JP7554441B1 - Wheel drive unit - Google Patents

Abstract

[Problem] To provide a wheel drive device that can be configured compactly. [Solution] The wheel drive device 10 includes a motor 30 that rotates a motor shaft 31, a reducer 40 that has an input shaft 41 and an output shaft 42 parallel to the motor shaft 31 and reduces the rotation of the input shaft 41, an axle 52 that is parallel to the motor shaft 31 and rotates with the rotation of the output shaft 42 of the reducer 40, and a frame 20 that holds the motor 30, the reducer 40, and the axle 52. The motor 30, the reducer 40, and the axle 52 are aligned in a first direction perpendicular to the motor shaft 31. This configuration makes it possible to make the wheel drive device compact. [Selected Figure] Figure 3

Description

This invention relates to a wheel drive device for use in moving objects, etc.

Wheel drive devices that combine a motor and a reducer into a single unit are sometimes used in vehicles that run on roads (see, for example, Patent Document 1 below).

JP 2021-014168 A

However, there are various needs for objects such as moving bodies to which wheel drive devices are attached, such as the need to make the object smaller overall and the need to place the wheel drive device in a specific, limited space. In order to meet such diverse needs, various wheel drive devices with innovative layouts for each component are required.

The aim of this invention is to provide a wheel drive device that can be constructed in a compact size.

The wheel drive device of the first invention is a wheel drive device that includes a motor that rotates a motor shaft, a reducer that has an input shaft and an output shaft parallel to the motor shaft and reduces the rotation of the input shaft, an axle that is parallel to the motor shaft and rotates with the rotation of the output shaft of the reducer, and a frame that holds the motor, reducer, and axle so that the motor, reducer, and axle are aligned in a first direction perpendicular to the motor shaft.

This configuration allows the wheel drive device to be made compact.

The wheel drive device of the second invention is a wheel drive device that, compared to the first invention, is equipped with a first transmission structure that transmits rotational force from the motor shaft to the input shaft by an endless flexible member, and a second transmission structure that transmits rotational force from the output shaft to the axle by an endless flexible member.

This configuration allows the use of a reducer with a relatively small load capacity in the direction perpendicular to the output shaft, making it possible to construct a compact wheel drive unit with a large load capacity.

The wheel drive device of the third invention is different from the wheel drive device of the second invention in that the input shaft protrudes from the main body of the reducer in a second direction parallel to the motor shaft, and the output shaft protrudes from the main body of the reducer in a direction opposite to the direction in which the input shaft protrudes in the second direction.

This configuration improves the maintainability of the wheel drive device.

The wheel drive device of the fourth invention is a wheel drive device according to any one of the first to third inventions, which includes a base portion located farther from the motor than the axle in the first direction, and a suspension device configured to support the base portion relative to the frame in the first direction, and the suspension device has a spring located farther from the base portion than the axle in the first direction.

This configuration makes it possible to relatively lower the center of gravity of the object on which the wheel drive device is used, and also cushions vibrations from the road surface so that they are not transmitted directly to the base unit.

The wheel drive device of the fifth invention is a wheel drive device in which, compared to the fourth invention, two or more suspension devices are provided, and an axle is disposed between at least one of the two or more suspension devices and at least one other suspension device when viewed from the first direction.

This configuration allows the base part to be supported in a well-balanced manner relative to the frame.

The wheel drive device of the sixth invention is a wheel drive device that, unlike the fourth or fifth invention, is equipped with a linear guide structure that guides the frame and the base unit to move toward and away from each other in a first direction.

This configuration allows the base part to be firmly supported against the frame.

The wheel drive device of the seventh invention is a wheel drive device according to any one of the fourth to sixth inventions, in which the suspension has a first abutment portion fixed to the base and located away from the base in the first direction, and a second abutment portion provided on the frame and located closer to the base in the first direction than the first abutment portion, and the spring is sandwiched between the first abutment portion and the second abutment portion and is configured to be compressed as the base moves away from the frame in the first direction.

This configuration ensures that the vibration damping effect is achieved while keeping the center of gravity of the object on which the wheel drive device is used relatively low.

The present invention provides a wheel drive device that can be configured to be compact.

