JP2023110266A - Fixing structure and fixing method - Google Patents

Abstract

To provide a fixing structure which can fix a shaft member more easily while inhibiting removal of the shaft member, and to provide a fixing method.SOLUTION: A fixing structure includes: a fixed object which is formed by using a metallic material and provided with an insertion hole; and a shaft member which is formed by using a metallic material, and has a body and an extension part, which extends from the body in an axial direction and is press-fitted in the insertion hole, in which the extension part has a protruding part protruding in a radial direction and is formed so as to elastically deform to the radial inner side more easily than the body and the protruding part is engaged with the fixed object so as to restrict movement of the extension part in a direction such that the extension part is removed from the insertion hole.SELECTED DRAWING: Figure 3A

Description

The present invention relates to a fixing structure and fixing method.

2. Description of the Related Art A ball screw device in which a piston is fixed to the tip of a screw shaft, for example, is known as an actuator applied to an automobile brake booster or the like (see, for example, Patent Document 1).

JP 2016-014437 A

In the above configuration, the screw shaft is fixed to the piston by press-fitting the tip of the screw shaft into the insertion hole provided in the piston. When press-fitting, it is necessary to manage the press-fit interference and press-fit length so that the screw shaft does not come off, making it difficult to control. In this way, when fixing a metal shaft member such as a screw shaft to a metal fixed object such as a piston, there is a demand for a configuration that allows the work to be performed more easily while suppressing the shaft member from coming off. there is

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing structure and a fixing method that can more easily fix a shaft member while suppressing the shaft member from coming off.

A fixing structure according to an aspect of the present invention is formed using a metal material and includes an object to be fixed provided with an insertion hole, a body portion formed using a metal material, and a main body portion extending axially from the main body portion. and an extending portion press-fitted into the insertion hole, and the extending portion has a projecting portion that projects in the radial direction and is formed so as to be elastically deformed more easily radially inward than the main body portion. and a shaft member in which the protruding portion is engaged with the fixed object so as to restrict movement of the extending portion in a direction of exiting from the insertion hole.

According to this configuration, since the extending portion is formed so as to be elastically deformed more radially inward than the main body portion, it can be easily press-fitted into the insertion hole of the object to be fixed. Further, the extending portion is provided with a projecting portion projecting radially outward, and the projecting portion is engaged with the object to be fixed. Therefore, in a state in which the extending portion is press-fitted into the insertion hole, movement in the direction of exiting the insertion hole is restricted. Therefore, it is possible to prevent the shaft member from coming off without managing the press-fit interference, the press-fit length, and the like. This makes it possible to fix the shaft member more easily while suppressing the shaft member from coming off.

As a preferred aspect of the fixing structure, at least part of the extending portion of the shaft member is formed in a tubular shape. According to this configuration, by forming at least a portion of the extending portion into a tubular shape, it is possible to achieve a configuration that is more likely to be elastically deformed inward in the radial direction than the main body portion.

As a preferred aspect of the fixing structure, the shaft member has a slit extending in the axial direction in at least part of the extending portion. According to this configuration, by providing the slit, it is possible to achieve a configuration that is more likely to be elastically deformed inward in the radial direction than the main body portion.

As a preferred aspect of the fixing structure, the fixed object and the shaft member are arranged in a direction around the axis between the fixed object and the shaft member in a state in which the shaft member is press-fitted into the fixed object. It has a rotation restriction mechanism that restricts the relative rotational movement of the. According to this configuration, by press-fitting the shaft member into the insertion hole, it is possible to suppress rotation of the shaft member while suppressing the shaft member from coming off.

As a preferred aspect of the fixing structure, the rotation restricting mechanism has a slit provided in the shaft member and extending in the axial direction, and a fitting portion provided in the fixed object and fitted into the slit. According to this configuration, it is possible to restrict relative rotational movement between the fixed object and the shaft member in the direction around the axis by using the slit formed in the shaft member.

As a preferred aspect of the fixing structure, the rotation restricting mechanism has a key provided on one of the shaft member and the fixed object, and a key groove corresponding to the key provided on the other. According to this configuration, it is possible to restrict the relative rotational movement of the fixed object and the shaft member in the direction around the axis by using the key and the key groove provided on the shaft member and the fixed object.

As a preferred aspect of the fixing structure, the projecting portion includes a ring member disposed between the object to be fixed and the shaft member for restricting relative movement of the object to be fixed and the shaft member in the axial direction. have. According to this configuration, by using the ring member as the projecting portion, it is possible to more reliably restrict the relative movement of the fixed object and the shaft member in the axial direction.

As a preferred aspect of the fixing structure, the object to be fixed and the shaft member each have an accommodation groove that accommodates a part of the ring member. According to this configuration, the ring member is accommodated in the accommodation groove, so that a state in which both the fixed object and the shaft member are engaged can be formed. As a result, positional displacement in the axial direction of the fixed object and the shaft member can be suppressed.

As a preferred aspect of the fixing structure, the ring member is arranged in a state in which a part thereof is exposed from the accommodation groove, and the exposed portion exposed from the accommodation groove protrudes to the outside of the accommodation groove in the axial direction. be provided. According to this configuration, it is possible to prevent the entire ring member from being buried in the accommodation groove. Therefore, the ring member can be maintained in a state of being locked to both the fixed object and the shaft member.

As a preferred aspect of the fixing structure, the object to be fixed has a contact surface that contacts the main body portion of the shaft member in a state of being press-fitted, and a convex portion provided on a part of the contact surface. The shaft member has a concave portion that is recessed inward in the radial direction at the end portion of the extending portion on the main body side, and the fixed object has the contact surface that is pressed into the main body portion. The contact causes the protrusion to deform and is placed in the recess. According to this configuration, since the convex portion is accommodated in the concave portion by press-fitting, relative movement in the axial direction between the fixed object and the shaft member can be restricted.

