JPH0454359Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a fluid transmission device equipped with a direct coupling clutch for directly coupling an input shaft and an output shaft.

BACKGROUND TECHNOLOGY As is well known, a torque converter, which is an example of a fluid transmission device, has a pump impeller and a turbine runner arranged to face each other, and a one-way connection between an inlet of the pump impeller and an outlet of the turbine runner. It has a stator held by a clutch, and the fluid flow generated by the rotation of the pump impeller, which is integrated with the input shaft, rotates the turbine runner, which is integrated with the output shaft, and transmits torque. It is something. Torque converters have the advantage of absorbing torsional vibrations and shocks due to the relative rotation between the pump impeller and turbine runner, but these characteristics make them less efficient than mechanical transmissions such as clutches. It is the cause of the decline.

Therefore, recently, in order to improve the fuel efficiency of automobiles, torque converters with built-in direct coupling clutches have come into use. FIG. 7 is a schematic cross-sectional view showing an example of this, and FIG. 7 shows the upper half of the rotation center line, where the front cover 1 connecting the input shaft is connected to the pump impeller 2.
A turbine runner 3, which is integrated into the pump impeller 2 and rotates by receiving a fluid flow from the pump impeller 2, is disposed in a hollow chamber formed by the front cover 1 and the pump impeller 2, and the turbine runner 3 is Hub 4 that is fitted and fixed to the output shaft
installed on. Furthermore, a stator 5 is disposed between the inlet of the pump impeller 2 and the outlet of the turbine runner 3, and the stator 5 rotates freely in one direction when receiving fluid from the back side as the rotational speed increases. It is held via a clutch 6.

A clutch piston 7 is directly connected to the outer peripheral surface of the hub 4.
are fitted together. Directly connected clutch piston 7
As shown in the figure, the lining 8 is a disc-shaped member that almost follows the inner surface of the front cover 1, and the lining 8 for transmitting torque by pressing the direct coupling clutch piston 7 is attached to the inner surface of the front cover 1. It is provided at a predetermined location. The direct coupling clutch piston 7 and the turbine runner 3 are connected by a torsional damper mechanism 13 consisting of a turbine drive plate 9, a spring guide plate 10, a coil spring 11, and a damper spring location 12. The torque is transmitted substantially through the torsional damper mechanism 13, and the torque is damped in the rotational direction.

In FIG. 7, the reference numeral 14 indicates a thrust washer between the front cover 1 and the hub 4, and the reference numeral 15 indicates a thrust bearing.

Therefore, as shown in FIG. 8A, by supplying hydraulic pressure to the side opposite to the front cover 1 to the direct coupling clutch piston 7, the direct coupling clutch piston 7 moves forward and contacts the front cover 1 through the lining 8. As a result, these front cover 1, direct coupling clutch piston 7 and spring location 12, coil spring 11,
The input shaft and the output shaft are directly connected via the drive plate 9 and the hub 4. Further, as shown in FIG. 8B, if hydraulic pressure is supplied between the front cover 1 and the direct coupling clutch piston 7, the direct coupling clutch piston 7 will retreat and separate from the front cover 1.
As a result, the input shaft and the output shaft are connected via the pump impeller 2 and the turbine runner 3, similar to a normal torque converter.

By the way, as mentioned above, torque converters transmit torque through fluid, so they are excellent at absorbing torsional vibrations and shocks. Although efficiency is improved due to the symmetrical connection, vibration and shock absorption characteristics are reduced. Therefore, in the past, as shown in FIG. 7, a torsional damper mechanism 1 consisting of a drive plate 9, a coil spring 11, a spring location 12, etc.
However, the vibration damping ability of such a configuration is not necessarily sufficient; for example, it absorbs vibrations that occur when switching to a direct connection state at low speeds, or when suddenly accelerating or decelerating in a direct connection state. Vibration cannot be suppressed sufficiently. Therefore, we changed to a damper mechanism using coil spring 11,
Configuration that uses a viscous damper that utilizes the viscosity of silicone oil (Magazine "Automotive Technology" Vol. 39, No.
6, p. 644) and a torque converter (Japanese Patent Application Laid-open No. 40162/1983) in which the ratio between the rotational strain of the damper and the acting torque changes in two stages has been proposed.

