JP7145248B2 - Wheel drives and series of wheel drives - Google Patents

Description

The present invention relates to a wheel drive and a series of wheel drives.

2. Description of the Related Art Conventionally, as a wheel driving device for driving a wheel of a carriage or the like, one having a speed reduction mechanism incorporated therein is known. For example, Patent Literature 1 discloses a wheel drive device that includes a rotating body to which rotation is transmitted from a speed reduction mechanism, and a tire fitted on the outer peripheral side of the rotating body.

JP 2012-71810 A

The wheel drive device of Patent Document 1 employs a structure in which a stepped fitting surface parallel to the axial direction is provided on the outer peripheral surface of the rotating body, and a tire wheel is fitted to the outside of the fitting surface. As a result of investigation, the inventors of the present invention have found that in this structure, fretting wear is likely to occur between the fitting surface of the rotating body and the wheel. Since fretting wear causes trouble, countermeasures against it are desired.

SUMMARY OF THE INVENTION An aspect of the present invention has been made in view of such circumstances, and one of the objects thereof is to provide a wheel driving device capable of taking countermeasures against fretting wear.

One aspect of the present invention relates to a wheel drive device, comprising: a reduction mechanism that reduces rotation transmitted from a drive source; a cylindrical output member that transmits the rotation reduced by the reduction mechanism; and a tire attached to the baseband, wherein an outer peripheral surface of the output member and an inner peripheral surface of the baseband are provided with tapered surfaces, and the baseband is externally fitted to the output member by an interference fit with the tapered surfaces thereof in contact with the output member.

According to the present invention, it is possible to provide a wheel drive device that can take measures against fretting wear.

It is a front sectional view showing a wheel drive device of this embodiment. 2 is an enlarged view of a portion of FIG. 1; FIG. It is front sectional drawing of the 2nd wheel drive device of this embodiment. FIG. 4(a) is an enlarged view of part of the first wheel drive device, and FIG. 4(b) is an enlarged view of part of the second wheel drive device.

Hereinafter, in the embodiments and modified examples, the same constituent elements are denoted by the same reference numerals, and overlapping descriptions are omitted. Moreover, in each drawing, for convenience of explanation, some of the constituent elements are appropriately omitted, and the dimensions of the constituent elements are shown by appropriately enlarging or reducing them.

First, the background that led to the idea of the wheel drive device of this embodiment will be described. The wheel drive device of the present embodiment includes a cylindrical output member to which rotation of the speed reduction mechanism is transmitted, a base band fitted around the output member, and a tire attached to the base band. In this type of wheel drive device, if fitting wear occurs on the contact surface between the output member and the base band, wear debris will contaminate the surrounding environment. This poses a problem when the wheel drive device is used in an environment such as a clean room where cleanliness is required.

In addition, in this type of wheel drive device, the tires wear out over time, so the baseband may be removed from the output member for the purpose of replacing the tires. In this case, if fitting wear occurs on the contact surface between the output member and the baseband, the output member and the baseband will adhere to each other due to wear debris, making it impossible to remove the baseband from the output member.

Fitting wear between the output member and the baseband is thus a source of failure. As a countermeasure against this, in the wheel drive device of the present embodiment, the base band is externally fitted to the output member by an interference fit. As a result, even when the baseband and the output member are slightly vibrated, the contact surfaces of the two can be maintained in close contact with each other. Therefore, it is possible to suppress the relative displacement of the contact surface due to this slight vibration, and prevent the occurrence of fretting wear due to the relative displacement.

Further, in the wheel drive device of this embodiment, the tapered surfaces are provided on the base band and the output member, and the base band is fitted onto the output member while the tapered surfaces are in contact with each other. As a result, it is possible to realize an interference fit with a sufficient interference while improving the ease of assembly of the baseband to the output member, and effectively take measures against fretting wear. The details of this wheel driving device will be described below.

FIG. 1 is a front sectional view showing a wheel drive device 10 of this embodiment. The wheel drive device 10 of the present embodiment is assembled to the vehicle body 12 of the carriage and used to drive the tires 28 of the carriage. The carriage of this embodiment is a track-guided carriage, and the tires 28 of this embodiment run on the running surfaces 16a of the rails 16 laid on the floor. Hereinafter, the direction along the rotation center line La of the tire 28 is defined as the axial direction X of the wheel drive device 10 . Also, the circumferential direction and radial direction of a circle centered on the rotation center line La are simply referred to as "circumferential direction" and "radial direction".

The wheel drive device 10 mainly includes a speed reduction mechanism 18 , carriers 20 and 22 , an output member 24 , a baseband 26 and tires 28 .

The deceleration mechanism 18 can decelerate the rotation transmitted from the drive source. Although the drive source in this embodiment is a motor, it is not limited to this, and may be a gear motor, an engine, or the like in which a motor and a reduction gear are integrated. The speed reduction mechanism 18 of this embodiment is an eccentric swing speed reduction mechanism. The reduction mechanism 18 mainly has an input shaft 30 , an eccentric body 32 , an external gear 34 , an eccentric body bearing 36 and an internal gear 38 .

