The invention relates to fluid operated devices such as hand tools and, more particularly, to a gripping tool such as locking pliers.
Conventional locking pliers such as the Vise-Grip® pliers having a mechanical system that once tripped, allows the pliers to stay latched on to the work that it has grasped. However, it takes substantial hand strength to set the conventional locking pliers and even more strength to release its hold on the work.
There is a need to provide a hydraulically powered hand tool that requires a relatively low input force, provides significant output force, and that is easy to disengage from the work.
An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is achieved providing a hydraulically operated tool including a body, a trigger mounted for movement between first and second positions with respect to the body, a pair of jaws mounted with respect to the body so that at least one of the jaws is movable between an opened jaw position and a closed jaw position so as to engage work between the jaws, jaw actuating structure associated with the jaws to cause movement of the at least one jaw, a ram assembly having first and second ends and including a valve actuating structure and a ram piston, the valve actuating structure having first and second ends, the first end of the ram assembly being coupled with the jaw actuating structure, a first check valve associated with the ram piston, a second check valve associated with the ram piston and with the second end of the valve actuating structure, a lever associated with the first end of the valve actuating structure and with the ram assembly, surfaces defining a cavity in the body, the cavity having hydraulic fluid therein, the ram piston being disposed in the cavity separating the cavity to define a ram chamber and a reservoir chamber, spring structure engaging a second end of the ram assembly, and a pump assembly operatively associated with the trigger to be movable between a first position, when the trigger is in the first position, and a second position when the trigger is in a second position, the pump assembly having a pump chamber in selective fluid communication with the ram chamber and the reservoir chamber. When the lever is moved to an activated position, the valve actuating structure unseats the second check valve permitting fluid to flow from the ram chamber to the reservoir chamber, with the ram assembly displacing fluid as it compresses the spring structure and causes the jaw actuating structure to move the at least one jaw so work can be placed between the jaws. When the lever is released from the activated position, the second check valve is seated and the spring structure drives the ram assembly to an extended position causing the jaw actuating structure to move the at least one jaw so the jaws engage the work, with the first check valve being unseated by fluid pressure in the reservoir chamber, permitting fluid to flow from the reservoir chamber to the ram chamber. When the trigger is moved from the first position to the second position, the pump assembly moves to the second position thereof and forces fluid from the pump chamber into the ram chamber causing the first check valve to seat, with the forced fluid being exerted on the ram piston, increasing force of the jaws on the work.
In accordance with another aspect of the invention, a method of applying force to workpiece provides a hydraulic tool having a pair of jaws constructed and arranged to receive the workpiece there-between. The tool includes a ram assembly operatively associated with the jaws. The ram assembly is caused to move thereby causing the jaws to initially engage the workpiece with a first force. Fluid is exerted on the ram assembly to move the ram assembly further, causing the jaws to exert a second force, greater than the first force, on the workpiece.
Other objects, features, functionality and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.
The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawing, in which:
With reference to
The tool 20 has a main body B and a trigger 14 mounted for movement between opened and closed positions with respect to the body B. Links 22 (one shown in
Starting from the jaw-closed position and with no positive pressure in ram chamber R, the jaws 21 are opened and fluid is redistributed by manually moving to the right in
Simultaneously as unseating of check valve 12 due to moving the slider 13 and lever 11 to the right as noted above, the gear rack 3 rotates the gear segments 4 and 4′, opening at least one of the jaws 21.
The jaws 21 of the tool 20 are then placed around the work W (
The ram piston 9 moves through the fluid as the spring structure 1 pushes it forward (towards the left in
With the jaws grasping the work, a second mode of action applies additional force on the jaws 21 by actuating trigger 14. Note that this trigger 14 is free to move independently of gear segments 4 and 4′ because of the slot 23. Prior to squeezing the trigger, the pump assembly 7 pulls fluid from the reservoir chamber P via port 24 through the check valve 16 to provide maximum volume in pump chamber 26 (
Thus, the ram assembly 2 in the tool 20 has two forward speeds. By using a ram assembly 2 with the O-ring 5, the internal spring structure 1 can drive the ram assembly 2 forward at a higher speed than the pump assembly 7 will.
To again open the jaws 21 and rest the tool 20, the pressure on the ram assembly 2 is released by letting the fluid flow through the ram piston 9. As noted above, this is done with the push rod 10 that extends through a rod portion of the ram assembly 2. The lever 11 or a cam acts on the push rod 10 at the distal end of the push rod 10 proximal to the rack gear 3. At the other end of the push rod or ram end, the push rod 10 bears against the check valve (e.g., ball) 12 in the center of the ram piston 9. The check valve 12 is opened when a force is exerted on the push rod 10 by the lever 11, permitting fluid to move from ram chamber R to reservoir chamber P.
The slider 13 associated with, or part of, the lever 11 is accessible to manually apply the force to actuate the push rod 10. As noted above, the same force also moves the rack 3, retracts the ram assembly 2, cocking the spring 1, and opening the jaws 21.
The link 22 retracts the pump assembly 7 (moves to the right in
The enlarged view (
The spring structure 1 preferably includes two constant rate compression springs 1′ and 1″. In the embodiment, the springs 1 and 1″ are placed base-to-base.
The gear rack 3 is supported on the top with rollers 29 between the gear rack 3 and the body B that are limited in travel. It is apparent that the rollers 29 will travel half the distance that the rack 3 travels, and will be kept in alignment by ends of a slot 35 containing each roller 29.
The check valves 8 and 16 are also of the type described in incorporated U.S. Pat. No. 6,341,621.
The tool 20 includes the following functional features:
The tool 20 has been shown with jaws 21 configured as locking pliers for clamping but, it can be appreciated that the jaws 21 can be configured for crimping, cutting, bending, punching, etc.
With the tool 20, a 22-pound squeeze of the trigger can deliver about forty-five times (e.g., about 1000 pounds) clamping force on the jaws 21 due to the internal hydraulics. Furthermore, simply moving the slider 13 releases the grasp of the jaws 21. For some idea of relative strengths, a man's grip averages 50 pounds, and a woman's grip averages 30 pounds.
Although the embodiment shows a hand tool, it can be appreciated that the tool can be configured for other applications that are not manually operated.
The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.
This application is based on U.S. Provisional Application No. 60/670,698, filed on Apr. 13, 2005 and claims the benefit thereof for priority purposes.
Number | Name | Date | Kind |
---|---|---|---|
2208058 | Smith | Jul 1940 | A |
2224708 | Van Sittert | Dec 1940 | A |
2487281 | Steckelberg | Nov 1949 | A |
4351097 | Hashimoto et al. | Sep 1982 | A |
4475374 | Sakai et al. | Oct 1984 | A |
5806362 | Dubugnon | Sep 1998 | A |
6415641 | Wagner | Jul 2002 | B1 |
Number | Date | Country | |
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20060230810 A1 | Oct 2006 | US |
Number | Date | Country | |
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60670698 | Apr 2005 | US |