Dimeter variable wheel and wheel drive unit

Abstract

To widen a change range of a wheel diameter of a diameter change wheel.SOLUTION: A diameter change wheel 20 comprises: a hub member 22 rotating around an axis of an axle O; a plurality of arm members 21A to 21F each having one end side connected to the hub member; a rotation member 23 rotatively driven around the same axis as the axle by a driving force of an external drive source; a diameter change mechanism 24 changing a radial position of each wheel on the other end sides of the plurality of arm members by the relative rotation of the rotation member with respect to the hub member; and a wheel outer peripheral member 26 supported by the other end sides of the plurality of arm members. The one end sides of the plurality of arm members are each connected to the hub member to be rotatable around an arm shaft 24a parallel with the axle, so that the diameter change mechanism changes the radial position of each wheel of the other end sides of the plurality of arm members by rotating the plurality of arm members around the arm shaft by the relative rotation of the rotation member with respect to the hub member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a variable diameter wheel and a wheel drive device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, variable diameter wheels that are capable of changing the diameter of the wheels are known and are used in vehicles, wheelchairs, bicycles, suitcases, baby strollers, and the like.

[0003] For example, Patent Document 1 discloses a variable diameter wheel in which a rim (wheel outer peripheral member) is connected to a hub (hub member) arranged coaxially with the axle by a number of retractable arms (arm members) extending in the wheel radial direction. The rim is configured to form an annular shape by connecting a number of arcuate segments arranged along the circumferential direction of the wheel with connecting segments, and is configured so that the rim circumference (wheel circumference) can be changed in response to changes in the wheel diameter. Each arcuate segment is attached to the radially outer end of a retractable arm. Each retractable arm is provided with a lug that fits into each curved groove formed in a disk (rotating member) coaxial with the hub. The lug of each retractable arm moves along each curved groove of the disk due to relative rotation of the disk with respect to the hub, causing each retractable arm to slide in the wheel radial direction relative to the hub, changing the diameter of the wheel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-531843 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, because conventional diameter-variable wheels change the wheel diameter by linearly moving each arm member along the wheel diameter direction, the radially inner ends of each arm member move toward the axle when the wheel diameter is reduced. Therefore, it is necessary to avoid mutual interference near the axle, making it difficult to sufficiently reduce the wheel diameter, and as a result, it is difficult to greatly change the wheel diameter. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, one aspect of the present invention is a diameter variable wheel comprising a hub member that rotates around the axis of an axle, a plurality of arm members having one end sides connected to the hub member, a rotating member that is driven to rotate coaxially with the axle by the driving force of an external drive source, a diameter change mechanism that changes the wheel radial position of each of the other end sides of the plurality of arm members by relative rotation of the rotating member with respect to the hub member, and a wheel outer periphery member supported on the other end sides of the plurality of arm members, wherein the one end sides of the plurality of arm members are each connected to the hub member so as to be freely rotatable around an arm axis parallel to the axle, and the diameter change mechanism changes the wheel radial position of each of the other end sides of the plurality of arm members by rotating the rotating member relative to the hub member. In this aspect, the relative rotation of the rotating member with respect to the hub member changes the radial position of the wheel periphery member supported on the other end side of the multiple arm members, and the diameter of the diameter-variable wheel is changed. At this time, in this aspect, the multiple arm members rotate (rotate) around the arm axis, and the wheel periphery member supported on the other end side of the multiple arm members rotates around the arm axis, and the wheel radial position of the wheel periphery member is changed. With such rotation of the arm members, it is possible to change the wheel diameter without bringing one end side of each arm member close to the axle when reducing the diameter. Therefore, it is possible to reduce the wheel diameter while preventing the one end sides of each arm member from interfering with each other near the axle. Therefore, it is possible to change the wheel diameter more than before, and a diameter-variable wheel with a wide range of wheel diameter changes can be realized.

[0007] The diameter variable wheel may further include a biasing force applying portion that applies a biasing force in a direction in which each wheel radial direction position on the other end side of the arm members moves outward in the wheel radial direction. In general, when a diameter variable wheel is used, an external force acts on the wheel outer periphery member of the diameter variable wheel in the radial direction toward the inside of the wheel. For example, when a diameter variable wheel is used as a wheel of a vehicle, the wheel outer periphery member that is grounded on the road surface receives an external force from the road surface toward the inside of the wheel radial direction according to the vehicle weight. Also, for example, when a diameter variable wheel is used as a belt pulley, an external force from a stretched belt toward the inside of the wheel radial direction according to the belt tension is received. Therefore, when the wheel diameter is to be enlarged by moving the wheel radial position of the wheel outer periphery member radially outward by rotating the arm member while the diameter variable wheel is in use, it is necessary to rotate the arm member against the external force acting on the wheel outer periphery member. Therefore, when the wheel diameter is enlarged while the diameter variable wheel is in use, the rotation load of the arm member is large, and the drive load of the external drive source that rotates and drives the rotating member for rotating the arm member is also large. According to this aspect, the biasing force applying unit applies a biasing force in a direction that moves each wheel radial direction position on the other end side of the multiple arm members outward in the wheel radial direction. Therefore, when the wheel diameter is expanded against an external force acting on the wheel outer periphery member while the diameter variable wheel is in use, the arm members can be rotated with the assistance of the biasing force of the biasing force applying unit. As a result, the driving load of the external driving source that rotates the rotating member to rotate the arm members can be reduced. The biasing force provided by the biasing force application unit increases the drive load of the external drive source when the wheel diameter is reduced during use of the diameter-variable wheel. However, when the wheel diameter is reduced, the drive load of the external drive source is reduced by the external force acting on the wheel outer periphery member, so the biasing force provided by the biasing force application unit does not pose a problem in terms of the drive load of the external drive source.

[0008] In addition, in the variable diameter wheel, the wheel outer periphery member may be configured such that a plurality of arc members each supported on the other end side of the plurality of arm members are arranged along the circumferential direction of the variable diameter wheel, and adjacent arc members are connected to each other so as to be able to move relatively in the circumferential direction of the variable diameter wheel, forming a ring shape. According to this aspect, the outer periphery of the diameter variable wheel is formed by an annular wheel outer periphery member made of multiple arc members arranged in the wheel circumferential direction, whether the wheel is contracted or expanded. Therefore, it is possible to realize a diameter variable wheel in which there are no discontinuous parts (parts without a wheel outer periphery member) on the wheel outer periphery, whether the wheel is contracted or expanded.

[0009] In the variable diameter wheel, the hub member may be driven to rotate about the axis of the axle by a driving force from a second external driving source. The uses of the variable diameter wheel can be roughly divided into so-called drive wheels and driven wheels. The variable diameter wheel of this embodiment can be used as a drive wheel because the hub member can be rotationally driven around the axis of the axle by the driving force from the second external driving source.

[0010] Another aspect of the present invention is a wheel drive device comprising the above-mentioned diameter variable wheel, an external drive source provided outside the diameter variable wheel for rotating the rotating member of the diameter variable wheel, and a diameter control unit for controlling the external drive source based on rotational speed information and target diameter information of the diameter variable wheel so that the diameter of the diameter variable wheel becomes the target diameter. According to this aspect, in a wheel drive device that drives the wheel diameter of a diameter variable wheel to change the wheel diameter, the change range of the wheel diameter of the diameter variable wheel can be widened.

[0011] Furthermore, yet another aspect of the present invention is a wheel drive device comprising the above-mentioned diameter variable wheel, a first external drive source provided outside the diameter variable wheel and rotating and driving the rotating member of the diameter variable wheel, a second external drive source provided outside the diameter variable wheel and rotating and driving the hub member of the diameter variable wheel, a speed control unit that controls the second external drive source based on the target speed information so that the rotational speed of the diameter variable wheel becomes a target speed, and a diameter control unit that controls the external drive source based on the rotational speed information and target diameter information of the diameter variable wheel so that the diameter of the diameter variable wheel becomes the target diameter. According to this aspect, in a wheel drive device that rotationally drives a variable diameter wheel by rotationally driving a hub member by a second external drive source, the range in which the wheel diameter of the variable diameter wheel can be changed can be made wider than before.

[0012] In the wheel drive device, the diameter control unit may control the external drive source so that the rotating member is rotated at the same rotational speed as the rotational speed of the hub member after the diameter of the diameter variable wheel becomes a target diameter. According to this aspect, after the diameter of the diameter-variable wheel becomes the target diameter, the external drive source is controlled so that the rotating member is rotationally driven at the same rotational speed as the hub member. Therefore, even while the hub member is being rotationally driven by the second external drive source (i.e., while the diameter-variable wheel is being rotationally driven), the rotating member does not rotate relative to the hub member, and the diameter-variable wheel can be rotationally driven while maintaining the target diameter. In addition, a method other than the present embodiment can be adopted as a method for maintaining the diameter of the variable diameter wheel at the target diameter while the hub member is being rotationally driven by the second external driving source (while the variable diameter wheel is being rotationally driven). For example, a method in which the rotating member and the hub member are fixed to each other, and the rotating member is switched so as to rotate integrally with the hub member, and then the hub member, the rotating member, and all of the components of the variable diameter wheel that rotate integrally therewith are rotationally driven by the second external driving source. However, this method requires the second external driving source to have a rotational driving force that not only rotates the hub member and the members that rotate integrally therewith, but also the rotating member and the members that rotate integrally therewith, and therefore requires a large driving source as the second external driving source. In contrast, in this embodiment, while the hub member is being rotationally driven by the second external driving source (while the diameter variable wheel is being rotationally driven), the rotating member is rotationally driven by the external driving source (a driving source different from the second external driving source) at the same rotational speed as the hub member. Therefore, among the components of the diameter variable wheel, the rotating member and the members that rotate integrally therewith are rotationally driven not by the second external driving source that rotationally drives the hub member, but by the external driving source that applies the rotational driving force for changing the wheel diameter. Therefore, the rotational driving force required for the second external driving source that rotationally drives the hub member (rotating the diameter variable wheel) can be reduced compared to the case where the above-mentioned method is adopted. This makes it possible to use a smaller driving source for the second external driving source. Alternatively, if the same driving source as that used in the case where the above-mentioned method is adopted is used as the second external driving source, the diameter variable wheel can be rotationally driven with a larger driving force.

