Motor-driven reciprocation device

Abstract

To provide a motor-driven reciprocation device which can be smoothly assembled and which can perform a smooth reciprocation of a movable part even when a rotational shaft is rotated at high speed.SOLUTION: A motor-driven reciprocation device 10 includes: a rotational shaft 50 having a spiral groove 51 and connected to a motor; and a movable part 70 which engages with the spiral groove 51 and reciprocates in a rotational axis direction of the rotational shaft 50 along with the rotation of the rotational shaft 51. The movable part 70 includes: a groove engagement member 110 having a groove engagement projection 125 that engages with the spiral groove 51 and that moves in a rotational axial direction by the rotation of the rotational shaft 50; a movable body 80 that movably holds the groove engagement member 110 in a direction perpendicular to the rotational axial direction in a range with a predefined play, and that moves in a rotational axial direction integrally with the groove engagement member 110; and a cover 140 that covers a face opposite to the movable body 80 of the groove engagement member 110 and that movably holds the groove engagement member 110 in a direction perpendicular to the rotational axial direction in a range with a predefined play.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a motor-driven reciprocating movement device that reciprocates a moving body by a motor.

Background Art

[0002] Conventionally, for example, as a reciprocating feed mechanism for various detection devices such as slide-type electronic components, or a reciprocating feed mechanism for an optical head in OA equipment, a motor-driven reciprocating movement device driven by a motor has been used.

[0003] This type of motor-driven reciprocating movement device, for example, as shown in Patent Document 1, includes a groove engagement member (91) that engages with a spiral groove (41) of a rotating shaft (40) and moves in the direction of the axis of rotation (B) by the rotation of the rotating shaft (40), a moving body main body (61) that moves in the direction of the axis of rotation (B) integrally with the groove engagement member (91), and a resilient means (111) that disengages the groove engagement member (91) from the spiral groove (41) and allows the rotating shaft (40) to rotate idly when a force is applied to stop the movement of the groove engagement member (91) moving in the direction of the axis of rotation (B).

[0004] In the above conventional motor-driven reciprocating movement device, when a force is applied to further move the moving body main body (61) in the same direction when the moving body main body (61) reaches the terminal position where it can move, in order to cause idling rotation, a resilient means (111) is interposed between the moving body main body (61) and the groove engagement member (91). However, when idling rotation is not necessary, the resilient means (111) is not installed, and a moving body (60) in which the moving body main body (61) and the groove engagement member (91) are integrated is used, and the moving body (60) is configured to reciprocate in the direction of the axis of rotation B as the rotating shaft (40) rotates.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when the moving body (60) in which the moving body main body (61) and the groove engagement member (91) are integrated as described above is used, when assembling this motor-driven reciprocating movement device, due to assembly errors between components, etc., there is a deviation in the assembly position between the spiral groove (41) of the rotating shaft (40) and the groove engagement portion (97), and there was a possibility that the assembly could not be performed smoothly.

[0007] In addition, when the rotating shaft (40) is rotated at high speed, the rotating shaft (40) may bend (deflect). At that time, there may be strong rubbing with the reciprocating moving body (60), generating abnormal noise, and furthermore, there is a possibility that the groove engagement portion (97) may come off from the spiral groove (41) of the rotating shaft (40).

[0008] The present invention has been made in view of the above points, and its object is to provide a motor-driven reciprocating movement device that can be assembled smoothly and can perform smooth reciprocating movement of the moving body even when the rotating shaft is rotated at high speed.

Means for Solving the Problems

[0009] The present invention includes a motor, a rotating shaft having a spiral groove, which is directly connected to the motor or connected to the motor via a rotational power transmission mechanism, a moving body that engages with the spiral groove of the rotating shaft and reciprocates in the axial direction of the rotating shaft as the rotating shaft rotates, the moving body has a groove engagement convex portion that engages with the spiral groove of the rotating shaft, and moves in the axial direction of the rotating shaft by rotating the rotating shaft with the groove engagement convex portion engaged with the spiral groove of the rotating shaft, a groove engagement member, and a moving body main body that movably holds the groove engagement member in a direction intersecting the axial direction of the rotating shaft within a range where the groove engagement convex portion engages with the spiral groove and moves in the axial direction of the rotating shaft integrally with the groove engagement member. It is characterized by being a motor-driven reciprocating movement device. According to the present invention, the moving body is composed of a moving body main body and a groove engaging member, and the groove engaging member is held with respect to the moving body main body in a state having a predetermined play within a range where the groove engaging convex portion engages with the spiral groove. Therefore, even if an assembly error or the like occurs between components when assembling this motor-driven reciprocating device, the assembly of the spiral groove of the rotating shaft and the groove engaging convex portion of the groove engaging member can be smoothly performed without difficulty. Further, even when the rotating shaft is rotated at a high speed and the rotating shaft is bent, strong rubbing does not occur between the rotating shaft and the moving body, there is no possibility of generating abnormal noise, and further, there is no possibility that the groove engaging convex portion comes off from the spiral groove of the rotating shaft.

