JP2016056919A - Linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear actuator which moves a cylinder body by converting the rotational motion of a screw shaft to the linear motion of a nut, and in which slide resistance to the cylinder body is small, and the shaft vibration of the screw shaft is prevented by a vibration prevention member which is excellent in productivity and durability.SOLUTION: A vibration prevention member comprises a support body part which is supported to an end part of a screw shaft, and has a clearance toward a radial direction of a cylinder body between an internal peripheral face of the cylinder body and itself. A plurality of recesses which oppose the internal peripheral face of the cylinder body, and have shapes progressing toward an internal diameter direction from a peripheral edge are formed at the support body part at different positions in a circumferential direction. The vibration prevention member further comprises an elastic abutment part which is extended from a base end part located in a position between a plurality of the recesses at a peripheral edge of the support body part up to a free end located in a position different from that of the base end part in an axial line direction of the screw shaft, and located in an outside diameter direction rather than the base end part, slidably abuts on the internal peripheral face of the cylinder body, and is elastically deformable to the radial direction of the cylinder body.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a linear actuator that converts a rotational movement of a screw shaft into a linear movement of a nut to move a cylinder forward and backward.

  A screw shaft is disposed inside the cylindrical tube, and includes a nut that is screwed onto the screw shaft and is restricted in rotation and coupled to the tube. When the screw shaft rotates, the nut and the tube are connected to the screw shaft. A linear actuator that linearly moves in the axial direction is known (for example, Patent Document 1).

  In this type of linear actuator, the base end side of the screw shaft, which is a long member, is connected to the rotation drive mechanism, while the tip end of the screw shaft is a free end inserted into the cylinder. This is a structure in which shaft runout is likely to occur. In particular, in order to increase the amount of movement of the cylinder, the nut is often fixed to the base end side of the cylinder, and when the screw shaft is housed in the cylinder, the runout width of the distal end portion of the screw shaft is small. Easy to grow. Since the shaft runout of the screw shaft causes abnormal noise and vibration, suppression is required. As a countermeasure, a configuration is known in which a vibration preventing member capable of sliding contact with the inner peripheral surface of the cylinder is provided at the tip of the screw shaft. As the vibration preventing member, an annular resin bearing made of synthetic resin is used. However, if the degree of close contact (contact pressure) of the anti-vibration member with the inner peripheral surface of the cylinder is too high, the sliding resistance increases, the load on the drive source of the linear actuator increases, and the cylinder operates smoothly. Therefore, it was necessary to strictly manage the relationship between the outer diameter size of the shake preventing member and the inner diameter size of the cylindrical body.

  In Patent Document 2, by setting the shape of a vibration preventing member (referred to as a piston ring), smooth sliding with respect to the cylindrical body is achieved while suppressing the shaft vibration of the screw shaft. Specifically, a thin-walled contact portion that opens a hole (a long hole in the circumferential direction) in the vicinity of the periphery of the vibration preventing member and contacts the outer diameter side region of the hole with the inner peripheral surface of the cylindrical body It is said. Flexibility is given to the contact portion by the hole, and the contact portion comes into contact with the inner peripheral surface of the cylindrical body while being bent.

JP 2004-308741 A US Pat. No. 5,964,454

  When the vibration preventing member is small, high molding accuracy is required to form a thin contact portion by penetrating a hole in the vicinity of the periphery as in Patent Document 2, and the manufacturing effort and cost are reduced. There is a problem that it takes. In addition, since the load received by the contact portion is concentrated in a narrow region (base end portion supporting the contact portion) on both sides of the hole, a problem is likely to occur in terms of durability of the shake preventing member.

  The present invention has been made in view of the above problems, and is a linear actuator that moves the cylinder by converting the rotational movement of the screw shaft into the linear movement of the nut. It aims at preventing the axial run-out of the screw shaft by the anti-vibration member excellent in property and durability.

  The present invention relates to a cylindrical tube whose rotation is restricted, a screw shaft that can be driven to rotate, and a screw shaft that is supported in the tube and screwed into the screw shaft. In a linear actuator having a nut that moves linearly in the axial direction of a screw shaft, attention is paid to a vibration preventing member attached to an end portion of the screw shaft. The anti-vibration member includes a support body portion that is supported by an end portion of the screw shaft and has a radial clearance between the cylindrical body and the inner peripheral surface of the cylinder body. A plurality of recesses shaped in the inner diameter direction from the peripheral edge facing the surface are formed at different positions in the circumferential direction. The vibration preventing member further has a position in the axial direction of the screw shaft that is different from the base end portion located between the plurality of recesses at the periphery of the support body portion, and is outside the base end portion. An elastic contact portion is provided that extends to a free end located in the radial direction, slidably contacts the inner peripheral surface of the cylindrical body, and is elastically deformable in the radial direction of the cylindrical body.

