JP2006307929A - Bearing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing structure having large capacity of a bearing and capable of saving a space, reducing friction of the bearing, and dispensing with adjustment of pre-load of the bearing. <P>SOLUTION: In this bearing structure of an intermediate helical gear 9 for transmitting driving force from an input side helical gear 5 to an output side helical gear 7, a shaft part 11 of the intermediate helical gear 9 is supported on a storage member 15 through cylindrical roller bearings 13, 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bearing structure used for a power transmission system of a vehicle.

  Patent Document 1 describes “transfer”. This transfer has an input gear, which is a triple gear train of helical gears, a pair of idler gears, and a pair of output gears. The driving force of the engine input to the input gear is the idler gears for Hi-Lo and the output gears. Is transmitted to the front and rear wheels through the gears.

The idler gear is supported on the transfer case by a tapered roller bearing.
"4.3 Toyota Land Cruiser New Car Manual" Published by Toyota Motor Corporation Service Department: January 17, 1990

  In a gear train (for example, a triple gear train) in which a plurality of gears are sequentially meshed as described above, the distance between the shafts of each gear is shortened (the input side gear and the output with respect to the intermediate gear) to make the whole compact. It is necessary to shorten each distance of the side gear: space saving). In general, a ball bearing or a tapered roller bearing is used as a bearing for the intermediate gear (the shaft portion) as in the conventional example.

  However, if a ball bearing is used, the ball diameter is large, so a sufficient effect of shortening the distance between the shafts (space saving effect) cannot be obtained, and the contact area between the ball and the inner race and outer race is small, so that the bearing is sufficient. The capacity cannot be obtained and the rigidity is insufficient.

  Further, in the case of a tapered roller bearing, preload adjustment is necessary, and therefore, friction tends to increase, which is disadvantageous for driving force transmission.

  In addition, the helical gear is subjected to a force (moment M) in the direction of tilting the shaft core due to the thrust direction component (thrust force) of the transmission drive force caused by the torsion angle of the gear. Wear or heat may occur when in contact with a member.

  Accordingly, an object of the present invention is to provide a bearing structure having a large bearing capacity, space saving, small friction, and no need for preload adjustment.

  The invention according to claim 1 is a bearing structure of an intermediate helical gear that transmits the driving force from the input side helical gear to the output side helical gear, and the shaft portion of the intermediate helical gear is accommodated in the housing member via the cylindrical roller bearing. It is characterized by being supported.

  Invention of Claim 2 is the bearing structure described in Claim 1, Comprising: Between the helical gear side axial direction end surface of the cylindrical roller which comprises the said cylindrical roller bearing, and the said axial part of the said intermediate helical gear A predetermined axial gap is provided.

  The invention according to claim 3 is the bearing structure according to claim 1 or 2, wherein the cylindrical roller is subjected to crowning.

  A fourth aspect of the present invention is the bearing structure according to any one of the first to third aspects, wherein the cylindrical roller side facing portion of the shaft portion is tapered.

  A fifth aspect of the present invention is the bearing structure according to any one of the first to fourth aspects, wherein the inner race for the cylindrical roller is arranged between the shaft portion.

  A sixth aspect of the present invention is the bearing structure according to any one of the first to fifth aspects, wherein the housing member is divided and configured by a plurality of divided components, and the intermediate helical gear is in the axial direction. The shaft portions on both sides are respectively supported by the different divided structural members via the cylindrical roller bearings.

  A seventh aspect of the present invention is the bearing structure according to any one of the first to sixth aspects, wherein the shaft portion of the intermediate helical gear is hollow.

  The invention according to claim 8 is the bearing structure according to any one of claims 1 to 7, wherein the intermediate helical gear and the shaft portion are symmetrical with respect to an axial center. Features.

  The bearing structure of claim 1 uses a cylindrical roller bearing having no inner race and a cylindrical roller (rolling element) in contact with the shaft portion as a bearing for the intermediate helical gear. It is possible to reduce the distance from each axial portion of each side helical gear and save space, and it is possible to make the bearing structure and the apparatus using the same compact.

  Further, unlike the configuration using ball bearings, the cylindrical roller bearing has a large contact area between the cylindrical roller and the mating side, so that sufficient bearing capacity and rigidity can be obtained.

