Wheel driving device and wheel driving unit

Abstract

To provide a technique capable of driving wheels using a motor different from a first motor.SOLUTION: A wheel driving device for driving wheels traveling a facility installed under natural environment includes: a first motor 30; a first speed reducer 32 for reducing speed of output of the first motor 30, and outputting the output to wheels 20 from a first output shaft; and a second motor 38 which is provided on a second power transmission path 36 merged with a first power transmission path 34 to the first output shaft from the first motor 30.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a wheel drive device used for equipment installed in a natural environment.

Background Art

[0002] Patent Document 1 discloses a wheel drive device that drives wheels for running equipment installed in a natural environment. This wheel drive device includes a first motor and a first speed reducer that reduces the output of the first motor and outputs it to the wheels.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a wheel drive device that drives wheels for running equipment installed in a natural environment, there may be cases where it is advantageous to be able to drive the wheels using a motor different from the first motor.

[0005] Therefore, one object of the present disclosure is to provide a technique for enabling the wheels to be driven using a motor different from the first motor.

Means for Solving the Problems

[0006] A wheel drive device according to an aspect of the present disclosure is a wheel drive device that drives wheels for running equipment installed in a natural environment, and includes a first motor, a first speed reducer that reduces the output of the first motor and outputs it from a first output shaft to the wheels, and a second motor provided on a second power transmission path that merges into a first power transmission path from the first motor to the first output shaft.

Effects of the Invention

[0007] According to the present disclosure, in a wheel drive device that drives wheels for a facility installed in a natural environment, it becomes possible to drive the wheels using a motor different from the first motor.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments for implementing the wheel drive device of the present disclosure will be described. The same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted. In each drawing, for convenience of explanation, components are appropriately omitted, enlarged, or reduced. The drawings are to be viewed in accordance with the orientation of the reference numerals.

[0010] (First Embodiment) Refer to FIG. 1. The wheel drive device 10 is used for a facility 12 installed in a natural environment. Here, the natural environment means an environment that directly receives naturally generated wind. Places that satisfy such conditions include, for example, watersides such as harbors, coasts, lake shores, and river banks, as well as land. When installed on land, places that satisfy the condition of the natural environment include, for example, cargo gathering places such as freight stations, as well as construction sites. As the facility 12 installed in such a natural environment, here, a harbor crane installed in a harbor is exemplified. The specific example of this facility 12 is not particularly limited, and may be, for example, various cargo handling machines such as cranes and unloaders, or others.

[0011] Here, a gantry crane is shown as the port crane that serves as the facility 12, but the specific example is not particularly limited, and a ship crane or the like may also be used. This facility 12 includes a facility main body 14 and a lifting device 16 mounted on the facility main body 14 and used for cargo handling. The facility main body 14 includes a lower structure part 14a to which a plurality of wheels 20 are attached, and an upper structure part 14b supported by the lower structure part 14a and mounting the lifting device 16. The facility 12 travels along a rail 18 laid on the ground by a plurality of wheels 20.

[0012] By traveling by a plurality of wheels 20, the facility 12 can move between a working position for working using the facility 12 and a sheltered position where it has taken shelter from the working position. FIG. 1 shows a state where the facility 12 is at the working position. When at the working position, for example, cargo handling work using the facility 12 can be performed. The standby position is a position for reducing the wind load received by the facility 12 when it is at the working position, and is provided at a location away from the working position. Around the sheltered position, for example, a windbreak wall for reducing the wind load on the facility 12 arranged at the sheltered position may be installed.

[0013] The plurality of wheels 20 are used to run the facility 12. The wheel drive device 10 is used to drive at least some of the plurality of wheels 20. The wheels 20 driven by the wheel drive device 10 function as drive wheels. Here, an example is shown in which each of all the wheels 20 functions as a drive wheel driven by the wheel drive device 10, but a part of them may function as driven wheels not driven by the wheel drive device 10. Also, here, for convenience of explanation, the wheel drive device 10 is shown as being at a position away from the facility 12, but actually, each individual wheel drive device 10 is fixed to the facility main body 14 of the facility 12.

[0014] Refer to FIG. 2. The wheel drive device 10 includes a first motor 30, a first speed reducer 32 that reduces the output of the first motor 30 and outputs it from the first output shaft 32c to the wheel 20, and a second power transmission path 36 that merges into the first power transmission path 34 extending from the first motor shaft 30a of the first motor 30 to the first output shaft 32c. A second motor 38 provided thereon, and a second speed reducer 40 that reduces the output of the second motor 38. The wheel drive device 10 also includes a first brake 42 provided on the first power transmission path 34 and a second brake 44 provided on the second power transmission path 36.

[0015] The wheel drive device 10 includes the first power transmission path 34 and the second power transmission path 36 described above. The first power transmission path 34 is for transmitting rotation from the first motor 30 to the wheel 20 via the first output shaft 32c. The first power transmission path 34 includes a confluence rotating shaft 46 provided at the confluence point with the second power transmission path 36 and into which power is input from the second power transmission path 36. The second power transmission path 36 is for transmitting rotation from the second motor 38 at the confluence point with the first power transmission path 34. The rotation output from the second power transmission path 36 is output to the wheel 20 via the first power transmission path 34.

[0016] The first motor 30 is exemplified by a three-phase induction motor, but its specific example is not particularly limited, and it may be a single-phase induction motor, a synchronous motor, or the like. The first motor 30 includes a first motor shaft 30a that rotates by a first stator and a first rotor (not shown), and a first motor casing 30b that houses the first stator, the first rotor, and the first motor shaft 30a. The first motor casing 30b is supported by a first speed reducer casing 32d described later. To achieve this, in the present embodiment, the first motor casing 30b is fixed to the first speed reducer casing 32d, but the first motor casing 30b may be fixed to other members supported by the first speed reducer casing 32d.

[0017] The first speed reducer 32 includes a first input shaft 32a to which the output of the first motor 30 is input, a first speed reduction mechanism 32b that reduces the output of the first motor 30, a first output shaft 32c that outputs the rotation reduced by the first speed reduction mechanism 32b to the wheels 20, and a first speed reducer casing 32d that houses these components. In addition to this, the first speed reducer 32 of the present embodiment includes at least one first intermediate shaft 32e that forms part of a first power transmission path 34 extending from the first input shaft 32a to the first output shaft 32c.

[0018] The first input shaft 32a of the present embodiment is shown as an example that also serves as the first motor shaft 30a, but they may be separate. When they are separate, the first input shaft 32a and the first motor shaft 30a are connected directly or via other members so as to be integrally rotatable with each other. The first output shaft 32c outputs directly or indirectly from the first output shaft 32c to the wheels 20. In the present embodiment, there are a total of two first intermediate shafts 32e. In the present embodiment, the above-mentioned confluence portion rotation shaft 46 is constituted by the first intermediate shaft 32e on the front stage side.

