JP2005249189A - Bearing device for transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a transmission, improved in its efficiency by reducing rotating torque of a rolling bearing. <P>SOLUTION: An axial load receiving-side bearing 7 of the pair of rolling bearings 7, 8 is composed of the combination of a thrust bearing 11 receiving only the axial load and a radial bearing 12 receiving only radial load. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a transmission bearing device, and more particularly to a transmission bearing device used in a transmission for automobiles and various industrial machines.

  Conventionally, in a transmission such as an automobile, various types of bearing devices for supporting a gear shaft on a transmission casing have been proposed (for example, see Non-Patent Document 1 and Patent Documents 1 and 2).

  As shown in FIG. 9, in the manual transmission of an FF vehicle disclosed in Non-Patent Document 1, an input shaft 201 that is a gear shaft, an intermediate shaft 202, an output shaft 203, each shaft 201, A plurality of gears (gears) 204a to 208a and 204b to 207b provided in 202 and 203 are incorporated. The input shaft 201 is supported by a deep groove ball bearing 209 and a cylindrical roller bearing 210, the intermediate shaft 202 is supported by a pair of deep groove ball bearings 211 and 212, and the output shaft 203 is supported by a pair of tapered roller bearings 213 and 214, respectively.

  Further, in the automobile transmission of Patent Document 1 shown in FIG. 10, the input shaft 226, the intermediate shaft 227, and the output shaft 228, which are gear shafts provided with a plurality of gears 221a to 225a and 221b to 225b, are sealed plates. Are supported by attached deep groove ball bearings 229 to 232.

  Furthermore, in the automobile transmission of Patent Document 2 shown in FIG. 11A, a counter shaft 242 that is a gear shaft provided with an idle gear 240 and a pinion reduction gear 241 is provided with a cylindrical roller bearing 243 and FIG. It is supported by the compound rolling bearing 244 shown in (b).

In an automobile transmission as shown in FIGS. 9 to 11, a helical gear is generally adopted as a type of these gears. When helical gears are engaged, both radial load and axial load act on the bearing via the gear shaft. Therefore, at least one of the pair of bearings that support the gear shaft includes a tapered roller bearing and a collar. A rolling bearing capable of applying both a radial load and an axial load (synthetic load) such as a cylindrical roller bearing with a groove, a deep groove ball bearing, and a composite rolling bearing in FIG. 11B is used. For example, in the input shaft 201 of FIG. 9, the cylindrical roller bearing 210 cannot apply an axial load, and thus a deep groove ball bearing 209 is used to apply the axial load. Further, the compound rolling bearing 244 of FIG. 11 (b) is configured by integrating a ball bearing 245 and a cylindrical roller bearing 246, and only the axial load is shared between the inner ring 247 and the outer ring 248. A ball row 249 with the clearance adjusted and a cylindrical roller row 250 with the bearing internal clearance adjusted to share only the radial load are interposed. These bearing types are arbitrarily selected according to usage conditions and the like.
Takuya Hashida, “Driving Train for Illustrated Cars”, Sankaido, 1994, p. 31 US Pat. No. 4,309,916 (FIG. 1) Utility Model No. 2524492 (Fig. 3)

  By the way, the transmission for automobiles as shown in FIGS. 9 to 11 changes the combination of gears to increase / decrease the rotation speed of the output shaft with respect to the rotation of the input shaft transmitted from the engine. As the rotational speed of the shaft changes, the gears engaged by the shift work for switching the gears of the transmission change. When the rotation speed and the meshing gear change, the load applied to the bearing naturally changes. Therefore, the load range applied to the bearing used in the transmission for an automobile is very wide.

  In selecting a bearing for use in an automotive transmission with a very wide load range, it is necessary to increase the bearing size to ensure functions such as bearing life and static strength even under heavy load conditions. was there. For this reason, there has been a problem that the rotational torque of the bearing is increased and the efficiency of the transmission is lowered.

  In particular, in a bearing to which a composite load is applied, the radial load may be very large with respect to the axial load, or the axial load may be very large with respect to the radial load. For this reason, bearings that are subject to composite loads must have a wide life span for radial and axial loads, and are larger than bearings that only receive radial or axial loads. There is a problem in that the rotational torque increases with the increase of.

