Lubricating device of transfer case for vehicle

Abstract

The invention provides a lubricating device of a transfer case for a vehicle. The lubricating device can restrain insufficient lubrication of an oil seal between a main shaft and the transfer case when a vehicle in two-wheel drive running climbs. During 2WD travel of the vehicle (10), when the oil filter (74) is exposed from the oil surface of the oil in the oil storage space, climbing travel (climbing slope Slogt; when a threshold value ([theta] 1) is greater than a threshold value ([theta] 1), the chain (56) is rotated by engaging the chain disconnecting part (58), and thus oil stirred 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 output shaft (44) and the transfer case (22) can be suppressed during climbing travel of the vehicle (10) during 2WD travel.

Description

Technical Field

[0001] The present invention relates to a lubrication device for a vehicle transfer case, which transmits power from a power source to the rear wheels in a two-wheel drive state and transmits a portion of the power from the power source to the front wheels in a four-wheel drive state. Background Technology

[0002] A known vehicle transfer case includes a main shaft that transmits power to the main drive wheel, a secondary shaft that is parallel to the main shaft and transmits power to the auxiliary drive wheel, a drive belt wound around a main shaft sprocket on the main shaft and a secondary shaft sprocket on the secondary shaft, and a clutch that disconnects the main shaft sprocket from the main shaft. In this transfer case, oil in a reservoir located in the lower part of the transfer case is drawn in by an oil filter that functions as a suction inlet, and is pumped into the front end of the main shaft by an oil pump located in the transfer case, lubricating the components of the main shaft through oil holes.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-032763 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, because the aforementioned oil filter is fixed in the lower oil reservoir within the transfer case, positioned closer to the front of the vehicle than the secondary shaft sprocket, when the two-wheel-drive vehicle is climbing an incline and the oil level in the reservoir tilts, the oil filter becomes exposed above the oil surface, reducing oil suction and resulting in insufficient oil supply from the oil pump. Therefore, there is a problem of insufficient lubrication of components located at the rear end of the main shaft (hereinafter referred to as the rear end). In particular, the durability of the oil seal located at the very rear of the main shaft, which is installed to prevent oil leakage between the main shaft and the transfer case, may be reduced due to insufficient lubrication.

[0008] The present invention was made against the background described above, and its purpose is to provide a lubrication device for a vehicle transfer case that suppresses insufficient lubrication of the oil seal between the main shaft and the transfer case when a two-wheel drive vehicle is climbing a hill.

[0009] Methods for solving problems

[0010] The key features of the present invention are: (a) a lubrication device for a vehicle transfer case, the vehicle transfer case comprising a transfer case and an oil seal, the transfer case housing: a main shaft that transmits power to a primary drive wheel; a secondary shaft that is parallel to the main shaft and disposed below the main shaft and transmits power to a secondary drive wheel; a drive belt wound around a main shaft sprocket disposed on the main shaft and a secondary shaft sprocket disposed on the secondary shaft; and an engagement clutch that disconnects the main shaft sprocket from the main shaft; the oil seal is disposed at the rearmost position of the main shaft to prevent oil leakage between the main shaft and the transfer case. The oil drawn by the oil filter is pressurized to the front end of the main shaft and lubricated through oil holes to lubricate the components of the main shaft. The oil filter is fixed in the lower oil storage space of the transfer case at a position closer to the front of the vehicle than the secondary shaft sprocket. The characteristic is that (b) during two-wheel drive by the main drive wheel of the vehicle, when climbing a slope with the oil surface of the oil filter exposed in the oil storage space, the engagement clutch is engaged to supply the oil stirred up by the rotation of the drive belt to the oil seal.

[0011] Invention Effects

[0012] According to the lubrication device of the vehicle transfer case configured as described above, during two-wheel drive of the vehicle driven by the main drive wheel, when climbing a slope where the oil level in the oil reservoir is exposed above the oil filter, the engagement clutch engages, causing the drive belt to rotate. Therefore, the oil agitated by the rotation of the drive belt is supplied to the oil seal. Thus, during two-wheel drive uphill driving, insufficient lubrication of the oil seal between the main shaft and the transfer case can be prevented. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating an example of the general structure of a vehicle to which the present invention is applied.

[0014] Figures 2(a) and (b) illustrate the oil lubrication structure inside the transfer case.

[0015] Figure 3 This is a flowchart illustrating the main parts of the control operation of the electronic control device.

