JPH09280336A - Lock-up clutch for torque converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lock-up clutch of a torque converter in which a speed characteristic of a frictional coefficient of a wet-type frictional engaging member shows a characteristic to increase the frictional coefficient as a speed of it is increased, i.e., a μ-v characteristic can be applied as a positive gradient in order to prevent a lock-up judder. SOLUTION: A frictional opposing surface 40 of a vertical wall section at an inner surface of a converter cover 14 press contacted when a wet-type frictional member 36 is locked up in a lock-up clutch of a torque converter is provided with an arcuate groove 44 extending in the circumferential direction so as to cross over all the sections where a plurality of installation hubs 42 are fixed to a rear side (an outside part). Then, the wet-type frictional member 36 is provided with a plurality of grooves extending in the radial direction which overlap the circumferential groove at the inner surface of the converter cover and are released only against one of the outer circumferential end surface or the inner circumferential end surface, and a space between the adjoining diametral grooves is shorter than a length of a circumferential groove at the inner surface of the converter cover.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lockup clutch for a torque converter used in an automatic transmission.

[0002]

2. Description of the Related Art Generally, an automatic transmission mounted on a vehicle is designed so that engine rotation is input through a torque converter.
New edition Automotive Engineering Handbook (June 1987: Published by Japan Society of Automotive Engineers), 5th edition, pp. 1-18, lockup clutch for directly connecting the engine and the output shaft as disclosed in FIGS. Some are now equipped with a (direct coupling clutch).

FIG. 11 shows a sectional view of a torque converter equipped with such a lockup clutch. First, the structure will be described. The lockup clutch 10 of the torque converter is integrally built in the torque converter 12.

The torque converter 12 includes a converter cover 14 forming an outer shell and the converter cover 14
A pump impeller 16 fixed to the turbine impeller 16 and a turbine runner 18 arranged to face the pump impeller 16.
It is composed of a stator 20 arranged between the pump impeller 16 and the turbine runner 18.

The turbine runner 18 is spline-fitted to the input shaft 22 of the automatic transmission, which is the output shaft of the torque converter 12, via a turbine hub, and the turbine runner 18 and the input shaft 22 are rotated integrally. It is like this.

The stator 20 is fitted to the input shaft 22 via a one-way clutch 26, and when there is a rotation difference in the forward direction between the pump impeller 16 and the turbine runner 18, the stator 20 is driven by the turbine. It has a function of further accelerating the flow of hydraulic oil that transmits the rotational force to the runner 18 and increasing the torque transmitted to the turbine runner 18.

The lockup clutch 10 has an annular wet friction material 36 fixed to the outer peripheral edge of a lockup piston 30 fixed to the turbine hub 24 via rivets 28, and the lockup piston 30. Are opposed to each other by a frictional opposing surface 40 of a vertical wall portion of the converter cover 14, and engagement, slippage and release of the lockup clutch 10 are controlled by pressure supplied to the piston chamber 32. .

That is, in the piston chamber 32, an oil passage 38 penetrating the central portion of the input shaft 22 is provided.
Lock-up control oil pressure P from the control valve (not shown)
2 is supplied, and when this lockup control hydraulic pressure is drained, the converter cover 1
4, the wet friction material 36 is brought into pressure contact with and is fastened to the friction mating surface 40 of the vertical wall portion of the converter cover 14 by the operating oil pressure P1 outside the piston chamber 32 to be in a lockup state.

When the lockup control oil pressure P2 higher than the operating oil pressure P1 is supplied, the wet friction material 3 is used.
6 is a frictional partner surface 4 of the vertical wall portion of the converter cover 14.
It is released from 0 and unlocked.

A damper 34 is provided on the lock-up piston 30, and the torque transmitted to the lock-up piston 40 is transmitted to the input shaft 22 via the buffer function of the damper 34. Has become. By the way, the converter cover is filled with automatic transmission hydraulic fluid as a torque transmission medium, and the lock-up clutch is used while being immersed in the hydraulic fluid.

[0011]

However, in such a conventional lockup clutch of the torque converter, the power is rotated by being mounted on the drive plate of the engine by the mounting boss 42 fixed to the converter cover 14. Is entered. The wet friction material 36 fixed to the lock-up piston 30 is pressed against the friction surface 4 of the converter cover 14.
There is one in which the mounting boss 42 is present on the back side (outer side) of 0. Since there is undulation on the friction surface, when slip control of the lock-up clutch is performed, the speed characteristic of the friction coefficient between the wet friction material and the metal surface is such that the friction coefficient decreases as the speed increases. Characteristic i.e.
There is a problem that the v-negative gradient becomes remarkable and lockup judder, that is, vibration in the rotation direction occurs.

