US3878902A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impact tool
Assignee: Individual
•
Filing: 1973-03-22
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Granted: 1975-04-22
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Expires: 1993-03-22
Abstract
Abstract Disclosed is a free-piston type, pneumatically operated impact tool comprising a tool cylinder and a pump cylinder both pneumatically and integrally connected. The reciprocation of the pump piston in the pump cylinder will cause the massive freepiston to rise and descend in the tool cylinder, and the freepiston will hammer the shank of the chisel at the end of the down stroke. The unique design of the pneumatic connection between the top spaces of the tool and pump pistons permits the use of a heavier free-piston, and hence the impact power will be accordingly increased.
Inventors
- 👤 Susumu Matsuo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:56
CPC Classifications
B; B25; B25D; B25D11/00; B25D11/06; B25D11/12; B25D11/125
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
219 words
A pneumatic impact tool comprising in combination: A. an air pump cylinder having a pump piston slidably disposed therein, and crank mechanism means for slidably moving said pump piston; B. a tool cylinder having a free-piston slidably disposed therein, said tool cylinder having an aperture on the head portion thereof and a unidirectional port means which allows air to pass from said tool cylinder to said pump cylinder through said upper tube housing, but prevents air from otherwise passing, said free-piston having a male member disposed to pneumatically close the aperture; C. an upper tube housing pneumatically connecting the upper portion of the air pump cylinder and, the aperture and unidirectional exhaust port of the tool cylinder; D. a common side wall opening joining the lower portion of the air pump cylinder and the lower portion of the tool cylinder said opening having a height less than the height of the freepiston and disposed to permit a free pneumatic opening when the free-piston is at the bottom dead point within the tool cylinder; and E. a chisel slidably mounted into the bottom of said tool cylinder and protruding therefrom, said chisel contacting the free-piston and movable thereagainst for placing the freepiston in position to pneumatically seal said common side wall opening whereby pneumatic movement of the free-piston is initiated.
Claim 2
Dependent Claim
219 words
A pneumatic impact tool comprising in combination: A. an air pump cylinder having a pump piston slidably disposed therein, and crank mechanism means for slidably moving said pump piston; B. a tool cylinder having a free-piston slidably disposed therein, said tool cylinder having an aperture on the head portion thereof and a unidirectional port means which allows air to pass from said tool cylinder to said pump cylinder through said upper tube housing, but prevents air from otherwise passing, said free-piston having a male member disposed to pneumatically close the aperture; C. an upper tube housing pneumatically connecting the upper portion of the air pump cylinder and, the aperture and unidirectional exhaust port of the tool cylinder; D. a common side wall opening joining the lower portion of the air pump cylinder and the lower portion of the tool cylinder said opening having a height less than the height of the freepiston and disposed to permit a free pneumatic opening when the free-piston is at the bottom dead point within the tool cylinder; and E. a chisel slidably mounted into the bottom of said tool cylinder and protruding therefrom, said chisel contacting the free-piston and movable thereagainst for placing the freepiston in position to pneumatically seal said common side wall opening whereby pneumatic movement of the free-piston is initiated.
Claim 3
Dependent Claim
219 words
A pneumatic impact tool comprising in combination: A. an air pump cylinder having a pump piston slidably disposed therein, and crank mechanism means for slidably moving said pump piston; B. a tool cylinder having a free-piston slidably disposed therein, said tool cylinder having an aperture on the head portion thereof and a unidirectional port means which allows air to pass from said tool cylinder to said pump cylinder through said upper tube housing, but prevents air from otherwise passing, said free-piston having a male member disposed to pneumatically close the aperture; C. an upper tube housing pneumatically connecting the upper portion of the air pump cylinder and, the aperture and unidirectional exhaust port of the tool cylinder; D. a common side wall opening joining the lower portion of the air pump cylinder and the lower portion of the tool cylinder said opening having a height less than the height of the free-piston and disposed to permit a free pneumatic opening when the free-piston is at the bottom dead point within the tool cylinder; and E. a chisel slidably mounted into the bottom of said tool cylinder and protruding therefrom, said chisel contacting the free-piston and movable thereagainst for placing the free-piston in position to pneumatically seal said common side wall opening whereby pneumatic movement of the free-piston is initiated.
Claim 4
Dependent Claim
219 words
A pneumatic impact tool comprising in combination: A. an air pump cylinder having a pump piston slidably disposed therein, and crank mechanism means for slidably moving said pump piston; B. a tool cylinder having a free-piston slidably disposed therein, said tool cylinder having an aperture on the head portion thereof and a unidirectional port means which allows air to pass from said tool cylinder to said pump cylinder through said upper tube housing, but prevents air from otherwise passing, said free-piston having a male member disposed to pneumatically close the aperture; C. an upper tube housing pneumatically connecting the upper portion of the air pump cylinder and, the aperture and unidirectional exhaust port of the tool cylinder; D. a common side wall opening joining the lower portion of the air pump cylinder and the lower portion of the tool cylinder said opening having a height less than the height of the free-piston and disposed to permit a free pneumatic opening when the free-piston is at the bottom dead point within the tool cylinder; and E. a chisel slidably mounted into the bottom of said tool cylinder and protruding therefrom, said chisel contacting the free-piston and movable thereagainst for placing the free-piston in position to pneumatically seal said common side wall opening whereby pneumatic movement of the free-piston is initiated.
Claim 5
Dependent Claim
26 words
A pneumatic tool according to claim 1 wherein said unidirectional exhaust port comprises an aperture to communicate with said upper tube housing and a non-return valve.
Claim 6
Dependent Claim
66 words
A pneumatic impact tool according to claim 1 wherein said common side wall opening is open at the top thereof when the free-piston reaches the bottom dead point and is closed when the free-piston is elevated by the chisel, the pump piston being permitted to slidably operate in idle state when the free-piston is at the bottom dead point without effecting pneumatic movement of the free-piston.
Claim 7
Dependent Claim
34 words
A pneumatic impact tool according to claim 1 wherein the bottom surface of said free-piston has a counter sunk recess to accomodate the end of said chisel when said free-piston strikes against said chisel.
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) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |