Lubricating device for vehicle transfer

Abstract

To provide a lubricating device of a transfer for a vehicle capable of suppressing insufficient lubrication of an oil seal between a main shaft and a transfer case during uphill traveling of the vehicle during two wheel drive traveling.SOLUTION: During running of the hybrid vehicle 10 on a 2WD, when the hybrid vehicle 10 is running on an uphill road on which the oil strainer 74 is exposed from the surface of the oil in the oil storage space (uphill gradient Slo> θ 1), the chain connecting / disconnecting portion 58 is engaged to rotate the chain 56, so that the oil scooped up by the rotation of the chain 56 is supplied to the oil seal 72. As a result, insufficient lubrication of the oil seal 72 between the rear-wheel side shaft 44 and the transfer 22 is suppressed when the hybrid vehicle 10 is traveling uphill while traveling on a 2WD.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a lubrication device for a vehicle transfer that transmits power output from a power source to rear wheels when the vehicle is in two-wheel drive mode, and transmits part of the power output from the power source to front wheels when the vehicle is in four-wheel drive mode. [Background technology]

[0002] A known vehicle transfer case houses a main shaft that transmits power to main drive wheels, a counter shaft that is arranged parallel to the main shaft and transmits power to counter drive wheels, a power transmission belt wound around a main shaft sprocket on the main shaft and a counter shaft sprocket on the counter shaft, and a dog clutch that connects and disconnects the main shaft sprocket and the main shaft. In this vehicle transfer case, oil in an oil storage space located at the bottom of the transfer case is sucked into an oil strainer that functions as an intake port and is pumped by an oil pump located in the transfer case to the front end of the main shaft, where it is passed through an oil hole in the main shaft to lubricate various components on the main shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-032763 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because the oil strainer is fixed in an oil storage space located at the bottom of the transfer case, further forward than the countershaft sprocket, when a two-wheel drive vehicle starts climbing a slope and the oil level in the oil storage space tilts, the oil strainer becomes exposed to the oil surface, reducing the amount of oil suction and resulting in an insufficient amount of oil supplied from the oil pump. This causes a problem of insufficient lubrication for components located at the rear end of the mainshaft (hereinafter referred to as the rear end). In particular, the durability of the oil seal located at the rear end of the mainshaft to prevent oil leakage between the mainshaft and the transfer case can be reduced due to insufficient lubrication.

[0005] The present invention was made against the background of the above circumstances, and its purpose is to provide a lubrication device for a vehicle transfer case that prevents insufficient lubrication of the oil seal between the main shaft and the transfer case when the vehicle is traveling uphill in two-wheel drive mode. [Means for solving the problem]

[0006] The gist of the present invention is a transfer case comprising: (a) a main shaft for transmitting power to main drive wheels; a counter shaft provided below the main shaft in parallel with the main shaft for transmitting power to counter drive wheels; a transmission belt wound around a main shaft sprocket provided on the main shaft and a counter shaft sprocket provided on the counter shaft; a dog clutch for connecting and disconnecting the main shaft sprocket and the main shaft; and an oil seal provided at the rearmost end of the main shaft to prevent oil leakage between the main shaft and the transfer case, and an oil reservoir provided at the bottom of the transfer case. A lubrication device for a vehicle transfer in which oil is sucked into the space by an oil strainer fixed at a position further forward of the countershaft sprocket and pressure-fed into the front end of the main shaft, and lubrication of each part attached to the main shaft is performed from inside the main shaft through an oil hole, (b) when the vehicle is traveling in two-wheel drive using the main drive wheels and traveling uphill such that the oil strainer is exposed above the oil surface in the oil storage space, the mesh clutch is engaged and oil scooped up by the rotation of the transmission belt is supplied to the oil seal. [Effects of the Invention]

[0007] With this vehicle transfer case lubrication system, when the vehicle is traveling in two-wheel drive mode using the main drive wheels and traveling uphill, causing the oil strainer to be exposed above the oil level in the oil storage space, the dog clutch is engaged and the transmission belt is rotated, so that oil scooped up by the rotation of the transmission belt is supplied to the oil seal. This prevents insufficient lubrication of the oil seal between the main shaft and the transfer case when the vehicle is traveling uphill in two-wheel drive mode. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of a schematic configuration of a vehicle to which the present invention is applied; [Figure 2] FIG. 2 is a diagram illustrating an oil lubrication structure within a transfer case. [Figure 3] 3 is a flowchart illustrating a main part of the control operation of the electronic control device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0010] FIG. 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied. The vehicle 10 is equipped with an engine 12 as a power source, front wheels 14, rear wheels 16, a power transmission device 18 that transmits the power of the engine 12 to the front wheels 14 and rear wheels 16, and the like. The rear wheels 16 are main drive wheels that serve as drive wheels in both two-wheel drive (2WD) and four-wheel drive (4WD) driving. The front wheels 14 are auxiliary drive wheels that serve as driven wheels in 2WD driving and drive wheels in 4WD driving. The vehicle 10 is a 4WD vehicle based on a front-engine, rear-wheel drive (FR) system.

