position holding function configured to be movable between the rotation preventing groove. A sleeve into which the linear motion member is slidably inserted;
A plurality of the one-side detent grooves and a plurality of the other-side detent grooves formed along the axial direction of the linear motion member are provided alternately in the circumferential direction of the sliding surface of the sleeve,
The pin is provided on the sliding surface of the linear motion member;
The step is a side surface of the plurality of one-side detent grooves or a side surface of the plurality of the other-side detent grooves, and the pin is pressed by a rotational force generated when an axial external force is applied to the linear motion member. Is provided to dent the side
Of the plurality of one-side anti-rotation grooves or the plurality of other-side anti-rotation grooves, the terminal is provided adjacent to the end side of the groove provided with the step and the side surface provided with the step. The groove is connected to a start end side of the groove, and a start end side of the groove provided with the step is connected to a terminal end side of the groove provided on the side surface opposite to the side surface provided with the step. The electric actuator with a position holding function described in 1. A sleeve into which the linear motion member is slidably inserted;
A plurality of the one-side detent grooves and a plurality of the other-side detent grooves formed along the axial direction of the linear motion member are alternately provided along the axial direction on the sliding surface of the linear motion member. And
The pin is provided on the sliding surface of the sleeve;
The step is a side surface of the plurality of one-side detent grooves or a side surface of the plurality of the other-side detent grooves, and the pin is pressed by a rotational force generated when an axial external force is applied to the linear motion member. Is provided to dent the side
Of the plurality of one-side anti-rotation grooves or the plurality of other-side anti-rotation grooves, the terminal is provided adjacent to the end side of the groove provided with the step and the side surface provided with the step. The groove is connected to a start end side of the groove, and a start end side of the groove provided with the step is connected to a terminal end side of the groove provided on the side surface opposite to the side surface provided with the step. The electric actuator with a position holding function described in 1.   The step is a side surface of the plurality of one-side detent grooves or a side surface of the plurality of the other-side detent grooves, and the side surface on which the pin is pressed by a rotational force generated by an external force applied to the linear motion member. The electric actuator with a position holding function according to any one of claims 1 to 3, wherein a plurality of the actuators are provided at an arbitrary position.   The electric actuator with a position holding function according to any one of claims 1 to 4, wherein a plurality of the pins are arranged along a circumferential direction of the linear motion member or the sleeve.

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