JPS61274125A - Torque transmission device - Google Patents

Abstract

PURPOSE:To prevent a select shock from occurring, by installing an elastic member, having such a load-flectional characteristic as load is once reduced for duration till pressure in a liquid chamber increases from zero and it perfectly reaches to the specified value, interposingly between a piston or a clutch drum and a frictional device. CONSTITUTION:A liquid chamber 24 is partitively formed between a clutch drum 12 and a piston 26, and pressure oil is made feedable through a port 13 in design. A Belleville spring 39 is installed interposingly between a step part 18a of a frictional device 18 and another step part 26. This Belleville spring 39 has such a load-flectional characteristic as load is once reduced for duration till pressure in the oil chamber 24 increases from zero and it perfectly reaches to the specified value. Accordingly, if a friction factor mu grows large, such a range that load in a load-flectional characteristic of the Belleville spring 39 is once reduced is made to correspond to the range whereby these ranges are canceled with each other, thus friction transmission torque is prevented from going too much.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a torque transmission device, for example, a torque transmission device used as a clutch in an automatic transmission of a vehicle.

(Prior Art) Conventionally, such a torque transmission device is disclosed in, for example, Japanese Unexamined Patent Publication No. 17032/1983. This conventional torque transmission device is used in a clutch for an automatic transmission of a vehicle, and when pressure oil is supplied to an oil chamber 24, a piston 26 is transferred to a clutch drum (clutch drum) 12.
The driven plate (first friction member) 14 and the drive plate (second friction member) 22 are compressed by sliding therein. As a result, this clutch 8 is connected and transmits torque, and at this time, the pressing force of the piston 26 is controlled by the dish plate (which is configured to have non-linear load-deflection characteristics with the first and second elastic members 16 and 17). elastic member)
15 is designed to buffer and reduce the shock (select shock) when the clutch is engaged.

(Problems to be Solved by the Invention) However, in such a conventional torque transmission device, the first and second
The elastic members 16 and 17 have a load-deflection characteristic in which the reaction force generated increases as the amount of deformation increases, and the dynamic friction coefficient between the driven plate 14 and the drive plate 22 also increases. The clutch (torque transmission device)
After selecting the shift position of the vehicle to which 8 is to be connected, the frictional transmission torque becomes excessive and a selection shock occurs immediately before complete connection. Furthermore, the torque converter turbine and converter cover, which were rotating in the N range, gradually decelerate, and their rotation stops when the vehicle enters the D range completely. The inertia torque generated at this time is added to the torque from the engine that attempts to rotate the turbine, resulting in an overshoot ΔT in the transmitted torque, as shown in Figure 4(a).
will occur. When the transmitted torque to which this overshoot ΔT is added suddenly decreases, this change in torque is used as an excitation force to generate longitudinal vibration of the vehicle as shown in Figure 4(b), which causes what is called a select shock. There is a problem in that this tendency is exacerbated by the large excessive torque just before the clutch is fully engaged as described above.

(Means for Solving the Problems) Therefore, in order to solve the above problems, the present invention includes a clutch drum, a piston that is slidably housed in the clutch drum and defines a liquid chamber between the clutch drum and the clutch drum. a plurality of first friction members spline-coupled to the clutch drum; and a plurality of first friction members spline-coupled to a rotating member disposed coaxially within the clutch drum and arranged alternately with the first friction members. a plurality of second friction members constituting a friction means, and transmits torque between the clutch drum and the rotating member by supplying pressure fluid to the liquid chamber, wherein the piston or the clutch An elastic member is interposed between the drum and the friction means, and has a load-deflection characteristic such that the load decreases once while the pressure in the liquid chamber increases from zero and reaches a completely constant value. It consists of what was done.

(Function) In the torque transmission device according to the present invention, the first friction member and the second friction member constituting the friction means are friction-pressed by supplying pressure fluid to the liquid chamber.

