192 clutches and power-stop control – Clutches – Automatic
Patent
1992-06-26
1994-07-12
Bonck, Rodney H.
192 clutches and power-stop control
Clutches
Automatic
192 65, F16D 4106
Patent
active
053280121
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a rolling-contact bearing type clutch which functions as a one-way clutch rotatable only in one direction.
BACKGROUND OF THE INVENTION
One-way clutches have been available in the prior art. A conventional typical one-way clutch is shown in FIG. 8, in which cylindrical rollers 3 are arranged in between the raceway tracks of the inner and outer rings 1 and 2, and the inner raceway surface of the outer ring 2 is formed into saw-like cams to bring the inner and outer rings 1 and 2 into clutch condition in reverse rotation by engaging the cylindrical rollers with the cam surfaces 2c on the outer ring 2. Another traditional one-way clutch is one in which both raceway surfaces of the inner and outer rings are cylindrical, and cam-like sprags are arranged in between the inner and outer rings in place of the cylindrical rollers 3 of the former, to have sprags engaged with the raceway surfaces in reverse rotation by spring force. With the above described clutches according to the prior art, in the reverse rotation (to be placed into clutch condition), the inner and outer rings 1 and 2 are brought into clutch condition by engaging the rollers 3 with the cam-like inner surface portions 2c on the outer ring 2 which are not circular or uneven in the radial direction, while in the normal rotation (free rotation) the rollers 3 are allowed to slide freely between the inner and outer rings 1 and 2. However, since the thrust angle .alpha. must be smaller than the friction angle, formation of a cam within the pitch P of the sprag rollers 3 would restrict the cam height, thus causing a possibility of rollers overriding cam portions 2c to damage the clutch.
An even and sufficient clutch force to be desired in the clutches according to the prior art necessitates a condition in which incorporated rollers or sprags respectively are evenly engaged with each corresponding cam surface. A limited dimensional accuracy of the components and a limited uniformity of spring forces to push the rollers in the clutch direction may impose a challenge to the clutches in obtaining uniform clutch forces.
On the other hand, a transmission clutch force to be generated in the clutch operation must have surface pressures between all the surfaces and the corresponding rollers (or sprags) to be in proportion to the required transmission torque and stable within the allowances. For this purpose, however, all the rollers must participate simultaneously in the clutch operation, and wedge forces between all the surfaces and the corresponding rollers to be produced by the clutch operation must uniformly increase or decrease as the required transmission torque will increase or decrease. There may be, however, many limitations for maintaining the allowable surface pressure such as: for original (as manufactured) dimensional accuracy of each component e.g., especially cam shape to be machined; for original (as built) uniformity of relational dimensions between rollers and clutch surfaces to be maintained by bearings; and due to deformations of the inner and outer rings associated with contact pressure between ring contact surface and roller as well as due to their wear. Particularly, this kind of clutch has the basic constraints that in the free rotational operation two separate bearings will freely support the clutch shaft, and the rollers will freely slide on the cam surfaces. The constraints may impose a critical challenge to the wear of the raceway surface and sprag roller in the clutches according to the prior art.
Further, the cams to be formed in the one-way clutches according to the prior art have posed manufacturing difficulties for material and heat treatment for hardness, and machining accuracy for hardened surface. Such critical conditions, when calculating the Herts' stress in the design of allowable surface pressure, forces selection of undesirable values of parameters.
To solve these problems, (Japanese Patent Publication No. 1983-59092 discloses clutches), wherein inner and outer rings are fo
REFERENCES:
patent: 1670197 (1928-05-01), Humfrey
patent: 1834843 (1931-12-01), Humfrey
patent: 3557921 (1971-01-01), Takada
patent: 3800927 (1974-04-01), Takata
patent: 4462490 (1984-07-01), Hattori
patent: 5035309 (1991-07-01), Takada
patent: 5067601 (1991-11-01), Castens
patent: 5109964 (1992-05-01), Fukui et al.
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