[0019] Although not shown in the figure, the first speed reducer casing 32d is fixed to the equipment main body 14 of the equipment 12 via a torque arm 32f fixed to the first speed reducer casing 32d. The first speed reducer casing 32d rotatably supports each rotating shaft such as the first input shaft 32a via bearings (not shown).

[0020] The first speed reduction mechanism 32b of the present embodiment includes a front stage speed reduction portion 32ba provided on the front stage side of the first power transmission path 34 with respect to the confluence portion rotation shaft 46, and a rear stage speed reduction portion 32bb provided on the rear stage side of the first power transmission path 34 with respect to the confluence portion rotation shaft 46. In the present embodiment, the front stage speed reduction portion 32ba is constituted by a first orthogonal gear set 48, and the rear stage speed reduction portion 32bb is constituted by a two-stage parallel gear set 50. The orthogonal gear set refers to a gear set in which the rotation center lines thereof are orthogonal when viewed from a direction orthogonal to both the axial direction of the orthogonal pinion on the front stage side and the axial direction of the orthogonal gear on the rear stage side. The parallel gear set 50 refers to a gear set in which both the axial direction of the pinion on the front stage side and the axial direction of the gear on the rear stage side are parallel.

[0021] The first orthogonal gear set 48 consists of a first orthogonal pinion 48a on the front stage side and a first orthogonal gear 48b on the rear stage side that meshes with the first orthogonal pinion 48a. Here, the first orthogonal pinion 48a and the first orthogonal gear 48b are exemplified by a set of a bevel pinion and a bevel gear, but a set of a hypoid pinion and a hypoid gear or a set of a worm pinion and a worm gear may also be used. The first orthogonal pinion 48a is connected to the first input shaft 32a, and the first orthogonal gear 48b is connected to the confluence portion rotation shaft 46. The pinion of the front stage side parallel gear set 50 among the two-stage parallel gear sets 50 is connected to the confluence portion rotation shaft 46, and the gear that meshes with the pinion is connected to the first intermediate shaft 32e on the rear stage side. The pinion of the rear stage side parallel gear set 50 is connected to the first intermediate shaft 32e on the rear stage side, and the gear that meshes with the pinion is connected to the first output shaft 32c.

[0022] The second motor 38 is exemplified by a three-phase induction motor, but its specific example is not particularly limited, and it may be a single-phase induction motor, a synchronous motor, or the like. The second motor 38 includes a second motor shaft 38a that rotates by a second stator and a second rotor (not shown), and a second motor casing 38b that houses the second stator, the second rotor, and the second motor shaft 38a. The second motor casing 38b is supported by the first reduction gear casing 32d. To achieve this, in the present embodiment, the second motor casing 38b is fixed to a second reduction gear casing 40d as another member supported by the first reduction gear casing 32d, but it may be fixed to the first reduction gear casing 32d.

[0023] The second speed reducer 40 is provided on the second power transmission path 36. The second speed reducer 40 reduces the output of the second motor 38 and outputs it to the confluence portion rotating shaft 46 on the first power transmission path 34. The second speed reducer 40 includes a second input shaft 40a to which the output of the second motor 38 is input, a second speed reduction mechanism 40b that reduces the output of the second motor 38, a second output shaft 40c that outputs the rotation reduced by the second speed reduction mechanism 40b to the confluence portion rotating shaft 46, and a second speed reducer casing 40d that houses these. Here, an example is shown in which the second input shaft 40a also serves as the second motor shaft 38a, but these may be separate bodies. When these are separate bodies, the second input shaft 40a and the second motor shaft 38a are directly or via another member connected so as to be integrally rotatable with each other.

[0024] The second output shaft 40c of the present embodiment also serves as the confluence portion rotating shaft 46. In order to achieve this, the confluence portion rotating shaft 46 includes an extension portion 46a that extends outward from the first speed reducer casing 32d, and the extension portion 46a constitutes the second output shaft 40c. The confluence portion rotating shaft 46 and the second output shaft are configured by the same member. In addition to this, the second output shaft 40c and the confluence portion rotating shaft 46 may be separate bodies. When these are separate bodies, the second output shaft 40c and the confluence portion rotating shaft 46 are directly or via another member connected so as to be integrally rotatable with each other. In any case, the second output shaft 40c is provided so as to be integrally rotatable with the confluence portion rotating shaft 46 in the axial direction extension of the confluence portion rotating shaft 46.

[0025] In the present embodiment, the first power transmission path 34 is constituted by the first motor shaft 30a, the first input shaft 32a, the first speed reduction mechanism 32b, and the first output shaft 32c. This first power transmission path 34 is also constituted by the first intermediate shaft 32e when the first speed reducer 32 includes the first intermediate shaft 32e. This first power transmission path 34 includes the above-described confluence portion rotating shaft 46. In the present embodiment, the second power transmission path 36 is constituted by the second motor shaft 38a, the second input shaft 40a, the second speed reduction mechanism 40b, and the second output shaft 40c.

[0026] Here, the rated output (kW), rated torque (N·m), and rated rotation speed (min-1 ) is referred to as the first rated output Or1, the first rated torque Tr1, and the first rated rotational speed Nr1. The rated output (kW), rated torque (N·m), and rated rotational speed (min -1 ) of the second motor 38 are referred to as the second rated output Or2, the second rated torque Tr2, and the second rated rotational speed Nr2. The rated output refers to the rated value of the output that can be continuously output when at the rated voltage and rated frequency. The rated torque and rated rotational speed refer to the rated values of the torque and rotational speed when continuously outputting the rated output. Outputting the rated output is synonymous with outputting the rated torque at the rated rotational speed. The rated output is the product of the rated torque and the rated rotational speed. The rated outputs of the first and second motors 30 and 38 respectively are the outputs that can be output by the respective motors 30 and 38 under the same rated voltage and the same rated frequency.

[0027] In the first power transmission path 34, the reduction ratio of the portion on the front stage side of the confluence point with the second power transmission path 36 is referred to as the front stage first reduction ratio R1a. In the first power transmission path 34, the reduction ratio of the portion on the rear stage side of the confluence point with the second power transmission path 36 is referred to as the rear stage first reduction ratio R1b. The reduction ratio of the second speed reducer 40 is referred to as the second reduction ratio R2. The front stage first reduction ratio R1a becomes 1 when a part of the first speed reduction mechanism 32b is not present in the front stage side portion of the first power transmission path 34. The front stage first reduction ratio R1a, as in this embodiment, when there is a front stage reduction portion 32ba that is a part of the first speed reduction mechanism 32b in the front stage side portion of the first power transmission path 34, is the reduction ratio of the front stage reduction portion 32ba. The rear stage first reduction ratio R1b becomes the total reduction ratio of the first speed reducer 32 when the entire first speed reduction mechanism 32b is present in the rear stage side portion of the first power transmission path 34. The rear stage first reduction ratio R1b, as in this embodiment, when only a part of the first speed reduction mechanism 32b is present in the rear stage side portion of the first power transmission path 34, is the reduction ratio of the rear stage reduction portion 32bb. The second reduction ratio R2 refers to the total reduction ratio of the second speed reducer 40.

