JPH0366967A - Slip control device in fluid start-up device - Google Patents

Abstract

PURPOSE:To moderate vibration and shock by disposing a slip clutch at a lock-up clutch in series and providing a cam mechanism,for generating tension corresponding to load torque, at the output side power transmission path of a fluid coupling. CONSTITUTION:A slip clutch 5 is series-disposed at a lock-up clutch 3 for connecting the output side 21 of a fluid coupling 2 directly to the input side 22, so that large load torque is absorbed by the slip of the clutch 5. A cam mechanism 6 for generating tension corresponding to the load torque is disposed at a power transmission path in the output side 21. When the clutch 5 slips, the fluid coupling 2 is relatively rotated on the input-output sides to perform transmission through a turbine runner 21a, the cam mechanism 6 and a hub part 21b. In this case, tension corresponding to the load torque is generated at the cam mechanism by the relative rotation, and the slip clutch 5 enlarges torque capacity correspondingly, thus improving drivability.

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a starting device in an automatic transmission for a vehicle,
It is particularly suitable for use in vehicular automatic transmissions incorporating a belt-type continuously variable transmission, and more specifically, in a starting device having a fluid coupling (including a torque converter), a lock-up clutch, and a slip clutch. This invention relates to the structure of a cam mechanism that applies an axial force corresponding to the load torque.

(B) Conventional technology Conventionally, automatic transmissions incorporating a belt-type continuously variable transmission (CVT) have been known as automatic transmissions incorporating torque converters, fluid couplings, etc. A device equipped with a starting device consisting of a joint and a centrifugal lock-up clutch has been devised.

Generally, centrifugal friction clutches, which are used as lock-up clutches in fluid couplings, have a weight supported by pins at both ends, and apply a biasing force to the weight in the direction of resisting centrifugal force, or apply force to the tractor spring or coupling case. It consists of a shoe that can make contact and a main spring interposed between the shoe and the retractor spring, and has characteristics as shown in FIG.

That is, when the output side rotation of the fluid coupling is below a predetermined rotational speed, the shoe has a gap with the case due to the retractor spring, and the clutch is in the disengaged state (non-operating region A). The torque from the engine is transmitted to the automatic transmission body via a fluid coupling, allowing the vehicle to start smoothly. Then, when the output side rotational speed reaches a predetermined speed or higher, the weight pushes the retractor spring due to centrifugal force, contacts the shoe case, and starts torque transmission (constant speed region B). In the constant speed range B, the centrifugal force acting on the weight presses the weight in a shoe-like manner, and the centrifugal force acting on the shoe itself is also applied, so the torque capacity increase rate of the clutch is large, and the torque capacity increases when driving at low speeds. The aim is to improve fuel efficiency. Furthermore, when the output side rotation speed increases, the weight comes into contact with the pin, and the centrifugal force acting on the weight does not act on the shoe, and torque is transmitted based on the centrifugal force acting on the shoe itself (in the medium speed range). C).

In the medium speed range C, the rate of increase in torque capacity is relatively low, and torque vibration and shift shock caused by knocking etc. are absorbed by clutch slippage (torque limiter function).
Then, when the output side rotation speed further increases, the main spring is deflected outward due to centrifugal force, the centrifugal force of the main spring itself is added, and the lock-up torque curve also becomes upward (high speed range D). Note that E in the figure indicates the maximum torque of the engine.

Generally, in a torque converter (hydraulic coupling) used in a vehicle automatic transmission, a lock-up clutch is connected to the turbine runner hub, and by switching the oil path or hydraulic actuator that supplies oil to the converter,
Hydraulic lock-up clutch devices that control the lock-up clutch to bring it into frictional contact with a front cover or to release it are well known.

(c) Problems to be Solved by the Invention By the way, even with the above-mentioned centrifugal lock-up clutch having the dribble function, the output side rotational speed increases when a high load is applied, for example during kickdown. In this case, due to the increase in clutch capacity and high load associated with the increase in rotation, clutch stick slip appears strongly,
This hinders smooth kickdown acceleration, and particularly in the high speed range and medium speed range C near the high speed range, the clutch capacity is too large, causing shift shock.

In addition, if the torque capacity of the clutch is set to a small value, the lock-up clutch will often slip even during steady driving on a flat road, which will reduce fuel consumption, especially in the constant speed range B and the medium speed range C) on the constant speed side. Resulting in.

The problems of stick-slip and clutch slip mentioned above occur particularly in the centrifugal lock-up clutch, but they also occur in the above-mentioned hydraulic lock-up clutch.