  That is, as shown in FIGS. 12A to 12C, the number of rolling elements that receive a load increases in the case of a bearing that receives a combined load compared to the case of a bearing that only loads a radial load. Rotating torque increases because the load range is widened.

  Further, when considering by bearing type, in the case of a tapered roller bearing, there is a problem that the sliding friction of the head surface at the large collar portion of the inner ring increases and the rotational torque of the bearing increases. Further, in the case of a cylindrical roller bearing with a flange, there is a problem that the sliding friction of the end surface increases at the flange portion, and the rotational torque of the bearing increases. Further, in the case of a deep groove ball bearing, when an axial load is applied in addition to a radial load, a contact angle is generated in each ball, sliding friction such as spin increases, and there is a problem that a rotational torque increases accordingly. For this reason, regardless of the bearing type, there has been a problem that the rotational torque of the rolling bearing that applies the combined load is large and the efficiency of the transmission is reduced.

  Further, the compound rolling bearing shown in FIG. 11B is supported by the compound rolling bearing 244 because the ball train 249 and the cylindrical roller train 250 are arranged in parallel between the inner ring 247 and the outer ring 248. The length of the gear shaft 242 becomes longer. Along with this, the casing must be enlarged, and there is a problem that the gear shaft and the casing are increased in size and weight. Further, since the ball row 249 and the cylindrical roller row 250 are arranged between the inner ring 247 and the outer ring 248, each PCD (pitch circle diameter) can hardly be changed, and the PCD of each row is used as a use condition. However, there was also a problem that it could not be set appropriately.

  The present invention has been made in view of the above-described problems, and the object thereof is to ensure a bearing life in a wide load range without increasing the bearing size, and further increase the size of the gear shaft and the casing. An object of the present invention is to provide an efficient transmission bearing device that reduces the rotational torque of a rolling bearing without causing an increase in weight.

The above object of the present invention can be achieved by the following constitution.
(1) A transmission provided with a pair of rolling bearings interposed between a casing and a transmission gear shaft disposed in the casing and supporting the gear shaft so as to be relatively rotatable with respect to the casing. Machine bearing device,
At least one of the pair of rolling bearings comprises a combination of a thrust bearing that receives only an axial load and a radial bearing that receives only a radial load.
(2) The transmission bearing device according to (1), wherein an outer ring of the radial bearing is attached to the casing by a clearance fit.
(3) At least one of the pair of bearing rings of the thrust bearing and at least one of the pair of bearing rings of the radial bearing are shared,
The transmission bearing device according to (1), wherein the rolling element row of the thrust bearing and the rolling element row of the radial bearing have different PCDs.
(4) At least one of the pair of bearing rings of the thrust bearing and at least one of the pair of bearing rings of the radial bearing are shared,
The bearing device for a transmission according to (1), wherein at least one of the pair of bearing rings of the thrust bearing is made of a steel plate in which a raceway groove is drawn.

  According to the transmission bearing device of the present invention, since at least one of the pair of rolling bearings is a combination of a thrust bearing that receives only an axial load and a radial bearing that receives only a radial load, it is wide without increasing the bearing size. The bearing life can be ensured in the load range, and the gear shaft and casing are not increased in size and weight. Further, the rotational torque of the rolling bearing can be reduced, and an efficient transmission bearing device can be obtained.

In addition, since at least one of the pair of bearing rings of the thrust bearing and at least one of the pair of bearing rings of the radial bearing are shared, the bearing width can be kept small, the gear shaft and the casing are enlarged, and the weight The increase can be further suppressed.
Furthermore, since the PCD of each row can be arbitrarily adjusted according to the use conditions, it is possible to obtain an appropriate bearing size that matches the use conditions.
Further, since the raceway of the ball train that shares only the axial load is made of a steel plate in which the raceway groove is drawn, the production is easy and the production cost can be reduced.