[0011] The power transmission device 18 includes a transmission 20 connected to the engine 12, a transfer case 22 connected to the transmission 20, and a front propeller shaft 24 and a rear propeller shaft 26 connected to the transfer case 22, respectively. A front differential 28 and a front drive shaft 32 are connected to the front propeller shaft 24, and a rear differential 30 and a rear drive shaft 34 are connected to the rear propeller shaft 26, in that order. The transfer case 22 is a driving force distribution device that distributes the power of the engine 12 to the front wheels 14.

[0012] The front differential 28 includes a differential ring gear 28a, a differential case 28b, differential side gears 28c, differential pinions 28d, pinion shafts 28e, and a differential internal power disconnecting / connecting mechanism (hereinafter referred to as a differential internal disconnecting mechanism) 36 and the like.

[0013] The differential-internal type disconnecting mechanism 36 is a dog clutch (i.e., a dog clutch) that selectively connects or disconnects, i.e., disconnects, the power transmission path between the differential case 28b and the pinion support member 28f (i.e., between the front propeller shaft 24 and the front wheels 14). The front wheel disconnecting actuator 38 is controlled by an electronic control unit 80, which will be described later, to switch between connection and disconnection of the differential-internal type disconnecting mechanism 36.

[0014] A cross-sectional view illustrating the schematic configuration of the transfer case 22 is shown in a speech bubble in Figure 1. The transfer case 22 includes a transfer case (hereinafter simply referred to as the case) 40 that houses various components. The transfer case 22 includes, within the case 40, an input shaft 42, a rear-wheel output shaft 44, a drive gear 46, a lock gear 48 connected to the drive gear 46 so as not to rotate relative to the drive gear 46, a high / low switching unit 50 that changes the speed of the input shaft 42 and transmits it to the rear-wheel output shaft 44, and a chain connecting / disconnecting unit 58 that connects / disconnects the drive gear 46 and the rear-wheel output shaft 44, all of which are arranged around a common axis C1. The transfer case 22 also includes a front-wheel output shaft 52 that is arranged parallel to the rear-wheel output shaft 44 below the rear-wheel output shaft 44 within the case 40, and a driven gear 54 that is integral with the front-wheel output shaft 52, all of which are arranged around a common axis C2. The transfer 22 is equipped with a chain 56 that is wound around the drive gear 46 and the driven gear 54 and connects the drive gear 46 and the driven gear 54. The rear wheel output shaft 44, the front wheel output shaft 52, the drive gear 46, the driven gear 54, the chain 56, and the chain connecting / disconnecting portion 58 correspond to the "main shaft," "counter shaft," "main shaft sprocket," "counter shaft sprocket," "transmission belt," and "mesh clutch" in the present invention, respectively.

[0015] The transfer case 22 also includes an oil lubrication mechanism 70 for oil lubrication within the transfer case 22. The transfer case 22 also includes an oil seal 72 provided at the rearmost end of the rear-wheel-side output shaft 44 to prevent oil leakage between the rear-wheel-side output shaft 44 and the case 40, and an oil strainer 74 fixed to an oil storage space provided at the bottom of the case 40 at a position further forward of the driven gear 54 to suck oil.

[0016] The input shaft 42 is connected to the transmission 20. The rear-wheel output shaft 44 is connected to the rear propeller shaft 26 and is a main driving force transmission shaft that transmits the power of the engine 12 to the rear wheels 16. The drive gear 46 is provided so as to be rotatable relative to the rear-wheel output shaft 44. The front-wheel output shaft 52 is connected to the front propeller shaft 24 and is an auxiliary driving force transmission shaft that transmits a portion of the power of the engine 12 distributed by the transfer 22 to the front wheels 14. The front propeller shaft 24 also functions as an auxiliary driving force transmission shaft.

[0017] The high / low switching unit 50 is an auxiliary transmission equipped with a known planetary gear set and a mesh clutch. A cylindrical high / low switching sleeve 50a, which is provided on the rear-wheel output shaft 44 so as not to rotate about the axis C1 relative to the rear-wheel output shaft 44, moves in the direction of the axis C1 to switch the connection destination with the planetary gear set, thereby switching between high gear Hg (connected to the sun gear S: as shown in the drawing) and low gear Lg (connected to the carrier C).