Therefore, the present applicant installed a slip clutch in series with a lock-up clutch, for example, a centrifugal lock-up clutch, and also installed a slip clutch in the power transmission path on the output side of the fluid coupling.
A cam mechanism is provided that generates an axial force corresponding to the load torque, and the cam mechanism acts on the axial force on the slip clutch to reduce the torque capacity of the slip clutch interposed in the power transmission system from the lock-up clutch to the load torque. proposed a fluid starting device configured to cope with this problem, thereby reducing the occurrence of the above-mentioned shift shock and reduction in fuel efficiency (Japanese Patent Application No. 70158/1983; unpublished at the time of filing of this application).

By the way, in the fluid starting device, the end face angle of the end face cam constituting the cam mechanism is set constant over the entire stroke.

Therefore, the change in the axial force generated by the cam mechanism is always constant regardless of the magnitude of the input torque.For example, if the end face angle of the end face cam is set small in order to reduce the slip ratio of the fluid starting device, When the input torque to the cam mechanism is large, such as during a stall, the axial force generated by the cam mechanism becomes excessive, causing the friction material of the slip clutch, the disc spring that applies a predetermined pressing force to the friction material, and the disc. The issue is the rigidity of the snap ring that locks the spring to prevent it from slipping out, or the cam mechanism itself. Conversely, if the end face angle of the end cam is set large,
Even if the problem with the rigidity of the above-mentioned components is solved, if the input torque to the cam mechanism is small (during slip control),
The axial force generated by the cam mechanism is small, and the slip ratio cannot be sufficiently reduced, making it impossible to sufficiently improve fuel efficiency. In particular, when using an improved centrifugal lock-up clutch that engages from relatively low rotations, the slip rate can be sufficiently reduced from a relatively low rotation state at the time of starting, corresponding to the characteristics of the lock-up clutch. I can't.

SUMMARY OF THE INVENTION Therefore, the present invention provides a fluid starting device in which the cam surface of the cam mechanism is changed in accordance with its stroke position, thereby solving the above-mentioned problems regarding the rigidity of the components and improving the fuel efficiency of the vehicle. The purpose is to

(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned circumstances, and for example, as shown with reference to FIGS.
and the output (III (21)) and input side (2
In a fluid starting device (1) comprising a lock-up clutch (3) (for example, a centrifugal lock-up clutch) directly connected to the lock-up clutch (3), a slip clutch (5) is disposed in series with the lock-up clutch (3). In addition, a cam mechanism (6) that generates an axial force corresponding to the load torque is disposed on the power transmission path on the output side (21) of the fluid coupling, and the axial force generated by the cam mechanism is transferred to the slip clutch (21). 5
), and the cam surface (61) of said cam mechanism, (
62), a portion (61a) that functions when the torque input to the cam mechanism is small, a portion (62a) that generates a relatively high axial force, and a portion (61b) that functions when the input torque is large, ( 62b) is characterized by having a shape that generates relatively low axial force.

(E) Function Based on the above configuration, when the vehicle is started, the lock-up clutch (3) is in the disengaged state, and torque from the engine is exclusively transmitted to the automatic transmission via the fluid coupling (2), and the fluid It starts smoothly based on the oil flow of the joint. When the lock-up clutch is a centrifugal lock-up clutch, when the rotational speed of the output side (21) of the fluid coupling (2) reaches a predetermined speed, the lock-up clutch (3) starts transmitting torque. The torque capacity of the clutch (3) increases rapidly due to centrifugal force. In addition, a lock-up clutch (
3) is in the connected state, if a large load is applied to the output side (21) when starting, or due to kickdown, sudden braking, upshifting, etc., or if vibration occurs on the input side due to knocking, etc., the slip clutch (5) slips, and the above-mentioned load or vibration is smoothly absorbed. On this occasion,
When the slip clutch (5) slips, the fluid coupling (
2) rotates relative to the input side (22) and output side (21) of the turbine runner (21a) through the fluid coupling.
), the power is transmitted to the cam mechanism (6), the wing part (2l b), and the automatic transmission body, but the cam mechanism (6) interposed in the power transmission path responds to the load torque based on relative rotation. This generates an axial force, which acts on the slip clutch (5), and the slip clutch (5) increases its torque capacity in response to the increase in load torque. Therefore, for example, during kickdown, the load torque once becomes zero and then suddenly rises, but at this rise, the slip clutch (5) slips, and the power is first transmitted via the fluid coupling (2). As a result, the torque capacity of the slip clutch (5) increases in response to the load torque, and power is transmitted while reducing or eliminating slippage of the slip clutch (5).

