Wheel drive

Abstract

The present invention provides a wheel drive device that can effectively deal with lubricant leakage. The wheel drive device of the present invention comprises: a reduction mechanism (20) that reduces the speed of rotation transmitted from a driving source; a rotating body (22) to which the rotation reduced by the reduction mechanism (20) is transmitted, and the rotating body is integrated with the wheel; a fixed component (24-A, 24-B) that supports the rotating body (22) so that it can rotate freely; an oil seal (26) that is arranged between the rotating body (22) and the fixed component (24-A, 24-B) and seals the space containing the reduction mechanism (20); and lubricants (60-A, 60-B) that are sealed in an enclosed space (28) sealed by the oil seal (26), wherein the lubricants (60-A, 60-B) include at least two lubricants with different mixed consistencies, and the amount of the lubricants enclosed is less than 35% of the volume of the enclosed space.

Description

[0001] This application claims the benefit of priority based on Japanese Patent Application No. 2017-045126, filed on March 9, 2017. The entire contents of this Japanese patent application are incorporated herein by reference. Technical Field

[0002] The invention relates to a wheel drive device. Background Art

[0003] Conventionally, a wheel drive device that drives the wheels of a transport trolley or the like is known to have a reduction mechanism incorporated therein. This type of wheel drive device is sometimes used in locations where cleanliness is required (e.g., a clean room). In such cases, it is sometimes necessary to address leakage of the lubricant enclosed within the wheel drive device. As a wheel drive device that takes such measures, Patent Document 1 discloses a wheel drive device in which a bearing that supports a rotating body so that it can rotate freely is provided as a bearing with a seal, and a sealing member is arranged on the side closer to the external space than the bearing with the seal.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-71810

[0005] The present inventors have studied and found that the technology of Patent Document 1 does not provide sufficient countermeasures against lubricant leakage and that there is room for improvement. Summary of the Invention

[0006] One embodiment of the present invention has been made in view of such circumstances, and one object of the present invention is to provide a wheel drive device that can effectively cope with leakage of lubricant.

[0007] One embodiment of the present invention relates to a wheel drive device comprising: a reduction mechanism that reduces the speed of rotation transmitted from a drive source; a rotating body to which the rotation reduced by the reduction mechanism is transmitted, and the rotating body is integrated with a tire; a fixed component that supports the rotating body so that it can rotate freely; an oil seal that is arranged between the rotating body and the fixed component and seals the space in which the reduction mechanism is accommodated; and a lubricant that is sealed in an enclosed space sealed by the oil seal, wherein the lubricant includes at least two lubricants with different mixed viscosities, and the amount of the lubricant sealed is less than 35% of the volume of the enclosed space.

[0008] Another embodiment of the present invention relates to a wheel drive device comprising: a reduction mechanism that reduces the speed of rotation transmitted from a drive source; a rotating body, to which the rotation reduced by the reduction mechanism is transmitted, and the rotating body is integrated with a tire; a fixing component that supports the rotating body so that it can rotate freely; an oil seal that is arranged between the rotating body and the fixing component and seals the space containing the reduction mechanism; and a lubricant that is sealed in the enclosed space sealed by the oil seal, wherein the wheel drive device further comprises a flinger that rotates integrally with the rotating body and flings off the lubricant leaked from the arrangement portion of the oil seal.

[0009] Another embodiment of the present invention relates to a wheel drive device comprising: a reduction mechanism that reduces the speed of rotation transmitted from a drive source; a rotating body to which the rotation reduced by the reduction mechanism is transmitted, and the rotating body is integrated with a tire; a fixed component that supports the rotating body so that it can rotate freely; an oil seal that is arranged between the rotating body and the fixed component and seals the space in which the reduction mechanism is accommodated; and a lubricant that is sealed in the enclosed space sealed by the oil seal, wherein the wheel drive device has an oil tank that receives the lubricant leaking from the arrangement position of the oil seal.

[0010] According to the present invention, it is possible to provide a wheel drive device that effectively addresses leakage of lubricant. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a front cross-sectional view showing the wheel drive device according to the first embodiment.

[0012] Figure 2 This is an enlarged view of the speed reduction mechanism and its surrounding structure in the first embodiment.

[0013] Figure 3 It is a diagram for explaining the distribution of the lubricant in the sealed space according to the first embodiment.

[0014] Figure 4 A diagram for explaining the path that lubricant passes through after leaking from the location where the first oil seal is arranged.

[0015] Figure 5 for Figure 1 A partial enlarged view of .

[0016] Figure 6 To observe from the side opposite to the vehicle body Figure 1 A partial cross-sectional view of a portion of a wheel drive device.

[0017] Figure 7 To observe from the side opposite to the vehicle body Figure 1 An external view of a portion of a wheel drive unit.

[0018] Figure 8 It is a plan view showing the first oil tank and the second oil tank of the first embodiment.

[0019] Figure 9 for Figure 8 AA line section view.

[0020] Figure 10(a) to Figure 10(c) These are views of the trough support member as viewed from the side opposite to the rotating body, the rotating body side, and the side in the traveling direction Y, respectively.

[0021] 11( a ) and 11 ( b ) are views showing a first oil groove and a portion of a groove support member according to the first embodiment.

[0022] Figure 12 It is a partial front sectional view of the wheel drive device according to the second embodiment.

[0023] Figure 13 It is a side cross-sectional view showing a circumferential end portion of a wheel cover according to a second embodiment.

[0024] In the figure: 10-wheel drive device, 14-tire, 20-reduction mechanism, 22-rotating body, 28-enclosed space, 32-A, 32-B-eccentric body, 34-external gear, 36-eccentric body bearing, 44-wheel hub, 46-housing, 48-wheel cover body, 48a-peripheral cover body part, 48b-side cover body part, 48d-opening part, 50-main bearing, 60-A-hard lubricant, 60-B-soft lubricant, 62-swing plate, 62a-annular part, 62b-bent part, 64-interface, 66-first gap, 68-second gap, 70-first oil groove, 70c-hanging part, 72-second oil groove, 74-groove support part, 74e-inclined part, 76-magnet, 78-lubricant absorber. DETAILED DESCRIPTION

[0025] In the following embodiments and variations, identical components are denoted by identical reference numerals, and repeated descriptions are omitted. Furthermore, in the drawings, for ease of description, some components are omitted, or the dimensions of the components are exaggerated or reduced as appropriate. Furthermore, components with common features are distinguished by prefixing their names with "1st," "2nd," etc., and suffixing their reference numerals with "-A," "-B," etc., and these are omitted when referring to them collectively.

[0026] (First embodiment)

[0027] Figure 1This is a front cross-sectional view of the wheel drive device 10 according to the first embodiment. The wheel drive device 10 of this embodiment is assembled to the vehicle body 12 of the transport vehicle and is used to drive the tire 14 of the transport vehicle. The transport vehicle of this embodiment is a rail-guided vehicle, and the tire 14 of this embodiment travels on a running surface 16a of a track 16 laid on the ground. Hereinafter, the direction along the rotation centerline La of the tire 14 is referred to as the axial direction X of the tire 14, and the circumferential and radial directions around this rotation centerline a are referred to as "circumferential direction" and "radial direction," respectively. The running direction of the tire 14 is a horizontal direction perpendicular to this axial direction X.

[0028] The wheel drive device 10 primarily includes an input shaft 18, a reduction gear mechanism 20, a rotating body 22, wheel carriers 24-A and 24-B, and a first oil seal 26. The wheel drive device 10 of this embodiment primarily features the lubricant (not shown) enclosed in an enclosed space 28 (described later) on the inner circumference of the rotating body 22, and the external structure of the enclosed space 28. The former will be described first.

[0029] The input shaft 18 receives rotation transmitted from the output shaft 30 of the drive source. While the drive source in this embodiment is a motor, it may also be a gear motor, for example, in which a motor and a reduction gear are integrated. The output shaft 30 of the drive source, which protrudes outward from the vehicle body 12 in the vehicle width direction, is connected to the input shaft 18. The input shaft 18 is rotatable integrally with the output shaft 30, and the rotation of the drive source is transmitted from the output shaft 30 to the input shaft 18. The rotation centerline of the input shaft 18 is coaxial with the rotation centerline La of the tire 14.

