All-wheel drive vehicle

Abstract

The invention provides an all-wheel drive vehicle which can easily suppress heat generation of a transfer case in a structure provided with a horizontal power source. The transfer case comprises a gear chamber for accommodating the transfer case input gear and the transfer case output gear; a connection chamber for accommodating the connection member; a first communication oil passage; and a second communication oil passage. The first communication oil passage causes the lubricating oil to flow from a space above the connection chamber to a space above the gear chamber. The second communication oil passage causes the lubricating oil to flow from the gear chamber to the connection chamber. As a result, the lubricating oil is cooled by the coupling member that scrapes the lubricating oil in the coupling chamber, and the scraped lubricating oil circulates from the coupling chamber to the gear chamber via the first communication oil passage. In a gear chamber, a transfer case input gear and a transfer case output gear which are meshed with each other are efficiently lubricated by lubricating oil, thereby suppressing heat generation. Lubricating oil that lubricates the transfer case input gear and the transfer case output gear circulates from the gear chamber to the connection chamber via a second communication oil passage.

Description

Technical Field

[0001] The present invention relates to an all-wheel drive vehicle having a transfer case that distributes power from a transversely mounted power source to the front and rear wheels. Background Technology

[0002] A known all-wheel drive vehicle includes: left and right front wheels; left and right rear wheels; a transversely mounted power source, the axis of which is in the vehicle width direction; a power transmission unit disposed coaxially with the power source output shaft and transmitting power from the power source; and a transfer case that distributes the power from the power source transmitted via the power transmission unit to the front wheels and the rear wheels. For example, the mid-mounted transversely mounted four-wheel drive transmission described in Patent Document 1 is such an example. Patent Document 1 discloses that a rear differential gear is provided rearward from the main shaft of the transversely mounted transmission (equivalent to the power transmission unit), and a transfer case is provided in front of it.

[0003] Furthermore, Patent Document 1 discloses the following: the output shaft of the transfer case is taken out facing forward and connected to the front differential gear via a drive shaft.

[0004] Patent Document 1: Japanese Patent Application Publication No. 5-58178 Summary of the Invention

[0005] In the all-wheel-drive vehicle described in Patent Document 1, the transfer case is positioned in front of the transmission in the forward / reverse direction, i.e., in front of the transversely mounted engine (equivalent to the power source). Therefore, in the all-wheel-drive vehicle described in Patent Document 1, with its inherently cramped mid-engine layout, it is difficult to ensure sufficient living space in front of the engine in the forward / reverse direction. In this mid-engine configuration, for example, it is possible to position the transfer case rearward relative to the engine in the forward / reverse direction, and transmit power from the output shaft of the rearward-facing transfer case to a second shaft via a connecting member, and from the second shaft to the front wheels. In this case, it is desirable to efficiently lubricate the gears connecting the input and output shafts of the transfer case, thereby suppressing heat generation in the transfer case.

[0006] The present invention was made against the background described above, and its purpose is to provide an all-wheel drive vehicle in which the heat generation of the transfer case is easily suppressed in a structure with a transversely mounted power source.

[0007] The purpose of the first invention is to (a) provide an all-wheel drive vehicle having: left and right front wheels;

[0008] (a) Left and right rear wheels; a transverse power source, the axis of which is in the vehicle width direction; a power transmission unit, which is arranged on the same axis as the power source output shaft and transmits power from the power source; and a transfer case, which distributes the power from the power source transmitted via the power transmission unit to the front wheels and the rear wheels, (b) the transfer case includes: a transfer case input component; a transfer case output component connected to the transfer case input component; and a transfer case housing, which stores lubricating oil and houses the transfer case input component and the transfer case output component, (c) the transfer case input component includes: a transfer case input shaft, one end of which is power-transmittably connected to the power transmission unit; and a transfer case input gear, which is fixedly disposed at the other end of the transfer case input shaft, (d) the transfer case output component includes: a first transfer case output shaft, which extends from one end to the other end; and a transfer case output gear. The first transfer case is fixedly disposed at one end of the first transfer case output shaft and meshes with the transfer case input gear; the second transfer case output shaft is disposed parallel to the first transfer case output shaft in the vertical direction below or near the lower part of the first transfer case output shaft in the vehicle-mounted state; and a connecting member connects the other end of the first transfer case output shaft to one end of the second transfer case output shaft. (e) The transfer case housing includes: a gear chamber that houses the transfer case input gear and the transfer case output gear; a connecting chamber that houses the connecting member; a first connecting oil passage that allows lubricating oil to flow 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 connecting oil passage disposed further below or near the lower part of the vertical direction than the first connecting oil passage, allowing lubricating oil to flow from the gear chamber to the connecting chamber.