[0010] In addition to the above features, the present invention further has a cover that covers the surface of the groove engaging member opposite to the moving body main body and holds the groove engaging member movably in a direction intersecting the rotational axis direction within a range where the groove engaging convex portion engages with the spiral groove. According to the present invention, since the surface of the groove engaging member opposite to the moving body main body is covered with a cover, the groove engaging member can be more reliably held in a state having play within a range where the groove engaging convex portion engages with the spiral groove.

[0011] In addition to the above features, the present invention is characterized in that the groove engaging member is installed movably up and down below the moving body main body, and the cover is disposed below the groove engaging member and has a structure that holds the groove engaging member movably in the vertical direction within a range where the groove engaging convex portion of the groove engaging member engages with the spiral groove. According to the present invention, since the groove engaging member installed movably up and down below the moving body main body is held by the cover from below, the groove engaging member can be reliably held in a state having play in the vertical direction.

[0012] In addition to the above features, the present invention is characterized in that the groove engaging member is provided with a rotating shaft insertion hole penetrating the rotating shaft therein, and the groove engaging convex portion engaging with the spiral groove of the rotating shaft is provided on the opposing inner surface of the rotating shaft insertion hole. According to the present invention, since the rotating shaft is passed through the rotating shaft insertion hole provided in the groove engaging member, it is possible to surely prevent the groove engaging member from coming off the rotating shaft.

Effects of the Invention

[0013] According to the present invention, assembly can be performed smoothly, and even when the rotating shaft rotates at high speed, the moving body can perform smooth reciprocating movement.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIGS. 1 to 3 are views showing a motor-driven reciprocating device 10 according to this embodiment. FIG. 1 is a perspective view seen from above, FIG. 2 is a perspective view seen from below, and FIG. 3 is an enlarged schematic cross-sectional view taken along line A-A of FIG. 1. As shown in these figures, the motor-driven reciprocating device 10 includes a motor 30, a rotating shaft 50 driven by the motor 30, and a moving body 70 that reciprocates in the axial direction L of the rotating shaft 50 as the rotating shaft 50 rotates. Further, in this embodiment, as shown by the dotted line in FIG. 3, an operating device 200 such as a slide-type electronic component operated by the reciprocating movement of the moving body 70 is installed on the motor-driven reciprocating device 10. In the following description, "above" refers to the direction of viewing from the moving body 70 toward the operating device 200 side, and "below" refers to the opposite direction. Also, "front" refers to the direction of viewing the moving body 70 from the motor 30, and "rear" refers to the opposite direction. Also, the direction P orthogonal to the axial direction L in the horizontal plane is defined as the "width direction" or "left-right direction". Also, the vertical direction is defined as Q. However, these directions are not intended to limit the directions when using the motor-driven reciprocating device 10.

[0016] FIG. 4 is an enlarged perspective view of the main part in a state where the members (the moving body main body 80, the groove engagement member 110, and the cover 140 described below) constituting the moving body 70 are removed from the motor-driven reciprocating device 10 shown in FIG. 2. As shown in this figure and FIGS. 1 to 3, the operating device 200 is mounted on a mounting plate 210 made of a metal plate, but since it is not the main part of the present invention, its detailed description is omitted. The mounting plate 210 is configured by bending the left and right sides of a main plate 211 made of a substantially rectangular long metal plate upward to form side plates 213 and 215, and bending the front and rear sides of the main plate 211 downward to form end plates 217 and 219. A pair of arm insertion holes 221 and 223 are formed in the main plate 211 parallel to its longitudinal direction (the axial direction L).