As a preferred aspect of the fixing structure, the shaft member is a screw shaft that constitutes a ball screw device. According to this configuration, when fixing the screw shaft to the object to be fixed, it is possible to fix the screw shaft more easily while preventing the screw shaft from coming off.

As a preferred aspect of the fixing structure, the fixed object is a piston. According to this configuration, when fixing the shaft member to the piston, it becomes possible to fix the shaft member more easily while preventing the shaft member from coming off.

As a preferred aspect of the fixing structure, the fixed object is a gear. According to this configuration, when fixing the shaft member to the gear, it becomes possible to fix the shaft member more easily while preventing the shaft member from coming off.

As a preferred aspect of the fixing structure, the shaft member sandwiches the fixed object and the bearing portion between the protruding portion and the main body portion in the axial direction. According to this configuration, it is possible to expand the range of options for the arrangement of the bearings.

A fixing structure according to an aspect of the present invention includes a main body formed using a metal material and an extension extending axially from the main body, wherein the extension protrudes radially. and the extending portion of the shaft member formed so as to be elastically deformable radially inwardly of the main body portion is formed of a metal material and provided with an insertion hole. a press-fitting step of press-fitting into an insertion hole; and a locking step of locking the projecting portion to the fixed object so as to restrict the movement of the extension portion in the direction of exiting the insertion hole.

According to this configuration, since the extending portion is formed so as to be elastically deformed more radially inward than the main body portion, it can be easily press-fitted into the insertion hole of the object to be fixed. Further, by engaging the projecting portion with the object to be fixed, it is possible to easily restrict the movement in the direction of exiting the insertion hole.

According to the aspect of the present invention, it is possible to more easily fix the shaft member while preventing the shaft member from coming off.

FIG. 1 is a cross-sectional view taken in the axial direction of a linear motion actuator using a fixing structure according to this embodiment. FIG. 2 is a diagram showing an example of a fixing structure according to this embodiment. FIG. 3A is a diagram showing the configuration along the AA cross section in FIG. FIG. 3B is a cross-sectional view showing another example of the fixing structure; FIG. 3C is a cross-sectional view showing another example of the fixing structure. FIG. 4 is a perspective view showing an example of a fixing structure. FIG. 5 is a perspective view showing an example of a screw shaft. FIG. 6 is a perspective view showing an example of a piston. FIG. 7 is a process diagram schematically showing an example of the fixing method according to this embodiment. FIG. 8 is a process diagram schematically showing an example of the fixing method according to this embodiment. FIG. 9 is a process diagram schematically showing an example of the fixing method according to this embodiment. FIG. 10 is a perspective view showing another example of the fixing structure. FIG. 11 is a perspective view showing another example of the fixing structure. FIG. 12 is a cross-sectional view showing another example of the fixing structure. FIG. 13 is a cross-sectional view showing another example of the fixing structure. 14 is a cross-sectional view showing a modification of the fixing structure shown in FIG. 13. FIG. FIG. 15 is a cross-sectional view showing another example of the fixing structure. FIG. 16 is a cross-sectional view showing another example of the fixing structure. FIG. 17 is a perspective view showing another example of the fixing structure. 18 is an exploded perspective view of the fixing structure shown in FIG. 17; FIG. FIG. 19 is a perspective view showing another example of the fixing structure. 20 is a side view showing an example of the fixing structure shown in FIG. 19. FIG. FIG. 21 is a diagram showing the configuration along the BB cross section in FIG.

Hereinafter, embodiments of a fixing structure and a fixing method according to the present invention will be described based on the drawings. In addition, this invention is not limited by this embodiment. In addition, components in the following embodiments include those that can be easily replaced by those skilled in the art, or those that are substantially the same, that is, those within the so-called equivalent range. Components disclosed in the following embodiments can be combined as appropriate.

FIG. 1 is a cross-sectional view taken in the axial direction of a linear motion actuator using a fixing structure according to this embodiment. The direct-acting actuator 100 is a brake booster that is mounted on a vehicle and generates hydraulic pressure corresponding to the amount of depression of the brake pedal. As shown in FIG. 1, the linear actuator 100 includes a motor 101, a transmission device 102, a housing 103, a ball screw device 110, and a piston 120.

Hereinafter, the direction parallel to the axis O of the screw shaft 112 of the ball screw device 110 will be referred to as the axial direction. Among the axial directions, the direction in which the piston 120 is arranged as viewed from the nut 111 of the ball screw device 110 is called a first direction X1, and the opposite direction to the first direction X1 is called a second direction X2.

The motor 101 includes a stator (not shown), a rotor (not shown), and an output shaft 101a. The motor 101 is powered by a power supply (not shown) to rotate the rotor and the output shaft 101a. The motor 101 is supported by a housing 103 and has an output shaft 101 a parallel to the screw shaft 112 .

The transmission device 102 includes a first gear 104 fitted to the output shaft 101 a of the motor 101 and a second gear 105 fitted to the outer peripheral side of the nut 111 . The second gear 105 is a gear with a larger diameter than the first gear 104 . Therefore, the transmission device 102 reduces the rotational motion generated by the motor 101 and transmits it to the nut 111 .

The ball screw device 110 includes a nut 111 , a screw shaft 112 and a plurality of balls 113 . The nut 111 has a cylindrical shape with the axis O as the center. An inner peripheral raceway surface 111 a is provided on the inner peripheral surface of the nut 111 . The nut 111 is supported by a bearing 106 fitted on the inner peripheral surface of the housing 103 . Thereby, the nut 111 is rotatable around the axis O of the screw shaft 112 .