[0013] The wheel drive device may further include a switching mechanism that switches between a fixed state in which the hub member and the rotating member rotate integrally, and an unfixed state in which the hub member and the rotating member are rotatable relative to one another. According to this aspect, the diameter of the variable diameter wheel can be changed by an external drive source by switching the hub member and the rotating member to an unlocked state in which they are rotatable relative to one another. Also, by switching the hub member and the rotating member to a locked state in which they rotate together, it is possible to stably prevent the diameter of the variable diameter wheel from changing while it is being driven to rotate. Furthermore, by applying a rotational driving force from an external driving source when the hub member and the rotating member are switched to a fixed state in which they rotate integrally, the hub member, the rotating member, and the components of the variable diameter wheel that rotate integrally therewith can be rotationally driven by both the external driving source and the second external driving source. As a result, the rotational driving force required for the second external driving source that rotationally drives the hub member (rotating the variable diameter wheel) can be further reduced. This makes it possible to use a smaller driving source as the second external driving source. Alternatively, if the same driving source as in the case of employing the above-mentioned method is used as the second external driving source, the variable diameter wheel can be rotationally driven with a larger driving force. Effect of the Invention

[0014] According to the present invention, the range over which the wheel diameter of the variable diameter wheel can be changed can be widened. [Brief description of the drawings]

[0015] [Figure 1] FIG. 4 is a front view of the wheel according to the embodiment with the diameter enlarged. [Diagram 2] FIG. 4 is a front view of the wheel with a reduced diameter. [Diagram 3] FIG. 4 is a perspective view for explaining a diameter changing mechanism for changing the diameter of the wheel. [Figure 4] FIG. 4 is a perspective view of the wheel as viewed from the side to which the driving force of the diameter-changing motor is input. [Diagram 5] FIG. 4 is a perspective view of the wheel as viewed from the side to which the driving force of the wheel drive motor is input. [Figure 6] FIG. 2 is a perspective view showing one ground contact arc member that constitutes the ground contact arc of the wheel. [Figure 7] 1A is a perspective view showing a state in which two ground contact arc members are connected to each other when the wheel diameter is reduced, and FIG. 1B is a perspective view showing a state in which two ground contact arc members are connected to each other when the wheel diameter is expanded. [Figure 8] 1 is a perspective view showing an example of a wheel drive device according to an embodiment; [Figure 9] FIG. 2 is a control block diagram for explaining main control contents of the wheel drive device. [Figure 10] 4A is a graph showing an example of the control content of a speed control unit in the wheel drive device, and FIG. 4B is a graph showing an example of the control content of a diameter control unit in the wheel drive device. [Figure 11] FIG. 13 is a front view of a modified example in which the diameter of the wheel is reduced. [Figure 12] FIG. 13 is an exploded perspective view showing an example in which a wheel drive motor and a diameter changing motor are arranged on the wheel axle and directly connected to a hub member and a drive gear, respectively. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a variable diameter wheel according to the present invention will be described with reference to the drawings. In the following description, the wheel of this embodiment will be described as a driving wheel that receives the driving force of a wheel drive motor, which is a second external driving source for driving the wheels, and is rotated. However, the wheel of this embodiment may be used as a driven wheel that rotates without receiving the driving force of the wheel drive motor, depending on the application or mode of use.

[0017] Examples of applications or usage as drive wheels include drive wheels for self-propelled vehicles such as automobiles, bicycles, electric wheelchairs, and electric carts, and drive wheels for drive transmission devices such as drive pulleys that tension the belt of a belt drive device. In addition, examples of applications or usage of the driven wheel include a driven wheel of a self-propelled vehicle or a non-self-propelled vehicle (non-self-propelled wheelchair, stroller, carry case, etc.), a driven wheel of a drive transmission device such as a driven pulley that tensions the belt of a belt drive device, etc.

[0018] FIG. 1 is a front view of a wheel 20 according to this embodiment with its diameter enlarged. FIG. 2 is a front view of the wheel 20 of this embodiment with its diameter reduced. FIG. 3 is a perspective view for explaining a diameter changing mechanism for changing the diameter of the wheel 20 of this embodiment. FIG. 4 is a perspective view of the wheel 20 of this embodiment as viewed from the side to which the driving force of the diameter-changing motor is input. FIG. 5 is a perspective view of the wheel 20 of this embodiment as viewed from the side to which the driving force of the wheel drive motor is input.

[0019] In FIG. 3, in order to show the internal structure of the wheel 20, some of the components (first hub plate 22a, first arm plate 21a, etc.) are shown by dashed lines as transparent, and other components (ground arc 26, etc.) are omitted. Also, in Figs. 4 and 5, illustration of some components (such as the ground arc 26) is omitted.

[0020] The wheel 20 of this embodiment comprises a hub member 22 that rotates around the axle O, six arm members 21A to 21F whose radially inner end sides (one end sides) are connected to the hub member 22, a drive gear 23 as a rotating member that is driven to rotate coaxially with the axle O by the driving force of a diameter-changing motor which is an external drive source, a diameter-changing mechanism 24 that changes the wheel radial position of each of the radially outer end sides (other end sides) of the six arm members by the relative rotation of the drive gear 23 with respect to the hub member 22, and a ground contact arc 26 as a wheel outer periphery member supported on the radially outer end sides of the six arm members.