[0028] When the first motor 30 outputs the first rated output Or1, the torque and rotational speed acting on the confluence portion rotating shaft 46 are referred to as the first confluence portion torque Tt1 and the first confluence portion rotational speed Nc1. When the second motor 38 outputs the second rated output Or2, the torque and rotational speed acting on the confluence portion rotating shaft 46 are referred to as the second confluence portion torque Tt2 and the second confluence portion rotational speed Nc2.

[0029] When the first motor 30 outputs the first rated output Or1, the torque and its rotational speed output from the first output shaft 32c are referred to as the first output torque To1 and the first output rotational speed No1. When the second motor 38 outputs the second rated output Or2, the torque and its rotational speed output from the first output shaft 32c are referred to as the second output torque To2 and the second output rotational speed No2. Each output torque is used to drive the wheel 20.

[0030] At this time, in this embodiment, the first rated torque Tr1 of the first motor 30 is larger than the second rated torque Tr2 of the second motor 38. Also, the first rated rotational speed Nr1 of the first motor 30 is larger than the rated rotational speed Nr2 of the second motor 38. That is, Tr1 > Tr2 and Nr1 > Nr2. Also, in this embodiment, by satisfying the conditions regarding the reduction ratio described below, the second output torque To2 becomes larger than the first output torque To1. That is, To1 < To2. Also, in this embodiment, by satisfying the conditions regarding the reduction ratio described below, the first output rotational speed No1 becomes larger than the second output rotational speed No2. That is, No1 > No2. Note that the first rated output Or1 of the first motor 30 is larger than the second rated output Or2 of the second motor 38. That is, Or1 > Or2.

[0031] Under the condition of rated torque where Tr1 > Tr2, the concept for satisfying the condition of output torque where To1 < To2 will be described. When the first rated torque Tr1 is output from the first motor 30, the first confluence section torque Tt1 acting on the confluence section rotation shaft 46 is the product of the first rated torque Tr1 and the front-stage first reduction ratio R1a (= Tr1 × R1a). Also, when the second rated torque Tr2 is output from the second motor 38, the second confluence section torque Tt2 acting on the confluence section rotation shaft 46 is the product of the second rated torque Tr2 and the second reduction ratio R2 (= Tr2 × R2). Both the first and second confluence section torques Tt1 and Tt2 are amplified by the same amount by the rear-stage reduction section 32bb and then output as the first and second output torques To1 and To2. For this reason, the magnitude relationship between the first output torque To1 and the second output torque To2 is the same as the magnitude relationship between the first confluence section torque Tt1 and the second confluence section torque Tt2. When the second confluence section torque Tt2 is greater than the first confluence section torque Tt1, the second output torque To2 becomes greater than the first output torque To1. In other words, when the condition regarding the confluence section torque where Tt1 < Tt2 is satisfied, that is, when the following formula (1) is satisfied, the second output torque To2 becomes greater than the first output torque To1. Tr1 × R1a < Tr2 × R2 ··· Formula (1)

[0032] In this embodiment, under the condition regarding the rated torque where Tr1 > Tr2, the condition regarding the output torque where To1 < To2 is satisfied, that is, the first reduction ratio R1a and the second reduction ratio R2 of the previous stage are adjusted so as to satisfy Equation (1). In order to achieve this, the second reduction ratio R2 is made larger than the first reduction ratio R1a of the previous stage. That is, R1a < R2. For example, the first reduction ratio R1a of the previous stage is 50 and the second reduction ratio R2 is 100. At this time, as can be understood from Equation (1), the larger the second reduction ratio R2 is made with respect to the first reduction ratio R1a of the previous stage, the easier it is to satisfy the above-described condition regarding the output torque. That is, by making the second reduction ratio R2 larger than the first reduction ratio R1a of the previous stage, the higher the second reduction ratio R2 is set as the high reduction ratio, the easier it is to satisfy the condition regarding the output torque where To1 < To2 under the condition regarding the rated torque where Tr1 > Tr2. Note that when the condition regarding the output torque where To1 < To2 is satisfied under the condition regarding the rated torque where Tr1 > Tr2, it will inevitably satisfy the condition regarding the reduction ratio where R1a < R2.

[0033] Next, an idea for satisfying the condition regarding the output rotation speeds where No1 > No2 will be described. When the first rated rotation speed Nr1 is output from the first motor 30, the first confluence rotation speed Nc1 of the confluence rotation shaft 46 is the product of the first rated rotation speed Nr1 and the reciprocal of the front-stage first reduction ratio R1a (= Nr1 × (1 / R1a)). Also, when the second rated rotation speed Nr2 is output from the second motor 38, the second confluence rotation speed Nc2 of the confluence rotation shaft 46 is the product of the second rated rotation speed Nr2 and the reciprocal of the second reduction ratio R2 (= Nr2 × (1 / R2)). Both the first and second confluence rotation speeds Nc1 and Nc2 are decelerated by the same amount by the rear-stage reduction unit 32bb and then output as the first and second output rotation speeds No1 and No2. Therefore, the magnitude relationship between the first output rotation speed No1 and the second output rotation speed No2 is the same as the magnitude relationship between the first confluence rotation speed Nc1 and the second confluence rotation speed Nc2. When the first confluence rotation speed Nc1 is greater than the second confluence rotation speed Nc2, the first output rotation speed No1 becomes greater than the second output rotation speed No2. In other words, when the condition regarding the confluence rotation speed where Nc1 > Nc2 is satisfied, that is, when the following formula (2) is satisfied, the first output rotation speed No1 becomes greater than the second output rotation speed No2. Nr1×(1 / R1a)>Nr2×(1 / R2) ··· (2)

[0034] In the present embodiment, as described above, under the condition regarding the rated rotation speeds where Nr1 > Nr2, the condition regarding the reduction ratios where R1a < R2 is satisfied. Therefore, inevitably, the relationship of formula (2) is satisfied, and the condition regarding the output rotation speeds where No1 > No2 is satisfied.

