All-wheel drive vehicle

Abstract

The present invention provides an all-wheel-drive vehicle in which heat generation in the transfer case is easily suppressed in a configuration in which a transversely mounted power source is positioned. [Solution] The transfer case includes a gear chamber housing a transfer input gear and a transfer output gear, a coupling chamber housing a coupling member, a first oil passage, and a second oil passage. The first oil passage allows lubricating oil to flow from the upper space of the coupling chamber to the upper space of the gear chamber. The second oil passage allows lubricating oil to flow from the gear chamber to the coupling chamber. As a result, the lubricating oil is cooled by the coupling member that scoops up the lubricating oil in the coupling chamber, and the scooped-up lubricating oil is circulated from the coupling chamber to the gear chamber via the first oil passage. In the gear chamber, the meshed transfer input gear and transfer output gear are efficiently lubricated by the lubricating oil, suppressing heat generation. The lubricating oil that has lubricated the transfer input gear and transfer output gear is circulated from the gear chamber to the coupling chamber via the second oil passage.

Description

Technical Field

[0001] The present invention relates to an all-wheel drive vehicle equipped with a transfer that distributes power from a horizontally mounted power source to the front and rear wheels.

Background Art

[0002] An all-wheel drive vehicle including left and right front wheels, left and right rear wheels, a horizontally mounted power source with the axis of the power source output shaft in the vehicle width direction, a power transmission unit arranged coaxially with the power source output shaft for transmitting power from the power source, and a transfer for distributing the power from the power source transmitted through the power transmission unit to the front wheels and the rear wheels is well known. For example, the midship 4-wheel drive horizontally mounted transmission described in Patent Document 1 is such a vehicle. Patent Document 1 discloses providing a rear differential gear behind the main shaft of the horizontally mounted transmission (corresponding to the power transmission unit) and providing a transfer in front. Further, Patent Document 1 discloses taking out the output shaft of the transfer forward and connecting it to the front differential gear with a propeller shaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the all-wheel drive vehicle described in Patent Document 1, the transfer case is positioned in front of the transmission in the forward and reverse direction, that is, in front of the transversely mounted engine (corresponding to the power source). As a result, in the all-wheel drive vehicle described in Patent Document 1, it is difficult to secure passenger space in front of the engine in the forward and reverse direction, which is inherently difficult in a mid-ship layout. In such a mid-ship layout configuration, for example, it is conceivable to position the transfer case behind the engine in the forward and reverse direction, and transmit power from the output shaft of the transfer case facing backward to a second shaft via a connecting member, and then transmit from the second shaft to the front wheels. In this case, it is desirable to efficiently lubricate the gear section connecting the input shaft and output shaft of the transfer case to suppress heat generation in the transfer case.

[0005] The present invention was made against the above circumstances, and its objective is to provide an all-wheel drive vehicle in which heat generation of the transfer case is easily suppressed when a transversely mounted power source is arranged. [Means for solving the problem]

[0006] The gist of the first invention is an all-wheel drive vehicle comprising: (a) left and right front wheels, left and right rear wheels, a transversely mounted power source with the axis of the power source output shaft being in the vehicle width direction, a power transmission unit arranged coaxially with the power source output shaft for transmitting power from the power source, and a transfer for distributing the power from the power source transmitted via the power transmission unit to the front wheels and the rear wheels, wherein (b) the transfer includes a transfer input member, a transfer output member connected to the transfer input member, and a transfer case containing lubricating oil for housing the transfer input member and the transfer output member, (c) the transfer input member includes a transfer input shaft with one end connected to the power transmission unit for power transmission, and a transfer input gear fixed to the other end of the transfer input shaft, and (d) the transfer output member extends from one end to the other end (e) The transfer case includes a first transfer output shaft, a transfer output gear fixed to one end of the first transfer output shaft and meshing with the transfer input gear, a second transfer output shaft arranged parallel to the first transfer output shaft below or near below the first transfer output shaft in the vertical direction when mounted on a vehicle, and a connecting member connecting the other end of the first transfer output shaft and one end of the second transfer output shaft, wherein the transfer case includes a gear chamber housing the transfer input gear and the transfer output gear, a connecting chamber housing the connecting member, a first communicating oil passage for circulating the lubricating oil from the space above the connecting chamber in the vertical direction to the space above the gear chamber in the vertical direction, and a second communicating oil passage provided below or near below the first communicating oil passage in the vertical direction for circulating the lubricating oil from the gear chamber to the connecting chamber. [Effects of the Invention]