[0030] Figure 2 This is an enlarged view of the reduction mechanism 20 and its surrounding structures. The reduction mechanism 20 is used to reduce the speed of rotation transmitted from the drive source. The reduction mechanism 20 of this embodiment is an eccentric swing type reduction mechanism. The reduction mechanism 20 mainly includes eccentric bodies 32-A and 32-B, an external gear 34, an eccentric body bearing 36, and an internal gear 38.

[0031] The eccentric body 32 is integrally formed with the input shaft 18 and is rotatable integrally with the input shaft 18. The eccentric bodies 32-A and 32-B include a first eccentric body 32-A and a second eccentric body 32-B that are adjacent to each other in the axial direction X. The axes of the first eccentric body 32-A and the second eccentric body 32-B are eccentric in opposite directions with respect to the rotation centerline La of the tire 14.

[0032] The external gears 34 are independently provided for the first and second eccentric bodies 32-A, 32-B, respectively. The external gears 34 are supported by the corresponding eccentric bodies 32-A and 32-B via eccentric bearings 36 and are oscillated by the eccentric bodies 32-A and 32-B. Specifically, when the corresponding eccentric bodies 32-A and 32-B rotate about the rotational centerline La of the tire 14, the external gears 34 oscillate so that their own axes rotate about the rotational centerline La of the tire 14.

[0033] The external gear 34 has a central hole 34 a formed at its axis and extending through the external gear 34 in the axial direction X. Eccentric bodies 32 -A and 32 -B and an eccentric body bearing 36 are disposed inside the central hole 34 a of the external gear 34 .

[0034] The external gear 34 also has a plurality of pin holes 34b extending through the external gear 34 in the axial direction X. The pin holes 34b are arranged circumferentially at intervals at positions offset from the axis of the external gear 34. The inner pin 40 is inserted through the pin holes 34b, with clearance between the inner pin 40 and the pin holes 34b. An inner roller 42 is provided on the outer circumference of the inner pin 40, rotatably supported by the inner pin 40. The inner pin 40 is supported by the pair of wheel carriers 24, with both ends fixed to the pair of wheel carriers 24.

[0035] The eccentric bearings 36 are independently provided for the first eccentric 32 -A and the second eccentric 32 -B, respectively. The eccentric bearings 36 are provided between the corresponding eccentrics 32 -A and 32 -B and the external gear 34 .

[0036] The eccentric bearing 36 of this embodiment is a roller bearing. It includes a plurality of first rolling elements 36a, a retainer 36b, a first inner ring 36c, and a first outer ring 36d. The first rolling elements 36a are spaced apart around the rotational centerline La of the tire 14. The retainer 36b maintains the relative positions of the plurality of first rolling elements 36a and supports the plurality of first rolling elements 36a for free rotation.

[0037] The first inner ring 36c of this embodiment is formed of a component separate from the eccentric body 32 and is integrated with the outer peripheral surface of the eccentric body 32 by interference fit, etc. The outer peripheral surface of the first inner ring 36c constitutes a first inner rolling surface 36e on which the first rolling element 36a rolls in the circumferential direction.

[0038] The first outer ring 36d of this embodiment is formed by the inner circumferential surface of the center hole 34a of the external gear 34. The first outer ring 36d is formed from a portion of the same component as the external gear 34. The inner circumferential surface of the first outer ring 36d forms a first outer rolling surface 36f on which the first rolling element 36a rolls in the circumferential direction.

[0039] The internal gear 38 meshes internally with the external gear 34. In this embodiment, the internal gear 38 includes a plurality of outer pins 38a supported on the inner circumference of a housing 46 (described later) and a plurality of outer rollers 38b rotatably supported on the outer pins 38a. The outer rollers 38b each constitute the internal teeth of the internal gear 38. In this embodiment, the number of internal teeth of the internal gear 38 (the number of outer rollers 38b) exceeds the number of external teeth of the external gear 34 by one.

[0040] refer to Figure 1 The rotation decelerated by the speed reduction mechanism 20 is transmitted to the rotating body 22. The rotating body 22 is integrated with the tire 14. The rotating body 22 is annular as a whole, and the speed reduction mechanism 20 and the wheel carrier 24 are arranged on the inner circumference of the rotating body 22.

[0041] The rotating body 22 includes, in addition to the tire 14 that contacts the running surface 16 a , a hub 44 to which the tire 14 is mounted, and a housing 46 having the internal gear 38 of the speed reduction mechanism 20 provided on its inner circumference.

[0042] The tire 14 is attached to the outer periphery of the wheel hub 44 by bonding or other means. The tire 14 is made of a soft material, and the wheel hub 44 is made of a harder material than the soft material of the tire 14. In this example, the soft material is an elastomer such as polyurethane rubber, and the hard material is a metal such as steel.

[0043] The housing 46 is a housing of the speed reduction mechanism 20 and also functions as an output member for outputting the rotation reduced by the speed reduction mechanism 20. The housing 46 is arranged on the inner circumference of the hub 44 and is integrated with the hub 44 by bolts B1.

[0044] The wheel carriers 24-A and 24-B include an inner wheel carrier 24-A positioned closer to the vehicle body than the external gear 34, and an outer wheel carrier 24-B positioned on the opposite side of the vehicle body than the external gear 34. The vehicle body side in this specification refers to the vehicle body 12 side in the axial direction X relative to the component in question (here, the external gear 34), and the opposite side to the vehicle body refers to the side opposite to the vehicle body 12 in the axial direction X. The inner wheel carrier 24-A is fixed to the wheel cover 48 described later by wheel carrier bolts B2. The outer wheel carrier 24-B is fixed to a portion of the wheel cover 48 by interlocking.

[0045] refer to Figure 2 Main bearings 50 are provided between the outer shell 46 of the rotating body 22 and the inner wheel carrier 24-A, and between the outer shell 46 of the rotating body 22 and the outer wheel carrier 24-B, for supporting the rotating body 22 so that it can rotate freely. The inner wheel carrier 24-A and the outer wheel carrier 24-B function as fixed components that support the rotating body 22 so that it can rotate freely via the main bearings 50.

[0046] The main bearing 50 of this embodiment is a roller bearing. It includes a plurality of second rolling elements 50a, a second inner ring 50b, and a second outer ring 50c. The second rolling elements 50a are spaced apart around the rotational centerline La of the tire 14. In this embodiment, the second inner ring 50b is formed from a separate component from the wheel carrier 24 and is integrated with the outer circumference of the wheel carrier 24 through an interference fit or other means. The outer circumference of the second inner ring 50b forms a second inner rolling surface 50d, on which the second rolling elements 50a roll circumferentially. In this embodiment, the second outer ring 50c is formed from a separate component from the housing 46 of the rotating body 22 and is integrated with the inner circumference of the housing 46 through an interference fit or other means. The inner circumference of the second outer ring 50c forms a second outer rolling surface 50e, on which the second rolling elements 50a roll circumferentially. The space between the second inner ring 50b and the second outer ring 50c is open to both sides in the axial direction X.

[0047] A first through-hole 24a is formed in the inner wheel carrier 24-A, extending radially through its center. A first input shaft bearing 52-A is disposed inside the first through-hole 24a. The inner wheel carrier 24-A rotatably supports the input shaft 18 via the first input shaft bearing 52-A. The first through-hole 24a is covered by a shaft cover 54, which is positioned closer to the vehicle body than the first input shaft bearing 52-A. The input shaft 18 extends through the shaft cover 54 in the axial direction X. A second oil seal 56 is disposed between the shaft cover 54 and the input shaft 18, sealing the first through-hole 24a.

[0048] A second through-hole 24b is formed in the outer wheel carrier 24-B, extending radially through its center. A second input shaft bearing 52-B is disposed inside the second through-hole 24b. The outer wheel carrier 24-B rotatably supports the input shaft 18 via the second input shaft bearing 52-B. The second through-hole 24b is sealed by the second input shaft bearing 52-B and a seal cap 58 located on the side of the input shaft 18 that is opposite to the vehicle body.

[0049] The first oil seal 26 is arranged between the outer shell 46 of the rotating body 22 and the inner wheel frame 24-A, and between the outer shell 46 of the rotating body 22 and the outer wheel frame 24-B. The first oil seal 26 seals the space in which the reduction mechanism 20 is housed, thereby forming an enclosed space 28 for the lubricant (not shown). In this embodiment, a plurality of first oil seals 26 are arranged side by side along the axial direction X, but the number thereof is not particularly limited. The first oil seal 26 is composed of an annular elastomer. The shape of the first oil seal 26 in the cross section along the rotation center line La of the tire 14 is a groove-like shape that is open toward the enclosed space 28 sealed by the first oil seal 26.