  Hereinafter, the bearing device for transmissions concerning each embodiment of the present invention is explained in detail with reference to drawings. The present invention is characterized by the configuration of a rolling bearing used in a transmission, and the other configurations of the bearing device can be those of a known transmission bearing device as shown in FIGS. Therefore, FIGS. 1-4 which show the bearing apparatus for transmissions of each embodiment have shown only the schematic structure required in order to demonstrate the characteristic of this invention.

(First embodiment)
First, a transmission bearing device according to a first embodiment will be described with reference to FIG. In the bearing device 1 shown in FIG. 1, a first transmission gear shaft 4 provided with a first gear 3 in a casing 2, and a second gear 5 that can mesh with the first gear 3. Is provided with a second transmission gear shaft 6. Each of the first and second gears 3 and 5 is a helical gear. A first pair of rolling bearings 7 and 8 are interposed between the casing 2 and the first gear shaft 4, and the first pair of rolling bearings 7 and 8 are interposed between the casing 2 and the second gear shaft 6. Two pairs of rolling bearings 9 and 10 are interposed. Thus, the first and second gear shafts 4 and 6 are supported so as to be rotatable relative to the casing 2.

  In the first pair of rolling bearings 7 and 8, one rolling bearing 7 is the combined load load side, the thrust ball bearing 11 which is a thrust bearing of the present invention that receives only an axial load, and the present invention that receives only a radial load. It is configured by a combination with a deep groove ball bearing 12 which is a radial bearing. The other rolling bearing 8 is a cylindrical roller bearing and supports a radial load. The thrust ball bearing 11 and the deep groove ball bearing 12 are disposed adjacent to each other in the axial direction of the gear shaft 4, and the deep groove ball bearing 12 is positioned closer to the first gear 3 with respect to the thrust ball bearing 11. .

  In the case of the second pair of rolling bearings 9 and 10, one rolling bearing 10 is a combination of a thrust ball bearing 13 that receives only an axial load and a deep groove ball bearing 14 that receives only a radial load, and the other rolling bearing. The bearing 9 is constituted by a deep groove ball bearing. The thrust ball bearing 13 and the deep groove ball bearing 14 are also arranged adjacent to each other in the axial direction of the gear shaft 6, and the deep groove ball bearing 14 is positioned closer to the second gear 5 with respect to the thrust ball bearing 13. .

  Further, in the deep groove ball bearings 12 and 14 that receive a radial load, which is a bearing on the composite load load side, the outer diameter surfaces of these outer rings 12a and 14a and the inner diameter surface of the casing 2 are clearance fit, and the outer rings 12a and 14a is attached to the casing 2 so as to be freely movable in the axial direction. For this reason, the deep groove ball bearings 12 and 14 can receive only the radial load without applying the axial load generated from the gears 3 and 5.

  In the bearing device 1 configured as described above, a thrust force is generated when the first and second gears 3 and 5 mesh with each other to transmit power. Thereby, an axial load and a radial load act on the first and second rolling bearings 7 to 10 via the first and second gear shafts 4 and 6. At this time, in the axial load side bearings of the first and second rolling bearings 7 to 10, the thrust ball bearings 11 and 13 receive only the axial load, and the deep groove ball bearings 12 and 14 receive only the radial load. Since the load applied to each bearing can be reduced and the bearing size does not need to be increased, the rotational torque acting on the bearing can be reduced.

  Therefore, according to the present embodiment, since the composite load side bearing is a combination of the thrust ball bearing 11 that receives only the axial load and the radial ball bearing 12 that receives only the radial load, the load applied to each bearing is reduced. The bearing life can be ensured without increasing the bearing size. Further, the rotational torque can be reduced in the bearing on the combined load load side, and an efficient transmission can be obtained.

  The bearing on the combined load side is a combination of deep groove ball bearings 12 and 14 and thrust ball bearings 11 and 13, but any combination of a thrust bearing that receives only an axial load and a radial bearing that receives only a radial load. The type of each bearing is not limited. In particular, when the radial load is large, a cylindrical roller bearing may be applied instead of the deep groove ball bearings 12 and 14. Similarly, when the axial load is large, thrust needle roller bearings may be applied instead of the thrust ball bearings 11 and 13.