[0021] The hub member 22 has two disk-shaped hub plates 22a, 22b arranged to face each other with a predetermined gap therebetween. The hub plates 22a, 22b are configured to rotate around the axis of the axle O integrally with each other.

[0022] 1 and 2, the first hub plate 22a of the two hub plates 22a, 22b is provided with an opening 22c that opens in a circular shape centered on the axle O. A drive gear 23 is inserted into this opening 22c.

[0023] A wheel drive pulley 28 is attached to the second hub plate 22b of the two hub plates 22a, 22b as a connection part connected to a wheel drive motor which is a second external drive source for driving the wheels. The wheel drive pulley 28 is provided coaxially with the second hub plate 22b so as to rotate integrally with the second hub plate 22b, and a drive transmission belt 14 connected to a wheel drive motor of a drive device described below is stretched over the wheel drive pulley 28. As a result, the hub member 22 is driven to rotate coaxially with the axle O by the driving force of the wheel motor of the drive device.

[0024] The six arm members 21A to 21F are provided with two long plate-like arm plates 21a, 21b facing each other at a predetermined interval, and are configured so that the arm plates 21a, 21b move integrally with each other. The radially inner ends of the six arm members 21A to 21F are attached to arm gears 24A to 24F (described later) attached to the hub member 22 so as to be sandwiched between the two arm plates 21a, 21b. As a result, the six arm members 21A to 21F are configured to rotate integrally with the arm gears 24A to 24F around the rotation shafts (arm shafts) 24a of the arm gears 24A to 24F, respectively.

[0025] In this embodiment, the arm members 21A-21F are all identical in configuration, but it is also possible to combine and use arm members having different configurations (shapes, dimensions, etc.) The number of arm members 21A-21F may be five or less, or seven or more, but is preferably three or more, and more preferably six or more.

[0026] The drive gear 23 is disposed coaxially with the axle O between the two hub plates 22a, 22b, and disposed so as to mesh with all of the three idler gears 25A to 25C (described later) attached to the hub member 22. A diameter-changing drive pulley 27 is attached to the drive gear 23 as a connection part connected to a diameter-changing motor, which is an external drive source. The diameter-changing drive pulley 27 is disposed coaxially with the drive gear 23 so as to rotate integrally with the drive gear 23, and a drive transmission belt 13 connected to a diameter-changing motor of a drive device (described later) is stretched over the diameter-changing drive pulley 27. As a result, the drive gear 23 is rotated coaxially with the axle O by the driving force of the diameter-changing motor of the drive device, and the driving force is transmitted to the three idler gears 25A to 25C.

[0027] The diameter changing mechanism 24 is made up of six arm gears 24A to 24F and three idler gears 25A to 25C. The arm gears 24A to 24F and the idler gears 25A to 25C are disposed between two hub plates 22a, 22b, and both shaft ends of each gear are supported by the hub plates 22a, 22b, respectively, so as to be rotatable (rotatable on their own axes).

[0028] The three idler gears 25A-25C are arranged to surround the periphery of the axle O, and each of the idler gears 25A-25C is arranged to mesh with the drive gear 23 that is arranged coaxially with the axle O. The six arm gears 24A-24F are arranged to surround the periphery of the axle O, outward in the wheel radial direction from the idler gears 25A-25C. The six arm gears 24A-24F are arranged so that two arm gears 24A-24F mesh with each idler gear 25A-25C.

[0029] In the diameter changing mechanism 24, the driving gear 23 is driven to rotate coaxially with the axle O by the driving force of the diameter changing motor of the driving device, and when the driving gear 23 rotates relative to the hub member 22, the three idler gears 25A-25C rotate (spin) around the respective gear shafts 25a. As a result, the six arm gears 24A-24F meshed with the three idler gears 25A-25C also rotate (spin) around the respective gear shafts 24a. As a result, the six arm members 21A-21F attached to the respective arm gears 24A-24F rotate around the gear shafts 24a of the respective arm gears 24A-24F.

[0030] The ground arc 26 is composed of ground arc members 26A to 26F, which are six arc members supported on the radially outer end sides (other end sides) of the six arm members 21A to 21F, respectively. The six ground arc members 26A to 26F, with odd-numbered ground arc members 26A, 26C, and 26E and even-numbered ground arc members 26B, 26D, and 26F, are mirror images of each other with respect to a plane perpendicular to the axle, and each includes a fixing opening 26a and a sliding elongated hole 26b, like the ground arc member 26A shown in FIG. 6.

[0031] The fixing openings 26a of each of the ground arc members 26A to 26F are inserted with mounting pins 21c (see FIG. 3) that are sandwiched between the two arm plates 21a, 21b of the corresponding arm members 21A to 21F and attached near the ends on the radially outer side of the two arm plates 21a, 21b. Also, the sliding slots 26b of each of the ground arc members 26A to 26F are inserted with mounting pins 21c of the arm members 21F, 21A, 21B, 21C, 21D, and 21E that are adjacent to the arm members 21A to 21F attached by the mounting pins 21c that pass through the fixing openings 26a of the same ground arc members 26A to 26F, as shown in FIGS. 7(a) and 7(b).