The present invention has been made by paying attention to such a conventional problem, and in order to prevent lock-up judder, the velocity characteristic of the friction coefficient of the wet friction engagement member causes friction as the velocity increases. An object of the present invention is to provide a lockup clutch for a torque converter in which the coefficient increases, that is, the μ-v characteristic has a positive gradient.

[0013]

A lockup clutch for a torque converter according to the present invention comprises a converter cover to which power rotation from an engine is transmitted and a lockup piston which is rotated integrally with an output shaft of the torque converter. , A wet friction material is fixedly provided on the outer peripheral edge portion of the lockup piston, and the wet friction material is pressed against the inner surface of the converter cover, so that the rotation of the converter cover is directly input to the output shaft, and the power rotation from the engine is It is input by mounting a plurality of mounting bosses fixed to the converter cover to the drive plate of the engine, and the wet friction material is brought into pressure contact during lockup. To
In a lockup clutch of a torque converter that has a mounting boss, a plurality of mounting bosses are fixed to the back side (outside) on the friction mating surface of the vertical wall portion of the inner surface of the converter cover where the wet friction material is pressed against during lockup. An arc-shaped groove extending in the circumferential direction is provided so as to cross all the installed parts.The wet friction material overlaps with the circumferential groove on the inner surface of the converter cover and either the outer peripheral end surface or the inner peripheral end surface is formed. It is characterized in that a plurality of radially extending grooves that are open only to the inner side are provided, and the interval between adjacent radial grooves is shorter than the length of the circumferential groove on the inner surface of the converter cover.

[0014]

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

FIG. 1 is a sectional view showing a lockup clutch of a torque converter according to a first embodiment of the present invention. FIG. 2 is a front view showing a friction mating surface of a converter cover of the torque converter according to the first to tenth embodiments of the present invention, and FIG. 3 shows a torque converter according to the first to tenth embodiments of the present invention. FIG. 6 is an enlarged cross-sectional view of an essential part showing a converter cover, and FIG. 6 is an enlarged front view of an essential part showing the groove shape of the wet friction material according to the first embodiment and the fourth to eleventh embodiments of the present invention.

(First Embodiment) First, the structure of the first embodiment will be described. The conventional structure is that the lockup clutch 10 of the torque converter is integrally formed inside the torque converter 12. Similar to the example, the numbers of the respective parts are the same as those in FIG. 11. In the first embodiment, the wet friction material 36 fixedly provided on the outer peripheral edge portion of the lockup piston 30 is brought into pressure contact with the lockup piston 30 at the time of lockup.
Four mounting bosses 42 are fixed at 90 ° intervals on the back side of the. This point and the size of the mounting boss 42,
The shape and position are the same in the first to eleventh embodiments and comparative examples 1 to 7 described later.

In the first embodiment, the wet friction material 36 fixed to the outer peripheral edge of the lockup piston 30 is used.
Is attached to the friction mating surface 40 of the vertical wall portion of the converter cover 14 that is pressed against the lockup time.
An arcuate groove 44 is provided so that 2 crosses the portion fixed to the back side. Then, this groove 44 has a total of 4 so that it crosses all the back sides of the mounting bosses 42 at four locations.
Books have been formed. The external dimensions of the wet friction material 36 are φ.
234 mm, inner diameter φ208 mm, wet friction material 3
The width of 6 is 13 mm. The size of the friction partner surface 40 is also equal to this. In addition, the length of the groove defined in FIG. 2 and FIG.
As shown in Table 1, the angle of the arc is 20 ° and the length L1 of the arc is 39 mm. Further, as shown in Table 1, the width of the groove is 2.6 mm and the depth is 0.5 mm.

The wet friction material 36 has grooves 3 extending in the radial direction.
8 are evenly spaced around the circumference of 18 °, so that the grooves 38
The distance between the adjacent ones is shorter than the length of the circumferential groove 44 provided on the inner surface of the converter cover. This groove 3
No. 8 is open to the outside of the wet friction material only at the outer peripheral end face and has a length L3 of 8 mm, so that it overlaps with the circumferential groove 44 on the inner surface of the converter cover. The width c of the groove 38 is 2 mm.

