192 clutches and power-stop control – Clutches – Automatic
Reexamination Certificate
2000-01-27
2001-07-10
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Automatic
C192S043100
Reexamination Certificate
active
06257384
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a two-way differential clutch using sprags.
In part-time four-wheel drive vehicles, an overrunning type two-way differential clutch is used to automatically transmit the driving force to the front vehicle wheels as soon as a rear wheel slips and the vehicle speed drops.
In unexamined Japanese patent publication 9-25959, an overrunning type two-way differential clutch using sprags is disclosed. It includes two retainers having different diameters and mounted between the outer circumferential surface of a rotary shaft and the inner circumferential surface of an input gear mounted on the rotary shaft. The large-diameter retainer is fixed to the input gear while the small-diameter one is rotatably supported on the rotary shaft so as to create a differential speed between the small-diameter retainer and the large-diameter retainer, which rotates together with the input gear, due to a frictional resistance applied to the small-diameter retainer so that sprags mounted to straddle pockets formed in both of the retainers will be inclined or tilted to a standby state in which they contact at both ends thereof the outer circumferential surface of the rotary shaft and the inner circumferential surface of the input gear. Thus, when the rotating speed of the rotary shaft drops below that of the input gear, the sprags are brought into an engaging state to transmit the rotation of the input gear to the rotary shaft.
With such a two-way differential clutch, when the rotating direction of the input gear changes over, the inclining direction of the sprags also changes automatically. Thus it is possible to transmit the rotation of the input gear in either direction to the rotary shaft.
In many cases, as a means for giving a rotational resistance to the small-diameter retainer, an arrangement is employed in which a flange is provided on the outer surface of the small-diameter retainer at its end protruding beyond one end of the input gear, a friction plate provided on one side of the flange being supported so as to be movable in the axial direction of the small-diameter retainer, and the friction plate being pressed against the flange by a partially cut-apart resilient ring supported on the small-diameter retainer.
In this two-way differential clutch, if such a resilient ring is used as a resistance-imparting means for imparting a frictional resistance to the small-diameter retainer, it may expand radially outwardly during high-speed rotation, thus coming off its position. In such a case, a frictional force between the friction plate and the flange will disappear, so that the small-diameter retainer becomes freely rotatable. The two-way differential clutch thus becomes inoperative to exhibit its function as a clutch. #
Also, for such a two-way differential clutch, since the input gear and the small-diameter retainer are rotatably supported by respective rolling bearings mounted on the rotary shaft and both ends of the rotary shaft are rotatably supported by two rolling bearings, when the clutch is assembled, an assembling step in which four rolling bearings are pressed is needed, so that it takes a long time to assemble. Thus, there is room for improvement in assembling it.
Also, after pressing, the rolling bearings need setting of clearance. At this time, since the clearance setting range is wide due to variations in e.g. tolerances of the parts at the press-in portion, it is difficult to obtain high-precision assembling. Thus, improvement in the assembling accuracy is required.
An object of this invention is to provide a two-way differential clutch which can prevent the resilient ring for biasing the friction plate from expanding radially outwardly and getting off the mounting position due to centrifugal force during high-speed rotation.
A second object of this invention is to improve assembling properties and assembling accuracy of a two-way differential clutch.
SUMMARY OF THE INVENTION
According to this invention, there is provided a two-way differential clutch comprising a rotary shaft rotatably supported by rolling bearings, an input gear rotatably supported on the rotary shaft by a rolling bearing, an output gear provided on one side of the input gear so as to be rotatable about the rotary shaft, two retainers having different diameters and mounted between an outer circumferential surface of the rotary shaft and an inner circumferential surface of the input gear one upon the other, a small-diameter one of the retainers rotatably supported by a rolling bearing mounted on the rotary shaft and a large-diameter one of the retainers mounted on the small-diameter retainer so as to rotate together with the input gear, a flange provided on the outer circumference of one end of the small-diameter retainer protruding beyond one end of the input gear, a friction plate and a partially cut-apart resilient ring provided at one side of the flange, the resilient ring pressing the friction plate against the flange, and sprags mounted to straddle pockets formed in the two retainers so as to be inclined until both ends of the sprags come into contact with an outer circumferential surface of the rotary shaft and an inner circumferential surface of the input gear by relative rotation of the small-diameter retainer and the large-diameter retainer, characterized in that the friction plate is provided with a restricting portion for restricting the amount of radial expansion of the resilient ring.
By providing the restricting portion on the friction plate, it is possible to prevent the resilient ring from radially expanding excessively due to centrifugal force. Thus, it is possible to always retain the resilient ring in the position where it presses the friction plate and to allow the two-way differential clutch to function reliably.
The restricting portion may be a cut-and-raised piece in which two rows of cuts are formed in the friction plate and the portion between the cuts is raised toward the resilient ring.
With such a two-way differential clutch, if the output gear were coupled to the rotary shaft by splines, when the input gear stops from the forward-rotation state and changes over to the reverse-rotation state, if the rotating speed of the rotary shaft, which is reversed from the wheel-side gear through the output gear, is higher than the rotating speed of the input gear, since the sprags are returned to their neutral position by contact with the rotary shaft, it is impossible to transmit the reverse rotation of the input gear to the rotary shaft.
In order to avoid such inconvenience, a torque transmission mechanism for transmitting the rotation of the rotary shaft to the output gear is provided between the rotary shaft and the output gear, a play in the rotational direction is formed in the torque transmission mechanism, the friction ring is made nonrotatable relative to the rotary shaft, the sub-gear for generating a differential speed with the rotation of the output gear and the partially cut-apart resilient ring for pressing the sub-gear against the flange provided on the outer surface of the friction ring are mounted on the friction ring, and the restricting portion for restricting the amount of radial expansion of the resilient ring is provided. By employing such an arrangement, when the rotational direction of the input gear changes, the rotary shaft is braked and decelerated due to frictional resistance acting on the contact portion between the sub-gear and the flange until the play in the torque transmission mechanism disappears. Thus, the sprags instantly engage the inner surface of the input gear and the outer surface of the rotary shaft, so that it is possible to instantly transmit the rotation of the input gear to the rotary shaft.
Also, by providing the restricting portion for restricting the amount of radial expansion of the resilient ring on the sub-gear, it is possible to prevent excessive radial expansion of the resilient ring due to centrifugal force during high-speed rotation.
According to the present invention, at least one of inne
Komuro Masao
Saiko Masaaki
Sato Koji
Lorence Richard M.
NTN Corporation
Wenderoth , Lind & Ponack, L.L.P.
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