[0016] Explanation of reference numerals in the attached figures

[0017] 10: Vehicle; 14: Front wheel (secondary drive wheel); 16: Rear wheel (primary drive wheel); 22: Transfer case; 40: Housing (transfer case); 44: Rear wheel side output shaft (main shaft); 46: Drive gear (main shaft sprocket); 52: Front wheel side output shaft (secondary shaft); 54: Driven gear (secondary shaft sprocket); 56: Chain (drive belt); 58: Chain break (engaging clutch); 70: Oil lubrication mechanism (lubrication device); 72: Oil seal; 74: Oil filter; 80: Electronic control device (lubrication device). Detailed Implementation

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the parts are not necessarily accurately depicted.

[0019] [Example]

[0020] Figure 1 This diagram illustrates the schematic structure of a vehicle 10 to which the present invention is applied. The vehicle 10 includes an engine 12 as a power source, front wheels 14, rear wheels 16, and a power transmission device 18 that transmits power from the engine 12 to the front wheels 14 and rear wheels 16. The rear wheels 16 are the primary drive wheels, serving as drive wheels in both two-wheel drive (2WD) and four-wheel drive (4WD) modes. The front wheels 14 are the secondary drive wheels, serving as driven wheels in 2WD and drive wheels in 4WD. The vehicle 10 is a 4WD vehicle based on a front-engine, rear-wheel drive (FR) configuration.

[0021] The power transmission system 18 includes a transmission 20 connected to the engine 12, a transfer case 22 connected to the transmission 20, a front drive shaft 24 connected to the transfer case 22, and a rear drive shaft 26. Furthermore, a front differential 28 and a front drive shaft 32 are sequentially connected starting from the front drive shaft 24, and a rear differential 30 and a rear drive shaft 34 are sequentially connected starting from the rear drive shaft 26. The transfer case 22 is a drive force distribution device that distributes the power of the engine 12 to the front wheels 14.

[0022] The front differential 28 includes a differential ring gear 28a, a differential housing 28b, a differential side gear 28c, a differential pinion 28d, a pinion shaft 28e, and an internal differential power disconnect / connection mechanism (hereinafter referred to as an internal differential disconnection mechanism) 36, etc.

[0023] The internal differential disconnect mechanism 36 is a claw clutch (i.e., an engaging clutch) that selectively connects or disconnects the power transmission path between the differential case 28b and the pinion support component 28f (i.e., between the front drive shaft 24 and the front wheel 14). The connection or disconnection of the internal differential disconnect mechanism 36 is switched by controlling the front wheel disconnect actuator 38 via the electronic control device 80 described later.

[0024] exist Figure 1 The outline of the diagram shows a cross-sectional view illustrating the general structure of the transfer case 22. The transfer case 22 includes a transfer case (hereinafter referred to as the housing) 40 that houses the constituent components. Within the housing 40, about a common axis C1, the transfer case 22 includes an input shaft 42, a rear wheel-side output shaft 44, a drive gear 46, a locking gear 48 that is non-rotatably connected to the drive gear 46, a high / low speed switching section 50 that changes the rotation of the input shaft 42 and transmits it to the rear wheel-side output shaft 44, and a chain disconnect section 58 that disconnects the drive gear 46 from the rear wheel-side output shaft 44. Furthermore, about the common axis C2, the transfer case 22 includes a front wheel-side output shaft 52, which is parallel to the rear wheel-side output shaft 44 and disposed below it within the housing 40, and a driven gear 54 integrally disposed on the front wheel-side output shaft 52. Additionally, the transfer case 22 includes 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. Furthermore, the rear wheel-side output shaft 44, the front wheel-side output shaft 52, the drive gear 46, the driven gear 54, the chain 56, and the chain break-off portion 58 correspond to the "main shaft", "secondary shaft", "main shaft sprocket", "secondary shaft sprocket", "drive belt", and "engaging clutch" in this invention, respectively.

[0025] Additionally, the transfer case 22 includes an oil lubrication mechanism 70 for oil lubrication within the transfer case 22. Furthermore, the transfer case 22 includes: an oil seal 72, which is located 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 housing 40; and an oil filter 74, which is fixed within the lower oil reservoir of the housing 40 at a position closer to the front of the vehicle than the driven gear 54, to draw in oil.

[0026] Input shaft 42 is connected to transmission 20. Rear wheel-side output shaft 44 is the main drive force transmission shaft, connected to rear drive shaft 26, transmitting power from engine 12 to rear wheels 16. Drive gear 46 is configured to rotate relative to rear wheel-side output shaft 44. Front wheel-side output shaft 52 is the secondary drive force transmission shaft, connected to front drive shaft 24, transmitting a portion of the power from engine 12 distributed by transfer case 22 to front wheels 14. Additionally, front drive shaft 24 also functions as a secondary drive force transmission shaft.

