JP2007146928A - Lock-up clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lock-up clutch used in a torque converter and capable of improving heat resistance of an outside diameter side friction member for performing slip control. <P>SOLUTION: This drawing is an enlarged cross sectional view of main parts of parts of a front cover 21 and a clutch piston 5 of the lock-up clutch for the torque converter. The friction member is divided into an outside diameter side friction member 71 for performing slip control for making μ-ν characteristic a positive gradient and an inside diameter side friction member 72 having large coefficient of static friction and large torque capacity when engaging the clutch. In this invention, the outside diameter side friction member is further divided into an outer periphery side friction member 71A and an inner periphery side friction member 71B, and each of them is stuck to either of the front cover 21 and the clutch piston 5. Consequently, large quantity of heat generated at slip control time is dispersed onto a front cover 21 side having large heat capacity and high heat radiation effect and a piston 5 side and escapes, thereby increasing heat resistance of the outside diameter side friction member 71. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement of a lockup clutch that is used in a torque converter of an automatic transmission and that can suppress vibration (shudder) caused by stick-slip by slip control.

  FIG. 1 is a cross-sectional view showing a basic configuration of a torque converter having a lock-up clutch. A torque converter 10 includes a pump unit 2, a turbine unit 3, and a stator 4. 21 is a front cover, 22 is an outer shell of the pump unit 2, 23 is a blade, 24 is an inner core, 32 is an outer shell of the turbine unit 3, 33 is a blade, 34 is an inner core, and 35 is a turbine hub. .

  Reference numeral 5 denotes a clutch piston of the lock-up clutch, 51 denotes a damper support portion, 52 denotes a damper, 53 denotes a damper plate portion, and 54 denotes a damper spring. The outer shell 32, the turbine hub 35, and the damper 52 of the turbine unit 3 are connected by a rivet 55. 56 is a hole in the center of the piston 5 through which the turbine hub 35 passes. Reference numeral 7 denotes a friction material attached to the clutch engaging portion of the clutch piston 5. (This friction material may be adhered to the front cover 21 side.) 6 is a connector with the engine welded to the front cover 21. XX represents the center line of the entire torque converter.

  In recent years, the lock-up clutch has been operated from a low vehicle speed range in order to improve fuel efficiency. For this reason, slip control is performed. In this case, the problem with the lock-up clutch device is that the clutch piston becomes a vibrating body and the damper or the like becomes an elastic body to generate vibration (referred to as shudder) due to stick-slip of the friction material.

  The friction material is composed of fibers and a resin dissolved in a solvent. When the solvent volatilizes, the resin inside moves together with the solvent near the surface. When a high resin layer is formed and the slip rotational speed is low, the friction coefficient is high, and when the slip rotational speed is high, the friction coefficient is low. That is, the μ-ν characteristic of the friction material has a negative gradient, which causes vibration (shudder) due to stick-slip when the clutch is engaged.

  Therefore, in order to remove the high-concentration resin layer on the surface of the friction material and smooth the surface, the outer periphery side of the friction material has been subjected to cutting processing. However, since this cutting processing is usually performed in automatic transmission oil, The oil adheres to the work environment, and the cost is increased.

  Therefore, the friction material is divided into an outer diameter side and an inner diameter side, and the friction material on the outer diameter side is made higher in the blending ratio of the filler than the inner diameter side so that the μ-ν characteristic of the friction material has a positive gradient, that is, the slip rotational speed is The higher the friction coefficient is, the higher the coefficient of friction is, and vibration due to stick-slip is suppressed. The friction material on the inner diameter side increases the fiber ratio to improve flexibility. It was considered to increase the lockup capacity by increasing the coefficient.

  However, as a result of research, it has been clarified that among the fillers, diatomaceous earth is effective in suppressing shudder. Recently, a filler and a friction modifier are combined to form a filler.

  It has also been found that the coefficient of static friction can be made larger than that of the friction material on the outer diameter side by adjusting the filler components including the friction modifier without particularly increasing the fiber component of the friction material on the inner diameter side.

  2 is a front view of the friction material 7 attached to the piston 5 as viewed from the friction surface side, and FIG. 3 is a cross-sectional view in the YY direction of FIG. 71 represents an outer diameter side friction material, 72 represents an inner diameter side friction material, and 73 represents a joint thereof.

  In the lock-up clutch, an outer diameter side friction material that is thicker than the inner diameter side friction material and has a positive slope of μ-ν characteristics first comes into contact with the opposite surface to perform slip control, thereby suppressing the generation of shudder. Therefore, the outer diameter side friction material has a high slip speed and generates large heat due to frictional heat. In recent years, lock-ups have been used at lower speeds, and the thermal load on the friction material used for lock-ups has increased significantly compared to the prior art, and the demand for heat resistance has further increased. Yes.

  In order to solve the above-mentioned problems, the present invention further divides the friction material used for the lock-up clutch and suppresses the generation of the outer-diameter side shudder and attaches them to the clutch piston side and the front cover side, respectively. The lockup clutch characterized by this is obtained.

  The friction material adhered to the clutch piston side has a large heat capacity and a high heat dissipation effect.Although sufficient heat can be released to the front cover side, the friction material on the outer diameter side is further divided in the present invention. Since the heat is also transferred to the clutch piston side, the heat release from both can be combined to reduce the effect of frictional heat on each sliding surface during slip control. I was able to get a clutch.

  The friction material that suppresses the occurrence of the outer diameter side shudder is divided and adhered to the front cover side and the clutch piston side, respectively, but the friction material on the outer peripheral side of the divided friction materials at that time May be attached to the front cover side and the friction material on the inner peripheral side to the clutch piston side, or vice versa.

