Axle device

Abstract

This axle device is mounted on a vehicle body, and comprises: a transmission shaft that transmits rotational power from a drive source; a differential device including a gear that is rotated about an axis along the left-right direction of the vehicle body by the rotation of the transmission shaft; and a housing that houses the differential device, and stores lubricating oil for lubricating the differential device. The housing has a protrusion on an inner wall facing the outer periphery of the gear.

Description

axle device

[0001] This application claims priority from Japanese Patent Application No. 2023-110861, filed on July 5, 2023, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses a lubrication structure for a power transmission device that supplies lubricating oil stored in the bottom of a carrier to one of the bearings. A groove-shaped flow path is formed on the inner wall surface of the carrier, which supplies lubricating oil scooped up by a rotating pinion gear to one of the bearings. A protrusion is provided above the flow path to guide the scooped up lubricating oil to the one of the bearings. Meanwhile, an axle device including an axle that transmits power from the engine through the transmission to the wheels is known. The axle device includes a drive shaft that transmits rotational power from the engine, a differential device including a bevel gear that rotates around an axis along the left-right direction of the vehicle body due to rotation of the drive shaft, and a housing that accommodates the differential device and stores lubricating oil for lubricating the differential device.

[0003] JP 2014-145409 A

[0004] In an axle device, the rotation of the bevel gear can cause a difference in the height of the lubricating oil liquid surface (hereinafter also referred to as the "oil level") between the left and right sides. For example, the oil level on the tooth surface side of the bevel gear is higher than on the opposite side (back side) of the bevel gear. In this case, a difference in the cooling capacity of the left and right brakes occurs. For example, to eliminate this difference, the initial oil level may be determined by adjusting the oil level to the lower side. However, in this case, oil is wasted by the difference in the oil level between the left and right sides, which can increase oil costs and result in oil churning losses. Therefore, there is room for improvement in reducing the difference in the oil level between the left and right sides.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an axle assembly that can reduce the difference in oil level between the left and right wheels.

[0006] An axle device according to one embodiment of the present invention is an axle device mounted on a vehicle body, and comprises: a transmission shaft that transmits rotational power from a drive source; a differential device including a gear that rotates around an axis along the left-right direction of the vehicle body due to rotation of the transmission shaft; and a housing that accommodates the differential device and stores lubricating oil for lubricating the differential device, the housing having a protrusion on its inner wall facing the outer periphery of the gear.

[0007] According to the above aspect, the difference in oil level between the left and right sides can be reduced.

[0008] 3 is an enlarged view of a portion of FIG. 3 showing the protrusions on the inner wall of the housing according to the embodiment; FIG. 4 is a rear view of a cross section of the axle device according to the embodiment cut along a vertical plane passing through the center of the axle along the left-right direction of the vehicle body, showing the oil level when the vehicle is stopped; FIG. 5 is a top view of a cross section of the axle device according to the embodiment cut along a horizontal plane passing through the center of the axle along the left-right direction of the vehicle body, showing the rotation direction of the transmission shaft and the rotation direction of the gear; FIG. 6 is a rear view of a cross section of the axle device according to the embodiment cut along a vertical plane passing through the center of the axle along the left-right direction of the vehicle body, showing the protrusions on the inner wall of the housing according to the embodiment; FIG. 7 is an enlarged view of a portion of FIG. 3 showing the protrusions on the inner wall of the housing according to the embodiment; FIG. 8 is a rear view of a cross section of the axle device according to a comparative example cut along a vertical plane passing through the center of the axle along the left-right direction of the vehicle body, showing the oil level during rotation;

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the embodiment, an axle device mounted on a wheel loader (an example of a vehicle) will be described as an example of the axle device.

[0010] In the following description, expressions indicating relative or absolute arrangements, such as "parallel," "orthogonal," "center," and "coaxial," do not only mean such arrangements or states in the strict sense, but also include arrangements or states in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. In the drawings used in the following description, the scale of each component may be changed as appropriate to make each component recognizable.

[0011] 1 is a perspective view of a vehicle 100 equipped with an axle device 1 according to an embodiment. As shown in FIG. 1, the vehicle 100 includes a body 101, a work implement 102, a front traveling device 103, a rear traveling device 104, and a driver's cab 105.

[0012] Hereinafter, the forward direction (front of the vehicle body), backward direction (rear of the vehicle body), and vehicle width direction (left-right direction of the vehicle body) of the vehicle will be referred to as the "front of the vehicle (one side in the front-rear direction of the vehicle)," "rear of the vehicle (the other side in the front-rear direction of the vehicle)," and "vehicle width direction." The vehicle width direction may also be referred to as the "left side (one side in the vehicle width direction)" or the "right side (the other side in the vehicle width direction)." The right side of the forward direction of the vehicle will be referred to as the right side, and the left side of the forward direction of the vehicle will be referred to as the left side. The vehicle up-down direction (up-down direction of the vehicle body), above the vehicle (above the vehicle body), and below the vehicle (below the vehicle body) will be simply referred to as the "up-down direction," "up," and "down." In the illustrated example, the vehicle is placed on a horizontal plane (level ground). The vehicle up-down direction (up-down direction of the vehicle body), above the vehicle (above the vehicle body), and below the vehicle (below the vehicle body) of the vehicle correspond to the up-down direction (vertical direction), vertically upward, and vertically downward, respectively, when the vehicle is placed on a horizontal plane. In the following description, the left-hand elements may be suffixed with the symbol L, and the right-hand elements may be suffixed with the symbol R.

[0013] A driver's cab 105 is provided on the upper part of the vehicle body 101. For example, the driver's cab 105 is equipped with a seat for the driver of the vehicle 100, levers for various operations, pedals, and instruments.