The input shaft 30 is connected to an output shaft 40 of a drive source that protrudes outward in the vehicle width direction from the vehicle body 12, and the rotation output from the output shaft 40 is input.

The eccentric body 32 is provided rotatably integrally with the input shaft 30 . A plurality of eccentric bodies 32 are provided at intervals in the axial direction X. As shown in FIG.

The external gear 34 is individually provided corresponding to each of the plurality of eccentric bodies 32 . The external gear 34 is supported by the corresponding eccentrics 32 via eccentric bearings 36 . The external gear 34 is oscillated by the corresponding eccentric body 32 so that its own axis rotates around the rotation center line La.

The external gear 34 internally meshes with the internal gear 38 . The internal gear 38 of this embodiment has a plurality of outer pins 38a supported by the inner peripheral portion of the output member 24, and a plurality of outer rollers 38b rotatably supported by each of the plurality of outer pins 38a. . Each of the plurality of outer rollers 38b constitutes an internal tooth of the internal gear 38. As shown in FIG. The number of internal teeth (the number of outer rollers 38b) of the internal gear 38 is one more than the number of external teeth of the external gear 34 in this embodiment.

The carriers 20 and 22 include an inner carrier 20 arranged closer to the vehicle body than the external gear 34 and an outer carrier 22 arranged further away from the vehicle body than the external gear 34 . In this specification, the vehicle body side refers to the vehicle body 12 side in the axial direction X, and the anti-vehicle side refers to the opposite side in the axial direction X from the vehicle body 12 .

A through hole 42 is formed in the carriers 20 and 22 so as to extend through the radial central portion thereof. An input shaft bearing 44 is arranged inside the through hole 42 , and the carriers 20 and 22 rotatably support the input shaft 30 via the input shaft bearing 44 . The input shaft bearing 44 of this embodiment is a rolling bearing such as a ball bearing.

The output member 24 has a tubular shape as a whole and is made of metal such as steel. A speed reduction mechanism 18 and carriers 20 and 22 are arranged on the inner peripheral side of the output member 24 . The rotation reduced by the reduction mechanism 18 is transmitted to the output member 24 . The output member 24 of this embodiment also serves as a casing for the speed reduction mechanism 18, and the internal gear 38 of the speed reduction mechanism 18 is provided on the inner peripheral portion thereof.

A main bearing 46 is positioned between the output member 24 and the carriers 20,22. The main bearing 46 of this embodiment is a rolling bearing such as a roller bearing. The carriers 20 , 22 are connected to the vehicle body 12 through wheel covers 56 to be described later, and function as support members that rotatably support the output member 24 through the main bearings 46 .

FIG. 2 is an enlarged view of part of FIG. The baseband 26 is arranged on the outer peripheral side of the output member 24 and fitted onto the output member 24 . The base band 26 has a tubular shape as a whole and is made of metal such as steel. Open ends 48 are formed on both sides in the axial direction X on the inner peripheral portion of the base band 26 . The output member 24 is provided so as to be accommodated inside in the axial direction X from the open end 48 of the base band 26 . The baseband 26 is integrated with the output member 24 by being fitted over the output member 24 by an interference fit, as described below.

The tire 28 is attached to the outer peripheral portion of the base band 26 by adhesion or the like. The tire 28 is constructed using a soft material that is softer than the base band 26 . As an example, the tire 28 is constructed using an elastic body such as urethane rubber.

The operation of the speed reduction mechanism 18 will be described.
When the rotation of the drive source is transmitted from the output shaft 40 to the input shaft 30, the input shaft 30 rotates. When the input shaft 30 rotates, the rotation of the input shaft 30 is decelerated by the deceleration mechanism 18 and transmitted to the output member 24 . When rotation is transmitted to the output member 24 from the deceleration mechanism 18, the tire 28 rotates together with the base band 26 integrated with the output member 24, so that the tire 28 runs on the running surface 16a.

In the speed reduction mechanism 18 of the present embodiment, when the input shaft 30 rotates, the eccentric body 32 rotates around the rotation center line La together with the input shaft 30 . When the eccentric body 32 rotates around its rotation center line La, the external gear 34 oscillates so that the axis of the external gear 34 rotates around its rotation center line La. When the external gear 34 oscillates, the meshing positions of the external gear 34 and the internal gear 38 are sequentially displaced. As a result, each time the input shaft 30 makes one rotation, the internal gear 38 rotates (rotates) relative to the external gear 34 by an amount corresponding to the difference in the number of teeth from the external gear 34, and its rotation component is transmitted to the output member 24 . At this time, the rotation of the input shaft 30 is reduced at a speed reduction ratio corresponding to the difference in the number of teeth between the external gear 34 and the internal gear 38 and transmitted from the internal gear 38 to the output member 24 .