The clutch drum and a rotating member disposed coaxially inside the clutch drum are connected to transmit torque between them. Also,
By discharging the pressure fluid from the fluid chamber, the friction force between the first friction member and the second friction member is removed, and the clutch drum and the rotating member are separated to cut off torque transmission between them. It has become. At this time, the amount of deflection of the elastic member interposed between the piston or the clutch drum and the friction means gradually changes, so that the friction force also gradually changes, and this causes the first friction member and the second friction member to That is, it is possible to reduce the shock when the clutch drum and the rotating member are connected or disconnected. As shown in FIG. 2, this elastic member has a load-deflection characteristic such that the load decreases once while the pressure in the liquid chamber increases from zero and reaches a completely constant value. . On the other hand, as shown in FIG. 3, the dynamic friction coefficient between the first friction member and the second friction member tends to increase as the relative rotational speed between the friction members approaches zero. There is. For these reasons, even if the dynamic coefficient of friction increases, it is possible to prevent the friction transmission torque from becoming excessive by associating this region with a region where the load in the load-deflection characteristics of the elastic member once decreases. I can do it. As a result, the frictional transmission torque can be kept constant as shown in FIG. 5, and overshoot ΔT as shown in FIG. 4(a) can be prevented from occurring. Therefore, it is possible to prevent longitudinal vibration of the vehicle due to a sudden change in the transmitted torque as shown in FIG. 4(b) described above, thereby preventing an increase in select shock.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing a torque transmission device according to a first embodiment of the present invention applied to an automatic transmission of a vehicle. The same parts as before are given the same reference numerals.

First, the structure will be explained. In FIG. 1, 12 is a clutch drum disposed in a transmission case (not shown), and a piston 26 is slidably housed in the clutch drum 12.

An oil chamber (liquid chamber) 24 is defined between the clutch drum 12 and the piston 26, and pressure oil can be supplied into the oil chamber 24 through the port 13.
The inside of this oil chamber 24 is kept oil-tight by a seal member 23. A spline 1 is installed inside the radius of the clutch drum 12.
2a is formed, and this spline 12a fits into a spline of an input shaft (not shown). Further, a driven plate (first friction member) 14 is spline-coupled to the inner periphery of the clutch drum 12 on the right end side in the figure, and furthermore, a drive plate (second friction member) 22 is connected between each of the driven plates 14. are sandwiched and arranged alternately. Driven plate 14 and drive plate 22 together constitute friction means 18,
A radially inner end of the drive plate 22 is spline-coupled to an internal gear (rotating member), not shown, disposed coaxially within the clutch drum 12.

A cylindrical portion 26a is formed to protrude from the right side of the piston 26 in the figure, and a stepped portion 26b is formed at the tip of the cylindrical portion 26a near the snap ring fitted therein. A stepped portion 18a is formed on the left inner peripheral portion of the friction means 18 in the figure, and a disc spring (elastic member) 39 is interposed between this stepped portion 18a and the stepped portion 26b. The disc spring 39 is
As shown in FIG. 2, it has a load-deflection characteristic in which the load decreases once while the pressure in the oil chamber 24 increases from zero until it reaches a completely constant value. Once this load is reduced, the disc spring 39 is reversely deformed as shown in FIG. 2, but the outer peripheral end and the inner peripheral end of the disc spring 39 are fitted into the stepped portions 18a and 26b, respectively. As a result, the disk spring 39 can be reliably deformed by applying a load both before and after the reversal. A medium-diameter boss portion 12b is formed at a radially intermediate portion of the clutch drum 12, and a spring receiving member 20 is fixed to the right end portion of the boss portion 12b in the drawing. A spring hole 26c is formed radially inward from the cylindrical portion 26a of the piston 26, and two types of return springs 27 and 28 are interposed between the spring hole 26c and the spring receiving member 20. A retainer 2 is provided on the opposite side of the friction means 18 from the piston 26.
9 is fixed, and this retainer 29 is connected to the friction means 1.
When the pressure of the oil chamber 24 is applied to the left end side in the figure of 8 through the piston 26, it has an action to counteract the pressure.