Problems to be solved by the invention However, in the case of a viscous damper, not only is there a risk of slippage occurring and deterioration of torque transmission, but also the use of hydraulic oil for hydraulic control and silicone oil for the damper is difficult. There is a problem that the structure for separation becomes complicated. On the other hand, the above-mentioned JP-A-Sho
Although the structure described in No. 57-40162 can alleviate the engagement shock caused by lock-up during low-speed driving, this is affected by how lock-up oil pressure is applied, and it is difficult to prevent sudden lock-up. If this is done, there is a high possibility that an engagement shock will occur. On the other hand, if the lock-up oil pressure was applied gradually, there was a risk that the direct coupling clutch piston 7 and the lining 8 would slip, and the friction material would wear out prematurely.

In view of the above-mentioned circumstances, this idea was developed to reduce the relative rotational speed difference when engaging and disengaging the direct coupling clutch as much as possible, thereby suppressing the vibrations associated with the engagement and disengagement of the direct coupled clutch. The purpose of this invention is to provide a transmission device.

Means for Solving the Problems In order to achieve the above object, this invention provides a turbine runner that faces the pump impeller and is provided inside a hollow chamber formed by the pump impeller and the front cover integrated therewith. and a direct-coupled clutch piston, a portion of which is pressed against and released from the front cover by moving forward and backward using hydraulic pressure. A viscous transmission mechanism is provided at a portion facing the front cover and the transmission torque capacity increases through the viscous fluid as the distance between the other portion and the front cover decreases. This is a characteristic feature.

Therefore, in this invention, when the direct-coupled clutch piston is moved forward toward the front cover to achieve the direct-coupled state, the gap between the direct-coupled clutch piston and the front cover becomes small, and as a result, these When the torque of the front cover is gradually transmitted to the direct-coupled clutch piston by the viscous transmission mechanism installed on the opposing part, the rotational speed of the direct-coupled clutch piston approaches the rotational speed of the front cover, and the difference between the rotational speeds of the two becomes almost zero. The directly connected clutch piston is pressed against the front cover. That is, the rotational speed of the direct coupling clutch piston is increased by the viscous transmission mechanism, and then the direct coupling clutch piston and the front cover are engaged with each other.

Embodiments Hereinafter, embodiments of this invention will be described with reference to the drawings.

Fig. 1 is a sectional view of the main parts showing one embodiment of this invention.The basic structure of this torque converter is the same as the general structure shown in Fig. 7, so to explain the different parts, the front cover 1, a large number of annular protrusions 16 centered on the axis are provided on the inner surface of the part facing the direct coupling clutch piston 7.
are formed concentrically, and the inner and outer circumferential surfaces of the protrusions 16 are tapered so that they become thinner on the tip side, and therefore the inner surface of the front cover 1 is an uneven surface. On the other hand, a large number of annular protrusions 17 are formed on the front surface of the direct coupling clutch piston 7, which is the part facing the front cover 1, which engages with the protrusions 16 without contacting them.
Also, the inner and outer circumferential surfaces of the clutch piston 7 are tapered surfaces, and the front surface of the direct coupling clutch piston 7 is also an uneven surface similarly to the front cover 1.

Here, the protrusion 1 has tapered inner and outer circumferential surfaces.
The reason why pistons 6 and 17 are provided is to increase the surface area, increase the opposing area of the two as the direct coupling clutch piston 7 moves forward, and minimize the distance between them. That is, these protrusions 16, 17 and the oil filled between them constitute a viscous transmission mechanism.

Therefore, in the above-mentioned torque converter, the distance d between the front cover 1 and the direct coupling clutch piston 7 is widened as shown in FIG.
When lock-up oil pressure is applied to the rear side (right side in the figure), the direct coupling clutch piston 7 moves forward, and the distance d between it and the front cover 1 narrows as shown in FIG. 2B. Since oil fills the space between these direct-coupled clutch pistons 7 and the front cover 1, as the distance d becomes smaller, the shear cross section for the oil increases, and in this case, the distance d and the torque transmission coefficient C are Since the relationship is inversely proportional as shown in FIG. 3, the force transmitted from the front cover 1 to the direct coupling clutch piston 7 via the oil increases. Therefore, the rotation speed of the direct coupling clutch piston 7 is increased just before it is pressed against the front cover 1, and then it is pressed against and engaged with the lining 8 of the front cover 1.
As a result, smooth engagement is achieved.