Here, an outer peripheral tapered surface 50 is provided on the outer peripheral surface of the output member 24 of this embodiment. The inner peripheral surface of the base band 26 is provided with an inner peripheral tapered surface 52 that radially faces the outer peripheral tapered surface 50 of the output member 24 . The outer tapered surface 50 and the inner tapered surface 52 are formed so that the outer diameter or the inner diameter decreases from one side in the axial direction X toward the other side. The outer tapered surface 50 and the inner tapered surface 52 of this embodiment are formed so as to decrease in diameter from the vehicle body side (right side in FIG. 2) in the axial direction X toward the anti-vehicle side (left side in FIG. 2). be. Hereinafter, the direction in which the tapered surfaces 50 and 52 decrease in diameter in the axial direction X will be referred to as a diameter decreasing direction Pa, and the direction in which the tapered surfaces 50 and 52 will increase in diameter will be referred to as a diameter increasing direction Pb.

The outer peripheral tapered surface 50 and the inner peripheral tapered surface 52 are linear tapers in which the diameter changes linearly (linearly) with respect to the change in the distance in the axial direction X. The taper ratios of the outer peripheral tapered surface 50 and the inner peripheral tapered surface 52 are set to be the same. The taper rate here means the rate of change in diameter with respect to change in distance in the axial direction X. As shown in FIG. In addition, the inner peripheral tapered surface 52 is set to have a larger axial dimension than the outer peripheral tapered surface 50 . The axial dimension here means the dimension along the axial direction X. As shown in FIG. The term "same" as used in this specification includes not only completely the same but also substantially the same.

The baseband 26 is fitted onto the output member 24 by an interference fit with the tapered surfaces 50 and 52 of the output member 24 in contact with each other. This means that the output member 24 and the base band 26 have an interference in the radial direction and the base band 26 is fitted onto the output member 24 . It can also be understood that the base band 26 is fitted onto the output member 24 while the output member 24 and the base band 26 are elastically deformed in the radial direction. By fitting using this interference fit, the baseband 26 is integrated with the output member 24 with the tapered surfaces 50 and 52 of the output member 24 in close contact with each other.

The base band 26 is provided so as to be positioned outside in the axial direction X from the end surface portions 24 a on both axial sides of the output member 24 . That is, the output member 24 is covered with the base band 26 from the radial outside over the entire length in the axial direction X. As shown in FIG. The base band 26 has a flange portion 26a extending radially inwardly from one end portion (the end portion with the smaller inner diameter) on the side of the diameter reduction direction Pa. The flange portion 26a of the base band 26 is arranged at a position overlapping the end face portion 24a of the output member 24 on the side of the radially decreasing direction Pa when viewed from the axial direction X. As shown in FIG.

The flange portion 26a of the base band 26 and the end surface portion 24a of the output member 24 on the side of the radially decreasing direction Pa are fastened with bolts B1. The shaft portion of the bolt B1 is inserted through an insertion hole 26b formed in the flange portion 26a and screwed into a female screw hole 24b formed in the end surface portion 24a of the output member 24. As shown in FIG. A gap 54 is formed between the flange portion 26 a of the base band 26 and the end face portion 24 a of the output member 24 .

In the wheel drive device 10 described above, the base band 26 is fitted onto the output member 24 by an interference fit, as described above. Therefore, it is possible to suppress the relative displacement between the inner peripheral tapered surface 52 and the outer peripheral tapered surface 50 due to minute vibrations, and prevent the occurrence of fretting wear due to the relative displacement.

In the structure of Patent Document 1, the contact surface between the rotating body and the wheel is parallel to the axial direction. Therefore, if the wheel is fitted onto the rotating body by interference fitting, the wheel must be assembled to the rotating body under the condition that the inner diameter of the wheel is smaller than the outer diameter of the rotating body. . Moreover, under the structure of Patent Document 1, the interference between the rotating body and the wheel cannot be adjusted after the fact. As a result of these factors, it is difficult to secure the necessary interference required to prevent fretting wear while obtaining good assembling performance.

On the other hand, the base band 26 of the present embodiment is fitted onto the output member 24 while the tapered surfaces 50 and 52 of the output member 24 are in contact with each other. Therefore, in a state in which the outer peripheral tapered surface 50 of the output member 24 is arranged on the inner peripheral side of the inner peripheral tapered surface 52 of the base band 26, by applying a tightening force in the axial direction X to the base band 26 and the output member 24, , the state in which the base band 26 and the output member 24 are tightly fitted can be easily realized. Therefore, the assembling property of the baseband to the output member 24 is good. Here, the tightening force in the axial direction X refers to the force applied in the direction in which the output member 24 and the base band 26 are brought closer to each other in the axial direction X. As shown in FIG.

Further, by adjusting the magnitude of the tightening force applied to the baseband 26 and the output member 24 in the axial direction X, the radial tightening margin of the baseband 26 and the output member 24 can be adjusted. Therefore, by adjusting the tightening force applied to the base band 26 and the output member 24, it is possible to easily secure the necessary tightening margin required to prevent fretting wear. In combination with these, according to the wheel drive device 10 of the present embodiment, it is possible to effectively take measures against fretting wear.