[0032] 1 and 2, the ground contact arc 26 of this embodiment is formed in such a manner that the ground contact arc members 26A-26F are arranged along the circumferential direction of the wheel 20 to form a ring shape. Then, as shown in Figures 7(a) and 7(b), the ground contact arc members 26A-26F adjacent to each other are configured to be able to move relatively to each other in the circumferential direction of the wheel 20 (the circumferential direction centered on the axle O).

[0033] Next, the configuration and operation for changing the diameter of the wheel 20 in this embodiment will be described. First, a case will be described in which the diameter of the wheel 20 is changed while the rotation of the wheel 20 (the rotation of the hub member 22) is stopped.

[0034] In this case, when the driving gear 23 is driven to rotate coaxially with the axle O by the driving force of a diameter-changing motor of a driving device described later, the driving gear 23 rotates relative to the hub member 22 in a non-rotating state. This causes the three idler gears 25A-25C attached to the hub member 22 to rotate (spin) about their respective gear shafts 25a, and the six arm gears 24A-24F also rotate (spin) about their respective gear shafts 24a. As a result, the six arm members 21A-21F rotate (spin) about the gear shafts 24a of the arm gears 24A-24F.

[0035] When the six arm members 21A-21F rotate around the gear shaft 24a of each arm gear 24A-24F, the radial position of the radially outer end of each arm member 21A-21F changes. Accordingly, the radial position of each ground contact arc member 26A-26F of the ground contact arc 26 supported on the radially outer end of each arm member 21A-21F also changes, and each ground contact arc member 26A-26F moves toward or away from the axle O.

[0036] The six ground contact arc members 26A-26F in this embodiment are connected to each other by the slide long holes 26b, and can move relatively to each other in the circumferential direction of the wheel 20. Therefore, the distance between the ground contact arc members 26A-26F in the wheel circumferential direction can be shortened or expanded as the ground contact arc members 26A-26F approach or move away from the axle O. As a result, it is possible to achieve a state in which no discontinuous portion (a portion without a wheel periphery member) exists on the wheel periphery, whether the wheel is contracted or expanded.

[0037] When the diameter of the wheel 20 is to be enlarged, the driving gear 23 is driven to rotate in a reverse direction A (the rotation direction of the wheel 20 (hub member 22) when the wheel drive device 1 moves backward in this embodiment) by the driving force of the diameter changing motor. As a result, as shown in FIG. 1, the ends on the radially outer ends of the arm members 21A to 21F rotate in a direction away from the axle O, and the ground contact arc members 26A to 26F move away from the axle O, and the diameter of the wheel 20 is enlarged.

[0038] On the other hand, when the diameter of the wheel 20 is reduced, the driving gear 23 is rotated in a forward direction B (the rotation direction of the wheel 20 (hub member 22) when the wheel drive device 1 moves forward in this embodiment) by the driving force of the diameter changing motor. As a result, as shown in Fig. 2, the ends on the radially outer side of the arm members 21A to 21F rotate in a direction approaching the axle O, and the ground contact arc members 26A to 26F move closer to the axle O, thereby reducing the diameter of the wheel 20.

[0039] In the wheel 20 of this embodiment, the diameter of the wheel 20 can be changed even while the wheel 20 (hub member 22) is rotating.

[0040] In detail, when hub member 22 is rotationally driven by the driving force of the wheel drive motor and wheel 20 is rotating, the three idler gears 25A-25C rotate (revolve) around drive gear 23 which is coaxial with axle O in accordance with the rotation of hub member 22. At this time, if drive gear 23 is rotationally driven at the same rotational speed as hub member 22, drive gear 23 does not rotate relative to hub member 22, so that three idler gears 25A-25C do not rotate (spin) around each gear shaft 25a and the diameter of wheel 20 is maintained.

[0041] On the other hand, if the drive gear 23 is rotationally driven at a rotational speed slower than the rotational speed of the hub member 22, the drive gear 23 rotates relative to the hub member 22 in the reverse direction A. As a result, the three idler gears 25A-25C rotate (spin) around the respective gear shafts 25a, and the diameter of the wheel 20 is enlarged. On the other hand, if the drive gear 23 is rotationally driven at a rotational speed faster than the rotational speed of the hub member 22, the drive gear 23 rotates relative to the hub member 22 in the forward direction B. As a result, the three idler gears 25A-25C rotate (spin) around the respective gear shafts 25a, and the diameter of the wheel 20 is reduced.

[0042] Next, the wheel drive device 1 equipped with the wheel 20 of this embodiment will be described. FIG. 8 is a perspective view showing an example of the wheel drive device 1 of the present embodiment. In addition, in FIG. 8, illustration of some components (such as the drive transmission belts 13 and 14) is omitted.

[0043] The wheel drive device 1 of this embodiment is used, for example, as a small rover for traveling on rough ground. Note that components may be added to the wheel drive device 1 as appropriate according to the function of the final product in which the wheel drive device 1 is used. Also, the configurations of the drive source, drive transmission mechanism, wheels 20, and the like that constitute the wheel drive device 1 may be changed as appropriate according to the function of the final product in which the wheel drive device 1 is used.

[0044] The wheel drive device 1 of this embodiment is mainly composed of the above-mentioned wheel 20, a drive device 10 to which the wheel 20 is attached, and a control device 30 that controls the wheel drive device 1.