[0014] The work implement 102 is a machine for excavating or transporting work objects such as earth and sand. The work implement 102 is provided at the front of the vehicle body 101. For example, the work implement 102 includes a boom, a bucket, a bell crank, a lift cylinder, a bucket cylinder, and the like.

[0015] The front traveling device 103 is provided on the front lower part of the vehicle body 101. The front traveling device 103 is configured to include front wheels that can rotate around the axis of the front axle 112. The rear traveling device 104 is provided on the rear lower part of the vehicle body 101. The rear traveling device 104 is configured to include rear wheels that can rotate around the axis of the rear axle 113.

[0016] The vehicle 100 further includes a drive source 110, a transmission 111, a front axle 112, and a rear axle 113. The drive source 110 is mounted on the rear of the vehicle body 101. For example, the drive source 110 is a diesel engine (an example of an engine). For example, the engine is provided with a fuel injection device that injects fuel into the engine cylinders, an engine tachometer that measures the engine speed, and the like.

[0017] The transmission 111 changes the speed of the driving force input to the input shaft and outputs it from the output shaft. The input shaft of the transmission 111 is connected to the engine. The output shaft of the transmission 111 is connected to the front axle 112 and the rear axle 113. The transmission 111 transmits the driving force of the engine to the front axle 112 and the rear axle 113.

[0018] The front axle 112 transmits the driving force output by the transmission 111 to the front traveling device 103. As a result, the front wheels of the front traveling device 103 rotate in the direction of arrow R1 (the forward rotation direction in the illustrated example). The rear axle 113 transmits the driving force output by the transmission 111 to the rear traveling device 104. As a result, the rear wheels of the rear traveling device 104 rotate in the direction of arrow R2 (the forward rotation direction in the illustrated example).

[0019] <Axle Device> Fig. 2 is a rear view of a cross section of the axle device 1 according to the embodiment cut along a vertical plane passing through the axle center AC along the left-right direction of the vehicle body, showing the oil level when the vehicle is stopped. Fig. 3 is a top view of a cross section of the axle device 1 according to the embodiment cut along a horizontal plane passing through the axle center AC along the left-right direction of the vehicle body, showing the rotation direction of the transmission shaft 2 and the rotation direction of the gears. Fig. 4 is a rear view of a cross section of the axle device 1 according to the embodiment cut along a vertical plane passing through the axle center AC along the left-right direction of the vehicle body, showing the protrusion 80 on the inner wall 61 of the housing 4. The lubricating oil 5 is not shown in Figs. 2 to 4 . Referring to Figs. 2 to 4 , the axle device 1 is provided on a vehicle body 101. The axle device 1 includes a transmission shaft 2 that transmits rotational power from a drive source 110, a differential device 3 including a gear that rotates around an axis along the left-right direction of the vehicle body as a result of rotation of the transmission shaft 2, and a housing 4 that accommodates the differential device 3 and stores lubricating oil 5 for lubricating the differential device 3. The front axle 112 and the rear axle 113 are one embodiment of the axle device 1.

[0020] <Transmission Shaft> The transmission shaft 2 extends along the longitudinal direction of the vehicle body. The transmission shaft 2 is disposed at a center BC in the transverse direction of the vehicle body (hereinafter also referred to as the "vehicle body transverse center line BC"). The transmission shaft 2 is connected to an output shaft of the transmission 111. The front end of the transmission shaft 2 is provided with teeth 10 (hereinafter also referred to as the "drive pinion gear 10") that mesh with a bevel gear 20 (an example of a bevel gear that rotates around an axis along the transverse direction of the vehicle body as the transmission shaft 2 rotates).

[0021] <Differential Gear> The differential gear 3 includes a bevel gear 20, axle shafts 30L, 30R, side gears 31L, 31R, differential pinion shaft 40, differential pinion gears 41A, 41B, 41C, 41D, and bearings 50L, 50R. The bevel gear 20 is disposed offset to one side in the left-right direction of the vehicle body with respect to a center BC in the left-right direction of the vehicle body. In the example shown in the figure, the bevel gear 20 is disposed offset to the right with respect to the center BC in the left-right direction of the vehicle body. Note that the arrangement of the bevel gear 20 is not limited to the above and can be changed according to design specifications.

[0022] The bevel gear 20 includes a tooth surface portion 21 having teeth that mesh with the drive pinion gear 10, a back surface portion 22 that is located on the opposite side of the tooth surface portion 21 in the left-right direction of the vehicle body, and a side surface portion 23 that is located on the radially outer side of the bevel gear 20 and connects the tooth surface portion 21 and the back surface portion 22. For example, the portion of the tooth surface portion 21 opposite the side on which the teeth are provided (the tooth surface side) (the back surface side portion) is fixed to a differential case 24 (described later) by a fastening member such as a bolt. In the example shown in the figure, a bolt head 25 is located on the right side of a case back surface portion 27 of the differential case 24.

[0023] The differential case 24 includes a cylindrical right half 24R that opens in the left-right direction of the vehicle body and supports a portion of the right axle shaft 30R, and a cylindrical left half 24L that opens in the left-right direction of the vehicle body and supports a portion of the left axle shaft 30L. The differential case 24 is connected to the rear surface 22 of the bevel gear 20 and supports a portion of the axle shafts 30L, 30R. The outer periphery of the right half 24R is connected to the rear surface 22 of the bevel gear 20. For example, the left and right halves 24L, 24R are fixed to each other with fastening members 26 such as bolts.

[0024] The axle shafts 30L, 30R extend in the left-right direction of the vehicle body. The axle shafts 30L, 30R are provided as a pair on the left and right. The left and right axle shafts 30L, 30R are arranged coaxially with each other.