  Further, the first and second gear shafts 4 and 6 of the present embodiment may represent an input shaft and an intermediate shaft in the transmission bearing device shown in FIG. 9 or FIG. 10, for example. The input shaft and the output shaft, the intermediate shaft and the output shaft may be shown, or the countershaft shown in FIG. 11 may be used. The first and second gears 3 and 5 may also be any of known gears provided on the input shaft, the intermediate shaft, the output shaft, the counter shaft, and the like.

(Second Embodiment)
Next, a transmission bearing device according to a second embodiment of the present invention will be described. In the transmission bearing device 21 shown in FIG. 2, a first transmission gear shaft 24 in which a first gear 23a and a third gear 23b are provided in a casing 22, and a first gear 23a. And a second speed change gear shaft 26 provided with a second gear 25a that can mesh with the third gear 23b and a fourth gear 25b that can mesh with the third gear 23b. Each of the gears 23a, 23b, 25a, and 25b is a helical gear. A first pair of rolling bearings 27 and 28 are interposed between the casing 22 and the first gear shaft 24, and the first pair of rolling bearings 27 and 28 are interposed between the casing 22 and the second gear shaft 26. Two pairs of rolling bearings 29 and 30 are interposed. Thus, the first and second gear shafts 24 and 26 are supported so as to be rotatable relative to the casing 22.

  In the first pair of rolling bearings 27 and 28, one rolling bearing 28 is on the combined load load side, and in the second pair of rolling bearings 29 and 30, one rolling bearing 29 is on the combined load load side. These rolling bearings 28 and 29 on the combined load side are a combination of a thrust bearing that receives only an axial load and a radial bearing that receives only a radial load. Here, as a representative example, the rolling bearing 29 will be described with reference to FIG.

  The rolling bearing 29 is composed of a combination of a thrust ball bearing 31 that receives only an axial load and a radial ball bearing 32 that receives only a radial load. The thrust ball bearing 31 and the radial ball bearing 32 are mutually connected by a single rotating member 34. The inner ring is shared. The thrust ball bearing 31 includes an inner ring constituted by a pair of race rings, an outer ring 33 and a rotating member 34, an arc-shaped raceway groove 33a formed on an axial end face of the outer ring 33, and an axial end face of the rotating member 34. Are provided with balls 36 which are rolling elements arranged at equal intervals in the circumferential direction via a retainer 35. Further, the radial ball bearing 32 includes an inner ring constituted by a pair of race rings, an outer ring 37 and a rotating member 34, and a raceway groove 37 a having an arc cross section formed on the inner circumferential surface of the outer ring 37 and the outer circumference of the rotating member 34. Balls 39, which are rolling elements, are arranged at regular intervals in the circumferential direction via cages 38 between the raceway grooves 34b having a circular arc cross section formed on the surface.

  Further, the raceway groove 34 a of the thrust ball bearing 31 is formed on the end surface in the axial direction of the rotating member 34, and the raceway groove 34 b of the radial ball bearing 32 is formed on the outer peripheral surface of the rotating member 34. The rolling element rows of 36 and the rolling element rows of the balls 39 of the radial ball bearing 32 have different PCDs. In this case, since the PCD of the rolling element row of the radial ball bearing 32 is set larger than that of the rolling element row of the thrust ball bearing 31, the number of balls 39 can be increased, and the radial load capacity is increased. Can do.

  Therefore, according to the present embodiment, since the composite load side bearing is a combination of the thrust ball bearing 31 that receives only the axial load and the radial ball bearing 32 that receives only the radial load, the load applied to each bearing is reduced. The bearing life and static strength can be ensured without increasing the bearing size. Furthermore, because the PCD and rolling element type of each row can be arbitrarily changed depending on the use conditions, the bearing torque can be made appropriate for the use conditions, so the rotational torque of the bearing can be kept small, The efficiency of the transmission to which the rolling bearings 28 and 29 are applied can be improved.

  Further, since the inner ring of the thrust ball bearing 31 and the inner ring of the radial ball bearing 32 are shared, the axial length can be shortened, and the gear shaft and the casing are not increased in size and weight.

