EP0934803A1

EP0934803A1 - Double supported plunger clamp

Info

Publication number: EP0934803A1
Application number: EP98300869A
Authority: EP
Inventors: Henry Dykstra
Original assignee: Delaware Capital Formation Inc; Capital Formation Inc
Current assignee: Delaware Capital Formation Inc; Capital Formation Inc
Priority date: 1998-02-05
Filing date: 1998-02-05
Publication date: 1999-08-11

Abstract

A plunger clamp that provides a positive clamping force in each direction and an over center locking force in each direction, both while providing a low profile relative to the axis of the clamping force when closed in either direction. The clamp has a toggle arm pivotally connected to the plunger support above the axis of the plunger to allow the plunger to clamp at each end of its stroke, without requiring a 180° rotation of the handle.

Description

Field of the Invention:

The present invention broadly relates to a plunger clamp apparatus, and more particularly, relates to a low profile plunger clamp assembly wherein the plunger can be locked in either a closed or open position.

Background of the Invention:

Plunger or toggle clamps have been long known in the industry which provide a lever arm connected through a linkage to move a cylindrical plunger into a locking position. The linkage generally consists of a pivot point for the lever arm which is on the plane of the motion of the plunger and a pivot point where the linkage is attached to the plunger which is by definition also on the same plane. The third part of the linkage, the pivot point connecting the lever arm to the driving linkage, rotates generally about the pivot point of the lever arm and either aligns with the other two pivot points when the clamp is in the clamping position, or goes slightly past the plane of the other two pivot points, creating an over-center or locking position. Such plunger clamping devices often require an additional locking mechanism such as a releasable locking latch to prevent the clamp mechanism from opening. An example of this type of mechanism and clamping device is shown in U.S. Patent No. 5,165,418 to Fleischer, et al. Such devices provided clamping force at only one end of the plunger, and in the closed position have a lever arm protruding well above the clamping axis of the plunger. The handle for this clamp must travel a full 180°, which typically requires the handle to be lowered past the clamping plane to generate a locking force in the pull clamping position. Further, prior art mechanisms utilize a forged base which is difficult and expensive to manufacture, which have only a single support for the plunger and which necessarily are limited to one particular clamp size.
The present invention provides a plunger-type clamp which provides positive clamping force in each direction, which provides an over-center locking force in each direction and yet which provides a low profile relative to the axis of the clamping force when closed in either direction. Further, the present invention provides two separate supports for the plunger and utilizes a base which may be machined from stainless steel.
Wherefore, it is an object of the present invention to provide a design of a plunger clamp with a low profile relative to the axis of the clamping source.
Another object of the invention is to provide a toggle clamp which does not require a full 180° rotation of the handle to lock for clamping in each direction of the travel of the handle.
Another object of the present invention is to provide a design of a plunger clamp having a base that may be easily machined and which supports the plunger at two separate points.
Still another object of the invention is to provide a design of a plunger clamp capable of clamping in two directions.
Another object of the invention is to provide a design of the plunger apparatus that is capable of locking the plunger without a locking latch.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and the advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

Summary of the Invention:

According to the present invention, the foregoing and other objects and advantages are obtained by a plunger clamp having at least one support with an elongated plunger slidably held within the support, at least one toggle lever pivotally mounted to the support at a first axis positioned above the plane of the axis of the plunger, and at least one locking arm cooperating between the plunger and the toggle lever. The locking arm is pivotally connected to the toggle lever at a second axis and pivotally connected to the plunger at a third axis in which the locking arm translates the angular motion of the toggle lever to drive the plunger along a longitudinal axis between a closed and open position responsive to movement of the toggle lever. The actuation of the lever arm translates the axis of the second pivot point from a point beneath the plane defined by the first and third axes when in the closed position through a path above that plane and past the new plane defined by the first and third axes in the open position. The plunger generates a clamping force in each direction and is held in position at each end of its travel by the over-enter orientation of the linkage.