  The vibration preventing member can move in the radial direction in the cylinder while bending the elastic contact portion, and the deflection amount of the elastic contact portion can be reduced by bringing the base end portion into contact with the inner peripheral surface of the cylinder. It is preferable to limit.

  It is preferable to provide a protruding portion protruding in the outer diameter direction at the free end of the elastic contact portion, and to contact the protruding portion with the inner peripheral surface of the cylindrical body. Thereby, it becomes easy to bend an elastic contact part.

  The shake preventing member may be rotatable relative to the screw shaft, or may be rotated integrally with the screw shaft. As an example, by adopting a configuration that allows relative rotation with respect to the screw shaft, it becomes easy to reduce friction between the vibration preventing member and the inner peripheral surface of the cylindrical body.

  According to the linear actuator of the present invention described above, the shaft runout when the screw shaft rotates can be prevented by the shake preventing member that has a small sliding resistance with respect to the cylindrical body, is easy to manufacture, and has excellent durability.

It is the figure which showed the linear actuator to which this invention was applied partially in cross section. It is a perspective view of the bearing top of 1st Embodiment attached to the front-end | tip of the screw shaft of a linear actuator. It is a front view of the bearing top of 1st Embodiment. It is a side view of the bearing top of 1st Embodiment. It is a sectional side view of the bearing top of 1st Embodiment when an elastic contact part exists in a free state. It is a sectional side view which shows the state which inserted the bearing top of 1st Embodiment in the inner tube. It is a sectional side view which shows the state which the bearing top of 1st Embodiment changed the position to radial direction with respect to the center of an inner tube. It is a perspective view which shows the bearing top of 2nd Embodiment. It is a side view of the bearing top of 2nd Embodiment. It is a figure which shows the example which used the linear actuator to which this invention is applied as a drive means of the power trunk lid of a motor vehicle.

  A linear actuator 10 shown in FIG. 1 includes a cylindrical outer tube 11, a cylindrical inner tube 12 (inner surface is denoted by reference numeral 12 a) inserted inside the outer tube 11, and an inner tube 12. The screw shaft 13 is positioned, and the drive block 14 is connected to one end of the outer tube 11. The outer tube 11, the inner tube 12, and the screw shaft 13 are disposed concentrically with the axis line directed in the left-right direction in FIG. In the following description, the side where the drive block 14 is provided (the right side in FIG. 1) is the base end side of the linear actuator 10, and the opposite side (the left side in FIG. 1) is the front end side of the linear actuator 10.

  The base end of the outer tube 11 is fixed to the drive block 14. The drive block 14 is provided with a motor 15, and when the motor 15 is driven, the driven gear 16 in the drive block 14 similarly rotates via a speed reduction mechanism (not shown) in the drive block 14. The driven gear 16 is connected to the base end of the screw shaft 13, and the screw shaft 13 and the driven gear 16 rotate integrally. A feed screw (male screw) is formed on the outer peripheral surface of the screw shaft 13, and an inner tube 12 and a nut in which a nut 17 having a female screw to be engaged with the feed screw is fixed near the proximal end of the inner tube 12. 17 is supported so that the rotation is restricted with respect to the outer tube 11 and can move linearly in the axial direction. When the screw shaft 13 rotates, the inner tube 12 is axially moved by the screwed relationship between the screw shaft 13 and the nut 17. The amount of protrusion of the inner tube 12 in the distal direction relative to the outer tube 11 changes. That is, the linear actuator 10 expands and contracts. FIG. 1 shows a state where the protruding amount of the inner tube 12 is the smallest, and the position of the nut 17 at this time is shown by a solid line. The position of the nut 17 indicated by a two-dot chain line in FIG. 1 is that in which the protruding amount of the inner tube 12 with respect to the outer tube 11 is maximized. A socket 18 is fixed to the tip of the inner tube 12. Fastening holes 19 and 20 used for attaching the linear actuator 10 to the object are formed in the drive block 14 and the socket 18, respectively.