[0025] A pair of side gears 31L, 31R are provided on the left and right sides. The side gears 31L, 31R are connected to the inner ends of the axle shafts 30L, 30R in the vehicle width direction. The right axle shaft 30R is supported by the right half body 24R via the right side gear 31R. The left axle shaft 30L is supported by the left half body 24L via the left side gear 31L.

[0026] The differential pinion shaft 40 extends in four directions perpendicular to one another in the radial direction about the axle center AC. The differential pinion shaft 40 is positioned offset to the right with respect to the vehicle body left-right center line BC. The differential pinion shaft 40 extends forward-rearward, rearward, upward, and downward about the axle center AC. The portions of the differential pinion shaft 40 that extend forward and rearward, and the portions that extend upward and downward, are each positioned coaxially.

[0027] The differential pinion gears 41A, 41B, 41C, and 41D are supported on the differential pinion shaft 40 so as to be rotatable about the differential pinion shaft 40. The differential pinion gears 41A, 41B, 41C, and 41D are supported on portions of the differential pinion shaft 40 that extend forward, rearward, upward, and downward, respectively. The differential pinion gears 41A, 41B, 41C, and 41D mesh with the side gears 31L and 31R.

[0028] A pair of bearings 50L, 50R are provided on the left and right sides. The bearings 50L, 50R are arranged between the differential case 24 and the housing 4. The bearings 50L, 50R rotatably support the differential case 24 to which the bevel gear 20 is connected. The right bearing 50R is arranged between the outer periphery of the right half body 24R and the right inner periphery of the housing 4. The left bearing 50L is arranged between the outer periphery of the left half body 24L and the left inner periphery of the housing 4.

[0029] For example, when the transmission shaft 2 rotates in the direction of arrow J1 (the forward rotation direction in the illustrated example), the bevel gear 20 rotates in the direction of arrow J2 (the forward rotation direction in the illustrated example). Then, the side gears 31L, 31R and the axle shafts 30L, 30R rotate integrally with the rotation of the bevel gear 20. For example, when the vehicle 100 is traveling straight and there is no speed difference (difference in rotational speed) between the left and right wheels, the left and right side gears 31L, 31R and the axle shafts 30L, 30R rotate at the same speed.

[0030] On the other hand, when a load is applied to one of the left and right side gears 31L, 31R (for example, when one is fixed), the differential pinion gears 41A, 41B, 41C, 41D rotate while causing the other side gear 31L, 31R to rotate excessively. For example, when a speed difference (difference in rotation speed) occurs between the left and right wheels when the vehicle 100 turns a corner, this speed difference can be absorbed.

[0031] <Housing> The housing 4 is a front housing located at the front side in the longitudinal direction of the vehicle body. The housing 4 is formed in a cylindrical shape along the left-right direction of the vehicle body. An internal space 60 that houses the differential device 3 is formed in the housing 4. The portion of the housing 4 that houses the bevel gear 20 bulges outward in the radial direction more than the portion that houses the axle shafts 30L, 30R. In a cross-sectional view of the figure, an inner wall 61 of the portion of the housing 4 that houses the bevel gear 20 is curved toward the front.

[0032] As shown in Figure 2, lubricating oil 5 is stored in the internal space 60 of the housing 4. In the illustrated example, the initial liquid level S1 of the lubricating oil 5 before the bevel gear 20 rotates (hereinafter also referred to as the "initial oil level S1") is located along the central axes of the axle shafts 30L, 30R. In the illustrated example, the initial oil level S1 is located between the upper edges of the axle shafts 30L, 30R and the axle center AC. Note that the initial oil level S1 is not limited to the above and can be changed according to design specifications.

[0033] 2 and 3 , the axle device 1 further includes shrouds 65, 66 that guide the lubricating oil 5 that flows around the bevel gear 20 due to the rotation of the bevel gear 20. The shrouds 65, 66 are arranged with a gap between them and the inner wall 61 of the housing 4. The shrouds 65, 66 are configured to include plate-shaped portions that are aligned with the rotation direction of the bevel gear 20.

[0034] In the illustrated example, a pair of shrouds 65, 66 are provided via the bevel gear 20. The pair of shrouds 65, 66 includes a tooth surface side shroud 65 arranged with a gap between it and the tooth surface portion 21 of the bevel gear 20, and a back surface side shroud 66 arranged with a gap between it and the case back surface portion 27 of the differential case 24. Note that the configuration of the shrouds 65, 66 is not limited to the above and can be changed according to design specifications.

[0035] <Brakes> The axle device 1 further includes wet multi-plate brakes 70L, 70R at the outer ends in the left-right direction of the vehicle body. A pair of brakes 70L, 70R are provided on the left and right sides. The brakes 70L, 70R are disposed between the outer ends in the vehicle width direction of the axle shafts 30L, 30R and the final gears 71L, 71R. For example, the rotation of the engine, which is shifted by the transmission 111, is finally reduced in speed by the final gears 71L, 71R and transmitted to the tires.

[0036] At least a portion of the brakes 70L, 70R is immersed in the lubricating oil 5. For example, at the initial oil level S1, approximately half of the brakes 70L, 70R may be immersed in the lubricating oil 5. The manner in which the brakes 70L, 70R are immersed in the lubricating oil 5 is not limited to the above and can be changed according to design specifications.

