TWI841380B - Spindle steering device and its clutch mechanism - Google Patents

Abstract

A clutch mechanism of a spindle steering device includes a housing unit, a piston unit and a clutch unit. The piston unit includes a fixed seat and a piston member surrounding the fixed seat and defining a chamber together with the fixed seat. The clutch unit includes a first clutch member, a connecting assembly arranged between the piston member and the first clutch member, a second clutch member facing the first clutch member, and a limit member. When the first clutch member is located at a separation position relative to the second clutch member, the first clutch member is far away from the second clutch member. When the first clutch member is located at a locking position, the first clutch member is adjacent to the second clutch member and is coupled to the second clutch member and the limit member. The piston structure formed by the piston member surrounding the fixing seat has a smaller volume, so that the clutch unit and the piston unit can be compactly combined, greatly reducing the size of the main shaft steering device.

Description

Spindle steering device and its clutch mechanism

The present invention relates to a shaft seat for mounting a spindle of a machine tool, and in particular to a spindle steering device and a clutch mechanism thereof.

A conventional machine tool includes a shaft seat, a spindle mounted on the shaft seat, and a motor mounted on the shaft seat and capable of driving the spindle to rotate around a rotation axis.

According to different processing requirements, the spindle can be a drill bit, milling cutter or grinding wheel to perform drilling, cutting or grinding. However, the machine tool can only process in the direction of the rotating axis or the direction of rotation around the rotating axis. If the user needs to process in the direction of other rotating axes or the direction of rotation around other rotating axes, he needs to select and replace different machine tools, which is very inconvenient and costly to use.

Therefore, the purpose of the present invention is to provide a spindle steering device and a clutch mechanism thereof that can improve at least one of the above-mentioned shortcomings.

Therefore, the clutch mechanism of the spindle steering device of the present invention includes a housing unit, a piston unit, and a clutch unit.

The housing unit defines a containing space. The piston unit includes a fixed seat arranged in the containing space, and a piston member surrounding the fixed seat and defining a chamber together with the fixed seat, and the piston member can be pushed by a working fluid injected into the chamber to move relative to the fixed seat in an axial direction. The clutch unit includes a first clutch member arranged in the containing space, a connecting assembly arranged between the piston member and the first clutch member, a second clutch member arranged in the containing space and facing the first clutch member in the axial direction, a limiting member located in the containing space and fixed to the housing unit, and a reset member arranged between the first clutch member and the housing unit.

The reset member has elasticity to make the first clutch member always move toward the second clutch member, and the piston member can drive the connecting assembly to move along the axial direction, so that the connecting assembly drives the first clutch member away from the second clutch member. The first clutch member can be switched between a separation position and a locking position relative to the second clutch member. When the first clutch is located at the separation position, the first clutch is away from the second clutch, and the second clutch can rotate relative to the housing unit around a rotation axis parallel to the axial direction. When the first clutch is located at the locking position, the first clutch is adjacent to the second clutch and coupled to the second clutch and the limiter. The limiter restricts the first clutch from rotating around the rotation axis, and the first clutch restricts the second clutch from rotating around the rotation axis.

The spindle steering device of the present invention includes a clutch mechanism, a mounting seat, a steering head, and a driving unit.

The clutch mechanism includes a housing unit, a piston unit, and a clutch unit. The housing unit defines a housing space. The piston unit includes a fixed seat arranged in the housing space, and a piston member surrounding the fixed seat and defining a chamber together with the fixed seat, and the piston member can be pushed by a working fluid injected into the chamber to move relative to the fixed seat along an axial direction. The clutch unit includes a first clutch member arranged in the housing space, a connecting group arranged between the piston member and the first clutch member, a second clutch member arranged in the housing space and facing the first clutch member along the axial direction, a limiting member located in the housing space and fixed to the housing unit, and a reset member arranged between the first clutch member and the housing unit.

The reset member has elasticity to make the first clutch member always move toward the second clutch member, and the piston member can drive the connecting assembly to move along the axial direction, so that the connecting assembly drives the first clutch member away from the second clutch member. The first clutch member can be switched between a separation position and a locking position relative to the second clutch member. When the first clutch is located at the separation position, the first clutch is away from the second clutch, and the second clutch can rotate relative to the housing unit around a rotation axis parallel to the axial direction. When the first clutch is located at the locking position, the first clutch is adjacent to the second clutch and coupled to the second clutch and the limiter. The limiter restricts the first clutch from rotating around the rotation axis, and the first clutch restricts the second clutch from rotating around the rotation axis.

The mounting seat is arranged on a side of the second clutch opposite to the first clutch. The steering head is arranged on a side of the mounting seat opposite to the second clutch and is used for the main shaft to be arranged. The driving unit is arranged in the accommodating space and is used to drive the mounting seat to rotate.

The effect of the present invention is that the volume of the piston structure formed by the piston member surrounding the fixing seat is relatively small, so that the clutch unit, the piston unit and the drive unit can be compactly combined, reducing the movable space required when the mounting seat rotates, and greatly reducing the axial size and radial size of the main shaft steering device.

10: Clutch mechanism

1: Shell unit

11: Storage space

12: Shell body

13: convex seat

131: First side

132: Second side

133: Ring groove

2: Piston unit

21: Fixed seat

211: Seat Body

213: Outer surface

214: Inner Surface

215: Perforation

216: End face

217: Runner

218: Liquid inlet

219: Liquid outlet

212: convex ring

22: Piston parts

221: Piston body

222: Surrounding part

223: convex part

23: First O-ring

24: Second O-ring

25: Chamber

3: Housing unit

31: Base wall

311: Inner wrap

312: Open mouth

313: Outer perimeter

314: Injection channel

32: Wall

321: Gap

33: Oil seal O-ring

4: Clutch unit

41: First clutch

42: Connection set

421:Fixers

422: Shoulder screw

43: Second clutch

44: Limiting parts

441: Fixed gear ring

442: Positioning pin

45: Reset piece

451:Compression spring

5: Mounting seat

51: Ring seat

52: Ring plate

53: Adapter

54: First fixing screw

55: Second fixing screw

6: Turn your head

61:Connection part

62: Installation Department

621: Installation space

7: Drive unit

71: Driving motor

72: Transmission parts

73: Reducer

8: Main axis

81: Spindle motor

82: Grinding wheel

L1: Rotation axis

L2: Center axis

D: Axial

θ: Turning angle

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: FIG. 1 is an embodiment of the spindle turning device of the present invention and a partial three-dimensional exploded view of a spindle; FIG. 2 is a three-dimensional exploded view of the embodiment; FIG. 3 is a partial three-dimensional exploded view of the embodiment; FIG. 4 is a cross-sectional view of the embodiment, showing a first clutch member in a separation position relative to a second clutch member; FIG. 5 is an incomplete cross-sectional view taken along the line V-V in FIG. 4; FIG. 6 is an incomplete cross-sectional view taken along line VI-VI in FIG. 5; FIG. 7 is an incomplete partial enlarged view of FIG. 4; FIG. 8 is a partial three-dimensional exploded view of the embodiment; FIG. 9 is a cross-sectional view similar to FIG. 6, but the first clutch is in a locked position relative to the second clutch; FIG. 10 is a cross-sectional view similar to FIG. 7, but the first clutch is in the locked position; and FIG. 11 is a side view illustrating a steering head of the embodiment rotated 90 degrees relative to a housing unit.

The present invention is described in detail below with reference to the attached figures and embodiments.

Referring to FIG. 1 and FIG. 2, an embodiment of the spindle turning device of the present invention comprises a clutch mechanism 10, a mounting seat 5, a turning head 6, and a driving unit 7. The spindle turning device is suitable for a spindle 8, and the spindle 8 comprises a spindle motor 81 disposed on the turning head 6, and a grinding wheel 82 coupled to the spindle motor 81. In this embodiment, the spindle 8 is a grinding machine. In other variations of this embodiment, the spindle 8 can also be a processing axis for other processing purposes, such as a drill bit or a milling cutter, etc.

Referring to Figures 3 to 5, the clutch mechanism 10 includes a housing unit 1, a piston unit 2, a housing unit 3, and a clutch unit 4.

Referring to Figures 3, 6 and 7, the housing unit 1 includes a housing body 12 defining a housing space 11 around a rotation axis L1, and a boss 13 extending from the housing body 12 toward the rotation axis L1 and around the rotation axis L1. The boss 13 has a first side surface 131 and a second side surface 132 oppositely disposed along an axial direction D parallel to the rotation axis L1. An annular groove 133 around the rotation axis L1 is formed on the second side surface 132.