When the input torque transmitted from the turbine launch (21a) of the fluid coupling (2) to the cam mechanism (6>) is small, such as when starting, for example, as shown in FIG. 2(a),
The roller (63) of the cam mechanism (6) has a cam surface (61), (
62), where the end face angle (θ, ) of the cam surface is small, that is, the portions (61a) and (62a) where high axial force is generated on the cam surface, and corresponds to the load torque. generates a relatively large axial force, thereby increasing the torque capacity of the slip clutch (5) at a relatively high rate (for example, see section 81 in Figure 3), and increasing the slip rate of the slip clutch (5). reduce

Furthermore, when the input torque transmitted to the cam mechanism (6) is large, such as when stalling, for example, as shown in FIG. 2(b), the roller (63) of the cam mechanism (6)
1) and (62), the end face angle (θ
2), that is, the parts (61b) and (62b) where low axial force is generated on the cam surface, generate a relatively small axial force with respect to the load torque, thereby causing the slip clutch (5> (See, for example, section 82 in FIG. 3) at a relatively low rate.

(f) As described in detail, according to the present invention, the slip clutch (5) is disposed in series with the lock-up clutch (3), so that when starting the vehicle, the slip clutch (5) is smoothly connected via the fluid coupling (2). Even when the lock-up clutch (3) is engaged, if a larger load torque is applied during start-up, kickdown, engine knocking, upshifts, etc., the slip clutch (5) slips and the load is Torque is absorbed, vibration and shock are reduced, and drivability is improved.Furthermore, a cam mechanism (6) is installed that generates axial force corresponding to the load torque, and the slip clutch (5) handles the load torque. Since it has a torque capacity corresponding to the load torque, the torque capacity of the slip clutch (5) can be automatically controlled in accordance with the load torque with an extremely simple configuration that does not require a complicated electric or hydraulic mechanism.
In the event of sudden torque fluctuations, the fluid coupling (2
) to absorb large load torque, and then immediately increase the torque capacity of the slip clutch (5) to increase the transmission torque of the direct coupling system, thereby reducing control delays etc. in any driving situation. Although it is possible to reliably cope with this without causing any problems and improve fuel efficiency as well as improve drivability, the cam surfaces (61) and (62) of the cam mechanism (6) can be The parts (61a) and (62a) that function when the input torque is small generate a relatively high axial force, and the parts (61b) and (62b) that function when the input torque is large generate a relatively low axial force. Therefore, even when the input torque to the cam mechanism (6) is small, the slip rate of the slip clutch (5) is reduced and fuel efficiency is reliably improved.At the same time, the input torque to the cam mechanism (6) is large. In this case, by reducing the rate of increase in the axial force generated by the cam mechanism (6) and preventing the generation of excessive axial force, the slip clutch (5)
) and the cam mechanism (6) itself can have sufficient rigidity.

Furthermore, if a centrifugal lock-up clutch (3) is used as the lock-up clutch, the structure becomes extremely simple, as the centrifugal lock-up clutch (3) does not require complicated hydraulic control. , the centrifugal lock-up clutch (3) and the slip clutch (5) are matched to exhibit the above-mentioned performance well, and the lock-up clutch is connected at a relatively low speed by the centrifugal lock-up clutch. As a result, fuel efficiency can be improved.

Note that the above-mentioned symbols in parentheses are used to refer to the drawings, but do not limit the configuration in any way.

Furthermore, although the above-mentioned device is referred to as a starting device, as explained above, it does not function only when starting, but functions throughout the entire running of the vehicle. The name was given because it is easy to understand, and the name itself does not limit the rights in any way.

(g) Examples Examples of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the starting device 1 includes a fluid coupling 2 and a centrifugal lock-up clutch 3. Fluid coupling 2
has a coupling case 23 that can be connected to an engine crankshaft, a pump impeller 22a constituting the input side 22 is provided in the case 23, and a rotor of a hydraulic pump is connected to the hub portion 23a. ing.