Further, the flange portion 26a of the base band 26 and the end surface portion 24a of the output member 24 are fastened with bolts B1. Therefore, the tightening force in the axial direction X between the base band 26 and the output member 24 can be managed through a simple method such as managing the tightening torque of the bolt B1, and the necessary tightening margin required to prevent fretting wear can be easily achieved. can be secured. Note that the tightening torque of the bolt B1 can be managed using a torque wrench or the like.

A gap 54 is formed between the flange portion 26 a of the base band 26 and the end face portion 24 a of the output member 24 . The axial dimension of this gap 54 decreases as the interference between the baseband 26 and the output member 24 increases. Therefore, the interference between the base band 26 and the output member 24 can be easily grasped through visual control of the axial dimension of the gap 54 .

Here, the tightening force in the axial direction X applied to the output member 24 and the base band 26 (hereinafter also simply referred to as "tightening force") may be set so as to satisfy the following conditions. It can also be said that the radial interference between the output member 24 and the base band 26 or the tightening torque of the bolt B1 is set so as to satisfy the following conditions. A load applied to the baseband 26 and necessary for the baseband 26 to start rotating is called a starting load [kgf] of the baseband 26 .

At this time, it is preferable that the tightening force of the base band 26 and the like is set so that the starting load of the base band 26 is 4 kgf or more and 10 kgf or less under the condition that the power transmission path of the speed reduction mechanism 18 and the drive source is disconnected. . These numerical conditions are set based on the results of experimental studies by the inventors. The reason why the power transmission path between the speed reduction mechanism 18 and the drive source is separated is to exclude the rotational resistance of the drive source when considering the starting load of the baseband 26 . This disconnection of the power transmission path is achieved by removing the input shaft 30 of the speed reduction mechanism 18 from the output shaft 40 of the drive source. In the present embodiment, by managing the tightening torque of the bolt B1, the tightening force is set to satisfy the starting load range described above.

If the starting load of the base band 26 is less than 4 kgf, the tightening force of the base band 26 and the like is insufficient, and the tightening margin of the output member 24 is insufficient. As a result, sufficient preload is not applied to both of the pair of bearings spaced apart in the axial direction X on the inner peripheral side of the output member 24, and there is concern that the life of these bearings will be shortened. In this embodiment, the term "pair of bearings" refers to, for example, the main bearing 46 on the vehicle body side and the main bearing 46 on the side opposite to the vehicle body.

If the starting load of the base band 26 exceeds 10 kgf, the tightening force of the base band 26 and the like becomes excessive, and the tightening margin of the output member 24 becomes excessive. As a result, the backlash of the speed reduction mechanism 18 may become excessively small, or the preload of the bearing arranged on the inner peripheral side of the output member 24 may become excessive, thereby excessively increasing the rotational resistance of the rotating body. The rotating bodies here are the external gear 34, the internal gear 38, the main bearing 46, and the like. If the rotation resistance of the rotating body becomes excessively large, there is concern that a large change in the characteristics of the speed reduction mechanism 18 under conditions where no load is applied (hereinafter referred to as no-load characteristics) may adversely affect the speed.

When the starting load of the baseband 26 satisfies the above conditions, the interference fit between the baseband 26 and the output member 24 can be achieved while preventing the no-load characteristics of the speed reduction mechanism 18 and the bearings from being adversely affected.

A method of measuring the starting load of the baseband 26 will be described. First, a push-pull gauge is attached to the end surface of the base band 26 in the axial direction X on the side where the flange 48 is located. Next, the end face portion 24a of the base band 26 is pulled through the push-pull gauge in the tangential direction of the circle centered on the rotation axis La of the tire 28. As shown in FIG. At this time, the tire 28 is kept away from the running surface 16a so that no load is applied to the tire 28. - 特許庁When the baseband 26 starts rotating, the maximum tensile load measured by the push-pull gauge from when the push-pull gauge starts to be pulled until the baseband 26 starts rotating is taken as the starting load of the baseband 26 .

The wheel drive device 10 of this embodiment includes a locking mechanism 55 for controlling loosening of the bolt B1. The locking mechanism 55 of this embodiment is a locking washer interposed between the head of the bolt B1 and the flange portion 26a of the base band 26. As shown in FIG. As a result, the tightening force of the bolt B1 can be prevented from changing over time, and the starting load of the base band 26 can be ensured over a long period of time. The locking mechanism 55 may also be a locking bolt or the like.

Next, other features of the wheel drive system 10 will be described.
Please refer to FIG. The wheel drive device 10 includes a wheel cover 56 that covers the base band 26 and the tire 28 . The wheel cover 56 is formed with an opening 56a through which the base band 26 and the tire 28 protrude downward. The wheel cover 56 has an inner cover member 58 assembled to the vehicle body 12 with bolts (not shown) and an outer cover member 60 detachably attached to the inner cover member 58 with bolts (not shown).