[0037] <Protrusion> Fig. 5 is a diagram showing the protrusion 80 on the inner wall 61 of the housing 4 according to the embodiment, and is an enlarged view of a portion of Fig. 3. Fig. 6 is a perspective view showing the protrusion 80 on the inner wall 61 of the housing 4 according to the embodiment. In Fig. 6, the inner wall 61 (front inner wall 61) of the housing 4 on which the protrusion 80 is provided is not shown. Referring to Figs. 5 and 6 together, the housing 4 includes the protrusion 80 on the inner wall 61 that faces the outer periphery of the bevel gear 20. The protrusion 80 is provided on the front inner wall 61 of the front housing.

[0038] The protrusion 80 protrudes from the front inner wall 61 of the housing 4 toward the outer periphery of the bevel gear 20. For example, the protrusion 80 may be formed integrally with the front inner wall 61 of the housing 4 using the same member. In this case, for example, the protrusion 80 may be a raised portion that protrudes from a part of the housing 4. Note that the protrusion 80 is not limited to being a raised portion, and may be formed using a member (a plate-shaped member) different from the front inner wall 61 of the housing 4. In this case, for example, the plate-shaped member that forms the protrusion 80 may be fixed to the front inner wall 61 of the housing 4 by welding or the like. For example, the form of the protrusion 80 is not limited to the above and can be changed according to design specifications.

[0039] 4 and 5 , when viewed from the front-rear direction of the vehicle body, a portion of the outer shape of the protrusion 80 overlaps with the center BC in the left-right direction of the vehicle body. In the example shown, when viewed from the front-rear direction of the vehicle body, a portion of the outer shape of the protrusion 80 overlaps with the outer end of the bevel gear 20 in the left-right direction of the vehicle body. In the example shown, when the vehicle body 101 is tilted forward by 6 degrees downward in the front-rear direction of the vehicle body, a portion of the outer shape of the protrusion 80 overlaps with the liquid level S2 of the lubricating oil 5 (hereinafter also referred to as the "oil level S2 when tilted forward"). The oil level S2 when tilted forward is located higher on the vehicle body than the initial oil level S1.

[0040] 2 and 3 , when viewed from the front-rear direction of the vehicle body, a portion of the protrusion 80 overlaps with the transmission shaft 2. At least a portion of the protrusion 80 is immersed in the lubricating oil 5. For example, at the initial oil level S1, approximately half of the protrusion 80 may be immersed in the lubricating oil 5. Note that the manner in which the protrusion 80 is immersed in the lubricating oil 5 is not limited to the above and can be changed according to design specifications.

[0041] 5 and 6 , the size of the gap G between the protrusion 80 and the bevel gear 20 is 5 mm or more and 10 mm or less. The gap G between the protrusion 80 and the bevel gear 20 corresponds to the minimum distance between the protrusion 80 and the bevel gear 20. In the example shown in the figures, a recess 81 is formed in the portion of the protrusion 80 that faces the side surface 23 of the bevel gear 20. For example, the bottom surface of the recess 81 is disposed with a uniform gap G along the side surface 23 of the bevel gear 20 in the rotational direction and axial direction of the bevel gear 20.

[0042] 3 and 4 , when viewed from the front-rear direction of the vehicle body, a portion of the outer shape of the protrusion 80 is inclined so as to approach the axle center AC from the tooth surface side toward the back surface side of the bevel gear 20. The axle center AC corresponds to the centers of the axle shafts 30L, 30R.

[0043] When viewed from the front-rear direction of the vehicle body, at least a part of the outline of the protrusion 80 overlaps with the outline of a triangle that includes two sides V1, V2 that incline from the upper and lower sides in the vertical direction of the vehicle body toward the axle center AC as they move from the tooth surface side to the back surface side of the bevel gear 20, and one side V3 that extends along the vehicle body lateral center line BC. In the example shown in the figure, when viewed from the front-rear direction of the vehicle body, a part of the outline of the protrusion 80 overlaps with the outline of an equilateral triangle with one vertex on the axle center AC.

[0044] 4 and 5 , when viewed from the vehicle front-rear direction, a portion of the outer shape of the protrusion 80 overlaps with the shroud 65. In the example shown in the figures, when viewed from the vehicle front-rear direction, a portion of the outer shape of the protrusion 80 overlaps with the tooth surface side shroud 65. In the example shown in the figures, a groove 82 is formed in the portion of the protrusion 80 that overlaps with the tooth surface side shroud 65 when viewed from the vehicle front-rear direction.

[0045] On the other hand, the outer shape of the projection 80 does not overlap with the rear shroud 66 when viewed from the front-rear direction of the vehicle body. In the example shown in the figure, the right end of the projection 80 is located more inward in the left-right direction of the vehicle body than the rear shroud 66. For example, a notch may be formed in the right end of the projection 80 to provide a predetermined distance from the rear shroud 66. For example, the right end of the projection 80 may be set at a position that overlaps with the head 25 of a bolt located on the right side of the case rear portion 27 when viewed from the front-rear direction of the vehicle body.

[0046] For example, if a portion of the contour of the protrusion 80 overlaps with the contour of the equilateral triangle as viewed from the vehicle front-rear direction, the contour of the protrusion 80 may be set by the following steps (1) to (6): (1) The right end of the protrusion 80 is set to a position overlapping with the head 25 of the bolt located on the right side of the case rear portion 27 as viewed from the vehicle front-rear direction. (2) The left end of the protrusion 80 is set to a position overlapping with the center BC in the vehicle left-right direction as viewed from the vehicle front-rear direction. (3) A portion of the edge V1 of the contour of the protrusion 80, which slopes from the upper side in the vehicle vertical direction toward the axle center AC as it moves from the tooth surface side to the rear side of the bevel gear 20, is set to a position overlapping with the oil level S2 when the vehicle is tilted forward. (4) As viewed from the vehicle front-rear direction, the angle between the edge V3 (edge ​​extending in the vehicle vertical direction) along the left end of the protrusion 80 in (2) above and the edge V1 in (3) above is set to 60 degrees. (5) When viewed from the longitudinal direction of the vehicle body, side V2 of the contour of the protrusion 80, which slopes from the lower side in the vertical direction of the vehicle body toward the axle center AC as it moves from the tooth surface side to the back surface side of the bevel gear 20, is set at a position that is linearly symmetrical with side V1 of (4) above, with the axle center AC as the axis of symmetry. (6) The portion of the protrusion 80 that faces the side surface portion 23 of the bevel gear 20 is spaced from the side surface portion 23 of the bevel gear 20 by a gap G of about 10 mm. Note that the procedure for setting the contour of the protrusion 80 is not limited to the above and can be changed according to the design specifications.