  Further, since the clutch piston is further reduced in weight due to demands for improving fuel consumption, the rigidity is reduced, and when the clutch is engaged, the central portion of the piston is deformed to the front cover side. Therefore, by making the friction material that suppresses the occurrence of shudder on the outer diameter side thicker than the friction material having a large static friction coefficient on the inner diameter side, the outer diameter side friction material first comes into contact with the opposing surface to control slip. When the fastening is completed, the friction material adheres to the entire surface to increase the torque capacity.

  Furthermore, by providing a seal material between a friction material with a positive gradient μ-ν characteristic on the outer diameter side and a friction material with a large static friction coefficient on the inner diameter side, oil can be supplied to the friction surface to some extent in a sliding state. When the clutch is engaged, it is possible to prevent the oil from flowing into the friction surface of the friction material on the inner diameter side from the high pressure side and to lock up with a large torque capacity.

  4 to 8 are sectional views similar to FIG. 3 showing the embodiments of the present invention. In each figure, 5 is a clutch piston, 21 is a front cover, and 71 is affixed to the outer diameter side. Friction material that performs slip control with a positive gradient in the -ν characteristic, and 72 is a friction material that has a large coefficient of static friction and exhibits a large torque capacity when the clutch is engaged, respectively.

  In the present invention, the outer diameter side friction material 71 that performs slip control is further divided into an outer periphery side friction material 71A and an inner periphery side friction material 71B, which are adhered to the piston 5 or the front cover 21, respectively. Therefore, the large amount of heat generated during slip control at the initial clutch engagement has a large heat capacity and a high heat dissipation effect, and is transmitted to both the front cover side and the piston side in a distributed manner. The heat resistance of 71 is further improved.

  The outer diameter side friction materials 71A and 71B divided into the outer peripheral side and the inner peripheral side, and the inner diameter side friction material 72 having a large static friction coefficient are attached to either the piston 5 or the front cover 21, respectively. is there.

  In the example shown in FIG. 4, the outer diameter side friction material 71A on the outer peripheral side is attached to the piston 5 side, and the outer diameter friction material 71B on the inner periphery side is attached to the front cover 21 side. 72 is attached to the piston 5 side. In the example shown in FIG. 5, the outer diameter side friction materials 71A and 71B are attached at the same position, but the inner diameter friction material 72 is attached to the front cover 21 side.

  In the example shown in FIG. 6, the outer diameter side friction material 71 </ b> A on the outer peripheral side is attached to the front cover 21 side, and the outer diameter side friction material 71 </ b> B on the inner peripheral side is attached to the piston 5 side. Is attached to the piston 5 side. In the example shown in FIG. 7, the inner diameter side friction material 72 is attached to the front cover 21 side, contrary to FIG. 6.

  FIG. 8 shows an embodiment in which the sealing material 8 is provided between the outer peripheral side friction material 71 </ b> B on the inner peripheral side and the inner diameter side friction material 72. In the embodiment shown in FIGS. 4 to 7, the sealing material 8 may be provided on either the piston 5 side or the front cover 21 side, respectively.

  The seal material 8 prevents the friction material 72 on the inner diameter side of the oil from entering the friction surface, and lockup with a high torque capacity is possible.

  Further, in all of the embodiments shown in FIGS. 4 to 8, the outer diameter side friction material 71 is made thicker than the inner diameter side friction material 72, thereby further improving the performance of the lockup clutch as described above. Can be planned.

  Recently, lock-up clutches are becoming smaller and lighter due to demands for improving fuel efficiency. However, according to the present invention, the friction material has high heat resistance during slip control at the initial stage of clutch engagement, and has a large torque capacity when clutch is engaged. A lock-up clutch is obtained.

Sectional drawing which shows the basic composition of the torque converter which has a lockup clutch. Front view of the clutch piston viewed from the friction surface YY sectional view of FIG. Sectional view similar to FIG. 3 showing an embodiment of the present invention Sectional view similar to FIG. 4 showing another embodiment Sectional view similar to FIG. 4 showing still another embodiment Sectional view similar to FIG. 6 showing an embodiment different from FIG. Sectional view similar to FIG. 4 showing an embodiment provided with a sealing material

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Pump part 3 Turbine part 4 Stator 5 Piston 6 Connector 7 Friction material 8 Seal material 10 Torque converter 21 Front cover 22 Outer shell 23 Blade 24 Inner core 32 Outer shell 33 Blade 34 Inner core 35 Turbine hub 51 Damper support part 52 Damper 53 Damper plate portion 54 Damper spring 55 Rivet 56 Turbine hub through hole 71 Outer diameter side friction material 72 Inner diameter side friction material 73 Seam

Claims (3)

The friction material used for the lock-up clutch of the torque converter is divided into an outer diameter side and an inner diameter side, and the outer diameter side friction material has a positive slope of μ-ν, suppressing the occurrence of stickers due to stick-slip, In the lockup clutch configured to increase the torque capacity at the time of clutch engagement, the inner diameter side friction material has a large coefficient of static friction.
A lockup clutch characterized in that the outer diameter friction material for suppressing the generation of the shudder is divided and attached to the piston side and the front cover side, respectively.   2. The lockup clutch according to claim 1, wherein the friction material that suppresses the occurrence of the outer-diameter side shudder is thicker than the friction material having a large static friction coefficient on the inner diameter side.   2. A seal material is provided on the piston side or the front cover side between the friction material for suppressing generation of the outer diameter side shudder and the friction material having a large static friction coefficient on the inner diameter side. The lock-up clutch described.

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