JP2001165196A - Cooling mechanism for wet clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cooling mechanism for a wet clutch capable of performing efficient cooling. SOLUTION: A first oil path 30 is formed in a clutch piston 28. A diametric spread part is formed in this oil path 30, a spherical unit 42 is received in this diametric spread part. One end of a coil spring 44 is fixed to the spherical unit 42. The spherical unit 42, energized by the coil spring 44, closes the oil path 30. When lubricating oil L is infiltrated in a first clutch oil chamber 34, the clutch piston 28 is moved, a clutch plate 20 and a friction plate 22 are engaged. When a pressure of oil in the clutch oil chamber 34 leads to a preset value, the spherical unit 42 is moved to the center of the diametric spread part against elastic force of the coil spring 44, to open the oil path 30. Consequently, when a large heating value is generated by engagement, the lubricating oil L can be supplied to the clutch plate 20 and the friction plate 22 through the oil path 30, so that efficient cooling can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet clutch used for an automatic transmission of an automobile and the like, and more particularly, to a wet clutch cooling mechanism for supplying lubricating oil to a friction plate of the clutch.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 4, in a multi-plate clutch 100 used for an automatic transmission for an automobile or the like,
A plurality of clutch plates 102 and a plurality of friction plates 104 are arranged alternately.

[0003] Here, the clutch plate 102 and the friction plate 104 are connected to each other by the lubricating oil Q flowing into the clutch oil chamber 106 from an oil passage (not shown).
08, and the clutch piston 108 is engaged by pressing the clutch plate 102. Since heat is generated at the time of such engagement, a constant lubricating oil Q is always supplied from a lubrication hole 114 provided in the shaft 112,
Clutch plate 102 and friction plate 10
4 was allowed to cool. At the same time, the lubricating oil Q causes the clutch plate 102 and the friction plate 1
This prevents deterioration due to friction and wear during engagement with the C.04.

[0004]

However, not only when the clutch plate and the friction plate are engaged, but also during idle running (when disengaged) where there is no need to supply the lubricating oil, a constant amount of lubricating oil is constantly supplied. Since it was supplied, efficient cooling was not possible.

In addition, there is a limit to the amount of lubricating oil supplied from the lubricating holes, and the amount of heat generated by the increase in the friction coefficient of the clutch plate and the friction plate corresponding to the recent high efficiency of automatic transmissions is not sufficient. Could not respond to.

[0006] The above is particularly problematic in the present situation where it is difficult to calculate the actual amount of lubricating oil supply because the oil pressure in the shaft is unclear.

In view of the above, an object of the present invention is to provide a cooling mechanism for a wet clutch which can perform efficient cooling.

[0008]

According to a first aspect of the present invention, there is provided a cooling mechanism for a wet clutch, comprising: a clutch plate which rotates together with an input member; a friction plate which engages with the clutch plate and transmits a rotational force to an output member; A pressing member that engages the clutch plate and the friction plate with the oil pressure of the lubricating oil in the oil chamber formed between the members,
An oil passage formed in the pressing member and configured to supply lubricating oil in the oil chamber to the clutch plate and the friction plate is opened when the oil pressure in the oil chamber reaches the first set value after the clutch plate and the friction plate are engaged. A valve to
It is characterized by having.

With this configuration, the pressing member is pressed by the oil pressure of the lubricating oil in the oil chamber, and the clutch plate and the friction plate are engaged. Then, when the oil pressure in the oil chamber reaches the first set value, a valve provided in the oil passage opens, and lubricating oil is supplied to the clutch plate and the friction plate. Therefore, lubricating oil is supplied when the clutch plate and the friction plate are engaged and generating heat, so that the clutch plate and the friction plate can be efficiently cooled.

On the other hand, since the valve is closed until the clutch plate and the friction plate are engaged, the oil pressure in the oil chamber quickly rises. For this reason, the pressing member reacts quickly, and the engagement between the clutch plate and the friction plate can be quickly performed. That is, the responsiveness of the wet clutch can be improved.