  Further, unlike the configuration using a tapered roller bearing, the bearing structure of the present invention does not require adjustment of the bearing preload, and the friction can be reduced accordingly.

  In the bearing structure according to the second aspect, the predetermined axial clearance S is provided between the helical gear side axial end surface of the cylindrical roller and the shaft portion of the intermediate helical gear. When the cylindrical roller bearing receives the moment M as a radial load, contact between the intermediate helical gear and the cylindrical roller bearing and peripheral members is prevented, so that wear and heat generation are prevented.

  In the bearing structure of claim 3, since the cylindrical roller is subjected to crowning processing (processing for gradually reducing the radius of the cylindrical roller toward the end side), even when the intermediate helical gear falls as described above, the cylindrical roller The increase in surface pressure at the end of the shaft is suppressed, wear and heat generation due to high surface pressure contact with the shaft portion of the intermediate helical gear are prevented, and durability is improved.

  The bearing structure according to claim 4 has a tapered portion on the shaft portion of the intermediate helical gear that is opposed to the cylindrical roller, so that the contact between the shaft portion and the cylindrical roller, wear, and heat generation even when the intermediate helical gear is tilted. Is prevented.

  The bearing structure according to claim 5 is improved in durability if a material having a high wear resistance is used for the inner race that contacts the cylindrical roller.

  According to a sixth aspect of the present invention, there is provided a bearing structure in which one axial side of the shaft portion of the intermediate helical gear is supported by one divided component and the other axial side is supported by the other divided component. As a result, assembly becomes easier.

  In the bearing structure according to claim 7, in this configuration in which the shaft portion of the intermediate helical gear is hollow, oil circulation is promoted by the hollow holes, and the lubrication / cooling effect is improved, and the weight reduction effect of the hollow holes is obtained. It is done.

  According to the bearing structure of claim 8, in this configuration in which the intermediate helical gear and the shaft portion thereof are symmetrical with respect to the axial center, the intermediate helical gear can be assembled in the axially opposite direction. Improves.

<One Example>
The bearing structure 1 will be described with reference to FIGS. FIG. 1 shows a transfer 3 used in a rear-wheel drive four-wheel drive vehicle, and the bearing structure 1 constitutes a part of the transfer 3. Hereinafter, the left and right directions are the four-wheel drive vehicle and the left and right directions in FIG. 1, and the upper side in FIG. 1 is the front of the four-wheel drive vehicle.

[Features of bearing structure 1]
The bearing structure 1 of the present embodiment is a bearing structure of an intermediate helical gear 9 that transmits the driving force from the input side helical gear 5 to the output side helical gear 7, and the shaft portion 11 of the intermediate helical gear 9 is a cylindrical roller bearing. 13 and 13 are supported by a transfer case 15 (accommodating member).

  Further, a predetermined axial clearance S (FIGS. 2 and 7) is provided between the helical gear side axial end surface of the cylindrical roller 17 constituting each cylindrical roller bearing 13 and the shaft portion 11 of the intermediate helical gear 9. ing.

  Further, the cylindrical roller 17 is subjected to a crowning process, and a tapered portion 19 (FIG. 4) is provided at a portion of the shaft portion 11 facing the cylindrical roller 17 (made tapered).

  In addition, the transfer case 15 is divided by a casing main body 21 and case covers 23 and 25 (a plurality of divided constituent members), and the front end side shaft portion 11 of the intermediate helical gear 9 is inserted into the casing main body 21 ( The rear end side shaft portion 11 is supported by the case cover 23 (divided component member) via the cylindrical roller bearing 13.

  Further, the shaft portion 11 of the intermediate helical gear 9 is hollow, and the intermediate helical gear 9 and the shaft portion 11 are formed symmetrically with respect to the axial center line 27 (FIG. 3).

[Configuration of the above four-wheel drive vehicle]
The four-wheel drive vehicle is disposed between the engine, the transmission, the rear differential incorporated in the transmission, the transfer 3, the rear axle and the left and right rear wheels, the front differential, the propeller shaft, and the front differential. It is composed of a coupling, a front axle, left and right front wheels, and the like.