Brief Description of the Drawings:

Figure 1 is a side view of the present invention with the plunger clamped in the closed position.
Figure 2 is a view similar to Figure 1 showing the plunger in a clamped open position.
Figure 3 is a view similar to Figure 1 where the plunger is clamped closed and safety locked by a safety latch element.
Figure 4 is a top view of the present invention with the plunger clamped in the closed position.
Figure 5 is a top view of the present invention similar to Figure 4 with the plunger clamped in the open position.
Figure 6 is a sectional view of Figure 1 along lines 6-6.
Figure 7 is a second embodiment of the present invention incorporating a pneumatic source activating the plunger in a closed position.
Figure 8 is similar to the view in Figure 7 with a pneumatic source clamping the plunger in an open position.

Description of the Preferred Embodiment(s) and Best Mode of carrying Out the Invention:

Referring now in greater detail to the drawings, Figure 1 illustrates a plunger clamp 10 in accordance with the present invention including a first support 12 having a first linear bearing 14 aligned with a second linear bearing 16 of a second support 18. An elongated plunger 20 is slidably held and supported within the two aligned bearings 14, 16, said plunge 20 having ends capable of receiving threaded adjustment knobs 17 to adjust the throw of said plunger clamp 10. A toggle lever 22 is pivotally connected to the top portion of the second support 18 at cross pin 24, the top portion forming a shoulder 26. The opposite end of the toggle lever 22 forms a handle 30 with a flange 32 integrally extending slightly upward from the handle. Cooperating between the plunger 20 and toggle lever 22 is a pair of locking arms 34 and 35 pivotally connected to the plunger 20 by a cross pin 36 and pivotally connected to the toggle lever 22 by a cross pin 40.
Flange 32 allows for convenient finger (or thumb) engagement to rotatably move the toggle lever 22 about cross pin 24 to actuate locking arm 34 which drives the plunger 20 along a longitudinal axis. With reference to Figures 4-6, said toggle lever 22 includes two lever arms 23 and 25 forming an opening through which the upper portions of the locking arms 34 and 35 extend as the toggle lever 22 is manipulated to the closed position. This cooperation allows the toggle lever 22 to be lowered toward the plunger 20 past the locking arms, establishing a plunger clamp apparatus with a low profile. The plunger 20 has a first concave detent 42 with an axis perpendicular to the longitudinal axis of the plunger which receives a portion of the cross pin 40 when the plunger is in the closed position, further increasing the locking force and increasing the downward travel of the toggle lever 22. Support 18 has a concave surface 43 with an axis perpendicular to the longitudinal axis of the plunger to permit full travel of the locking arms 34 and 35. In this position, the plunger 20 is locked in a push position.
Actuation of the toggle lever 22 about the axis of cross pin 24 from the first position (Figure 1) translates the axis of cross pin 40 from a point beneath the plane defined by the first axis and a third axis of the cross pins 36 and 24 through a path above and past a new plane defined by the axes of cross pins 36 and 24 in the second position as illustrated in Figure 2. The travel is reversed when the toggle lever is returned to the first position. Thus, the plunger generates a clamping force at each end of its stroke, and the linkage locks in an over-center position at each end of the stroke.
Figure 2 is the same view of the present invention as Figure 1 with the toggle lever 22 rotated about the first axis of cross pin 24 into the open position. In this position, the locking arm 34 rests on shoulder 26 of the second support 18 engaging the back 28 of the second support 18 to increase the locking force on the plunger 20.
Figure 3 illustrates the invention with a safety latch 46 pivotally connected to handle 30 with latch knob 48 engaging cross pin 36 to lock the plunger 20 in the closed position.
A second embodiment 11 of the invention is illustrated in Figures 7 and 8. The parts corresponding to the first embodiment share the same reference numeral with the addition of the prefix 1 . Thus, the plunger of Figure 1 (20) is labeled 120 in Figure 7. Figure 7 illustrates a pneumatic source having a cylinder 150 pivotally supported at cross pin 152 by side flange 154 affixed to a base 156, a piston rod 158 extending from the cylinder 150, and a rod end 160 integral to the piston rod 158. A triangular toggle link 162 is used in place of the toggle lever 22, but the operation is similar to the previous embodiment. The toggle link 162 is pivotally connected at all three corners to the piston rod end 160 at cross pin 164, to the locking arm 134 at cross pin 140, and to the second support 118 at cross pin 124. Upon actuating cylinder 150 to extend piston rod 158, engagement of rod end 160 with toggle link rotates the locking arm 134 past center to once again lock the plunger 120 in a close-push position. When the cylinder is retracted, the plunger 120 is returned to a closed position.
As illustrated in Figures 4 and 5, a base 56 is provided with three pairs of mounting holes strategically spaced so that either the present invention 10 may be secured to the base using bolts as shown, or a single support single-throw plunger clamp of the type of the prior art (not shown) may be affixed to said base using the same pair of mounting holes as the support 18 and the intermediate set of mounting holes.