In this case, it is preferable that after the valve is opened, when the oil pressure in the oil chamber further increases and reaches the second set value, the valve is closed.

According to this configuration, when the oil pressure in the oil chamber reaches the first set value, the valve is opened and lubricating oil is supplied to the clutch plate and the friction plate. When the set value of 2 is reached, the valve closes. Therefore, lubricating oil can be supplied when the clutch plate and the friction plate are engaged,
After the engagement that does not require cooling, the supply of the lubricating oil can be stopped.

Further, since the valve is closed, the oil pressure in the oil chamber can be secured, and the pressing force of the pressing member acting on the clutch plate and the friction plate after engagement can be sufficiently ensured. Therefore, the engagement pressure between the clutch plate and the friction plate can be secured.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a cooling mechanism for a wet clutch according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a partial sectional view of an automatic transmission employing a cooling mechanism for a wet clutch used in the present invention.

The automatic transmission 10 shown in FIG.
And the output shaft 14 in a concentric positional relationship. Input shaft 1
A wet clutch 16 is disposed radially outward of the second clutch 2. The wet clutch 16 includes an input member 18,
The inner periphery of the input member 18 is fixed to the outer periphery of the input shaft 12 via a spline (not shown). Input member 1
A plurality of clutch plates 20 are disposed radially inward of the cylindrical portion 18A. This clutch plate 2
A claw (not shown) provided on the outer periphery of No. 0 is engaged with a groove (not shown) formed on the inner periphery of the cylindrical portion 18A.

A plurality of friction plates 22 are arranged between the clutch plates 20. A claw (not shown) is formed on the inner periphery of the friction plate 22, and the claw is engaged with the spline 24. An output member 26 is located inside the spline 24, and a power transmission portion 26A
Is formed, and the power transmission portion 26A is connected to the output shaft 14
Is engaged. A supply hole 32 for supplying the lubricating oil Q to the clutch plate 20 and the friction plate 22 is formed in a part of the output member 26.

A clutch piston 28 is slidably disposed inside the input member 18 with a seal member 29 interposed therebetween. The clutch piston 28 includes a pressing portion 28A that presses the clutch plate 20. Also,
The space formed by the clutch piston 28 and the input member 18 is provided in a first clutch oil chamber 34 into which the lubricating oil L enters.
It has become. In a space 36 formed by the clutch piston 28 and the output member 26, substantially atmospheric pressure air is present, and oil droplets of the lubricating oil Q are mixed. Next, the configuration of the oil passage formed in the clutch piston will be described. As shown in FIG. 1, lubricating oil L
The clutch plate 20 and the friction plate 22
A first oil passage 30 having a circular cross-section to be supplied to the first oil passage is formed.

As shown in FIG. 2, the first oil passage 30
Has an inlet portion 30A having a relatively small diameter. Further, an enlarged diameter portion 30B having a diameter larger than the diameter of the inlet portion 30A communicates with the inlet portion 30A. In addition, an outlet portion 30C formed to have the same diameter as the inlet portion 30A communicates with the enlarged diameter portion 30B. The outlet portion 30C has a reduced diameter portion 30D having a smaller diameter than the outlet portion 30C.
Are in communication. The reduced diameter portion 30D communicates with an end surface 28B of the pressing portion 28A of the clutch piston 28 located on the clutch plate 20 side.

More specifically, a first inclined surface 38 is formed on the enlarged diameter portion 30B, and the enlarged diameter portion 30B is connected to the inlet portion 30A via the first inclined surface 38. . Further, a second inclined surface 40 is formed in the enlarged diameter portion 30B, and the enlarged diameter portion 30B is connected to the outlet portion 30C by the second inclined surface 40.

A sphere 42 is housed in the enlarged diameter portion 30B. The diameter of the spherical body 42 is set to be larger than the diameter of the inlet 30A, while being smaller than the diameter of the enlarged diameter part 30B.