[0047] <Operation and Effect> As described above, the axle device 1 of this embodiment is provided on the vehicle body 101. The axle device 1 includes a transmission shaft 2 that transmits rotational power from a drive source 110, a differential device 3 including a bevel gear 20 that rotates about an axis along the left-right direction of the vehicle body due to rotation of the transmission shaft 2, and a housing 4 that accommodates the differential device 3 and stores lubricating oil 5 for lubricating the differential device 3. The housing 4 includes a protrusion 80 on an inner wall 61 that faces the outer periphery of the bevel gear 20. For example, as shown in FIG. 7 , in the axle device 1X, rotation of the bevel gear 20X may cause a difference in the liquid level (oil level) of the lubricating oil 5 between the left and right sides. For example, the oil level on the tooth surface side of the bevel gear 20X is higher than on the side opposite the tooth surface (back side) of the bevel gear 20X. In this case, a difference in cooling capacity between the left and right brakes occurs. For example, to eliminate this difference, the initial oil level may be determined by adjusting the oil level to the lower side. However, in this case, oil is wasted due to the difference in oil level between the left and right sides, which can increase oil costs and result in oil churning loss. In contrast, according to the present configuration, by providing a protrusion 80 on the inner wall 61 of the housing 4 facing the outer periphery of the bevel gear 20, the protrusion 80 can narrow the gap G between the inner wall 61 of the housing 4 and the outer periphery of the bevel gear 20. Therefore, the flow rate of oil flowing around the bevel gear 20 due to the rotation of the bevel gear 20 can be increased by the throttling effect of the protrusion 80. This increases the flow rate of oil flowing toward the back side of the bevel gear 20 rather than the tooth surface side (e.g., oil flowing in the direction of the arrow in Figure 6). Therefore, the rotation of the bevel gear 20 can increase the flow rate of oil flowing from the side with a higher oil level to the side with a lower oil level. Therefore, the difference in oil level between the left and right sides can be reduced.

[0048] In this embodiment, when viewed from the front-rear direction of the vehicle body, a portion of the outer shape of the protrusion 80 overlaps with the center BC in the left-right direction of the vehicle body. For example, if the outer shape of the protrusion 80 extends too far in the direction of the tooth surface of the bevel gear 20 relative to the center BC in the left-right direction of the vehicle body when viewed from the front-rear direction of the vehicle body, this will hinder the flow of oil from the tooth surface side to the back surface side of the bevel gear 20. In contrast, with this configuration, when viewed from the front-rear direction of the vehicle body, a portion of the outer shape of the protrusion 80 overlaps with the center BC in the left-right direction of the vehicle body, thereby making it possible to avoid a situation in which the flow of oil is hindered from the tooth surface side to the back surface side of the bevel gear 20.

[0049] In this embodiment, when viewed from the front-rear direction of the vehicle body, a part of the outer shape of the protrusion 80 overlaps with the outer end of the bevel gear 20 in the left-right direction of the vehicle body. This configuration makes it possible to prevent the outer shape of the protrusion 80 from becoming larger than necessary.

[0050] In this embodiment, when the vehicle body 101 is tilted forward by 6 degrees downward in the front-to-rear direction of the vehicle body, a portion of the outer shape of the protrusion 80 overlaps with the liquid surface S2 of the lubricating oil 5. With this configuration, even when the vehicle body 101 is tilted forward by 6 degrees downward in the front-to-rear direction of the vehicle body, the flow rate of the oil flowing around the bevel gear 20 due to the rotation of the bevel gear 20 can be increased by the throttling effect of the protrusion 80. For example, even when the vehicle 100 is traveling downhill, the difference in oil level between the left and right sides can be reduced.

[0051] In this embodiment, when viewed from the front-rear direction of the vehicle body, a portion of the protrusion 80 overlaps with the transmission shaft 2. With this configuration, the flow rate of oil flowing around the bevel gear 20 due to the rotation of the bevel gear 20 accompanying the rotation of the transmission shaft 2 can be more effectively increased by the throttling effect of the protrusion 80.

[0052] In this embodiment, the housing 4 is a front housing located at the front side in the longitudinal direction of the vehicle body. The protrusion 80 is provided on the front inner wall 61 of the front housing. This configuration can reduce the difference in oil level between the left and right sides in the internal space 60 of the front housing.

[0053] In this embodiment, at least a portion of the protrusion 80 is immersed in the lubricating oil 5. With this configuration, the flow rate of the oil flowing around the bevel gear 20 due to the rotation of the bevel gear 20 can be more effectively increased by the throttling effect of the protrusion 80.