[0017] A moving body mounting member 230 is attached to the lower surface of the main board 211 by fixing means (not shown). The moving body mounting member 230 is a synthetic resin plate that is substantially flat and rectangular and elongated in the rotational axis direction L. Rail portions 231, 231 extending in the rotational axis direction L are provided on both the left and right sides of the moving body mounting member 230. These rail portions 231, 231 hold the locking portions 86, 86 of the rail locking portions 85, 85 of the moving body main body 80 described below on their upper surfaces and are slidably held in the rotational axis direction L.

[0018] As described above, the motor-driven reciprocating movement device 10 includes a motor 30, a rotating shaft 50, and a moving body 70. Here, one end surface of the motor 30 is fixed to the outer surface of one end face plate 217 of the mounting plate 210. The drive shaft of the motor 30 passes through the end face plate 217 and protrudes inside thereof, and its tip is connected to the rotating shaft 50 via a resin connecting member 35. The other end of the rotating shaft 50 is rotatably supported by the other end face plate 219 of the mounting plate 210 via a synthetic resin shaft holding member 225.

[0019] The rotating shaft 50 is a lead screw configured by forming a spiral groove 51 over the entire length of its outer peripheral surface. One end of the rotating shaft 50 is connected to the drive shaft of the motor 30 via the connecting member 35 as described above, and the other end of the rotating shaft 50 is rotatably held by the end face plate 219 of the mounting plate 210 via the shaft holding member 225. Note that instead of directly connecting to the motor 30 as in this embodiment, the rotating shaft 50 may be configured to be connected to the motor 30 via a rotational power transmission mechanism.

[0020] FIG. 5 is an exploded perspective view of the moving body main body 80, the groove engaging member 110, and the cover 140 that constitute the moving body 70 as viewed from below, and FIG. 6 is an exploded perspective view of these moving body main body 80, the groove engaging member 110, and the cover 140 as viewed from above. The rotating shaft 50 is further shown in FIG. 5.

[0021] The moving body main body 80 is a molded product of synthetic resin, and includes a substantially rectangular flat main body base 81, four guide holes 83 penetrating vertically formed near the center of the main body base 81, four rail locking portions 85 protruding upward from the left and right outer side positions of each guide hole 83, a pair of arm portions 87 protruding upward from the left and right outer side positions of the left and right rail locking portions 85, and three protrusions 91 protruding downward from the vicinity of both left and right sides of the lower surface of the main body base 81.

[0022] The four guide holes 83 are formed as long holes (holes in a shape where two semi - circles are connected by a rectangle) that are long in the width direction P. The width dimension (diameter of the semi - circle) of the guide hole 83 is formed to be substantially the same as the outer diameter dimension of the guide protrusion 115 provided on the groove engagement member 110 described below.

[0023] The four rail locking portions 85 are arranged in pairs left and right along the rotation axis direction L, and each is substantially rectangular flat plate - shaped and has its upper end side bent substantially at a right angle toward the inside (center side). The bent tip - side portion is referred to as the locking portion 86.

[0024] The arm portion 87 is substantially flat plate - shaped and protrudes to a position higher than the rail locking portion 85.

[0025] The groove engagement member 110 is a molded product of synthetic resin, and is configured by providing a substantially rectangular rotation shaft insertion and holding portion 113 below a substantially rectangular flat plate - shaped member main body portion 111.

[0026] At positions on the upper surface of the member main body portion 111 that face the respective guide holes 83 of the moving body main body 80, substantially columnar guide protrusions 115 to be inserted into the respective guide holes 83 are provided protruding. Further, on both side edges in the rotational axis direction L of the member main body portion 111, a pair of protruding portions 117 facing upward are provided. The dimension between the opposing inner surfaces of the pair of protruding portions 117 is formed to be substantially the same as the length dimension between both end sides in the rotational axis direction L of the moving body main body 80. That is, if each guide protrusion 115 of the groove engagement member 110 is inserted into each guide hole 83 of the moving body main body 80 and the moving body main body 80 is inserted between the pair of protruding portions 117 of the groove engagement member 110, the groove engagement member 110 can reciprocate in the left - right direction P with respect to the moving body main body 80 by the dimension by which each guide hole 83 is an elongated hole. At this time, by the engagement between the guide hole 83 and the guide protrusion 115, and the engagement between both end sides in the rotational axis direction L of the moving body main body 80 and the pair of protruding portions 117, the left - right reciprocating movement of the groove engagement member 110 is guided.