One end of a coil spring 44 is fixed to the sphere 42. The other end of the coil spring 44 is fixed to the end face 31 of the outlet 30C. Therefore, in normal times, the sphere 42 is urged by the elastic force of the coil spring 44 and comes into contact with the first inclined surface 38 of the enlarged diameter portion 30B,
Communication between the inlet portion 30A and the enlarged diameter portion 30B is prevented.

When the oil pressure in the first clutch oil chamber 36 reaches a predetermined value (first set value H1), the coil spring 44 contracts due to the ball 42 being pushed by the oil pressure of the lubricating oil L.
The sphere 42 is separated from the first inclined surface 38, and the entrance 30A and the enlarged diameter portion 30B communicate with each other. Further, the oil pressure inside the first clutch oil chamber 36 is set to a predetermined value (second set value H
When 2) is reached, the coil spring 44 contracts further and the sphere 42
Comes into contact with the second inclined surface 40 of the enlarged diameter portion 30B and the enlarged diameter portion 30
In this configuration, communication between B and the outlet portion 30C is prevented.

As described above, the enlarged diameter portion 30B forms a valve by the sphere 42 and the coil spring 44.

Next, the operation and effect of the cooling mechanism of the wet clutch will be described with reference to FIGS.

First, the initial stage of engagement between the clutch plate 20 and the friction plate 22 (hereinafter referred to as "initial engagement" as appropriate) will be described.

The lubricating oil L is controlled by an external hydraulic control circuit (not shown), passes through a second oil passage (not shown),
Are stored in the clutch oil chamber 34. Here, the oil pressure in the first clutch oil chamber 34 rises according to a command of the oil pressure control circuit, and the clutch piston 28 is pushed out. That is, the clutch piston 28 is pressed by the lubricating oil L and moves in the direction of the arrow A in the drawing, comes into contact with the clutch plate 20 and presses the clutch plate 20. When the clutch plate 20 is pressed, the clutch plate 20 and the friction plate 22 come into contact. That is, the engagement of the wet clutch 16 is started.

At this stage, as shown in FIG.
The lubricating oil L penetrates into the inlet 30A of the first oil passage 30 and presses the sphere 42.
4, the ball 42 does not move. For this reason,
The pressure inside the first clutch oil chamber 34 can quickly rise, and accordingly, the time until the clutch plate 20 and the friction plate 22 are engaged can be shortened, and the responsiveness of the wet clutch 16 can be ensured. .

In the initial stage of engagement, as in the prior art,
A minimum necessary amount of lubricating oil Q is also supplied to the clutch plate 20 and the friction plate 22 from the supply hole 32.

Next, the middle stage of engagement between the clutch plate 20 and the friction plate 22 (hereinafter referred to as "middle period of engagement" as appropriate) will be described.

Further, when the lubricating oil L enters the first clutch oil chamber 34 from the second oil path, the pressure of the first clutch oil chamber 34 increases. Thus, the pressing force of the clutch piston 28 pressing the clutch plate 20 further increases, and the engagement pressure between the clutch plate 20 and the friction plate 22 increases.

Here, when the oil pressure inside the first clutch oil chamber 34 reaches a predetermined value H1 (first set value), the lubricating oil L
Hydraulic pressure exceeds the elastic force of the coil spring 44,
Moves in the direction of arrow B in FIG. At this time, FIG.
As shown in FIG. 5, the spherical body 42 is stationary at substantially the center of the enlarged diameter portion 30B due to the balance between the oil pressure of the lubricating oil L and the elastic force of the coil spring 44.