[0018] The chain connecting / disconnecting unit 58 switches between connecting and disconnecting the rear wheel side output shaft 44 and the drive gear 46. A cylindrical chain connecting / disconnecting sleeve 58a, which is provided on the rear wheel side output shaft 44 so as not to rotate relative to the rear wheel side output shaft 44 about the axis C1, has inner teeth 58b which move in the direction of the axis C1 to mesh with the lock gear 48, thereby engaging the rear wheel side output shaft 44 and the drive gear 46. When the chain connecting / disconnecting unit 58 is in the engaged state, the transfer 22 causes the rear wheel side output shaft 44 and the drive gear 46 to rotate integrally.

[0019] The transfer 22 is equipped with a TF actuator 60 as a device for actuating the high / low switching unit 50 and the chain disconnecting unit 58. Operation of the TF actuator 60 causes the high / low operating member 62 to move the high / low switching sleeve 50a, and the chain operating member 64 to move the chain disconnecting sleeve 58a, thereby switching between the high gear position Hg and the low gear position Lg, and switching between the disengaged and engaged states of the chain disconnecting unit 58.

[0020] When the chain disconnecting section 58 is in the released state (as shown on the paper), the power transmitted from the transmission 20 is transmitted only to the rear propeller shaft 26, with the power transmission path between the rear wheel output shaft 44 and the drive gear 46 being cut off, and when the chain disconnecting section 58 is in the engaged state, the power is transmitted to both the front propeller shaft 24 and the rear propeller shaft 26.

[0021] The vehicle 10 can be selectively switched between a 2WD state in which the power of the engine 12 is transmitted to the rear wheels 16 by disengaging both the chain connection / disconnection unit 58 and the differential internal type disconnection mechanism 36, and a 4WD state in which the power of the engine 12 is transmitted to the rear wheels 16 and the front wheels 14 by engaging both the chain connection / disconnection unit 58 and the differential internal type disconnection mechanism 36.

[0022] The vehicle 10 is equipped with an electronic control device 80 as a control device for the vehicle 10. The electronic control device 80 is configured to include a so-called microcomputer. The electronic control device 80 and the oil lubrication mechanism 70 correspond to the "lubrication device" in the present invention.

[0023] The electronic control unit 80 is supplied with various signals (e.g., the longitudinal acceleration G of the vehicle 10, the vehicle weight WTv that is the weight of the vehicle 10, and a 4WD driving selection signal 4WDon input by the driver) based on detection values ​​from various sensors (e.g., a G sensor 82, a vehicle weight sensor 84, a 4WD selection switch 86, etc.) provided on the vehicle 10. In addition, the electronic control unit 80 outputs various command signals (e.g., a differential disconnection operation command signal Sd for switching the state of the differential internal-type disconnection mechanism 36, and a TF operation command signal Sa for controlling the operation of the TF actuator 60 that switches the state of the high / low switching unit 50 and the chain disconnection unit 58) to each device (e.g., the front wheel connecting / disconnecting actuator 38, the TF actuator 60, etc.) provided on the vehicle 10.

[0024] 2 is a diagram illustrating the oil lubrication structure within the transfer case 22. Fig. 2(a) shows the state of the vehicle 10 when traveling on a flat road in 2WD mode. Oil that has accumulated up to the oil level shown in Fig. 2(a) in the oil storage space provided in the lower part of the case 40 is sucked up by the oil strainer 74 and pumped by an oil pump (not shown) of the oil lubrication mechanism 70 into the front end of the rear-wheel-side output shaft 44 along the path indicated by the thick line in the figure, and the oil is then lubricated from the rear-wheel-side output shaft 44 through oil holes (not shown) to lubricate the various components provided on the rear-wheel-side output shaft 44.

[0025] FIG. 2(b) shows the vehicle 10 in 2WD mode traveling uphill. When traveling uphill, the vehicle 10 tilts, causing the oil level in the oil storage space of the transfer 22 to tilt relative to the oil level, as shown in FIG. 2(b). This causes the oil strainer 74 to be exposed to the oil surface, reducing the amount of oil suction and resulting in an insufficient amount of oil supplied from the oil pump. This has resulted in a problem of insufficient lubrication of components located at the rear end of the rear-wheel output shaft 44. In particular, insufficient lubrication of the oil seal 72, located at the rearmost end of the rear-wheel output shaft 44 to prevent oil leakage between the rear-wheel output shaft 44 and the transfer case 40, could reduce its durability.

[0026] Therefore, when traveling uphill during 2WD driving, where the oil strainer 74 is exposed above the oil surface and insufficient lubrication of the oil seal 72 may occur, the electronic control device 80 performs a control operation to engage the chain connecting / disconnecting unit 58, thereby supplying oil scooped up by the rotation of the chain 56 from the oil retention space to the oil seal 72. As shown by the thick arrows in the speech bubble in Figure 2(b), the oil scooped up by the rotation of the chain 56 is supplied to the oil seal 72 through holes h1 and h2 newly provided in the case 40. Furthermore, although the chain connecting / disconnecting unit 58 is engaged, the differential-internal connecting / disconnecting mechanism 36 is in a disconnected state, so the vehicle 10 maintains 2WD driving.