Further, a turbine runner 21a constituting the output side 21 is disposed facing the pump impeller 22, and the runner 21a is provided with a thrust bearing 24.2 in the case 23.
The hub part 21b is relatively rotatably supported by a hub part 21b which is positioned and supported via a spline joint part 21 which is connected to the input shaft of the automatic continuously variable transmission.
It has c. On the other hand, a centrifugal lock-up clutch 3 consisting of a friction shoe, a weight assembly, etc. is disposed in the inner diameter portion of the coupling case 23, and the clutch applies a self-energizing effect to the centrifugal force acting on the weight assembly. The lever ratio increases to act on the friction shoe, and is configured to have a large torque capacity at a relatively low rotation speed (for details, see Japanese Patent Application No. 1983).
-331253 and Japanese Patent Application No. 63-331254 (unpublished at the time of filing of this application), furthermore, a disk 31 that rotates together with the friction shoe of the clutch 3 extends in the inner radial direction, and is referred to later as the disk 31. clutch drum 51
A damper spring 32 is interposed between the plate 52 and the plate 52 fixed to the damper spring 32 . The drum 51 of the slip clutch to which the plate 52 is fixed is an annular member having a substantially U-shaped cross section with a corner partially cut out.
a is attached to the stepped portion 23a of the coupling case 23 and the side portion 5.
Bushes 25a and 25 on the side wall of the case 23 or 1b, respectively.
It is supported through b.

A flange portion 26 is provided on the outer diameter side of the hub portion 21b.
A cylindrical member 27 fixed to the inner diameter side of the turbine launch 21a is attached to a thrust bearing 29 on the outer peripheral surface of the boss 26.
It is fitted and supported through. Furthermore, the hub portion 21
A clutch disc 53 and an output cam plate 66 are spline engaged with the boss 26 of b, and a clutch plate 55 and a backup plate 56 are engaged with the inner peripheral surface of the outer diameter portion 51a of the clutch drum 51. and a snap ring 5 fixed to the inner peripheral surface of the drum.
7 and the backup plate 56 is a disc spring 59.
has been reduced. - On the other hand, an input side cam plate 65 is spline engaged with the cylindrical member 27, and a roller 63 is sandwiched between the input side cam plate 65 and the output side cam plate 66. A cam mechanism 6 is configured. Further, the slip clutch 5 is constituted by the inner surface of the side portion 51b of the clutch drum 51, the clutch disc 53, the clutch plate 55, the backup plate 56, and the friction material interposed between these plates 55, 58 and the cam plate 65, 66. has been done. Further, a clutch plate 55 on which the cam mechanism 6 is located
The collar 7 is interposed between the and the backup plate 56.
It is located.

As shown in FIG. 2, the input side cam plate 65 and the output side cam plate 66 in the cam mechanism 6 each consist of an end cam having opposing cam surfaces 61 and 62, and these cam surfaces are arcuate with a predetermined radius. The roller 63 is sandwiched between the rollers 63 and 63. In addition, the fourth
As shown in the figure, the cam mechanism generates the radius R8 of the cam roller 63, the cam end face angle θ, and the input torque T. The smaller tanθ, that is, the cam end face angle θ, the greater the axial force F.
becomes larger. Therefore, as shown in FIG. 2(a), when the roller 63 is located approximately at the center of the cam surface 61, 62, the end face angle θ1 of the cam surface acting portions 61a, 62a that the roller contacts is small, and the cam surface The axial force generated by the relative rotation of 61.62 becomes relatively large, and as shown in Fig. 2(b)
When the roller 63 is located at the end portion of the cam surface 61.62, as shown in FIG.
b.

The end face angle θ of 62b is large (a1 x a2), and the axial force generated by relative rotation of the cam surfaces is relatively small.

Next, the effects of this embodiment will be explained.

When the vehicle starts, the lock-up clutch 3 is in the released state, and the rotation of the engine crankshaft is exclusively controlled by the fluid coupling 2.
is transmitted to the input shaft of the continuously variable transmission. That is,
The rotation of the coupling case 23 causes the pump impeller 22 to
is transmitted from a to the turbine launch 21a via an oil flow,
Further, the rotation of the runner 21a is caused by the rotation of the cylindrical member 27 and the cam mechanism 6.
is transmitted to the hub portion 21b via the spline 2.
1c to an automatic transmission input shaft (not shown). As a result, the vehicle starts moving smoothly. When the vehicle reaches a predetermined speed or higher, the centrifugal lock-up clutch 3 is connected, and the rotation of the engine crankshaft is transmitted to the hub portion 21b via the centrifugal clutch 3, damper spring 32, and slip clutch 5. . In addition, at this time,
The centrifugal lock-up clutch 3 is engaged at a relatively low rotation speed based on self-energizing action and boosting force provided by the lever ratio of the weight assembly. In this state, if a sudden change occurs in the load torque when starting or due to kickdown, upshift, knocking, etc., the slip clutch 5
slips, which causes the fluid coupling 2 to slip on its input side 22.
The power is transmitted to the turbine runner 21a, the cam mechanism 6, the hub portion 21b, and the input shaft of the automatic transmission via the oil flow while rotating relative to the output side 21. At this time, the input side cam plate 65 and the output side cam plate 6 of the cam mechanism 6
6 rotates relative to the load torque as shown in FIGS. 2(a) and 2(b), and the cam surface 61 based on the relative rotation
．． Axial force is generated due to the misalignment of 62. The axial force corresponding to the load torque is applied to the slip clutch 5 in addition to the load pressed by the disc spring 59, and is applied to the clutch plate 55, the clutch disk 53, the backup plate 56, the clutch plate 55, and the cam plate 65.
65, the torque capacity of the slip clutch 5 is increased in response to an increase in load torque. Therefore, for example, during kickdown, the load torque once becomes zero and then suddenly rises, but at the time of this rise, the slip clutch 5 slips, and the power is first transmitted via the fluid coupling 2, and as a result, the load torque suddenly rises. Absorbs fluctuations and accelerates smoothly. Thereafter, the torque capacity of the slip clutch 5 increases in response to the load torque, and power is transmitted with a smooth reduction or elimination of the slip clutch 5, thereby smoothly reducing or eliminating the slip clutch 5 even in a high load torque range. Thus, high transmission efficiency based on the centrifugal lock-up clutch 3 is maintained.