[0035] As described above, when the first rated output Or1 is output from the first motor 30, a first output rotation speed No1 greater than the second output rotation speed No2 and a first output torque To1 smaller than the second output torque To2 are output. Also, when the second rated output Or2 is output from the second motor 38, a second output rotation speed No2 smaller than the first output rotation speed No2 and a second output torque To2 greater than the first output torque To1 are output.

[0036] The effects of the above-described wheel drive device 10 will be described.

[0037] (A) The wheel drive device 10 includes a second motor 38 provided on a second power transmission path 36 that merges into the first power transmission path 34. Thereby, in the wheel drive device 10 that drives the wheel 20 for running equipment installed in a natural environment, the wheel 20 can be driven using a second motor 38 different from the first motor 30.

[0038] (B) The wheel drive device 10 includes a second speed reducer 40 provided on the second power transmission path 36. Thereby, by adjusting the second reduction ratio R2 of the second speed reducer 40, the second output torque To2 output from the first output shaft 32c by the output of the second motor 38 can be easily adjusted without adjusting the first output torque To1 output from the first output shaft 32c by the output of the first motor 30.

[0039] (C) When the second motor 38 outputs the second rated output Or2, the second output torque To2 output from the first output shaft 32c is larger than the first output torque To1 output from the first output shaft 32c when the first motor 30 outputs the first rated output Or1. Thereby, the output torque output from the first output shaft 32c when driving the wheel 20 using only the second motor 38 can be increased compared to the case of driving the wheel 20 using only the first motor 30. As a result, the output torque output from the first output shaft 32c can be increased without increasing the capacity of the first motor 30.

[0040] (D) The second rated torque Tr2 of the second motor 38 is smaller than the first rated torque Tr1 of the first motor 30. Thereby, it is possible to reduce the size of the capacity of the second motor 38 compared to the first motor 30 while satisfying the condition of the first output torque To1 < the second output torque To2. Therefore, it is advantageous for cost reduction of the wheel drive device 10 compared to the case of using a second motor 38 having a larger capacity than the first motor 30.

[0041] Generally, in order to increase the output torque, it is more cost-effective to combine a small-capacity motor and a speed reducer with a high reduction ratio than to simply increase the capacity of the motor alone. According to this embodiment, by using the second motor 38 with a smaller capacity than the first motor 30 and the second speed reducer 40 with a high reduction ratio, it is more advantageous for cost reduction of the wheel drive device 10 compared to the case of increasing the capacity of the first motor 30 so as to output the second output torque To2.

[0042] In particular, since the facility 12 is installed in a natural environment, when the facility 12 is made to travel in an environment where a typhoon with a high maximum wind speed occurs, a very large wind load acts on the facility 12. In order to make the facility 12 travel against this large wind load acting on the facility 12, an increase in the output torque output from the first output shaft 32c is required. According to this embodiment, it is effective in that, without increasing the capacity of the first motor 30, it is possible to realize such an increase in output torque while making cost reduction advantageous by using the small-capacity second motor 38.

[0043] (E) The first output rotation speed No1 of the first output torque To1 output from the first output shaft 32c when the first motor 30 outputs the rated output Or1 is greater than the second output rotation speed No2 of the second output torque To2 output from the first output shaft 32c when the second motor 38 outputs the second rated output Or2. That is, when the first motor 30 outputs the rated output Or1, an output torque with a high rotational speed and a low torque is output from the first output shaft 32c, and when the second motor 38 outputs the second rated output Or2, an output torque with a low rotational speed and a high torque is output from the first output shaft 32c. Thereby, when a large output torque is not required, the first motor 30 outputs an output torque with a high rotational speed from the first output shaft 32c, and thereby drives the wheels 20, so that the facility 12 can travel at a high speed. On the other hand, when a large output torque is required, the second motor 38 can drive the wheels 20 with the high-torque output torque output from the first output shaft 32c.

[0044] Here, the case of "requiring a large torque" means, for example, the case of driving the facility 12 to the evacuation position under a situation where the wind load acting on the facility 12 is extremely large. Here, the case of "not requiring a large output torque" means, for example, the case of driving the facility 12 at the working position when the wind load acting on the facility is not large. In particular, when driving the facility 12 to the evacuation position under a situation where the wind load acting on the facility 12 is extremely large, it is only necessary to drive the facility 12 to the evacuation position. Therefore, unlike the case of driving the facility 12 at the working position in order to work using the facility 12, high speed is not required for the driving of the facility 12. That is, in this situation, a high torque output torque is required, but the high rotational speed as in the case of working using the facility 12 is not required. Therefore, in such a situation, even if the second motor 38 outputs an output torque with a low rotational speed in order to output a high torque output torque, there is no problem. For this reason, when installed in the natural environment, this configuration is particularly effective for use in such a situation.

[0045] Next, other features of the wheel drive device 10 will be described. The traveling direction of the wheel 20 is defined as the wheel traveling direction X (the depth direction of the paper surface in FIG. 2), the axial direction of the first output shaft 32c is defined as the output shaft direction Y, and the direction orthogonal to the traveling direction X and the output shaft direction Y is defined as the height direction Z. In the present embodiment, the wheel traveling direction X and the output shaft direction Y are in the horizontal direction, and the height direction Z is in the vertical direction. In this specification, "parallel" and "orthogonal" include substantially parallel and substantially orthogonal in addition to geometrically strict parallel and orthogonal.

[0046] The wheel 20 is provided on a portion of the first output shaft 32c that protrudes from one side in the output shaft direction Y (the right side of the paper surface in FIG. 2) of the first reduction gear casing 32d. The second reduction gear 40 is disposed on one side in the output shaft direction Y with respect to the first reduction gear 32. The second reduction gear 40 is not disposed in the wheel traveling direction X with respect to the first reduction gear 32, nor is it disposed on the other side in the output shaft direction Y with respect to the first reduction gear 32.

[0047] (F) As a result, compared with the case where the second speed reducer 40 is arranged in the wheel traveling direction X with respect to the first speed reducer 32, it becomes easier to avoid interference with other wheel drive devices 10 adjacent in the wheel traveling direction X. Also, compared with the case where the second speed reducer 40 is arranged on the other side (the left side of the paper surface in FIG. 2) in the output shaft direction Y with respect to the first speed reducer 32, it is advantageous for miniaturization in the output shaft direction Y of the wheel drive device 10.

[0048] The first motor 30 is arranged in the height direction Z (here, the upper side in the vertical direction) with respect to the first speed reducer 32. The first motor 30 is not arranged in the wheel traveling direction X with respect to the first speed reducer 32, nor is it arranged in the output shaft direction Y with respect to the first speed reducer 32.