[0027] The rotation shaft insertion holding portion 113 is formed in a substantially square - cylindrical shape, and is configured by providing a rotation shaft insertion through - hole 121 that penetrates in the rotational axis direction L and through which the rotation shaft 50 is inserted inside. On the opposing surfaces on the rotation shaft insertion through - hole 121 side of the left and right side walls 123 of the rotation shaft insertion holding portion 113, groove engagement convex portions 125 that engage with the spiral groove 51 of the rotation shaft 50 are provided. The groove engagement convex portions 125 are constituted by two parallel and linear protrusions that are inclined obliquely in the up - down direction Q. The left and right side walls 123 of the rotation shaft insertion holding portion 113 are connected at predetermined intervals by three rod - shaped connecting portions 127 between their lower end sides. On the surfaces of the lower surfaces of the pair of left and right side walls 123 where the connecting portions 127 are not provided, four cover contact portions 129 formed of small protrusions are provided. Further, recesses 131 are respectively formed at the portions of the connecting portions 127 on both end surfaces in the rotational axis direction L of the rotation shaft insertion holding portion 113. These recesses 131 are formed so that when the groove engagement member 110 moves to the end in the rotational axis direction L by the rotation shaft 50, the surface of this connecting portion 127 does not come into contact with other members (connecting member 35 or shaft holding member 225).

[0028] The cover 140 is a molded product of synthetic resin, and cover side walls 143 are erected upward from both left and right sides of a substantially flat plate-shaped cover bottom wall 141, and further provided with mounting portions 145 protruding in a plate shape from the upper end sides of the cover side walls 143 toward both left and right outer sides. Here, the space surrounded by the cover bottom wall 141 and both cover side walls 143 is used as a groove engagement member storage portion 147.

[0029] A through hole 149 extending in the left-right direction P is formed in the central portion of the cover bottom wall 141. The through hole 149 is formed in a shape and dimension for inserting the central connecting portion 127 of the groove engagement member 110 with a predetermined gap. Protrusion portions 151 in a substantially rectangular plate shape project from three opposed positions on the opposed inner surfaces of the cover side walls 143. The width dimension between the guide portions 151A which are the tip sides of the opposed protrusion portions 151 is such that the rotation axis insertion and holding portion 113 of the groove engagement member 110 is inserted with a predetermined gap. Also, a step portion 153 is formed between the upper end side 151B of each protrusion portion 151 and the upper surface of the mounting portion 145, and the height dimension of this step portion 153 is formed to be slightly larger than the thickness dimension of the member main body portion 111 of the groove engagement member 110. Also, the width dimension between the opposed surfaces inside the left and right mounting portions 145 is also formed to be slightly larger than the width dimension of the member main body portion 111 of the groove engagement member 110. Also, the length dimension of the cover 140 in the rotation axis direction L is such that the cover 140 is inserted inside the connecting portions 127 on both sides of the groove engagement member 110. Also, at positions of the mounting portion 145 facing each protrusion 91 of the moving body main body 80, three protrusion insertion portions 155 each formed of a through hole for inserting each protrusion 91 and protruding its tip to the lower surface side are formed.

[0030] Next, to assemble the above motor-driven reciprocating movement device 10, first, the groove engagement member 110 is installed on the lower surface side of the moving body main body 80. At this time, while inserting each guide protrusion 115 of the groove engagement member 110 into each guide hole 83 of the moving body main body 80, the main body base portion 81 is slidably inserted between a pair of protrusion portions 117.