[0050] Next, the operation of the wheel drive device 10 will be described.

[0051] When the rotation of the drive source is transmitted from the output shaft 30 to the input shaft 18, the input shaft 18 rotates. When the input shaft 18 rotates, the rotation of the input shaft 18 is reduced in speed by the reduction gear mechanism 20 and then transmitted to the housing 46 of the rotating body 22. When the rotation is transmitted from the reduction gear mechanism 20 to the rotating body 22, the tire 14, which is integrated with the rotating body 22, rotates, causing the tire 14 to travel on the running surface 16a.

[0052] Here, when the input shaft 18 rotates, the eccentric body 32 of the reduction mechanism 20 rotates along with the input shaft 18 about the rotation centerline La. As the eccentric body 32 rotates about the rotation centerline La, the external gear 34 oscillates so that the axis of the external gear 34 rotates about the rotation centerline La. As the external gear 34 oscillates, the meshing position between the external gear 34 and the internal gear 38 gradually shifts. As a result, with each rotation of the input shaft 18, the internal gear 38 rotates relative to the external gear 34 (rotates on its own axis) by an amount corresponding to the difference in the number of teeth between the internal gear 38 and the external gear 34. This rotational component is transmitted to the housing 46 of the rotating body 22. At this time, the rotation of the input shaft 18 (i.e., the rotation transmitted from the drive source) is reduced in speed by a reduction ratio corresponding to the difference in the number of teeth between the external gear 34 and the internal gear 38, and is then transmitted from the internal gear 38 to the rotating body 22.

[0053] Figure 3 This diagram illustrates the distribution of lubricants 60-A and 60-B within enclosed space 28. Enclosed space 28 is a space defined by the rotating body 22 and the wheel carrier 24 and is sealed by the first oil seal 26, the shaft cover 54, the second oil seal 56, the seal cover 58, and the like. Enclosed space 28 can also be interpreted as a closed space defined by objects other than lubricants 60-A and 60-B. Objects other than lubricants 60-A and 60-B include the input shaft 18, the reduction gear 20, the rotating body 22, the wheel carrier 24, the first oil seal 26, the main bearing 50, the input shaft bearing 52, the shaft cover 54, the second oil seal 56, the seal cover 58, and the like.

[0054] The enclosed space 28 includes: an accommodating space 28a for accommodating the reduction mechanism 20, and a gap space 28b provided between the rotating body 22 and the wheel carrier 24. The accommodating space 28a of this embodiment is formed between a pair of wheel carriers 24 on the inner circumferential side of the rotating body 22. The gap space 28b is provided radially outward relative to the eccentric body 32 and the eccentric body bearing 36 within the accommodating space 28a, and extends further outward in the axial direction X than the accommodating space 28a. The first oil seal 26 is provided at the end position of the gap space 28b in the axial direction X. The main bearing 50 is provided in the gap space 28b at a position closer to the accommodating space 28a than the first oil seal 26. The main bearing 50 is arranged between the rotating body 22 and the wheel carrier 24, and is arranged at a position closer to the enclosed space 28 than the first oil seal 26.

[0055] The lubricants 60-A and 60-B in this embodiment are grease. The lubricants 60-A and 60-B include a hard lubricant 60-A and a soft lubricant 60-B having different mixing consistencies. Figure 3 In the figure, the area marked with double hatching represents the hard lubricant 60-A, and the area marked with a dotted pattern represents the soft lubricant 60-B. Here, "mixed consistency" is a characteristic value indicating the hardness and fluidity of the grease. The mixed consistency is a value expressed in millimeters when the tip of a specified cone is inserted into the grease in a specified manner and the penetration depth is magnified 10 times. The "mixed consistency" is a measured value measured immediately after the grease is mixed 60 times under specified conditions. The National Lubricating Grease Institute (NLGI) classifies greases according to the numerical range of mixed consistency and using mixed consistency grades, and the Japanese Industrial Standards (JIS) also follow this standard. In this embodiment, the mixed consistency measured according to the conditions specified in the standard JIS K2220 and the mixed consistency grades specified in JIS K2220 are used to identify the lubricant 60.

[0056] Hard lubricant 60-A uses a grease with a relatively low mixing consistency, while soft lubricant 60-B uses a grease with a higher mixing consistency than that of hard lubricant 60-A. Specifically, hard lubricant 60-A has a higher viscosity and lower fluidity than soft lubricant 60-B, making it a hard lubricant. Soft lubricant 60-B has a lower viscosity and higher fluidity than hard lubricant 60-A, making it a soft lubricant. Hard lubricant 60-A uses a lubricant with a mixing consistency grade within a relatively low mixing consistency range. Soft lubricant 60-B uses a lubricant with a mixing consistency grade greater than the mixing consistency range corresponding to the mixing consistency grade of hard lubricant 60-A. Specifically, in this embodiment, hard lubricant 60-A uses a lubricant with a mixing consistency grade of 2, with a mixing consistency range of 265 to 295 [1 / 10 mm]. In this embodiment, the soft lubricant 60 -B uses a lubricant with a mixed consistency grade of 00, and the mixed consistency range is 400 to 430 [1 / 10 mm].

[0057] The wheel drive device 10 of this embodiment has a characteristic in the relationship between the amount of lubricants 60-A and 60-B enclosed and the volume of the enclosed space 28 enclosing the lubricants 60-A and 60-B (hereinafter referred to as the enclosed space volume). This "enclosed amount of lubricants 60-A and 60-B" represents the total amount of the hard lubricant 60-A and the soft lubricant 60-B enclosed. This "enclosed space volume" does not include the portion occupied by the "objects other than the lubricants 60-A and 60-B" (such as the input shaft 18 and the reduction mechanism 20) that form the enclosed space 28.

[0058] The amount of lubricant 60-A and 60-B enclosed is set to no more than 35% of the volume of the enclosed space. More preferably, it is set to no more than 30% of the volume of the enclosed space. This setting was made by the inventors based on the results of experimental research. In this experiment, a wheel drive device 10 equipped with various reduction mechanisms was used. The amount of lubricant 60-A and 60-B enclosed relative to the volume of the enclosed space was varied to determine whether lubricant leaked from the location where the first oil seal 26 was located. In this experiment, the input shaft 18 was repeatedly rotated forward for 30 seconds at a rotational speed of 2680 [rpm] and reversely for 30 seconds at the same rotational speed over two days to determine whether lubricant leakage occurred. The various reduction mechanisms included, in addition to the eccentric oscillating reduction mechanism of this embodiment, parallel shaft gear reduction mechanisms, orthogonal shaft gear reduction mechanisms, planetary gear reduction mechanisms, and the like. The results showed that lubricant leakage was confirmed when the amount of lubricant 60 enclosed reached 40% of the volume of the enclosed space. On the other hand, when the amount of lubricant 60 sealed was 35% or less of the sealed space volume, no lubricant leakage was observed. Based on this experimental result, the above-mentioned amount of lubricant 60 sealed was set.

[0059] The present inventors, through the aforementioned experimental studies, have come to the following conclusion: when only a single type of lubricant is enclosed within the enclosed space 28, if the amount of lubricants 60-A and 60-B enclosed is set to less than 35% of the volume of the enclosed space, the multiple areas within the enclosed space 28 requiring lubrication cannot stably achieve the required lubricity. The present inventors believe that this is because when only a single type of lubricant is used and the amount of lubricant 60 enclosed is set to less than 35% of the volume of the enclosed space, it is difficult to ensure that the lubricant reaches all areas requiring lubrication. Furthermore, the areas requiring lubrication herein are areas predetermined within the enclosed space 28 as areas particularly requiring lubrication. In this embodiment, the eccentric bearing 36 and the main bearing 50 are identified as areas requiring lubrication.