FIG. 1 is a perspective view showing a schematic configuration of a moving body having a wheel drive device according to an embodiment of the present invention; FIG. FIG. FIG. FIG. 2 is a left side view of the wheel drive device; FIG.

The following describes an embodiment of the wheel drive device with reference to the drawings. In the following description, the coordinates shown in the drawings are common to all the drawings. The Z direction of the coordinates is perpendicular to the horizontal plane. The X direction is perpendicular to the Z direction and perpendicular to each rotation axis described later. The Y direction is perpendicular to the Z direction and perpendicular to the X direction. That is, the Y direction is perpendicular to each rotation axis described later. The Z direction is sometimes called the "up-down direction" (the positive direction on the Z axis as viewed from the origin is the up direction) or the first direction, the X direction is sometimes called the "front-rear direction" (the positive direction on the X axis as viewed from the origin is the back direction), and the Y direction is sometimes called the "left-right direction" (the positive direction on the Y axis as viewed from the origin is the left direction) or the second direction. In addition, for each rotation axis, the direction along the rotation axis is sometimes called the "axial direction", and the direction perpendicular to the rotation axis is sometimes called the "radial direction". In the following, the shape and positional relationship of each part may be explained by indicating each direction in this way, but these are defined merely for the convenience of explanation and do not limit the direction or posture of the wheel drive device of the present invention when in use. Furthermore, expressions indicating directions and expressions indicating states such as horizontal, vertical, or orthogonal only indicate that they can be roughly understood in that way, and should not necessarily be interpreted strictly as expressed.

(Embodiment)

First, we will explain a moving body 1, which is an example of an object in which the wheel drive device 10 according to this embodiment is used.

Figure 1 is a perspective view showing the schematic configuration of a moving body 1 having a wheel drive device 10 according to one embodiment of the present invention.

In FIG. 1, detailed illustrations of the wheel drive device 10 and other components are omitted.

The moving body 1 is, for example, capable of traveling on a floor and is used for transporting an object to be transported. The moving body 1 transporting an object to be transported may, for example, mean that the moving body 1 itself transports the object to be transported, or the moving body 1 tows a transport cart on which the object to be transported is loaded. The moving body 1 may move by following an object to be followed. The moving body 1 may also be used for other purposes. The moving body 1 may, for example, be a moving body for guidance, guarding, surveillance, entertainment, etc. That is, the moving body 1 may be a transport robot, a guide robot, a guard robot, a surveillance robot, an entertainment robot, etc. The moving body 1 may, for example, move indoors, move outdoors, or both.

As shown in the figure, the moving body 1 includes, for example, a chassis 2, four wheels 5, two steering devices 8, and two wheel drive devices 10. The chassis 2 is, for example, substantially rectangular in plan view. Two steering devices 8 are arranged on the left and right sides of the front of the chassis 2. Two wheel drive devices 10 are arranged on the left and right sides of the rear of the chassis 2. Wheels 5 are attached to the steering devices 8 and the wheel drive devices 10, respectively, and the four wheels 5 are grounded, so that the moving body 1 can run on the ground surface. The wheel drive devices 10 can rotate the two wheels 5 to move the moving body 1 forward and backward. In addition, the steering devices 8 can change the orientation of the two wheels 5 to change the direction of the moving body 1. Note that the moving body 1 may be configured to turn by generating a rotation difference between the driven wheels 5. In addition, the number, arrangement, whether or not the wheels 5 can be steered, whether or not they can be driven, etc. are not limited to the above. Three or more wheels may be driven by the wheel drive devices 10.

The details will be described later, but in this embodiment, the wheel drive device 10 has a suspension device 80 (shown in FIG. 2). The wheel drive device 10 can be said to be divided into a base part 11 on the side attached to the chassis 2 and an unsprung part 12 on the side to which the wheels 5 are attached, with the suspension device 80 as the boundary. The base part 11 is suspended from the unsprung part 12 via the suspension device 80. In other words, the chassis 2 can travel while suspended from the two wheel drive devices 10 at the rear of the mobile body 1. The suspension device 80 does not have to be provided.

As described below, the wheel drive device 10 is configured in a vertically elongated shape with the main components aligned in the up-down direction (first direction). Therefore, in a plan view, the area of the moving body 1 that is occupied by the wheel drive device 10 is relatively small. In other words, in a plan view, a large area of the chassis 2 where the wheel drive device 10 is not arranged can be secured.

Next, the wheel drive device 10 will be described in detail. In the following explanation, the configuration of one of the wheel drive devices 10 provided on the left and right sides of the above-mentioned moving body 1 will be described. The other wheel drive device 10 may have a symmetrical configuration, or the same configuration may be used with the orientation changed.

Figure 2 is a perspective view of the wheel drive device 10. Figure 3 is a front view of the wheel drive device 10. Figure 4 is a right side view of the wheel drive device 10. Figure 5 is a left side view of the wheel drive device 10. Figure 6 is a plan view of the wheel drive device 10.

The wheel drive device 10 has a base portion 11, an unsprung portion 12, and a suspension device 80. The base portion 11 and the unsprung portion 12 are connected via the suspension device 80. The unsprung portion 12 can be said to be a support portion that supports the chassis 2. In this embodiment, a linear guide structure 90 is provided between the base portion 11 and the unsprung portion 12.

In this embodiment, the unsprung portion 12 includes a frame 20, a motor 30, a reduction gear 40, an axle portion 50, a first transmission structure 60, and a second transmission structure 70.

The motor 30 is, for example, an inner rotor type servo motor, but may be another type of motor, for example, a brushless DC motor. The motor 30 is driven, for example, by a drive circuit (not shown), and rotates the motor shaft 31. The motor 30 is used as a power source to rotate the axle 52.

The reducer 40 is provided downstream of the motor 30 and reduces the rotation of the motor 30 before outputting it to the downstream. Any type of reducer 40 can be used. The reduction ratio of the reducer 40 can be set as appropriate. The reducer 40 may be capable of changing the speed by changing the reduction ratio.

The reducer 40 has an input shaft 41 and an output shaft 42. The input shaft 41 and the output shaft 42 are parallel to each other. The input shaft 41 and the output shaft 42 are provided so as to protrude from a reducer body 45 that incorporates a reduction mechanism. In this embodiment, the tip of the input shaft 41 and the tip of the output shaft 42 are located on opposite sides of each other in the axial direction when viewed from the reducer body 45. In other words, the reducer body 45 is located between the tip of the input shaft 41 and the tip of the output shaft 42 in the axial direction. It can be said that the input shaft 41 and the output shaft 42 protrude in different directions from the reducer body 45.

In this embodiment, the input shaft 41 and the output shaft 42 are arranged coaxially. The reducer 40 may be, for example, a planetary reducer.

The axle section 50 is provided at the rear of the reduction gear 40. The axle section 50 has an axle 52 and a bearing section 55 that holds the axle 52. The axle 52 rotates due to the rotational force transmitted from the output shaft 42 of the reduction gear 40 as described below. In other words, the axle 52 rotates in conjunction with the rotation of the output shaft 42 of the reduction gear 40.

Wheels 5 are attached to the axle 52. The wheels 5 usually have tires that come into contact with the ground, but are not limited to this. For example, a sprocket that rotates a caterpillar track may be attached to the axle 52 as the wheels 5.

The frame 20 holds the motor 30, the reducer 40, and the axle 52. In this embodiment, the motor shaft 31, the input shaft 41, the output shaft 42, and the axle 52 are parallel to each other. Each of the rotating shafts 31, 41, 42, and 52 is parallel to the left-right direction (second direction).

In addition, in this embodiment, the frame 20 is configured to hold the motor 30, the reduction gear 40, and the axle 52 so that the motor 30, the reduction gear 40, and the axle 52 are aligned in the vertical direction. Specifically, for example, the motor 30, the reduction gear 40, and the axle 52 are aligned in this order from top to bottom. The reduction gear 40 is located below the motor 30, and the axle 52 is located below the reduction gear 40.

In this embodiment, the tip of the motor shaft 31 and the tip of the input shaft 41 are located on the left side, and the tip of the output shaft 42 and the tip of the axle 52 are located on the right side.