(Second Embodiment) FIG. 7 shows a second embodiment of the present invention.
FIG. 6 is an enlarged front view of a main part showing the groove shape of the wet friction material in the embodiment. The difference between the second embodiment and the first embodiment is that, as shown in Table 1 and FIG. 6, the radial groove 38 provided in the wet friction material 36 has a wet friction material only on the inner peripheral end surface. It is only open to the outside. Other points,
That is, the shape, the length, the width, the depth, the number, and the position of the arcuate groove 44 provided on the friction mating surface 40 of the vertical wall portion of the converter cover 14, the size and shape of the wet friction material 36, and
The number, spacing, length and width of the radial grooves 38 provided in the wet friction material 36 are all the same as in the first embodiment. Therefore, the radial grooves 38 provided on the wet friction material 36 overlap the circumferential grooves 44 on the inner surface of the converter cover, and the distance between adjacent grooves 38 is provided on the inner surface of the converter cover. It is shorter than the length of the circumferential groove 44.

(Third Embodiment) FIG. 8 shows a third embodiment of the present invention.
FIG. 6 is an enlarged front view of a main part showing the groove shape of the wet friction material in the embodiment. The difference between the third embodiment and the first embodiment is that, as shown in Table 1 and FIG. 7, half of the radial grooves 38 provided in the wet friction material 36 are wet friction materials only on the outer peripheral end face. Of the wet friction material, half of which are open to the outside of the wet friction material only on the inner peripheral end face, and which are open to the outside only on the outer peripheral end face and to the outside only on the inner peripheral end face. This is the point where and alternate. Other points, namely, the shape, the length, the width, the depth, the number, the position, and the size and shape of the wet friction material 36 of the arc-shaped groove 44 provided on the friction partner surface 40 of the vertical wall portion of the converter cover 14. ,as well as,
The number, spacing, length and width of the radial grooves 38 provided in the wet friction material 36 are all the same as in the first embodiment. Therefore, the radial grooves 38 provided on the wet friction material 36 overlap the circumferential grooves 44 on the inner surface of the converter cover, and the distance between adjacent grooves 38 is provided on the inner surface of the converter cover. It is shorter than the length of the circumferential groove 44.

(Fourth Embodiment) The difference between the fourth embodiment and the first embodiment is that, as shown in Table 1, the radial groove 38 provided in the wet friction material 36 is 40 at 9 ° intervals
Only the point that the book is provided. Other points, namely, the shape, the length, the width, the depth, the number, the position, and the size and shape of the wet friction material 36 of the arc-shaped groove 44 provided on the friction partner surface 40 of the vertical wall portion of the converter cover 14. The radial groove 38 provided on the wet friction material 36 is open to the outside only at the outer peripheral end face, and the length and width of the radial groove 38 are all the first.
It is the same as the embodiment. Therefore, the wet friction material 36
The radial groove 38 provided on the inner surface of the converter cover overlaps with the circumferential groove 44 on the inner surface of the converter cover. The distance between adjacent grooves 38 is larger than the length of the circumferential groove 44 on the inner surface of the converter cover. It's getting shorter.

(Fifth Embodiment) The difference between the fifth embodiment and the first embodiment is that, as shown in Table 1, the radial grooves 38 provided in the wet friction material 36 are 3 at 12 ° intervals
The only point is that there are zero. The other point:
The shape, length, width, depth, number of arc-shaped grooves 44 provided on the friction counterpart surface 40 of the vertical wall portion of the converter cover 14,
The position, the size and shape of the wet friction material 36, the point that the radial groove 38 provided in the wet friction material 36 is open outward only at the outer peripheral end surface, and the length and width of the radial groove 38 are all This is the same as in the first embodiment. Therefore, the wet friction material 3
The radial groove 38 provided in 6 overlaps with the circumferential groove 44 on the inner surface of the converter cover.
The interval between the adjacent ones is shorter than the length of the circumferential groove 44 provided on the inner surface of the converter cover.

(Sixth Embodiment) The difference between the sixth embodiment and the first embodiment is that, as shown in Table 1, the length of the radial groove 38 provided in the wet friction material 36 is long. Is as long as 10 mm. Other points, namely, the shape, the length, the width, the depth, the number, the position, and the size and shape of the wet friction material 36 of the arc-shaped groove 44 provided on the friction partner surface 40 of the vertical wall portion of the converter cover 14. The radial groove 38 provided on the wet friction material 36 is open to the outside only at the outer peripheral end face, and the width, the number, and the interval of the radial groove 38 are all the first.
It is the same as the embodiment. Therefore, the wet friction material 36
The radial groove 38 provided on the inner surface of the converter cover overlaps with the circumferential groove 44 on the inner surface of the converter cover. The distance between adjacent grooves 38 is larger than the length of the circumferential groove 44 on the inner surface of the converter cover. It's getting shorter.