[0060] In contrast, in this embodiment, as described above, a hard lubricant 60-A with low fluidity and a soft lubricant 60-B with high fluidity are used simultaneously. This allows the soft lubricant 60-B to flow and reach a portion of the area requiring lubrication, while the hard lubricant 60-A is applied to other areas requiring lubrication that are difficult for the soft lubricant 60-B to reach. This ensures lubricity regardless of the flow state of the soft lubricant 60-B. As a result, a design is possible that stably achieves the required lubricity at multiple areas requiring lubrication within the enclosed space 28 while allowing the enclosed amounts of lubricants 60-A and 60-B to be set to no more than 35% of the enclosed space volume. Furthermore, a design that stably achieves the same required lubricity while allowing the enclosed amounts of lubricants 60-A and 60-B to be set to no more than 30% of the enclosed space volume is also possible.

[0061] Here, as the eccentric body 32 rotates, a large load acts on the eccentric body bearing 36, so the eccentric body bearing 36 needs to ensure lubrication. In addition, within the enclosed space 28, the circumferential speed of the eccentric body bearing 36 is greater than the circumferential speed of other parts. Therefore, due to its centrifugal force and other factors, the lubricant will be thrown off, which can easily cause lubrication faults. Therefore, in this embodiment, the eccentric body bearing 36 is identified as one of the parts within the enclosed space 28 that particularly require lubrication. Even in the case of causing the soft lubricant 60-B to flow as described above, the eccentric body bearing 36 of this embodiment corresponds to a part that requires lubrication and is difficult for the soft lubricant 60-B to reach.

[0062] A hard lubricant 60-A is applied to the eccentric bearing 36, identified as the area requiring lubrication. Specifically, the hard lubricant 60-A is applied to the area of ​​the eccentric bearing 36 that comes into rolling contact with the first rolling element 36a. More specifically, the hard lubricant 60-A is applied to the entire outer circumference of the plurality of first rolling elements 36a. Furthermore, the hard lubricant 60-A is applied continuously along the entire circumference of the first inner rolling surface 36e and the first outer rolling surface 36f on which the first rolling elements 36a roll. This ensures that the required lubricity is consistently achieved in the eccentric bearing 36, where lubrication failure is prone to occur. Furthermore, the hard lubricant 60-A is also applied to the contact areas between the plurality of first rolling elements 36a and the retainer 36b.

[0063] Furthermore, when the tire 14 is running, a large load is likely to act on the main bearing 50, so lubricity must be ensured for the main bearing 50. Therefore, in this embodiment, the main bearing 50 is identified as one of the areas within the enclosed space 28 that require particular lubrication, and a hard lubricant 60-A is also applied to the main bearing 50. Specifically, the hard lubricant 60-A is applied to the area of ​​the main bearing 50 that comes into rolling contact with the second rolling elements 50a. More specifically, the hard lubricant 60-A is applied to the entire outer circumference of the plurality of second rolling elements 50a. Furthermore, the hard lubricant 60-A is continuously applied to the entire circumference of the second inner rolling surface 50d and the second outer rolling surface 50e on which the second rolling elements 50a roll. Applying the hard lubricant 60-A to the main bearing 50 ensures lubricity in areas of the main bearing 50 that require lubrication, and also achieves the following benefits.

[0064] When the rotating body 22 is in a stationary state, as shown in FIG. Figure 3 As shown, the soft lubricant 60-B is present in the lower portion of the gap space 28b within the enclosed space 28, but not in the rest of the gap space 28b. In this state, when the rotating body 22 rotates, the soft lubricant 60-B, influenced by centrifugal force and other factors, flows to fill the rest of the gap space 28b where the soft lubricant 60-B is absent. At this point, a portion of the soft lubricant 60-B flows within the gap space 28b toward the first oil seal 26. This influence applies dynamic pressure from the soft lubricant 60-B to the first oil seal 26 in the axial direction X, toward the side opposite the enclosed space 28 (i.e., toward the external space).

[0065] Here, if the hard lubricant 60-A is applied to the main bearing 50, the area of ​​the passageway within the main bearing 50 through which the soft lubricant 60-B can flow is reduced by an amount corresponding to the volume of the hard lubricant 60-A. This makes it more difficult for the soft lubricant 60-B to flow through the interior of the main bearing 50 toward the first oil seal 26, compared to a case where the hard lubricant 60-A is not applied. This delays the soft lubricant 60-B from filling the space 28c closer to the first oil seal 26 than the main bearing 50. As a result, the dynamic pressure applied to the first oil seal 26 by the soft lubricant 60-B in the initial stages after the rotating body 22 begins rotating is reduced, thereby suppressing lubricant leakage from the location where the first oil seal 26 is located.

[0066] The lower limit of the amount of lubricant 60-A, 60-B enclosed is not particularly limited from the perspective of preventing leakage of lubricant 60-A, 60-B. However, the enclosed amount can be set to at least 25% of the volume of the enclosed space. Meeting this condition allows lubricant 60-A, 60-B to easily reach all areas requiring lubrication within the enclosed space 28, thereby ensuring the required lubricity in all areas requiring lubrication. In this embodiment, areas requiring lubrication include, in addition to the eccentric bearing 36 and the main bearing 50, the meshing areas of the gears of the speed reduction mechanism 20 and the input shaft bearing 52.

[0067] According to the wheel drive device 10 of the present embodiment, the amount of lubricants 60 -A and 60 -B sealed is set to 35% or less of the sealed space volume, and thus leakage of lubricant from the location where the first oil seal 26 is disposed can be effectively addressed.

[0068] Next, the external structure of the enclosed space 28 of the wheel drive device 10 will be described.

[0069] Here, an example of a path that the lubricant takes after leaking from the location where the first oil seal 26 is disposed to the outside will be considered. Figure 4 This diagram illustrates the path of lubricant 60 after leaking from the location of the first oil seal 26. This leaked lubricant 60 flows axially outward along the inner periphery of the rotating body 22 and onto the side surface 22a of the rotating body 22 (see arrow Pa1). When the rotating body 22 is stationary, the lubricant 60 that has flowed onto the side surface 22a of the rotating body 22 flows due to its own weight to the outer periphery of the rotating body 22 and attempts to flow toward the contact surface 22b of the rotating body 22 that contacts the running surface 16a (see arrow Pa2). If the lubricant 60 flows onto the contact surface 22b of the rotating body 22, it may cause adverse effects, so measures must be taken to address this issue.

[0070] Figure 5 for Figure 1 A partial enlarged view of the Figure 1 and Figure 5 As shown, the wheel drive device 10 of this embodiment includes a flinger plate 62 fixed to the rotating body 22 and capable of rotating integrally with the rotating body 22. The flinger plates 62 of this embodiment are respectively fixed to the side surfaces 22a on both sides of the rotating body 22 in the axial direction X. The flinger plates 62 are used to fling off lubricant 60 that leaks from the location where the first oil seal 26 is arranged.

[0071] The flinger plate 62 is an annular plate extending radially outward. The flinger plate 62 of this embodiment includes a flat, annular ring portion 62a and a curved portion 62b that curves from the outer peripheral end of the ring portion 62a toward the side opposite the rotating body in the axial direction X. The term "opposite the rotating body" as used herein refers to the side of the component (here, the annular portion 62a) opposite the side of the rotating body 22 in the axial direction X.

[0072] The annular portion 62a overlaps with the side surface 22a of the rotating body 22 and is removably secured to the side surface 22a of the rotating body 22 by bolts B1 extending through the annular portion 62a. In this embodiment, the inner circumferential surface of the annular portion 62a is aligned with the inner circumferential surface 22c of a portion of the rotating body 22 adjacent to the flinger 62 in the axial direction X. The curved portion 62b has a tapered shape that increases in diameter toward the side opposite the rotating body. In this embodiment, the curved portion 62b has a continuous truncated cone shape around the entire circumference of the rotation centerline La of the tire 14.

[0073] In this embodiment, the outer peripheral end 62c of the flinger plate 62 is disposed at a position radially offset inward from the interface 64 between the tire 14 and the wheel hub 44. Alternatively, the outer peripheral end 62c of the flinger plate 62 is disposed at a position radially offset inward from the contact surface 22b of the rotating body 22. The outer peripheral end 62c of the flinger plate 62 in this embodiment is the outer peripheral end of the curved portion 62b.