  The engine is placed horizontally at the rear of the vehicle (in front of the rear axle), and its driving force is shifted by the transmission and transmitted to the rear differential, and is distributed from the rear axle to the left and right rear wheels. If the coupling is connected, the driving force of the engine is transmitted to the front differential through the transfer 3, the propeller shaft, and the coupling, and is distributed from the front axle to the left and right front wheels. It becomes a driving state.

  Further, when the coupling is released, the front differential and the front axle and the left and right front wheels are disconnected, and the vehicle enters a two-wheel drive state of rear wheel drive.

[Configuration of Bearing Structure 1]
The cylindrical roller bearing 13 includes a cylindrical roller 17 and an outer race 29, and the outer race 29 is attached to the casing body 21 and the case cover 23, and the cylindrical roller 17 contacts the shaft portion 11 of the intermediate helical gear 9. ing.

  As shown in FIG. 1, the case covers 23 and 25 are fixed to the rear side surface and the right side surface of the casing main body 21 with bolts to form a transfer case 15.

  The output-side helical gear 7 is formed on the hollow shaft 31, the front end side of the hollow shaft 31 is supported by the casing body 21 by the ball bearing 33, and the rear end side is supported by the case cover 23 by the ball bearing 33. The hollow shaft 31 is spline-connected to a joint-side shaft member, and is connected to the propeller shaft via the joint. The rotation of the output-side helical gear 7 is transmitted to the front differential via the propeller shaft and the coupling. Communicated.

  The input-side helical gear 5 connected to the output-side helical gear 7 via the intermediate helical gear 9 is spline-connected to the shaft 35, and the front end side of the shaft 35 is supported by the casing body 21 by a tapered roller bearing 37, and the rear The end side is supported by the case cover 23 by a tapered roller bearing 39. Each tapered roller bearing 37, 39 is preloaded by a bolt 41 screwed to the rear end of the shaft 35.

  Driving force from the engine is input to the input side helical gear 5 through a differential case of the rear differential and the direction change gear set 43. The direction change gear set 43 includes a pair of bevel gears 45 and 47 meshing with each other. The bevel gear 45 is fixed to a horizontal hollow shaft 49 with bolts, and the bevel gear 47 is formed integrally with the front end of the shaft 35. The hollow shaft 49 is supported on the casing body 21 and the case cover 25 by taper roller bearings 51 and 53 on the left end side and the right end side.

  The differential case of the rear differential is splined to the hollow shaft 49 via a hollow shaft, and the right rear axle that transmits driving force from the rear differential to the right rear wheel passes through the differential case side hollow shaft and the hollow shaft 49.

  The transfer case 15 is filled with transfer oil from an oil filler 55, and includes an O-ring 57 disposed between the casing body 21 and the case cover 25, the hollow shaft 31 (output-side helical gear 7), and the casing body 21. Oil leakage from the transfer case 15 and entry of foreign matter are prevented by the seal 59 disposed between the seal 59 and the seal 61 disposed between the right rear axle and the case cover 25. Further, mixing of the transfer oil and the transmission oil is prevented by the seal 63 disposed between the casing main body 21 and the hollow shaft 49 and the X ring 65 disposed between the hollow shaft 49 and the right rear axle. .

  The driving force of the engine transmitted from the transmission to the hollow shaft 49 of the transfer 3 via the differential case of the rear differential is changed in direction by the direction changing gear set 43 and coupled to the above-described propeller shaft from the helical gears 5, 9, 7. Is transmitted to the front differential.

  As shown in FIGS. 2 and 7, the axial clearance S is formed between the stepped portion 67 (FIGS. 3, 4, 5, and 7) provided in the shaft portion 11 of the intermediate helical gear 9 and each cylindrical roller 17 of the cylindrical roller bearing 13. Further, as shown in FIGS. 3 and 4, the tapered portion 19 is formed in the stepped portion 67. When the driving force is transmitted to the intermediate helical gear 9, a force (moment M: FIG. 2) in a direction to tilt the rotation center shaft 69 (FIG. 2) due to a thrust direction component (thrust force T) of the driving force due to the torsion angle of the gear. 5), as shown in FIG. 2, the gap between the bearings (cylindrical roller bearings 13 and 13), misalignment due to accuracy errors of the transfer case 15, the shaft 11 and the cylindrical roller bearing 13, and the thermal expansion of each part of these members In addition, this fall may be promoted by rigidity (deformation) or the like.