[0027] FIG. 3 is a flowchart illustrating the control operation of the electronic control device 80 for oil lubrication of the transfer case 22 during 2WD driving, and is executed repeatedly during 2WD driving, for example.

[0028] 3, first, in step (hereinafter, "step" will be omitted) S10, it is determined whether the uphill gradient Slo during travel exceeds a threshold value θ1. The uphill gradient Slo can be determined, for example, by applying the flat road acceleration A calculated by dividing the drive torque during travel by the vehicle weight WTv and the longitudinal acceleration G of the vehicle 10 actually detected by the G sensor 82 to a preset gradient calculation map. The threshold value θ1 is set in advance by design or experimentation as an appropriate value for determining that the oil strainer 74 is exposed above the oil surface in the oil storage space and that insufficient lubrication of the oil seal 72 may occur.

[0029] If the determination in S10 is positive, i.e., if the vehicle is traveling uphill and the gradient exceeds the threshold θ1, then in S20 it is determined whether the chain connecting / disconnecting unit 58 is engaged. If the determination in S20 is negative, then in S30 the TF actuator 60 is operated to engage the chain connecting / disconnecting unit 58, and the routine is terminated. As a result, the chain connecting / disconnecting unit 58 is engaged, and oil scooped up by the rotation of the chain 56 is supplied to the oil seal 72. If the determination in S20 is positive, then in S40 the TF actuator 60 is stopped, and the routine is terminated.

[0030] If the determination in S10 is negative, i.e., if the vehicle is not traveling uphill with a slope exceeding the threshold θ1, then in S50 it is determined whether the chain connecting / disconnecting unit 58 is in the disengaged state. If the determination in S50 is negative, then in S60 the TF actuator 60 is operated so that the chain connecting / disconnecting unit 58 is in the disengaged state, and this routine is terminated. If the determination in S50 is positive, then the process proceeds to S40, where the TF actuator 60 is stopped, and this routine is terminated.

[0031] As described above, according to this embodiment, when the vehicle 10 is traveling in 2WD mode and traveling uphill (uphill gradient Slo>threshold θ1) and the oil strainer 74 is exposed above the oil level in the oil storage space, the chain disconnecting portion 58 is engaged and the chain 56 is rotated, so that oil scooped up by the rotation of the chain 56 is supplied to the oil seal 72. This prevents insufficient lubrication of the oil seal 72 between the rear wheel output shaft 44 and the transfer case 22 when the vehicle 10 is traveling uphill in 2WD mode.

[0032] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0033] For example, in the above-described embodiment, the dog clutch that connects and disconnects the power transmission path between the front propeller shaft 24 and the front wheels 14 may be an external differential power disconnect / connect mechanism instead of the internal differential disconnect mechanism 36.

[0034] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0035] 10: Vehicle 14: Front wheels (auxiliary drive wheels) 16: Rear wheels (main drive wheels) 22: Transfer 40: Case (transfer case) 44: Rear wheel side output shaft (main shaft) 46: Drive gear (main shaft sprocket) 52: Front wheel side output shaft (auxiliary shaft) 54: Driven gear (auxiliary shaft sprocket) 56: Chain (transmission belt) 58: Chain disconnection part (dog clutch) 70: Oil lubrication mechanism (lubrication device) 72: Oil seal 74: Oil strainer 80: Electronic control device (lubrication device)

Claims

[Claim 1] a transfer case that houses a main shaft that transmits power to main drive wheels; a counter shaft that is provided below the main shaft and parallel to the main shaft and transmits power to counter drive wheels; a transmission belt that is wound around a main shaft sprocket provided on the main shaft and a counter shaft sprocket provided on the counter shaft; a dog clutch that connects and disconnects the main shaft sprocket and the main shaft; and an oil seal provided at the rearmost end of the main shaft to prevent oil leakage between the main shaft and the transfer case, wherein oil is sucked into an oil storage space provided at a lower part of the transfer case by an oil strainer fixed at a position further forward of the counter shaft sprocket, and is pressure-fed into the vehicle front end of the main shaft, and various parts provided on the main shaft are lubricated from inside the main shaft through oil holes, When the vehicle is traveling in two-wheel drive mode using the main drive wheels and traveling uphill, where the oil strainer is exposed above the oil surface in the oil storage space, the mesh clutch is engaged, and oil scooped up by the rotation of the transmission belt is supplied to the oil seal. A lubricating device for a vehicle transfer case, comprising:

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