[0031] Next, cover the groove engagement member 110 from below with the cover 140 and store the groove engagement member 110 in the groove engagement member storage portion 147. Bring the upper surface of the attachment portion 145 of the cover 140 into contact with the lower surface of the main body base portion 81 of the moving body main body 80. At this time, insert each protrusion 91 of the main body base portion 81 into each protrusion insertion portion 155 of the cover 140, and further caul and fix the tip of the protrusion 91 protruding from the lower surface of the attachment portion 145. At this time, the connecting portion 127 at the center of the lower surface of the groove engagement member 110 is inserted into the through hole 149 of the cover 140, and the connecting portions 127 on both the left and right sides are arranged at positions protruding to the outside from both ends in the rotation axis direction L of the cover 140. As a result, the cover contact portion 129 of the groove engagement member 110 abuts on the upper surface of the cover bottom wall 141. At this time, as shown in FIG. 3, a vertical gap S1 is formed between the upper surface of the member main body portion 111 of the groove engagement member 110 and the lower surface of the main body base portion 81 of the moving body main body 80, whereby the groove engagement member 110 can move up and down in the Q direction by the amount of the gap S1. The dimension of this gap S1 is set to a dimension that allows the groove engagement member 110 to move in the vertical direction within a range that can maintain the state in which the groove engagement convex portion 125 is engaged with the spiral groove 51 of the rotation shaft 50, as described below. Since the through hole 149 is provided in the central portion of the cover bottom wall 141 as described above and the connecting portion 127 at the center of the lower surface of the groove engagement member 110 is inserted therethrough, the height dimension of the cover 140 can be suppressed.

[0032] Also, with respect to the moving body main body 80, the groove engagement member 110 can move in the left - right direction P by a predetermined dimension by inserting the guide protrusions 115 into the long - oval guide holes 83. To ensure this movement, a gap is also provided between the groove engagement member 110 and the cover 140. That is, as described above, gaps are provided between the left and right guide portions 151A and the left and right attachment portions 145 of the cover 140 so that the groove engagement member 110 can move in the left - right direction by a predetermined dimension. These gap dimensions are set to dimensions that allow the groove engagement member 110 to move in the left - right direction within a range that can maintain the state in which the groove engagement convex portion 125 is engaged with the spiral groove 51 of the rotation shaft 50, as described below.

[0033] Then, the rotary shaft 50 is inserted into the rotary shaft insertion hole 121 of the groove engagement member 110, and while the spiral groove 51 is screwed into the groove engagement convex portion 125, it is penetrated. Next, one end of the rotary shaft 50 is fixed to the connecting member 35 on the motor 30 side, and the other end is rotatably supported by a shaft holding member 225 attached to the inner surface of the end face plate 219 of the mounting plate 210.

[0034] At this time, the pair of arm portions 87 of the moving body main body 80 penetrate through the pair of arm insertion holes 221 and 223 of the mounting plate 210 and are locked to an arm portion locking portion (not shown) of the operating device 200.

[0035] When assembling the motor-driven reciprocating movement device 10 as described above, as described above, since the groove engagement member 110 has play (rattling) with a predetermined gap in the vertical and horizontal directions Q and P between the moving body main body 80 and the cover 140, when assembling this motor-driven reciprocating movement device 10, even if there is a deviation in the assembly position between the spiral groove 51 of the rotary shaft 50 and the groove engagement convex portion 125 of the groove engagement member 110 due to assembly errors between components, the assembly can be performed smoothly. Needless to say, the above assembly procedure is an example, and it may be assembled using various other different assembly procedures.

[0036] In the motor-driven reciprocating movement device 10 assembled as described above, when the motor 30 is driven, the rotary shaft 50 rotates, the groove engagement member 110 screwed thereto moves in the rotary axis direction L, and the entire moving body 70 integrated with the groove engagement member 110 moves.

[0037] Accordingly, the arm portion 87 of the moving body main body 80 moves inside the operating device 200 and drives it. Conversely, by driving the arm portion 87 of the moving body main body 80, the rotary shaft 50 can be rotationally driven and this rotational force can be utilized.

[0038] Here, for example, even if the rotating shaft 50 is bent (deflected) due to reasons such as the high rotational speed of the rotating shaft 50, as described above, since there is play (rattling) with a predetermined gap in the vertical and horizontal directions Q and P between the groove engaging member 110 and the moving body main body 80 and the cover 140, it can move easily in the deflected direction, ensuring smooth movement of the moving body 70 without generating abnormal noises. Furthermore, there is no risk that the groove engaging convex portion 125 of the groove engaging member 110 will come off from the spiral groove 51 of the rotating shaft 50.