[0007] According to the first invention, a power transmission unit that transmits power from a horizontally mounted power source is arranged coaxially with the power source output shaft. The transfer distributes the power from the power source transmitted via the power transmission unit to the front and rear wheels. The transfer includes a transfer case that houses a transfer input member and a transfer output member, which are stored in lubricating oil. The transfer input member includes a transfer input gear fixed to the transfer input shaft. The transfer output member includes a transfer output gear fixed to the first transfer output shaft that meshes with the transfer input gear, and a connecting member that connects the first transfer output shaft and the second transfer output shaft. The second transfer output shaft is arranged parallel to the first transfer output shaft in the vertical direction, below or near below the first transfer output shaft. The transfer case includes a gear chamber housing a transfer input gear and a transfer output gear, a coupling chamber housing a coupling member, a first oil passage, and a second oil passage located below or near the first oil passage in the vertical direction. The first oil passage allows lubricating oil to flow from the space above the coupling chamber in the vertical direction to the space above the gear chamber in the vertical direction. The second oil passage allows lubricating oil to flow from the gear chamber to the coupling chamber. As a result, the lubricating oil is cooled by the coupling member that scoops up the lubricating oil in the coupling chamber, and the scooped-up lubricating oil is circulated from the coupling chamber to the gear chamber via the first oil passage. Then, in the gear chamber, the meshed transfer input gear and transfer output gear are efficiently lubricated by the lubricating oil, suppressing heat generation. The lubricating oil that has lubricated the transfer input gear and transfer output gear is circulated from the gear chamber to the coupling chamber via the second oil passage. Therefore, in all-wheel-drive vehicles with a transversely mounted power source, heat generation in the transfer case is more easily suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram illustrates the schematic configuration of a vehicle to which the present invention is applied. [Figure 2] This is a partial cross-sectional view of the transfer case and its vicinity, taken from the left side in the vehicle width direction. [Figure 3] This diagram illustrates the outline of the connecting oil passages through which lubricating oil flows. (a) is an external view of the transfer case as seen from the left side in the vehicle width direction, with a portion cut off. (b) is a partial cross-sectional view of the chain case as seen from the gear chamber side. (c) is an external view of the transfer case as seen from the rear left side in the vehicle width direction, with a portion cut off. [Figure 4] This diagram illustrates the outline of the connecting oil passages through which lubricating oil flows. (a) is an external view of the transfer as seen from the chain chamber side, cut off at the position of the connecting member. (b) is an external view of the transfer as seen from the chain chamber side, cut off at the midpoint of the first transfer output shaft. [Figure 5] This diagram illustrates the outline of the connecting oil passages through which lubricating oil flows. (a) is an external view of the transfer case, seen from the left rear in the vehicle width direction, with a portion cut off. (b) is a perspective view of the chain case, seen from the gear chamber side, with a portion of the chain chamber side cut off. [Figure 6] This diagram illustrates the outline of the second oil outlet passage. (a) is an external view of the gear case as seen from the chain chamber side. (b) is an external view of the transfer case as seen from the left rear in the vehicle width direction, with a portion cut off. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Examples]

[0010] Figure 1 is a diagram illustrating the schematic configuration of an all-wheel drive vehicle 10 to which the present invention is applied. In Figure 1, the all-wheel drive vehicle 10 comprises left and right front wheels 12, left and right rear wheels 14, left and right front drive shafts 16 that drive each of the front wheels 12, and left and right rear drive shafts 18 that drive each of the rear wheels 14. The all-wheel drive vehicle 10 also comprises a front differential gear 20 and a rear differential gear 22. The all-wheel drive vehicle 10 also comprises an engine 24, a transmission 26, a transfer case 28, a propeller shaft 30, and a coupling 32.

[0011] The front wheels 12 include the left front wheel 12L and the right front wheel 12R. The rear wheels 14 include the left rear wheel 14L and the right rear wheel 14R. The front drive shaft 16 includes the left front drive shaft 16L, which connects the front differential gear 20 to the left front wheel 12L, and the right front drive shaft 16R, which connects the front differential gear 20 to the right front wheel 12R. The rear drive shaft 18 includes the left rear drive shaft 18L, which connects the rear differential gear 22 to the left rear wheel 14L, and the right rear drive shaft 18R, which connects the rear differential gear 22 to the right rear wheel 14R. Note that the above "left and right" refers to left and right with respect to the forward direction of the all-wheel drive vehicle 10.

[0012] Engine 24 is, for example, a known internal combustion engine. Engine 24 is a transversely mounted engine in which the axis CL1 of the engine output shaft 24a is in the vehicle width direction (synonymous with the horizontal direction). Engine 24 is a transversely mounted power source of the present invention in which the axis of the power source output shaft is in the vehicle width direction. Engine output shaft 24a is the power source output shaft of the present invention. Engine 24 is located on the rear wheel 14 side. That is, engine 24 is located in the vicinity of the rear drive shaft 18. For example, engine 24 is located forward of the rear drive shaft 18 in the forward / reverse direction (synonymous with the vehicle's longitudinal direction). That is, engine 24 is in a so-called mid-ship layout.