Next, the effect will be explained. The case of selecting the shift position of the automatic transmission from the N range to the D range will be explained. When a manual valve (not shown) is selected from the N range to the D range, pressure oil is supplied from the port 13 to the oil chamber 24, and the piston 26 moves to the return spring 27.
The friction means 1 moves to the right in the figure against the biasing force of the piston 28, and the friction means 1
Pressure is transmitted to 8.

The driven plate 14 and the drive plate 22 are friction-bonded. In this way, the clutch drum 12 and an internal gear (not shown) are connected to transmit torque therebetween. At this time, a disc spring 39 interposed between the recess 26b of the piston 26 and the recess 18a of the friction means 18
As the amount of deflection gradually changes, the frictional force, that is, the frictional transmission torque also gradually changes. Shock when connecting or disconnecting can be reduced.

Modeling the excitation force generation mechanism of the aforementioned select shock as shown in Fig. 7, and assuming that the torque input from the engine E to the turbine TU of the torque converter is as shown in Fig. 8, the friction generated in the clutch C is calculated as follows. The following equation is obtained by calculating the function of the rotational speed of the turbine TU, etc. with respect to time such that the torque (input torque to the vehicle) does not cause the above-mentioned overshoot and becomes as shown in FIG.

bo −□(t−τ)U(−τ) τ ・・・・・・■ This equation 0 is illustrated in FIG. 6. Comparing FIG. 5 and FIG. 6, it can be seen that after 1 hour τ, the transmitted torque T is constant and the rotational speed δ of the turbine etc. decreases. Here, the friction transmission torque T is given by the friction coefficient x the friction material pressing force x the average diameter of the friction material.

As shown in Fig. 3, the coefficient of friction generally decreases as the relative rotational speed V of the friction members approaches zero.
are in an increasing relationship. In order to keep the friction transmission torque T constant while decreasing the relative rotational speed, it is necessary to reduce the friction material pressing force, that is, the fastening force of the friction means 18 of the torque transmission device. Further, in the torque transmission device according to the first embodiment, while the amount of deflection increases between the piston 26 and the friction means 18 as shown in FIG. 2, that is, the pressure in the oil chamber 24 increases from zero. A disc spring 39 is provided which has a load-deflection characteristic such that the load decreases once until it reaches a completely constant value. From these facts, even if the dynamic friction coefficient μ increases, it is mutually canceled by making the region correspond to the region where the load in the load-deflection characteristics of the disc spring 39 once decreases,
By preventing the friction transmission torque T from becoming excessive as a whole, it is possible to keep it constant. Therefore, when selecting the shift position of the vehicle to which the torque transmission device is connected,
It is possible to effectively prevent a phenomenon in which the frictional transmission torque of the torque transmission device becomes excessive and a so-called select shock occurs.

FIG. 9 shows a second embodiment of the present invention. In the first embodiment, the disc spring 39 connects the piston 26 with the friction means 1.
8, whereas the second embodiment differs in that the disc spring 41 is interposed between the clutch drum 12 and the friction means 18. That is, a recess 12c is formed by a snap ring 43 at the right end of the clutch drum 12 in the drawing.
Furthermore, a recess 40a is formed on the right side of the retainer 40 disposed at the right end in the figure of the friction means 18, and a disc spring 41 is interposed between these recesses 12C and 40a.