(Seventh Embodiment) The difference between the seventh embodiment and the first embodiment is that the width of the radial groove 38 provided in the wet friction material 36 is as shown in Table 1. Is as wide as 3 mm. Other points, namely, the shape, the length, the width, the depth, the number, the position, and the size and shape of the wet friction material 36 of the arc-shaped groove 44 provided on the friction partner surface 40 of the vertical wall portion of the converter cover 14. The radial groove 38 provided in the wet friction material 36 is open to the outside only at the outer peripheral end face, and the length, the number, and the interval of the radial groove 38 are all the same as those in the first embodiment. Is. Therefore, the radial grooves 38 provided on the wet friction material 36 overlap the circumferential grooves 44 on the inner surface of the converter cover, and the distance between adjacent grooves 38 is provided on the inner surface of the converter cover. It is shorter than the length of the circumferential groove 44.

(Eighth Embodiment) The difference between the eighth embodiment and the first embodiment is that the width of the radial groove 38 provided in the wet friction material 36 is as shown in Table 1. Is as wide as 4 mm. Other points, namely, the shape, the length, the width, the depth, the number, the position, and the size and shape of the wet friction material 36 of the arc-shaped groove 44 provided on the friction partner surface 40 of the vertical wall portion of the converter cover 14. The radial groove 38 provided in the wet friction material 36 is open to the outside only at the outer peripheral end face, and the length, the number, and the interval of the radial groove 38 are all the same as those in the first embodiment. Is. Therefore, the radial grooves 38 provided on the wet friction material 36 overlap the circumferential grooves 44 on the inner surface of the converter cover, and the distance between adjacent grooves 38 is provided on the inner surface of the converter cover. It is shorter than the length of the circumferential groove 44.

(Ninth Embodiment) The difference between the ninth embodiment and the first embodiment is that, as shown in Table 1, the friction mating surface 40 of the vertical wall portion of the converter cover 14 is different. The only difference is that the provided circular arc-shaped groove 44 has a width of 1.3 mm and a depth of 1 mm. Other points,
That is, the shape, the length, the number, and the number of the arc-shaped grooves 44 provided on the friction counterpart surface 40 of the vertical wall portion of the converter cover
The position, the size and shape of the wet friction material 36, the point that the radial groove 38 provided in the wet friction material 36 is open outward only at the outer peripheral end surface, and the length, width, and number of the radial groove 38, The intervals are all the same as in the first embodiment. For this reason,
The radial grooves 38 provided on the wet friction material 36 overlap the circumferential grooves 44 on the inner surface of the converter cover, and the distance between adjacent ones of the grooves 38 is the circumferential groove provided on the inner surface of the converter cover. It is shorter than the length of 44.

(Tenth Embodiment) The difference between the tenth embodiment and the first embodiment is that, as shown in Table 1, the friction mating surface 4 of the vertical wall portion of the converter cover 14 is
The length of the arc-shaped groove 44 extending in the circumferential direction at 0 is as long as 33 ° as the angle of the arc and 65 mm as the length of the arc, and the radial groove 38 provided on the wet friction material 36 is adjacent. The point is that the distance between them is 30 °. Other points, that is, the shape, width, depth, number and position of the arcuate grooves 44 provided on the friction counterpart surface 40 of the vertical wall portion of the converter cover 14, the size, shape and wet friction of the wet friction material 36. The radial groove 38 provided on the material 36 is open outward only at the outer peripheral end face, and the width and number of the radial groove 38,
The intervals are all the same as in the first embodiment. Therefore, the radial grooves 38 provided on the wet friction material 36 overlap the circumferential grooves 44 on the inner surface of the converter cover, and the distance between adjacent grooves 38 is provided on the inner surface of the converter cover. It is shorter than the length of the circumferential groove 44.

(Eleventh Embodiment) FIG. 4 is a front view showing a friction mating surface of a converter cover of a torque converter according to an eleventh embodiment, and FIG. 5 is an eleventh embodiment of the present invention. 3 is an enlarged cross-sectional view of a main part showing a converter cover of the torque converter in FIG.