Claims

A plunger clamp comprising:

at least one support;

an elongated plunger slidably held within said support;

at least one toggle lever pivotally mounted to said support at a first axis above said plunger;

at least one drive arm cooperating between said plunger and said toggle lever, said drive arm pivotally connected between said toggle lever and said plunger, said drive arm translating the angular motion of said toggle lever to drive said plunger along a longitudinal axis between first and second positions responsive to movement of said toggle lever.
The plunger clamp of claim 1, wherein said toggle lever rotates less than 180° between said first and second positions.
The plunger clamp of claim 1 or claim 2, wherein said toggle lever further comprises a flange opposite the pivoted end of said toggle lever easily accessed by hand in said first and second positions.
The plunger clamp of any one of the preceding claims, further comprising a means for safety locking said toggle lever in said closed position, said safety locking means comprises a safety latch pivotally connected to said toggle lever, said safety latch further comprising a cross pin pivotally connecting said drive arm and said plunger, said safety latch forms a lower portion beneath said pivot portion for releasably receiving said cross pin.
The plunger clamp of any one of the preceding claims, further comprising a cross pin pivotally connecting said toggle lever and said drive arm, said plunger having a concave detent receiving a portion of said cross pin when said toggle lever is in said closed position.
The plunger clamp of any one of the preceding claims, wherein said support shoulders said locking arm when said toggle arm is in the open position.
A plunger clamp comprising:

at least one support;

an elongated plunger slidably held within said support;

at least one drive arm pivotally mounted to said plunger at a first axis;

at least one toggle lever pivotally mounted to said support at a second axis above said plunger and pivotally connected to said drive arm at a third axis, such that said toggle lever rotates between a first clamping position wherein said third axis is located below the plane formed between said first and second axes, through a path where said third axis is above said plane to a second position.
The plunger clamp of claim 7, wherein said second position comprises a clamping position wherein said third axis is below said plane formed between said first and second axes, locking the plunger in said open position.
The plunger clamp of any one of the preceding claims, wherein said toggle lever includes a pair of spaced apart arms which form an opening through which said drive arm extends in said first position.
A plunger clamp comprising:

at least one support:

an elongated plunger slidably held within said support;

at least one drive arm pivotally mounted to said plunger at a first axis;

at least one triangular toggle link with one corner pivotally connected to said drive arm at a second axis, a second corner of said toggle link pivotally connected to said support at a third axis above said plunger;

a pneumatic drive cylinder including a reciprocating piston rod, said piston rod pivotally connected to a third corner of said toggle link, said piston rod when actuated causing said toggle arm to rotate about said third axis and said drive arm translating the angular motion of said toggle arm to drive said plunger along a longitudinal axis between a first and second position.
The plunger clamp of claim 10, wherein said toggle link rotates between said first position wherein said second axis is located below the plane formed between said first and third axes, through a path where said third axis is above said plane to second position.
The plunger clamp of any one of the preceding claims, wherein said plunger includes at least one threaded adjustment knob.
The plunger clamp of any one of the preceding claims, further comprising a second support aligned with first support wherein said plunger is slidably held within a pair of supports in the first and second positions.
The plunger clamp of claim 13, wherein said supports are machined from stainless steel.
The plunger clamp of any one of the preceding claims, wherein said plunger extends beyond said support for clamping in the direction of its motion in each the first and second position.