  In addition, the rolling bearings 28 and 29 can change PCD of each row | line | column and a rolling element form according to use conditions. FIGS. 3B to 3D show rolling bearings 50, 60, 70 which are first to third modifications applicable to the rolling bearings 28, 29.

  The rolling bearing 50 includes a combination of a thrust ball bearing 51 that receives only an axial load and a radial ball bearing 52 that receives only a radial load. The thrust ball bearing 51 and the radial ball bearing 52 are mutually connected by a single stationary member 53. The outer ring is shared, and the inner ring is shared by a single rotating member 54. The thrust ball bearing 51 includes an outer ring constituted by a stationary member 53 as a pair of races and an inner race constituted by a rotating member 34, and a raceway groove 53a having an arcuate cross section formed on an axial end surface of the stationary member 53. Balls 56 that are rolling elements arranged at equal intervals in the circumferential direction via a cage 55 are provided between a raceway groove 54 a having an arcuate cross section formed on the axial end surface of the rotating member 54. Further, the radial ball bearing 52 includes a raceway having a circular arc cross section formed on an inner ring constituted by an outer ring and a rotation member 54 constituted by a stationary member 53 as a pair of raceways and a rotary member 54. Balls 58 which are rolling elements arranged at equal intervals in the circumferential direction via a cage 57 are provided between 53b and a raceway groove 54b having an arc-shaped cross section formed on the outer peripheral surface of the rotating member 54.

  With the above configuration, the rolling element row of the balls 56 of the thrust ball bearing 51 and the rolling element row of the balls 58 of the radial ball bearing 52 have different PCDs, and the PCD of the rolling element row of the thrust ball bearing 51 is a radial ball bearing. Since it is set larger than that of the 52 rolling element rows, the number of balls 56 can be increased, and the axial load capacity can be increased.

  Further, since the outer and inner rings of the thrust ball bearing 51 and the radial ball bearing 52 are shared, the axial length can be shortened, and the gear shaft and casing are not increased in size and weight.

  Further, the rolling bearing 60 shown in FIG. 3C is replaced with the radial cylindrical roller bearing 61 instead of the radial ball bearing 32 shown in FIG. 3A, and the rolling bearing 70 shown in FIG. Instead of the thrust ball bearing 51, a thrust cylindrical roller bearing 71 is used.

  The radial cylindrical roller bearing 61 in FIG. 3C includes an inner ring constituted by an outer ring 37 ′ and a rotating member 34 ′, and an inner circumferential surface 37c of the outer ring 37 ′ and an outer circumferential surface 34c of the rotating member 34 ′. Cylindrical rollers 64 which are rolling elements arranged at equal intervals in the circumferential direction via a cage 63.

  Further, the thrust cylindrical roller bearing 71 of FIG. 3 (d) includes an outer ring constituted by a stationary member 53 ′ that is a pair of race rings, an inner ring constituted by a rotating member 54 ′, and an axial end surface of the stationary member 53 ′. Cylindrical rollers 73 which are rolling elements arranged at equal intervals in the circumferential direction via a cage 72 are provided between 53c and the axial end face 54c of the rotating member 54 ′.

Thus, in the present invention, a cylindrical roller bearing may be applied as a thrust bearing or a radial bearing according to use conditions, or a cylindrical roller bearing may be applied to both bearings.
Note that the outer diameter surfaces of the outer rings 37, 53, 37 ′ and 53 ′ of the radial bearing shown in FIGS. 3A to 3D are preferably clearance fit with the inner diameter surface of the casing 22.

(Third embodiment)
Next, a transmission bearing device according to a third embodiment of the present invention will be described with reference to FIGS. The transmission bearing device of the present embodiment is different from that of the second embodiment in the configuration of the rolling bearing on the composite load load side in FIG. 2, and therefore other equivalent parts are denoted by the same reference numerals. The description will be omitted or simplified.