The piston unit 2 includes a fixed seat 21 disposed in the accommodating space 11, a piston member 22, a first O-ring 23, and a second O-ring 24.

The fixed seat 21 has a seat body 211 and a convex ring 212 surrounding and connected to the seat body 211. The seat body 211 has an outer circumference 213 connected to the convex ring 212, an inner circumference 214 opposite to the outer circumference 213 and defining a through hole 215 around the rotation axis L1, an end surface 216 connected between the outer circumference 213 and the inner circumference 214, and a flow channel 217 extending from the end surface 216 along the axial direction D toward the convex ring 212 and then extending to the outer circumference 213. The flow channel 217 has a liquid inlet 218 formed on the end surface 216, and a liquid outlet 219 formed on the outer circumference 213 of the seat body 211 and located between the end surface 216 and the convex ring 212.

The piston member 22 has a piston body 221 surrounding and abutting against the seat body 211, a surrounding portion 222 connected to the piston body 221 and surrounding the convex ring 212, and a convex portion 223 surrounding and connected to the piston body 221 at four equal angle intervals. The surrounding portion 222 abuts between the convex ring 212 and the convex seat 13, and the piston member 22 can move relative to the fixed seat 21 and the convex seat 13 along the axial direction D.

The seat body 211, the convex ring 212, the piston body 221 and the surrounding portion 222 jointly define a chamber 25 surrounding the outer peripheral surface 213 of the seat body 211 and connected to the flow channel 217. The first O-ring 23 is disposed between the seat body 211 and the piston body 221, and the second O-ring 24 is disposed between the convex ring 212 and the surrounding portion 222 to maintain the sealing between the seat body 211, the convex ring 212, the piston body 221 and the surrounding portion 222.

The housing unit 3 covers the piston unit 2 and includes a base wall 31 abutting against the end surface 216 of the seat body 211 along the axial direction D, a surrounding wall 32 connected to the base wall 31, and an oil seal O-ring 33 disposed between the base wall 31 and the end surface 216 of the seat body 211. The base wall 31 is fixed to the end surface 216 and has an inner peripheral surface 311 defining an opening 312 around the rotation axis L1, an outer peripheral surface 313 opposite to the inner peripheral surface 311, and a liquid injection channel 314 extending from the outer peripheral surface 313 toward the inner peripheral surface 311 and connected to the liquid inlet 218 of the flow channel 217. The opening 312 is connected to the through hole 215. The surrounding wall 32 surrounds the piston body 221 and is fixed to the first side surface 131 of the boss 13. The surrounding wall 32 has a plurality of notches 321 for the protrusions 223 to pass through. The oil seal O-ring 33 surrounds the space between the injection channel 314 and the liquid inlet 218 of the flow channel 217.

The user can inject a working fluid (not shown) into the chamber 25 through the injection channel 314 and the flow channel 217 to push the piston body 221, so that the piston member 22 moves relative to the fixed seat 21 along the axial direction D toward the end surface 216 adjacent to the seat body 211. In this embodiment, the working fluid is hydraulic oil. In other variations of this embodiment, the working fluid can also be other liquid or gaseous media, but is not limited to this.

Referring to Figures 3, 7, and 8, the clutch unit 4 includes a first clutch member 41 disposed in the accommodating space 11, a connecting assembly 42 disposed between the piston member 22 and the first clutch member 41, a second clutch member 43 disposed in the accommodating space 11 and facing the first clutch member 41, a limiting member 44 disposed in the accommodating space 11 and fixed to the housing unit 1, and a reset member 45 disposed between the first clutch member 41 and the housing unit 1.

The first clutch 41 and the second clutch 43 are gear rings around the rotation axis L1. The first clutch 41 is movably disposed in the annular groove 133 along the axial direction D. The second clutch 43 is located on the side of the first clutch 41 opposite to the convex seat 13 and can rotate around the rotation axis L1. The connecting assembly 42 has four fixing members 421 respectively disposed on the convex portions 223. Each fixing member 421 has two shoulder screws 422 that can movably pass through the respective convex portions 223 along the axial direction D and are screwed to the first clutch 41. In other variations of this embodiment, the number of the protrusions 223, the notches 321, and the fixing members 421 may be three or more than five, respectively, but is not limited thereto.