[0009] Invention Effects

[0010] According to the first invention, a power transmission unit that transmits power from a transversely mounted power source is arranged coaxially with the power source output shaft. The transfer case distributes the power from the power source transmitted via the power transmission unit to the front and rear wheels. The transfer case includes a transfer case housing that stores lubricating oil and houses a transfer case input component and a transfer case output component. The transfer case input component includes a transfer case input gear fixedly mounted on the transfer case input shaft. The transfer case output component includes: a transfer case output gear fixedly mounted on a first transfer case output shaft and meshing with the transfer case input gear; and a connecting component connecting the first transfer case output shaft and a second transfer case output shaft. The second transfer case output shaft is arranged parallel to the first transfer case output shaft in the vertical direction, below or near the first transfer case output shaft. The transfer case housing includes: a gear chamber housing the transfer case input gear and the transfer case output gear; a connecting chamber housing the connecting components; a first connecting oil passage; and a second connecting oil passage located vertically below or near the lower part of the first connecting oil passage. The first connecting oil passage allows lubricating oil to flow from the upper space of the connecting chamber to the upper space of the gear chamber in the vertical direction. The second connecting oil passage allows lubricating oil to flow from the gear chamber to the connecting chamber. Thus, the lubricating oil is cooled by the connecting components that scrape lubricating oil in the connecting chamber, and the scraped lubricating oil circulates from the connecting chamber to the gear chamber via the first connecting oil passage. Furthermore, in the gear chamber, the meshing transfer case input gear and transfer case output gear are efficiently lubricated by lubricating oil, thereby suppressing heat generation. The lubricating oil lubricating the transfer case input gear and transfer case output gear circulates from the gear chamber to the connecting chamber via the second connecting oil passage. Therefore, in all-wheel drive vehicles with a transversely mounted power source, transfer case heat generation is easily suppressed. Attached Figure Description

[0011] Figure 1 This is a diagram illustrating the general structure of a vehicle to which the present invention is applied.

[0012] Figure 2 This is a partial cross-sectional view of the transfer case or its vicinity, viewed from the left side in the vehicle width direction.

[0013] Figure 3 is a schematic diagram illustrating the connecting oil passages that allow lubricating oil to flow. Figure 3(a) is an external view of the transfer case 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 housing from the gear chamber side. Figure 3(c) is an external view of the transfer case housing from the rear left side in the vehicle width direction, with a portion cut off.

[0014] Figure 4 is a schematic diagram illustrating the connecting oil passage for the flow of lubricating oil. Figure 4(a) is an external view of the transfer case from the chain chamber side, with the connecting parts cut off. Figure 4(b) is an external view of the transfer case from the chain chamber side, with the middle position of the first transfer case output shaft cut off.

[0015] Figure 5 is a schematic diagram illustrating the connecting oil passages that allow lubricating oil to flow. Figure 5(a) is an external view of the transfer case from the rear left side in the vehicle width direction, with a portion cut off. Figure 5(b) is a perspective view of the chain housing from the gear chamber side, with a portion of the chain chamber side cut off.

[0016] Figure 6 is a diagram illustrating the outline of the second outgoing oil circuit. Figure 6(a) is an external view of the gear housing from the chain chamber side. Figure 6(b) is an external view of the transfer case from the rear left side in the vehicle width direction, with a portion cut off. Detailed Implementation

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0018] Figure 1 This is a diagram illustrating the schematic structure of an all-wheel drive vehicle 10 to which the present invention is applied. Figure 1 The all-wheel drive vehicle 10 includes: left and right front wheels 12; left and right rear wheels 14; left and right front drive axles 16, driving the front wheels 12 respectively; and left and right rear drive axles 18, driving the rear wheels 14 respectively. Furthermore, the all-wheel drive vehicle 10 includes a front differential gear 20 and a rear differential gear 22. Additionally, the all-wheel drive vehicle 10 includes an engine 24, a transmission 26, a transfer case 28, a driveshaft 30, and a coupler 32.

[0019] The front wheels 12 include a left front wheel 12L and a right front wheel 12R. The rear wheels 14 include a left rear wheel 14L and a right rear wheel 14R. The front drive axle 16 includes a left front drive axle 16L connecting the front differential gear 20 and the left front wheel 12L, and a right front drive axle 16R connecting the front differential gear 20 and the right front wheel 12R. The rear drive axle 18 includes a left rear drive axle 18L connecting the rear differential gear 22 and the left rear wheel 14L, and a right rear drive axle 18R connecting the rear differential gear 22 and the right rear wheel 14R. Furthermore, the term "left and right" refers to left and right relative to the forward direction of the all-wheel drive vehicle 10.

[0020] Engine 24 is, for example, a known internal combustion engine. Engine 24 is a transversely mounted engine with the axis CL1 of the engine output shaft 24a set in the vehicle width direction (also indicating the horizontal direction). Engine 24 is a transversely mounted power source of the present invention with the axis of the power source output shaft 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 side of the rear wheel 14. That is, engine 24 is located near the rear drive shaft 18. For example, engine 24 is located in front of the rear drive shaft 18 in the forward and reverse direction (also indicating the vehicle's front and rear directions). That is, engine 24 is configured in a so-called mid-mounted layout.

