JP2007127261A - Gear and gear drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear and gear drive unit which sufficiently prepares an oil film between teeth surfaces of the gears rotating at high speed and preventing generation of pitching, abrasion, and scoring and improving its durability by preventing a temperature rise and wear. <P>SOLUTION: A large number of fine recessed dents is prepared on a tooth surface at random, an average area of the dents is set to be within a range of 30 to 100 μm<SP>2</SP>, and a Rymax is set to be within a range of 0.4 to 1.0 μm. Thus, the gear acquires a longer life under an extremely thin condition of the oil film at low-viscosity, thin lubrication so that the tooth surface prepares a high oil film forming capability. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gear and a gear driving device, and can be applied to, for example, a gear and a gear driving device used in a power transmission unit of a transmission of an automobile or a gear pump.

For example, Patent Document 1 discloses a gear in which countless dents are randomly provided on a tooth surface. The average area of the minute depressions is 35 to 150 μm ² , the proportion of the minute depressions on the surface is 10 to 40%, the surface roughness Rmax provided with the minute depressions is 0.6 to 2.5 μm on average, The parameter Sk value of the surface roughness of the tooth surface provided with the indentation is set to satisfy Sk ≦ −1.6. As a result, the oil film forming ability on the surface is improved and the oil film between the gear tooth surfaces is sufficiently formed to prevent damage caused by poor lubrication such as peeling from the surface of the gear and improve durability. Yes.
Japanese Utility Model Publication No. 4-56254

  In recent years, gear transmissions and other parts where gears are used are becoming smaller and more powerful, and there is a tendency for the usage environment, such as lower viscosity of the lubricating oil, to increase in load and temperature. For this reason, gears have changed to a more severe lubrication environment than ever, and wear due to poor lubrication and surface-origin type peeling are more likely to occur. That is, with the multi-stage transmission, the torque and load acting on the gears used therein and the rotation speed tend to increase, and the gears are required to have functions such as downsizing and high-speed response. As a result, the lubrication conditions of gears become increasingly severe, and wear and damage due to poor lubrication are likely to occur. Therefore, even if the gear tooth surface conditions are set as described in Patent Document 1, if the oil film thickness is extremely thin under low viscosity and dilute lubrication, the effect cannot be sufficiently exhibited. There is.

  An object of the present invention is to provide a gear that can sufficiently form an oil film between tooth surfaces of a gear that rotates at high speed, prevents occurrence of pitching, abrasion, and scoring, prevents temperature rise and wear, and improves durability. Another object of the present invention is to provide a gear driving device using such a gear.

In order to solve the above-mentioned problems, the gear of the present invention is provided with an infinite number of minute concave depressions on the tooth surface, the average area of the depressions is in the range of 30 to 100 μm ² , and the Rymax is 0.1. It is in the range of 4 to 1.0 μm. The parameter Rymax is the maximum value of the maximum height for each reference length (ISO 4287: 1997).

The gear driving device of the present invention is a gear driving device having a driving gear driven by a driving force and a driven gear driven by meshing with the driving gear.
An infinite number of minute concave recesses are randomly provided on the tooth surfaces of both the drive gear and the driven gear, the average area of the recesses is in the range of 30 to 100 μm ² , and Rymax is 0.4 to 1. It is characterized by being in the range of 0.0 μm.

As described above, in the gear and the gear driving device of the present invention, the average area of the tooth surface recess is defined within the range of 30 to 100 μm ² , and the surface roughness parameter Rymax of the surface provided with the recess is set to 0. Since the oil film forming ability can be improved by setting within the range of 4 to 1.0 μm, a long life can be obtained even under extremely thin oil film conditions under dilute lubrication.

  In this gear and the gear driving device, when the surface roughness of the surface provided with the recess is represented by the parameter Rqni, the ratio of the axial surface roughness Rqni (L) to the circumferential surface roughness Rqni (C) When the value Rqni (L) / Rqni (C) is set to 1.5 or less, the oil film forming ability of the tooth surface can be further improved. The parameter Rqni is the square root of the value obtained by integrating the square of the height deviation from the roughness center line to the roughness curve in the section of the measurement length and averaging it, and is also called the root mean square roughness. . Rqni is obtained by numerical calculation from the cross-sectional curve and roughness curve recorded in an enlarged manner, and is measured by moving the stylus of the roughness meter in the width direction and the circumferential direction.