In the eleventh embodiment, as shown in Table 1, the friction mating surface 4 of the vertical wall portion of the converter cover 14 is used.
0, two arc-shaped grooves 4 arranged side by side substantially concentrically so as to cross the portion where the mounting boss 42 is fixed on the back side.
4 are provided, and a total of eight grooves 44 are formed so as to cross all the back sides of the mounting bosses 42 at four places, and the width of the groove is 1.3 mm, which is the same as the first embodiment. Is different. Further, the outer peripheral edge of the outer groove is located on the outer peripheral side by 1.5 mm from the groove of the first embodiment, and the inner peripheral edge of the inner groove is located on the outer peripheral side by 1.7 mm from the groove of the first embodiment. It is also different from the first embodiment in that it is located and the radial groove 38 provided in the wet friction material 36 has a long length of 10 mm. In other respects, that is, the shape and depth of the arc-shaped groove 44 provided on the friction partner surface 40 of the vertical wall portion of the converter cover 14 are the same as those in the first embodiment, and the length of the groove 44 is also the same. The point that the angle of the arc is 20 ° is the same as that of the first embodiment. Further, the size and shape of the wet friction material 36, the point that the radial groove 38 provided in the wet friction material 36 is open to the outside only at the outer peripheral end surface, and the width, number, and interval of the radial grooves 38 are All are the same as in the first embodiment. Therefore, the radial grooves 38 provided on the wet friction material 36 overlap the circumferential grooves 44 on the inner surface of the converter cover, and the distance between adjacent grooves 38 is provided on the inner surface of the converter cover. It is shorter than the length of the circumferential groove 44.

Comparative Example 1 (Conventional Example) Comparative Example 1 is shown in Table 1.
As shown in FIG. 5, a groove is formed in the frictional partner surface 40 of the vertical wall portion of the converter cover 14 to which the wet friction material 36 fixedly provided on the outer peripheral edge portion of the lockup piston 30 is brought into pressure contact during lockup. Absent. No groove is formed on the wet friction material 36. The size and shape of the wet friction material 36 are the same as those in the first embodiment.

(Comparative Example 2) In Comparative Example 2, as shown in Table 1, the wet friction material 36 fixedly provided on the outer peripheral edge of the lockup piston 30 of the converter cover 14 to which the wet friction material 36 is brought into pressure contact during lockup. As in Comparative Example 1, the groove is not formed on the friction partner surface 40 of the vertical wall portion. A groove 38 extending in the radial direction is formed in the wet friction material 36. The size and shape of the wet friction material 36, and the radial groove 38 provided in the wet friction material 36 are open to the outside only at the outer peripheral end surface. The points, and the length, width, number, and spacing of the radial grooves 38 are the same as those in the first embodiment.

(Comparative Example 3) As shown in Table 1, Comparative Example 3 is the same as Comparative Example 1 in that no groove is formed in the wet friction material 36. The shape, length, width, depth, number, and position of the arcuate grooves 44 provided on the friction counterpart surface 40 of the vertical wall portion of the converter cover 14 are the same as those in the first embodiment.

(Comparative Example 4) In Comparative Example 4, as shown in Table 1, the radial groove 38 provided in the wet friction material 36 was set at 36 °.
Only 10 points are provided at intervals, which is different from the first embodiment. Other points, namely, the shape, length, width, depth, number, position, size, shape of the wet friction material 36 of the arc-shaped groove 44 provided on the friction counterpart surface 40 of the vertical wall portion of the converter cover 14. The radial groove 38 provided in the wet friction material 36 is open outward only at the outer peripheral end face, and the length and width of the radial groove 38 are all the same as those in the first embodiment. . Therefore, the radial groove 38 provided in the wet friction material 36 is provided.
Is designed to overlap the circumferential groove 44 on the inner surface of the converter cover, but the interval between adjacent ones of the grooves 38 is longer than the length of the circumferential groove 44 provided on the inner surface of the converter cover.

(Comparative Example 5) In Comparative Example 5, as shown in Table 1, the radial groove 38 provided in the wet friction material 36 has a length of 4 mm.
Only the short point of mm is different from the first embodiment. At other points, namely, the shape and length of the arc-shaped groove 44 provided on the friction counterpart surface 40 of the vertical wall portion of the converter cover 14,
Width, depth, number, position, dimensions and shape of the wet friction material 36,
The radial groove 38 provided in the wet friction material 36 is open outward only at the outer peripheral end face, and the width of the radial groove 38,
The number and intervals are all the same as in the first embodiment.
For this reason, the distance between the adjacent radial grooves 38 provided on the wet friction material 36 is shorter than the length of the circumferential groove 44 provided on the inner surface of the converter cover.
8 does not overlap the circumferential groove 44 on the inner surface of the converter cover.