When pressure oil is supplied from the boat 13 to the oil chamber 24, the piston 26 moves to the right in the figure against the biasing force of the return springs 27, 28, and the pressure is transmitted to the friction means 18, causing the driven plate 14 to move. and the drive plate 22 are friction-bonded. At this time, the recess 4 of the retainer 40 that comes into contact with the recess 12c of the clutch drum 12 and the friction means 18
By gradually changing the amount of deflection of the disc spring 4■ interposed between the drive plate 14 and the drive plate 22, the drive plate 14 and the drive plate 22, that is, the clutch drum 12 (not shown) Smooth connection with internal gear. Since the disc spring 41 in this second embodiment also has the same load-deflection characteristics as the disc spring 39 in the first embodiment, the same effect as in the previous first embodiment can be obtained, and the arrangement of the disc spring The degree of freedom can be increased.

In addition, in the first and second embodiments, the disc spring 39
Alternatively, friction means 1 can be applied only by the load-deflection characteristics of 41
8 has been described in which the frictional engagement force is reduced, but since the rate of change of the frictional engagement force can change depending on the amount of oil flowing into the oil chamber 24, it is possible to reduce the frictional engagement force in the two regions regardless of the oil temperature. In order to always perform the above-mentioned cancellation, the boat 13 may be provided with an orifice whose diameter is changed over depending on the oil temperature. Similarly, since 00 (idling rotation) in FIG. 6 is high while the engine is warming up, the orifice may be switched depending on the engine rotation speed.

(Effects of the Invention) As explained above, according to the present invention, a load is applied between the piston or the clutch drum and the friction means while the pressure in the liquid chamber increases from zero until it reaches a completely constant value. By interposing the elastic member which has a load-deflection characteristic such that .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the torque transmission device according to the first embodiment of the present invention, FIG. 2 is a load-deflection characteristic diagram of the disc spring 39 in FIG. 1, and FIG. 3 is a driven plate 1 in FIG. 1.
4 (a) is a graph showing the relationship between the dynamic friction coefficient μ between the drive plate 22 and the relative rotational speed V between them, and FIG. A graph showing the relationship between the transmission torque transmitted to the input shaft via the input shaft and time, Figure 4 (b) shows the vehicle longitudinal vibration (select shock) corresponding to the fluctuation of the transmission torque shown in Figure 4 (a). FIG. 5 is a graph showing the relationship between time and torque transmitted from the engine to the transmission output shaft via the torque converter and friction means 18 during selection in an automatic transmission using the torque transmission device according to the present invention and time. 6 is a graph showing the relationship between the rotational speed of the turbine of the torque converter, etc. and time, and FIG. 7 is a model showing the torque transmission relationship between engine E, clutch C, and turbine TU. 8 is a graph showing the relationship between the torque transmitted from the engine and the rotational speed of a turbine, etc., and FIG. 9 is a sectional view showing a torque transmission device according to a second embodiment of the present invention. 12...Clutch drum, 12a...Spline, 12b...Medium diameter boss portion, 12c...Recessed portion, 13...Port, 14・・・・・・Driven plate (first friction member),
18...Friction means. 18a...Step part, 20...Spring receiving member, 22...Drive plate (second friction member),
23... Seal member, 24... Oil chamber (liquid chamber), 2G... Piston, 26a... Cylindrical portion. 26b...Step part, 26c...Spring hole, 27.28...Return spring, 29.4
0...Retainer, 39.41...Disc spring, 40a...Recess, 43...Snap ring, E...Engine, TU ...Turbine, C...Clutch, IS...Input shaft.

Claims (1)

[Claims] a clutch drum, a piston that is slidably housed in the clutch drum and defines a fluid chamber between the clutch drum, a plurality of first friction members spline-coupled to the clutch drum, and a piston that is slidably housed in the clutch drum and defines a fluid chamber between the clutch drum and the clutch drum; a plurality of second friction members spline-coupled to a rotating member arranged coaxially, arranged alternately with the first friction members and constituting a friction means together with the first friction members; In a torque transmission device that transmits torque between the clutch drum and a rotating member by supplying
Between the piston or clutch drum and the friction means, there is an elastic material having a load-deflection characteristic such that the load decreases once while the pressure in the liquid chamber increases from zero and reaches a completely constant value. A torque transmission device characterized by interposing a member.