[0074] The lubricant 60 that leaks to the outside from the location where the first oil seal 26 is located flows onto the outer surface of the rotator 22 while flowing along the outer surface of the slinger 62. As the rotator 22 rotates, the slinger 62 rotates integrally with the rotator 22. Therefore, the lubricant 60 that has flowed onto the outer surface of the slinger 62 is spun radially outward from the outer peripheral end 62c of the slinger 62 in the direction Pb. Thus, the lubricant 60 is separated from the rotator 22 before it flows onto the contact surface 22b of the rotator 22. Therefore, according to this embodiment, even in the event of lubricant 60 leakage, it is possible to prevent the lubricant 60 from flowing onto the contact surface 22b of the rotator 22 and causing adverse effects, and to effectively address leakage of the lubricant 60.

[0075] Furthermore, the fling plate 62 has a curved portion 62b that curves from the annular portion 62a to the side opposite to the rotating body. Here, consider a case where the fling plate 62 does not have the curved portion 62b. In order to separate the lubricant 60 from the rotating body 22, the outer peripheral end portion 62c of the fling plate 62 needs to be arranged at a position separated from the side portion 22a of the rotating body 22. If the fling plate 62 does not have the curved portion 62b, in order to meet this condition, Figure 5For example, at least the outer peripheral end 62c of the slinger plate 62 (the outer peripheral end of the annular portion 62a) needs to be arranged at a position radially offset from the interface 64 between the tire 14 and the wheel hub 44. Therefore, the outer diameter of the slinger plate 62 will become larger.

[0076] In contrast, if the flinger plate 62 has a curved portion 62b, the outer peripheral end 62c of the flinger plate 62 can be positioned away from the side surface 22a of the rotating body 22 regardless of the shape of the side surface 22a of the rotating body 22. Therefore, when separating the lubricant 60 from the rotating body 22, the outer diameter of the flinger plate 62 can be reduced, enabling a smaller flinger plate 62. Furthermore, since the outer diameter of the flinger plate 62 is reduced, the circumferential velocity of the outer peripheral end 62c of the flinger plate 62, where the lubricant 60 is flung away, can be reduced. This reduces the velocity of the lubricant 60 flung off the flinger plate 62, thereby preventing the lubricant 60 from splashing outward from the area where it is received.

[0077] Next, other features of the wheel drive device 10 will be described.

[0078] like Figure 1 As shown, the wheel drive device 10 includes a wheel cover 48 that covers the rotating body 22 . Figure 6 To observe from the side opposite to the vehicle body Figure 1 A partial cross-sectional view of a portion of the wheel drive device 10. Figure 1 and Figure 6 As shown, the wheel cover 48 includes an outer peripheral cover portion 48a that covers the rotating body 22 from the outer peripheral side, side cover portions 48b and 48c that cover the rotating body 22 from the axial direction X, and an opening portion 48d that allows the rotating body 22 to protrude downward.

[0079] The outer peripheral cover portion 48a has a downwardly open arc shape in a cross section perpendicular to the axial direction X. Inner flange portions 48f projecting from one circumferential end 48e toward the other circumferential end 48e are provided at both circumferential ends 48e of the outer peripheral cover portion 48a.

[0080] The side cover portions 48b and 48c include an inner side cover portion 48b, which is positioned closer to the vehicle body 12 than the rotating body 22 in the axial direction X, and an outer side cover portion 48c, which is positioned closer to the rotating body 22 than the vehicle body in the axial direction X. The inner wheel carrier 24-A is fixed to the inner side cover portion 48b by wheel carrier bolts B2, while a portion of the outer wheel carrier 24-B is fixed to the outer side cover portion 48c by interlocking engagement. Thus, the wheel cover 48 functions as an integral component with the wheel carrier 24 (fixed component).

[0081] A cylindrical portion 48g is provided radially inwardly of the inner side cover portion 48b, extending in the axial direction X. The input shaft 18 is inserted into the inner side of the cylindrical portion 48g. The vehicle-side end of the cylindrical portion 48g abuts against the vehicle body 12 and is bolted to the vehicle body 12. Thus, the wheel cover 48 is assembled to the vehicle body 12.

[0082] like Figure 5 and Figure 6 As shown, an opening 48d is formed at the lower end of the wheel cover 48 and opens downward. The opening 48d is formed by both circumferential ends 48e of the outer cover portion 48a and the lower edges 48h of the side cover portions 48b and 48c. A first gap 66 is formed between the lower edge 48h of the side cover portion 48b, which forms the opening 48d, and the rotating body 22. A second gap 68 is formed between the circumferential end 48e of the outer cover portion 48a, which forms the opening 48d, and the rotating body 22. The first gap 66 is formed on both sides of the rotating body 22 in the axial direction, and the second gap 68 is formed on both sides of the rotating body 22 in the traveling direction.

[0083] Here, we will focus on the path of the lubricant 60 leaking from the location of the first oil seal 26. The path of the lubricant 60 leaking to the outside includes a first path, which passes through the first gap 66 between the wheel cover 48 and the rotating body 22, and a second path, which passes through the second gap 68 between the wheel cover 48 and the rotating body 22. The lubricant 60 flowing along the side surface 22a of the rotating body 22 and the lubricant 60 dripping along the inner surface of the side cover 48b of the wheel cover 48 tend to flow through the first path. The lubricant 60 dripping along the inner circumferential surface of the outer cover 48a of the wheel cover 48 tends to flow through the second path. The lubricant 60 adhering to the inner surface of the side cover 48b and the inner circumferential surface of the outer cover 48a of the wheel cover 48 is the lubricant that has been thrown off by the slinger 62 and is part of the lubricant 60 that leaked from the location of the first oil seal 26. That is, the lubricant 60 passing through both the first path and the second path is the lubricant leaked from the location where the first oil seal 26 is arranged.

[0084] The wheel drive device 10 includes oil grooves 70 and 72 for catching lubricant 60 leaking from the location where the first oil seal 26 is located. The oil grooves 70 and 72 include a first oil groove 70 that catches lubricant 60 passing through the first gap 66 and a second oil groove 72 that catches lubricant 60 passing through the second gap 68. Furthermore, the wheel drive device 10 includes a groove support member 74 that supports the first oil groove 70.

[0085] like Figure 5As shown, the first oil groove 70 of this embodiment is arranged on one side of the axial direction of the rotating body 22 at a position lower than the first gap 66. The first oil groove 70 of this embodiment is arranged at a position offset radially inward from the interface 64 between the tire 14 and the wheel hub 44. The first oil groove 70 of this embodiment is independently provided corresponding to the first gap 66 on both sides of the axial direction of the rotating body 22 (refer to FIG. Figure 1 ).

[0086] Figure 7 To observe from the side opposite to the vehicle body Figure 1 The first oil tank 70 is a long member that is elongated along the running direction Y of the tire 14. In other words, the first oil tank 70 extends along the running direction Y of the tire 14. Figure 5 、 Figure 7 and Figure 8 As shown, the first oil groove 70 has a first groove portion 70a for receiving the lubricant 60. The first groove portion 70a is in the shape of a box that is open upward, and the received lubricant can be stored inside. The first groove portion 70a is arranged below the outer peripheral end portion 62c of the flinger plate 62 in the vertical direction. As a result, the lubricant 60 flung from the outer peripheral end portion 62c of the flinger plate 62 in the radially outward direction Pb is received by the first groove portion 70a. In addition, the two end portions 70b of the first groove portion 70a in the longitudinal direction are arranged below the outer peripheral surface of the outer peripheral cover portion 48a of the wheel cover body 48.

[0087] Figure 8 FIG is a top view showing the first oil groove 70 and the second oil groove 72. Figure 6 and Figure 8 As shown, the second oil groove 72 of this embodiment is arranged below the second gap 68 on the side of the rotating body 22 in the travel direction Y. The second oil groove 72 of this embodiment is independently provided corresponding to the second gap 68 on both sides of the rotating body 22 in the travel direction Y.

[0088] The second oil groove 72 extends along the axial direction X of the tire 14. The second oil groove 72 includes a second groove portion 72a for receiving the lubricant 60 and a second fixing portion 72b fixed to the wheel cover 48. The second groove portion 72a is elongated in the axial direction X and is open upward. In this embodiment, the second groove portion 72a has two longitudinal end portions 72c that are open outward in the longitudinal direction.

[0089] Figure 9 for Figure 8AA cross-sectional view. In this embodiment, the second groove portion 72a is positioned above the first groove portion 70a of the first oil groove 70. As a result, the lubricant 60 within the second groove portion 72a flows from the longitudinal end portion 72c along the direction Pc into the first groove portion 70a. In this manner, the second oil groove 72 is configured to guide the lubricant within the second oil groove 72 into the first oil groove 70.