  Since the screw shaft 13 has a structure that is not supported by the outer tube 11 and the drive block 14 except for the base end portion connected to the driven gear 16, the shaft runout of the screw shaft 13 (the outer tube 11 and the It is necessary to consider the occurrence of the swinging motion of the screw shaft 13 relative to the axis of the inner tube 12. A bearing top 30 as an anti-vibration member is attached to the tip of the screw shaft 13 in order to reduce abnormal noise and vibration when the linear actuator 10 is expanded and contracted while preventing such axial oscillation. In the following description, the distal end side of the screw shaft 13 is the front side of the bearing top 30, and the proximal end side of the screw shaft 13 is the rear side of the bearing top 30.

  2 to 7 show the detailed structure of the bearing top 30 according to the first embodiment. The bearing top 30 is a molded product of a synthetic resin, and has a support body 32 having a substantially circular shaft insertion hole 31 formed in the center. A tip shaft portion 21 (FIG. 1) having a smaller diameter than the male screw forming portion is formed at the tip of the screw shaft 13, and the tip shaft portion 21 is inserted into the shaft insertion hole 31. The bearing top 30 is supported with respect to the distal end shaft portion 21 by restricting relative movement in the axial direction of the screw shaft 13 by a push nut or the like (not shown) so as not to drop off toward the distal end side of the screw shaft 13. On the other hand, in the rotational direction of the screw shaft 13, the bearing top 30 rotates together with the screw shaft 13 (the tip shaft portion 21), and the bearing top 30 can rotate relative to the screw shaft 13 (the tip shaft portion 21). It is possible to arbitrarily select the form to be performed.

  As can be seen from FIGS. 5 to 7, the support 32 has a thick central portion having a shaft insertion hole 31 through which the screw shaft 13 is inserted, and is away from the shaft insertion hole 31 in the outer diameter direction (peripheral side). Gradually reduce the wall thickness as you proceed. More specifically, the front surface of the support body 32 is formed in a flat shape, and the inclined shape (the portion having no top portion) is gradually approached as the rear surface of the support body 32 advances from the shaft insertion hole 31 in the outer diameter direction. A conical surface). Three recesses 33 that are recessed from the peripheral edge (outer peripheral surface) of the support 32 toward the inner diameter direction (direction approaching the shaft insertion hole 31) are formed. The three recesses 33 are formed at substantially equal intervals in the circumferential direction around the shaft insertion hole 31, and elastic contact portions 34 are formed at circumferential positions between the recesses 33. In other words, the bearing top 30 has three recesses 33 cut out from a rotating body having a center line C (FIGS. 4 to 7) passing through the center of the shaft insertion hole 31 and extending in the axial direction of the screw shaft 13. It has become a shape.

  Three base end portions 35 are provided on the periphery of the support body 32 between the three concave portions 33, and the elastic contact portions 34 protrude from the base end portions 35. The elastic contact portion 34 is a cantilever arm-like projecting portion extending rearward from the base end portion 35, and has a tip projection portion 36 at the rear end portion which is a free end. That is, the outer peripheral surface of the base end portion 35 (peripheral shape of the support 32 excluding the portion where the concave portion 33 is formed) is a cylindrical surface having a constant diameter centered on the center line C of the bearing top 30. On the other hand, the elastic contact portion 34 has a shape that gradually spreads in the outer diameter direction as it moves away from the base end portion 35 and moves backward. The tip protrusion 36 is formed thicker than the middle portion of the elastic contact portion 34, and protrudes larger in the outer diameter direction than the middle portion of the elastic contact portion 34.

  The elastic contact portion 34 can be elastically deformed in the radial direction of the inner tube 12 and the screw shaft 13 with a connection point with the base portion 35 as a fulcrum, and FIG. 5 shows the shape of the elastic contact portion 34 in a free state. . As can be seen from FIG. 5, the outer diameter size of the base end portion 35 (support 32) is smaller than the inner diameter size 12 b of the inner peripheral surface 12 a of the inner tube 12, and the outer peripheral surface of the base end portion 35 and the inner tube 12. There is a radial clearance between the inner peripheral surface 12a. On the other hand, the outer diameter size of the elastic contact portion 34 in the free state (the size obtained by adding the protruding amount in the outer diameter direction of the elastic contact portion 34 to the outer diameter size of the base end portion 35) is the inner diameter of the inner tube 12. It is set larger than the size 12b. Therefore, when the bearing top 30 is inserted into the inner tube 12, the tip protrusion 36 comes into contact with the inner peripheral surface 12 a of the inner tube 12, and the elastic contact portion 34 is pressed in the inner diameter direction to bend. By making the tip protrusion 36 abut against the inner tube 12, the elastic abutment 34 can be easily bent.