[0027] The high / low shifting unit 50 is a secondary transmission equipped with a known planetary gear unit and a meshing clutch. The cylindrical high / low shifting sleeve 50a, which is fixed relative to the rear wheel-side output shaft 44 and cannot rotate about the axis C1, switches the connection destination with the planetary gear unit by moving in the direction of the axis C1, thereby switching the high gear stage Hg (connected to the sun gear S: as shown on paper) and the low gear stage Lg (connected to the planet carrier C).

[0028] The chain disconnect section 58 switches the disconnection between the rear wheel-side output shaft 44 and the drive gear 46. The inner teeth 58b of the cylindrical chain disconnect sleeve 58a, which is fixed relative to the rear wheel-side output shaft 44 and cannot rotate around axis C1, engage with the locking gear 48 by moving towards axis C1, thereby engaging the rear wheel-side output shaft 44 and the drive gear 46. With the chain disconnect section 58 engaged, the transfer case 22 causes the rear wheel-side output shaft 44 and the drive gear 46 to rotate as a unit.

[0029] The transfer case 22 includes a TF actuator 60, which serves as a device for operating the high / low gear switching unit 50 and the chain disconnection unit 58. Through the operation of the TF actuator 60, the high / low gear switching sleeve 50a moves via the high / low operation member 62, and the chain disconnection sleeve 58a moves via the chain operation member 64. This switches the high gear stage Hg and the low gear stage Lg, and also switches the chain disconnection unit 58 between its released and engaged states.

[0030] When the chain disconnection section 58 is in the released state (as shown on paper), the power transmission path between the rear wheel side output shaft 44 and the drive gear 46 is cut off and the power is transmitted only to the rear drive shaft 26. When the chain disconnection section 58 is in the engaged state, the power is transmitted to the front drive shaft 24 and the rear drive shaft 26 respectively.

[0031] The vehicle 10 selectively switches between 2WD and 4WD modes. In 2WD mode, the power of the engine 12 is transmitted to the rear wheel 16 by releasing both the chain disconnection part 58 and the differential internal disconnection mechanism 36. In 4WD mode, the power of the engine 12 is transmitted to the rear wheel 16 and the front wheel 14 by engaging both the chain disconnection part 58 and the differential internal disconnection mechanism 36.

[0032] The vehicle 10 is equipped with an electronic control device 80, which serves as the 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 aforementioned oil lubrication mechanism 70 are equivalent to the "lubrication device" in this invention.

[0033] The electronic control unit 80 supplies various signals based on the detection values ​​of various sensors (such as G sensor 82, vehicle weight sensor 84, 4WD selection switch 86, etc.) on the vehicle 10. These signals include the vehicle's front-rear acceleration G, vehicle weight WTv, and 4WD driving selection signal 4WDDon selected by the driver. Additionally, the electronic control unit 80 outputs various command signals to various devices on the vehicle 10 (such as front wheel disconnect actuator 38, TF actuator 60, etc.). These signals include the differential disconnection operation command signal Sd for switching the state of the differential internal disconnection mechanism 36, and the TF operation command signal Sa for controlling the operation of the TF actuator 60, which switches the state of the high / low switching unit 50 and the chain disconnection unit 58.

[0034] Figure 2 is a diagram illustrating the oil lubrication structure within the transfer case 22. Figure 2(a) shows the vehicle 10 in 2WD mode on a flat road. Oil stored in the lower oil reservoir within the housing 40, up to the oil level shown in Figure 2(a), is drawn in by the oil filter 74 and pumped into the front end of the rear wheel-side output shaft 44 via an oil pump (not shown) of the oil lubrication mechanism 70, following the path shown by the thick line in the figure. The oil then lubricates the components of the rear wheel-side output shaft 44 through oil holes (not shown).

[0035] Figure 2(b) shows the state of vehicle 10 when driving in 2WD on an uphill road. When driving uphill, due to the tilt of vehicle 10, as shown in Figure 2(b), the oil level in the oil reservoir of transfer case 22 is relatively tilted. Therefore, the oil filter 74 is exposed above the oil level, the oil suction is reduced, and the oil supply from the oil pump is insufficient. As a result, there is a problem of insufficient lubrication of the components located at the rear end of the rear wheel output shaft 44. In particular, the durability may be reduced due to insufficient lubrication of the oil seal 72 located at the rearmost position of the rear wheel output shaft 44, which is provided to prevent oil leakage between the rear wheel output shaft 44 and the transfer case 40.