[0054] In this embodiment, the size of the gap G between the protrusion 80 and the bevel gear 20 is 5 mm or more and 10 mm or less. For example, if the size of the gap G between the protrusion 80 and the bevel gear 20 is less than 5 mm, the gap G will be too small, and it is highly likely that the necessary dimension cannot be secured, taking into account rotational variations of the bevel gear 20, manufacturing variations of the housing 4, adjustment margins during assembly of the differential device 3, and the like. On the other hand, if the size of the gap G between the protrusion 80 and the bevel gear 20 exceeds 10 mm, it is highly likely that the throttling effect of the protrusion 80 cannot be fully obtained. In contrast, according to the present configuration, by setting the size of the gap G between the protrusion 80 and the bevel gear 20 to 5 mm or more and 10 mm or less, it is possible to secure the above-mentioned necessary dimension while fully obtaining the throttling effect of the protrusion 80.

[0055] In this embodiment, when viewed from the front-to-rear direction of the vehicle body, part of the outer shape of the protrusion 80 is inclined so as to approach the axle center AC as it moves from the tooth surface side to the back surface side of the bevel gear 20. With this configuration, compared to when the outer shape of the protrusion 80 extends uniformly in the left-to-right direction of the vehicle body from the tooth surface side to the back surface side of the bevel gear 20, oil that flows around the bevel gear 20 as the bevel gear 20 rotates can be more easily guided from the tooth surface side to the back surface side of the bevel gear 20. Therefore, the difference in oil level between the left and right sides can be more effectively reduced.

[0056] In this embodiment, when viewed from the front-rear direction of the vehicle body, at least a portion of the contour of the protrusion 80 overlaps with the contour of a triangle including two sides V1 and V2 that slope from the upper and lower sides of the vehicle in the vertical direction toward the axle center AC as they extend from the tooth surface side toward the back surface side of the bevel gear 20, and one side V3 that extends along the vehicle body lateral center line BC. This configuration facilitates guiding oil flowing around the bevel gear 20 from the tooth surface side toward the back surface side of the bevel gear 20 as the bevel gear 20 rotates forward and backward. This makes it possible to more effectively reduce the difference in oil level between the left and right sides. For example, this makes it possible to more effectively reduce the difference in oil level between the left and right sides when the vehicle 100 is traveling forward and backward.

[0057] In this embodiment, the axle device 1 further includes a shroud 65 that guides the lubricating oil 5 that flows around the bevel gear 20 as the bevel gear 20 rotates. When viewed from the front-to-rear direction of the vehicle body, a portion of the outer shape of the protrusion 80 overlaps with the shroud 65. With this configuration, the throttling effect of the protrusion 80 can more effectively increase the flow rate of the oil that flows around the bevel gear 20 as the bevel gear 20 rotates and is guided by the shroud 65.

[0058] In this embodiment, the axle device 1 further includes wet multi-plate brakes 70L, 70R at the outer ends in the left-right direction of the vehicle body. At least a portion of the brakes 70L, 70R is immersed in the lubricating oil 5. With this configuration, the brakes 70L, 70R can be cooled by the lubricating oil 5, thereby maintaining the braking performance of the brakes 70L, 70R.

[0059] <Modifications> In the above-described embodiment, an example has been described in which a portion of the outer shape of the protrusion overlaps with the center of the vehicle body in the left-right direction when viewed from the front-rear direction of the vehicle body, but this is not limited to this. For example, the entire outer shape of the protrusion does not have to overlap with the center of the vehicle body in the left-right direction when viewed from the front-rear direction of the vehicle body. For example, the outer shape of the protrusion may extend elongatedly in the direction of the tooth surface of the bevel gear relative to the center of the vehicle body in the left-right direction when viewed from the front-rear direction of the vehicle body. For example, the arrangement of the outer shape of the protrusion relative to the center of the vehicle body in the left-right direction can be changed according to design specifications.

[0060] In the above-described embodiment, an example has been described in which a portion of the outer shape of the protrusion overlaps with the outer end of the bevel gear in the vehicle left-right direction when viewed from the vehicle front-rear direction, but this is not limited to this. For example, the entire outer shape of the protrusion does not have to overlap with the outer end of the bevel gear in the vehicle left-right direction when viewed from the vehicle front-rear direction. For example, the arrangement of the outer shape of the protrusion relative to the outer end of the bevel gear in the vehicle left-right direction can be changed depending on the design specifications.

[0061] In the above-described embodiment, an example has been described in which a portion of the outer shape of the protrusion overlaps with the lubricating oil level when the vehicle body is tilted forward by 6 degrees downward relative to the vehicle body longitudinal direction, but this is not limited to this. For example, when the vehicle body is tilted forward by 6 degrees downward relative to the vehicle body longitudinal direction, the entire outer shape of the protrusion does not have to overlap with the lubricating oil level. For example, the arrangement of the outer shape of the protrusion relative to the lubricating oil level when the vehicle body is tilted forward can be changed according to design specifications.

[0062] In the above-described embodiment, an example has been described in which a portion of the protrusion overlaps with the transmission shaft when viewed from the front-rear direction of the vehicle body, but this is not limiting. For example, the entire protrusion does not need to overlap with the transmission shaft when viewed from the front-rear direction of the vehicle body. For example, the arrangement of the outer shape of the protrusion relative to the transmission shaft can be changed according to design specifications.

[0063] In the above-described embodiment, the housing is a front housing disposed at the front side in the longitudinal direction of the vehicle body, and the protrusion is provided on the front inner wall of the front housing. However, this is not limited to this. For example, the housing may be a rear housing disposed at the rear side in the longitudinal direction of the vehicle body, and the protrusion may be provided on the rear inner wall of the rear housing. For example, the protrusion may be provided on the front inner wall of the front housing and / or the rear inner wall of the rear housing. For example, the manner in which the protrusion is provided on the front housing and the rear housing can be changed depending on the design specifications.

[0064] In the above-described embodiment, an example has been described in which at least a portion of the protrusion is immersed in the lubricating oil, but this is not limiting. For example, the entire protrusion does not need to be immersed in the lubricating oil. For example, the manner in which the protrusion is immersed in the lubricating oil can be changed depending on the design specifications.