The inner cover member 58 has an inner side cover portion 58a that covers the base band 26 and the tire 28 from the diameter expansion direction Pb of the axial direction X. As shown in FIG. The inner carrier 20 is fixed to the inner side cover portion 58a by carrier bolts B3. The inner cover member 58 of the present embodiment also has an outer peripheral cover portion 58b that covers the tire 28 and the base band 26 from the outer peripheral side.

The outer cover member 60 has an outer side cover portion 60a that covers the tire 28 and the base band 26 in the radial direction Pa of the axial direction X. As shown in FIG. The outer carrier 22 is fixed to the outer side cover portion 60a by fitting.

When the outer cover member 60 is detached from the inner cover member 58 , a portion of the wheel cover 56 does not exist in the diameter reduction direction Pa of the axial direction X with respect to the tire 28 and the base band 26 . Therefore, in this state, the tire 28 and the base band 26 can be replaced by using the space in the radially contracting direction Pa with respect to the tire 28 and the base band 26 as a working space.

Note that the outer cover member 60 can be removed from the inner cover member 58 while the wheel drive device 10 is assembled to the vehicle body 12 . Further, when the outer cover member 60 is removed from the inner cover member 58, the bolts B1 can be attached/detached to/from the output member 24 and the base band 26 while the wheel drive device 10 is assembled to the vehicle body 12. Further, when the bolt B1 is removed from the output member 24 and the base band 26, the base band 26 can be detached from the output member 24 while the wheel drive device 10 is assembled to the vehicle body 12. FIG.

A housing space 62 for housing the speed reduction mechanism 18 is formed on the inner peripheral side of the output member 24 . The storage space 62 is sealed using a plurality of sealing members 64a-64d. Lubricant (not shown) is enclosed in the housing space 62 sealed by the sealing members 64a to 64d.

The sealing members 64a to 64d include an outer peripheral oil seal 64a interposed between the output member 24 and the carriers 20, 22, a seal cap 64b for closing the through hole 42 of the outer carrier 22, and an inner carrier 20 passing through. A shaft cover 64c that closes the hole 42 and an inner peripheral oil seal 64d are included. The outer peripheral oil seal 64a is arranged between the output member 24 and the carriers 20, 22, closer to the outer space than the main bearing 46 is. The shaft cover 64c is arranged closer to the vehicle body than the input shaft bearing 44, and the input shaft 30 penetrates in the axial direction X. As shown in FIG. The inner peripheral oil seal 64 d is interposed between the shaft cover 64 c and the input shaft 30 .

Thus, the sealing members 64a to 64d are arranged between the output member 24 and the carriers 20, 22, on the inner peripheral side of the through holes 42 of the carriers 20, 22, and between the carriers 20, 22 and the wheel cover 56. is not placed. Therefore, when the outer cover member 60 of the wheel cover 56 is removed from the inner cover member 58, the storage space 62 on the inner peripheral side of the output member 24 can be kept sealed by the sealing members 64a to 64d. As a result, the tire 28 can be replaced without disassembling the speed reduction mechanism 18 or adding and removing the lubricant.

Next, the series of wheel drive devices 10 will be described. The invention of the series (product group) of the wheel drive device 10 described below is regarded as the invention of the manufacturing method of the series of the wheel drive device 10 and the invention of the design method (construction method) of the series of the wheel drive device 10. can also

The outer diameter of the tire 28 of the wheel drive device 10 can be of various sizes depending on the requirements of the delivery destination of the wheel drive device 10 and the like. From the viewpoint of reducing management labor, it is desirable to share management items as much as possible among a plurality of wheel drive devices 10 having tires 28 with different outer diameters. The series of the wheel drive device 10 of this embodiment is made under such a background.

The series of wheel drives comprises a first wheel drive 10-A and a second wheel drive 10-B. The first wheel drive device 10-A is the wheel drive device described with reference to FIGS. 1 and 2. FIG. FIG. 3 is a front sectional view of the second wheel drive device 10-B. The second wheel drive 10-B comprises many of the same components as the first wheel drive 10-A. In the following description, the same names are used for the same components in the first wheel drive device 10-A and the second wheel drive device 10-B. When distinguishing similar components between the first wheel drive device 10-A and the second wheel drive device 10-B, the names are prefixed with "first, second" and the symbols are appended with "-A". , -B”.

The second wheel drive device 10-B mainly includes a second speed reduction mechanism 18-B, second carriers 20-B and 22-B, a second output member 24-B, and a second base band 26-B. and a second tire 28-B. The second speed reduction mechanism 18-B and the second carriers 20-B and 22-B respectively correspond to the first speed reduction mechanism 18-A and the first carriers 20-A and 22-A of the first wheel drive device 10-A. A common one is used. Here, "common" refers to the components of the referred hardware elements (reduction mechanism, carrier here) between the first wheel drive device 10-A and the second wheel drive device 10-B. It means that not only the shape and size but also the materials of the components are the same.