The frame 20 is configured, for example, by combining a lower first frame 21, an upper second frame 22, and a pillar portion 23 that connects the first frame 21 and the second frame 22. Note that the configuration of the frame 20 is not limited to this, and for example, a housing with a monocoque structure may be called a frame.

In this embodiment, the first frame 21 is, for example, a plate-shaped member that is substantially parallel to a horizontal plane. A bearing portion 55 is fixed to the underside of the first frame 21. In other words, the axle 52 is held by the first frame 21.

The second frame 22 is, for example, a plate-shaped member. The second frame 22 is held above the first frame 21 by pillars 23 erected on the first frame 21. A motor 30 is fixed to the upper part of the second frame 22. A reducer 40 is fixed to the lower surface of the second frame 22.

The frame 20 has such a two-layer structure, and the motor 30, the reduction gear 40, and the axle 52 are arranged side-by-side and spaced apart from each other in the vertical direction.

The first transmission structure 60 transmits rotational force from the motor shaft 31 to the input shaft 41. In this embodiment, the first transmission structure 60 has a first sprocket 61, a second sprocket 62, and an endless flexible member 65.

In this embodiment, the first transmission structure 60 is configured using a chain as the endless flexible member 65. That is, the first sprocket 61 is fixed to the motor shaft 31. The second sprocket 62 is fixed to the input shaft 41. The endless flexible member 65 is hung on the first sprocket 61 and the second sprocket 62. This allows the rotational force of the motor 30 to be transmitted to the input shaft 41. The first transmission structure 60 is disposed on the left side.

The first transmission structure 60 has a first idler 63. The first idler 63 is arranged to maintain tension on the endless flexible member 65. The first idler 63 may be a tensioner biased by a spring or the like, or may be fixed in an adjusted position under normal circumstances. The first idler 63 does not necessarily have to be provided.

The second transmission structure 70 transmits rotational force from the output shaft 42 to the axle 52. In this embodiment, the second transmission structure 70 has a third sprocket 71, a fourth sprocket 72, and an endless flexible member 75.

In this embodiment, the second transmission structure 70 is configured using a chain as the endless flexible member 75. That is, the third sprocket 71 is fixed to the output shaft 42. The fourth sprocket 72 is fixed to the axle 52. The endless flexible member 75 is hung on the third sprocket 71 and the fourth sprocket 72. This allows the rotational force of the output shaft 42 to be transmitted to the axle 52. The second transmission structure 70 is disposed on the right side.

The second transmission structure 70 has a second idler 73. The second idler 73 is arranged to maintain tension on the endless flexible member 75. The second idler 73 may be a tensioner biased by a spring or the like, or may be fixed in an adjusted position under normal circumstances. The second idler 73 does not necessarily have to be provided.

The transmission structure 60, 70 is not limited to including sprockets 61, 62, 71, 72 fixed to a rotating shaft and endless flexible members 65, 75 which are chains. For example, a belt made of rubber or synthetic resin may be used as the endless flexible members 65, 75. In this case, a pulley around which the belt is fastened may be attached to each rotating shaft.

The base 11 is disposed below the unsprung part 12, which includes the various parts held by the frame 20 as described above. The base 11 is, for example, a plate-shaped member, and is disposed approximately parallel to the horizontal plane. The base 11 is disposed below the axle 52. That is, the base 11 is located farther from the motor 30 than the axle 52 in the vertical direction. Note that the shape and configuration of the base 11 are not limited to this. For example, a base 11 may be used in which a portion of the unsprung part 12, such as the axle 52, is chipped or recessed due to a change in the relative position between the unsprung part 12 and the base 11.

The suspension device 80 is arranged so that at least a portion of it is located between the base portion 11 and the unsprung portion 12 in the vertical direction. The suspension device 80 is configured to support the base portion 11 relative to the frame 20 in the vertical direction. In this embodiment, the suspension device 80 holds the base portion 11 in a suspended state relative to the frame 20 so that the base portion 11 does not move too far away from the frame 20 in the vertical direction.