The screw shaft 112 is a solid shaft component penetrating the nut 111 . The screw shaft 112 includes a main body portion 114 having an outer peripheral raceway surface 114a on its outer peripheral surface, and an extension portion 115 extending in the first direction X1 from the end face of the main body portion 114 in the first direction X1. . Although not particularly illustrated, the body portion 114 is axially movable and supported by the housing 103 so as not to rotate about the axis O. As shown in FIG. The screw shaft 112 may be provided with a detent member (not shown).

A spiral track is formed between the inner circumferential raceway surface 111a and the outer circumferential raceway surface 114a. A plurality of balls 113 are arranged on this spiral track. When the nut 111 rotates, the inner raceway surface 111a presses the outer raceway surface 114a through the balls 113 in the axial direction. This causes the screw shaft 112 to move in the axial direction. Further, in this embodiment, when the nut 111 rotates in one rotation direction around the axis O, the screw shaft 112 moves in the first direction X1. On the other hand, when the nut 111 rotates in another rotation direction around the axis O, the screw shaft 112 moves in the second direction X2.

The extending portion 115 has a smaller diameter than the body portion 114 . Therefore, an annular stepped surface 114b facing the first direction X1 is provided at the boundary between the extending portion 115 and the main body portion 114. As shown in FIG.

The piston 120 is a columnar component arranged coaxially with the axis O. As shown in FIG. Piston 120 is preferably manufactured by forging, but may be formed by a known processing method such as cutting. The piston 120 is arranged inside the cylinder 107 and near the end in the second direction X2. In addition, although the cylinder 107 of the present embodiment is provided integrally with the housing 103, in the present disclosure, the cylinder 107 and the housing 103 may be separate bodies. The cylinder 107 contains brake fluid (not shown). The piston 120 has a first end face 121 facing the first direction X1 and a second end face 122 facing the second direction X2.

The first end surface 121 is provided with a concave surface 121a recessed in the second direction X2. The concave surface 121 a faces the bottom surface 107 b of the cylinder 107 . A coil spring (not shown) is arranged between the concave surface 121a and the bottom surface 107b. When the piston 120 is pushed in the first direction X1, the piston 120 moves against a coil spring (not shown). Note that the piston of the present disclosure may not be provided with the concave surface 121a.

An insertion hole 123 opening in the second direction X2 is provided in the central portion of the second end face 122 . The extending portion 115 is inserted into the insertion hole 123 . The inner diameter of the insertion hole 123 is slightly smaller than the outer diameter of the extending portion 115, and an interference is provided. Therefore, the piston 120 moves axially together with the screw shaft 112 without being separated from the screw shaft 112 . The opening of the insertion hole 123 is chamfered in a tapered shape.

A portion of the piston 120 that fits with the extending portion 115 (the tubular wall portion surrounding the outer peripheral side of the insertion hole 123) is hereinafter referred to as an inner tubular portion 124. As shown in FIG. As shown in FIG. 1 , the end surface 124 a of the inner cylindrical portion 124 in the second direction X 2 is in contact with the annular stepped surface 114 b of the screw shaft 112 .

The outer peripheral surface of the piston 120 is in slidable contact with the seal member 108 on the inner peripheral side of the cylinder 107 . As a result, brake fluid (not shown) is sealed so as not to flow toward the nut 111 and the screw shaft 112 .

The outer diameter of piston 120 is larger than the outer diameter of nut 111 . A second end surface 122 of the piston 120 is provided with an annular outer cylindrical portion 125 that protrudes in the second direction X2 and surrounds the outer peripheral side of the nut 111 . That is, the outer peripheral surface of the piston 120 is expanded in the second direction X2 by the outer cylindrical portion 125. As shown in FIG. Therefore, even if the piston 120 moves in the first direction X1, the outer cylindrical portion 125 and the sealing member 108 are in sliding contact, and the sealing performance is maintained.

Next, the operation of the linear motion actuator 100 of Embodiment 1 will be described. When the motor 101 is driven, rotational motion is transmitted to the nut 111 via the transmission device 102 . This causes the nut 111 to rotate. Further, when the rotation direction of the nut 111 is one rotation direction around the axis O, the screw shaft 112 moves in the first direction X1. Accordingly, the piston 120 also moves in the first direction X1, increasing the hydraulic pressure of the brake fluid. As a result, the hydraulic pressure of the brake fluid is transmitted to an external device through the through hole 107a.

On the other hand, when the nut 111 rotates about the axis O in another rotation direction, the screw shaft 112 moves in the second direction X2. Accordingly, the piston 120 moves in the second direction X2, and the hydraulic pressure of the brake fluid decreases.

FIG. 2 is a diagram showing an example of the fixing structure 150 according to this embodiment. FIG. 3A is a diagram showing the configuration along the AA cross section in FIG. FIG. 4 is a perspective view showing an example of the fixing structure 150. As shown in FIG. In FIG. 4, the piston 120 is shown partially cut away.

As shown in FIGS. 2 to 4, the fixing structure 150 includes a piston 120, which is an object to be fixed, and a screw shaft 112, which is a shaft member. Piston 120 is formed using a metal material such as an aluminum alloy, for example. The material forming the piston 120 may be another metal material.

Piston 120 has an insertion hole 123 . The insertion hole 123 has an enlarged diameter portion 127 at the end in the first direction X1. The enlarged diameter portion 127 is in a state in which the diameter of the hole is enlarged compared to other portions of the insertion hole 123 . A step surface 128 is formed between the insertion hole 123 and the enlarged diameter portion 127 . The enlarged diameter portion 127 has a longer axial length than the projecting portion 116 .

The screw shaft 112 is formed using a metal material such as chromium molybdenum steel. Other metal materials may be used for the material forming the screw shaft 112 . The screw shaft 112 constitutes the ball screw mechanism 110 together with the nut 111 and balls 113 (see FIG. 6). In addition, as shown in FIG. 4, the nut 111 may be provided with a gear 160 . The screw shaft 112 has a columnar extension 115 at the end in the first direction X1. The extending portion 115 has a projecting portion 116 at its tip. The protruding portion 116 protrudes radially outward from the outer peripheral surface 115 a of the extending portion 115 .