[0039] Since the surface of the groove engaging member 110 opposite to the moving body main body 80 is covered with the cover 140, the groove engaging member 110 can be more reliably held in a state with play within the range where the groove engaging convex portion 125 engages with the spiral groove 81. Furthermore, since the groove engaging member 110 installed movably up and down below the moving body main body 80 is held by the cover 140 from its lower side, the groove engaging member 110 can be more reliably held in a state with play in the vertical direction. Also, since the rotating shaft 80 passes through the rotating shaft insertion hole 121 provided in the groove engaging member 110, the risk that the groove engaging member 110 will come off from the rotating shaft 80 can be reliably prevented.

[0040] By the way, in the above motor-driven reciprocating movement device 10, the groove engaging member 110 rattles within the cover 140. However, among the lower surface of the groove engaging member 110, only the portion of the cover contact portion 129 formed by four small protrusions comes into point contact with the upper surface of the cover bottom wall 141. Therefore, the contact resistance can be reduced compared to the case where the two are in surface contact, and a contact state with low resistance can be maintained. Also, among the left and right side surfaces of the rotating shaft insertion holding portion 113 of the groove engaging member 110, only the portions of the three linear guide portions 151A on each of the left and right sides come into line contact with the cover side wall 143 side. Therefore, the contact resistance can be reduced compared to the case where the two are in surface contact, and a contact state with a low resistance value can be maintained.

[0041] Also, in the above-described embodiment, at the upper part of the groove engagement member 110, the left and right member main bodies 111 are connected by a pair of protrusions 117 in a direction orthogonal to the rotation axis direction L of the rotation shaft 50, thereby ensuring the strength of the groove engagement member 110. However, if the strength of the groove engagement member 110 is maintained by other parts, it is not necessarily required to be connected by the protrusions 117.

[0042] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the technical idea described in the claims, the specification, and the drawings. Note that any shape, structure, or material that is not directly described in the specification and the drawings is within the scope of the technical idea of the present invention as long as it exhibits the functions and effects of the present invention. For example, the operating device 200 is not limited to a slide-type electronic component, and may be used as various other detection devices or a reciprocating feed mechanism for an optical head in various OA devices. In addition, the embodiments described above and shown in the respective figures can be combined with each other's description contents as long as there is no contradiction in their purposes and configurations. Further, the description contents of the above description and each figure can be independent embodiments even if they are a part of them, and the embodiments of the present invention are not limited to one embodiment that combines the above description and each figure.

Explanation of Reference Numerals

[0043] 10 Motor-driven reciprocating movement device 30 Motor 50 Rotation shaft 51 Helical groove L Rotation axis direction 70 Movable body 80 Movable body main body 110 Groove engagement member 121 Rotation shaft insertion hole 125 Groove engagement convex portion 140 Cover

Claims

1. A motor, a rotating shaft having spiral grooves and directly connected to the motor or connected to the motor via a rotational power transmission mechanism, a moving body engaged with the spiral grooves of the rotating shaft and reciprocating in the direction of the rotational axis of the rotating shaft as the rotating shaft rotates, characterized by comprising: the moving body has a groove engagement convex portion engaged with the spiral groove of the rotating shaft, and a groove engagement member that moves in the direction of the rotational axis by rotating the rotating shaft in a state where the groove engagement convex portion is engaged with the spiral groove of the rotating shaft, holds the groove engagement member movably in a direction intersecting the rotational axis direction within a range where the groove engagement convex portion engages with the spiral groove, and has a moving body main body that moves in the rotational axis direction integrally with the groove engagement member, a motor-driven reciprocating device.

2. The motor-driven reciprocating device according to claim 1, further comprising a cover that covers a surface of the groove engagement member opposite to the moving body main body and holds the groove engagement member movably in a direction intersecting the rotational axis direction within a range where the groove engagement convex portion engages with the spiral groove.

3. The motor-driven reciprocating device according to claim 2, wherein the groove engagement member is installed below the moving body main body so as to be vertically movable, and the cover is disposed below the groove engagement member and has a structure that holds the groove engagement member vertically movably within a range where the groove engagement convex portion of the groove engagement member engages with the spiral groove.

4. The motor-driven reciprocating device according to claim 1, wherein the groove engagement member is provided with a rotating shaft insertion hole penetrating the rotating shaft therein, and the groove engagement convex portion engaged with the spiral groove of the rotating shaft is provided on opposite inner surfaces of the rotating shaft insertion hole.

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