Then, when the lock-up clutch 3 is engaged at a relatively low rotation speed, such as when starting, the input torque passing through the cam mechanism 6 is small, so as shown in FIG. The working portions 61a and 62a of the cam surfaces, which are located approximately in the center of the side cam surface 61 and the output side cam surface 62 and in contact with the roller 63, are located at a portion with a small end face angle 01, and are The axial force increases at a relatively large rate. As a result, as shown in the portion al on the line a of the end face shape R in FIG. 3, the transmission torque (total transmission torque) of the entire starting device 1 is increases rapidly, which can reduce slip ratio and improve fuel efficiency.

In addition, when the input torque via the cam mechanism 6 is large, such as during a stall, the roller 63
is located at the end portions of the input side cam surface 61 and the output side cam surface 62, and the working portion 61b of the cam surface is in contact with the roller 63;
82b is located at a portion where the end face angle a2 is small, and the axial force increases at a relatively small rate with respect to an increase in input torque. As a result, as shown in part a2 on line a in FIG.
The total transmission torque increases gradually relative to the fluid transmission torque, and the components of the slip clutch 5 such as the friction material 53, disc spring 59, and snap ring 57, as well as the cam mechanism 6 itself, are prevented from being damaged by excessive axial force. Can be prevented. Note that the line in FIG. 3 shows the relationship between the fluid transmission torque and the total transmission torque by a cam mechanism using a cam surface with a constant end face angle.

In the above embodiment, the input side cam surface 61 and the output side cam surface 62 are formed by arcs, but the invention is not limited to this, and other curves such as ellipses, straight lines bent at one or more points in the middle, etc. Of course, other shapes may also be used.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a starting device according to the present invention. FIG. 2 is a partially exploded view showing the cam surface, where (a) shows the case where the input torque is small, and (b) shows the case where the input torque is large. Figure 3 is a diagram showing the relationship between the fluid transmission torque and the total transmission torque, and Figure 4 is a diagram showing the generation of axial force by the cam mechanism, where (a) is a partial exploded view of the cam mechanism, and (b) is a roller It is a side view showing the position of. FIG. 5 is a diagram showing the characteristics of a conventional centrifugal lock-up clutch. Output side 21a...Turbine runner 21b...
Hub part, 22...Input side 22a...Pump impeller 23...Coupling case 3
...Centrifugal lock-up clutch, 5...Slip clutch, 51...Clutch drum 53
...Clutch disc 55...Clutch plate 56...Backup plate 57
...Snap ring 59...Disc spring 6...
Cam mechanism 61... Input side cam surface 62...
・Output side cam surface 63...roller, 65...input side cam plate, 66...output side cam plate
θ...End face angle.

Claims (1)

[Claims] 1. A fluid starting device comprising a fluid coupling and a lockup clutch that directly connects an output side and an input side of the fluid coupling, comprising: a slip clutch disposed in series with the lockup clutch; Further, a cam mechanism that generates an axial force corresponding to the load torque is disposed in the power transmission path on the output side of the fluid coupling, and the axial force from the cam mechanism is applied to the slip clutch, and the cam mechanism The cam surface of the cam mechanism is shaped so that a relatively high axial force is generated in the part that functions when the input torque to the cam mechanism is small, and a relatively low axial force is generated in the part that functions when the input torque is large. A slip control device in a fluid starting device, characterized in that: 2. The slip control device in the starting device according to claim 1, wherein the lockup clutch is a centrifugal lockup clutch.