  As described above, according to the present invention, by providing an infinite number of minute concave concaves, the tooth surface becomes a minute rough surface and an oil film is easily formed. In addition, since this dent becomes an oil reservoir, an oil film can be reliably formed on the sliding surface. As a result, the temperature rise can be reduced, and the metal contact between the tooth surfaces of the meshing gears can be alleviated. Pitting, abrasion, and scoring occur even in the high-speed rotation region. Can be prevented. Therefore, even if the oil film thickness is extremely thin under low viscosity and dilute lubrication, a long life of the gear and the gear driving device can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a transmission used in an automobile. 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 are parallel to the output shaft 4. 6 is arranged, and a gear 7 group is attached to the drive pinion 3 and the shafts 2, 4, 5. By changing the meshing of each gear 7 group by an operation from the outside of the case 1, The insertion is taken out of the output shaft 4 while being shifted or reversed. In this transmission, as the input shaft 2 rotates, oil accumulated in an oil pan (not shown) is splashed onto the gear 7, lubricates the gear 7 group, the bearings 8, 9 and the like, and returns to the oil pan. That is, a gear drive device having a driven gear driven by this combination is provided.

FIG. 2 shows a gear 7 constituting a part of the gear driving device. The tooth surface 7a of this gear is a minute rough surface in which numerous independent minute depressions are randomly formed. The minute rough surface has an indentation average area in the range of 30 to 100 μm ² and Rymax in the range of 0.4 to 1.0 μm. Further, when the surface roughness is obtained in the axial direction and the circumferential direction of each surface and displayed by the parameter Rqni, the ratio of the axial surface roughness Rqni (L) to the circumferential surface roughness Rqni (C) The value Rqni (L) / Rqni (C) is 1.5 or less. As the surface processing for obtaining such a fine rough surface, a desired finished surface can be obtained by special barrel polishing, but not limited thereto, for example, a shot or the like may be used.

As described above, the gear of the gear driving device according to the present invention is provided with an infinite number of minute concave recesses, whereby the tooth surface becomes a minute rough surface and an oil film is easily formed. In addition, since this dent becomes an oil reservoir, an oil film can be reliably formed on the sliding surface. As a result, the temperature rise can be reduced and the metal contact between the tooth surfaces 7a of the meshing gear 7 can be relaxed, and the occurrence of pitching, abrasion and scoring can be prevented even in the high-speed rotation region, and the life can be extended. Can be planned. In particular, by setting the average area of the depressions in the range of 30 to 100 μm ² and setting the surface roughness parameter Rymax of the surface provided with the depressions in the range of 0.4 to 1.0 μm, oil film formation Since the capacity can be improved, a long life can be obtained even under conditions where the oil film thickness is extremely thin under dilute lubrication.

  The oil film forming ability can also be achieved by setting the value Rqni (L) / Rqni (C) of the ratio of the axial surface roughness Rqni (L) and the circumferential surface roughness Rqni (C) to 1.5 or less. Can be improved.

Therefore, the gear of the present invention can obtain a long life even under conditions of low viscosity and dilute lubrication and the oil film thickness is extremely thin, and the gear driving device of the present invention using such a gear has a long life. You can get

  As described above, the gear of the present invention is excellent in pitching resistance, abrasion resistance, and scoring resistance, and is therefore optimal as a gear 7 for an automobile transmission as shown in FIG. In addition, an automatic transmission (AT) for automobiles normally uses two to three sets of planetary gear mechanisms, and has a structure in which the reduction ratio varies by fastening the carrier and ring gear of these planetary gear mechanisms with a clutch. . For this reason, it is preferable to apply the surface properties of the present invention to the sun gear, planetary pinion, ring gear, and the like in such a planetary gear mechanism.

  By the way, in a pair of gears engaged with each other, even if a surface treatment satisfying the surface properties according to the present invention is applied only to the tooth surface of one gear, an effect such as a long life can be sufficiently obtained. It is more effective to subject the surface to surface treatment that satisfies the surface properties according to the present invention.

  Of course, the gear of the present invention can be used in various gear drive devices other than the transmission for automobiles.