[0021] The transmission 26 is coaxial with and adjacent to the engine output shaft 24a. The transmission 26 constitutes part of a common power transmission path in both the power transmission path between the engine 24 and the front wheels 12 and the power transmission path between the engine 24 and the rear wheels 14. The transmission 26 transmits power from the engine 24 to the rear section, i.e., the front wheels 12 (the same applies to the front drive shaft 16) or the rear wheels 14 (the same applies to the rear drive shaft 18). The transmission 26 is the power transmission unit of the present invention for transmitting power from the engine 24. The transmission 26 can be, for example, a known planetary gear multi-speed transmission that selectively establishes multiple gears with different gear ratios, a known continuously variable transmission (CVT) that allows stepless continuous change of gear ratios, or a known synchronous meshing parallel shaft transmission, etc. Furthermore, in Figure 1 In the example 26, a synchronous meshing type parallel shaft manual transmission is shown.

[0022] The rear differential gear 22 is mounted on the shaft center CL2 of the rear drive shaft 18, i.e., coaxial with the rear drive shaft 18. The rear differential gear 22 is connected to the transmission 26. The rear differential gear 22 distributes the power from the engine 24 transmitted via the transmission 26 to each axle of the rear drive shaft 18, i.e., each axle of the rear wheels 14, and is a differential gear mechanism for the rear wheels 14 that allows differential rotation of the left and right rear wheels.

[0023] Transfer case 28 is connected to transmission 26. Transfer case 28 is a front-to-rear wheel power distribution device that distributes power from engine 24 transmitted via transmission 26 to front wheels 12 and rear wheels 14. In addition, the rear differential gear 22 is connected to transmission 26 without passing through transfer case 28, so transfer case 28 can also be regarded as a power distribution device that distributes power from engine 24 transmitted via transmission 26 to front wheels 12.

[0024] Driveshaft 30 is connected to transfer case 28. Driveshaft 30 transmits power from engine 24 via transfer case 28 from the rear wheel 14 side to the front wheel 12 side. That is, driveshaft 30 transmits power from engine 24 via transfer case 28 to front wheel 12 (front driveshaft 16 has the same meaning).

[0025] The front differential gear 20 is mounted on the shaft center CL3 of the front drive shaft 16, i.e., coaxial with the front drive shaft 16. The front differential gear 20 is connected to the drive shaft 30 via a coupler 32. The front differential gear 20 distributes the power transmitted from the engine 24 via the drive shaft 30 to each axle of the front drive shaft 16, i.e., each axle of the front wheels 12, and is a differential gear mechanism for the front wheels that allows differential rotation of the left and right sides of the front wheels 12.

[0026] Coupler 32 is disposed in the power transmission path between driveshaft 30 and front differential gear 20. Coupler 32 is a known electronically controlled coupler, for example, composed of a wet multi-plate clutch, which controls the transmitted torque via electrical signals from an electronic control device (not shown) included in the all-wheel drive vehicle 10. By controlling the transmitted torque, coupler 32 can continuously change the torque distribution between the front and rear wheels, for example, between 0:100 and 50:50.

[0027] In the power transmission path between engine 24 and rear wheels 14, power from engine 24 is transmitted to rear wheels 14 sequentially via transmission 26, rear differential gear 22, and rear drive shaft 18. In the power transmission path between engine 24 and front wheels 12, power from engine 24 is transmitted to front wheels 12 sequentially via transmission 26, transfer case 28, drive shaft 30, coupler 32, front differential gear 20, and front drive shaft 16.

[0028] 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. The all-wheel drive vehicle 10 has two front wheels 12 and two rear wheels 14, and is therefore a four-wheel drive vehicle. In this embodiment, all-wheel drive (AWD) and four-wheel drive (4WD) have the same meaning. In addition to being able to drive under AWD control (AWD state also means the same thing) that drives both the front wheels 12 and the rear wheels 14, the all-wheel drive vehicle 10 can also drive under two-wheel drive (=2WD state also means the same thing) control (RWD state also means the same thing) that drives only the rear wheels 14.

[0029] In the all-wheel drive vehicle 10, the transfer case 28 can be positioned in front of the engine 24 in the forward and reverse directions. However, in the all-wheel drive vehicle 10 with its inherently small mid-engine layout, it is difficult to ensure sufficient living space in front of the engine 24. Furthermore, since the power transmission from the engine 24 via the transmission 26 needs to be separated between the rear differential gear 22 and the transfer case 28, it is not possible to directly connect the transfer case 28 to the rear differential housing 22c, which serves as the input rotating component of the rear differential gear 22. Therefore, additional components such as gears and shafts are required, potentially increasing cost or weight.