[0049] (G) As a result, compared with the case where the first motor 30 is arranged in the wheel traveling direction X with respect to the first speed reducer 32, it becomes easier to avoid interference with other wheel drive devices 10 adjacent in the wheel traveling direction X. Also, compared with the case where the first motor 30 is arranged on the other side in the output shaft direction Y with respect to the first speed reducer 32, it is advantageous for miniaturization in the output shaft direction Y of the wheel drive device 10.

[0050] The first motor shaft 30a of the first motor 30 is parallel to the height direction Z, and the second output shaft 40c of the second speed reducer 40 is parallel to the output shaft direction Y. The first motor shaft 30a and the second output shaft 40c are provided so that their axial directions are orthogonal to each other. Rotation is input to the first speed reducer 32 from the first motor shaft 30a and the second output shaft 40c whose axial directions are orthogonal to each other in this way. To achieve this, the first speed reducer 32 includes a first orthogonal gear set 48 provided on the first power transmission path 34, and a confluence section rotating shaft 46 that is parallel to the output shaft direction Y and is provided so as to be rotatable integrally with the second output shaft 40c. The first orthogonal gear set 48 includes a first orthogonal pinion 48a parallel to the height direction Z and a first orthogonal gear 48b parallel to the output shaft direction Y. The confluence section rotating shaft 46 may be provided so as to be rotatable integrally with the first orthogonal gear 48b, or may be provided on the subsequent stage side of a rotating shaft that is rotatable integrally with the first orthogonal gear 48b. For example, the confluence section rotating shaft 46 may be constituted by the subsequent stage side first intermediate shaft 32e among a total of two first intermediate shafts 32e. The second output shaft 40c is provided on the axial extension of the confluence section rotating shaft 46.

[0051] The second motor 38 is arranged in the height direction Z with respect to the second speed reducer 40. The direction of the first motor 30 in the height direction Z with respect to the first speed reducer 32 is vertically upward, and the direction of the second motor 38 in the height direction Z with respect to the second speed reducer 40 is also vertically upward. That is, the direction of the first motor 30 in the height direction Z with respect to the first speed reducer 32 and the direction of the second motor 38 in the height direction Z with respect to the second speed reducer 40 are aligned.

[0052] (H) By arranging the second motor 38 in the height direction Z with respect to the second speed reducer 40 in this way, compared with the case where the second motor 38 is arranged in the wheel traveling direction X with respect to the second speed reducer 40, it becomes easier to avoid interference with other wheel drive devices 10 adjacent in the wheel traveling direction X. Also, compared with the case where the second motor 38 is arranged in the output shaft direction Y with respect to the second speed reducer 40, it is advantageous for miniaturization in the output shaft direction Y of the wheel drive device 10. Further, by aligning the direction of the first motor 30 with respect to the first speed reducer 32 and the direction of the second motor 38 with respect to the second speed reducer 40, it is advantageous for miniaturization in the height direction Z of the wheel drive device 10.

[0053] When arranging the second motor 38 and the second speed reducer 40 in such a layout, it is necessary to make the axial direction of the second input shaft 40a of the second speed reducer 40 orthogonal to the axial direction of the second output shaft 40c of the second speed reducer 40. To achieve this, the second speed reducer 40 includes the aforementioned second orthogonal gear set 52 provided on the second power transmission path 36. The second orthogonal gear set 52 of the present embodiment includes a front-stage second orthogonal pinion 52a connected to the second input shaft 40a and a rear-stage second orthogonal gear 52b connected to the second output shaft 40c.

[0054] Next, a wheel drive unit 60 using the wheel drive device 10 will be described. Refer to FIGS. 1 and 2. The wheel drive unit 60 includes a control device 62 that controls the operation of the wheel drive device 10. The control device 62 is realized by a combination of hardware elements and software elements, or only by hardware elements. As the hardware elements, a processor, ROM (Read Only Memory), and RAM (Random Access Memory) are used. As the software elements, programs such as an operating system and an application are used.

[0055] The control device 62 incorporates a first motor drive circuit for driving the first motor 30 and a second motor drive circuit for driving the second motor 38. The motor drive circuit is, for example, an inverter, but it may also be a servo amplifier or the like. The motor drive circuit converts the power supplied from an external power source into drive power and drives the motors 30 and 38 by supplying the drive power to the motors 30 and 38. The motors 30 and 38 are driven in response to the drive power supplied from the motor drive circuit of the control device 62, whereby the operation of the wheel drive device 10 is controlled. At this time, the control device 62 supplies, for example, drive power for setting the motors 30 and 38 to a target rotational speed to the motors 30 and 38, whereby the motors 30 and 38 are driven to reach the target rotational speed.

[0056] The control device 62 is capable of executing a normal mode as a first mode in which the wheels 20 are driven by the first motor 30 and a retraction mode as a second mode in which the wheels 20 are driven by at least the second motor 38. The normal mode is used when the facility 12 is run at the work position. The retraction mode is used when the facility 12 is retracted from the work position to the retraction position. The control device 62 is capable of executing either the normal mode or the retraction mode according to a command sent from a command device (not shown). The command device can send a command for specifying the mode to be executed by the control device 62 according to an input operation by the user. The command device is constituted by, for example, a control panel provided on the facility 12, as well as an information processing terminal such as a smartphone or a tablet.

[0057] When the normal mode is executed, the control device 62 drives the first motor 30 by the first motor drive circuit and does not drive the second motor 38 by the second motor drive circuit. In this case, the control device 62 may drive the first motor 30 so that, for example, the first motor 30 reaches the first rated rotation speed Nr1. When the retraction mode is executed, the control device 62 drives at least the second motor 38 by the second motor drive circuit. In this case, the control device 62 may drive the second motor 38 so that, for example, the second motor 38 reaches the second rated rotation speed Nr2. When the control device 62 of the present embodiment executes the retraction mode, the control device 62 drives the wheels 20 by both the first motor 30 and the second motor 38. Therefore, in this case, the control device 62 drives the first motor 30 by the first motor drive circuit and drives the second motor 38 by the second motor drive circuit.