  FIG. 4A shows a rolling bearing 80 applied to the rolling bearings 28 and 29 on the combined load side of the transmission bearing device of FIG. In the rolling bearing 80, a thrust ball bearing 81 that receives only an axial load has a steel plate outer ring 82 in a notch portion 22 a of the casing 22. In the outer ring 82, a raceway groove 82a having a circular arc cross section corresponding to the rolling element row of the balls 36 is formed by drawing. The other configuration is the same as that of the rolling bearing 29 in FIG. 3A, and the thrust ball bearing 81 and the radial ball bearing 32 are configured by sharing a single inner ring with a single rotating member 34, and The rolling element row of the thrust ball bearing 81 and the rolling element row of the radial ball bearing 32 have different PCDs.

Therefore, according to the transmission bearing device of the present embodiment, the outer ring 82 of the thrust ball bearing 81 is made of a steel plate in which the raceway groove 82a is drawn, so that it is easy to manufacture and the cost can be reduced. it can.
The steel plate material is generally carbon steel, but may be carburized or carbonitrided carbon steel, or hardened and tempered carbon tool steel, and further carburized or carbonitrided for machine structures. Alloy steel (for example, SCM415) may be used.

  Furthermore, as a modification of the combined load load side rolling bearing according to the present embodiment, rolling bearings 90 to 110 as shown in FIGS.

  In the thrust ball bearing 91 of the rolling bearing 90 shown in FIG. 4B, the flanges 92a and 92b are fitted to the notch portion 22b of the U-shaped casing 22 instead of the outer ring 82 in FIG. An outer ring 92 made of a steel plate provided with is applied. The outer ring 92 is also formed with a drawing groove 92c having a circular arc cross section corresponding to the rolling element row of the balls 36.

Also, the rolling bearings 100 and 110 shown in FIGS. 4 (c) and 4 (d) are the same as the thrust ball bearings 81 and 91 shown in FIGS. 4 (a) and 4 (b), and FIG. 3 (c). In the present embodiment, the present invention can be variously changed in terms of the type of rolling bearing and the number of rolling elements according to the use conditions.
The outer diameter surfaces of the outer rings 37 and 37 ′ of the radial bearing shown in FIGS. 4A to 4D are also preferably fitted with the inner diameter surface of the casing 22.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.

  Hereinafter, in order to confirm the effect of the present invention, the following experiment was performed using the transmission bearing device of the first embodiment. First, Table 1 shows the test bearings used in this experiment, and Table 2 shows the combinations of test bearings on which the experiments were conducted. In addition, the deep groove ball bearing and the thrust ball bearing used in the experiment used SUJ2, which is a high carbon chrome bearing steel, for all members of the outer ring, the inner ring, and the ball. However, these members can be made of chromium steel, such as SCr420, SCr430, SCr440, medium carbon chromium molybdenum steel, and medium carbon nickel chromium molybdenum steel. Moreover, the material of each structural member does not necessarily need to be the same, and it can also be used combining a dissimilar material for each member.

  With respect to the two types of combinations I and II shown in Table 2, the bearing torque was measured using a test apparatus 120 as shown in FIGS. The shaft 121 on which the inner ring of the test bearing is fitted and fixed is taper-fitted to the upper end portion of the drive shaft 122 and is driven to rotate by the drive shaft 122. The outer ring of the test bearing is fitted and fixed inside the housing 124 via the outer ring holders 123 and 123 '. A predetermined lubricating oil can be supplied into the housing 124 through an oil supply hole 125. Further, a predetermined axial load can be freely applied to the upper surface of the housing 124 via a static pressure pad 126. Further, a predetermined radial load can be applied to the outer peripheral surface of the housing 124 via a static pressure pad 127. Further, a load cell 129 is provided between the distal end portion of the arm piece 128 fixed to the outer peripheral surface of the housing 124 and a fixed portion (not shown) so that the bearing torque applied to the housing 124 when the shaft 121 rotates can be measured.

  In the case of the combination II, as shown in FIG. 6, the outer ring holder 123 ′ and the outer ring outer diameter of the deep groove ball bearing are arranged so that the radial load can be surely shared by the deep groove ball bearing and the axial load can be surely shared by the thrust ball bearing. The fit is a clearance fit, and sufficient clearances are provided in the a and b portions.