[0045] The drive unit 10 includes a diameter-changing motor 11 as a first external drive source that rotates and drives the drive gear 23 of the wheel 20, a wheel drive motor 12 as a second external drive source that rotates and drives the hub member 22 of the wheel 20, and a support frame 15 that supports the axle of the wheel 20 and the components of the drive unit 10 (motors 11, 12, etc.).

[0046] The diameter changing motor 11 is supported by a first frame portion 15a constituting the support frame 15, and a motor pulley 16 is attached to the motor shaft of the diameter changing motor 11. A drive transmission belt 13 is stretched around the motor pulley 16, and is passed around a diameter changing drive pulley 27 that rotates integrally with a drive gear 23 of the wheel 20.

[0047] The wheel drive motor 12 is supported by a second frame portion 15b constituting the support frame 15, and a motor pulley 17 is attached to the motor shaft of the wheel drive motor 12. A drive transmission belt 14 is stretched around the motor pulley 17, and is passed around a wheel drive pulley 28 that rotates integrally with a hub member 22 (second hub plate 22b) of the wheel 20.

[0048] The control device 30 of the wheel drive device 1 is composed of various hardware such as a CPU, RAM, and ROM, and realizes desired functions or control operations by the CPU executing various software such as various computer programs and various data stored in the ROM, etc. The control device 30 is supported by the support frame 15 of the drive device 10 (see FIG. 8), and is wired to the diameter changing motor 11 and wheel drive motor 12 of the drive device 10.

[0049] FIG. 9 is a control block diagram for explaining main control contents of the wheel drive device 1 of this embodiment. The control device 30 of this embodiment is made up of a speed control section 31 that controls the rotation speed of the wheels 20, a diameter control section 32 that controls the diameter of the wheels 20, and a main control section 33 that supervises overall control.

[0050] The speed control unit 31 controls the wheel drive motor 12 in accordance with a control command from the main control unit 33. For example, the speed control unit 31 controls the wheel drive motor 12 so that the rotational speed of the wheel 20 (hub member 22) becomes a target speed, based on target speed information included in the control command from the main control unit 33. The speed control unit 31 of this embodiment receives feedback of rotational speed information from a rotational speed detection unit provided in the wheel drive motor 12, and feedback controls the rotational speed of the wheel 20 (hub member 22).

[0051] The diameter control unit 32 controls the diameter changing motor 11 in accordance with a control command from the main control unit 33. For example, the diameter control unit 32 controls the diameter changing motor 11 based on the rotational speed information of the wheel 20 from the speed control unit 31 and the target diameter information included in the control command from the main control unit 33 so that the diameter of the wheel 20 becomes the target diameter.

[0052] FIG. 10(a) is a graph showing an example of the control content of the speed control unit 31 in this embodiment. FIG. 10(b) is a graph showing an example of the control contents of the diameter control unit 32 in this embodiment.

[0053] 10(a), the speed control unit 31 starts the wheel drive motor 12 in accordance with a control command from the main control unit 33, and controls the wheel drive motor 12 so that the rotational speed (rotational angular velocity) ω of the wheel 20 (hub member 22) becomes the target speed. Following this, the diameter control unit 32 also controls the diameter changing motor 11 based on the rotational speed information of the wheel 20 from the speed control unit 31 so that the rotational speed of the drive gear 23 becomes the same speed (target speed A) as the rotational speed (rotational angular velocity) ω of the wheel 20 (hub member 22). As a result, the wheel 20 can be rotated at the target speed in accordance with the control command from the main control unit 33 while maintaining the diameter.

[0054] In this embodiment, while the wheel 20 (hub member 22) is being driven to rotate by the wheel drive motor 12, the drive gear 23 is driven to rotate by the diameter changing motor 11 at the same rotation speed as the hub member 22. Therefore, among the components of the wheel 20, the drive gear 23 and the members that rotate integrally therewith are driven to rotate by the diameter changing motor 11 for changing the wheel diameter, not by the wheel drive motor 12 that drives the hub member 22 to rotate. Therefore, the rotational drive force required of the wheel drive motor 12 can be reduced, compared to the case where the drive gear 23 and the members that rotate integrally therewith are also driven to rotate by the wheel drive motor 12. This makes it possible to use a smaller drive source for the wheel drive motor 12. Alternatively, the wheel 20 can be driven to rotate with a larger drive force.

[0055] Here, when a control command to reduce the diameter of the wheel 20 is input from the main control unit 33 to the diameter control unit 32 while the wheel 20 is rotating at the target speed, the diameter control unit 32 controls the diameter changing motor 11 so that the diameter of the wheel 20 becomes the target diameter related to the control command. Specifically, as shown in Fig. 10(b), the diameter control unit 32 controls the diameter changing motor 11 so that the rotation speed of the drive gear 23 is driven at the target speed A (a rotation speed that is faster than the rotation speed information of the wheel 20 from the speed control unit 31 by a specified speed) for a predetermined time (6 seconds in the example of Fig. 10(b)) according to the target diameter related to the control command.

[0056] As a result, the drive gear 23 is driven at a rotational speed relatively faster than the rotational speed of the wheel 20 (hub member 22) for a predetermined period of time, and as a result, the three idler gears 25A-25C meshed with the drive gear 23 rotate (spin) in the forward direction around each gear shaft 25a. As a result, as shown in Fig. 2, the radially outer ends of each of the arm members 21A-21F rotate in a direction approaching the axle O, and each of the ground contact arc members 26A-26F moves closer to the axle O, and the diameter of the wheel 20 decreases.

[0057] On the other hand, when the wheel 20 is rotated at the target speed, for example, when a control command to enlarge the diameter of the wheel 20 is input from the main control unit 33 to the diameter control unit 32, the diameter control unit 32 controls the diameter changing motor 11 so that the diameter of the wheel 20 becomes the target diameter related to the control command. Specifically, as shown in Fig. 10(b), the diameter control unit 32 controls the diameter changing motor 11 so that the rotation speed of the drive gear 23 is driven at the target speed C (a rotation speed slower than the rotation speed information of the wheel 20 from the speed control unit 31 by a specified speed) for a predetermined time (6 seconds in the example of Fig. 10(b)) according to the target diameter related to the control command.

[0058] As a result, the drive gear 23 is driven at a rotational speed relatively slower than the rotational speed of the wheel 20 (hub member 22) for a predetermined period of time, and as a result, the three idler gears 25A-25C meshed with the drive gear 23 rotate (spin) in the reverse direction around each gear shaft 25a. As a result, as shown in Fig. 1, the radially outer ends of each of the arm members 21A-21F rotate in a direction away from the axle O, and each of the ground contact arc members 26A-26F moves away from the axle O, and the diameter of the wheel 20 increases.

[0059] 10(a), when the diameter of the wheel 20 is changed while the rotation speed (rotation angular velocity) of the wheel 20 remains constant, the moving speed of the wheel drive device 1 changes according to the change in the diameter of the wheel 20. Specifically, when the diameter of the wheel 20 is reduced while the rotation speed (rotation angular velocity) of the wheel 20 remains constant, the moving speed of the wheel drive device 1 decreases, and when the diameter of the wheel 20 is enlarged, the moving speed of the wheel drive device 1 increases. Therefore, for example, when controlling the moving speed of the wheel drive device 1 to be kept constant even when the diameter of the wheel 20 is changed, the speed control unit 31 controls the wheel drive motor 12 to change the rotation speed (rotation angular velocity) of the wheel 20 according to the change in the diameter of the wheel 20.

[0060] [Modifications] Next, a modification of the wheel 20 in the above-described embodiment will be described. FIG. 11 is a front view of the wheel 20 according to this modified example with its diameter reduced.

[0061] When the wheel 20 is in use, a resistance (external force directed radially inward) from the road surface according to the weight of the wheel drive device 1 acts on the ground contact arc 26 of the wheel 20. Therefore, when the arm members 21A-21F are rotated to move the ground contact arc 26 away from the axle O while the wheel 20 is in use to enlarge the diameter of the wheel 20, it is necessary to rotate the arm members 21A-21F against the resistance from the road surface acting on the ground contact arc 26. Therefore, when the wheel diameter is enlarged while the wheel 20 is in use, the rotation load of the arm members 21A-21F is large, and the drive load of the diameter changing motor 11 that rotates and drives the drive gear 23 to rotate the arm members 21A-21F is large.

[0062] Therefore, in this modified example, as shown in FIG. 11, compression springs 29A to 29F are provided as spring force applying sections that apply a spring force in a direction such that the wheel radial position of each of the radially outer end sides (other end sides) of each arm member 21A to 21F moves radially outward to the wheel 20 in the above-described embodiment.

[0063] These compression springs 29A to 29F are provided in the slide slots 26b formed in the ground arc members 26A to 26F of the ground arc 26, and bias the mounting pin 21c inserted in the slide slots 26b in a direction in which the mounting pin 21c moves when the diameter is enlarged. As a result, a biasing force in a direction in which the mounting pin 21c moves when the diameter is enlarged is always applied to the mounting pin 21c attached to the end of the radially outer end side (other end side) of each arm member 21A to 21F. As a result, when the wheel diameter is enlarged against the resistance from the road surface acting on the ground arc 26, the arm members 21A to 21F can be rotated with the assistance of the biasing force of the compression springs 29A to 29F. Therefore, the driving load of the diameter changing motor 11 that rotates the drive gear 23 for rotating the arm members 21A to 21F can be reduced.

[0064] The biasing force of the compression springs 29A to 29F increases the drive load of the diameter changing motor 11 when the wheel diameter is reduced during use of the wheel 20. However, when the wheel diameter is reduced, the drive load of the diameter changing motor 11 is reduced by the resistance from the road surface acting on the ground contact arc 26, so the biasing force of the compression springs 29A to 29F does not pose a problem in terms of the drive load of the diameter changing motor 11.

[0065] Although an embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and various modifications and variations are possible within the scope of the spirit of the present invention described in the claims, unless otherwise specifically limited in the above description.