[0030] Therefore, in the all-wheel drive vehicle 10, the transfer case 28 is positioned rearward relative to the engine 24 in the forward and reverse directions. Furthermore, the transfer case 28 is directly connected to the rear differential housing 22c and is connected to the transmission 26 via the rear differential housing 22c.

[0031] Figure 2This is a partial cross-sectional view of the transfer case 28 or its vicinity, viewed from the left side in the vehicle width direction. The "vertical direction" in the figure refers to the vertical direction in the mounted state, i.e., the on-board state, on the all-wheel drive vehicle 10.

[0032] exist Figure 1 , Figure 2 In the middle, the transfer case 28 includes: a transfer case input component 50; a transfer case output component 60 connected to the transfer case input component 50; and a transfer case housing 80 that houses the transfer case input component 50 and the transfer case output component 60.

[0033] The transfer case input component 50 includes: a transfer case input shaft 52, one end of which is power-transmittably connected to the transmission 26; and a transfer case input gear 54, fixedly mounted on the other end of the transfer case input shaft 52. The transfer case input shaft 52 is a rotating shaft whose end is connected to the transmission 26 via an input rotating component of the rear differential gear 22. For example, the transfer case input shaft 52 is connected to the transmission 26 via an end connected to the rear differential housing 22c. The rear differential housing 22c is connected to the transmission 26 via a rear differential ring gear 22r integrally connected to the rear differential housing 22c. The rear differential ring gear 22r, like the rear differential housing 22c, functions as an input rotating component of the rear differential gear 22. The transfer case input shaft 52 and the rear differential gear 22 are arranged side-by-side on the axis CL2 of the rear drive shaft 18.

[0034] Furthermore, depending on the configuration position of the rear differential ring gear 22r, there is also a case where one end of the transfer case input shaft 52 is connected to the rear differential ring gear 22r and thus to the transmission 26. Moreover, "fixed" means the same as being fixed in a way that prevents relative rotation.

[0035] The transfer case output component 60 includes: a first transfer case output shaft 62; a transfer case output gear 64 fixedly disposed at one end of the first transfer case output shaft 62; a second transfer case output shaft 66 disposed parallel to the first transfer case output shaft 62; and a connecting component 70.

[0036] The first transfer case output shaft 62 is a rotating shaft extending from one end toward the rear in the forward / reverse direction to the other end. The transfer case output gear 64 is a gear that meshes with the transfer case input gear 54. For example, the transfer case input gear 54 and the transfer case output gear 64 are a gear pair that constitutes a hypoid gear. The transfer case output gear 64 is a hypoid pinion that forms a hypoid gear with the transfer case input gear 54.

[0037] The connecting component 70 connects the other end of the first transfer case output shaft 62 and one end of the second transfer case output shaft 66. The connecting component 70 includes a first gear 72, a second gear 74, and a transmission component 76. The first gear 72 is a gear fixedly disposed at the other end of the first transfer case output shaft 62. The second gear 74 is a gear fixedly disposed at one end of the second transfer case output shaft 66. The transmission component 76 is a component wound around the first gear 72 and the second gear 74. For example, the transmission component 76 is a chain or belt. In particular, the transmission component 76 is a silent chain.

[0038] The second transfer case output shaft 66 is a rotating shaft whose other end is connected to the drive shaft 30. The second transfer case output shaft 66 is positioned below or near the first transfer case output shaft 62 in the vertical direction when the vehicle is in the vehicle-mounted state. Thus, the second transfer case output shaft 66 is connected to the drive shaft 30 via the engine 24 in the vertical direction when the vehicle is in the vehicle-mounted state.

[0039] The transfer case housing 80 includes a gear housing 80a having a gear chamber Rg and a chain housing 80b having a chain chamber Rc. The gear chamber Rg is a hypoid gear chamber that houses the transfer case input gear 54 and the transfer case output gear 64, i.e., a hypoid gear. The chain chamber Rc is the connecting chamber of the present invention that houses the connecting member 70.

[0040] The transfer case housing 80 stores lubricating oil FLD. The lubricating oil FLD is, for example, oil used to lubricate hypoid gears (transfer input gear 54, transfer output gear 64) or connecting parts 70. The lubricating oil FLD is circulated in both the gear chamber Rg and the chain chamber Rc. In the all-wheel drive vehicle 10, the lubricating oil FLD is circulated from the chain chamber Rc to the gear chamber Rg by the force of the connecting parts 70 in the chain chamber Rc (refer to thick arrow A). Furthermore, in the all-wheel drive vehicle 10, the lubricating oil FLD is circulated from the gear chamber Rg to the chain chamber Rc by agitating the lubricating oil FLD in the gear chamber Rg or by increasing the oil volume in the gear chamber Rg (refer to thick arrow B). Therefore, in the all-wheel drive vehicle 10, an oil pump-free system can be implemented, enabling cost reduction or quality improvement.