[0058] When the control device 62 drives both the first motor 30 and the second motor 38, the control device 62 rotates the first motor 30 at a rotation speed corresponding to the rotation speed of the second motor 38. Specifically, let the rotation speed of the second motor 38 be the motor rotation speed Ni2, and let the rotation speed of the confluence shaft 46 when the second motor 38 is rotated at the motor rotation speed Ni2 be the confluence rotation speed Nc2'. The confluence rotation speed Nc2' is the magnitude obtained by multiplying the motor rotation speed Ni2 by the reciprocal of the second reduction ratio R2 (= Ni2 × (1 / R2)). When the rotation speed of the first motor 30 is the motor rotation speed Ni1, let the rotation speed of the confluence shaft 46 when the first motor 30 is rotated at the motor rotation speed Ni1 be the confluence rotation speed Nc1'. The confluence rotation speed Nc1' is the magnitude obtained by multiplying the motor rotation speed Ni1 by the reciprocal of the first reduction ratio R1a in the previous stage (= Ni1 × (1 / R1a)). At this time, the first motor 30 is rotated at the motor rotation speed Ni1 such that the confluence rotation speed Nc1' of the confluence shaft 46 due to the output of the first motor 30 matches the confluence rotation speed Nc2' of the confluence shaft 46 due to the output of the second motor 38. Actually, the first motor 30 is rotated at the motor rotation speed Ni1 corresponding to the motor rotation speed Ni2 of the second motor 38 so as to satisfy the following formula (3). Ni1 = Ni2 × (R1a / R2) ··· (3)

[0059] At this time, for example, the control device 62 reads out the first reduction ratio R1a and the second reduction ratio R2 previously stored in the storage unit, and sets the motor rotation speed Ni2 of the second motor 38 for driving the wheels 20. The motor rotation speed Ni2 set for the second motor 38 is, for example, the aforementioned second rated rotation speed Nr2. After that, the control device 62 derives the motor rotation speed Ni1 of the first motor 30 from Equation (3) based on the read reduction ratios R1a, R2 and the set motor rotation speed Ni2, and may drive the first motor 30 so as to obtain the motor rotation speed Ni1.

[0060] (I) As described above, the control device 62 can execute an avoidance mode in which the wheels 20 are driven by both the first motor 30 and the second motor 38. As a result, at the merging section rotating shaft 46, the torque transmitted by the output of the second motor 38 and the torque transmitted by the output of the first motor 30 are combined, and the combined torque is amplified in the rear-stage reduction section 32bb and then output from the wheels 20. Thus, in the avoidance mode, by driving the wheels 20 with the first motor 30 and the second motor 38, the output torque output from the first output shaft 32c to the wheels 20 can be increased as compared with the case where the wheels 20 are driven only by the second motor 38.

[0061] When executing the avoidance mode, the control device 62 may drive the wheels 20 only by the second motor 38.

[0062] Referring to FIG. 2, the first and second brakes 42 and 44 will be described next. The first brake 42 of the present embodiment is a friction brake, but is not limited thereto, and may be configured by various brakes including an electric brake such as a regenerative brake. The first brake 42 of the present embodiment is used as a part of the brake-equipped motor associated with the first motor 30. The first brake 42 can apply a first braking torque to the first power transmission path 34. The first brake 42 of the present embodiment applies a first braking torque to the first motor shaft 30a on the first power transmission path 34.

[0063] The second brake 44 of this embodiment is a friction brake, but is not limited thereto, and may be constituted by various brakes including an electric brake such as a regenerative brake. The second brake 44 of this embodiment is used as a part of a motor with a brake associated with the second motor 38. The second brake 44 can apply a second braking torque to the second power transmission path 36. The second brake 44 of this embodiment applies a second braking torque to the second motor shaft 38a on the second power transmission path 36.

[0064] The first brake 42 can switch between a braking state in which a first braking torque is applied to the first motor shaft 30a and a braking release state in which the application of the first braking torque is released. The second brake 44 can switch between a braking state in which a second braking torque is applied to the second motor shaft 38a and a braking release state in which the application of the second braking torque is released. Each of the brakes 42 and 44 of this embodiment is a non-excitation operation type brake, which becomes a braking state when not energized and becomes a braking release state when energized. In addition to this, the brakes 42 and 44 may be excitation operation type brakes that become a braking state when energized.

[0065] The control device 62 of this embodiment can control the operations of the brakes 42 and 44 by controlling the presence or absence of energization to the first brake 42 and the second brake 44. The control device 62 can switch the first brake 42 between a braking state and a braking release state by controlling the presence or absence of energization to the first brake 42. Further, the control device 62 can switch the second brake 44 between a braking state and a braking release state by controlling the presence or absence of energization to the second brake 44.

[0066] While the control device 62 drives the wheels 20 by the first motor 30 or the second motor 38 in the normal mode or the avoidance mode, the control device 62 switches the first brake 42 and the second brake 44 to the brake release state so that no braking torque is applied by each of the brakes 42 and 44. After the driving of the first motor 30 or the second motor by the normal mode or the avoidance mode is completed, the control device 62 switches at least one of the first brake 42 and the second brake 44 from the brake release state to the braking state. In the present embodiment, both the first and second brakes 42 and 44 are switched from the brake release state to the braking state. Thereby, compared with the case where only one of the first and second brakes 42 and 44 is switched to the braking state, the braking torque output from the first output shaft 32c to the wheels 20 can be increased.

[0067] In order to maintain the facility 12 in a stopped state against a large wind load, it is necessary to output a large braking torque. Since a large braking torque can be output using both the first and second brakes 42 and 44, it is also advantageous in that it is not necessary to increase the size of the first brake 42 in order to output a large braking torque. In particular, when the first brake 42 forms part of a motor with a brake, increasing the size of the first brake 42 will inevitably increase the capacity of the first motor 30 accordingly. In this regard, it is advantageous in that it is not necessary to increase the capacity of the first motor 30 by avoiding an increase in the size of the first brake 42.

[0068] In the present embodiment, when switching both the first and second brakes 42 and 44 to the braking state, one of the brakes is first switched to the braking state, and then the other brake is switched to the braking state. Thereby, compared with the case where both the brakes 42 and 44 are simultaneously switched to the braking state, the braking torque output from the first output shaft 32c to the wheels 20 during the running of the facility 12 can be increased step by step, and it becomes easier to stably stop the facility 12 during the running of the facility 12. In addition to this, both the first and second brakes 42 and 44 may be simultaneously switched from the brake release state to the braking state.

[0069] (Second Embodiment) Refer to FIG. 3. In the following embodiments, among the components described in the first embodiment, the components not described below may have the same content as that of the first embodiment applied thereto.

[0070] The wheel drive device 10 of the present embodiment includes a clutch 70 provided on the second power transmission path 36. The clutch 70 is provided on the second power transmission path 36 on the downstream side of the second stator and the second rotor (not shown) of the second motor 38. The clutch 70 of the present embodiment is provided on the second output shaft 40c on the downstream side of the second reduction mechanism 40b of the second speed reducer 40 in the second power transmission path 36. Here, the downstream side refers to the side of the confluence portion rotation shaft 46 in the second power transmission path 36.