[0013] The transmission 26 is positioned adjacent to the engine 24, coaxially with the engine output shaft 24a. The transmission 26 constitutes a part of the common power transmission path between the engine 24 and the front wheel 12, and between the engine 24 and the rear wheel 14. The transmission 26 transmits power from the engine 24 to the subsequent stages, i.e., to the front wheel 12 (also known as the front drive shaft 16) and the rear wheel 14 (also known as the rear drive shaft 18). The transmission 26 is the power transmission unit that transmits power from the engine 24 in the present invention. The transmission 26 is, for example, a known planetary gear type multi-stage transmission in which multiple gear stages with different gear ratios can be selectively established, a known continuously variable transmission in which the gear ratio can be changed continuously without stepless changes, or a known synchronous mesh type parallel shaft transmission. In Figure 1, a synchronous mesh type parallel shaft manual transmission is shown as an example of the transmission 26.

[0014] The rear differential gear 22 is positioned on the axis CL2 of the rear drive shaft 18, that is, coaxially with the rear drive shaft 18. The rear differential gear 22 is connected to the transmission 26. The rear differential gear 22 is a rear differential gear mechanism that distributes power from the engine 24 transmitted via the transmission 26 to each of the rear drive shafts 18, that is, to each of the rear wheels 14, and also allows for differential rotation between the left and right rear wheels 14.

[0015] The transfer case 28 is connected to the transmission 26. The transfer case 28 is a front-to-rear wheel power distribution device that distributes power from the engine 24, transmitted via the transmission 26, to the front wheels 12 and the rear wheels 14. However, since the rear differential gear 22 is connected to the transmission 26 without going through the transfer case 28, the transfer case 28 can also be viewed as a power distribution device that distributes power from the engine 24, transmitted via the transmission 26, to the front wheels 12.

[0016] The propeller shaft 30 is connected to the transfer 28. The propeller shaft 30 transmits the power from the engine 24 transmitted through the transfer 28 from the rear wheel 14 side to the front wheel 12 side. That is, the propeller shaft 30 transmits the power from the engine 24 transmitted through the transfer 28 to the front wheel 12 (the front drive shaft 16 is also synonymous).

[0017] The front differential gear 20 is disposed on the axis CL3 of the front drive shaft 16, that is, coaxially with the front drive shaft 16. The front differential gear 20 is connected to the propeller shaft 30 via a coupling 32. The front differential gear 20 is a differential gear mechanism for the front wheels that distributes the power from the engine 24 transmitted through the propeller shaft 30 to each of the front drive shafts 16, that is, to each of the front wheels 12, and allows differential rotation between the left and right in the front wheels 12.

[0018] The coupling 32 is provided in the power transmission path between the propeller shaft 30 and the front differential gear 20. The coupling 32 is a known electronically controlled coupling composed of, for example, a wet multi-plate clutch, in which the transmission torque is controlled by an electrical signal from an electronic control device (not shown) provided in the all-wheel drive vehicle 10. The coupling 32 can continuously change the torque distribution between the front and rear wheels, for example, between 0:100 and 50:50, by controlling the transmission torque.

[0019] In the power transmission path between the engine 24 and the rear wheels 14, the power from the engine 24 is transmitted to the rear wheels 14 through the transmission 26, the rear differential gear 22, the rear drive shaft 18, etc. in sequence. In the power transmission path between the engine 24 and the front wheels 12, the power from the engine 24 is transmitted to the front wheels 12 through the transmission 26, the transfer 28, the propeller shaft 30, the coupling 32, the front differential gear 20, the front drive shaft 16, etc. in sequence.

[0020] The all-wheel drive vehicle 10 is a vehicle capable of adjusting the drive torque distribution between the front wheels 12 and the rear wheels 14. Since the all-wheel drive vehicle 10 has two front wheels 12 and two rear wheels 14 respectively, and is a vehicle with four wheels in total, it is also a four-wheel drive vehicle. In this embodiment, all-wheel drive (AWD) and four-wheel drive (4WD) are synonymous. In addition to traveling in the AWD control (the AWD state is also synonymous) that drives the front wheels 12 and the rear wheels 14, the all-wheel drive vehicle 10 can also travel in the rear-wheel drive (RWD) control (the RWD state is also synonymous) that drives only the rear wheels 14, and the two-wheel drive (=2WD) control (the 2WD state is also synonymous).

[0021] By the way, in the all-wheel drive vehicle 10, it is conceivable to arrange the transfer 28 in front of the engine 24 in the forward and backward direction. Then, in the all-wheel drive vehicle 10 originally configured with a midship layout with a small living space, it becomes difficult to secure the living space in front of the engine 24. Also, it is necessary to separate the power transmission from the engine 24 via the transmission 26 to the rear differential gear 22 and the transfer 28, and the transfer 28 cannot be directly connected to the rear differential case 22c which is the input rotating member of the rear differential gear 22. Therefore, additional members such as gears and shafts are required, which may lead to an increase in cost and mass.

[0022] Therefore, in the all-wheel drive vehicle 10, the transfer 28 is arranged behind the engine 24 in the forward and backward direction. Also, the transfer 28 is directly connected to the rear differential case 22c and is connected to the transmission 26 via the rear differential case 22c.

[0023] Figure 2 is a partial cross-sectional view of the transfer 28 and its vicinity viewed from the left side in the vehicle width direction. The "vertical direction" in the figure indicates the vertical direction in the mounted state on the all-wheel drive vehicle 10, that is, the on-vehicle state.