  The bearing top 30 in the inner tube 12 is formed between the outer peripheral surface of the base end portion 35 and the inner peripheral surface 12a of the inner tube 12 while relatively changing the amount of elastic deformation of each elastic contact portion 34 in the radial direction. It is possible to change the position in the radial direction (eccentricity) within a clearance range between them. FIG. 6 shows a state where the center line C of the bearing top 30 inserted into the inner tube 12 substantially coincides with the axis of the inner tube 12. In this state, the clearance between the outer peripheral surface of the base end portion 35 and the inner peripheral surface of the inner tube 12 is substantially uniform as a whole, and the three elastic contact portions 34 are bent in a substantially uniform amount in the radial direction. Yes. An imaginary line L1 connecting the fulcrum of elastic deformation in the elastic contact portion 34 (the center in the thickness direction of the connecting portion to the base end portion 35) and the contact position of the tip projection 36 with respect to the inner peripheral surface 12a of the inner tube 12. 6, the inclination angle K1 of the virtual line L1 with respect to the center line C of the bearing top 30 is about 29 degrees in each of the three elastic contact portions 34 in the state of FIG. Note that if K1 <45 ° is set, the sliding operation resistance generated between the elastic contact portion 34 and the inner peripheral surface 12a when the linear actuator 10 performs an expansion / contraction operation is suppressed, and the linear actuator 10 Smooth expansion and contraction can be realized, and the risk of breakage and the like can be reduced by suppressing the load on the bearing top 30.

  FIG. 7 shows a state in which the bearing top 30 is changed in position in the radial direction of the inner tube 12 until the outer peripheral surface of the base end portion 35 comes into contact with the inner peripheral surface 12 a of the inner tube 12. In this state, the amount of bending of the three elastic contact portions 34 becomes non-uniform. FIG. 7 shows two elastic contact portions 34 of the three elastic contact portions 34, one of which is denoted by reference numeral 34A and the other of which is denoted by reference numeral 34B. As can be seen from FIG. 7, the elastic contact portion 34 </ b> A located on the side closer to the inner peripheral surface 12 a of the inner tube 12 is largely bent to the extent that there is almost no protrusion in the outer diameter direction with respect to the base end portion 35. On the other hand, the elastic contact portion 34B located on the side away from the inner peripheral surface 12a of the inner tube 12 has a larger amount of protrusion in the outer diameter direction with respect to the base end portion 35 than in the state of FIG. The amount of bending when the state is used as a reference is small. When the virtual line L2 having the same definition as the previous virtual line L1 is set in the elastic contact portion 34B, the inclination angle K2 of the virtual line L2 with respect to the center line C of the bearing top 30 changes to about 36 degrees in the state of FIG. doing. As can be seen from the comparison with FIG. 5, the elastic contact portion 34B is also pushed and bent toward the inner diameter direction in the state of FIG. 7 as compared with the free state, so that the elastic contact portion 34B is elastically contacted with the inner peripheral surface 12a of the inner tube 12. There is no gap between the tip projection 36 of the contact portion 34B. The bearing top 30 is restricted from further movement in the outer diameter direction (downward movement in the case of FIG. 7) when the outer peripheral surface of the base end portion 35 abuts against the inner peripheral surface 12 a of the inner tube 12. Is done. Therefore, the amount of bending of the elastic contact portion 34 (particularly, the elastic contact portion 34A on the side where the amount of bending from the free state increases) is limited to a predetermined range, and damage to the elastic contact portion 34 due to excessive deformation is prevented. Can be prevented. In particular, even in the state of FIG. 7, the inclination angle K2 of the virtual line L2 of the elastic contact portion 34B with respect to the center line C of the bearing top 30 is K2 <45 °. The effect of suppressing the load is maintained.

  The bearing top 30 having the above configuration has a basic effect of suppressing the shaft runout of the screw shaft 13 by contacting the inner peripheral surface 12a of the inner tube 12. Then, an elastic contact portion 34 is extended rearward from the base end portion 35 at the peripheral edge of the support body 32, and the inner periphery of the inner tube 12 is formed by a tip protrusion portion 36 whose position is different from the support body 32 in the axial direction. By contacting the surface 12a, the contact pressure with respect to the inner tube 12 is appropriately controlled by elastic deformation of the elastic contact portion 34, and the sliding resistance with respect to the inner tube 12 is suppressed as compared with a simple annular resin bearing. Can do.