[0071] The clutch 70 can switch between a power transmission state that permits the transmission of power passing through itself on the second power transmission path 36 and a power cutoff state that cuts off the power attempting to pass through itself. The clutch 70 can switch between the power transmission state and the power cutoff state according to the control by the control device 62. When in the normal mode, the control device 62 sets the clutch 70 to the power cutoff state. Thereby, while the wheels 20 are being driven by the output of the first motor 30, it is possible to avoid a situation where rotation is transmitted from the first power transmission path 34 to the second motor shaft 38a side of the second power transmission path 36. Further, when in the standby mode, the control device 62 sets the clutch 70 to the power transmission state. Thereby, the output of the second motor 38 can be transmitted to the first power transmission path 34, and the wheels 20 can be driven by that output.

[0072] As described above, by providing the clutch 70 on the second power transmission path 36, when driving the wheels by the output of the first motor 30, by switching the clutch 70 to the power-off state, it is not necessary to rotate the second motor shaft 38a of the second motor 38. As a result, when the second motor 38 is not being driven, it is possible to avoid a situation where unnecessary operating noise and heat are generated in the second motor 38 due to the rotation of the second motor shaft 38a of the second motor 38. In particular, when the second speed reducer 40 is provided on the second power transmission path 36, when driving the wheels 20 by the output of the first motor 30, the rotation of the confluence rotation shaft 46 on the first power transmission path 34 is increased in speed by the second speed reducer 40. As a result, the second motor shaft 38a rotates at high speed, and there is a problem that the above-mentioned unnecessary operating noise and heat are greatly affected. According to the present embodiment, there is an advantage that this problem can be advantageously solved.

[0073] In addition to this, the wheel drive device 10 of the present embodiment can also obtain the same effects as (A) to (I) described above in the first embodiment.

[0074] (Third Embodiment) Refer to FIG. 4. In the first embodiment, an example was described in which the first motor shaft 30a of the first motor 30 also serves as the first input shaft 32a of the first speed reducer 32, and a confluence rotation shaft 46 is provided separately from the first input shaft 32a. In addition to this, the first motor shaft 30a of the first motor 30 may also serve as the first input shaft 32a of the first speed reducer 32, and the first input shaft 32a may constitute the confluence rotation shaft 46. In this case, the first motor 30 is not arranged in a direction (vertical direction on the paper surface) orthogonal to the output shaft direction Y with respect to the first speed reducer 32, but is arranged in the output shaft direction Y with respect to the first speed reducer 32. The first speed reduction mechanism 32b of the present embodiment does not have a front-stage speed reduction portion 32ba provided on the front-stage side of the confluence rotation shaft 46, and only the rear-stage speed reduction portion 32bb remains. In this case, the above-mentioned front-stage first speed reduction ratio R1a becomes 1. The wheel drive device 10 of the present embodiment can also obtain the same effects as (A) to (E), (I) described above in the first embodiment.

[0075] (Fourth Embodiment) Refer to FIG. 5. In the first embodiment, an example where the second speed reducer 40 is not provided on the first power transmission path 34 was described. Instead, the second speed reducer 40 may be provided on the first power transmission path 34. In this embodiment, the second output shaft 40c of the second speed reducer 40 is provided so as to be integrally rotatable with the first motor shaft 30a of the first motor 30 and is also provided so as to be integrally rotatable with the first input shaft 32a of the first speed reducer 32. The first power transmission path 34 of this embodiment is composed of the first motor shaft 30a, the second output shaft 40c, the first input shaft 32a, the first speed reduction mechanism 32b, and the first output shaft 32c. Also, the second power transmission path 36 of this embodiment is composed of the second motor shaft 38a, the second input shaft 40a, and the second speed reduction mechanism 40b. In this case, the confluence portion rotation shaft 46 is constituted by the second output shaft 40c.

[0076] The second speed reducer 40 is disposed between the first motor 30 and the first speed reducer 32, and the second motor 38 is disposed in the height direction Z with respect to the second speed reducer 40. Similar to the third embodiment, the first speed reduction mechanism 32b of this embodiment does not have a front-stage speed reduction portion 32ba provided on the front stage side of the confluence portion rotation shaft 46, and only the rear-stage speed reduction portion 32bb remains. The first orthogonal gear set 48 that constituted the front-stage speed reduction portion 32ba in the first embodiment becomes a part of the rear-stage speed reduction portion 32bb. Also with the wheel drive device 10 of this embodiment, the same effects as (A) to (E) and (I) described above in the first embodiment can be obtained.

[0077] (Fifth Embodiment) Refer to FIG. 6. FIG. 6 is a diagram schematically showing the wheels 20 and the wheel drive devices 10A, 10B used in the facility 12. Here, an example where there are a total of eight wheels 20 and a total of eight wheel drive devices 10A, 10B is shown. Note that the total number of wheels 20 and wheel drive devices 10A, 10B used in the facility 12 is not particularly limited.

[0078] The wheel drive unit 60 includes a plurality of wheel drive devices 10A, 10B. Each of the plurality of wheel drive devices 10A, 10B is for driving an individual wheel 20 used in the facility 12. The plurality of wheel drive devices 10A, 10B includes a first wheel drive device 10A and a second wheel drive device 10B.

[0079] The first wheel drive device 10A is the wheel drive device described in the first embodiment and the like, and includes a second motor 38 and a second speed reducer 40 in addition to the first motor 30 and the first speed reducer 32. Further, the first wheel drive device 10A also includes a first brake 42 and a second brake 44 having an arbitrary configuration.

[0080] The second wheel drive device 10B includes a third motor 80 that drives the wheel 20. As an arbitrary configuration, the second wheel drive device 10B includes, in addition to the third motor 80, a third speed reducer 82 that reduces the output of the third motor 80 and outputs it to the wheel 20. In addition, as an arbitrary configuration, the second wheel drive device 10B includes a third brake 84 that is provided in the power transmission path from the motor shaft (not shown) of the third motor 80 to the wheel 20 and applies a braking torque to the power transmission path. In the present embodiment, the third motor 80, the third speed reducer 82, and the third brake 84 are the first motor 30, the first speed reducer 32, and the first brake 42 described above, but may be motors, speed reducers, and brakes different from these. The second wheel drive device 10B drives the wheel 20 by only one third motor 80 and does not include other motors for driving the wheel 20.

[0081] The wheel drive unit 60 may have at least one of all the wheel drive devices 10A and 10B as the first wheel drive device 10A and the rest as the second wheel drive device 10B. In the present embodiment, half of all the wheel drive devices 10 are the first wheel drive device 10A. Specifically, out of a total of eight wheel drive devices 10A and 10B, a total of four, which is half, are the first wheel drive device 10A, and the remaining total of four are the second wheel drive device 10B. In addition, only one of all the wheel drive devices 10A and 10B may be the first wheel drive device 10A and the rest may be the second wheel drive device 10B. In any case, the number of the first wheel drive devices 10A among all the wheel drive devices 10A and 10B is not particularly limited.