[0041] The heat generated in the hypoid gears (transfer input gear 54, transfer case output gear 64) is greater than the heat generated in the connecting member 70 (i.e., chain-based heat generation). Alternatively, it is also possible to achieve the effect of cooling the lubricating oil FLD by scraping based on the connecting member 70. The lubricating oil FLD, heated in the gear chamber Rg by the heat generated in the hypoid gears, circulates to the chain chamber Rc and is cooled by scraping based on the connecting member 70. The lubricating oil FLD cooled in the chain chamber Rc circulates to the gear chamber Rg, cooling the hypoid gears by the lubricating oil FLD, thereby suppressing the heat generation of the hypoid gears.

[0042] Figures 3, 4, and 5 are schematic diagrams illustrating the connecting oil passages through which lubricating oil FLD flows. Figure 3(a) is an external view of the transfer case 28 viewed 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 housing 80b viewed from the gear chamber Rg side. Figure 3(c) is an external view of the transfer case housing 80 viewed 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 viewed from the chain chamber Rc side, with the connecting member 70 cut off. Figure 4(b) is an external view of the transfer case 28 viewed from the chain chamber Rc side, with the middle position of the first transfer case output shaft 62 cut off. Figure 5(a) is an external view of the transfer case 28 viewed from the rear left side in the vehicle width direction, with a portion cut off. Figure 5(b) is a perspective view of the chain housing 80b viewed from the gear chamber Rg side, with a portion of the chain chamber Rc side cut off.

[0043] In Figures 3-5, the transfer case 80 further includes a first connecting oil passage 82 and a second connecting oil passage 84. The first connecting oil passage 82 is an oil passage for allowing lubricating oil FLD to flow from the space above the chain chamber Rc in the vertical direction under vehicle loading conditions to the space above the gear chamber Rg in the vertical direction under vehicle loading conditions. The second connecting oil passage 84 is located further below or near the lower part of the first connecting oil passage 82 in the vertical direction under vehicle loading conditions. The second connecting oil passage 84 is an oil passage for allowing lubricating oil FLD to flow from the gear chamber Rg to the chain chamber Rc. The first connecting oil passage 82 includes an inflow oil passage 82a, an upper intermediate chamber 82b, and an inlet oil passage 82c. In the first connecting oil passage 82, lubricating oil FLD flows sequentially into the inflow oil passage 82a, the upper intermediate chamber 82b, and the inlet oil passage 82c. The second connecting oil passage 84 includes an outflow oil passage 84a, a lower intermediate chamber 84b, and an outlet oil passage 84c. In the second connecting oil passage 84, the lubricating oil FLD flows sequentially into the outlet oil passage 84c, the lower intermediate chamber 84b, and the outlet oil passage 84a (refer to the thick arrow C in (a) of Figure 5).

[0044] 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 may have ribs protruding from the upper surface of the inner wall of the chain housing 80b in the vertical direction when in vehicle mode. The ribs of the inflow oil passage 82a serve to scrape off the lubricating oil FLD scraped off by the connecting member 70. The inflow oil passage 82a may also have a tray integrally formed with the ribs to receive the lubricating oil FLD scraped off by the ribs. The inflow oil passage 82a communicates with the upper intermediate chamber 82b, for example, at an angle such that the lubricating oil FLD flows into the upper intermediate chamber 82b when in vehicle mode. In this embodiment, two inflow oil passages 82a are provided.

[0045] The upper intermediate chamber 82b is a small chamber located between the inflow oil passage 82a and the inlet oil passage 82c, allowing lubricating oil FLD from the inflow oil passage 82a to flow into the inlet oil passage 82c (refer to the thick arrow D in Figure 4(b)). The upper intermediate chamber 82b connects the inflow oil passage 82a and the inlet oil passage 82c. Depending on the shape of the upper intermediate chamber 82b, the flow rate of lubricating oil FLD in the first connecting oil passage 82 can be pre-designed or experimentally adjusted. In the transfer case housing 80, the circulation rate of lubricating oil FLD is pre-determined based on the rotational speed of the connecting component 70 or the temperature of the lubricating oil FLD, depending on the size of the inflow oil passage 82a or the upper intermediate chamber 82b.

[0046] The oil inlet passage 82c is an oil passage that introduces lubricating oil FLD into the space above the gear chamber Rg. For example, the oil inlet passage 82c is a connecting hole formed in the gear housing 80a that connects the upper intermediate chamber 82b and the space above the gear chamber Rg. The oil inlet passage 82c is inclined, for example, so that in the vehicle-mounted state, the lubricating oil FLD flows from the upper intermediate chamber 82b to the space above the gear chamber Rg.

[0047] Oil outlet passage 84a is an oil passage through which lubricating oil FLD flows to the chain chamber Rc. Multiple oil outlet passages 84a are formed, for example, on the radially outer periphery of the first transfer case output shaft 62 in the side wall of the chain housing 80b on the gear housing 80a side, and vertically downwards in the vehicle-mounted state. Oil outlet passages 84a communicate with the lower intermediate chamber 84b.