Comparative Example 6 In Comparative Example 6, as shown in Table 1, the radial groove 38 provided in the wet friction material 36 penetrates both the inner peripheral end surface and the outer peripheral end surface and is open. Therefore, the groove 38 is different from the first embodiment only in that the length of the groove 38 is as long as 13 mm. Other points, namely, the shape, the length, the width, the depth, the number, the position, and the size and shape of the wet friction material 36 of the arc-shaped groove 44 provided on the friction partner surface 40 of the vertical wall portion of the converter cover 14. The width, number and spacing of the radial grooves 38 provided in the wet friction material 36 are all the same as in the first embodiment. Therefore, the interval between the adjacent radial grooves 38 provided on the wet friction material 36 is shorter than the length of the circumferential groove 44 provided on the inner surface of the converter cover.
Overlaps with the circumferential groove 44 on the inner surface of the converter cover.

Comparative Example 7 As shown in Table 1, Comparative Example 7 is different only in that the radial groove 38 provided in the wet friction material 36 is not opened to both the inner peripheral end surface and the outer peripheral end surface. This is different from the first embodiment. Other points, namely, the shape, the length, the width, the depth, the number, the position, and the size and shape of the wet friction material 36 of the arc-shaped groove 44 provided on the friction partner surface 40 of the vertical wall portion of the converter cover 14. The length, width, number, and interval of the radial grooves 38 provided in the wet friction material 36 are all the same as in the first embodiment. Therefore, the interval between the adjacent radial grooves 38 provided on the wet friction material 36 is shorter than the length of the circumferential groove 44 provided on the inner surface of the converter cover, and the groove 38 extends in the circumferential direction on the inner surface of the converter cover. The groove 44 overlaps.

(Performance Evaluation Test) Since the friction characteristics of the lockup clutches of the torque converters of the first to eleventh embodiments and comparative examples 1 to 7 are compared, no influence is exerted as a fluid joint of the torque converter. As described above, the torque converter 12 including the lockup clutch 10 of the first to 11th embodiments and the comparative examples 1 to 7 and having the vanes of the pump impeller 16, the turbine runner 18, and the stator 20 removed was prototyped. This prototype torque converter was mounted on an evaluation tester (not shown) and the friction performance of each lockup clutch was compared. At this time,
In order to obtain a predetermined surface pressure, the pressure difference between the working oil pressure P1 and the lockup control oil pressure P2 is measured at a constant value, and the friction coefficient is calculated from the output shaft torque and the measured values of P1 and P2. did.

Friction characteristics include a sliding speed of 0.2 m / s.
Coefficient of friction (abbreviated as μ0.2) and sliding speed 2
The friction coefficient at m / s (abbreviated as μ2) was measured, and μ0.
1 divided by μ2 / μ2, which is a value obtained by dividing 2 by μ2.
The friction characteristics of the first embodiment and Comparative Examples 1 to 3 were evaluated.

That is, if the value of μ0.2 / μ2 is larger than 1, then μ0.2> μ2, which means that the friction coefficient decreases as the speed increases, indicating a μ-v negative gradient.
If the value of 0.2 / μ2 is smaller than 1, μ0.2 <μ2, which means that the μ-v positive gradient is obtained. This μ 0.2
If / μ2 is larger than a certain level, it may cause self-excited vibration due to friction, so if the value of μ0.2 / μ2 is small, μ
It can be evaluated that the −v characteristic is good. The condition for generating self-excited vibration is not determined only by the μ-v characteristic of the lockup clutch 10, but also depends on the vibration mass of the system, the spring constant, the strength of the damper action, etc. Since the size also varies depending on the unit, vehicle, etc. used, the required value of μ0.2 / μ2 varies depending on the environment of the unit, vehicle, etc. in which the lockup clutch is used, and should be uniquely determined. I can't.

As the wet friction material 36 used in this friction performance test, a paper type wet friction material of the same material is used in each of the embodiments and the comparative examples. In addition, the test conditions for this friction performance test are: the surface pressure of the wet friction material: 1 MPa,
Oil temperature at the time of test: 80 ° C was adopted, Nissan genuine Nissanmatic Fluid D was used as test oil, and sliding speed was 0.
The test was conducted after running-in for 30 minutes at 6 m / s.