Two suspension devices 80 are provided. When viewed from above, the axle 52 is disposed between the two suspension devices 80. It can also be said that the axle 52 is disposed between the two springs 81. This allows the load from the base part 11 to be supported in a well-balanced manner with respect to the axle 52 to which the grounded wheel 5 is attached. Note that three or more suspension devices 80 may be provided, in which case it is sufficient that the axle 52 is disposed between at least one suspension device 80 and the other suspension devices 80. Note that only one suspension device 80 may be provided.

In this embodiment, the suspension device 80 is configured using a spring 81, which is, for example, a compression coil spring. That is, the suspension device 80 includes the spring 81, a first contact portion 82, and a second contact portion 86.

The first abutment portion 82 is fixed to the base portion 11. The first abutment portion 82 is located above the base portion 11. In this embodiment, the first abutment portion 82 is located above the first frame 21. The first abutment portion 82 is located above the axle 52. The first abutment portion 82 has, for example, a rod 85 extending upward from the base portion 11, and is configured so as to be able to contact the upper end of the spring 81 by a dish-shaped member fixed to the rod 85.

The second abutment portion 86 is provided on the frame 20. The second abutment portion 86 is located closer to the base portion 11 than the first abutment portion 82 in the vertical direction, i.e., lower than the first abutment portion 82. In this embodiment, the second abutment portion 86 is part of the upper surface of the first frame 21, but is not limited to this. For example, the second abutment portion 86 may be formed by fixing a dish-shaped member to the first frame 21. The second abutment portion 86 is capable of contacting the lower end of the spring 81.

The spring 81 is sandwiched between the first contact portion 82 and the second contact portion 86 in the vertical direction. The spring 81 is located farther from the base portion 11 than the axle 52 in the vertical direction, i.e., above the axle 52. The spring 81 is located above the first frame 21.

The suspension device 80 configured in this manner is configured so that the spring 81 is compressed as the base portion 11 moves away from the frame 20 in the vertical direction. That is, as the base portion 11 is displaced downward relative to the unsprung portion 12 that is in contact with the ground surface, the spring 81 is compressed, and the repulsive force of the spring 81 increases. Therefore, the base portion 11 is held so that it does not displace too far downward relative to the unsprung portion 12. Because the base portion 11 is held in this manner via the suspension device 80, it is possible to prevent vibrations applied to the unsprung portion 12 from being directly transmitted to the base portion 11.

In this embodiment, the suspension device 80 has a damper (shock absorbing device) 84. The damper 84 is fixed to the first frame 21, for example, with a rod 85 passing through it. A piston is provided in the rod 85, and the rod 85 is configured to absorb shock and dampen vibrations by the resistance force generated when the piston moves inside the damper 84. In other words, the damper 84 and the rod 85 form a through-rod type shock absorbing device. By using a wheel drive device 10 that uses such a damper 84, it is possible to dampen vibrations and drive smoothly. The damper 84 does not necessarily have to be provided.

The suspension device 80 may also use other types of springs as the springs 81. For example, a structure that uses disc springs to support the load may be used.

The linear guide structure 90 guides the frame 20 and the base 11 so that they move toward and away from each other in the vertical direction. The linear guide structure 90 includes, for example, a shaft 91 fixed to the base 11 and a linear bearing 92 fixed to the frame 20. In this embodiment, the linear bearing 92 is, for example, a linear bushing or an oil-free bushing, and is fixed to the first frame 21. The shaft 91 is arranged so that its longitudinal direction is the vertical direction. The linear bearing 92 can move along the shaft 91 while holding the shaft 91. By providing, for example, two sets of such linear guide structures 90, the base 11 can be displaced only in the vertical direction relative to the frame 20.

By using such a linear guide structure 90 together with the suspension device 80, a wheel drive device 10 can be constructed that reliably suppresses the transmission of vertical shocks.

The shaft 91 may be attached to the frame 20, and the linear bearing 92 may be attached to the base 11. The linear guide structure 90 may be a structure using a linear guide having rails arranged along the vertical direction. The linear guide structure 90 may not necessarily be used.

As described above, in this embodiment, the motor 30, the reduction gear 40, and the axle 52 are arranged in the vertical direction, so that the wheel drive device 10 is configured to be vertically long as a whole. The area occupied by the wheel drive device 10 when viewed from above can be made relatively small.