In order to show the usefulness of the present invention, first, the life of the gear was evaluated. The tooth surface of the gear makes rolling contact and sliding contact with the tooth surface of the other side, and the contact is in a form according to the contact state between the race of the rolling bearing and the race. Therefore, it is considered that the life evaluation of the gear can be evaluated by the life test evaluation of the rolling bearing. From this viewpoint, the present inventors conducted a life test of the rolling bearing under the conditions described later. Hereinafter, an example of measurement methods and conditions for the parameters Ryni, Rymax, Sk, and Rqni measured in this example will be described. The parameter Ryni is the average value of the maximum height for each reference length, that is, the reference curve is extracted from the roughness curve in the direction of the average line, and the distance between the peak line and the valley line of this extracted part is rough. It is a value measured in the direction of the vertical magnification of the curve (ISO 4287: 1997). The parameter Sk indicates the degree of distortion (skewness) of the roughness curve (ISO 4287: 1997), and is a standard statistic for knowing the asymmetry of the uneven distribution. In a symmetric distribution such as a Gaussian distribution, the Sk value is close to 0, and takes a negative value when the concave and convex portions are deleted, and takes a positive value in the opposite case. When measuring the surface properties represented by these parameters for components such as rolling elements and rolling rings of rolling bearings, even one measured value can be relied on as a representative value. Good.
Parameter calculation standard: JIS B 0601: 1994 (Surfcom JIS 1994)
Cut-off type: Gaussian Measurement length: 5λ
Cut-off wavelength: 0.25mm
Measurement magnification: × 10000
Measurement speed: 0.30 mm / s
Measurement location: Roller center measurement number: 2
Measuring device: Surface roughness measuring device Surfcom 1400A (Tokyo Seimitsu Co., Ltd.)

Further, in order to quantitatively measure the indentation, the roller surface can be enlarged and quantified from the image by a commercially available image analysis system. Furthermore, if the surface texture inspection method and the surface texture inspection apparatus disclosed in Japanese Patent Laid-Open No. 2001-183124 are used, stable and accurate measurement can be performed. This method irradiates the inspection surface having a curvature with light, images the inspection surface with a camera, measures the luminance of the image of the inspection surface imaged with the camera, and measures the bright and dark portions of the measured luminance. A surface texture inspection method for inspecting the surface texture of a surface to be inspected with a light-dark pattern formed with a contrast of light, and irradiating light with matching the optical axis direction of the camera, and the luminance distribution of the measured image has a peak value By positioning the inspection surface so that the position indicating the position coincides with the optical axis of the camera, shading (luminance distribution) due to the curvature of the inspection surface is suppressed. Also, the light is irradiated so as to coincide with the optical axis direction of the camera, and the luminance distribution of the image to be measured is based on the part of the inspection surface corresponding to the position where this luminance distribution shows the peak value, and the symmetry axis of curvature is In the orthogonal two-dimensional coordinates as one axis, approximate the one-dimensional luminance distribution along each orthogonal coordinate axis with an approximate function, and use these approximate functions to remove the luminance distribution of the image. By correcting the brightness of the measured image corresponding to each coordinate position with the peak value of the reference value as the reference value, and inspecting the surface properties of the inspection surface with the brightness pattern of the corrected brightness, it is possible to obtain a light and dark pattern without shading. Surface properties can be inspected. The measurement conditions are as follows, for example. In addition, when measuring the area ratio and the average area of the indentation for components such as rolling elements and rolling rings of rolling bearings, as with the above parameters, a single measured value can be relied on as a representative value. It is good to measure two opposite places.
Area ratio: Percentage of pixels (black) smaller than the binarization threshold ((bright area brightness + dark area brightness) / 2) in the observation visual field range Average area: total black area / total number Observation visual field: 826 μm × 620 μm
Measurement location: Roller center measurement number: 2

FIG. 3 shows an example of a test rolling bearing. The rolling bearing 10 is a needle roller bearing in which a needle roller 12 is incorporated in an outer ring 13 as a rolling element, and the counterpart shaft 14 is supported by the needle roller 12. It is like that. A description will be given of the results of manufacturing a plurality of types of needle roller bearings having surface treatments with different finishing surfaces on the surface of the needle rollers and performing a life test. As shown in FIG. 4, the needle roller bearing used for the life test has 15 outer diameters Dr = 33 mm, inner diameter dr = 25 mm, diameter D = 4 mm of needle roller 12, and length L = 25.8 mm. This is a bearing with a cage 15 using needle rollers. Three types of test roller bearings with different surface roughness finishes were produced. That is, bearing A (comparative example) subjected to superfinish after grinding, bearing B (comparative example), bearing C (reference example), bearing D (reference example) in which numerous indentations of minute concave shapes are randomly formed It is. The finished surface conditions of the needle rollers of each test bearing are shown in FIGS. Specifically, FIG. 5 shows the surface roughness of the bearing A, FIG. 6 shows the surface roughness of the bearing B, and FIG. 7 shows the surface roughness of the bearing C and the bearing D, respectively. Table 1 shows a list of characteristic value parameters of the surface finish of each test bearing. In addition, about Rqni (L / C), the bearings B, C, and D are 1.5 or less, and the bearing A is a value around 1.5. The crystal grain size was measured based on the JIS G 0551 steel austenite grain size test method.