[0065] In the above-described embodiment, the size of the gap between the protrusion and the bevel gear is described as being 5 mm or more and 10 mm or less, but this is not limiting. For example, the size of the gap between the protrusion and the bevel gear may be less than 5 mm or more than 10 mm. For example, the size of the gap between the protrusion and the bevel gear can be changed according to design specifications.

[0066] In the above-described embodiment, an example was given in which a portion of the outer shape of the protrusion is inclined toward the axle center as it moves from the tooth surface side to the back surface side of the bevel gear when viewed from the front-rear direction of the vehicle body, but this is not limited thereto. For example, the outer shape of the protrusion may extend uniformly in the left-right direction of the vehicle body from the tooth surface side to the back surface side of the bevel gear. For example, the inclination of the outer shape of the protrusion relative to the axle center can be changed according to design specifications.

[0067] In the above-described embodiment, an example was given in which at least a portion of the outer shape of the protrusion, as viewed from the longitudinal direction of the vehicle body, overlaps with the outer shape of a triangle including two sides that incline from the upper and lower sides of the vehicle body in the vertical direction toward the axle center as they move from the tooth surface side to the back surface side of the bevel gear, and one side that extends along the lateral center line of the vehicle body. However, this is not limited to this. For example, as viewed from the longitudinal direction of the vehicle body, the entire outer shape of the protrusion does not have to overlap with the above-described triangle. For example, as viewed from the longitudinal direction of the vehicle body, the outer shape of the protrusion may be a polygon such as a rectangle or a pentagon, a curved shape such as a circle, an ellipse, or an oval, a shape including straight lines and curves, or a shape that is a combination of these. For example, the outer shape of the protrusion may be changed according to design specifications.

[0068] In the above-described embodiment, the axle device further includes a shroud that guides lubricating oil that flows around the bevel gear as the bevel gear rotates, and an example has been described in which a portion of the outer shape of the protrusion overlaps with the shroud when viewed from the longitudinal direction of the vehicle body. However, this is not limited to this. For example, the entire outer shape of the protrusion does not need to overlap with the shroud when viewed from the longitudinal direction of the vehicle body. For example, the axle device does not need to include a shroud. For example, the arrangement of the outer shape of the protrusion relative to the shroud and / or the installation of the shroud can be changed according to design specifications.

[0069] In the above-described embodiment, the axle device further includes a wet multi-plate brake on the outer end side in the left-right direction of the vehicle body, and at least a portion of the brake is immersed in lubricating oil. However, this is not limited to this. For example, the entire brake does not have to be immersed in lubricating oil. For example, at least a portion of the brake may be immersed in oil other than the above-described lubricating oil. For example, the axle device may not include the above-described brake. For example, the axle device may include a brake other than a wet multi-plate brake. For example, the manner in which the brake is immersed in lubricating oil and / or the manner in which the brake is installed can be changed according to design specifications.

[0070] In the above-described embodiment, the axle device transmits power from a diesel engine, which is a drive source, through a transmission to the wheels. However, this is not limiting. For example, the drive source may be an engine other than a diesel engine. For example, the axle device may transmit rotational power from a power source other than an engine to the wheels. For example, the type of drive source may be changed depending on the design specifications.

[0071] In the above-described embodiment, the axle device is described as being mounted on a wheel loader, but this is not limiting. For example, the axle device may be mounted on other work vehicles such as an excavator, a bulldozer, or a dump truck. For example, the type of vehicle on which the axle device is mounted can be changed depending on the design specifications.

[0072] In the above-described embodiment, the gear that rotates about an axis along the left-right direction of the vehicle body due to the rotation of the transmission shaft is a bevel gear, but this is not limited to this. For example, the gear that rotates about an axis along the left-right direction of the vehicle body due to the rotation of the transmission shaft may be configured to include other gears such as a spur gear, a helical gear, a screw gear, a double-helical gear, or a spherical gear. For example, the configuration of the gear that rotates about an axis along the left-right direction of the vehicle body due to the rotation of the transmission shaft can be changed depending on the design specifications.

[0073] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and additions, omissions, substitutions, and other modifications to the configuration are possible within the scope of the spirit of the present invention, and the above-described embodiments can also be combined as appropriate.

[0074] (Supplementary Note 1) An axle device provided on a vehicle body, comprising: a transmission shaft that transmits rotational power from a drive source; a differential device including a gear that rotates around an axis along the left-right direction of the vehicle body due to rotation of the transmission shaft; and a housing that accommodates the differential device and stores lubricating oil for lubricating the differential device, wherein the housing has a protrusion on an inner wall that faces the outer periphery of the gear.

[0075] (Supplementary Note 2) The axle device according to Supplementary Note 1, wherein a part of the outer shape of the protrusion overlaps with the center of the vehicle body in the left-right direction when viewed from the front-rear direction of the vehicle body.

[0076] (Supplementary Note 3) The axle device according to Supplementary Note 2, wherein a part of an outer shape of the protrusion overlaps with an outer end of the gear in the left-right direction of the vehicle body when viewed from the front-rear direction of the vehicle body.

[0077] (Supplementary Note 4) The axle device according to Supplementary Note 3, wherein when the vehicle body is tilted forward by 6 degrees downwardly toward the front with respect to the longitudinal direction of the vehicle body, a part of the outer shape of the protrusion overlaps with the liquid surface of the lubricating oil.

[0078] (Supplementary Note 5) The axle device according to any one of Supplementary Notes 1 to 4, wherein a portion of the protrusion overlaps with the transmission shaft when viewed from the front-rear direction of the vehicle body.