[0090] like Figure 6 As shown, the second fixing portion 72b is a plate-shaped portion that overlaps the inner flange portion 48f of the wheel cover 48 from below and is detachably fixed to the inner flange portion 48f by bolts B3. The second oil tank 72 is fixed to the circumferential end portion 48e of the outer peripheral cover portion 48a of the wheel cover 48.

[0091] Figure 10(a) to Figure 10(c) The figures are respectively a side view of the groove support member 74 viewed from the side opposite to the rotating body, the side of the rotating body, and the side in the travel direction Y. The groove support member 74 is a long member that is elongated along the travel direction Y of the tire 14. Figure 5 、 Figure 10(a) to Figure 10(c) As shown, the groove support member 74 includes a groove accommodating portion 74a that accommodates the first oil groove 70 therein. The groove accommodating portion 74a is in the shape of a groove that extends along the length of the groove support member 74 and is open upward. The groove accommodating portion 74a is positioned below the first gap 66. Furthermore, the groove accommodating portion 74a is positioned radially inward from the interface 64 between the tire 14 and the wheel hub 44.

[0092] The groove accommodating portion 74a includes a bottom wall portion 74b that supports the first oil groove 70; an inner wall portion 74c that rises from the rotating body side of the bottom wall portion 74b; and an outer wall portion 74d that rises from the side of the bottom wall portion 74b opposite the rotating body. The outer wall portion 74d extends upward further than the inner wall portion 74 and is positioned on the side opposite the rotating body side of the side cover portion 48b of the wheel cover 48. The outer wall portion 74d overlaps with the side cover portion 48b of the wheel cover 48 in the axial direction X and is removably secured to the wheel cover 48 by bolts B4. The groove support member 74 and the wheel cover 48 are integrated with the wheel frame 24. The first oil groove 70 is supported by the groove support member 74 integrated with the wheel frame 24.

[0093] The first oil groove 70 and the groove support member 74 of this embodiment are made of soft magnetic materials such as steel. Figure 5 and Figure 7As shown, the magnet 76 is attached to the lower surface of the first groove portion 70a of the first oil groove 70 by bonding or other means. The magnet 76 of this embodiment is a long, plate-like body that is elongated along the length of the first groove portion 70a. The magnet 76 of this embodiment is attached to the entire range of the first groove portion 70a, from one end to the other end in the length direction of the first groove portion 70a. The magnet 76 is attracted to the groove support member 74 by magnetic force. As a result, the first oil groove 70 is held to the groove support member 74 by the magnetic force of the magnet 76.

[0094] The groove accommodating portion 74a has inclined portions 74e rising from both ends of the bottom wall portion 74b in the longitudinal direction. The inclined portions 74e are plate-shaped and have a width dimension perpendicular to the longitudinal direction that is smaller than the width dimension of the bottom wall portion 74b in the longitudinal direction.

[0095] Figures 11(a) and 11(b) illustrate a portion of the first oil groove 70 and the groove support member 74. The inclined portion 74e of the groove support member 74 is inclined upward and outward in the longitudinal direction of the groove support member 74. Here, the term "outward in the longitudinal direction" refers to a portion further outward in the longitudinal direction of the groove support member 74 than the space within the groove accommodating portion 74a.

[0096] Here, consider the case where one end of the first oil groove 70 is pulled in the pull-out direction Pd, which is one side in the longitudinal direction of the groove support member 74. As shown in Figure 11(a), if one end of the first oil groove 70 is pulled so that it contacts the inclined portion 74e of the groove support member 74, and then the first oil groove 70 is pulled strongly in the same direction, the first oil groove 70 is guided upward by the inclined portion 74e. At this time, the first oil groove 70 is separated from the bottom wall portion 74b of the groove support member 74, and the holding force of the magnet 76 is weakened, making it easier to pull the first oil groove 70 out. By continuing to pull the first oil groove 70 in the pull-out direction Pd, the first oil groove 70 is removed from the groove support member 74. When the first oil groove 70 is pulled, the first oil groove 70 slides relative to the groove accommodating portion 74a of the groove support member 74 and is removed from the groove support member 74.

[0097] In this manner, the first oil groove 70 can be removed in a pull-out direction Pd to one side in the longitudinal direction of the groove support member 74. In this embodiment, the first oil groove 70 is not fixed to the groove support member 74 by bolts, pins, or the like, and can therefore be removed from the groove support member 74 simply by pulling. Here, "removable" includes situations where the first oil groove 70 is fixed to the groove support member 74 by bolts, pins, or the like, and can be removed after removing these bolts, pins, or the like. Of course, it is preferable that the first oil groove 70 be designed to be removable from the groove support member 74 simply by pulling, as in this embodiment.

[0098] Furthermore, by pushing the first oil groove 70 pulled out of the groove support member 74 in the direction opposite to the withdrawal direction Pd, the first oil groove 70 can be pushed into the groove support member 74. In this way, the first oil groove 70 can be inserted and removed from the groove receiving portion 74a of the groove support member 74 along the longitudinal direction of the groove support member 74.

[0099] like Figure 8 As shown in Figures 11(a) and 11(b), the first oil groove 70 has a hanging portion 70c which is provided at a position different from the inner wall surface of the first groove portion 70a and can hook an object when the first oil groove 70 is pulled out from the groove support member 74. Here, the object refers to the operator's finger or tool, etc. The hanging portion 70c is provided at the end of the first oil groove 70 on the side of the pulling direction Pd. In detail, the first groove portion 70a has a vertical wall portion 70d which forms a lubricant storage chamber and rises from the bottom wall portion at the end on the side of the pulling direction Pd. The hanging portion 70c is in the shape of a plate extending from the upper end of the vertical wall portion 70d of the first groove portion 70a toward the pulling direction Pd. A hanging hole 70e for inserting an object is formed in the hanging portion 70c, and the object is hooked by inserting the object into the hanging hole 70e.

[0100] Next, the effects of the wheel drive device 10 will be described.

[0101] The wheel drive device 10 includes oil grooves 70 and 72 for catching the lubricant 60 leaking from the first oil seal 26. Therefore, the oil grooves 70 and 72 can prevent the lubricant leaking from the first oil seal 26 from falling to the ground, and can effectively deal with the leakage of the lubricant 60.

[0102] When loading and unloading the first oil tank 70, it is often difficult to ensure working space on both sides in the axial direction X of the wheel drive unit 10. This is because, in most cases, there is a vehicle body 12 on the vehicle body side closer to the wheel drive unit 10, and there is a structure on the side opposite to the vehicle body. In this example, the structure is a storage rack for transferring goods to and from a transport trolley. On the other hand, if it is a space on any side in the traveling direction Y of the wheel drive unit 10, it is easy to ensure the working space used when loading and unloading the first oil tank 70. In this embodiment, the first oil tank 70 can be pulled out in the traveling direction Y of the tire 14, that is, in the longitudinal direction of the tank support member 74. Therefore, the pulling operation of the first oil tank 70 is easy to perform and interference with the structures around the wheel drive unit 10 is avoided. In addition, there is the following advantage: the first oil tank 70 can be loaded and unloaded without disassembling the wheel drive unit 10.

[0103] The first oil tank 70 is held on the tank support member 74 by the magnetic force of the magnet 76. Therefore, the first oil tank 70 can be easily removed from the tank support member 74 or attached to the tank support member 74, and the first oil tank 70 can be prevented from falling off the tank support member 74 due to vibration during travel of the wheel drive device 10.

[0104] The inclined portion 74e of the tank support member 74 is inclined upward and outward in the longitudinal direction of the tank support member 74. Therefore, by strongly pulling the first oil tank 70, the first oil tank can be pulled out from the tank support member 74 while being guided by the inclined portion 74e of the tank support member 74.

[0105] The first oil tank 70 has a hook portion 70c for hooking an object when the first oil tank 70 is pulled out from the tank support member 74. Therefore, by hooking an object such as a finger on the hook portion 70c of the first oil tank 70, it is easy to apply a pulling force to the first oil tank 70, and the workability when pulling out the first oil tank 70 can be improved.

[0106] The oil grooves 70 and 72 include a first oil groove 70 and a second oil groove 72. Therefore, the oil grooves 70 and 72 can catch all the lubricant passing through the first gap 66 and the second gap 68, and the oil grooves 70 and 72 can handle leakage of the lubricant 60 in a wide range.