The test apparatus used is a radial load tester 16 as schematically shown in FIG. 8, and the test bearings 10 are attached to both sides of the rotating shaft 17 and the test is performed by applying rotation and load. The finish of the inner race (mating shaft) used for the test is Ra 0.10 to 0.16 μm of the polished finish. The outer race (outer ring) is also common. The test conditions are as follows.
Bearing radial load: 2000kgf
Rotation speed: 4000rpm
Lubricant: Crisecoil H8 (2 cst under test conditions)

  FIG. 9 shows the result of the life test under the oil film parameter Λ = 0.13. The vertical axis of the figure represents the lifetime (h). As shown in the figure, the bearing A was 78h and the bearing B was 82h, whereas the bearing C was 105h and the bearing D was 121h. As is apparent from this data, the bearings C and D, which have been surface-treated so that the surface of the needle roller satisfies the surface shape according to the present invention, are low-viscosity and lean very severe oil film parameter Λ = 0.13. A long life effect can be obtained even under lubricating conditions. Therefore, the gear according to the present invention in which the tooth surface is set in the above numerical range can obtain a high long-life effect.

  Next, a gear pitching test was performed using a spur gear fatigue tester shown in FIG. 10 to evaluate the pitching strength. In FIG. 10, a drive side gear 31 (29 teeth) and a driven side gear 32 (30 teeth) are attached to one side of each rotary shaft 33, 34, and the drive side shaft 33 is a motor (not shown). It is driven by. Further, a torque is applied by a load lever 35 and a weight 36 attached to the drive-side shaft 33. Two types of drive-side gear 31 were prepared depending on whether or not the surface treatment according to the present invention was performed. Details of test conditions and the like are as shown in Table 2.

  The data of the gear pitching test are shown in Tables 3 and 4. Table 3 shows the result (comparative example) in the case where neither the drive-side gear nor the driven-side gear is subjected to surface treatment, and Table 4 shows the surface properties according to the present invention on the tooth surface of the drive-side gear. Table 5 shows the results (Examples) of the case (b) in which the surface treatment was performed so as to satisfy the conditions, and Table 5 shows that the tooth surface of the drive side gear and the driven side gear satisfy the surface properties according to the present invention. (C) results (Examples) are shown in the case of using a surface-treated material. From these, it can be confirmed that the pitching life is improved by 2 times or more in the case of (b) and 3 times or more in the case of (c) compared with the case of (a).

Longitudinal cross section of automobile transmission Enlarged perspective view of essential parts of gear Cross section of needle roller bearing Cross section of needle roller bearing used for life test Roughness curve diagram showing the condition of the finished surface of test bearing A Roughness curve diagram showing the condition of the finished surface of test bearing B Roughness curve diagram showing the finished surface condition in test bearings C and D Partial sectional view of test equipment Graph showing life test results Partial perspective view of spur gear testing machine

Explanation of symbols

2 Input shaft 4 Output shaft 5 Counter shaft 7 Gear 10 Rolling bearing 12 Needle roller

Claims (4)

It is characterized by randomly providing innumerable minute concave depressions on the tooth surface, the average area of the depressions is in the range of 30 to 100 μm ² , and Rymax is in the range of 0.4 to 1.0 μm. Gears to play.   When the surface roughness of the surface provided with the depression is represented by the parameter Rqni, the ratio value Rqni (L) / Rqni (R) of the axial surface roughness Rqni (L) and the circumferential surface roughness Rqni (C) 2. The gear according to claim 1, wherein C) is 1.5 or less. In a gear driving device having a driving gear driven by a driving force and a driven gear driven by meshing with the driving gear,
An infinite number of minute concave recesses are randomly provided on the tooth surfaces of both the drive gear and the driven gear, the average area of the recesses is in the range of 30 to 100 μm ² , and Rymax is 0.4 to 1. A gear driving device characterized by being in a range of 0.0 μm.   When the surface roughness of the surface provided with the depression is represented by the parameter Rqni, the ratio value Rqni (L) / Rqni (R) of the axial surface roughness Rqni (L) and the circumferential surface roughness Rqni (C) 4. The gear driving device according to claim 3, wherein C) is 1.5 or less.

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