[0082] The first wheel drive device 10A has a larger number of motors than the second wheel drive device 10B, and accordingly, it is more costly. In the present embodiment, by making a part of all the wheel drive devices 10 into the first wheel drive device 10A, an increase in cost can be suppressed as compared with the case where all of them are made into the first wheel drive device 10A.

[0083] Note that in the wheel drive unit 60, all of the wheel drive devices 10A and 10B may be the first wheel drive device 10A.

[0084] Next, modified forms of each of the components described so far will be described.

[0085] The first power transmission path 34 extends from the first motor 30 to the first output shaft 32c of the first speed reducer 32, and specific examples of the members constituting the intermediate portion thereof are not particularly limited. The second power transmission path 36 extends from the second motor 38 to the confluence portion rotation shaft 46, and specific examples of the members constituting the intermediate portion thereof are not particularly limited.

[0086] The number of gear sets included in the first and second speed reduction mechanisms 32b and 40b is not particularly limited, the type of gear set is not limited, and it does not have to include an orthogonal gear set. The type of gear set used in each of the speed reduction mechanisms 32b and 40b is not particularly limited, and various gear sets such as an orthogonal gear set, a parallel gear set, and a coaxial gear set (a gear set of a simple planetary type speed reducer, a gear set of an eccentric swing type speed reducer, a gear set of a flexure engagement type speed reducer) may be used.

[0087] It is sufficient that the second motor 38 is provided on the second power transmission path 36 in the wheel drive device 10, and the second speed reducer 40 and the second brake 44 are not essential. A clutch 70 does not have to be provided on the second power transmission path 36.

[0088] The arrangement position of the second speed reducer 40 with respect to the first speed reducer 32 is not particularly limited. For example, the second speed reducer 40 may be arranged on the other side of the first speed reducer 32 in the wheel traveling direction X or the output shaft direction Y. When the second speed reducer 40 is arranged in the output shaft direction Y with respect to the first speed reducer 32, the second speed reducer 40 may include a coaxial gear set or the like without including an orthogonal gear set. Also, the arrangement position of the first motor 30 with respect to the first speed reducer 32 is not particularly limited. For example, the first motor 30 may be arranged in the wheel traveling direction X or the output shaft direction Y with respect to the first speed reducer 32. When the first motor 30 is arranged in the output shaft direction Y with respect to the first speed reducer 32, the first speed reducer 32 may include only a parallel gear set without including an orthogonal gear set.

[0089] The second motor 38 may be arranged in either the wheel traveling direction X or the output shaft direction Y with respect to the second speed reducer 40. Also, the orientation of the first motor 30 in the height direction Z with respect to the first speed reducer 32 and the orientation of the second motor 38 in the height direction Z with respect to the second speed reducer 40 may be different.

[0090] On the condition that the first output torque To1 < the second output torque To2, the first rated torque Tr1 of the first motor 30 < the second rated torque Tr2 of the second motor 38 may be set.

[0091] From the viewpoint of increasing the output torque output from the first output shaft 32c to the wheels 20 compared to the case where the wheels 20 are driven only by the first motor 30, the case where the second speed reducer 40 is provided on the second power transmission path 36 and the second output torque To2 is made larger than the first output torque To1 has been described. From a similar viewpoint, the control device 62 may be capable of executing only the mode (the retracted mode in the embodiment) in which the wheels 20 are driven by the first motor 30 and the second motor 38.

[0092] The above embodiments and modified forms are examples. The technical ideas abstracted from these should not be construed as being limited to the contents of the embodiments and modified forms. Many design changes such as component changes, additions, deletions, etc. are possible for the contents of the embodiments and modified forms. In the foregoing embodiments, with respect to the contents for which such design changes are possible, the notation "embodiment" is attached and emphasized. Also, a substitution of any of the components and expressions of the present disclosure with each other among a method, apparatus, system, etc. is also valid as an aspect of the present disclosure.

Explanation of Signs

[0093] 10... Wheel drive device, 10A... First wheel drive device, 10B... Second wheel drive device, 12... Equipment, 20... Wheel, 30... First motor, 32... First speed reducer, 32c... First output shaft, 34... First power transmission path, 36... Second power transmission path, 38... Second motor, 40... Second speed reducer, 40c... Second output shaft, 48a... First orthogonal pinion, 48b... First orthogonal gear, 60... Wheel drive unit, 62... Control device, 70... Clutch.

Claims

1. A wheel drive device for driving wheels that run equipment installed in a natural environment, comprising: a first motor; a first speed reducer that reduces the output of the first motor and outputs it to the wheels from a first output shaft; a second motor provided on a second power transmission path that merges with a first power transmission path from the first motor to the first output shaft.

2. The wheel drive device according to claim 1, further comprising a second speed reducer provided on the second power transmission path for reducing the output of the second motor.

3. When the rated output of the first motor is output from the first motor, a first output torque is output from the first output shaft. When the rated output of the second motor is output from the second motor, a second output torque is output from the first output shaft. The wheel drive device according to claim 2, wherein the second output torque is greater than the first output torque.

4. The wheel drive device according to claim 3, wherein the rated torque of the second motor is smaller than the rated torque of the first motor.

5. When the rated output of the first motor is output from the first motor, a first output torque of a first output rotational speed is output from the first output shaft. When the rated output of the second motor is output from the second motor, a second output torque of a second output rotational speed is output from the first output shaft. The wheel drive device according to claim 3, wherein the first output rotational speed is greater than the second output rotational speed.

6. A wheel is provided on the first output shaft at a portion protruding from a speed reducer casing of the first speed reducer to one side in the axial direction of the first output shaft. The wheel drive device according to claim 2, wherein the second speed reducer is arranged on one side in the axial direction with respect to the first speed reducer.

7. The wheel drive device according to claim 6, wherein the first motor is arranged in a height direction perpendicular to the traveling direction of the wheel and the axial direction with respect to the first speed reducer.

8. The wheel drive device according to claim 7, wherein the second motor is arranged in the height direction with respect to the second speed reducer.

9. The wheel drive device according to claim 1, further comprising a clutch provided on the second power transmission path.

10. A wheel drive device according to any one of claims 1 to 8, and a control device for controlling the operation of the wheel drive device. The control device is a wheel drive unit capable of executing a first mode in which the wheels are driven by the first motor and a second mode in which the wheels are driven by the first motor and the second motor.

11. A wheel drive unit comprising a plurality of wheel drive devices for driving a plurality of wheels that run equipment installed in a natural environment, The plurality of wheel drive devices include a first wheel drive device and a second wheel drive device, The first wheel drive device is the wheel drive device according to any one of claims 1 to 9, The second wheel drive device is a wheel drive unit that is a wheel drive device that drives wheels by only one motor.

Images