When the sphere 42 moves to substantially the center of the enlarged diameter portion 30B, the inlet portion 30A of the first oil passage 30 communicates with the enlarged diameter portion 30B, and the lubricating oil L flows from the inlet portion 30A to the enlarged diameter portion 30B. Penetrate. The lubricating oil L that has entered the enlarged diameter portion 30B further enters the outlet portion 30C and the reduced diameter portion 30D. Then, the lubricating oil L is supplied to the clutch plate 20 and the friction plate 22 from the reduced diameter portion 30D. By supplying the lubricating oil L, it is possible to cool the clutch plate 20 and the friction plate 22 which have generated heat due to the engagement, and it is possible to prevent wear due to engagement and deterioration due to friction.

As described above, the lubricating oil L is supplied from the first oil passage 30 formed in the clutch piston 28 to the vicinity of the clutch plate 20 and the friction plate 22, so that the cooling can be efficiently performed. Also,
In the middle period of engagement where the heat generation is the largest, a large amount of lubricating oil L is supplied to the clutch plate 20 and the friction plate 22 with an increase in the oil pressure of the first clutch oil chamber 34, so that the cooling capacity can be increased.

In the middle stage of engagement, as in the prior art,
A minimum necessary amount of lubricating oil Q is also supplied to the clutch plate 20 and the friction plate 22 from the supply hole 32.

Next, the later stage of engagement between the clutch plate 20 and the friction plate 22 (hereinafter referred to as "late engagement" as appropriate) will be described. In this late stage of engagement, the clutch plate 20 and the friction plate 22 are completely engaged, and the rotational force of the input shaft 12 is
4 is transmitted.

Further, when the lubricating oil L enters the first clutch oil chamber 34 from the second oil passage, the first clutch oil chamber 3
4 The oil pressure inside increases. Here, as shown in FIG. 2 (C), when the oil pressure inside the first clutch oil chamber 34 reaches a predetermined value (second set value H2), the sphere 42 is pushed, and the first expanded portion 30B of the enlarged diameter portion 30B is pushed. 2 and the communication between the enlarged diameter portion 30B and the outlet portion 30C is prevented. That is, the lubricating oil L cannot enter the outlet portion 30C from the enlarged diameter portion 30B.

Thus, after the engagement that does not require cooling, the supply of the lubricating oil L to the clutch plate 20 and the friction plate 22 can be stopped. Further, the oil pressure of the lubricating oil L (the oil pressure inside the first clutch oil chamber 34) that presses the clutch piston 28 can be secured, and the pressing force of the clutch piston 28 acting on the clutch plate 20 and the friction plate 22 after engagement is reduced. We can secure enough. As a result, the engagement pressure between the clutch plate 20 and the friction plate 22 can be secured. Further, the torque capacity after engagement is not impaired. The relationship between the time and the pressure in the initial, middle and late stages of engagement between the clutch plate 20 and the friction plate 22 described above will be described with reference to FIG.

The curve A in FIG.
6 is a curve showing a difference between the rotation speeds of the friction plate 22 and the friction plate 22. The curve A shows the maximum value (constant value) since the clutch plate 20 is rotating and the friction plate 22 is not rotating until the initial stage of engagement between the clutch plate 20 and the friction plate 22 (point G in the figure). It has become. Then, from the initial stage of the engagement, the curve A decreases rightward, and sharply decreases from the middle stage of the engagement (point H in the drawing). This indicates that the difference between the rotational speeds of the clutch plate 20 and the friction plate 22 has disappeared due to the engagement. Furthermore, since the clutch is completely engaged in the latter half of the engagement (point I in the drawing), the difference in the rotational speed between the clutch plate 20 and the friction plate 22 is completely eliminated, and the rotational speed becomes the same.

The curve B represents the first clutch oil chamber 34.
It is a curve showing the internal pressure (oil pressure of lubricating oil L). In the early stage of engagement, the lubricating oil L starts to enter the first clutch oil chamber 34, and the oil pressure in the first clutch oil chamber 34 rises rapidly. In the middle period of engagement, the first clutch oil chamber 3
The valve is opened while the pressure inside 4 reaches the first set value H1 and the hydraulic pressure continues to rise slightly. Further, in the latter half of the engagement, the oil pressure in the first clutch oil chamber 34 reaches the second set value H2, and after the valve is closed, the oil pressure in the first clutch oil chamber 34 sharply increases.