The second wheel drive device 10-B includes other internal parts arranged on the inner peripheral side of the second output member 24-B and other internal parts arranged on the inner peripheral side of the first output member 24-A. A common one is used. Other internal parts here include the input shaft bearing 44, the main bearing 46, the oil seals 64a and 64d, the seal cap 64b, the shaft cover 64c, and the like. This reduces the number of parts to be managed between the first wheel drive device 10-A and the second wheel drive device 10-B.

FIG. 4(a) is an enlarged view of part of the first wheel drive device 10-A, and FIG. 4(b) is an enlarged view of part of the second wheel drive device 10-B. The second output member 24-B is thicker than the first output member 24-A over the entire range in the axial direction X. As shown in FIG. The thickness here refers to the dimension along the radial direction. In addition, the second output member 24-B has the same inner and outer peripheral shapes and axial dimensions as those of the first output member 24-A. The first output member 24-A and the second output member 24-B have the same shape and axial dimension of the inner periphery means that the taper rate and axial dimension of the outer peripheral tapered surface 50 are the same between them. It is also that it is. The inner peripheral portion of the second output member 24-B has the same radial dimension as that of the first output member 24-A. Further, the second output member 24-B has the same overall axial dimension and material as the first output member 24-A. Here, "having the same shape" means that the contours of the cut surfaces along the axial direction A are the same.

The second baseband 26-B is thicker than the first baseband 26-A over the entire range in the axial direction X. As shown in FIG. In addition, the second baseband 26-B has the same inner and outer peripheral shapes and axial dimensions as those of the first baseband 26-A. The fact that the shape and axial dimension of the inner peripheral portion of the first base band 26-A and the second base band 26-B are the same means that the taper rate and the axial dimension of the inner peripheral tapered surface 52 are the same between them. There is also the fact that they are the same. Further, the second output member 24-B has the same overall axial dimension and material as the first output member 24-A.

The second tire 28-B has an outer diameter larger than that of the first tire 28-A. Further, the second tire 28-B has the same thickness as the first tire 28 in order to match the running resistance with that of the first tire 28. - 特許庁In addition, the second tire 28-B has the same overall shape, axial dimensions, and material as the first tire 28. As shown in FIG.

Here, as described above, in order to obtain the desired characteristics of the speed reduction mechanism 18, it is necessary to manage the tightening force of the base band 26 and the like so that the required starting load of the base band 26 can be obtained. In order to standardize management items among a plurality of wheel driving devices, it is desirable to standardize the tightening force.

With this background, consider a case where tires 28 having different outer diameters are used among a plurality of wheel driving devices as described above. In this case, the outer diameter of the second base band 26-B is increased in accordance with the increase in the outer diameter of the second tire 28-B of the second wheel drive device 10-B. Consider the case of increasing the thickness of In this embodiment, the thickness of the second tire 28-B and the thickness of the first tire 28-A are the same. The thickness of band 26-B is increased.

In this case, if the output member is also shared among a plurality of wheel drive devices, only the thickness of the second base band 26-B is increased, and the second output member 24-B becomes the first output member 24-A. They will have the same thickness. At this time, while the rigidity of the second base band 26-B is increased compared to that of the first base band 26-A, the rigidity of the first output member 24-A and the rigidity of the second output member 24-B become the same.

Here, when a tightening force within a predetermined range for obtaining a required starting load in the first wheel drive device 10-A is also applied to the second base band 26-B and the like of the second wheel drive device 10-B, the following The inventor of the present invention has obtained the knowledge that the phenomenon of First, in the second base band 26-B, when a tightening force in the same predetermined range as that of the first wheel drive device 10-A is applied, the first base band 26-B increases in rigidity. There is a tendency for the amount of deformation toward the outer radial side to decrease relative to the base band 26-A. On the other hand, in the second output member 24-B, as the amount of deformation of the second base band 26-B from the first base band 26-A decreases, it moves radially inward from the first output member 24-A. deformation amount tends to increase. As a result, when the tightening force in the same predetermined range as that of the first wheel drive device 10-A is applied to the second base band 26-B and the second output member 24-B, the first base band 26-A has a higher torque than the first base band 26-A. There is a risk that the starting load of the second baseband 26-B will increase excessively and the required starting load of the baseband 26 cannot be obtained.

(A) Therefore, in the second wheel drive device 10-B of the present embodiment, the thickness of the second base band 26-B is made larger than that of the first base band 26-A. -A, the thickness of the second output member 24-B is made larger than that of A. As a result, when the same predetermined range of tightening force is applied to each wheel driving device 10, the second output member 24-A and the second output member 24-B have the same thickness, compared to the case where the thickness is the same. It is possible to suppress an excessive increase in the amount of deformation of 24-B toward the inner peripheral side in the radial direction. As a result, when the same predetermined range of tightening force is applied to each wheel driving device 10, the starting load of the second base band 26-B is excessively increased from that of the first base band 26-A, and the required starting It becomes easier to avoid situations where the load cannot be obtained.