[0024] In Figures 1 and 2, the transfer 28 comprises a transfer input member 50, a transfer output member 60 connected to the transfer input member 50, and a transfer case 80 that houses the transfer input member 50 and the transfer output member 60.

[0025] The transfer input member 50 comprises a transfer input shaft 52, one end of which is connected to the transmission 26 so as to transmit power, and a transfer input gear 54 fixed to the other end of the transfer input shaft 52. The transfer input shaft 52 is a rotating shaft, one end of which is connected to the transmission 26 via an input rotating member of the rear differential gear 22. For example, the transfer input shaft 52 is connected to the transmission 26 by one end being connected to the rear differential case 22c. The rear differential case 22c is connected to the transmission 26 via a rear differential ring gear 22r, which is integrally connected to the rear differential case 22c. The rear differential ring gear 22r functions as an input rotating member of the rear differential gear 22, similar to the rear differential case 22c. The transfer input shaft 52 is positioned on the axis CL2 of the rear drive shaft 18, alongside the rear differential gear 22. Furthermore, depending on the position of the rear differential ring gear 22r, the transfer input shaft 52 may also be connected to the transmission 26 by having one end connected to the rear differential ring gear 22r. Also, "fixed" is synonymous with "fixed so that relative rotation is impossible."

[0026] The transfer output member 60 includes a first transfer output shaft 62, a transfer output gear 64 fixed to one end of the first transfer output shaft 62, a second transfer output shaft 66 arranged parallel to the first transfer output shaft 62, and a connecting member 70.

[0027] The first transfer output shaft 62 is a rotating shaft that extends from one end to the other in the rearward direction in the forward and backward direction. The transfer output gear 64 is a gear that meshes with the transfer input gear 54. For example, the transfer input gear 54 and the transfer output gear 64 are a gear pair that constitutes a hypoid gear. The transfer output gear 64 is a hypoid pinion that, together with the transfer input gear 54, constitutes a hypoid gear.

[0028] The connecting member 70 is a member that connects the other end of the first transfer output shaft 62 to one end of the second transfer output shaft 66. The connecting member 70 comprises a first gear 72, a second gear 74, and a transmission member 76. The first gear 72 is a gear fixed to the other end of the first transfer output shaft 62. The second gear 74 is a gear fixed to one end of the second transfer output shaft 66. The transmission member 76 is a member wrapped around the first gear 72 and the second gear 74. For example, the transmission member 76 is a chain or a belt. In particular, the transmission member 76 is a silent chain.

[0029] The second transfer output shaft 66 is a rotating shaft whose other end is connected to the propeller shaft 30. The second transfer output shaft 66 is located below or near below the first transfer output shaft 62 in the vertical direction when mounted on the vehicle. As a result, the second transfer output shaft 66 passes below the engine 24 in the vertical direction when mounted on the vehicle and is connected to the propeller shaft 30.

[0030] The transfer case 80 includes a gear case 80a having a gear chamber Rg and a chain case 80b having a chain chamber Rc. The gear chamber Rg is a hypoid gear chamber that houses the transfer input gear 54 and the transfer output gear 64, that is, a hypoid gear. The chain chamber Rc is the connecting chamber of the present invention that houses the connecting member 70.

[0031] The transfer case 80 stores lubricating oil FLD. Lubricating oil FLD is an oil that lubricates, for example, hypoid gears (transfer input gear 54, transfer output gear 64) and connecting members 70. The lubricating oil FLD in both the gear chamber Rg and the chain chamber Rc is circulated. In the all-wheel drive vehicle 10, the force of the connecting members 70 in the chain chamber Rc stirring up the lubricating oil FLD is used to circulate the lubricating oil FLD from the chain chamber Rc to the gear chamber Rg (see thick arrow A). In addition, in the all-wheel drive vehicle 10, the lubricating oil FLD is agitated by the hypoid gears in the gear chamber Rg, or the amount of oil in the gear chamber Rg is increased, causing the lubricating oil FLD to circulate from the gear chamber Rg to the chain chamber Rc (see thick arrow B). As a result, the all-wheel drive vehicle 10 can be made oil pump-less, which reduces costs and mass.

[0032] The heat generated in the hypoid gears (transfer input gear 54, transfer output gear 64) is greater than the heat generated in the connecting member 70 (i.e., the heat generated by the chain). Alternatively, the effect of cooling the lubricating oil FLD by the scraping action of the connecting member 70 can also be obtained. The lubricating oil FLD, heated in the gear chamber Rg by the heat generated in the hypoid gears, is circulated to the chain chamber Rc and cooled by the scraping action of the connecting member 70. The lubricating oil FLD cooled in the chain chamber Rc is circulated to the gear chamber Rg, and the hypoid gears are cooled by the lubricating oil FLD, thereby suppressing the heat generated in the hypoid gears.