[0048] The lower intermediate chamber 84b is a small chamber located between the outflow oil passage 84a and the outlet oil passage 84c, allowing lubricating oil FLD from the outlet oil passage 84c to flow into the outflow oil passage 84a. The lower intermediate chamber 84b connects the outflow oil passage 84a and the outlet oil passage 84c. Depending on the shape of the lower intermediate chamber 84b, the flow rate of the lubricating oil FLD in the second connecting oil passage 84 can be pre-designed or experimentally adjusted. Within the transfer case housing 80, the circulation rate of the lubricating oil FLD, based on the rotational speed of the connecting component 70 or the temperature of the lubricating oil FLD, is pre-determined according to the size of the outflow oil passage 84a or the lower intermediate chamber 84b.

[0049] Oil outlet passage 84c is an oil passage that introduces lubricating oil FLD from gear chamber Rg to chain chamber Rc. Oil outlet passage 84c is, for example, an oil passage connecting gear chamber Rg and lower intermediate chamber 84b. That is, oil outlet passage 84c is an oil passage that introduces lubricating oil FLD from gear chamber Rg to lower intermediate chamber 84b. Oil outlet passage 84c is, for example, formed by the internal space (clearance) of the bearing 90 that supports the first transfer case output shaft 62 in gear housing 80a, as provided in the all-wheel drive vehicle 10.

[0050] Here, Figure 2The dashed line E shown represents the specified oil level H of the gear chamber Rg in the vertical direction under vehicle-mounted conditions. The specified oil level H is, for example, a predetermined oil level (assumed oil level) of the gear chamber Rg to ensure proper lubrication or cooling of the hypoid gears (transferor input gear 54, transferor output gear 64). When 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 more than required. Therefore, to prevent or suppress excessive lubricating oil FLD in the gear chamber Rg, the second connecting oil passage 84 also includes a second outlet oil passage 84d. The amount of lubricating oil FLD in the gear chamber Rg that exceeds the specified oil level H circulates primarily from the gear chamber Rg to the chain chamber Rc via the second outlet oil passage 84d.

[0051] Figure 6 is a schematic diagram illustrating the second outgoing oil passage 84d. Figure 6(a) is an external view of the gear housing 80a viewed from the chain chamber Rc side. Figure 6(b) is an external view of the transfer case 28 viewed from the rear left side in the vehicle width direction, with a portion cut off.

[0052] In Figure 6, the second oil outlet passage 84d is a different oil outlet passage from the oil outlet passage 84c (refer to Figures 3 and 5) that introduces the lubricating oil FLD from the gear chamber Rg into the lower intermediate chamber 84b. The second oil outlet passage 84d is located at a position higher than the specified oil level H of the gear chamber Rg. For example, the second oil outlet passage 84d is a connecting hole in the gear housing 80a, formed by a concave inner surface of the bearing 90, that connects the gear chamber Rg and the lower intermediate chamber 84b.

[0053] As described above, according to this embodiment, the transfer case 28 includes a transfer case housing 80, which houses a transfer case input component 50 and a transfer case output component 60 storing lubricating oil FLD. The transfer case housing 80 includes: a gear chamber Rg housing a transfer case input gear 54 and a transfer case output gear 64; a chain chamber Rc housing a connecting component 70; a first connecting oil passage 82; and a second connecting oil passage 84, disposed below or near below the first connecting oil passage 82 in the vertical direction under vehicle loading conditions. The first connecting oil passage 82 allows lubricating oil FLD to flow from the space above the chain chamber Rc in the vertical direction under vehicle loading conditions to the space above the gear chamber Rg in the vertical direction under vehicle loading conditions. The second connecting oil passage 84 allows lubricating oil FLD to flow from the gear chamber Rg to the chain chamber Rc. Therefore, the lubricating oil FLD is cooled by the connecting part 70 that scrapes it in the chain chamber Rc, and the scraped lubricating oil FLD circulates from the chain chamber Rc to the gear chamber Rg via the first connecting oil passage 82. Furthermore, in the gear chamber Rg, the lubricating oil FLD efficiently lubricates the meshing transfer case input gear 54 and transfer case output gear 64, thereby suppressing heat generation. The lubricating oil FLD that lubricates the transfer case input gear 54 and transfer case output gear 64 circulates from the gear chamber Rg to the chain chamber Rc via the second connecting oil passage 84. Therefore, in the all-wheel drive vehicle 10 with a transversely mounted engine 24, heat generation of the transfer case 28 is easily suppressed.

