ANTI-JAMMING CLUTCH MECHANISM
FOR A CLAMPING APPARATUS
BACKGROUND OF THE INVENTION
The present invention is directed toward clutch mecha- 5 nisms and, more specifically, to clutch mechanisms for clamping apparatuses that are movable between a clamping position and a fully open position. Still more specifically, the present invention is directed toward a clutch mechanism for a clamping apparatus that biases the male and female clutch 10 elements together when the clamping apparatus is in a fully open position to prevent clutch slippage in the fully open position.
Clamping mechanisms are employed in a number of different apparatuses, one type of which includes mixing apparatuses. Specifically, apparatuses that mix materials in a container by shaking or vibrating require a clamping mechanism to hold the container in place during the mixing process. An example of such a mixing apparatus is shown 2Q and described in the commonly assigned U.S. Pat. No. 5,711,601, the disclosure of which is incorporated herein by reference as if fully set forth herein.
Clamping apparatuses that are used to hold containers and other objects in position on a support plate or between two 25 clamping plates typically include a clutch mechanism to prevent overtightening of the clamp mechanism. Typically, the clutch mechanism includes a female clutch plate with a plurality of grooves for accommodating teeth of the opposing male clutch plate. The teeth of the male clutch plate are 30 typically angled in one direction thereby enabling the teeth to slip out of the grooves if the clamping mechanism and clutch plates are rotated with a force sufficient to cause overtightening of the clamp mechanism. Thus, clutch slippage is intended to be allowed in only one rotational 35 direction (i.e. clamp tightening) and locked in an opposite direction (i.e. clamp loosening).
In addition to having a fully clamped or clamping position, clamp mechanisms typically have a fully open or release position which is arrived at when the moving clamp 40 member engages a stop or frame member that prevents any further rotation of the clamp mechanism in the open direction. A problem has arisen in connection with these types of clamp mechanisms because operators who are attempting to work at a fast pace have the tendency of rotating the clamp 45 mechanism in the open direction to the extent where the clamp mechanism can become jammed in the fully open position. Specifically, the operator will rotate the clamp mechanism towards the fully open position at such a rate that the moving clamp member becomes tightened against the 50 stop or frame member that prevents any further movement towards the open position. This inadvertent tightening must be overcome by rotating the handle or actuator of the clamp mechanism back towards the clamping direction. However, as discussed above, clamping systems include a clutch 55 mechanism which is designed to slip in the event the operator attempts to overtighten the clamping system in the closed or clamped position. The force required to cause the male and female clutch elements to slip is often small enough so that the male and female clutch elements often go slip when the operator is attempting to unjam the clamping apparatus from the fully open position.
In short, by overtightening the clamp apparatus into the fully open position, the clutch mechanism, which prevents overtightening of the clamping apparatus in the clamped or 65 closed position, can also prevent the unjamming of the clamping apparatus from the jammed fully-open position.
As a result, the apparatus must be disassembled in order to unjam the clamping apparatus. Of course, this causes great inconvenience and makes the mixing apparatus unusable until the clamping mechanism is unjammed.
As a result, there is a need for an improved clamping mechanism for mixing apparatuses and other apparatuses that employ a clamping mechanism which can prevent the clamping mechanism from being jammed in the fully open position while permitting the clamping mechanism to employ a clutch mechanism to prevent overtightening of the clamping mechanism in the clamped or fully closed position.
SUMMARY OF THE INVENTION
In accordance with the present invention, an apparatus is provided for releasably clamping an object in a position. The apparatus includes a support member for engaging the object to be held in position, the object being held between the support member and a traveling member. The traveling member is movable towards a clamping position with the object being clamped between the support member and the traveling member as well as a fully open position whereby the traveling member approaches, but does not engage a stationary member.
The traveling member is threadably mounted onto at least one threaded shaft that is connected to the stationary member and extends towards the support member. The threaded shaft is linked to a rotatable gear which engages a clutch mechanism that includes a female clutch plate and a male clutch plate. The clutch mechanism also is linked to a lever arm, the clutch mechanism being disposed between the stationary member and the lever arm. The gear is also disposed between the stationary member and the clutch mechanism.
Rotation of the lever arm, when the male and female clutch plates are in a mating engagement, imparts rotation to the male and female clutch plates, the gear and the threaded shaft thereby causing the traveling member to move along the threaded shaft either towards a clamping position or towards the,object to be clamped or towards an open position or away from the object to be clamped.
The stationary member accommodates at least one pin that is slidably received in an aperture disposed in alignment with both the gear and the clutch plates. The traveling member engages the pin when the apparatus is rotated towards the fully open position which causes the traveling member to move towards the stationary member. Before the traveling member engages the stationary member, the traveling member engages the pin which pushes the gear against the clutch plates thereby resulting in a biasing of the clutch plates together resulting in a mating engagement of the clutch plates which prevents clutch slippage in the fully open position.
Accordingly, the pin provides two benefits. First, the pin biases one clutch plate against the other clutch plate thereby preventing clutch slippage in the fully open position and, further, the pin prevents the traveling member from fully engaging the stationary member and therefore prevents the traveling member from being overtightened against the stationary member in the fully open position. Thus, the pin and the modified support member prevents the clamping apparatus from being jammed in the fully open position while allowing the clamping apparatus to employ a clutch mechanism which also prevents the clamping apparatus from being overtightened in the clamping position.
In an embodiment, the clamping apparatus of the present invention further comprises at least one spring member