[0033] Figures 3, 4, and 5 are diagrams illustrating the outlines of the connecting oil passages through which the lubricating oil FLD flows. Figure 3(a) is an external view of the transfer case 28 as seen from the left side in the vehicle width direction, with a portion cut off. Figure 3(b) is a partial cross-sectional view of the chain case 80b as seen from the gear chamber Rg side. Figure 3(c) is an external view of the transfer case 80 as seen from the rear left side in the vehicle width direction, with a portion cut off. Figure 4(a) is an external view of the transfer case 28 as seen from the chain chamber Rc side, with a cut-off at the position of the connecting member 70. Figure 4(b) is an external view of the transfer case 28 as seen from the chain chamber Rc side, with a cut-off at the intermediate position of the first transfer output shaft 62. Figure 5(a) is an external view of the transfer case 28 as seen from the rear left side in the vehicle width direction, with a cut-off. Figure 5(b) is a perspective view of the chain case 80b as seen from the gear chamber Rg side, with a portion of the chain chamber Rc side cut out.

[0034] In Figures 3-5, the transfer case 80 further comprises a first connecting oil passage 82 and a second connecting oil passage 84. The first connecting oil passage 82 is an oil passage that circulates lubricating oil FLD from the space above the chain chamber Rc in the vertical direction when mounted on a vehicle to the space above the gear chamber Rg in the vertical direction when mounted on a vehicle. The second connecting oil passage 84 is located below or near below the first connecting oil passage 82 in the vertical direction when mounted on a vehicle. The second connecting oil passage 84 is an oil passage that circulates lubricating oil FLD from the gear chamber Rg to the chain chamber Rc. The first connecting oil passage 82 includes an inlet oil passage 82a, an upper intermediate chamber 82b, and an introduction oil passage 82c. In the first connecting oil passage 82, lubricating oil FLD flows in the order of inlet oil passage 82a, upper intermediate chamber 82b, and introduction oil passage 82c. The second connecting oil passage 84 includes an outlet oil passage 84a, a lower intermediate chamber 84b, and an outlet oil passage 84c. In the second connecting oil passage 84, lubricating oil FLD flows in the order of outlet oil passage 84c, lower intermediate chamber 84b, and outlet oil passage 84a (see the thick arrow C in Figure 5(a)).

[0035] The inflow oil passage 82a is an oil passage through which lubricating oil FLD flows in from the space above the chain chamber Rc. The inflow oil passage 82a has ribs that protrude from the upper surface of the inner wall of the chain case 80b in the vertical direction when mounted on a vehicle. The ribs of the inflow oil passage 82a are members that scrape off the lubricating oil FLD that has been scraped up by the connecting member 70. The inflow oil passage 82a has a receiving tray integrally formed with the ribs to receive the lubricating oil FLD scraped off by the ribs. The inflow oil passage 82a is connected to the upper intermediate chamber 82b and is inclined so that the lubricating oil FLD flows into the upper intermediate chamber 82b when mounted on a vehicle. In this embodiment, two inflow oil passages 82a are provided.

[0036] The upper intermediate chamber 82b is a small chamber located between the inflow oil passage 82a and the introduction oil passage 82c, through which the lubricating oil FLD from the inflow oil passage 82a flows to the introduction oil passage 82c (see the thick arrow D in Figure 4(b)). The upper intermediate chamber 82b connects the inflow oil passage 82a and the introduction oil passage 82c, and the flow rate of the lubricating oil FLD in the first connecting oil passage 82 can be adjusted in advance by design or experimentally depending on the shape of the upper intermediate chamber 82b. In the transfer case 80, the amount of lubricating oil FLD circulated is predetermined by the size of the inflow oil passage 82a and the upper intermediate chamber 82b, depending on the rotational speed of the connecting member 70 and the temperature of the lubricating oil FLD.

[0037] The introduction oil passage 82c is an oil passage that guides lubricating oil FLD into the space above the gear chamber Rg. The introduction oil passage 82c is, for example, a communication hole formed in the gear case 80a that connects the upper intermediate chamber 82b and the space above the gear chamber Rg. The introduction oil passage 82c is inclined so that, for example, when installed in a vehicle, the lubricating oil FLD flows from the upper intermediate chamber 82b to the space above the gear chamber Rg.

[0038] The oil outflow passage 84a is an oil passage through which lubricating oil FLD flows into the chain chamber Rc. Multiple oil outflow passages 84a are formed, for example, on the outer circumference of the first transfer output shaft 62 radially outward on the side wall of the chain case 80b on the gear case 80a side, and vertically downward in the vehicle-mounted state. The oil outflow passage 84a is in communication with the lower intermediate chamber 84b.

[0039] The lower intermediate chamber 84b is a small chamber located between the outlet oil passage 84a and the outlet oil passage 84c, which allows lubricating oil FLD from the outlet oil passage 84c to flow into the outlet oil passage 84a. The lower intermediate chamber 84b connects the outlet oil passage 84a and the outlet oil passage 84c, and the flow rate of lubricating oil FLD in the second connecting oil passage 84 can be adjusted in advance by design or experimentally depending on the shape of the lower intermediate chamber 84b. In the transfer case 80, the amount of lubricating oil FLD circulated is predetermined by the size of the outlet oil passage 84a and the lower intermediate chamber 84b, depending on the rotational speed of the connecting member 70 and the temperature of the lubricating oil FLD.