The results of these tests are shown in Table 1. As is apparent from this table, the lockup clutches of the torque converters according to the first to eleventh embodiments of the present invention have the friction of the vertical wall portion of the inner surface of the converter cover 14 against which the wet friction material 36 is pressed during lockup. The mating surface 40 is provided with an arc-shaped groove 44 extending in the circumferential direction so that a plurality of mounting bosses 42 cross all the portions fixed to the back side (outer side), and the wet friction material 36 is provided with: A plurality of radially extending grooves 38, which overlap the circumferential groove 44 on the inner surface of the converter cover 14 and open to only one of the outer peripheral end surface or the inner peripheral end surface, are provided. Is shorter than the length of the circumferential groove 44 on the inner surface of the converter cover 14, the friction coefficient ratio μ0.2 / μ2 has an excellent μ-v characteristic of 0.95 to 0.99. It was.

On the other hand, in Comparative Examples 1 to 3, unlike the first to 11th embodiments, the mounting boss 42 of the friction partner surface 40 of the vertical wall portion of the inner surface of the converter cover 14 is fixed to the back side (outside). Lacking an arcuate groove 44 extending in the circumferential direction that crosses all the provided parts, or
Either the wet friction material 36 lacks a plurality of radially extending grooves 38 that overlap the circumferential groove 44 on the inner surface of the converter cover 14 and open to only one of the outer peripheral end surface and the inner peripheral end surface. Therefore, the friction coefficient ratio μ
0.2 / μ2 is large as 1.04 to 1.07 and shows a μ-v negative gradient, and the μ-v characteristics were inferior to those of the first to eleventh embodiments.

Further, in Comparative Example 4, as in the first to eleventh embodiments, the wet friction material 36 overlaps with the circumferential groove 44 on the inner surface of the converter cover and is formed on only one of the outer peripheral end surface and the inner peripheral end surface. Although a plurality of radially extending grooves 38 that are open to the outside are provided, unlike the first to eleventh embodiments, the distance between adjacent radial grooves 38 is the circumference of the inner surface of the converter cover 14. Since it is longer than the length of the directional groove 44, the friction coefficient ratio μ0.2 / μ2 is as large as 1.03 and shows a μ-v negative gradient, which is a μ-v characteristic as compared with the first to eleventh embodiments. Was inferior.

Further, in Comparative Example 5, as in the first to eleventh embodiments, the wet friction material 36 has a plurality of radial directions open to only one of the outer peripheral end surface and the inner peripheral end surface. An extending groove 38 is provided, and this radial groove 38
Although the distance between adjacent ones is shorter than the length of the circumferential groove 44 on the inner surface of the converter cover 14, unlike the first to eleventh embodiments, the radial groove 38 is a circumferential groove on the inner surface of the converter cover. Since it does not overlap with 44, the friction coefficient ratio μ0.2 / μ2 is as large as 1.03, and μ-v
The negative gradient is shown, and the μ-v characteristics are inferior to those of the first to eleventh embodiments.

Further, in Comparative Example 6, as in the first to eleventh embodiments, the wet friction material 36 is provided with a plurality of radially extending grooves 38, which are adjacent to the radial grooves 38. The distance between the mating members is shorter than the length of the circumferential groove 44 on the inner surface of the converter cover 14, and the radial groove 38 overlaps with the circumferential groove 44 on the inner surface of the converter cover.
Unlike the first to eleventh embodiments, the radial groove 38 penetrates both the outer peripheral end surface and the inner peripheral end surface and is open,
1 and P2 could not be set to a predetermined hydraulic pressure, and the μ-v characteristic could not be measured under the same surface pressure conditions as in the first to eleventh embodiments. It is considered that this is because the hydraulic pressure leaked due to the radial groove that penetrates the inner and outer peripheral end faces.

Further, in Comparative Example 7, as in the first to eleventh embodiments, the wet friction material 36 is provided with a plurality of radially extending grooves 38, which are adjacent to the radially extending groove 38. The distance between the mating members is shorter than the length of the circumferential groove 44 on the inner surface of the converter cover 14, and the radial groove 38 overlaps with the circumferential groove 44 on the inner surface of the converter cover.
Unlike the first to eleventh embodiments, since the radial groove 38 is not opened to either the outer peripheral end face or the inner peripheral end face, the friction coefficient ratio μ0.2 / μ2 is as large as 1.04, and μ-v
The negative gradient is shown, and the μ-v characteristics are inferior to those of the first to eleventh embodiments.