The limiting member 44 has a fixed gear ring 441 fixed to the housing body 12 and surrounding the second clutch member 43, and a plurality of positioning pins 442 passing through the fixed gear ring 441 and the first clutch member 41. The first clutch member 41 faces the fixed gear ring 441 and can move relative to the fixed gear ring 441 along the positioning pins 442. The positioning pins 442 restrict the first clutch member 41 from rotating relative to the fixed gear ring 441.

Referring to FIG. 3 and FIG. 6, the reset member 45 includes a plurality of compression springs 451 disposed at angular intervals on a side of the first clutch member 41 opposite to the second clutch member 43. The compression springs 451 are elastically supported between the first clutch member 41 and the convex seat 13 and have the elasticity to make the first clutch member 41 always move toward the second clutch member 43.

Referring to Figures 3, 7, and 8, the mounting seat 5 includes, in sequence along the axial direction D, a ring seat member 51 abutting against a side of the second clutch member 43 opposite to the first clutch member 41 and surrounding the rotation axis L1, a ring plate 52 abutting against the ring seat member 51 and surrounding the rotation axis L1, an adapter member 53 abutting against the ring plate 52, a plurality of first fixing screws 54 sequentially passing through the ring plate 52 and the ring seat member 51 and locking the second clutch member 43, and a plurality of second fixing screws 55 sequentially passing through the ring seat member 51 and the ring plate 52 and locking the adapter member 53.

Referring to FIG. 4 and FIG. 7, the steering head 6 includes a connecting portion 61 fixed to a side of the adapter 53 opposite to the second clutch 43, and a mounting portion 62 connected to the connecting portion 61. The mounting portion 62 defines a mounting space 621 for the spindle motor 81 around a central axis L2. The rotation axis L1 intersects the central axis L2 at a steering angle θ. The spindle motor 81 can drive the grinding wheel 82 to rotate around the central axis L2. In this embodiment, the steering angle θ is 45 degrees, but the shape of the mounting portion 62 can also be adjusted as needed to change the steering angle θ, and is not limited thereto.

Referring to FIG. 3 and FIG. 6, the drive unit 7 is disposed in the accommodation space 11 and includes a drive motor 71 disposed on a side of the base wall 31 opposite to the fixed seat 21, a transmission member 72 coupled to the drive motor 71 and passing through the through hole 215 and the opening 312, and a reducer 73 fixed to the convex seat 13 and surrounded by the second clutch member 43. The reducer 73 is a planetary gear reducer and is coupled between the transmission member 72 and the adapter 53. The drive motor 71 can drive the transmission member 72 to rotate, and the transmission member 72 drives the reducer 73 when rotating, so that the reducer 73 drives the adapter 53 to rotate.

The operation process of the clutch mechanism 10 of this embodiment is further described as follows.

6 and 7 , when the working fluid is injected into the chamber 25 in the direction of the arrow shown in FIG. 6 to push the piston body 221 away from the convex ring 212, the convex portions 223 of the piston member 22 drive the first clutch member 41 away from the second clutch member 43 along the axial direction D through the convex shoulder screws 422, so that the first clutch member 41 is changed to a separation position relative to the second clutch member 43. When the first clutch 41 is in the separation position, the piston body 221 is away from the convex ring 212 along the axial direction D, the first clutch 41 is away from the second clutch 43 and the fixed gear ring 441, and the first clutch 41 abuts against the convex seat 13 and compresses the compression spring 451, and the second clutch 43 can rotate around the rotation axis L1. Since the adapter 53 is indirectly connected to the second clutch 43, the reducer 73 can drive the adapter 53 to rotate, so that the adapter 53 drives the steering head 6 to rotate.

Referring to Figures 6, 9 and 10, when the first clutch 41 is located at the separation position and the working fluid stops being injected into the chamber 25, the compression springs 451 will push the first clutch 41 against the second clutch 43, and the first clutch 41 drives the piston body 221 of the piston 22 toward the convex ring 212 through the shoulder screws 422, and discharges the working fluid in the chamber 25 through the flow channel 217 and the injection channel 314 in the direction of the arrow shown in Figure 9, so that the first clutch 41 is changed to a locked position relative to the second clutch 43.