The extending portion 115 has a recess 117 formed from the end face 115b in the first direction X1 toward the second direction X2. The concave portion 117 has a circular shape when viewed from the second direction X2. By providing the recessed portion 117, a portion of the extension portion 115 on the distal end side is formed in a tubular shape. With this configuration, the extending portion 115 is configured to be more elastically deformed inward in the radial direction than the main body portion 114 . The extending portion 115 has a tapered chamfered end on the first direction X1 side.

The extending portion 115 is press-fitted into the insertion hole 123 of the piston 120 . When the extension 115 is press-fitted into the insertion hole 123 , the extension 115 is tightly tightened by the inner cylindrical portion 124 of the piston 120 . Therefore, rattling between the extending portion 115 and the inner cylindrical portion 124 is suppressed. Further, in a state in which the extending portion 115 is press-fitted into the insertion hole 123 , the protruding portion 116 is accommodated in the enlarged diameter portion 127 . In the state in which the projecting portion 116 is accommodated in the enlarged diameter portion 127, the extending portion 115 is elastically deformed radially inward.

In the state in which the projecting portion 116 is accommodated in the enlarged diameter portion 127, the projecting portion 116 is locked to the stepped surface 128 in the second direction X2. This configuration restricts the movement of the extending portion 115 in the second direction X2. In other words, movement of the screw shaft 112 in the direction of exiting from the insertion hole 123 is restricted.

FIG. 3B is a cross-sectional view showing another example of the fixing structure; A fixing structure 150A shown in FIG. 3B has a configuration in which a stepped portion 115c is provided on the extending portion 115 of the screw shaft 112. As shown in FIG. The stepped portion 115c is connected to the end face 114b on the first direction X1 side, and is connected to the end face 114c on the second direction X2 side. Further, the piston 120 has a stepped portion 123c corresponding to the stepped portion 115c. The stepped portion 123c is connected to the end face 124a on the first direction X1 side, and is connected to the end face 124b on the second direction X2 side.

In the fixing structure 150A, the screw shaft 112 is in a state where the stepped portion 115c is press-fitted into the stepped portion 123c. The end face 114c on the screw shaft 112 side and the end face 124b on the piston 120 side are in contact with each other. A gap is formed between the end surface 114b on the screw shaft 112 side and the end surface 124a on the piston 120 side. A gap is formed between the outer peripheral surface 115a on the screw shaft 112 side and the inner peripheral surface 123a surrounding the insertion hole 123 on the piston 120 side.

FIG. 3C is a cross-sectional view showing another example of the fixing structure. A fixing structure 150B shown in FIG. 3C has a configuration in which a convex portion 117A is provided on an end surface 115b of an extension portion 115. As shown in FIG. The convex portion 117A protrudes from the end surface 115b in the second direction X2. The convex portion 117A extends in the second direction X2 from the end face 115b in a columnar shape and has a curved tip in the second direction X2 (a so-called cannonball shape). The diameter of the projection 117A is set so that the protrusion 116 of the screw shaft 112 can be inserted into it. In the fixing structure 150B, the projection 117A is inserted inside the extension 115 of the screw shaft 112. As shown in FIG. By inserting the convex portion 117A inside the extension portion 115, the screw shaft 112 is less likely to come off.

FIG. 5 is a perspective view showing an example of the screw shaft 112. As shown in FIG. As shown in FIG. 5, the extending portion 115 is provided with a slit 115s extending in the axial direction. The slit 115s is formed linearly from the end surface 115b of the extending portion 115 along the second direction X2. A plurality of slits 115s are formed at predetermined intervals in the axial direction. The extending portion 115 is configured to be more elastically deformable on the inner side in the radial direction by providing the slit 115s.

FIG. 6 is a perspective view showing an example of the piston 120. As shown in FIG. As shown in FIG. 6 , a fitting portion 129 is provided on the enlarged diameter portion 127 of the piston 120 . The fitting portion 129 is fitted into the slit 115 s in a state in which the protruding portion 116 is accommodated in the enlarged diameter portion 127 . For example, the fitting portion 129 may be arranged at a position where it fits into all the slits 115s, or may be arranged at a position where it fits with at least one slit 115s. With this configuration, since the piston 120 and the screw shaft 112 are locked in the axial direction, relative rotational movement between the piston 120 and the screw shaft 112 in the axial direction is restricted. In this way, the slit 115s and the fitting portion 129 serve as a rotation restricting member that restricts relative rotational movement between the piston 120 and the screw shaft 112 in the axial direction when the screw shaft 112 is press-fitted into the piston 120. A mechanism 151 is constructed. In the configuration in which the stopper is arranged on the piston 120 , torque can be transmitted between the piston 120 and the screw shaft 112 by providing the rotation restricting mechanism 151 . In addition, for example, a groove extending in the axial direction is provided in the cylinder 107, and a key to be inserted into the groove is provided on the outer peripheral surface of the piston 120. When an anti-rotation structure that restricts rotational movement is provided, the rotation restriction mechanism 151 prevents the piston 120 and the screw shaft 112 from rotating together with the rotation of the nut 111. can.

7 to 9 are process diagrams schematically showing an example of the fixing method according to this embodiment. As shown in FIG. 7 , when fixing the screw shaft 112 to the piston 120 , the extending portion 115 of the screw shaft 112 faces the insertion hole 123 of the piston 120 .