[0040] The oil outlet passage 84c is an oil passage that guides the lubricating oil FLD from the gear chamber Rg to the chain chamber Rc. The oil outlet passage 84c is, for example, an oil passage that connects the gear chamber Rg and the lower intermediate chamber 84b. In other words, the oil outlet passage 84c is an oil passage that guides the lubricating oil FLD from the gear chamber Rg to the lower intermediate chamber 84b. The oil outlet passage 84c is formed, for example, by the internal space (gap) of the bearing 90 that supports the first transfer output shaft 62 in the gear case 80a, which is provided in an all-wheel drive vehicle 10.

[0041] Here, the dashed line E shown in Figure 2 indicates a predetermined oil level H in the vertical direction of the gear chamber Rg when mounted on a vehicle. The predetermined oil level H is a predetermined oil level (assumed oil level) in the gear chamber Rg that ensures a sufficient amount of lubricating oil FLD for proper lubrication and cooling of, for example, hypoid gears (transfer input gear 54, transfer output gear 64). However, if the flow rate of the first connecting oil passage 82 is greater than the flow rate of the second connecting oil passage 84, the amount of lubricating oil FLD in the gear chamber Rg becomes excessively large. Therefore, in order to prevent or suppress the amount of lubricating oil FLD in the gear chamber Rg from becoming too large, the second connecting oil passage 84 further includes a second outlet oil passage 84d. Any lubricating oil FLD exceeding a predetermined oil level H in the gear chamber Rg is circulated exclusively from the gear chamber Rg to the chain chamber Rc via the second oil outlet passage 84d.

[0042] Figure 6 is a diagram illustrating the outline of the second oil outlet passage 84d. Figure 6(a) is an external view of the gear case 80a as seen from the chain chamber Rc side. Figure 6(b) is an external view of the transfer case 28 as seen from the left rear in the vehicle width direction, with a portion cut off.

[0043] In Figure 6, the second oil outlet passage 84d is a separate oil passage from the oil outlet passage 84c (see Figures 3 and 5) that guides the lubricating oil FLD from the gear chamber Rg to the lower intermediate chamber 84b. The second oil outlet passage 84d is located at a position higher than a predetermined oil level height H in the gear chamber Rg. The second oil outlet passage 84d is a communication hole formed in a concave shape on the inner surface of the gear case 80a where the bearing 90 is located, for example, to connect the gear chamber Rg and the lower intermediate chamber 84b.

[0044] As described above, according to this embodiment, the transfer case 28 includes a transfer case 80 that houses a transfer input member 50 and a transfer output member 60, and stores lubricating oil FLD. The transfer case 80 includes a gear chamber Rg that houses a transfer input gear 54 and a transfer output gear 64, a chain chamber Rc that houses a connecting member 70, a first oil passage 82, and a second oil passage 84 that is located below or near the first oil passage 82 in the vertical direction when mounted on a vehicle. The first oil passage 82 allows lubricating oil FLD to flow from the space above the chain chamber Rc in the vertical direction when mounted on a vehicle to the space above the gear chamber Rg in the vertical direction when mounted on a vehicle. The second oil passage 84 allows lubricating oil FLD to flow from the gear chamber Rg to the chain chamber Rc. As a result, the lubricating oil FLD is cooled by the connecting member 70 that scoops up the lubricating oil FLD in the chain chamber Rc, and the scooped-up lubricating oil FLD is circulated from the chain chamber Rc to the gear chamber Rg via the first connecting oil passage 82. Then, in the gear chamber Rg, the meshed transfer input gear 54 and transfer output gear 64 are efficiently lubricated by the lubricating oil FLD, suppressing heat generation. The lubricating oil FLD that has lubricated the transfer input gear 54 and transfer output gear 64 is circulated from the gear chamber Rg to the chain chamber Rc via the second connecting oil passage 84. Therefore, in an all-wheel drive vehicle 10 with a transversely mounted engine 24, heat generation in the transfer case 28 is easily suppressed.

[0045] Furthermore, according to this embodiment, the transfer input gear 54 and the transfer output gear 64 are a gear pair constituting a hypoid gear. The connecting member 70 includes a first gear 72 fixed to the other end of the first transfer output shaft 62, a second gear 74 fixed to one end of the second transfer output shaft 66, and a transmission member 76 wrapped around the first gear 72 and the second gear 74. This simplifies the configuration for scooping up the lubricating oil FLD accumulated in the lower part of the case housing the connecting member 70 in the vertical direction when mounted on a vehicle. Also, since the connecting member 70, including the transmission member 76 which is a chain or belt, generates less heat than the hypoid gear, the lubricating oil FLD cooled in the chain chamber Rc is circulated to the gear chamber Rg, and the heat generation of the hypoid gear is efficiently suppressed.