[0079] (Appendix 6) An axle device according to any one of Appendices 1 to 5, wherein the housing is a front housing arranged at the front side in the fore-and-aft direction of the vehicle body, or a rear housing arranged at the rear side in the fore-and-aft direction of the vehicle body, and the protrusion is provided on a front inner wall of the front housing or a rear inner wall of the rear housing.

[0080] (Supplementary Note 7) The axle device according to any one of Supplementary Notes 1 to 6, wherein at least a portion of the protrusion is immersed in the lubricating oil.

[0081] (Supplementary Note 8) The axle device according to any one of Supplementary Notes 1 to 7, wherein the size of the gap between the protrusion and the gear is 5 mm or more and 10 mm or less.

[0082] (Supplementary Note 9) The axle device according to any one of Supplementary Notes 1 to 8, wherein, when viewed from the front-rear direction of the vehicle body, a part of the outer shape of the protrusion is inclined so as to approach the center of the axle as it goes from the tooth surface side of the gear to the back surface side.

[0083] (Appendix 10) An axle device as described in Appendix 9, wherein, when viewed from the fore-and-aft direction of the vehicle body, at least a portion of the outer shape of the protrusion overlaps with the outer shape of a triangle including two sides that incline from the upper and lower sides in the vertical direction of the vehicle body so as to approach the center of the axle as they move from the tooth surface side to the back side of the gear, and one side that follows the left-right center line of the vehicle body.

[0084] (Supplementary Note 11) The axle device according to any one of Supplementary Notes 1 to 10, further comprising a shroud that guides the lubricating oil that flows around the gear as the gear rotates, and when viewed from the fore-and-aft direction of the vehicle body, a portion of the outer shape of the protrusion overlaps with the shroud.

[0085] (Supplementary Note 12) The axle device according to any one of Supplementary Notes 1 to 11, further comprising a wet multi-plate brake on an outer end side in the left-right direction of the vehicle body, at least a portion of the brake being immersed in the lubricating oil.

[0086] According to the above embodiment, the difference in oil level between the left and right sides can be reduced.

[0087] 1...Axle device, 2...Transmission shaft, 3...Differential device, 4...Housing, 5...Lubricant, 20...Bevel gear (gear that rotates around an axis along the left-right direction of the vehicle body due to rotation of the transmission shaft), 25...Bolt head (outer end of gear in the left-right direction of the vehicle body), 61...Inner wall, 65...Tooth surface side shroud (shroud), 70L, 70R...Brake, 80...Protrusion, 101...Vehicle body, 110...Drive source, AC...Axle center, BC...Vehicle body left-right center line (center in the left-right direction of the vehicle body), G...Gap between protrusion and gear, S1, S2...Lubricant level, V1, V2, V3...Sides included in the outer shape of the triangle

Claims

1. An axle device provided on a vehicle body, comprising: a transmission shaft that transmits rotational power from a drive source; a differential device including a gear that rotates about an axis along the left-right direction of the vehicle body due to rotation of the transmission shaft; and a housing that accommodates the differential device and stores lubricating oil for lubricating the differential device, the housing having a protrusion on an inner wall that faces the outer periphery of the gear.

2. The axle device according to claim 1, wherein a part of the outer shape of the protrusion overlaps with the center of the vehicle body in the left-right direction when viewed from the front-rear direction of the vehicle body.

3. The axle device according to claim 2, wherein a part of the outer shape of the protrusion overlaps with an outer end of the gear in the left-right direction of the vehicle body when viewed from the front-rear direction of the vehicle body.

4. The axle device according to claim 3, wherein when the vehicle body is tilted forward by 6 degrees with respect to the longitudinal direction of the vehicle body, a part of the outer shape of the protrusion overlaps with the liquid surface of the lubricating oil.

5. An axle device as claimed in any one of claims 1 to 4, wherein a portion of the protrusion overlaps with the transmission shaft when viewed from the fore-and-aft direction of the vehicle body.

6. An axle device as claimed in any one of claims 1 to 4, wherein the housing is a front housing arranged at the front side in the fore-and-aft direction of the vehicle body, or a rear housing arranged at the rear side in the fore-and-aft direction of the vehicle body, and the protrusion is provided on a front inner wall of the front housing or a rear inner wall of the rear housing.

7. An axle assembly as claimed in any one of claims 1 to 4, wherein at least a portion of said projection is immersed in said lubricating oil.

8. An axle device as claimed in any one of claims 1 to 4, wherein the size of the gap between the protrusion and the gear is 5 mm or more and 10 mm or less.

9. An axle device as claimed in any one of claims 1 to 4, wherein, when viewed from the fore-and-aft direction of the vehicle body, a part of the outer shape of the protrusion is inclined so as to approach the centre of the axle as it moves from the tooth surface side of the gear towards the back surface side.

10. An axle device as described in claim 9, wherein, when viewed from the fore-and-aft direction of the vehicle body, at least a part of the outline of the protrusion overlaps with the outline of a triangle including two sides that incline from the upper and lower sides in the vertical direction of the vehicle body so as to approach the center of the axle as they move from the tooth surface side to the back side of the gear, and one side that follows the left-right center line of the vehicle body.

11. An axle device as claimed in any one of claims 1 to 4, further comprising a shroud that guides the lubricating oil that flows around the gear as the gear rotates, and when viewed from the fore-and-aft direction of the vehicle body, a part of the outer shape of the protrusion overlaps with the shroud.

12. An axle device as claimed in any one of claims 1 to 4, further comprising a wet multi-plate brake on the outer end side in the left-right direction of the vehicle body, at least a portion of the brake being immersed in the lubricating oil.

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