Claims
- 1. A hydraulically-operated linear impact device comprising
- a body member having a longitudinal bore extending therethrough and a plunger supported in said bore, main valve means, trigger valve means, hydraulic fluid lines connecting said bore and valves with a source of hydraulic fluid, spring means acting near the upper end of said plunger and means for detachably mounting a tool member at the lower end of said body member wherein
- a. said trigger valve means is mounted in said body member for movement between an actuating position and a rest position;
- b. said plunger is supported for reciprocating movement in said bore between a first position in which said plunger compresses the spring means at the upper end of the body member and a second position at the lower end of the body member in which said plunger may impact a tool member, and wherein said plunger has enlarged diameter area (DIA. 3) intermediate its upper and lower ends forming a valved annular work area (11) for hydraulic fluid pressure acting to move said plunger upward against said spring means;
- c. said main valve means having connections to said bore and to a high-pressure supply line and a lower-pressure return line for hydraulic fluid and being positionable, when the trigger is in actuating position, in response to a condition of said plunger such that when the plunger is in its downward second position said main valve means connects fluid under high pressure from said supply line to said valved annular area of the plunger to cause the plunger to be moved upward against said spring means, and when the plunger has moved to its upward, first position against said spring means, said main valve means connects said valved annular area to lower-pressure fluid such that said spring means is unopposed by high pressure and can then move said plunger downward on the impact stroke;
- d. said spring means comprises a mechanical, pneumatic or hydraulic spring which acts near the upper end of said plunger to bias the plunger downward, and wherein
- e. said hydraulic fluid lines are operable when the trigger is in the actuating position and said plunger is in its downward second position to provide a first fluid circuit from said high-pressure supply line to said main valve means for actuating the main valve means to connect fluid under high-pressure from said supply line to said valved annular area causing said plunger to be moved upward against said spring means and to compress said spring means, and
- said hydraulic fluid lines are operable when said plunger is in its upward first position to provide a second fluid circuit from said lower-pressure return line to said main valve means for actuating the main valve means to connect said valved annular surface to lower-pressure fluid causing the plunger to be moved downward to impact the tool member due to said compressed spring means acting on said plunger.
- 2. A hydraulically-operated linear impact device comprising
- a body member having a longitudinal bore extending therethrough (from an upper end to a lower end) and a plunger supported in said bore, main valve means, trigger valve means, hydraulic fluid lines connecting said bore and valve means with a source of hydraulic fluid, (hydraulic) spring means acting near the upper end of said plunger and means for detachably mounting a tool member at the lower end of said body member wherein
- a. said trigger valve means is mounted in said body member for movement between an actuating position and a rest position;
- b. said plunger is supported for reciprocating movement in said bore between a first position in which said plunger compresses the spring means at the upper end of the body member and a second position at the lower end of the body member in which said plunger may impact a tool member, and wherein said plunger has enlarged diameter areas (DIA. 2 and DIA. 3) intermediate its upper and lower ends forming a valved annular work area (11) for hydraulic fluid pressure acting to move said plunger upward against said spring means and a spring annular work area (16) for hydraulic fluid pressure acting to move said plunger downward to impact said tool member;
- c. said main valve means having connections to said bore, said trigger valve means and to a high-pressure supply line and a lower-pressure return line for hydraulic fluid and being positionable, when the trigger is in actuating position, in response to a condition of said plunger such that when the plunger is in its downward second position, said main valve means connects fluid under high-pressure from said supply line with said valved annular area of the plunger to cause the plunger to be moved upward against said spring means, and when the plunger has moved to its uppermost, first position against said spring means, said main valve means connects the valved annular surface to lower-pressure fluid such that said spring means is unopposed by high-pressure and can then move said plunger downward on the impact stroke;
- d. said hydraulic spring means comprises an enclosed volume at the upper end of the plunger bore which is filled with hydraulic fluid, sealed against fluid loss, and the fluid compressed by reducing the enclosed volume due to movement of the plunger upward within the enclosed volume to its first position, whereby the compressed fluid may act on the spring annular area; and wherein
- e. said hydraulic fluid lines are operable when the trigger is in the actuating position and said plunger is in its downward, second position to provide a first fluid circuit from said high-pressure supply line to said spring means for filling said enclosed volume and to said main valve means for actuating the main valve means to connect fluid under high-pressure from said supply line to the valved annular area causing said plunger to be moved upward against said spring means and to seal the enclosed volume and compress the hydraulic fluid in said enclosed volume of said spring means, and
- said hydraulic fluid lines are operable when said plunger is in its upward, first position to provide a second fluid circuit from said lower-pressure return line to said main valve means for actuating the main valve means to connect said valved annular surface to lower-pressure fluid causing the plunger to be moved downward to impact the tool member due to hydraulic fluid pressure in said spring means acting on said spring annular work area.
- 3. The impact device of claim 1 or 2 which further comprises pilot valve means for sensing the condition of said plunger and controlling the position of said main valve means wherein
- said pilot valve means is mounted for movement between first and second positions in response to a condition of said plunger such that when the trigger valve means is actuated and the plunger is in its downward second position said pilot valve means, in its second position, positions said main valve means to cause the plunger to be moved upward against the spring means, and when the plunger is in its upward, first position against said spring means said pilot valve means in its first position, positions said main valve means to allow the plunger to move in its downward impact stroke.
- 4. The impact device of claim 3 for striking single blows or continuous blows which further comprises a mode selector associated with said pilot valve means for allowing, in a first mode, continuous operation as provided in claim 3, and in a second mode, single blow operation wherein the mode selector comprises a means for selectively, temporarily holding said pilot valve means in its downward second position which upon actuation of said trigger valve means positions said main valve means to cause the plunger to be moved upward against said spring means, and when the trigger valve means is released to return to its unactuated position said pilot valve allows said main valve means to change positions and allow the plunger to move in its downward impact stroke.
- 5. The impact device of claim 1 or 2 in which flow and pressure in said return line are reduced during the impact stroke wherein
- said enlarged diameter area (DIA. 3) of said plunger also forms a return annular work area (10) opposed to said valved annular area, and
- said main valve means has connections to said bore and between said valved annular area and said return annular area such that when said plunger has moved to its upward, first position against said spring means said main valve connects the fluid under high pressure acting on said valved annular area to lower-pressure fluid acting on said return annular area.
Government Interests
The Government has rights in this invention pursuant to Contract No. N00024-75-C-4176 awarded by the U.S. Navy. Impact tools for tamping, breaking and cutting are known in the art and have been variously designed to employ three power systems--hydraulic, pneumatic and electric. The advantages of each are well reported and each suffers some disabilities.
US Referenced Citations (10)
Foreign Referenced Citations (3)
Number |
Date |
Country |
1209489 |
Oct 1970 |
GBX |
231478 |
Mar 1969 |
SUX |
481696 |
Apr 1978 |
SUX |