  As shown in FIG. 2, when the contact diameter between the shaft portion 11 of the intermediate helical gear 9 and the cylindrical roller 17 of the cylindrical roller bearing 13 is r and the tilt angle of the shaft portion 11 is θ, the helical gear 9 (shaft portion 11). The axial clearance S1 on the gear end surface necessary to avoid contact between the cylindrical roller bearing 13 (cylindrical roller 17) is 2r × sin θ, and the axial clearance S is the same as the axial clearance S1, or It is slightly larger.

  Therefore, even if the intermediate helical gear 9 (shaft portion 11) falls during transmission of the driving force as shown in FIG. 5, the axial clearance S is provided, so that the intermediate helical gear 9 is moved as shown in FIG. An appropriate gap 71 remains between the cylindrical roller bearing 13 and the intermediate helical gear 9 in the tilted direction, the cylindrical roller bearing 13 receives the moment M as a radial load, and the load applied to the end surface of the cylindrical roller is reduced. Generation of wear, heat, etc. is prevented.

  Further, since the gap 71 is enlarged by forming the tapered portion 19 in the stepped portion 67 of the shaft portion 11, the function of applying the moment M to the cylindrical roller bearing 13 as a radial load, and prevention of contact, wear, heat generation, etc. Function is further improved.

  In addition, as shown in FIG. 8, the end of each cylindrical roller bearing 13 is crowned so that the end of the cylindrical roller 17 can be supported even if the intermediate helical gear 9 and the shaft 11 are tilted as shown in FIG. In this case, strong contact with the shaft 11 is prevented.

  The graphs 73 and 75 in FIG. 9 and FIG. 10 show such an effect by the crowning. The graph 73 in FIG. 9 shows the surface pressure distribution when the cylindrical roller 17 is crowned, and the graph in FIG. 75 shows the surface pressure distribution when no crowning is applied. In each graph, the horizontal axis represents the distance from the center of the cylindrical roller in the axial direction, and the vertical axis represents the surface pressure generated in the cylindrical roller. In the graph 75 of FIG. 10, a large peak 77 occurs in the surface pressure at the end portion of the cylindrical roller that is not crowned, and wear, heat generation, etc. between the cylindrical roller and the shaft portion are increased accordingly. However, in the graph 73 of FIG. 9 subjected to crowning, the surface pressure is dispersed in a wide range as indicated by the arrow 79 at the portion where the large peak 77 is generated in the graph 75. The wear, heat generation, etc. between 11 are greatly reduced, the operation is kept normal, and the durability is improved accordingly.

[Effect of bearing structure 1]
The bearing structure 1 does not have an inner race, and cylindrical roller bearings 13 and 13 in which the cylindrical roller 17 is in direct contact with the shaft portion 11 are used as the bearing of the intermediate helical gear 9. It becomes possible to save space by shortening the distance between the shaft 35 (shaft portion) of the input side helical gear 5 and the hollow shaft 31 (shaft portion) of the output side helical gear 7. Therefore, the transfer 3 can be made compact.

  Further, unlike the configuration using ball bearings, the cylindrical roller bearing 13 has a large contact area between the cylindrical roller 17 and the shaft portion 11, so that sufficient bearing capacity and rigidity can be obtained.

  Further, unlike the configuration using the tapered roller bearing, it is not necessary to adjust the preload of the bearing, and the friction can be reduced accordingly.

  In addition, since a predetermined axial clearance S is provided between the end face of the cylindrical roller 17 and the shaft portion 11 (stepped portion 67) of the intermediate helical gear 9, even if the intermediate helical gear 9 falls due to the moment M, the moment Since the cylindrical roller bearing 13 receives M as a radial load, the contact between the intermediate helical gear 9 and the cylindrical roller bearing 13 is prevented, so that wear and heat generation due to the contact between both are prevented.

  Further, since the cylindrical roller 17 is crowned, an increase in the surface pressure at the end of the cylindrical roller 17 is suppressed when the intermediate helical gear 9 is tilted. This prevents wear and heat generation due to high surface pressure and improves durability.