[0107] Furthermore, the second oil groove 72 is provided so as to guide the lubricant 60 into the first oil groove 70. Therefore, the lubricant 60 collected by the second oil groove 72 is also collected in the first oil groove 70. Therefore, when recovering the lubricant 60, only the lubricant in the first oil groove 70 needs to be recovered, which can reduce the man-hours required for the recovery operation.

[0108] The first oil groove 70 is configured below the vertical direction of the outer peripheral end portion 62c of the fling plate 62. Therefore, the lubricant flung off by the fling plate 62 can be caught by the first oil groove 70 and concentrated in the first oil groove 70.

[0109] A portion (both ends) of the first oil tank 70 is located below the outer circumferential surface of the outer cover portion 48a of the wheel cover 48. Therefore, compared to a case where the first oil tank 70 is located solely inside the wheel cover 48 or below the opening 48d, the state of the lubricant stored in the first oil tank 70 can be more easily observed from the outside with the naked eye. Consequently, it is possible to easily determine whether the lubricant in the first oil tank 70 needs to be recovered without removing the first oil tank 70 from the wheel drive device 10.

[0110] In addition, if Figure 10(a) to Figure 10(c)As shown, a downwardly recessed groove portion 74f is formed on the upper portion of the inner side wall portion 74c of the groove support member 74. The second groove portion 72a of the second oil groove 72 is disposed inside the groove recess 74f of the first groove portion 74, thereby preventing interference between the groove support member 74 and the second oil groove 72. Furthermore, a downwardly recessed slinger plate recess 74g is formed on the upper portion of the inner side wall portion 74c of the first groove portion 74. A portion of the curved portion 62b of the slinger plate 62 is disposed inside the slinger plate recess 74g of the first groove portion 74, thereby preventing interference between the groove support member 74 and the curved portion 62b of the slinger plate 62.

[0111] (Second embodiment)

[0112] Figure 12 This is a partial front cross-sectional view of the wheel drive device 10 according to the second embodiment. The wheel drive device 10 according to the second embodiment does not include the oil grooves 70 and 72 of the first embodiment. Furthermore, the wheel drive device 10 according to the second embodiment differs from the wheel drive device according to the first embodiment primarily in the slinger plate 62 and the lubricant absorber 78 described later.

[0113] The flinger 62 of the second embodiment does not have the curved portion 62b of the first embodiment. Instead, the outer peripheral end of the annular portion 62a serves as the outer peripheral end 62c of the flinger 62. The outer peripheral end 62c of the flinger 62 is positioned radially outward from the interface 64 between the tire 14 and the wheel hub 44. The outer peripheral end 62c of the flinger 62 of this embodiment is positioned radially inward from the contact surface 22b of the tire 14 that contacts the running surface 16a. As a result, the lubricant 60 is flung from the outer peripheral end 62c of the flinger 62 in the direction Pb at a position separated from the side surface 22a of the rotating body 22. In other words, in this embodiment, the lubricant 60 is also separated from the rotating body 22 before it reaches the contact surface 22b of the rotating body 22. Therefore, even if the lubricant 60 leaks, the adverse effects of the lubricant 60 flowing onto the contact surface 22b of the rotating body 22 can be prevented, effectively addressing the lubricant 60 leakage.

[0114] Figure 13 4 is a side cross-sectional view showing the circumferential end portion 48e of the wheel cover 48. Figure 12 and Figure 13 The lubricant absorber 78 is a component for absorbing lubricant 60 that leaks from the location where the first oil seal 26 is located. The lubricant absorber 78 includes a first lubricant absorber 78-A mounted on the rotating body 22 and a second lubricant absorber 78-B mounted on the wheel cover 48. The lubricant absorber 78 is made of a material that has the property of absorbing liquids. This material can be, for example, woven fabric or non-woven fabric.

[0115] The first lubricant absorber 78 is provided on the path where lubricant leaking from the location of the first oil seal 26 flows toward the outer surface of the rotating body 22. This path includes a joint 80 between the first oil seal 26 and the rotating body 22. In this embodiment, the first lubricant absorber 78 is provided to block this joint 80. Although not shown, the first lubricant absorber 78 is provided on both sides of the rotating body 22 in the axial direction X.

[0116] The position of the first lubricant absorber 78 relative to the rotating body 22 is maintained by the flinger plate 62. Specifically, the flinger plate 62 has, in addition to the annular portion 62a, a pressing portion 62d that bends from the inner peripheral end of the annular portion 62a toward the rotating body side. The first lubricant absorber 78 is sandwiched between the pressing portion 62d and the inner peripheral portion of the rotating body 22, thereby maintaining the position of the first lubricant absorber 78 relative to the rotating body 22. In this way, the flinger plate 62 is detachably fixed to the rotating body 22 and functions as a retaining component that maintains the position of the first lubricant absorber 78. Since the flinger plate 62 also has the function of the retaining component, when the flinger plate 62 is loaded and unloaded from the rotating body 22, the first lubricant absorber 78-A can also be loaded and unloaded from the rotating body 22. In addition, the retaining component can also be provided separately from the flinger plate 62.

[0117] The second lubricant absorber 78-B is located on the path through which the lubricant 60 adhering to the inner circumferential surface of the outer peripheral cover portion 48a of the wheel cover 48 flows. This path includes the upper surface of the inner flange portion 48f of the wheel cover 48. The second lubricant absorber 78-B of this embodiment is located above the upper surface of the inner flange portion 48f. The second lubricant absorber 78-B is located on the inner flange portion 48f of the wheel cover 48 and is sandwiched between the inner flange portion 48f and the head of the bolt B5, thereby maintaining the position of the second lubricant absorber 78-B relative to the wheel cover 48. The lubricant 60 adhering to the inner circumferential surface of the wheel cover 48 is the lubricant thrown off by the thrower plate 62 and is a portion of the lubricant 60 that leaked from the location where the first oil seal 26 is located. That is, both the first lubricant absorber 78 -A and the second lubricant absorber 78 -B absorb the lubricant 60 leaking from the location where the first oil seal 26 is disposed.

[0118] According to the wheel drive device 10 , even if the lubricant 60 leaks from the location where the first oil seal 26 is disposed, the lubricant absorber 78 absorbs the lubricant 60 and prevents the lubricant 60 from spreading to the surrounding area.

[0119] The embodiments of the present invention have been described in detail above. The above embodiments are merely specific examples for implementing the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of constituent elements can be made without departing from the scope of the idea of ​​the invention defined in the claims. In the above embodiments, the contents that can undergo such design changes are described by indicating terms such as "embodiment" and "in the implementation", but this does not mean that design changes are not allowed for contents that do not indicate these terms. In addition, the hatching lines marked on the cross sections in the accompanying drawings do not limit the material of the objects marked with hatching lines.

[0120] While the wheel drive device 10 is described above as being assembled on a transport vehicle, the assembly target is not particularly limited. Furthermore, while the transport vehicle is described above as being a track-guided vehicle, the transport vehicle may also be a trackless vehicle.

[0121] The above description describes an example of an eccentric oscillating type reduction mechanism. However, the type of reduction mechanism 20 is not particularly limited. For example, it may include a planetary gear mechanism, a parallel axis gear mechanism, an orthogonal axis gear reduction mechanism, a flexure meshing type reduction mechanism, and the like.

[0122] While the above description describes an example in which the eccentric body 32 and the input shaft 18 are separate components, the eccentric body 32 may also be provided as part of a single component identical to the input shaft 18. Furthermore, while the above description describes an example in which the first inner ring 36 c of the eccentric body bearing 36 is formed from a component separate from the eccentric body 32, the eccentric body bearing 36 may also be formed from a portion of the same component as the eccentric body 32. Furthermore, while the above description describes an example in which the first outer ring 36 d of the eccentric body bearing 36 is formed from a portion of the same component as the external gear 34, the eccentric body bearing 36 may also be formed from a component separate from the external gear 34.

[0123] While the above description uses an example in which hard lubricant 60-A uses a lubricant with a consistency grade of 2 and soft lubricant 60-B uses a lubricant with a consistency grade of 00, this is not limiting. For example, soft lubricant 60-B may use a lubricant with the same consistency grade as hard lubricant 60-A, but with a greater mixed consistency than that of hard lubricant 60-A. Furthermore, the consistency grades of the lubricants used for hard lubricant 60-A and soft lubricant 60-B are not particularly limited. In this case, soft lubricant 60-B may use a lubricant with a wider mixed consistency range than the mixed consistency range corresponding to the hard lubricant 60-A.