[0046] Furthermore, according to this embodiment, the first connecting oil passage 82 includes an inlet oil passage 82a, an upper intermediate chamber 82b, and an introduction oil passage 82c. The second connecting oil passage 84 includes an outlet oil passage 84a, a lower intermediate chamber 84b, and an outlet oil passage 84c. As a result, the flow rate of lubricating oil FLD in the first connecting oil passage 82 and the second connecting oil passage 84 can be adjusted in advance by the shape of the upper intermediate chamber 82b and the shape of the lower intermediate chamber 84b.

[0047] Furthermore, according to this embodiment, the second oil passage 84 further includes a second oil outlet passage 84d. As a result, the amount of lubricating oil FLD in the gear chamber Rg that exceeds a predetermined oil level H is circulated exclusively to the chain chamber Rc via the second oil outlet passage 84d, thereby preventing or suppressing an excessive amount of lubricating oil FLD in the gear chamber Rg.

[0048] Furthermore, according to this embodiment, the transversely mounted engine 24, whose engine output shaft 24a's axis CL1 is in the vehicle width direction, is positioned near the front rear drive shaft 18 in the forward direction relative to the rear drive shaft 18. The transmission 26, which transmits power from the engine 24, is positioned coaxially with the engine output shaft 24a. The rear differential gear 22 distributes the power from the engine 24 transmitted via the transmission 26 to each of the rear drive shafts 18. The transfer case 28 distributes the power from the engine 24 transmitted via the transmission 26 to the front wheels 12. The propeller shaft 30 transmits the power from the engine 24 transmitted via the transfer case 28 to the front drive shafts 16. The front differential gear 20 distributes the power from the engine 24 transmitted via the propeller shaft 30 to each of the front drive shafts 16. The transfer case 28 is positioned rearward relative to the engine 24 in the forward direction. This makes it easier to secure passenger space in front of the engine 24 in the forward and backward directions in an all-wheel-drive vehicle 10 configured to have a transversely mounted engine 24 positioned near the rear drive shaft 18.

[0049] Furthermore, according to this embodiment, one end of the transfer input shaft 52 is connected to the transmission 26 via the input rotating member (rear differential case 22c, rear differential ring gear 22r) of the rear differential gear 22, and is positioned coaxially with the rear drive shaft 18 and alongside the rear differential gear 22. This allows the transfer 28 to be directly connected to the rear differential case 22c, eliminating the need for additional components such as gears and shafts, thereby suppressing increases in cost and mass.

[0050] Furthermore, according to this embodiment, the first transfer output shaft 62 extends from one end to the other toward the rear in the forward and backward direction, and the other end of the second transfer output shaft 66 is connected to the propeller shaft 30. This allows the transfer 28 to appropriately distribute the power from the engine 24 transmitted via the transmission 26 to the front wheels 12 in a configuration where the transfer 28 is positioned behind the engine 24 in the forward and backward direction.

[0051] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is also applicable to other embodiments.

[0052] For example, in the above embodiment, the connecting member 70 may include a gear fixed to the other end of the first transfer output shaft 62 and a gear fixed to one end of the second transfer output shaft 66, and these gears may be meshed directly or via a counter gear. Even in this configuration, the connecting member 70 scrapes up the lubricating oil FLD, so a certain effect can be obtained in which the heat generation of the transfer 28 is more easily suppressed.

[0053] Furthermore, in the above-described embodiment, the power source may be an electric motor instead of, or in addition to, the engine 24. If the power source is only an electric motor, the power transmission unit may be a gear mechanism having a single gear ratio instead of, for example, the transmission 26.

[0054] Furthermore, in the above-described embodiment, the first transfer output shaft 62 was a rotating shaft extending from one end to the other toward the rear in the forward / reverse direction. However, depending on the configuration or position of the transfer 28, it may also be a rotating shaft extending from one end to the other toward the front in the forward / reverse direction. The transfer 28 is not limited to being located on the rear wheel 14 side, for example, but may also be located on the front wheel 12 side. Therefore, the power source is not limited to a mid-ship layout.

[0055] Furthermore, in the above-described embodiment, the coupling 32 may be provided, for example, in the power transmission path between the front differential gear 20 and the front drive shaft 16. Alternatively, the coupling 32 may be replaced with, for example, a clutch that connects or disconnects the power transmission path, or a center differential device that allows differential rotation between the front wheels 12 and the rear wheels 14. In other words, the coupling 32 may be replaced with a mechanism other than the coupling 32 that, when combined with the transfer case 28, enables driving in AWD mode.