  Further, by providing the tapered portion 19 on the shaft portion 11 (stepped portion 67) of the intermediate helical gear 9, a function of applying the moment M to the cylindrical roller bearing 13 as a radial load when the intermediate helical gear 9 falls down; The function of preventing contact, wear, heat generation, etc. is further improved.

  Further, since the front side of the shaft portion 11 of the intermediate helical gear 9 is supported by the casing body 21 of the transfer case 15 and the rear side is supported by the case cover 23, the intermediate helical gear 9 can be easily assembled.

  Further, since the shaft portion 11 of the intermediate helical gear 9 is made hollow, the circulation of oil is promoted, the lubrication / cooling effect is improved, and the lightening effect is obtained by the amount corresponding to the hollow hole.

  Further, since the intermediate helical gear 9 and the shaft portion 11 thereof are symmetrical with respect to the center line 27, the intermediate helical gear 9 can be assembled in the opposite direction in the axial direction, and the assemblability is improved accordingly. .

[Other Embodiments Included within the Scope of the Present Invention]
The bearing structure of the present invention may be used for a gear train of three or more gear trains. In this case, since the input side helical gear and the output side helical gear are intermediate helical gears, all of them are subjected to moment. What is necessary is just to comprise so that it may support using a cylindrical roller bearing.

  In addition, the input side helical gear and the output side helical gear may be supported by cylindrical roller bearings, and in this way, the effect of shortening the distance between the shafts, the effect of increasing the bearing capacity and rigidity, and the adjustment of the preload are similarly eliminated. The effect and the effect of reducing friction can be obtained.

It is sectional drawing which shows the transfer 3 using the bearing structure 1 of one Example. It is sectional drawing which shows the intermediate | middle helical gear 9 in the fall state, and shows axial direction clearance S1 required in order to prevent a contact with the cylindrical roller 17 at that time. 3 is a cross-sectional view of an intermediate helical gear 9. FIG. FIG. 4 is a detailed view of a portion R in FIG. 3. It is sectional drawing which shows the cylindrical roller bearings 13 and 13 and the intermediate helical gear 9 in the fallen state. FIG. 6 is a detailed view of a portion X in FIG. 5. FIG. 6 is a detailed view of a Y part in FIG. 5. FIG. 6 is a detailed view of a Z part in FIG. 5. It is a graph which shows the surface pressure distribution of the cylindrical roller which gave crowning. It is a graph which shows the surface pressure distribution of the cylindrical roller which does not give crowning.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bearing structure 5 Input side helical gear 7 Output side helical gear 9 Intermediate helical gear 11 Shaft part 13 of intermediate helical gear 9 Cylindrical roller bearing 15 Transfer case (accommodating member)
17 Cylindrical roller 19 Tapered part 21 Casing body (divided component)
23 Case cover (split component)
27 Axial centerline of shaft 11

Claims (8)

A bearing structure of an intermediate helical gear that transmits driving force from the input side helical gear to the output side helical gear,
A bearing structure characterized in that the shaft portion of the intermediate helical gear is supported by a housing member via a cylindrical roller bearing. The bearing structure according to claim 1,
A bearing structure characterized in that a predetermined axial clearance is provided between a helical gear side axial end surface of a cylindrical roller constituting the cylindrical roller bearing and the shaft portion of the intermediate helical gear. The bearing structure according to claim 1 or 2,
A bearing structure, wherein the cylindrical roller is crowned. The bearing structure according to any one of claims 1 to 3,
A bearing structure, wherein the cylindrical roller side facing portion of the shaft portion is tapered. The bearing structure according to any one of claims 1 to 4,
A bearing structure in which the inner race for a cylindrical roller is disposed between the shaft portion. The bearing structure according to any one of claims 1 to 5,
The accommodating member is divided and configured by a plurality of divided components, and the intermediate helical gear is supported by the different divided components via the cylindrical roller bearings at the shaft portions on both sides in the axial direction. Characteristic bearing structure. The bearing structure according to any one of claims 1 to 6,
The bearing structure, wherein the shaft portion of the intermediate helical gear is hollow. A bearing structure according to any one of claims 1 to 7,
The bearing structure, wherein the intermediate helical gear and the shaft portion are symmetrical with respect to an axial center.

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