The required reduction ratio can be obtained by using a small reducer 40 with small radial dimensions centered on the input shaft 41 and output shaft 42, without using bevel gears or the like that require a relatively large space. Therefore, the wheel drive device 10 can be configured to be relatively small.

The transmission structures 60, 70 are constructed using endless flexible members 65, 75, so maintenance work can be easily performed. Even if an impact is applied to the axle 52 during driving, the impact is unlikely to be transmitted to the upper reduction gear 40 or motor 30, so the durability of the wheel drive device 10 can be improved.

The input shaft 41 protrudes to the left from the reducer body 45, and the output shaft 42 protrudes to the right from the reducer body 45, i.e., in the opposite direction to the direction in which the input shaft 41 protrudes in the left-right direction. Since the first transmission structure 60 is disposed on the left side and the second transmission structure 70 is disposed on the right side, the height of the wheel drive device 10 can be kept low. In addition, since the first transmission structure 60 and the second transmission structure 70 can be independently modified, the workability during maintenance work can be improved.

(others)
The present invention is not limited to the above-described embodiment, and various modifications are possible, which are also included within the scope of the present invention.

Some of the components of the above-mentioned embodiments may be omitted. For example, the wheel drive device may not have a suspension device and a base part. Also, a part of the object to which the wheel drive device is attached may be understood as the base part, in which case it is preferable that the object is supported by the frame side via the suspension device.

As described above, the wheel drive device of the present invention has the advantage of being compact and is useful as a wheel drive device, etc.

REFERENCE SIGNS LIST 1 Mobile body 5 Wheel 10 Wheel drive device 11 Base 20 Frame 30 Motor 31 Motor shaft 40 Reducer 41 Input shaft 42 Output shaft 45 Reducer body 52 Axle 60 First transmission structure 65, 75 Endless flexible member 70 Second transmission structure 80 Suspension device 81 Spring 82 First contact portion 86 Second contact portion 90 Linear guide structure 91 Shaft 92 Linear bearing

Claims (5)

A motor that rotates a motor shaft;
a reducer having an input shaft and an output shaft parallel to the motor shaft, the reducer reducing the rotation speed of the input shaft;
an axle that is parallel to the motor shaft and rotates in accordance with the rotation of the output shaft of the reducer;
a frame that holds the motor, the reducer, and the axle such that the motor, the reducer, and the axle are aligned in a first direction perpendicular to the motor shaft ;
a first transmission structure that transmits a rotational force from the motor shaft to the input shaft by an endless flexible member;
a second transmission structure that transmits a rotational force from the output shaft to the axle by an endless flexible member ,
The input shaft protrudes from a main body of the reducer in a second direction parallel to the motor shaft,
A wheel drive device, wherein the output shaft protrudes from a main body of the reducer in a second direction opposite to a direction in which the input shaft protrudes . A motor that rotates a motor shaft;
a reducer having an input shaft and an output shaft parallel to the motor shaft, the reducer reducing the rotation speed of the input shaft;
an axle that is parallel to the motor shaft and rotates in accordance with the rotation of the output shaft of the reducer;
a frame that holds the motor, the reducer, and the axle such that the motor, the reducer, and the axle are aligned in a first direction perpendicular to the motor shaft;
a base portion located farther from the motor than the axle in a first direction;
a suspension configured to support the base relative to the frame in a first direction;
A wheel drive device, wherein the suspension device has a spring arranged at a position farther from the base portion than the axle in a first direction. Two or more suspension devices are provided,
The wheel drive device according to claim 2 , wherein the axle is disposed between at least one of the two or more suspension devices and at least one other of the two or more suspension devices when viewed from a first direction. The wheel drive device according to claim 2 , further comprising a linear motion guide structure that guides the frame and the base portion so as to move toward and away from each other in a first direction. The suspension device comprises:
A first contact portion fixed to the base portion and located away from the base portion in a first direction;
a second contact portion provided on the frame and located closer to the base portion than the first contact portion in a first direction;
3. The wheel drive device according to claim 2, wherein the spring is sandwiched between the first abutment portion and the second abutment portion and is configured to be compressed as the base portion moves away from the frame in a first direction.

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