A curve C represents a heat generation amount (rotational speed difference *) due to engagement between the clutch plate 20 and the friction plate 22.
(Proportional to the value of the pressure inside the clutch oil chamber). As shown in FIG. 3, it can be seen that the calorific value is the largest during the middle period of engagement, and is substantially zero in the latter period of engagement.

The curve D is a curve representing the flow rate of the lubricating oil L flowing through the first oil passage 30. As shown in FIG. 3, in the middle period of the engagement, the pressure inside the first clutch oil chamber 34 becomes the first pressure.
When the set value H1 is reached, the valve is opened, so that the lubricating oil L flows through the first oil passage 30. 1st in late engagement
When the pressure inside the clutch oil chamber 34 reaches the second set value H2, the valve is closed again, so that the lubricating oil L flowing through the first oil passage 30 decreases rapidly, and finally the flow rate of the lubricating oil L Becomes zero.

As described above, the wet clutch 16 of the present invention is
According to the cooling mechanism of (1), a large amount of the lubricating oil L is supplied to the clutch plate 20 and the friction plate 22 from the middle stage to the late stage of engagement between the clutch plate 20 and the friction plate 22 that generate the largest amount of heat.
It can be cooled efficiently.

Further, since the valve is closed in the latter half of the engagement when cooling is not necessary, the pressure inside the first clutch oil chamber 34 can be secured, and the engagement pressure between the clutch plate 20 and the friction plate 22 can be secured. .

[0044]

According to the cooling mechanism of the wet clutch of the present invention, the input side friction plate and the output side friction plate can be efficiently cooled.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an automatic transmission including a cooling mechanism for a wet clutch according to an embodiment of the present invention.

FIG. 2 is an operation diagram showing an opening and closing operation of a valve constituting a cooling mechanism of a wet clutch according to one embodiment of the present invention.

FIG. 3 is a diagram showing transition of each variable when the wet clutch according to the embodiment of the present invention is engaged.

FIG. 4 is a partial cross-sectional view of an automatic transmission including a cooling mechanism for a wet clutch according to the related art.

[Explanation of symbols]

 Reference Signs List 16 wet clutch 18 input member 20 clutch plate 22 friction plate 26 output member 28 clutch piston (pressing member) 30 first oil passage (oil passage) 34 first clutch oil chamber (oil chamber) 42 sphere (valve) 44 coil Spring (valve)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanori Iriya 41-cho, Chuchu-Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Institute, Inc. (72) Inventor Hisashi Watanabe, Nagakute-machi, Aichi-gun, Aichi Prefecture 41, Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Masataka Osawa 41, Toyoda Central R & D Laboratories Co., Ltd. 1 Toyota Town Toyota City Toyota Motor Corporation (72) Inventor Hiroaki Takeuchi 1 Toyota Town Toyota City Aichi Prefecture Toyota Motor Corporation F term (reference) 3J057 AA04 BB04 CA03 DA03 GA71 GD14 HH02 JJ04

Claims (2)

[Claims] A clutch plate that rotates together with an input member, a friction plate that engages with the clutch plate and transmits a rotational force to an output member, and a lubricating oil in an oil chamber formed between the input member and the friction member. A pressing member that engages the clutch plate and the friction plate with hydraulic pressure; and an oil passage formed in the pressing member and configured to supply lubricating oil in the oil chamber to the clutch plate and the friction plate. And a valve that opens when the oil pressure in the oil chamber reaches a first set value after the friction plate has been engaged, and a cooling mechanism for a wet clutch. 2. The cooling mechanism for a wet clutch according to claim 1, wherein the valve is closed when the oil pressure in the oil chamber further increases and reaches a second set value after being opened.