[0056] It should be noted that the above-described embodiment is merely one possible design, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0057] 10: All-wheel drive vehicle 12: Front wheel 12L: Left front wheel 12R: Right front wheel 14: Rear wheel 14L: Left rear wheel 14R: Right rear wheel 16: Front drive shaft 16L: Left front drive shaft 16R: Right front drive shaft 18: Rear drive shaft 18L: Left rear drive shaft 18R: Right rear drive shaft 20: Front differential gear 22: Rear differential gear 22c: Rear differential case (input rotating member of rear differential gear) 22r: Rear differential ring gear (input rotating member of rear differential gear) 24: Engine (power source) 24a: Engine output shaft (power source output shaft) 26: Transmission (power transmission section) 28: Transfer case 30: Propeller shaft 50: Transfer case input member 52: Transfer case input shaft 54: Transfer case input gear 60: Transfer output member 62: First transfer output shaft 64: Transfer output gear 66: Second transfer output shaft 70: Connecting member 72: First gear 74: Second gear 76: Transmission member 80: Transfer case 82: First connecting oil passage 82a: Inflow oil passage 82b: Upper intermediate chamber 82c: Inlet oil passage 84: Second connecting oil passage 84a: Outflow oil passage 84b: Lower intermediate chamber 84c: Outlet oil passage 84d: Second outlet oil passage FLD: Lubricating oil Rc: Chain chamber (connecting chamber) Rg: Gear chamber

Claims

1. An all-wheel-drive vehicle comprising: left and right front wheels, left and right rear wheels, a transversely mounted power source with the axis of the power source output shaft oriented in the vehicle width direction, a power transmission unit arranged coaxially with the power source output shaft for transmitting power from the power source, and a transfer case for distributing the power from the power source transmitted via the power transmission unit to the front wheels and the rear wheels, The transfer includes a transfer input member, a transfer output member connected to the transfer input member, and a transfer case containing lubricating oil that houses the transfer input member and the transfer output member. The transfer input member includes a transfer input shaft, one end of which is connected to the power transmission unit in a power transmission manner, and a transfer input gear fixed to the other end of the transfer input shaft. The transfer output member includes a first transfer output shaft extending from one end to the other, a transfer output gear fixed to one end of the first transfer output shaft and meshing with the transfer input gear, a second transfer output shaft positioned parallel to the first transfer output shaft below or near the first transfer output shaft in the vertical direction when mounted on a vehicle, and a connecting member connecting the other end of the first transfer output shaft and one end of the second transfer output shaft. An all-wheel drive vehicle characterized in that the transfer case includes a gear chamber housing the transfer input gear and the transfer output gear, a coupling chamber housing the coupling member, a first connecting oil passage for circulating the lubricating oil from the space above the coupling chamber in the vertical direction to the space above the gear chamber in the vertical direction, and a second connecting oil passage provided below or near the first connecting oil passage in the vertical direction for circulating the lubricating oil from the gear chamber to the coupling chamber.

2. The transfer input gear and the transfer output gear are a gear pair that constitutes a hypoid gear. The all-wheel drive vehicle according to claim 1, characterized in that the connecting member includes a first gear fixed to the other end of the first transfer output shaft, a second gear fixed to one end of the second transfer output shaft, and a transmission member wrapped around the first gear and the second gear.

3. The first connecting oil passage includes an inflow oil passage through which the lubricating oil flows from the upper space of the connecting chamber, an introduction oil passage that guides the lubricating oil to the upper space of the gear chamber, and an upper intermediate chamber that allows the lubricating oil from the inflow oil passage to flow into the introduction oil passage. The all-wheel drive vehicle according to claim 1, characterized in that the second connecting oil passage includes an outlet oil passage that guides the lubricating oil from the gear chamber to the connecting chamber, an outlet oil passage through which the lubricating oil flows out into the connecting chamber, and a lower intermediate chamber that allows the lubricating oil from the outlet oil passage to flow into the outlet oil passage.

4. The all-wheel drive vehicle according to claim 3, characterized in that the second connecting oil passage further includes a second outlet oil passage provided at a position higher than a predetermined oil level height in the gear chamber in the vertical direction, which guides the lubricating oil in the gear chamber to the lower intermediate chamber.

5. The system further comprises left and right front drive shafts that drive each of the front wheels, left and right rear drive shafts that drive each of the rear wheels, a rear differential gear arranged coaxially with the rear drive shafts and distributing power from the power source transmitted via the power transmission unit to each of the rear drive shafts, a propeller shaft that transmits power from the power source transmitted via the transfer case to the front drive shafts, and a front differential gear arranged coaxially with the front drive shafts and distributing power from the power source transmitted via the propeller shaft to each of the front drive shafts. The power source is a transversely mounted engine positioned near the rear drive shaft in the forward direction relative to the rear drive shaft, with the axis of the engine output shaft oriented in the vehicle width direction. The power transmission unit is a transmission that transmits power from the engine and is arranged coaxially with the engine output shaft. The transfer case is positioned rearward in the forward / reverse direction relative to the engine, The transfer input shaft has one end connected to the transmission via the input rotating member of the rear differential gear, and is arranged coaxially with the rear drive shaft and alongside the rear differential gear. The first transfer output shaft extends from one end to the other in the rearward direction in the forward and backward direction, The all-wheel drive vehicle according to any one of claims 1 to 4, characterized in that the other end of the second transfer output shaft is connected to the propeller shaft.

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