  The concave portion 33 of the bearing top 30 is a part related to the elastic deformability of the elastic contact portion 34 and also functions as an air hole when the linear actuator 10 expands and contracts. If there is no recess 33 and the bearing top 30 contacts the inner peripheral surface 12a of the inner tube 12 in the entire circumferential direction, the degree of sealing of the space between the inner tube 12 and the screw shaft 13 increases, and the linear actuator 10 expands and contracts. When this occurs, the change in air pressure in the space becomes large, and excessive movement resistance may be exerted. By forming the concave portion 33 that functions as an air hole, such a problem can be prevented.

  The bearing top 30 having a shape in which the elastic contact portion 34 is extended from the peripheral portion of the support 32 is excellent in productivity and durability. In Patent Document 2 described as the prior art, instead of providing the elastic contact portion 34 on the bearing top 30, a thin contact portion is formed by thinning (through hole) at the peripheral portion of the support 32. Although this configuration requires a very high molding accuracy, the load tends to concentrate on both end portions of the through hole that supports the thin contact portion, and breakage easily occurs. On the other hand, the bearing top 30 of the present embodiment has a shape in which the elastic contact portion 34 having a certain thickness is protruded from the support body 32. Therefore, the accuracy control at the time of manufacture is easy, and it is simple and low cost. It can be produced. Since the elastic contact portion 34 has an inclination toward the outer diameter direction as it moves away from the base end portion 35 and moves rearward, a draft is given to the forming die that is released in the direction along the center line C when the bearing top 30 is formed. It is easy to set and is excellent in productivity in this respect. Further, since the entire circumferential region of the elastic contact portion 34 is connected to and supported by the base end portion 35, local load concentration does not occur when the elastic contact portion 34 is bent, and the elastic contact portion 34 Even if 34 undergoes elastic deformation repeatedly, damage is unlikely to occur.

  8 and 9 show a bearing top 130 according to the second embodiment. The bearing top 130 is formed with three recesses 133 and three elastic contact portions 134 on the periphery of the support 132 surrounding the shaft insertion hole 131, and this basic structure is common to the bearing top 30 of the first embodiment. doing. The bearing top 130 is different from the bearing top 30 in that it has an outer surface shape with no step from each elastic contact portion 134 to the base end portion 135 of the periphery of the support body 132 in a free state. That is, the outer peripheral surface of the base end portion 135 and the outer peripheral surface of the elastic contact portion 134 are continuous conical surfaces (partial conical surfaces having no top). The point that the free end of the elastic contact portion 134 is a tip protrusion 136 that protrudes in the outer diameter direction is the same as in the first embodiment, and the tip protrusion 136 is the inner peripheral surface of the inner tube 12. It abuts against 12a. Compared to the bearing top 30 of the previous embodiment, the bearing top 130 configured in this way is in a direction until the base end portion 135 of the peripheral edge of the support body 132 abuts on the inner peripheral surface 12a of the inner tube 12. The allowable movement amount is large, and the base end portion 135 has a shape in which it is difficult to limit the radial movement of the bearing top 130 by contact with the inner peripheral surface 12a. That is, the maximum deflection amount of the elastic contact portion 134 with the connection portion with the base end portion 135 as a fulcrum is large. As described above, the bearing top 30 of the first embodiment improves durability by limiting the amount of bending of the elastic contact portion 34 by the contact between the outer peripheral surface of the base end portion 35 and the inner peripheral surface 12a of the inner tube 12. However, even with the bearing top 130 in which the amount of flexure of the elastic contact portion 134 is increased, the effect of achieving both suppression of the shaft runout of the screw shaft 13 and reduction of the sliding resistance can be obtained.

  The linear actuator 10 provided with the above bearing tops 30 and 130 can be used for various applications. FIG. 10 shows an example in which the linear actuator 10 is mounted on a power trunk lid that opens and closes a trunk lid 40 of a passenger car. The power trunk lid is configured such that an opening 42 formed in the rear portion of the vehicle body 41 can be opened and closed by the trunk lid 40. The trunk lid 40 is pivotally attached to the vehicle body 41 by a pair of hinge members 43 provided in the left-right direction of the vehicle, and can be opened and closed around a pivot 44 of the hinge member 43. The linear actuator 10 is pivotally attached to the side wall surface of the opening 42 of the vehicle body 40 via the fastening hole 19 and pivotally attached to the hinge member 43 of the trunk lid 40 via the fastening hole 20. Yes. With the above configuration, the linear actuator 10 expands and contracts so as to change the interval between the fastening hole 19 and the fastening hole 20 in accordance with the forward / reverse rotation of the motor 15 (FIG. 1), and the trunk lid 40 opens and closes via the hinge member 43. Be operated. As shown in FIG. 10, the trunk lid 40 is opened in a state where the protruding amount of the inner tube 12 from the outer tube 11 is reduced. When the amount of protrusion of the inner tube 12 from the outer tube 11 is increased as shown by a one-dot chain line in FIG. 10, the trunk lid 40 is closed. The final stage of the closing operation of the trunk lid 40 and the locking operation are performed by a closure device provided separately from the linear actuator 10. By applying the linear actuator 10 to such a power trunk lid, the bearing tops 30 and 130 can obtain an effect of reducing abnormal noise and vibration during the opening / closing operation of the trunk lid 40.