Here, the present inventor further studied this problem and found that the balance between the rigidity of the output member 24 and the base band 26 is important. In other words, when the rigidity of the second base band 26-B is increased more than that of the first base band 26-A, the deformation amount of the second output member 24-B is suppressed from increasing from that of the first output member 24-A. Therefore, it is important to increase the rigidity of the second output member 24-B in a well-balanced manner in accordance with the increase in the rigidity of the second base band 26-B. In other words, if the rigidity of the output member 24 and the base band 26 are well balanced in each wheel drive device 10, even when the thickness of the base band 26 is increased in accordance with the increase in the outer diameter of the tire 28, the required Each wheel drive device 10 can share a predetermined range of tightening force required to obtain the starting load. In the series of this embodiment, in order to balance the rigidity of the output member 24 and the base band 26 among the plurality of wheel drive devices 10, the thickness ratio of the output member 24 and the base band 26 is set under the following conditions: stipulates.

First, as a premise, the second output member 24-B has the same shape as the first output member 24-A in the inner peripheral portion and the outer peripheral portion. Further, the second baseband 26-B has the same inner and outer peripheral shapes as those of the first baseband 26-A. This is because the rigidity of the output member 24 and the base band 26 cannot be balanced between the first wheel drive device 10-A and the second wheel drive device 10-B if the shapes thereof are changed.

Next, let tb1 [mm] be the thickness of the minimum outer diameter portion 24c where the outer peripheral tapered surface 50 of the output member 24 has the minimum diameter. Let tb2 [mm] be the thickness of the maximum outer diameter portion 24d where the outer peripheral tapered surface 50 of the output member 24 has the maximum diameter. Let ta1 [mm] be the thickness of the small inner diameter portion 26c of the base band 26 that is aligned with the minimum outer diameter portion 24c of the output member 24 in the axial direction X. As shown in FIG. Let ta2 be the thickness of the large inner diameter portion 26d of the baseband 26 that is aligned with the maximum outer diameter portion 24d of the output member 24 in the axial direction X. As shown in FIG.

At this time, the thickness tb1 of the minimum outer diameter portion 24c of the output member 24 is set to be 1.1 times or more and 1.2 times or less the thickness ta1 of the small inner diameter portion 26c of the base band 26 . Also, the thickness tb2 of the maximum outer diameter portion 24d of the output member 24 is set to be 1.5 times or more and 2.0 times or less the thickness ta2 of the large inner diameter portion 26d of the base band 26 . These numerical conditions are set based on the results of experimental studies by the inventors. This condition is set so as to be individually satisfied by both the first wheel drive device 10-A and the second wheel drive device 10-B. In other words, when the thickness of the second baseband 26-B is greatly increased from that of the first baseband 26-A, the thickness of the second output member 24-A is greater than that of the first output member 24-A within a range corresponding to the thickness of the second baseband 26-B. By increasing the thickness of the output member 24-B, the rigidity of the output member 24 and the base band 26 are balanced.

When the thickness tb1 of the output member 24 of either the first wheel drive device 10-A or the second wheel drive device 10-B is less than 1.1 times the thickness ta1 of the baseband 26, the output compared with the baseband 26 The stiffness of member 24 becomes excessively small. As a result, when the tightening force within the same predetermined range is applied to the output member 24 and the base band 26 in each wheel drive device 10, the output member 24 of the wheel drive device 10 that does not satisfy this condition is radially inwardly displaced. The amount of deformation becomes excessively large, and there is a risk that the required starting load cannot be obtained. The same applies when the thickness tb2 of the output member 24 of either the first wheel drive device 10-A or the second wheel drive device 10-B is less than 1.5 times the thickness ta2 of the base band 26. FIG.

When the thickness tb1 of the output member 24 of either the first wheel drive device 10-A or the second wheel drive device 10-B is more than 1.2 times the thickness ta1 of the baseband 26, the output compared with the baseband 26 The stiffness of member 24 becomes too great. As a result, when the tightening force within the same predetermined range is applied to the output member 24 and the base band 26 in each wheel drive device 10, the output member 24 of the wheel drive device 10 that does not satisfy this condition is radially inwardly displaced. The amount of deformation becomes excessively small, and there is a risk that the required starting load cannot be obtained. The same applies when the thickness tb2 of the output member 24 of either the first wheel drive device 10-A or the second wheel drive device 10-B is more than 2.0 times the thickness ta2 of the base band 26. FIG.

On the other hand, when this condition is satisfied, when the same predetermined range of tightening force is applied to the baseband 26 and the output member 24 in each wheel drive device 10, the thickness of the baseband 26 and the output member 24 of each wheel drive device 10 It becomes easier to obtain the required starting load of the baseband 26 regardless of the change. As a result, even if the baseband 26 and the output member 24 have the same inner and outer peripheral shapes, and the thickness of the baseband 26 is changed among the plurality of wheel drive devices 10 that share the speed reduction mechanism 18, the required It is possible to standardize the tightening force range necessary to obtain the starting load of

Further, from the viewpoint of the first wheel drive device 10-A that satisfies this condition, the second wheel has the same inner and outer peripheral shapes of the base band 26 and the output member 24, and has the speed reduction mechanism 18 in common. Even if the thickness of the base band 26 is changed with the driving device 10-B, the tightening force range required to obtain the required starting load can be shared.