When the first clutch 41 is in the locking position, the piston body 221 is adjacent to the convex ring 212 along the axial direction D, and the first clutch 41 abuts against and engages the second clutch 43 and the fixed gear ring 441 along the axial direction D. The fixed gear ring 441 restricts the first clutch 41 from rotating around the rotation axis L1, and the first clutch 41 restricts the second clutch 43 from rotating around the rotation axis L1. Therefore, the adapter 53 cannot rotate relative to the housing unit 1, so that the steering head 6 cannot rotate, thereby fixing the position of the steering head 6.

It can be seen that when the direction of the steering head 6 needs to be changed, the working fluid is injected into the chamber 25 to move the first clutch 41 to the separation position, and the driving motor 71 can be operated to rotate the steering head 6 to a specified position. Then, the injection of the working fluid is stopped, and the first clutch 41 will be resisted by the compression spring 451 to engage the second clutch 43 and the fixed gear ring 441, fixing the position of the steering head 6.

It is worth noting that in other variations of this embodiment, the limiter 44 may also only have the positioning pins 442, and the positioning pins 442 are inserted between the first clutch 41 and the housing body 12. In this case, the limiter 44 can also limit the first clutch 41 from rotating around the rotation axis L1.

The effects and functions that the steering head 6 of this embodiment can achieve at different steering positions are further described below.

Referring to Figure 1, the central axis L2 of the mounting portion 62 extends horizontally, and at this time the spindle turning device combined with the spindle 8 can be used as a horizontal spindle.

Referring to Figure 11, when the steering head 6 rotates 90 degrees relative to the housing unit 1, the central axis L2 of the mounting portion 62 extends up and down, and the spindle steering device combined with the spindle 8 can be used as a vertical spindle. It can be seen that the spindle steering device of the present invention can easily and quickly switch the spindle 8 between the vertical direction and the horizontal direction, so that it can be used as a vertical spindle or a horizontal spindle, and can be applied to linear grinders or rotary grinders. In addition, the spindle 8 can also be changed to other angles, greatly expanding the scope of processing applications.

In summary, the spindle steering device of the present invention has a smaller piston structure formed by the piston member 22 surrounding the fixing seat 21, and the boss screws 422 are used to connect the convex parts 223 of the piston member 22 and the first clutch member 41, so that the drive unit 7, the piston unit 2 and the clutch unit 4 can be compactly combined, reducing the movable space required for the mounting seat 5 to rotate, and greatly reducing the axial and radial dimensions of the spindle steering device. In addition, the spindle steering device has a simple structure and is lightweight as a whole, so as to improve the mobility and precision of the steering head 6, so the purpose of the present invention can be achieved.

However, the above is only an example of the implementation of the present invention, and it cannot be used to limit the scope of the implementation of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still within the scope of the patent of the present invention.

1: Shell unit

11: Storage space

12: Shell body

41: First clutch

43: Second clutch

5: Mounting seat

53: Adapter

6: Turn your head

61:Connection part

62: Installation Department

621: Installation space

L1: Rotation axis

L2: Center axis

θ: Turning angle

Claims (10)