  Although the present invention has been described based on the illustrated embodiment, the present invention is not limited to the illustrated embodiment, and can be improved or modified without departing from the gist of the invention. For example, each of the bearing tops 30 and 130 of the embodiment has three elastic contact portions 34 and 134 at substantially equal intervals in the circumferential direction, but the number of elastic contact portions is other than three. Also good.

  The bearing tops 30, 130 of the embodiment are provided with tip protrusions 36, 136 with increased thickness at the free ends of the elastic contact portions 34, 134, and are elastic when contacted with the inner peripheral surface 12 a of the inner tube 12. Although the contact portions 34 and 134 are easily bent, a configuration in which the tip protrusions 36 and 136 are omitted is also possible.

  The bearing tops 30 and 130 of the embodiment are assumed to be molded products of synthetic resin, but the elastic contact portions 34 and 134 can be elastically deformed, and the inner tube 12 and the screw shaft 13 can be smoothly operated. Any material can be selected as the material of the bearing tops 30 and 130 as long as the condition that the condition is not impaired is satisfied. Further, it is possible to form the bearing tops 30 and 130 by changing the material of the support bodies 32 and 132 and the material of the elastic contact portions 34 and 134.

  As described above, the bearing tops 30 and 130 can function in either a form that rotates together with the screw shaft 13 or a form that allows relative rotation with respect to the screw shaft 13.

10 Linear actuator 11 Outer tube 12 Inner tube 12a Inner tube inner peripheral surface 12b Inner tube inner diameter size 13 Screw shaft 14 Drive block 15 Motor 16 Driven gear 17 Nut 18 Socket 19 20 Fastening hole 21 Tip shaft portion 30 130 Bearing top ( Shake prevention member)
31 131 Shaft insertion hole 32 132 Support body 33 133 Recess 34 (34A 34B) 134 Elastic contact portion 35 135 Base end portion 36 136 Tip protrusion 40 Trunk lid 41 Vehicle body 42 Opening portion 43 Hinge member 44 Axis

Claims (4)

A cylindrical cylinder with restricted rotation;
A screw shaft that is rotationally driven and is located in the cylinder;
A nut supported in the cylindrical body, screwed into the screw shaft, and linearly moved in the axial direction of the screw shaft together with the cylindrical body according to the rotation of the screw shaft; and a vibration preventing member attached to an end of the screw shaft ;
Have
The shake prevention member is
A shape that is supported by the end of the screw shaft and has a radial clearance between the cylindrical body and the inner peripheral surface of the cylindrical body, and that faces from the peripheral edge facing the inner peripheral surface of the cylindrical body toward the inner diameter direction. A plurality of recesses having a plurality of recesses in a circumferential direction; and a base end portion located between the plurality of recesses at a peripheral edge of the support body portion, in the base end portion and the axial direction. The position is different and extends to the free end located in the outer diameter direction from the base end, and is slidably abutted against the inner peripheral surface of the cylinder and elastically deformable in the radial direction of the cylinder Elastic contact portion;
The linear actuator characterized by having. 2. The linear actuator according to claim 1, wherein the shake preventing member is movable in a radial direction in the cylindrical body while bending the elastic contact portion, and the base end portion is used as an inner peripheral surface of the cylindrical body. A linear actuator in which the amount of bending of the elastic contact portion is limited by contacting the elastic contact portion. 3. The linear actuator according to claim 1, wherein the free end of the elastic contact portion includes a protrusion protruding in the outer diameter direction, and the protrusion contacts the inner peripheral surface of the cylindrical body. . 4. The linear actuator according to claim 1, wherein the shake preventing member is supported so as to be relatively rotatable with respect to the screw shaft. 5.

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