Exemplary embodiments of the present invention have been described above in detail. All of the above-described embodiments merely show specific examples for carrying out the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of constituent elements can be made without departing from the spirit of the invention defined in the claims. It is possible. In the above-described embodiment, descriptions such as "of the embodiment", "in the embodiment", etc. are added to the contents that allow such design changes. Changes are not unacceptable. Moreover, the hatching attached to the cross section of the drawing does not limit the material of the hatched object.

Although an example in which the wheel drive device 10 is incorporated in a carriage has been described, the counterpart to which it is incorporated is not particularly limited. Moreover, although the track-guided carriage has been described as an example of this carriage, it may be a trackless carriage.

Although the speed reduction mechanism 18 has been described as an eccentric swing speed reduction mechanism, the type is not particularly limited. For example, any one of a planetary gear mechanism, a parallel shaft gear mechanism, an orthogonal shaft gear reduction mechanism, a flexure mesh type reduction mechanism, and the like may be included. In the case of the eccentric oscillating type reduction mechanism, in addition to the center crank type in which the input shaft (eccentric body shaft) is arranged at the axial center of the internal gear, there are also multiple A distribution type in which an input shaft (eccentric body shaft) is arranged may be used.

Although the example in which the output member 24 also serves as the casing of the speed reduction mechanism 18 has been described, the present invention is not limited to this. For example, the output member 24 may be arranged on the outer peripheral side of the casing of the speed reduction mechanism 18 and rotated by the output shaft of the speed reduction mechanism 18 .

It is not essential to make the thickness of the tire 28 the same between the first wheel drive devices 10-A and 10-B. From the viewpoint of obtaining the aforementioned effect (A), the thickness of the second base band 26-B is greater than that of the first base band 26-A, and the thickness of the second output member 24-B is greater than that of the first output member 24-A. It suffices if the condition that the thickness of is increased.

DESCRIPTION OF SYMBOLS 10... 1st wheel drive device, 10... 2nd wheel drive device, 18... Reduction mechanism, 24... Output member, 24a... End surface part, 24c... Minimum outer diameter part, 24d... Maximum outer diameter part, 26... Base band, 26a... flange portion, 26c... small inner diameter portion, 26d... large inner diameter portion, 28... tire, 50... tapered surface.

Claims (5)

a deceleration mechanism that decelerates rotation transmitted from the drive source;
a cylindrical output member to which the rotation reduced by the reduction mechanism is transmitted;
a base band fitted on the output member;
A wheel drive device comprising: a tire attached to the base band;
A tapered surface is provided on an outer peripheral surface of the output member and an inner peripheral surface of the base band,
the base band is fitted onto the output member by an interference fit while the tapered surfaces of the base band and the output member are in contact with each other ;
tb1 is the thickness of the minimum outer diameter portion at which the tapered surface of the output member has the minimum diameter, tb2 is the thickness of the maximum outer diameter portion at which the tapered surface of the output member has the maximum diameter, and the minimum outer diameter of the base band. When the thickness of the small inner diameter portion axially aligned with the radial portion is ta1, and the thickness of the large inner diameter portion axially aligned with the maximum outer diameter portion of the base band is ta2,
The thickness tb1 is set to 1.1 times or more and 1.2 times or less the thickness ta1,
The thickness tb2 is a wheel driving device set to be 1.5 times or more and 2.0 times or less of the thickness ta2. the base band has a flange portion extending radially inwardly from one axial end thereof;
2. The wheel driving device according to claim 1, wherein the axial end face portion of the output member and the flange portion are fastened with bolts. The axial tightening force applied to the base band and the output member is such that the starting load of the base band is 4 kgf or more and 10 kgf or less under the condition that the power transmission path between the speed reduction mechanism and the drive source is disconnected. 3. The wheel drive device according to claim 1 or 2 , which is set so as to be: a first wheel drive device, which is the wheel drive device according to any one of claims 1 to 3 ;
A second wheel drive device, which is the wheel drive device according to any one of claims 1 to 3 ,
The second wheel drive device is a series of wheel drive devices having a tire having an outer diameter larger than that of the tire of the first wheel drive device and a speed reduction mechanism common to the speed reduction mechanism of the first wheel drive device. ,
The second wheel drive device,
a baseband in which the thickness of each of the small inner diameter portion and the large inner diameter portion is greater than that of the baseband of the first wheel drive device;
A series of wheel drive devices comprising: an output member in which each of the minimum outer diameter portion and the maximum outer diameter portion is thicker than the output member of the first wheel drive device. The baseband of the second wheel drive device has the same shape as the baseband of the first wheel drive device in inner and outer peripheral portions,
5. The series of wheel drive devices according to claim 4 , wherein the output member of said second wheel drive device has the same shape of inner and outer peripheral portions as those of said output member of said first wheel drive device.

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