[0066] For example, in this embodiment, the wheel drive motor 12 that rotates the hub member 22 and the diameter changing motor 11 that rotates the drive gear 23 are arranged away from the axle O of the wheel 20 and transmit drive power via drive transmission belts 13, 14, but the wheel drive motor 12 and the diameter changing motor 11 may be arranged on the axle O of the wheel 20 and directly connected to the hub member 22 and the drive gear 23. As an example, Fig. 12 shows an example in which the wheel drive motor 12 and the diameter changing motor 11 are arranged on the axle O of the wheel 20 and directly connected to the hub member 22 and the drive gear 23, respectively.

[0067] In the above-described embodiment, the diameter control unit 32 controls the diameter changing motor 11 so that the drive gear 23 is rotated at the same rotational speed as the hub member 22 after the diameter of the wheel 20 reaches the target diameter, thereby driving the wheel 20 to rotate while maintaining the wheel 20 at the target diameter, but is not limited to this. For example, a switching mechanism may be provided that switches between a fixed state in which the hub member 22 and the drive gear 23 rotate integrally and an unfixed state in which the hub member 22 and the drive gear 23 are relatively rotatable, and the switching mechanism may be switched to the fixed state when the wheel 20 is driven to rotate while maintaining the wheel 20 at the target diameter.

[0068] As such a switching mechanism, for example, a locking mechanism can be used that can be switched between a locked state (fixed state) in which the arm gears 24A-24F and the idler gears 25A-25C, etc. are prohibited from rotating (spinning) around their respective gear shafts, and a state in which the lock is released (unfixed state).

[0069] By employing such a switching mechanism, when the wheel 20 is rotated while maintaining the target diameter, the wheel drive motor 12 and the diameter changing motor 11 are rotated together by switching to a fixed state, so that the entire wheel 20 can be rotated by the two motors 11, 12. As a result, the rotational drive force required for the wheel drive motor 12 can be further reduced. [Explanation of symbols]

[0070] 1: Wheel drive unit 10: Drive unit 11: Diameter changing motor 12: Wheel drive motor 13, 14: Drive transmission belt 15: Support frame 16,17: Motor pulley 20:Wheel 21A~21F: Arm parts 21a, 21b: Arm plate 21c: Mounting pin 22: Hub parts 22a, 22b: Hub plate 22c: opening 23: Drive gear 24: Diameter change mechanism 24A~24F: Arm gear 24a: Gear shaft 25A~25C: Idler gear 25a: Gear shaft 26: Ground arc 26A~26F: Ground arc member 26a: Fixing opening 26b: Slide slot 27: Diameter-changing drive pulley 28: Wheel drive pulley 29A~29F: Compression spring 30: Control device 31: Speed ​​control section 32: Diameter control section 33: Main control unit O: Axle

Claims

1. A hub member that rotates around the axis of the axle; a plurality of arm members each having one end connected to the hub member; a rotating member that is rotated coaxially with the axle by a driving force of an external driving source; a radius changing mechanism that changes the radial position of each of the other ends of the arm members by relative rotation of the rotating member with respect to the hub member; a wheel outer periphery member supported on the other end side of the plurality of arm members, the one end sides of the plurality of arm members are respectively connected to the hub member so as to be rotatable about arm axes parallel to the axle; The diameter changing mechanism changes the wheel radial position of each of the other ends of the multiple arm members by rotating the rotating member relative to the hub member so as to rotate each of the multiple arm members about the arm axis.

2. 2. The variable diameter wheel according to claim 1, A variable diameter wheel having a biasing force imparting portion that imparts a biasing force in a direction that causes each wheel radial direction position on the other end side of the multiple arm members to move radially outward in the wheel direction.

3. The variable diameter wheel according to claim 1 or 2, The wheel outer periphery member is configured such that a plurality of arc members each supported on the other end side of the plurality of arm members are arranged along the circumferential direction of the diameter variable wheel, and adjacent arc members are connected to each other so as to be able to move relatively in the circumferential direction of the diameter variable wheel, forming a circular ring shape.

4. The variable diameter wheel according to claim 1 or 2, The hub member is driven to rotate about the axis of the axle by a driving force from a second external driving source.

5. A variable diameter wheel according to claim 1 or 2; an external drive source provided outside the diameter variable wheel and configured to rotate the rotating member of the diameter variable wheel; a diameter control unit that controls the external drive source so that the diameter of the diameter variable wheel becomes a target diameter based on rotational speed information and target diameter information of the diameter variable wheel.

6. The variable diameter wheel according to claim 5 ; a first external drive source provided outside the diameter variable wheel and configured to rotate the rotating member of the diameter variable wheel; a second external drive source provided outside the variable diameter wheel and configured to rotate the hub member of the variable diameter wheel; a speed control unit that controls the second external drive source based on the target speed information so that the rotational speed of the variable-diameter wheel becomes the target speed; a diameter control unit that controls the external drive source so that the diameter of the diameter variable wheel becomes a target diameter based on rotational speed information and target diameter information of the diameter variable wheel.

7. 7. The wheel drive device according to claim 6, A wheel drive device characterized in that the diameter control unit controls the external drive source so that the rotating member is rotated at the same rotational speed as the rotational speed of the hub member after the diameter of the diameter-variable wheel becomes a target diameter.

8. 7. The wheel drive device according to claim 6, A wheel drive device having a switching mechanism that switches between a fixed state in which the hub member and the rotating member rotate integrally, and an unfixed state in which the hub member and the rotating member are relatively rotatable.

Images