[0054] Furthermore, according to this embodiment, the transfer case input gear 54 and the transfer case output gear 64 are a gear pair constituting a hypoid gear. The connecting member 70 includes: a first gear 72, fixedly disposed at the other end of the first transfer case output shaft 62; a second gear 74, fixedly disposed at one end of the second transfer case output shaft 66; and a transmission member 76, wound around the first gear 72 and the second gear 74. This simplifies, for example, the structure of scraping lubricating oil FLD stored in the lower part of the housing containing the connecting member 70 in the vertical direction during vehicle operation from below to above. Furthermore, during vehicle operation, since the heat generated by the connecting member 70, including the transmission member 76 as a chain or belt, is less than that of the hypoid gear, the lubricating oil FLD cooled in the chain chamber Rc circulates to the gear chamber Rg, thereby efficiently suppressing the heat generation of the hypoid gear.

[0055] Furthermore, according to this embodiment, the first connecting oil passage 82 includes an inflow oil passage 82a, an upper intermediate chamber 82b, and an inlet oil passage 82c. The second connecting oil passage 84 includes an outflow oil passage 84a, a lower intermediate chamber 84b, and an outlet oil passage 84c. Therefore, the flow rate of the lubricating oil FLD in the first connecting oil passage 82 or the second connecting oil passage 84 can be pre-adjusted according to the shape of the upper intermediate chamber 82b or the lower intermediate chamber 84b.

[0056] Furthermore, according to this embodiment, the second connecting oil passage 84 also includes a second outlet oil passage 84d. Thus, lubricating oil FLD in the gear chamber Rg that exceeds a predetermined oil level H mainly circulates to the chain chamber Rc via the second outlet oil passage 84d, thereby preventing or suppressing excessive amounts of lubricating oil FLD in the gear chamber Rg.

[0057] Furthermore, according to this embodiment, the axis CL1 of the engine output shaft 24a is configured as a transversely mounted engine 24 in the vehicle width direction, positioned near the rear drive shaft 18 in the forward / reverse direction. A 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 axle of the rear drive shaft 18. The transfer case 28 distributes the power from the engine 24 transmitted via the transmission 26 to the front wheels 12. The drive shaft 30 transmits the power from the engine 24 transmitted via the transfer case 28 to the front drive shaft 16.

[0058] The front differential gear 20 distributes the power from the engine 24, transmitted via the drive shaft 30, to each axle of the front drive shaft 16. The transfer case 28 is positioned rearward relative to the engine 24 in the forward and reverse directions. Thus, in the all-wheel drive vehicle 10 with a structure in which the transversely mounted engine 24 is positioned near the rear drive shaft 18, sufficient living space in front of the engine 24 in the forward and reverse directions is easily ensured.

[0059] Furthermore, according to this embodiment, one end of the transfer case input shaft 52 is connected to the transmission 26 via the input rotating component (rear differential housing 22c, rear differential ring gear 22r) of the rear differential gear 22, and is arranged parallel to the rear differential gear 22 on the same axis as the rear drive shaft 18. Therefore, the transfer case 28 can be directly connected to the rear differential housing 22c without the need for additional components such as gears and shafts, thus suppressing increases in cost or weight.

[0060] Furthermore, according to this embodiment, the first transfer case output shaft 62 extends from one end toward the rear in the forward / reverse direction to the other end, and the other end of the second transfer case output shaft 66 is connected to the drive shaft 30. Thus, in the configuration where the transfer case 28 is positioned rearward relative to the engine 24 in the forward / reverse direction, the transfer case 28 is able to appropriately distribute the power from the engine 24 transmitted via the transmission 26 to the front wheels 12.

[0061] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is also applicable to other methods.

[0062] For example, in the aforementioned embodiment, the connecting member 70 can be structured as follows: it has a gear fixedly disposed at the other end of the first transfer case output shaft 62 and a gear fixedly disposed at one end of the second transfer case output shaft 66, and these gears mesh directly or via a counting gear. Even so, by scraping the lubricating oil FLD by the connecting member 70, a certain effect can be achieved in easily suppressing the heat generation of the transfer case 28.

[0063] Furthermore, in the foregoing embodiments, the power source may be, for example, an electric motor or something other than the engine 24. When the power source is solely an electric motor, the power transmission unit may be, for example, a gear mechanism with a single gear ratio instead of the transmission 26.

[0064] Furthermore, in the aforementioned embodiment, the first transfer case output shaft 62 is a rotating shaft extending rearward in the forward / reverse direction from one end to the other end. However, depending on the structure or configuration of the transfer case 28, it may also be a rotating shaft extending forward in the forward / reverse direction from one end to the other end. The transfer case 28 is not limited to a configuration on the rear wheel 14 side, for example, and may also be configured on the front wheel 12 side. Therefore, the power source is not limited to a mid-mounted layout.

[0065] Furthermore, in the aforementioned embodiments, the coupler 32 may, for example, be disposed in the power transmission path between the front differential gear 20 and the front drive shaft 16. Alternatively, the coupler 32 may also be replaced by, for example, a clutch that connects or disconnects the power transmission path, a center differential device that allows differential rotation between the front wheels 12 and the rear wheels 14, or the like. That is, the coupler 32 may also be replaced by a different mechanism than the coupler 32, which is combined with the transfer case 28 to enable AWD driving.