A clutch mechanism of a spindle steering device comprises: a housing unit defining a housing space; a piston unit, comprising a fixed seat disposed in the housing space and connected to the housing unit, and a piston member surrounding the fixed seat and defining a chamber together with the fixed seat, the piston member being pushed by a working fluid injected into the chamber and moving in an axial direction relative to the fixed seat; and A clutch unit includes a first clutch member disposed in the accommodating space, a connecting group disposed between the piston member and the first clutch member, a second clutch member disposed in the accommodating space and facing the first clutch member along the axial direction, a stopper disposed in the accommodating space and fixed to the housing unit, and a reset member disposed between the first clutch member and the housing unit, the reset member having elasticity for making the first clutch member always move toward the second clutch member, the piston member can drive the connecting group to move along the axial direction, so that the connecting group drives the first clutch member away from the second clutch member. The first clutch can be switched between a separation position and a locking position relative to the second clutch. When the first clutch is in the separation position, the first clutch is away from the second clutch, and the second clutch can rotate relative to the housing unit around a rotation axis parallel to the axial direction. When the first clutch is in the locking position, the first clutch is adjacent to the second clutch and coupled to the second clutch and the limiter. The limiter restricts the first clutch from rotating around the rotation axis, and the first clutch restricts the second clutch from rotating around the rotation axis. The clutch mechanism of the spindle steering device as described in claim 1, wherein the fixed seat has a seat body and a convex ring surrounding and connected to the seat body, the piston member has a piston body surrounding and abutting against the seat body, a surrounding portion connected to the piston body and surrounding and abutting against the convex ring, and a plurality of convex portions surrounding and connected to the piston body, the seat body has a flow channel connected to the chamber, and the seat The main body, the convex ring, the piston body and the surrounding part jointly define the chamber. The connecting assembly has a plurality of fixing members, each of which is arranged between the respective convex part and the first clutch member. When the first clutch member is located at the separation position, the piston body is far away from the convex ring along the axis. When the first clutch member is located at the locking position, the piston body is adjacent to the convex ring along the axis. The clutch mechanism of the spindle steering device as described in claim 2, wherein the seat body has an outer peripheral surface connected to the convex ring and adjacent to the chamber, an inner peripheral surface opposite to the outer peripheral surface and surrounding the rotation axis, and an end surface connected between the outer peripheral surface and the inner peripheral surface, the flow channel extends from the end surface along the axial direction toward the convex ring and then extends to the chamber, the flow channel has a liquid inlet formed on the end surface, and a liquid outlet formed on the outer peripheral surface of the seat body, the liquid outlet is located between the end surface and the convex ring The clutch mechanism further comprises a housing unit covering the piston unit, the housing unit comprising a base wall abutting against the end face of the seat body along the axial direction, and a surrounding wall connected to the base wall and surrounding and abutting against the piston body, the base wall having an inner surrounding surface surrounding the rotation axis, an outer surrounding surface opposite to the inner surrounding surface, and an injection channel extending from the outer surrounding surface toward the inner surrounding surface and connected to the flow channel, the surrounding wall having a plurality of notches for the protrusions to pass through respectively. The clutch mechanism of the spindle steering device as described in claim 1, wherein the reset member includes a plurality of compression springs arranged on a side of the first clutch member opposite to the second clutch member and springing between the first clutch member and the housing unit. The clutch mechanism of the spindle steering device as described in claim 1, wherein the first clutch member and the second clutch member are respectively gear rings surrounding the rotation axis, and when the first clutch member is located in the locking position, the first clutch member abuts against and engages the second clutch member along the axial direction. A clutch mechanism for a spindle steering device as described in claim 5, wherein the housing unit includes a housing body defining the accommodating space around the rotation axis, and a boss extending from the housing body toward the rotation axis and surrounding and abutting against the piston member, the boss having a first side surface and a second side surface arranged oppositely along the axis, an annular groove surrounding the rotation axis and accommodating the first clutch member is formed on the second side surface, the second clutch member is located on a side of the annular groove opposite to the first clutch member, and when the first clutch member is located in the separation position, the first clutch member abuts against the boss. The clutch mechanism of the spindle steering device as described in claim 5, wherein the limit member has a fixed gear ring fixed to the housing unit and surrounding the second clutch member, the fixed gear ring faces the first clutch member, when the first clutch member is in the separation position, the first clutch member is away from the second clutch member and the fixed gear ring, when the first clutch member is in the locking position, the first clutch member abuts against and engages with the second clutch member and the fixed gear ring. The clutch mechanism of the spindle steering device as described in claim 7, wherein the limit member also has a plurality of positioning pins passing through the fixed gear ring and the first clutch member, the first clutch member can move relative to the fixed gear ring along the positioning pins, and the positioning pins restrict the first clutch member from rotating relative to the fixed gear ring. A spindle turning device, suitable for a spindle setting, comprises: A clutch mechanism as described in any one of claim 1 to claim 8; A mounting seat, arranged on the side of the second clutch member opposite to the first clutch member; A turning head, arranged on the side of the mounting seat opposite to the second clutch member and used for the spindle setting; and A driving unit, arranged in the accommodating space and used to drive the mounting seat to rotate. A spindle steering device as described in claim 9, wherein the steering head includes a connecting portion arranged on the mounting seat, and a mounting portion connected to the connecting portion, the mounting portion defines an installation space for the spindle to be set around a central axis, and the rotation axis intersects the central axis at a steering angle.