JPH0620900Y2 - Roller bearings for vehicle transmissions - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to roller bearings used in vehicle transmissions and transaxles, and more specifically, automotive transmissions that are effective in achieving low torque, seizure resistance, and high rigidity. Roller bearings.

[Conventional technology]

FIG. 1 shows an example of an automobile transmission. An input shaft 2, a drive pinion 3 and an output shaft 4 are arranged in series in a case 1, and a counter shaft 5 and a reverse shaft 6 are arranged in parallel with the output shaft 4. The drive pinion 3 and the shafts 2, 4 and 5 are provided with gears 7 and the rotation of the input shaft 2 is output by changing the meshing of the gears by an operation from the outside of the case 1. It is designed so that it can be taken out by shifting or reversing to the to shaft 4.

Each of the shafts 2, 4, 5, 6 and the drive pinion 3
It is necessary to supply lubricating oil to the bearing that rotatably supports, but the lower half of the case 1 is filled with lubricating oil, and the bearings of the counter shaft 5 and the reverse shaft 6 are immersed in the lubricating oil. Therefore, there is no particular lubrication problem.

On the other hand, the bearings that support the input shaft 2, the drive pinion 3, and the output shaft 4 are higher than the oil level of the lubricating oil, so that it is necessary to supply the lubricating oil. Therefore, the lubricating oil by the rotation of the gear group is required. Lubrication is carried out by using the splashes of.

FIG. 2 shows the details of the bearing structure of the input shaft 2, the drive pinion 3, and the output shaft 4. The input shaft 2 and the drive pinion 3 are supported by the cylindrical roller bearings 8, 8 and the end portion of the drive pinion 3 is supported. Is supported by the input shaft 2 via the pilot needle bearing 9, and further the output shaft 4
Is also supported by the drive pinion 3 via the pilot needle bearing 10.

The input shaft 2 and the drive pinion 3 are provided with oil supply holes 11 and 12, respectively, so that the lubricating oil splashed on the outer surface passes through the oil supply holes 11 and 12 and is supplied to the pilot needle bearings 9 and 10. It has become.

[Problems to be solved by the device]

By the way, the conditions for supplying the lubricating oil to the pilot needle bearings 9 and 10 are extremely bad. Especially, for supplying the pilot needle bearing 9 that supports the drive pinion 3, the lubricating oil that has passed through the cylindrical roller bearing 8 is guided through the oil supply hole 11. Therefore, it is difficult to supply a sufficient amount of lubricating oil, and therefore, both bearings 9 and 10 have a problem in that initial seizure and surface deviation of rolling surfaces occur at the time of start-up, resulting in poor durability.

Further, with respect to the cylindrical roller bearings 8 supporting the input shaft 2 and the drive pinion 3, the combined load from the gear tooth surface due to the torque transmission during traveling is added, and due to the increase in load and the time lag of lubricating oil supply, There is a problem that surface rolling occurs on the rolling surface and the flange surface together with the initial baking.

Then, the subject of this invention is to make the oil film type on the surface of the rolling elements and the inner and outer rings sufficiently, and to prevent the initial seizure by reducing the torque loss and preventing the temperature rise, and to improve the durability of the vehicle transmission. The purpose is to provide a roller bearing.

[Means for Solving the Problems]

In order to solve the above problems, the present invention provides at least one of a rolling element surface of a roller bearing or a rolling surface of inner and outer rings, or a sliding surface of a roller bearing used for a vehicle transmission,
When an infinite number of minute dents are randomly provided and the surface roughness of the surface provided with the dents is obtained in the axial direction and the circumferential direction and displayed by the parameter RMS, the axial surface roughness RMS
(L) and circumferential surface roughness RMS (C) ratio RMS (L) / RM
The configuration is such that S (C) is 1.0 or less and the surface roughness parameter SK value is -1.6 or less.

[Operation] At least one of the rolling element surface or the rolling surface or the sliding surface of the inner and outer rings is formed into a random minute rough surface, and the finished surface roughness parameter RMS of this minute rough surface is set in the axial direction (L) / RMS.
(C) is set to 1.0 or less, and the parameter SK value is also -1.6.
As described below, the oil film formation rate at the contact portion between the rolling element and the inner and outer races is improved, and the torque loss is reduced and the temperature rise is prevented, seizure is prevented, and the service life is extended.

〔Example〕

An embodiment of the present invention will be described below with reference to the accompanying drawings.