From this state, a force is applied to the screw shaft 112 in the first direction X1 to press-fit the extending portion 115 into the insertion hole 123 (press-fitting step). In the press-fitting step, as shown in FIG. 8, the extending portion 115 is press-fitted into the insertion hole 123 in a state of being elastically deformed in the radial direction. In the present embodiment, the extending portion 115 has a tapered chamfered end on the first direction X1 side, so that the extending portion 115 can be easily inserted into the insertion hole 123 . In addition, since the opening of the insertion hole 123 is chamfered in a tapered shape, the extension part 115 can be easily inserted. Furthermore, since the extending portion 115 is configured to be more elastically deformed radially inward than the main body portion 114, the extending portion 115 can be easily press-fitted.

By continuing to apply force to the screw shaft 112 in the first direction X1, the annular stepped surface 114b comes into contact with the end surface 124a of the inner cylindrical portion, and the projecting portion 116 contacts the enlarged diameter portion 127, as shown in FIG. be accommodated. When the protruding portion 116 is accommodated in the enlarged diameter portion 127 from the insertion hole 123, the hole diameter increases, so that the elastic deformation of the extending portion 115 is reduced. By appropriately adjusting the hole diameter of the expanded diameter portion 127, the extension portion 115 can return from the elastically deformed state (not elastically deformed), or the extension portion 115 can be elastically deformed. It can also be left as is. By accommodating the projecting portion 116 in the enlarged diameter portion 127, the projecting portion 116 is locked to the stepped surface 128 in the second direction X2. Therefore, it is possible to prevent the threaded shaft 112 from moving in the second direction X<b>2 with respect to the piston 120 , that is, the threaded shaft 112 from coming out of the piston 120 .

As described above, the fixing structure 150 according to the present embodiment includes the piston 120 formed using a metal material and provided with the insertion hole 123, the main body portion 114 formed using a metal material, and the main body portion 114 and an extension portion 115 that extends axially from the body portion 115 and is press-fitted into the insertion hole 123 . The extension portion 115 has a projection portion 116 that projects in the radial direction, and is elastically radially inward of the main body portion 114 . A threaded shaft 112 is formed to be easily deformable, and a protruding portion 116 is engaged with the piston 120 so as to restrict the movement of the extending portion 115 in the second direction X<b>2 out of the insertion hole 123 .

According to this configuration, the extending portion 115 is formed so as to be elastically deformed more radially inward than the body portion 114 , so that it can be easily press-fitted into the insertion hole 123 of the piston 120 . A projecting portion 116 projecting radially outward is provided on the extending portion 115 , and the projecting portion 116 is engaged with the piston 120 . Therefore, in a state in which the extending portion 115 is press-fitted into the insertion hole 123 , movement in the direction of exiting from the insertion hole 123 is restricted. Therefore, it is possible to prevent the screw shaft 112 from coming off without managing the press-fit interference, the press-fit length, and the like. This makes it possible to fix the screw shaft 112 more easily while suppressing the screw shaft 112 from coming off.

In the fixing structure 150, the screw shaft 112 has at least a part of the extending portion 115 formed in a cylindrical shape. According to this configuration, by forming at least a portion of the extension portion 115 into a tubular shape, it is possible to achieve a configuration in which the extension portion 115 is more likely to elastically deform inward in the radial direction than the main body portion 114 .

In the fixing structure 150, the screw shaft 112 has an axially extending slit 115s in at least a portion of the extending portion 115. As shown in FIG. According to this configuration, by providing the slit 115 s , it is possible to make the configuration more elastically deformable inward in the radial direction than the main body portion 114 .

In the fixed structure 150, the piston 120 and the threaded shaft 112 are rotated to restrict relative rotational movement between the piston 120 and the threaded shaft 112 in the axial direction when the threaded shaft 112 is press-fitted into the piston 120. It has a regulation mechanism 151 . According to this configuration, by press-fitting the screw shaft 112 into the insertion hole, it is possible to suppress rotation of the screw shaft 112 while suppressing the slipping of the screw shaft 112 .

In the fixing structure 150, the rotation restricting mechanism 151 has a slit 115s provided in the screw shaft 112 and extending in the axial direction, and a fitting portion 129 provided in the piston 120 and fitted into the slit 115s. According to this configuration, the slit 115s formed in the screw shaft 112 can be used to restrict the relative rotational movement between the piston 120 and the screw shaft 112 in the direction around the axis.

In the fixing structure 150, the shaft member is the screw shaft 112 that constitutes the ball screw device. Also, in the fixing structure 150 , the fixed object is the piston 120 . According to this configuration, when fixing the screw shaft 112 to the piston 120 , it becomes possible to fix the screw shaft 112 more easily while suppressing the slipping of the screw shaft 112 .

The fixing method according to the present embodiment has a body portion 114 formed using a metal material and an extension portion 115 extending axially from the body portion 114, and the extension portion 115 projects radially. A piston in which an extension portion 115 of a screw shaft 112 having a portion 116 and formed so as to be easily elastically deformed radially inwardly of a main body portion 114 is formed using a metal material and provided with an insertion hole 123. A press-fitting step of press-fitting 120 into insertion hole 123 , and a locking step of locking projecting portion 116 to piston 120 so as to restrict movement of extending portion 115 in the direction of exiting insertion hole 123 .

According to this configuration, the extending portion 115 is formed so as to be elastically deformed more radially inward than the body portion 114 , so that it can be easily press-fitted into the insertion hole 123 of the piston 120 . Further, by engaging the protruding portion 116 with the piston 120 , it is possible to easily restrict movement in the direction in which the protruding portion 116 is removed from the insertion hole 123 .

10 and 11 are perspective views showing other examples of fixing structures. FIG. 10 shows another example of the screw shaft, and FIG. 11 shows another example of the piston. A screw shaft 212 shown in FIG. The screw shaft 212 is provided with a projecting portion forming a key 215k on the outer peripheral surface 215a of the extending portion 215. As shown in FIG. On the other hand, the piston 220 shown in FIG. 11 is provided with a key groove 223k corresponding to the key 215k on the inner peripheral surface of the insertion hole 223. As shown in FIG. When inserting the extension 215 of the screw shaft 212 into the insertion hole 223 of the piston 220, the key 215k is inserted into the key groove 223k. With this configuration, the key 215k and the key groove 223k are locked in the axial direction. Therefore, the relative rotational movement between the piston 220 and the screw shaft 212 in the direction around the axis is restricted.

Thus, the key 215k and the key groove 223k are rotation restricting mechanisms that restrict relative rotational movement between the piston 220 and the screw shaft 212 in the axial direction when the screw shaft 212 is press-fitted into the piston 220. 251. According to this configuration, the key 215k provided on the screw shaft 212 and the key groove 223k provided on the piston 220 are utilized to restrict the relative rotational movement of the piston 220 and the screw shaft 212 in the direction around the axis. be able to. In addition, the key 215 k may be provided on the projecting portion 216 . Also, in this case, the key groove 223 k may be provided in the enlarged diameter portion 217 .

FIG. 12 is a cross-sectional view showing another example of the fixing structure. As shown in FIG. 12, the fixing structure 350 has a threaded shaft 312, a piston 320, and a ring member 351. As shown in FIG. The fixing structure 350 is provided with an accommodation groove 315b capable of accommodating the ring member 351 in the outer peripheral surface 315a of the extension portion 315 of the screw shaft 312 . The ring member 351 is provided in a state in which a portion in the radial direction is accommodated in the accommodation groove 315b. The ring member 351 can be wholly accommodated in the accommodation groove 315b by being elastically deformed in the radial direction. Ring member 351 includes a retaining ring.

An inner circumferential surface 323 a of the insertion hole 323 is provided with a housing groove 323 b that houses a portion of the outer circumference of the ring member 351 . An outer circumferential surface 315 a of the extending portion 315 is provided with an accommodating groove 315 b that accommodates a portion of the inner peripheral side of the ring member 351 . The ring member 351 is accommodated in the accommodation grooves 323b and 315b, thereby suppressing displacement in the axial direction.

When forming the fixing structure 350, the ring member 351 is arranged in the accommodation groove 315b, and the ring member 351 is elastically deformed to be accommodated in the accommodation groove 315b. do. When the ring member 351 moves in the first direction X1 by press-fitting and reaches the accommodation groove 323b, the elastic deformation is restored and the outer peripheral portion is accommodated in the accommodation groove 323b on the piston 320 side, and the inner peripheral portion is on the screw shaft 312 side. It is housed in the housing groove 315b. As a result, axial movement of the screw shaft 312 and the piston 320 is restricted via the ring member 351 .

Thus, the fixing structure 350 further includes a ring member 351 that is arranged between the piston 320 and the screw shaft 312 and restricts relative movement of the piston 320 and the screw shaft 312 in the axial direction. According to this configuration, by using the ring member 351, relative movement of the piston 320 and the screw shaft 312 in the axial direction can be more reliably restricted.

In addition, in the fixed structure 350, the piston 320 and the screw shaft 312 have accommodation grooves 323b and 315b that accommodate a part of the ring member 351. As shown in FIG. According to this configuration, since the ring member 351 is accommodated in the accommodation grooves 323b and 315b, it is possible to suppress positional displacement of the ring member 351 in the axial direction.

FIG. 13 is a cross-sectional view showing another example of the fixing structure. As shown in FIG. 13, the fixing structure 450 has a configuration in which the extension 415 of the screw shaft 412 axially penetrates the insertion hole 423 of the piston 320 and the projection 416 projects toward the concave surface 421a. An O-ring 452 is arranged between the inner peripheral surface 423 a of the insertion hole 423 and the outer peripheral surface 415 a of the extension portion 415 . The provision of the O-ring 452 ensures sealing performance. At least one of the inner peripheral surface 423 a and the outer peripheral surface 415 a of the insertion hole 423 may be provided with a groove for holding the O-ring 452 .

A ring member 451 is arranged between the protrusion 416 and the concave surface 421a. An outer circumferential surface 415 a of the extending portion 415 is provided with an accommodating groove 415 b that accommodates a part of the inner peripheral side of the ring member 451 . The inner peripheral portion of the ring member 451 is accommodated in the accommodation groove 415b, and the outer peripheral portion abuts against the concave surface 421a, thereby suppressing displacement in the axial direction.

In this manner, the extension 415 of the screw shaft 412 passes through the insertion hole 423 of the piston 420 , and the ring member 451 is locked between the concave surface 421 a of the piston 420 and the accommodation groove 415 b of the screw shaft 412 . With this configuration, it is possible to more reliably prevent the screw shaft 412 from coming off.

14 is a cross-sectional view showing a modification of the fixing structure shown in FIG. 13. FIG. As shown in FIG. 14, the ring member 451A is arranged with a part of the outer peripheral portion exposed from the accommodation groove 415b, and the exposed portion 451s exposed from the accommodation groove 415b protrudes outside the accommodation groove 415b in the axial direction. provided in the state. The ring member 451A is configured such that the exposed portion 451s is so-called caulked.

Thus, in the fixing structure 450, the ring member 451A is arranged in a state where a part thereof is exposed from the accommodation groove 415b, and the exposed portion 451s exposed from the accommodation groove 415b protrudes outside the accommodation groove 415b in the axial direction. provided in According to this configuration, since it is possible to prevent the outer peripheral portion of the ring member 451A from being accommodated in the accommodation groove 415b, the state in which the ring member 451A is locked between the screw shaft 412 and the piston 420 can be more reliably maintained. can be maintained.

15 and 16 are cross-sectional views showing other examples of fixing structures. A fixed structure 550 shown in FIGS. 15 and 16 has a piston 520 and a screw shaft 512 . Piston 520 has an insertion hole 523 , an end face 524 a and a projection 525 . The screw shaft 512 is press-fitted into the insertion hole 523 . The end surface 524a contacts the annular step surface 514a of the screw shaft 512 while the screw shaft 512 is press-fitted. The convex portion 525 is provided on a portion of the end face 524a.

The screw shaft 512 has a body portion 514 , an extension portion 515 and a recessed portion 517 . The extending portion 515 is a portion extending from the main body portion 514 in the second direction X2. The extending portion 515 is press-fitted into the insertion hole 523 of the piston 520 . The body portion 514 has an annular stepped surface 514a at the end in the second direction X2. The annular stepped surface 514 a contacts an end surface (contact surface) 524 a of the inner cylinder portion 524 of the piston 520 when the extension portion 515 of the screw shaft 512 is press-fitted into the insertion hole 523 .

The recessed portion 517 is provided at the end portion of the extending portion 515 on the annular stepped surface 514a side, and has a shape recessed inward in the radial direction. As shown in FIG. 16 , by press-fitting the extending portion 515 into the insertion hole 523 , the convex portion 525 on the side of the piston 520 is elastically deformed and accommodated in the concave portion 517 . By accommodating the convex portion 525 in the concave portion 517, the convex portion 525 is locked to the concave portion 517 in the axial direction.

Thus, in the fixing structure 550, the piston 520 has an end surface 524a that abuts on the body portion 514 of the screw shaft 512 in a press-fitted state, and a convex portion 525 provided on a part of the end surface 524a. The shaft 512 has a recessed portion 517 that is recessed inward in the radial direction at the end portion of the extension portion 515 on the main body portion 514 side. is deformed and accommodated in the concave portion 517 . According to this configuration, the convex portion 525 is elastically deformed and accommodated in the concave portion 517, thereby forming a protruding portion that protrudes radially inward. By press-fitting the convex portion 525 into the concave portion 517 , relative movement in the axial direction between the piston 520 and the screw shaft 512 can be restricted.

FIG. 17 is a perspective view showing another example of the fixing structure. 18 is an exploded perspective view of the fixing structure shown in FIG. 17; FIG. A fixed structure 650 shown in FIGS. 17 and 18 has a gear 620 and a screw shaft 612 . The fixed structure 650 is a structure in which the screw shaft 612 rotates, unlike each structure described above. In fixed structure 650 , the fixed object is gear 620 . The gear 620 is disc-shaped, has a circular insertion hole 621 in the center, and has a plurality of teeth 622 on the outer periphery. The insertion hole 621 passes through the gear 620 in the axial direction. Gear 620 has an inner peripheral surface 623 surrounding insertion hole 621 . A key 623 a is provided on the inner peripheral surface 623 .

The screw shaft 612 has a configuration similar to that of the screw shaft 112 described above, and has a body portion 614 , an extension portion 615 and a projection portion 616 . The extending portion 615 has a cylindrical shape on the distal end side in the first direction X1, and is provided with a slit 615s along the second direction X2 from the end face 615b in the first direction X1. With this configuration, the extending portion 615 is configured to be elastically deformed radially inwardly more easily than the main body portion 614 . In addition, with the extending portion 615 inserted into the insertion hole 621, the key 623a of the inner peripheral surface 623 of the gear 620 is inserted into the slit 615s. This restricts the relative rotation between the screw shaft 612 and the gear 620 in the direction around the axis, forming a so-called detent. The extending portion 615 is press-fitted into the insertion hole 621 and arranged to pass through the insertion hole 621 . The projecting portion 616 is arranged on the opposite side of the gear 620 with respect to the body portion 614 . Protrusion 616 is engaged with first surface 620 a of gear 620 . With this configuration, when the screw shaft 612 is fixed to the gear 620, it is possible to more easily fix the screw shaft 612 while suppressing the screw shaft 612 from coming off.

Thus, in fixed structure 650 , the fixed object is gear 620 . According to this configuration, when the screw shaft 612 is fixed to the gear 620, it is possible to fix the screw shaft 612 more easily while suppressing the screw shaft 612 from coming off.

FIG. 19 is a perspective view showing another example of the fixing structure. 20 is a side view showing an example of the fixing structure shown in FIG. 19. FIG. FIG. 21 is a diagram showing the configuration along the BB cross section in FIG. A fixed structure 750 shown in FIGS. 19 to 21 has a gear 720 , a screw shaft 712 and a bearing portion 730 . A screw shaft 712 constitutes a ball screw device 710 together with a nut 711 and a plurality of balls 713 . The fixed structure 750 is configured such that the screw shaft 712 rotates. The screw shaft 712 has a configuration similar to that of the screw shaft 112 described above, and has a body portion 714 , an extension portion 715 and a projection portion 716 . The extending portion 715 has a cylindrical shape on the distal end side in the first direction X1, and a slit 715s is provided along the second direction X2 from the end face 715b in the first direction X1. Gear 720 has an inner peripheral surface 723 . The inner peripheral surface 723 is provided with a key 723a having the same configuration as the key 623a described above. Further, in a state in which the extending portion 715 is inserted into the insertion hole surrounded by the inner peripheral surface 723, the key 723a of the inner peripheral surface 723 of the gear 720 is inserted into the slit 715s. This restricts the relative rotation between the screw shaft 712 and the gear 720 in the axial direction, forming a so-called detent.

Bearing portion 730 is sandwiched between gear 720 and body portion 714 of screw shaft 712 . That is, the gear 720 and the bearing portion 730 are sandwiched between the projecting portion 716 of the screw shaft 712 and the body portion 714 in the axial direction.

Thus, in the fixing structure 750, the screw shaft 712 sandwiches the gear 720 and the bearing portion 730 between the projecting portion 716 and the body portion 714 in the axial direction. According to this configuration, it is possible to expand the range of options for the arrangement of the bearing portion 730 .

The screw shafts 612 and 712 may have a configuration in which a projecting portion that constitutes a key is provided on the outer peripheral surface of the extending portion 615 . In this case, the gears 620 and 720 are provided with key grooves corresponding to the keys on the inner peripheral surfaces of the insertion holes 623 and 723 . When inserting the extensions 615, 715 of the screw shafts 612, 712 into the insertion holes 623, 723 of the gears 620, 720, the keys are inserted into the key grooves. With this configuration, the key and the keyway are locked in the axial direction, and relative rotational movement in the axial direction between the gears 620, 720 and the screw shafts 612, 712 is restricted.

The technical scope of the present invention is not limited to the above embodiments, and modifications can be made as appropriate without departing from the scope of the present invention. For example, in the embodiment described above, the shaft member is a screw shaft, but the shaft member is not limited to this. The shaft member may have a configuration other than a screw shaft. Similarly, although the piston and gear have been described as examples of fixed objects, they are not limited to these. A fixed object may be a configuration other than a piston and a gear.

O Axis center X1 First direction X2 Second direction 100 Linear actuator 101 Motor 101a Output shaft 102 Transmission device 103 Housing 104 First gear 105 Second gear 106 Bearing 107 Cylinder 107a Through hole 107b Bottom surface 108 Seal member 110, 710 Ball screw device 111, 711 Nut 111a Inner raceway surface 111a, 115b, 124a, 615b, 715b End surface 112, 212, 312, 412, 512, 612, 712 Screw shaft 113, 713, 733 Ball 114, 514, 614, 714 Main body 114a Outer circumference raceway surface 114b Annular step surface 115, 215, 315, 415, 515, 615, 715 Extensions 115a, 215a, 315a, 415a Outer circumference surface 115s, 615s, 715s Slits 116, 316, 416, 616, 716 Projection 117 , 517 recesses 120, 220, 320, 420, 520 piston 121 first end faces 121a, 421a concave face 122 second end faces 123, 223, 323, 423, 523, 621 insertion hole 124 inner cylindrical portion 125 outer cylindrical portion 126 facing surface 127 Expanded diameter portions 128, 328, 428 Step surface 129 Fitting portions 150, 350, 450, 550, 650, 750 Fixing structures 151, 251 Rotation restricting mechanism 215k Key 223k Key grooves 315b, 323b, 415b Accommodating grooves 323a, 423a Inner circumference Surfaces 351, 451, 451A Ring member 451s Exposed portion 452 O-ring 514a Annular stepped surfaces 516, 524 Contact surface 525 Protrusions 620, 720 Gear 620a First surface 622 Teeth 730 Bearing 731 Inner circumference 732 Outer circumference

Claims (14)

a fixed object formed using a metal material and provided with an insertion hole;
It is formed using a metal material and has a body portion and an extension portion that extends axially from the body portion and is press-fitted into the insertion hole, and the extension portion has a projecting portion that projects in the radial direction. The protruding portion is formed so as to be elastically deformable radially inwardly of the main body portion, and the protruding portion is engaged with the fixed object so as to restrict the movement of the extending portion in the direction in which the protruding portion is pulled out of the insertion hole. A fixed structure comprising a fixed shaft member and a fixed structure. The fixing structure according to claim 1, wherein at least part of the extending portion of the shaft member is formed in a tubular shape. The fixing structure according to claim 2, wherein the shaft member has an axially extending slit in at least part of the extending portion. The fixed object and the shaft member restrict relative rotational movement between the fixed object and the shaft member in a direction around the axis when the shaft member is press-fitted into the fixed object. The fixing structure according to any one of claims 1 to 3, comprising a rotation restricting mechanism. 5. The fixing structure according to claim 4, wherein the rotation restricting mechanism has a slit provided in the shaft member and extending in the axial direction, and a fitting portion provided in the fixed object and fitted into the slit. 5. The fixing structure according to claim 4, wherein the rotation restricting mechanism has a key provided on one of the shaft member and the fixed object, and a key groove provided on the other and corresponding to the key. 7. The method according to any one of claims 1 to 6, wherein the projecting portion has a ring member disposed between the object to be fixed and the shaft member to restrict relative movement of the object to be fixed and the shaft member in the axial direction. A fixed structure according to any one of the preceding claims. The object to be fixed and the shaft member each have an accommodation groove that accommodates a part of the ring member,
8. The fixing according to claim 7, wherein the ring member is arranged in a state in which a part thereof is exposed from the accommodation groove, and the exposed portion exposed from the accommodation groove protrudes outside the accommodation groove in the axial direction. structure. The fixed object has an abutment surface that abuts against the main body portion of the shaft member in a press-fitted state, and a convex portion provided on a part of the abutment surface,
the shaft member has a concave portion recessed inward in the radial direction at an end portion of the extending portion on the main body portion side,
9. The object to be fixed is disposed in a state in which the convex portion is deformed and accommodated in the concave portion by press-fitting the contact surface into contact with the main body portion. fixed structure as described above. The fixing structure according to any one of claims 1 to 9, wherein the shaft member is a screw shaft that constitutes a ball screw device. The fixing structure according to any one of claims 1 to 10, wherein the fixed object is a piston. The fixed structure according to any one of claims 1 to 10, wherein the fixed object is a gear. 13. The fixing structure according to claim 12, wherein the shaft member clamps the object to be fixed and the bearing portion between the projecting portion and the main body portion in the axial direction. It has a main body formed using a metal material and an extension extending axially from the main body, the extension having a protruding portion radially extending from the main body. a press-fitting step of press-fitting the extending portion of the shaft member, which is formed so as to be elastically deformable inwardly, into the insertion hole of the fixed object formed using a metal material and provided with the insertion hole;
and a locking step of locking the projecting portion to the object to be fixed so as to restrict movement of the extending portion in a direction of exiting the insertion hole.

Images