[0066] Furthermore, the above is only one embodiment, and the present invention can be implemented with various changes and improvements based on the knowledge of those skilled in the art.

[0067] Symbol Explanation

[0068] 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 housing (input rotating part of the rear differential gear); 22r - Rear differential ring gear (input rotating part of the rear differential gear); 24 - Engine (power source); 24a - Engine output shaft (power source output shaft); 26 - Transmission (power transmission part); 28 - Transfer case; 30 - Transmission Drive shaft, 50-Transferor input component, 52-Transferor input shaft, 54-Transferor input gear, 60-Transferor output component, 62-First transferor output shaft, 64-Transferor output gear, 66-Second transferor output shaft, 70-Connecting component, 72-First gear, 74-Second gear, 76-Transmission component, 80-Transferor housing, 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-Outflow oil passage, 84d-Second outflow 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 output shaft axis oriented in the vehicle width direction; A power transmission unit, which is disposed coaxially with the output shaft of the power source and transmits power from the power source; and A transfer case that distributes power from the power source, transmitted via the power transmission unit, to the front wheels and the rear wheels. The all-wheel drive vehicle is characterized by the following: The transfer case includes: Transfer case input components; The transfer case output component is connected to the transfer case input component; and The transfer case housing stores lubricating oil and houses the transfer case input and the transfer case output components. The transfer case input component includes: The transfer case input shaft, one end of which is power-transmittably connected to the power transmission unit; and The transfer case input gear is fixedly mounted at the other end of the transfer case input shaft. The transfer case output component includes: The first transfer case output shaft extends from one end to the other. The transfer case output gear is fixedly mounted at one end of the first transfer case output shaft and meshes with the transfer case input gear. The second transfer case output shaft is arranged parallel to the first transfer case output shaft in the vertical direction, either below or near the first transfer case output shaft in the vehicle-mounted state; and A connecting component that connects one end of the output shaft of the first transfer case to one end of the output shaft of the second transfer case. The transfer case housing includes: A gear chamber that houses the transfer case input gear and the transfer case output gear; A connection chamber that houses the connecting components; The first connecting oil passage allows the lubricating oil to flow from the space above the connecting chamber in the vertical direction to the space above the gear chamber in the vertical direction; and The second connecting oil passage is located below or near the lower part of the vertical direction than the first connecting oil passage, allowing the lubricating oil to flow from the gear chamber to the connecting chamber.

2. The all-wheel drive vehicle according to claim 1, characterized in that, The transfer case input gear and the transfer case output gear are gear pairs that form a hypoid gear. The connecting component includes: The first gear is fixedly mounted on the other end of the output shaft of the first transfer case; The second gear is fixedly mounted on one end of the output shaft of the second transfer case; and A transmission component, which is wound around the first gear and the second gear.

3. The all-wheel drive vehicle according to claim 1, characterized in that, The first connecting oil circuit includes: The lubricating oil flows into the oil passage, causing it to flow in from the space above the connecting chamber. An oil inlet passage introduces the lubricating oil into the space above the gear chamber; and The upper middle chamber allows the lubricating oil from the inflow oil passage to flow into the inlet oil passage. The second connecting oil circuit includes: An oil outlet passage leads the lubricating oil from the gear chamber into the connecting chamber; The oil passage allows the lubricating oil to flow out into the connecting chamber; and The lower middle chamber 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 circuit also includes: The second oil outlet is located at a position higher than the specified oil level of the gear chamber in the vertical direction, and introduces the lubricating oil of the gear chamber into the lower intermediate chamber.

5. The all-wheel drive vehicle according to any one of claims 1 to 4, characterized in that, It also has: Left and right front drive shafts, which respectively drive the front wheels; Left and right rear drive shafts, which respectively drive the rear wheels; A rear differential gear, which is arranged coaxially with the rear drive shaft, distributes the power from the power source transmitted via the power transmission unit to each of the rear drive shafts; A drive shaft that transmits power from the power source via the transfer case to the front drive shaft; and A front differential gear, which is mounted coaxially with the front drive shaft, distributes power from the power source transmitted via the drive shaft to each of the front drive shafts. The power source is a transversely mounted engine located near the rear drive shaft in the forward / reverse direction, with the engine output shaft centered in the vehicle width direction. The power transmission unit is a gearbox that is mounted on the same axis as the engine output shaft and transmits power from the engine. The transfer case is positioned rearward relative to the engine in the forward / reverse direction. One end of the transfer case input shaft is connected to the transmission via the input rotation component of the rear differential gear, and is arranged parallel to the rear differential gear on the same axis as the rear drive shaft. The first transfer case output shaft extends from one end toward the rear in the forward / reverse direction to the other end. The other end of the output shaft of the second transfer case is connected to the drive shaft.

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