The bearings of the present invention are cylindrical roller bearings, needle bearings, and tapered roller bearings used in automobile transmissions and transaxles. In FIGS. 1 and 2, the cylindrical roller bearings 8 and 8 and the pilot needle bearing 9 described above are used. ,
10 and needle bearings 13 for supporting each gear. In addition, instead of the cylindrical roller bearings 8, 8, tapered roller bearings are used.

In each of the above bearings, at least one of the rolling surfaces of the rolling elements or the rolling surfaces of the inner ring and the outer ring and the inner sliding surfaces of the collars provided at both ends of the inner ring or the outer ring has a minute rough surface a in a random direction.
Is formed in.

This minute rough surface a is obtained by calculating the surface roughness in each of the axial direction and the circumferential direction of each surface and displaying it with the parameter RMS,
The ratio RMS (L) / RMS (C) of the axial surface roughness RMS (L) to the circumferential surface roughness RMS (C) is set to 1.0 or less, for example, 0.7 to 1.0, and the surface roughness parameter SK is set. The value is -1.6 or less in both the axial and circumferential directions.

In the surface processing for obtaining the condition of the minute rough surface a as described above, a desired finished surface can be obtained by special barrel polishing.

The parameter SK value refers to the degree of distortion (SKEWNESS) of the distribution curve of the surface roughness, and the SK value is 0 for a target distribution such as a Gaussian distribution, but the parameter SK value is set in both the circumferential direction and the axial direction. The setting value of -1.6 or less is a range where the shape and distribution of the surface recesses are advantageous for oil film formation.

Next, about the result of the life test performed using the tapered roller bearings B and C in which the surface of the rolling element is provided with a minute rough surface a and the conventional tapered roller bearing A in which the surface of the rolling element is finished to be smooth. explain.

The tapered roller bearings A, B, and C used in the life test are
The outer ring has an outer diameter of 72 mm and the inner ring has an inner diameter of 30 mm.

The surface of the rolling element in the conventional tapered roller bearing A is processed by applying a super finish after grinding,
The surfaces of the rolling elements of the tapered roller bearings B and C according to the present invention are formed into a minute rough surface a by barrel polishing special processing.

By the way, Fig. 3 shows the finished surface condition of standard rollers,
FIG. 4 shows a comparison of the finished surface conditions of the micro-roughening applied to the rolling element surface or the rolling surface of the inner and outer races.

The test equipment used was a radial load tester 21 as shown in the schematic drawing of FIG. 5, with test bearings A or B and C mounted on both sides of a rotary shaft 22 to apply rotation and load. It is a test.

The test conditions are as follows.

Bearing radial load 1800kbf Inner ring speed 3050rpm Lubricating oil Turbine oil Fig. 6 shows the results of rolling element life tests conducted on each test bearing under the above conditions.

As is clear from the above test results, compared with the conventional tapered roller bearing A, the tapered roller bearings B and C of the present invention are compared.
Showed a long life.

In addition, peeling damage was often seen on the side of the finished surface when rolling the finished surface and the rough surface, but this was not observed in the test bearings B and C of the present invention.

7 and 8 show the SK values, R of both test bearings A, B and C.
The result of having obtained L / C and life (L ₁₀ ) of MS is shown.

As shown in FIG. 7, the test bearing B having an SK value of −1.6 or less has a long life.

Further, it has been found that the axial roughness RMS (L / C) has a long life even with the barrel polishing special processing of 1.0 as shown in FIG.

Next, Table 1 shows the calculated values of the oil film parameter Λ based on the Grubbin's equation based on the combination of the rollers of the test bearings A, B, and C and the inner ring rolling surface under the above test conditions.

Generally, the oil film parameter and the oil film formation rate have the relationship shown in Fig. 9, and it is said that the larger the oil film parameter, the better from the viewpoint of life. However, as is clear from the life test results, only Λ Can't explain.

Regarding the confirmation of the oil film formation on the finished surface of the rolling element and the peeling resistance, a test piece having the same surface condition as the test bearing B and the test bearing A of the present invention was used under free rolling conditions using a two-cylinder tester. An accelerated peeling test was conducted using the above.
The confirmation of the oil film formation state was performed by the direct current energization method.

Test conditions Maximum contact surface pressure 227f / mm ² Wind speed 4.2m / sec (2000rpm) Lubricant Turbine oil Number of repeated load 4.8 × 10 ⁵ (4hr) The oil film formation rate by this test is shown in Fig. 10 and Fig. 11. As compared with the test bearing A, the oil film formation rate on the finished surface of the test bearing B of the present invention was improved by about 20% at the start of operation.