  FIG. 7 shows the experimental results for determining the relationship between the rotational speed and the bearing torque for each of combination I (deep groove ball bearing only) and combination II (deep groove ball bearing + thrust ball bearing) shown in Table 2. The experiment was performed by supplying lubricating oil (equivalent to ISO VG32) at an oil temperature of 40 ° C. at a rate of 300 ml / min and applying each load condition shown in Table 3 to the test bearing. FIG. 7A shows the load condition (1), FIG. 7B shows the load condition (2), and FIG. 7C shows the experimental result for the load condition (3).

  From FIG. 7, it can be seen that the combination of the deep groove ball bearing that shares only the radial load and the thrust ball bearing that shares only the axial load is smaller than the bearing torque of the deep groove ball bearing that loads the combined load.

  FIG. 8 shows the result of calculating the fatigue life of the bearing under the load condition (3) shown in Table 3 by calculation. The vertical axis shows the ratio of the fatigue life of combination II when the fatigue life of combination I is 1. As shown in FIG. 8, the fatigue life of a combination of a deep groove ball bearing that shares only a radial load and a thrust ball bearing that shares only an axial load is about five times the fatigue life of a deep groove ball bearing that receives a composite load. I understand that

It is a mimetic diagram of the bearing device for transmissions in a 1st embodiment of the present invention. It is a schematic diagram of the bearing apparatus for transmissions in 2nd and 3rd embodiment of this invention. It is the II section enlarged view of FIG. 2, (a) is a rolling bearing of 2nd Embodiment, (b) is a rolling bearing of the 1st modification of 2nd Embodiment, (c) is 2nd Embodiment. (D) has shown the rolling bearing of the 3rd modification of 2nd Embodiment. It is the II section enlarged view of Drawing 2, (a) is a rolling bearing of a 3rd embodiment, (b) is a rolling bearing of the 1st modification of a 3rd embodiment, (c) is a 3rd embodiment. (D) has shown the rolling bearing of the 3rd modification of 3rd Embodiment. It is sectional drawing which shows the test apparatus in the Example of this invention. It is sectional drawing which shows the test apparatus in the Example of this invention. It is a graph which shows the relationship between the rotational speed and bearing torque in the Example of this invention. It is a graph which shows the fatigue life comparison in the Example of this invention. It is a figure which shows the conventional bearing apparatus for transmissions. It is a figure which shows the other conventional bearing apparatus for transmissions. It is a figure which shows the conventional further another bearing apparatus for transmissions. It is a figure which shows the change of the load zone by an axial load.

Explanation of symbols

1,21 Bearing device for transmission 2,22 Casing 3,23a First gear
4,24 First transmission gear shaft 5,25a Second gear 6,26 Second transmission gear shaft 23b Third gear
25b 4th gear
7, 10, 28, 29 Rolling bearing (composite load bearing)
8, 9, 27, 30 Rolling bearing 11, 13, 31, 51, 81, 91 Thrust ball bearing (thrust bearing)
12, 14, 32, 52 Deep groove ball bearings (radial bearings)
61, 71 Thrust cylindrical roller bearing (thrust bearing)

Claims (4)

A transmission bearing device including a pair of rolling bearings interposed between a casing and a transmission gear shaft disposed in the casing and supporting the gear shaft so as to be relatively rotatable with respect to the casing. There,
At least one of the pair of rolling bearings comprises a combination of a thrust bearing that receives only an axial load and a radial bearing that receives only a radial load.   2. The transmission bearing device according to claim 1, wherein the outer ring of the radial bearing is attached to the casing by a clearance fit. At least one of the pair of raceways of the thrust bearing and at least one of the pair of raceways of the radial bearing are shared,
2. The transmission bearing device according to claim 1, wherein the rolling element row of the thrust bearing and the rolling element row of the radial bearing have different PCDs. At least one of the pair of raceways of the thrust bearing and at least one of the pair of raceways of the radial bearing are shared,
The bearing device for a transmission according to claim 1, wherein at least one of the pair of bearing rings of the thrust bearing is made of a steel plate in which a raceway groove is drawn.

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