US3872934A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impact tool
Assignee: Nippon Pneumatic Manufacturing Co Ltd
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Filing: 1973-10-30
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Granted: 1975-03-25
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Expires: 1993-10-30
Abstract
Abstract An impact tool operated by high pressure fluid has a main piston fitted into a main cylinder, the upper chamber of the main cylinder being filled with gas of predetermined pressure. A liquid chamber for containing liquid for pressing the main piston upward by liquid pressure is provided between the lower half of the main piston and the main cylinder. A limit valve is provided in the upper part of the main cylinder, the limit valve being activated when the main piston is elevated adjacent to the upper limit thereof so that the liquid pressure source and the liquid chamber within the main cylinder are disconnected from each other by valve means provided on one side of the main cylinder activated by the gas pressure in the upper chamber of the main cylinder and the liquid chamber is placed in communication with the liquid outlet. On the lower end of the main cylinder is fitted a tool, such as a chisel and the like, which is struck by the main piston when the main piston is driven down by the gas compressed in the upper part of the main cylinder by the raising of the main piston.
Inventors
- 👤 Hiromu Terada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 03:02
CPC Classifications
B; B25; B25D; B25D9/00; B25D9/14; B25D9/145; Y; Y10; Y10S; Y10S173/00; Y10S173/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
377 words
In an impact motive implement having a main cylinder having a larger diameter upper portion and a smaller diameter lower portion, a main piston in said main cylinder having a larger diameter upper portion slidable in the upper portion of the cylinder and a smaller diameter lower portion slidable in the lower portion of the main cylinder, a tool holder on the lower end of said main cylinder and an impact tool mounted in said tool holder and against the upper end of which the lower end of the lower piston portion strikes when the main piston is lowered, said main cylinder having a liquid port opening into said lower portion of said main cylinder at a point below said lower portion of said main piston when said main piston is in the lowermost position in said main cylinder, a valve casing on said main cylinder having a liquid port communication with said liquid port in said main cylinder and further having a liquid inlet port and a liquid outlet port, a compressed gas operated main valve slidable in said valve casing between a first position in which it blocks off communication between said liquid port communicating with said main cylinder and said liquid inlet port and a second position in which it blocks off communication between said liquid port communicating with said main cylinder and said liquid outlet port, said main cylinder having a passage therethrough from said upper portion of said main cylinder to a position of said valve casing for supplying compressed gas thereto for actuating said main valve for moving it to said first position, limIting valve means in said passage and engageable by the upper portion of said main piston near the upper limit of its movement for opening said limiting valve means, and a source of compressed gas connected to said valve casing for supplying compressed gas for urging said main valve toward said second position, the improvement comprising a subsidiary valve body, said main valve having a recess therein exposed to the space within said valve casing through which the liquid flows from the main cylinder to said outlet port, said subsidiary valve body being slidable in said recess in response to overpressure in said space to relieve said overpressure.
Claim 2
Dependent Claim
377 words
In an impact motive implement having a main cylinder having a larger diameter upper portion and a smaller diameter lower portion, a main piston in said main cylinder having a larger diameter upper portion slidable in the upper portion of the cylinder and a smaller diameter lower portion slidable in the lower portion of the main cylinder, a tool holder on the lower end of said main cylinder and an impact tool mounted in said tool holder and against the upper end of which the lower end of the lower piston portion strikes when the main piston is lowered, said main cylinder having a liquid port opening into said lower portion of said main cylinder at a point below said lower portion of said main piston when said main piston is in the lowermost position in said main cylinder, a valve casing on said main cylinder having a liquid port communication with said liquid port in said main cylinder and further having a liquid inlet port and a liquid outlet port, a compressed gas operated main valve slidable in said valve casing between a first position in which it blocks off communication between said liquid port communicating with said main cylinder and said liquid inlet port and a second position in which it blocks off communication between said liquid port communicating with said main cylinder and said liquid outlet port, said main cylinder having a passage therethrough from said upper portion of said main cylinder to a position of said valve casing for supplying compressed gas thereto for actuating said main valve for moving it to said first position, limIting valve means in said passage and engageable by the upper portion of said main piston near the upper limit of its movement for opening said limiting valve means, and a source of compressed gas connected to said valve casing for supplying compressed gas for urging said main valve toward said second position, the improvement comprising a subsidiary valve body, said main valve having a recess therein exposed to the space within said valve casing through which the liquid flows from the main cylinder to said outlet port, said subsidiary valve body being slidable in said recess in response to overpressure in said space to relieve said overpressure.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |