阅读说明：本技术 壳体及其制造方法 (Housing and method for manufacturing the same ) 是由 犬塚和也 前田武 贵传名康生 于 2020-02-06 设计创作，主要内容包括：本发明的课题在于,提供一种在内部具有轴部的壳体,且能够削减制造成本的壳体。壳体(1)具有容器(10)和盖(20),上述容器(10)和盖(20)分别构成为在相互对接的状态下在两者之间形成封闭的空间。容器(10)具有朝向盖(20)延伸的轴部(111)。盖(20)具有轴支承部(211),上述轴支承部(211)具有包围轴部(111)的一端部的周壁部(211b)。轴部(111)具有上述一端部被熔融而扩径的扩径部(WD)。(The invention provides a housing having a shaft portion inside and capable of reducing manufacturing cost. The housing (1) has a container (10) and a lid (20), and the container (10) and the lid (20) are respectively configured to form a closed space therebetween in a state of being butted against each other. The container (10) has a shaft portion (111) extending toward the lid (20). The cover (20) has a shaft support portion (211), and the shaft support portion (211) has a peripheral wall portion (211b) surrounding one end portion of the shaft portion (111). The shaft section (111) has a diameter-expanded section (WD) in which the one end is melted and expanded in diameter.)

1. A housing having a first member and a second member each configured to form a closed space therebetween in a state of being butted against each other,

the housing is characterized in that,

the first part has a shaft portion extending towards the second part,

the second member has a shaft support portion having a peripheral wall portion surrounding one end portion of the shaft portion,

the shaft portion has an expanded diameter portion in which the one end portion is melted and expanded in diameter.

2. The housing of claim 1,

the outer peripheral surface of the diameter-expanded portion is welded to the inner peripheral surface of the peripheral wall portion.

3. The housing according to claim 1 or 2,

the outer peripheral edge portions of the first member and the second member are welded to each other over the entire periphery.

4. A method of manufacturing a housing having a first member made of a material that absorbs energy of a laser beam and melts, and a second member made of a material that transmits the laser beam, the first member and the second member being configured to form a closed space therebetween in a state of being butted against each other, the first member having a shaft portion extending toward the second member, the second member having a receiving portion that receives one end portion of the shaft portion,

the method for manufacturing the housing is characterized by comprising the following steps: in a state where the one end portion of the shaft portion is accommodated in the accommodating portion of the second member, a laser beam is irradiated from the second member side toward the top surface of the one end portion of the shaft portion to melt the one end portion of the shaft portion, thereby expanding the diameter of the one end portion of the shaft portion.

Technical Field

The invention relates to a housing and a method of manufacturing the same. In particular, the present invention relates to a sealed case having a shaft portion inside and a method for manufacturing the case.

Background

For example, patent document 1 listed below describes a vehicle door lock device. The vehicle door lock device includes various levers such as a latch and a pawl. The rods are housed in a housing.

The housing has a first part and a second part. The first member is made of a material that absorbs energy of the laser beam and melts, and the second member is made of a material that transmits the laser beam. The first member and the second member are configured to form a space therein in a state of being butted against each other. The first member includes a shaft portion extending toward the second member. The second member includes a housing portion for housing the tip end portion of the shaft portion of the first member (see fig. 19 of patent document 1). The housing portion has a bottom portion (upper bottom portion) and a peripheral wall portion surrounding the shaft portion. The tip of the shaft of the first member is inserted into the receiving portion of the second member, and the top surface of the shaft is brought into contact with the bottom surface of the receiving portion of the second member. The laser beam is irradiated from the second member side toward the top surface of the shaft portion. The laser light passes through the second member to reach the top surface of the shaft portion of the first member. This raises the temperature of the top surface of the shaft portion, and melts the top surface. The heat is transferred to the bottom surface of the receiving portion of the second member, and the bottom surface of the receiving portion is also melted. After that, the irradiation of the laser beam is stopped, and the top surface of the shaft portion and the bottom surface of the housing portion are cooled and solidified. Thus, the top surface of the shaft portion and the bottom surface of the accommodating portion are welded.

Patent document 1: japanese patent laid-open publication No. 2018-9422

The shaft portion in the housing of patent document 1 can be used as a rotation shaft of a lever (or a gear). In this case, when the lever is engaged with another lever and rotated, a load (radial load) applied in a direction (radial direction) perpendicular to the extending direction of the shaft portion is applied to the shaft portion. Here, for example, when the outer diameter of the shaft portion is larger than the inner diameter of the receiving portion, or when the position of the shaft portion and the receiving portion is slightly shifted, a large load may act on the shaft portion when the distal end portion of the shaft portion is inserted into the receiving portion, and the shaft portion may be deformed. For example, there is a fear that the shaft portion is bent. In this case, there is a possibility that the operation of the vehicle door lock device is hindered. For example, there is a fear that the lever is difficult to rotate. Further, the engagement positions of the levers may be displaced from the normal positions, and vibrations, abnormal noise, and the like may occur when the levers rotate.

On the other hand, for example, when the outer diameter of the shaft portion is smaller than the inner diameter of the shaft support portion, the outer peripheral surface of the distal end portion of the shaft portion is not supported by the peripheral wall portion of the shaft support portion, and only the top surface is supported by the bottom portion of the shaft support portion. Therefore, when a load as described above is applied to the shaft portion, the load may be concentrated on the welded portion between the top surface of the shaft portion and the bottom portion of the housing portion, and the welded portion may be sheared and broken. Then, the shaft portion may be largely deformed before the outer peripheral surface of the distal end portion of the shaft portion abuts against the inner peripheral surface of the shaft support portion and is supported, thereby causing an obstacle to the operation of the vehicle door lock device.

Therefore, in the case of patent document 1, it is necessary to maintain the positional accuracy and the outer diameter dimensional accuracy of the shaft portion of the first member and the positional accuracy and the inner diameter dimensional accuracy of the shaft support portion of the second member at high levels, and the manufacturing cost of the case is high.

Disclosure of Invention

The present invention has been made in view of the above-described points, and an object thereof is to provide a housing having a shaft portion inside and capable of reducing manufacturing cost.

In order to achieve the above object, a housing (1) according to the present invention includes a first member (10) and a second member (20), the first member (10) and the second member (20) are respectively configured to form a closed space therebetween in a state of being butted against each other, the first member includes shaft portions (111, 112) extending toward the second member, the second member includes shaft support portions (211, 212), the shaft support portions (211, 212) include peripheral wall portions (211b, 212b) surrounding one end portions of the shaft portions, and the shaft portions include a diameter-enlarged portion (WDs) in which the one end portions are melted and enlarged in diameter.

The present invention also provides a method of manufacturing a case including a first member and a second member, the first member being made of a material that absorbs energy of a laser beam and melts, the second member being made of a material that transmits the laser beam, the first member and the second member being configured to form a closed space therebetween in a state of being butted against each other, the first member having a shaft portion extending toward the second member, the second member having a receiving portion that receives one end portion of the shaft portion, the method including: in a state where the one end portion of the shaft portion is accommodated in the accommodating portion of the second member, a laser beam is irradiated from the second member side toward the top surface of the one end portion of the shaft portion to melt the one end portion of the shaft portion, thereby expanding the diameter of the one end portion of the shaft portion.

In the case according to the present invention, the shaft portion has an enlarged diameter portion whose one end portion is melted and enlarged in diameter. That is, the inner diameter of the shaft support portion is set to be slightly larger than the outer diameter of the shaft portion, and after one end portion of the shaft portion is inserted into the inner circumferential portion, the one end portion of the shaft portion is melted and expanded in diameter, thereby reducing the gap between the outer circumferential surface of the shaft portion and the inner circumferential surface of the shaft support portion. Therefore, even if the machining accuracy (positional accuracy and radial dimensional accuracy) of either or both of the shaft portion and the shaft support portion is slightly low, the shaft portion and the shaft support portion do not interfere with each other when the first member and the second member are brought into abutment with each other. That is, one end portion of the shaft portion is accommodated in the shaft support portion without applying a load such as deformation of the shaft portion. That is, the state in which the shaft portion extends linearly can be maintained. Therefore, the lever, the gear, and the like fitted into the shaft portion smoothly rotate around the shaft portion. Further, it is not easy to hinder the engagement of the member with another member.

When a radial load acts on the shaft portion, the outer peripheral surface of the enlarged diameter portion is supported in contact with the inner peripheral surface of the peripheral wall portion in a state in which the shaft portion is slightly deformed. This can suppress further deformation of the shaft portion. Therefore, there is little possibility that the operation of the device using the housing according to the present invention is hindered.

As described above, according to the present embodiment, even if the machining accuracy (positional accuracy and radial dimensional accuracy) of either or both of the shaft portion and the shaft support portion is slightly low, the operation of the device using the housing is not easily hindered. Therefore, the manufacturing cost of the case can be reduced.

In the case according to one aspect of the present invention, an outer peripheral surface of the enlarged diameter portion is welded to an inner peripheral surface of the peripheral wall portion.

Here, as described above, when the outer peripheral surface of the shaft portion is not supported by the peripheral wall portion of the shaft support portion and only the top surface of the shaft portion and one side surface of the second member are welded, the welded portion may be sheared and broken. In this case, there is a possibility that the operation of the device using the housing may be hindered.

In contrast, in the housing according to the present invention, the outer peripheral surface of the enlarged diameter portion is welded to the inner peripheral surface of the shaft support portion. Therefore, when a radial load acts on the shaft portion during operation of the device using the housing according to the present invention, a compressive load acts on a part of the welded portion. According to this configuration, the welded portion is less likely to be broken than in the case where the top surface of the shaft portion and the one side surface of the second member are welded to each other, that is, are not supported by the peripheral wall portion. Therefore, even if a radial load acts on the shaft portion, the shaft portion is hardly deformed. Therefore, there is no fear that the operation of the device using the housing according to the present invention is hindered.

In the case according to another aspect of the present invention, the outer peripheral edge portions of the first member and the second member are welded to each other over the entire periphery.

The intermediate portion of the sealed case of the present embodiment is supported by the shaft portion. Therefore, the rigidity of the entire housing is relatively high.

Drawings

Fig. 1 is a perspective view of a drive device including a housing according to an embodiment of the present invention.

Fig. 2 is an exploded perspective view of the drive device shown in fig. 1, with the respective components viewed obliquely from the upper right.

Fig. 3 is an exploded perspective view of the drive device shown in fig. 1, with the respective components viewed obliquely from the left and below.

Fig. 4A is a cross-sectional view showing a process of welding the shaft portion to the shaft support portion, and is a cross-sectional view perpendicular to the front-rear direction of the driving device and including the central axis of the shaft portion.

Fig. 4B is a cross-sectional view showing a state where the shaft portion is welded to the shaft support portion through the process shown in fig. 4A, and is a cross-sectional view perpendicular to the front-rear direction of the driving device and including the central axis of the shaft portion.

Fig. 5A is a cross-sectional view showing a step of welding the shaft portion to the shaft support portion in a state where the central axis of the shaft portion is offset from the central axis of the shaft support portion, and is a cross-sectional view perpendicular to the front-rear direction of the drive device and including the central axis of the shaft portion.

Fig. 5B is a cross-sectional view showing a state where the shaft portion is welded to the shaft support portion through the process shown in fig. 5A, and is a cross-sectional view perpendicular to the front-rear direction of the driving device and including the central axis of the shaft portion.

Fig. 6 is a cross-sectional view showing a state where the distal end portion of the shaft portion is expanded in diameter through the step shown in fig. 4A, and is a cross-sectional view perpendicular to the front-rear direction of the driving device and including the central axis of the shaft portion.

Description of the reference numerals

1 … shell; 10 … container; 11 … bottom wall portion; 12 … peripheral wall portion; 20 … cover; 21 … cover plate part; 111. 112 … shaft portion; 111a, 112a … base; 111b, 112b … body portion; 121 … flange portion; 211. 212 … axle support; 211a, 212a … upper bottom; 211b, 212b … peripheral wall parts; c … control device; g1, G2 … gear; an L … laser; an M … electric motor; PG … pinion gear; an S … space; WD … diameter expanding section; an X … drive; y … device.

Detailed Description

A driving device X including a housing 1 (see fig. 1) according to an embodiment of the present invention will be described below. First, an outline of the driving device X will be described. The driving device X drives the device Y (see fig. 2 and 3). The drive device X includes a gear G1, a gear G2, an electric motor M, and a control device C, and these components are housed in the casing 1. In the present embodiment, the device Y is also housed in the housing 1. The rotational driving force of the electric motor M is transmitted to the device Y via gears G1, G2. That is, the device Y has a tooth portion, not shown, that meshes with the gear G2. In the present embodiment, the device Y is housed inside the casing 1, but may be disposed outside the casing 1.

Next, the structure of the driving device X will be explained. As shown in fig. 2 and 3, the housing 1 has a container 10 (first member) and a lid 20 (second member). The container 10 and the lid 20 are made of synthetic resin. The container 10 is made of a synthetic resin material that absorbs energy of the laser beam and melts. The cover 20 is made of a synthetic resin material through which laser light passes.

The container 10 is a box-shaped member having a substantially rectangular parallelepiped shape. In the following description, the depth direction of the container 10 is referred to as the vertical direction. The extending direction of the long side of the container 10 is referred to as the left-right direction, and the extending direction of the short side is referred to as the front-back direction. The container 10 includes a bottom wall portion 11 and a peripheral wall portion 12. The bottom wall 11 is a rectangular plate-like portion extending in the left-right direction. The thickness direction of the bottom wall 11 coincides with the vertical direction. The peripheral wall 12 is provided along the outer peripheral edge of the bottom wall 11, and surrounds the space above the bottom wall 11. The peripheral wall portion 12 is substantially perpendicular to the bottom wall portion 11.

Two shaft portions 111, 112 are formed on the upper surface of the bottom wall portion 11. The shaft portions 111 and 112 are columnar portions extending in the vertical direction. The shaft portions 111 and 112 are located at substantially the center in the front-rear direction of the bottom wall portion 11. The shaft portions 111, 112 are separated in the left-right direction. The shaft portions 111 and 112 have base portions 111a and 112a that slightly protrude upward from the upper surface of the bottom wall portion 11, respectively, and body portions 111b and 112b that extend upward from the center portions of the top surfaces of the base portions 111a and 112a, respectively (see fig. 4A). The outer diameters of the base portions 111a, 112a are slightly larger than the outer diameters of the body portions 111b, 112 b. The protruding height of the base 112a is slightly larger than that of the base 112 a. The outer diameters of the main bodies 111b and 112b are constant from the lower end to the upper end.

The upper end of the peripheral wall portion 12 is located slightly above the upper end of the shaft portions 111 and 112 in the vertical direction. A flange 121 extending outward of the container 10 is formed on the outer peripheral surface of the upper end of the peripheral wall 12.

The cover 20 is a substantially rectangular plate-like member extending in the left-right direction (see fig. 2 and 3). As will be described in detail later, the lid 20 is placed on the upper end surface of the container 10, and the container 10 and the lid 20 are welded to each other. Thereby, a closed space S (closed space) is formed between the container 10 and the lid 20.

The outer shape of the lid 20 is substantially the same as the outer shape of the container 10 in a plan view. In other words, the outer periphery of the lid 20 has substantially the same shape as the outer periphery of the flange portion 121. Shaft support portions 211 and 212 are formed on the lower surface of the cover 20 (see fig. 3 and 4A). The shaft support portions 211 and 212 support the tip end portions (upper end portions) of the shaft portions 111 and 112, respectively, of the container 10, corresponding to the shaft portions 111 and 112. The shaft support portions 211 and 212 are cylindrical portions projecting downward from the lower surface of the cover plate portion 21. The upper ends of the shaft supporting portions 211, 212 are closed, and the lower ends are opened. That is, the shaft support portions 211, 212 have upper bottom portions 211a, 212a and cylindrical peripheral wall portions 211b, 212 b. The protruding height of the shaft supporting part 211 is slightly larger than that of the shaft supporting part 212. In a state where the cover 20 is placed on the upper end surface of the container 10, the positions of the shaft support portions 211 and 212 of the cover plate portion 21 are set so that the center axes of the main body portions 111b and 112b substantially coincide with the center axes of the peripheral wall portions 211b and 212 b. The inner diameters of the peripheral wall portions 211b, 212b are slightly larger than the outer diameters of the body portions 111b, 112b of the shaft portions 111, 112.

The electric motor M is a well-known dc motor. The electric motor M is connected to a control device C described later. The electric motor M is connected to a power supply device, not shown, and electric power is supplied from the power supply device to the electric motor M. The rotation speed and the rotation direction of the electric motor M are controlled by the control device C. A pinion gear PG is attached to a drive shaft of the electric motor M. The electric motor M is fixed to a support portion, not shown, provided at the left end portion of the container 10.

The gear G1 is a spur gear (see fig. 2 and 3). The gear G1 has a base G1a and a tooth G1 b. The base portion G1a is a disk-shaped portion perpendicular to the vertical direction. The outer diameter of the base portion G1a is substantially the same as the outer diameter of the base portion 111a of the shaft portion 111. The tooth portion G1b is disposed above the base portion G1 a. The tooth G1b is a disk-shaped portion perpendicular to the vertical direction. A plurality of teeth are provided on the outer peripheral surface of the tooth portion G1 b. The outer diameter (pitch circle diameter) of the tooth portion G1b is larger than the outer diameter of the base portion G1 a. A through hole TH penetrating in the vertical direction is formed in the center of the gear G1_G1. The main body 111b of the shaft 111 is inserted into the through hole TH_G1And the gear G1 is supported rotatably about the main body 111 b. Tooth G1b of gear G1 meshes with pinion PG.

Gear G2 is a stepped gear. The gear G2 has a first tooth G2a and a second tooth G2 b. The first tooth portion G2a and the second tooth portion G2b are disk-shaped portions. At the first tooth partThe outer peripheral surfaces of G2a and the second tooth portion G2b are provided with a plurality of teeth. The outer diameter of the first tooth portion G2a is substantially the same as the outer diameter of the base portion 112 a. The second tooth G2b is disposed above the first tooth G2 a. The outer diameter (pitch circle diameter) of the second tooth G2b is larger than the outer diameter of the first tooth G2 a. A through hole TH penetrating in the vertical direction is formed in the center of the gear G2_G2. The main body 112b of the shaft 112 is inserted into the through hole TH_G2And the gear G2 is supported rotatably about the main body 112 b. The first tooth G2a of the gear G2 meshes with the tooth G1b of the gear G1. The device Y is fixed to a support portion, not shown, provided at the right end of the container 10. The second tooth G2b of the gear G2 meshes with a tooth portion, not shown, of the device Y.

The control device C is fixed to a support portion (not shown) provided at the right end portion of the container 10 (below the device Y). The control device C is a computer device including an arithmetic device, a storage device (memory), a communication device, and the like. The control device C controls the rotation speed and the rotation direction of the electric motor M in accordance with a predetermined program or a command supplied from an external device (host computer) via a communication device.

The lid 20 is welded to the container 10 as follows. First, the lid 20 is placed on the upper end surface (the upper surface of the flange portion 121) of the container 10 in which the electric motor M, the gear G1, the gear G2, the control device C, and the device Y are housed. In a state where the outer peripheral edge of the cover 20 is arranged along the outer peripheral edge of the flange portion 121, the upper ends of the body portions 111b and 112b of the shaft portions 111 and 112 are respectively housed in the shaft support portion 211 and the shaft support portion 212 (see fig. 4A). Further, the gear G1 is sandwiched between the base 111a and the peripheral wall portion 211b to restrict the movement in the up-down direction thereof, and the gear G2 is sandwiched between the base 112a and the peripheral wall portion 212b to restrict the movement in the up-down direction thereof. In addition, the top surfaces of the main body portions 111b and 112b are separated from the upper bottom portions 211a and 212a in the up-down direction.

Next, the laser light L is irradiated from above the cover 20 to the top surfaces of the main body portion 111b and the main body portion 112b through the upper bottom portion 211a and the upper bottom portion 212 a. The top surfaces of the body 111b and the body 112b absorb the energy of the laser beam L to generate heat, and the portions are melted. The melted portion flows to the outer peripheral sides of the body 111B and the body 112B, enters the gap between the body 111B and the peripheral wall 211B and the gap between the body 112B and the peripheral wall 212B, slightly flows downward, and is cooled and solidified (see fig. 4B). Thus, the distal end portions of the body 111b and the body 112b are expanded in diameter. At this time, the heat of the melting portion is transmitted to the outer peripheral surfaces of the body portions 111b and 112b and the inner peripheral surfaces of the peripheral wall portions 211b and 212b, and these portions are slightly melted. The melted outer peripheral surfaces of the body portions 111b and 112b and the inner peripheral surfaces of the peripheral wall portions 211b and 212b are solidified, whereby the upper end portions of the shaft portions 111 and 112 are welded to the shaft support portion 211 and the shaft support portion 212, respectively.

Next, the laser light L is irradiated from above the lid 20 toward the top surface of the flange portion 121 through the outer peripheral edge portion of the lid 20, and is scanned along the flange portion 121. The upper surface of the flange 121, that is, the portion irradiated with the laser beam L absorbs the energy of the laser beam L to generate heat, and this portion melts. The heat of the melting portion is transferred to the lower surface of the outer peripheral edge portion of the lid 20, and the portion is slightly melted. When the laser beam passes through, the melted portion is cooled and solidified. Thus, the flange 121 is welded to the outer peripheral edge of the lid 20. That is, the sealed case 1 is formed.

When the device Y is disposed outside the housing 1, the rotating shaft of the gear G2 extends outside the housing 1 through a mechanical seal (contact seal device for a rotating shaft), not shown, and this portion is connected to the device Y. Further, a non-contact type coupling (a coupling that transmits a driving force using a magnetic force) may be used.

As described above, the inner diameters of the shaft support portion 211 and the shaft support portion 212 are slightly larger than the outer diameters of the main body portion 111b and the main body portion 112b, respectively. Therefore, even if the machining accuracy (positional accuracy and dimensional accuracy in the radial direction) of one or more of the shaft portion 111, the shaft portion 112, the shaft support portion 211, and the shaft support portion 212 is slightly low, the main body portions 111B and 112B do not interfere with the shaft support portion 211 and the shaft support portion 212, respectively (see fig. 5A and 5B). That is, the main body portion 111b and the main body portion 112b are accommodated in the shaft support portion 211 and the shaft support portion 212, respectively, without applying a load that deforms the main body portion 111b and the main body portion 112 b. That is, the main body 111b and the main body 112b can be maintained in a linearly extended state. Therefore, the friction of the gear G1 and the gear G2 with the main body portion 111b and the main body portion 112b is small, so that the gear G1 and the gear G2 rotate smoothly. Further, the gear G1 and the gear G2 are engaged at regular positions. Therefore, the generation of vibration, abnormal noise, and the like of the drive device X can be suppressed.

If only the top surface of the main body 111b and the upper bottom 211a are welded to each other without the outer peripheral surface of the main body 111b being supported by the peripheral wall 211b of the shaft support 211, the welded portion may be sheared and broken as described above. In this case, the gear G1 may not mesh with the gear G2, and the driving force may not be transmitted.

In contrast, in the present embodiment, the outer peripheral surface of the upper end portion of the body portion 111b is welded to the inner peripheral surface of the peripheral wall portion 211 b. Therefore, when a radial load acts on the body portion 111b during operation of the drive device X, a compressive load acts on a part of the welded portion. According to this configuration, the welded portion is less likely to be broken when the driving device X is operated, as compared with the case where only the top surface of the main body portion 111b is welded to the upper bottom portion 211 a. Therefore, even if a radial load acts on the main body portion 111b, the main body portion 111b is hardly deformed. Therefore, there is no possibility that the operation of the driving device X is hindered.

As described above, according to the present embodiment, even if the machining accuracy (positional accuracy and radial dimensional accuracy) of one or more of the shaft portion 111, the shaft portion 112, the shaft support portion 211, and the shaft support portion 212 is slightly low, there is no possibility that the operation of the drive device X is hindered. Therefore, the manufacturing cost of the case 1 can be reduced.

In the case 1, the outer peripheral edges of the container 10 and the lid 20 are welded to each other over the entire periphery. The substantially central portion of the sealed case 1 is supported by the shaft 111 and the shaft 112. Therefore, the rigidity of the entire housing 1 is relatively high.

In carrying out the present invention, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the object of the present invention.

In the above embodiment, the upper end portions of the body portions 111b and 112b are melted and expanded in diameter, and the outer peripheral surfaces of the expanded-diameter portions WD are welded to the inner peripheral surfaces of the peripheral wall portions 211b and 212b, respectively. However, the outer peripheral surface of the enlarged diameter portion WD may not be welded to the inner peripheral surfaces of the peripheral wall portion 211b and the peripheral wall portion 212 b. That is, the upper end portions of the body 111b and the body 112b may be melted and expanded, and only the gaps between the body 111b and the body 112b and the peripheral wall 211b and the peripheral wall 212b may be reduced (see fig. 6). Accordingly, when a radial load acts on the body 111b and the body 112b, the outer peripheral surface of the enlarged diameter portion is supported in contact with the inner peripheral surfaces of the peripheral wall 211b and the peripheral wall 212b in a state in which the body 111b and the body 112b are slightly deformed. Further deformation of the body portions 111b and 112b is suppressed. Therefore, the operation of the drive device X is hardly hindered.