192 clutches and power-stop control – Clutch and brake – Sliding operation
Reexamination Certificate
1999-10-15
2001-02-13
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutch and brake
Sliding operation
C192S052600, C192S056330, C464S036000
Reexamination Certificate
active
06186297
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
A bi-directional, variable torque output clutch utilizing a ring of spherical members compressed between layers of resilient material.
2. Description of the Prior Art
Conventional clutch devices operate on the principle of sliding friction and consists of a pair of friction discs arranged axially wherein one friction disc is attached to the device input shaft and the opposing friction disc is attached to the output shaft. Various techniques are used to provide a force which presses the two friction discs together. Energization of the driver (motor) results in an angular torque output which is limited by numerous factors including the applied force, coefficient of friction of the discs, etc. In these prior art designs, static-dynamic friction transitions occur, an undesirable characteristic. This is the primary cause for devices which operate on the sliding friction principle tend to skip and chatter and cause uneven start-up operation. Further, sliding friction type devices tend to wear faster than devices based on the concept of rolling friction. A prior art device which improves upon the conventional clutch devices utilizes magnetic particles, such as the model no. CB35DF3, manufactured by Force Limited, Santa Monica, Calif. In this device, clutching and braking functions are provided by the magnetic particles.
Systems in which the magnetic particle clutch device is utilized tend to have problems wherein rapid, braking forces are required. For example, in container inspection systems wherein containers are moved along a conveyor belt and wherein the containers are visually examined to ascertain if the containers are filled, damaged, etc. occasions have arisen wherein the bottles are stopped but the clutch drive is still engaged which causes excessive heat build up inside the clutch. If the condition is sustained for a long time period, the magnetic particles tend to fuse together, effectively damaging the clutch to the point wherein it has to be replaced. The magnetic particle based clutch is also relatively expensive.
In addition, most prior art clutch devices having output torque limiting features typically have one operating torque value. Those devices which provide adjustable torque capabilities tend to be cumbersome, expensive and unreliable.
SUMMARY OF THE PRESENT INVENTION
The present invention provides a bidirectional controllable torque transmission device which drives a machine element with an adjustable torque limiting capability. The input shaft is connected to a driver and the output shaft is connected to the machine element. The clutch mode of operation provides an adjustably limited torque output value causing rotation of the machine element; the braking mode of operation provides an adjustable braking torque capable of stopping the rotating machine element upon cessation of the torque transmission. The assembly provides either driving or braking actions as required. In a preferred mode, the device of the present invention is used to drive a container inspection conveyor line.
The brake portion of the device consists of a rotor, circular brake pad and two pistons arranged 180 degrees apart (additional pistons can be used as long as they are equidistant about the assembly axis). Compressed air is introduced into the bearing housing through a port and is entrapped inside the cylinder walls. The resultant pressure exerts a force on the pistons, causing the rotor to be pressed against the brake disc, thus stopping the rotation of the output shaft. In the clutch portion of the present invention, a plurality of balls are positioned between a pair of discs made of resilient deformable material, such as urethane. The rotor compresses the balls between the two discs when air pressure is introduced into the system, causing resistance to the rolling action of the balls. The torque input is thus transferred to the output side; if the pressure is varied, the amount of indentation will vary, the output torque thus changing accordingly and thereby providing a simple and convenient technique for adjusting the output torque. The braking mode of operation is similar in that varying the air pressure varies the braking torque. Both braking and torque transmission modes of operation cease when air pressure is no longer applied to the system.
The present invention thus provides an improved clutch assembly that provides smooth starts and chatter free slippage at a reduced cost and wherein the wear associated with conventional clutch assemblies is significantly reduced.
REFERENCES:
patent: 2683362 (1954-07-01), Bowman
patent: 3166167 (1965-01-01), Kinsman
patent: 3174350 (1965-03-01), Harnish et al.
patent: 3509974 (1970-05-01), Kampert et al.
patent: 3556272 (1971-01-01), Jones
patent: 4286441 (1981-09-01), Scheneman et al.
Bonck Rodney H.
Industrial Dynamics Company, Ltd.
Keschwer Irving
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