It was also confirmed that an oil film was formed almost completely when the number of repeated loadings was 1.2 × 10 ⁵ .

Further, on the finished surface of the test bearing A, many peelings having a length of about 0.1 mm were observed and developed, whereas on the finished surface of the test bearing B of the present invention, no damage was observed. Although data was omitted, the bearing C had the same effect, and neither peeling nor damage was observed.

Next, in order to confirm the oil film formation condition of the tapered roller bearing,
12 and 13 show the results of the measurement of the bearing rotating torque performed using the above test bearings A and B.

The tapered roller rolling element in the test bearing B of the present invention has random minute rough surfaces formed on the entire outer surface including the large-diameter end surface that contacts the flange of the inner ring.

As is clear from FIGS. 12 and 13, the tapered roller bearing of the present invention has a rotational torque reduced by about 30% as compared with the conventional standard bearing. Especially, the effect is great in the low speed and large load region where it is difficult to form an oil film.

Next, FIG. 14 and FIG. 14 show the results of the seizure resistance test with a small amount of lubricating oil using the above test bearings A and B.

The seizure resistance _{test, F a = 800kgf, n =} 3000rpm, under conditions of lubricating gear oil film 1cc coating is a result of judgment upon reaching twice the initial torque value, as compared with the conventional test bearing A It can be seen that the test bearing B of this invention has approximately twice the seizure resistance. Also in the bearing C, it is confirmed that the torque reduction and seizure resistance are about the same.

〔effect〕

As described above, according to the present invention, at least one of the contact surfaces of the rolling elements and the inner and outer rings in the roller bearing for a vehicle transmission is formed into a random minute rough surface, and the roughness of this minute rough surface falls within a low range. Since it has been suppressed to, there are the effects listed below.

(I) An oil film is easily formed on a random micro-rough surface, and since the micro recesses serve as an oil reservoir, an oil film can be reliably formed on the contact portion between the rolling element and the inner and outer races, and torque during rotation can be reduced. You can

(II) Since an oil film can be formed efficiently and reliably on the rolling element surface or the rolling and sliding surfaces of the inner and outer rings, it is possible to improve the seizure resistance of the roller bearing for transmission, which is difficult to supply lubricating oil. Moreover, it is possible to prevent seizure due to a time lag around oil.

(III) Since an oil film can be reliably formed, torque and temperature rise can be reduced.

(IV) The durability can be improved by reducing the torque and improving the seizure resistance.

(V) In a bearing used under preload, it is possible to increase the amount of preload when assembling the transaxle, and it is possible to increase torque and seizure resistance due to excessive preload at low temperatures, as well as high temperature. It is possible to prevent loss of preload at the time.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of use of a roller bearing for a transmission according to the present invention, FIG. 2 is an enlarged sectional view of an essential part of the same, and FIGS. 3 and 4 show a finish state of a rolling element surface. Schematic drawing, FIG. 5 is a schematic drawing of the test equipment, FIG. 6 is a graph showing the results of rolling element life test, FIG. 7 is a graph showing the relationship between SK value and life, and FIG. 8 is RMS (L / C). ) Value vs. life graph, FIG. 9 is a relationship diagram showing oil film parameter and oil film formation rate, FIGS. 10 and 11 are graphs showing oil film formation rate, and FIGS. 12 and 13 are conventional graphs. Graphs showing the measurement results of the rotational torque of the tapered roller bearing and the tapered roller bearing of the present invention, and FIGS. 14 and 15 are graphs showing the results of the seizure resistance test. 2 ... Input shaft, 3 ... Drive pinion, 4 ... Output shaft, 8 ... Cylindrical roller bearing, 9, 10 ... Pilot needle bearing.

Claims (1)

[Scope of utility model registration request] 1. An infinite number of minute recesses are randomly provided on at least one of a rolling element surface of a bearing used for an automobile transmission or a rolling surface and a sliding surface of inner and outer rings,
When the surface roughness of the surface provided with the indentations is obtained in the axial direction and the circumferential direction and displayed by the parameter RMS, the axial surface roughness RMS (L) and the circumferential surface roughness RMS (C) And a ratio RMS (L) / RMS (C) of 1.0 or less, and a surface roughness parameter SK value of −1.6 or less.