[0047]

[Table 1]

[0048]

As described above, the lockup clutch of the torque converter according to the present invention is a lockup piston that rotates integrally with the converter cover to which the power rotation from the engine is transmitted and the output shaft of the torque converter. A wet friction material is fixedly provided on the outer peripheral edge portion of the lockup piston, and the wet rotation of the wet friction material is brought into pressure contact with the inner surface of the converter cover, whereby the rotation of the converter cover is directly input to the output shaft, and The power rotation is input by attaching a plurality of mounting bosses fixed to the converter cover to the drive plate of the engine, and the wet friction material is pressed against the lockup during the lockup. Lockup of torque converter with mounting boss on back side (outside) In the latch, a plurality of mounting bosses cross all the parts fixed to the back side (outer side) on the friction mating surface of the vertical wall portion of the inner surface of the converter cover where the wet friction material is pressed against during lockup. A circular arc-shaped groove extending in the circumferential direction is provided.The circumferential groove overlaps with the circumferential groove on the inner surface of the converter cover and is open to only one of the outer peripheral end surface and the inner peripheral end surface in the radial direction. It is characterized in that a groove extending to the radial groove is provided, and the interval between adjacent radial grooves is shorter than the length of the circumferential groove on the inner surface of the converter cover, and this structure is used as a means for solving the above-mentioned conventional problems. There is.

Therefore, the frictional characteristics of the lockup clutch of the torque converter can be improved to a μ-v positive gradient in which the friction coefficient increases as the speed increases, and lockup judder at slip lockup can be prevented. That is an excellent effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a lockup clutch of a torque converter of the present invention.

FIG. 2 is a front view of the converter cover relating to the lockup clutch of the torque converter according to the first to tenth embodiments of the present invention, as viewed from the inner surface side.

FIG. 3 is an enlarged cross-sectional view of essential parts showing a converter cover relating to the lockup clutch of the torque converter according to the first to tenth embodiments of the present invention.

FIG. 4 is a front view of a converter cover related to a lockup clutch of a torque converter according to an eleventh embodiment of the present invention, as viewed from the inner surface side.

FIG. 5 is an enlarged sectional view of essential parts showing a converter cover relating to a lockup clutch of a torque converter according to an eleventh embodiment of the present invention.

FIG. 6 is an enlarged front view of an essential part showing the groove shape of the wet friction material according to the first and fourth to eleventh embodiments of the present invention.

FIG. 7 is an enlarged front view of an essential part showing the groove shape of the wet friction material according to the second embodiment of the present invention.

FIG. 8 is an enlarged front view of an essential part showing the groove shape of the wet friction material according to the third embodiment of the present invention.

FIG. 9 is an enlarged front view of an essential part showing the groove shape of the wet friction material of Comparative Example 6.

FIG. 10 is an enlarged front view of essential parts showing the groove shape of the wet friction material of Comparative Example 7.

FIG. 11 is a cross-sectional view showing a lockup clutch of a conventional torque converter.

[Explanation of symbols]

10 Lockup clutch 12 Torque converter 14 Converter cover 16 Pump impeller 18 Turbine runner 20 Stator 22 Input shaft (output shaft) 30 Lockup piston 36 Wet friction material 38 Radial groove provided in wet friction material 40 Friction mating surface 42 Mounting boss 44 Circumferential groove formed on the friction counter surface inside the converter cover

Claims (1)

[Claims] 1. A converter cover to which power rotation from an engine is transmitted, and a lock-up piston that rotates integrally with an output shaft of a torque converter, wherein a wet friction material is provided on an outer peripheral portion of the lock-up piston. Fixed,
When the wet friction material is brought into pressure contact with the inner surface of the converter cover, the rotation of the converter cover is directly input to the output shaft, and the power rotation from the engine causes a plurality of mounting bosses fixed to the converter cover to be attached to the engine. A torque converter in which the mounting boss is provided on the back side (outer side) of the friction mating surface of the vertical wall portion of the inner surface of the converter cover that is input by being mounted on the drive plate and is brought into pressure contact with the wet friction material during lockup. In the lock-up clutch of, the wet friction material is brought into pressure contact with the friction mating surface of the vertical wall portion of the inner surface of the converter cover at the time of lock-up,
A plurality of mounting bosses are provided with arcuate grooves extending in the circumferential direction so as to cross all the parts fixedly provided on the back side, and the wet friction material has a circumferential groove on the inner surface of the converter cover. Providing a plurality of radially extending grooves that are open to either the outer peripheral end face or the inner peripheral end face,
A lock-up clutch for a torque converter, wherein an interval between adjacent radial grooves is shorter than a length of a circumferential groove on the inner surface of the converter cover.