This situation can be illustrated in a diagram as shown in Figure 4. When the lock-up oil pressure starts to be applied and the direct coupling clutch piston 7 gradually moves forward, the shear cross section of the oil increases due to the provision of the protrusions 16 and 17. As a result, the transmitted force gradually increases as shown by the broken line in FIG. The longitudinal acceleration G of the vehicle during this process increases as the transmitted force increases, as indicated by the broken line in FIG. 4, reaches a maximum when the transmission is directly connected, and immediately decreases slightly thereafter. In contrast, in the past, the rotational force was transmitted only after the direct coupling clutch piston 7 came into contact with the lining 8, so the transmitted force was transferred to the fourth
As shown by the solid line in the figure, it increases rapidly, and as a result,
Due to the elasticity of the damper mechanism 13 and other mechanical systems, the longitudinal acceleration G of the vehicle increases or decreases as shown by the solid line in FIG. 4, resulting in a so-called lock-up shock.

That is, in the torque converter according to this invention, the direct coupling clutch can be engaged without generating vibration or shock.

In addition, if the structure is such that the friction material 18 is provided in the concave portions of the uneven surfaces of the front cover 1 and the direct coupling clutch piston 7 as shown in FIGS. 5A and 5B,
By increasing the engagement area between the front cover 1 and the direct coupling clutch piston 7, slipping can be prevented,
Further, direct contact between the protrusions 16 and 17 can also be prevented.

FIG. 6 shows another embodiment of this invention, and in the torque converter shown here, the shape of the opposing portion between the front cover 1 and the direct coupling clutch piston 7 is different from that of the above-mentioned embodiment. It is something. That is, a portion of the inner surface of the front cover 1 that is closer to the center than the lining 8 is a wavy curved surface 19 that continuously and smoothly protrudes and retracts in the axial direction, and the front surface of the direct coupling clutch piston 7 is a similar wavy curved surface 20. The two are almost parallel to each other. Even with this configuration, the surface area of both is increased and the shear cross section of the oil is increased as the two approach each other due to the advancement of the direct coupling clutch piston 7, and the torque transmission coefficient C is increased. As in the above example, it is possible to switch to the direct connection state without causing vibration or shock.

Note that this invention is not limited to the torque converter shown in the above embodiment, and can be widely applied to fluid transmission devices that transmit torque via fluid.

Effects of the invention As is clear from the above explanation, according to the fluid transmission device of this invention, the direct-coupled clutch piston engages with the front cover and transmits torque to the opposing portions of the front cover and the direct-coupled clutch piston, respectively. Since we have provided a fluid transmission mechanism that transmits torque by the direct coupling clutch piston approaching the front cover prior to the engagement of the direct coupling clutch, torque is already transmitted from the front cover to the direct coupling clutch piston before the direct coupling clutch engages. The rotational speed of the piston increases, and the rotational speeds of both pistons become approximately equal just before direct connection, so that smooth engagement without vibration or impact can be achieved.

[Brief explanation of the drawing]

Figure 1 is a schematic sectional view showing an embodiment of this invention, Figures 2A and B are partial views showing part of its protrusions, and Figure 3 shows the distance between the front cover and the direct-coupled clutch piston. Figure 4 is a diagram showing the relationship between the torque transmission coefficient, Figure 4 is a diagram to explain the transmission force and the occurrence of vibration during engagement, and Figures 5A and B are diagrams showing the relationship between the front cover and the directly connected clutch piston. FIG. 6 is a schematic cross-sectional view showing another embodiment of this invention, and FIG. 7 is a schematic view showing an example of a conventional torque converter with a direct coupling clutch. The cross-sectional view and FIGS. 8A and 8B are explanatory diagrams of its operation. 1...Front cover, 2...Pump impeller, 3...Turbine runner, 7...Direct clutch piston, 8...Lining, 16, 17...
Projections, 19, 20...wavy curved surface.

Claims (1)

[Claims for Utility Model Registration] Inside a hollow chamber formed by a pump impeller and a front cover integrated therewith, there is a turbine runner facing the pump impeller, and a turbine runner that moves back and forth by hydraulic pressure with respect to the front cover. In a fluid transmission device in which a direct-coupled clutch piston is housed, a part of which is pressed into and separated from the direct-coupling clutch piston, a part of the direct-coupled clutch piston other than the part and the front cover are opposite to each other. 1. A fluid transmission device with a direct coupling clutch, characterized in that a viscous transmission mechanism is formed in which the transmission torque capacity increases as the distance between the front cover and the front cover decreases.