1. Field of the Invention
The present invention relates to an apparatus for holding springs of a clutch, particularly to shock-absorbing springs for a clutch plate which are used in a direct-coupling clutch of a fluid torque converter, or the like.
2. Description of the Related Art
A direct-coupling clutch for a fluid torque converter is disclosed, for example, in Published Examined Patent Application No. 9780/1987. An apparatus for holding shock-absorbing springs in this direct-coupling clutch has a construction shown in FIG. 12A. In the figure, reference mark "a" is a clutch plate. On a front side (i.e., left side in FIG. 12A) of the clutch plate "a", there is adhered a friction member b. On a rear side (i.e., right side in FIG. 12A) thereof, there is formed an annular recessed portion c. A shock-absorbing spring d is held inside this recessed portion c by means of a wear-resistant guide plate e and a retainer f. The retainer f has end surface holding portions f.sub.1 for holding both end portions of the spring d, and periphery holding portions f.sub.2 for holding the periphery thereof. The retainer f is fixed to the clutch plate "a" with rivets g after overlapping it with the guide plate e. In the figure, reference mark h is an input case, i is a turbine, and i.sub.1 are projection pieces which extend from the turbine i to abut with both ends of the spring d.
In this apparatus, as shown in FIG. 12B, prior to fixing with rivets g, the guide plate e and the retainer f are assembled in advance by caulking a small projection f.sub.3 which protrudes or projects from the retainer f into a small hole e.sub.1 which is provided in the guide plate e. However, the guide plate e is likely to give rise to distortions because it is made of a thin plate and is further heat-treated. Therefore, the portion which is overlapped with the retainer f presents remarkable distortions because it is planar and is wide in lateral width. Consequently, it sometimes happens that a clearance occurs between the guide plate e and the retainer f in a portion away from the portion that is caulked by the small projection f.sub.3. Even if the pre-assembled parts are caulked onto the clutch plate "a" with rivets g as shown in FIG. 12A, the above-described distortion will remain, resulting in a disadvantage in that there will be left a clearance between the guide plate "a" and the retainer f or the clutch plate e.
Further, in order to minimize the number of parts, it is considered to make the arrangement, as shown in FIG. 13, that a small projection j is provided in a clutch plate "a" and that the guide plate e and the retainer f are caulked at the same time without pre-assembling them. However, it is considerably difficult to protrude or project the small projection j into a height enough to caulk the guide plate e and the retainer f together. In addition, the guide plate e may be distorted to thereby increase in height. As a result, the height of the small projection j is likely to become insufficient in plate thickness at a caulking head portion j.sub.1. Further, due to the distortion in the guide plate e, the clearance as described above is likely to remain between respective plates.
The present invention has an object of providing an apparatus for holding a spring of a clutch in which the retainer can be mounted on the clutch plate without giving rise to a clearance.