[0124] Furthermore, while the above description uses an example in which lubricant 60 includes two lubricants with different mixed viscosities, lubricant 60 may also include three or more lubricants. In other words, lubricant 60 only needs to include at least two lubricants with different mixed viscosities. Furthermore, while the above description uses lubricant 60 as grease, the type is not limited to this. For example, lubricating oil may be used as soft lubricant 60-B.

[0125] The above describes an example in which the hard lubricant 60-A is applied to both the eccentric bearing 36 and the main bearing 50 when the amount of lubricant 60 enclosed is set to less than 35% of the volume of the enclosed space. However, the hard lubricant 60-A may be applied to only one of them, or to other parts that require lubrication.

[0126] Furthermore, when the slinger plate 62 is used in combination with either or both of the oil grooves 70 and 72, the amount of lubricant 60 enclosed can be set to be greater than 35% of the volume of the enclosed space. Furthermore, while the above description uses the oil grooves 70 and 72 in combination with the slinger plate 62 as an example, the oil grooves 70 and 72 may also be used without the slinger plate 62.

[0127] While the above description describes an example in which the flinger plate 62 is fixed to the side surface 22a of the rotating body 22, the flinger plate 62 may be fixed to a path along which the lubricant 60 leaking from the location where the first oil seal 26 is disposed flows toward the outer surface of the rotating body 22. For example, the flinger plate 62 may be fixed to the outer periphery of the rotating body 22 in addition to the side surface 22a of the rotating body 22.

[0128] While the above description describes an example in which the first oil tank 70 can be removed from the tank support member 74 simply by pulling it out, the present invention is not limited to this. While the above description describes an example in which the pulling direction Pd of the tank support member 74 is the longitudinal direction of the tank support member 74, the present invention is not limited to this. For example, the pulling direction Pd of the tank support member 74 may be a vertical direction intersecting the longitudinal direction of the tank support member 74. Furthermore, the first oil tank 70 may be fixed to a fixing member such as the tank support member 74 or the wheel frame 24 using bolts or the like.

[0129] While the above description uses the example of a configuration in which the groove support member 74 includes the inclined portion 74e, the groove support member 74 may also be configured without the inclined portion 74e. Furthermore, when the first oil groove 70 is not fixed to the groove support member 74, the inclined portion 74e of the groove support member 74 not only guides the first oil groove 70 but also abuts against the first oil groove 70 to limit relative displacement of the first oil groove 70 in the longitudinal direction.

[0130] While the magnet 76 is mounted on the lower surface of the first oil tank 70 , the mounting position is not particularly limited. For example, the magnet 76 may be mounted elsewhere in the first oil tank 70 or on the tank support member 74 .

[0131] The hook portion 70c of the first oil groove 70 is not particularly limited in shape as long as it can hook an object. For example, a convex portion protruding from the first groove portion 70a to serve as a handle, or a concave portion provided on the outer wall of the first groove portion 70a and capable of hooking an object can be used.

[0132] In the above description, the example in which the channel support member 74 is fixed to the wheel cover 48 is described, but the channel support member 74 may be fixed to the wheel carrier 24. Furthermore, if there is another component integrated with the wheel carrier 24, the channel support member 74 may be fixed to the other integrated component.

[0133] While the above description describes an example in which the second oil groove 72 is configured such that the end 72c of the second groove portion 72a in the longitudinal direction is open outward in the longitudinal direction, thereby guiding the lubricant within the second oil groove 72 into the first oil groove 70, the specific structure is not particularly limited. For example, a through hole may be provided in the bottom wall portion of the end 72c of the second groove portion 72a to guide the lubricant through the through hole into the first oil groove 70.

[0134] Furthermore, the above description describes an example in which the second oil groove 72 is configured to guide the lubricant received by the second oil groove 72 to the first oil groove 70. Alternatively, the first oil groove 70 may be configured to guide the lubricant received by the first oil groove 70 to the second oil groove 72. In this case, to facilitate recovery of the lubricant 60 collected in the second oil groove 72, the second oil groove 72 may be supported by a groove support member 74 and removable from the groove support member 74.

[0135] The shapes of the first oil groove 70 and the second oil groove 72 are not particularly limited as long as they can receive the lubricant 60. Furthermore, the above description uses the example of using both the first oil groove 70 and the second oil groove 72, but only one of them may be used.

Claims

1. A wheel drive device, characterized in that: have: A reduction mechanism that reduces the speed of rotation transmitted from the driving source; a rotating body to which the rotation decelerated by the speed reduction mechanism is transmitted, and the rotating body is integrated with the tire; A fixed component supporting the rotating body so as to enable it to rotate freely; an oil seal disposed between the rotating body and the fixed member and sealing a space containing the speed reduction mechanism; and Lubricant is sealed in the sealed space sealed by the oil seal, The enclosed space is a space for accommodating the speed reduction mechanism. The lubricant includes at least two lubricants having different mixing consistencies, and the at least two lubricants are enclosed in the same enclosed space. The total amount of lubricants enclosed, including the at least two lubricants, is less than 35% of the volume of the enclosed space. The speed reduction mechanism comprises: an eccentric body; an external gear that swings through the eccentric body; and an eccentric body bearing disposed between the eccentric body and the external gear. The lubricant includes: a hard lubricant applied to the eccentric bearing; and a soft lubricant having a mixed consistency greater than that of the hard lubricant.

2. The wheel drive device according to claim 1, characterized in that: The total amount of the lubricant sealed is greater than or equal to 25% of the volume of the sealed space.

3. The wheel drive device according to claim 1 or 2, characterized in that: The main bearing is further provided, and is arranged between the rotating body and the fixed member at a position closer to the sealed space than the oil seal. The lubricant includes: a hard lubricant applied to the main bearing; and The soft lubricant has a mixed consistency greater than that of the hard lubricant.

4. A wheel drive device, characterized in that: have: A reduction mechanism that reduces the speed of rotation transmitted from the driving source; a rotating body to which the rotation decelerated by the speed reduction mechanism is transmitted, and the rotating body is integrated with the tire; A fixed component supporting the rotating body so as to enable it to rotate freely; an oil seal disposed between the rotating body and the fixed member and sealing a space containing the speed reduction mechanism; and Lubricant is sealed in the sealed space sealed by the oil seal, The wheel drive device further comprises: an oil groove for collecting lubricant leaking from a position where the oil seal is disposed; a tank support member integrated with the fixing member and supporting the oil tank, The oil tank and the tank support member are long strip members that are elongated along the running direction of the tire. The oil groove is configured to be extractable along the longitudinal direction of the groove support member.

5. The wheel drive device according to claim 4, characterized in that: The oil tank is supported by a member integrated with the fixing member.

6. The wheel drive device according to claim 4, characterized in that: The oil tank is held by the tank support member by the magnetic force of a magnet.

7. The wheel drive device according to claim 4, characterized in that: The trough support member has an inclined portion at an end portion in the longitudinal direction thereof, the inclined portion being inclined upward and outward in the longitudinal direction of the trough support member.

8. A wheel drive device, characterized in that: have: A reduction mechanism that reduces the speed of rotation transmitted from the driving source; a rotating body to which the rotation decelerated by the speed reduction mechanism is transmitted, and the rotating body is integrated with the tire; A fixed component supporting the rotating body so as to enable it to rotate freely; an oil seal disposed between the rotating body and the fixed member and sealing a space containing the speed reduction mechanism; and Lubricant is sealed in the sealed space sealed by the oil seal, The wheel drive device further includes an oil groove that receives lubricant leaking from a location where the oil seal is disposed. The oil tank comprises: a first oil groove extending along the traveling direction of the tire; and The second oil groove extends along the axial direction of the tire. The first oil groove and the second oil groove are arranged so that one oil groove can guide the received lubricant to the other oil groove.

9. The wheel drive device according to any one of claims 4 to 8, characterized in that: A flinger is further provided, which rotates integrally with the rotating body and flings off lubricant leaking from the location where the oil seal is arranged. The oil groove is arranged below the outer peripheral end of the flinger plate in the vertical direction.

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