[0036] Therefore, during 2WD driving, in situations such as uphill driving where the oil filter 74 may become exposed above the oil level, potentially causing insufficient lubrication of the oil seal 72, the electronic control unit 80 controls the supply of oil stirred up from the oil reservoir by the rotation of the chain 56 to the oil seal 72 by engaging the chain disconnection part 58. The oil stirred up by the rotation of the chain 56, as shown by the thick arrow in the lead-out frame of Figure 2(b), is supplied to the oil seal 72 through newly provided holes h1 and h2 on the housing 40. Furthermore, although the chain disconnection part 58 is engaged, the differential internal disconnection mechanism 36 is in a disengaged state, thus maintaining 2WD driving for the vehicle 10.

[0037] Figure 3 This is a flowchart illustrating the control operation of the oil lubrication of the transfer case 22 when the electronic control unit 80 is in 2WD driving, for example, it is repeatedly executed when in 2WD driving.

[0038] exist Figure 3 First, in step S10 (hereinafter, steps omitted), it is determined whether the gradient Slo during driving exceeds a threshold θ1. For example, the gradient Slo is calculated by applying the flat road acceleration A obtained by dividing the driving torque during driving by the vehicle weight WTv and the front-to-rear acceleration G of the vehicle 10 actually detected by the G sensor 82 to a pre-set gradient calculation mapping. In addition, the threshold θ1 is pre-set by design or experiment to an appropriate value for determining whether insufficient lubrication of the oil seal 72 may occur due to the oil level of the oil filter 74 being exposed from the oil in the oil reservoir.

[0039] If the determination in S10 is affirmative, i.e., during uphill travel exceeding the threshold θ1, then in S20, it is determined whether the chain breakage section 58 is in an engaged state. If the determination in S20 is negative, then in S30, the TF actuator 60 is activated to engage the chain breakage section 58, ending the current routine. As a result, with the chain breakage section 58 engaged, oil stirred up by the rotation of the chain 56 is supplied to the oil seal 72. If the determination in S20 is affirmative, then in S40, the TF actuator 60 is stopped, ending the current routine.

[0040] If the determination in S10 is negative (i.e., the uphill travel does not exceed the threshold θ1), in S50, it is determined whether the chain breakage section 58 is in a released state. If the determination in S50 is negative, in S60, the TF actuator 60 is activated to release the chain breakage section 58, ending the routine. If the determination in S50 is positive, the process proceeds to S40, where the TF actuator 60 is stopped, ending the routine.

[0041] As described above, according to this embodiment, when the vehicle 10 is traveling in 2WD mode, during uphill driving (uphill gradient Slo > threshold θ1) when the oil level in the oil reservoir is exposed above the oil level of the oil filter 74, the chain disconnection part 58 engages, causing the chain 56 to rotate. Therefore, the oil stirred up by the rotation of the chain 56 is supplied to the oil seal 72. Thus, during uphill driving of the vehicle 10 in 2WD mode, insufficient lubrication of the oil seal 72 between the rear wheel-side output shaft 44 and the transfer case 22 can be suppressed.

[0042] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention can also be applied to other methods.

[0043] For example, in the above embodiment, the engagement clutch that disconnects the power transmission path between the front drive shaft 24 and the front wheel 14 can be replaced by an external differential power disconnection / connection mechanism or the like instead of an internal differential disconnection mechanism 36.

[0044] Furthermore, the above description is only one embodiment, and the present invention can be implemented in various ways with modifications and improvements based on the knowledge of those skilled in the art.

Claims

1. A lubrication device for a vehicle transfer case, the transfer case comprising a transfer case and an oil seal, the transfer case housing: a main shaft transmitting power to a primary drive wheel; a secondary shaft disposed parallel to the main shaft below the main shaft and transmitting power to a secondary drive wheel; a drive belt wound around a main shaft sprocket disposed on the main shaft and a secondary shaft sprocket disposed on the secondary shaft; and an engaging clutch disengaging the main shaft sprocket from the main shaft; the oil seal is disposed at the rearmost position of the main shaft to prevent oil leakage between the main shaft and the transfer case; oil drawn in by an oil filter is pressurized towards the front end of the main shaft on the vehicle side, and lubricates the components disposed on the main shaft through oil holes; the oil filter is fixed in an oil storage space in the lower part of the transfer case at a position closer to the front end of the vehicle side than the secondary shaft sprocket, characterized in that... During two-wheel drive by the main drive wheel of the vehicle, when climbing a slope where the oil level of the oil filter is exposed in the oil reservoir, the engagement clutch is engaged, supplying oil stirred up by the rotation of the drive belt to the oil seal.

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