US3557663A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic drive system for injection molding machines
Assignee: Individual
•
Filing: 1968-07-29
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Granted: 1971-01-26
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Expires: 1988-07-29
Abstract
Abstract A device is provided for increasing the thrust force applied to a displaceable part at the end of its stroke. The part to be moved is connected by at least one push rod to a working piston, which is movable in a pressure chamber substantially without contacting the boundaries of said chamber. The piston is provided at one end with an annular sealing surface for engaging a valve piston, which is displaceable in the direction of the stroke of the working piston and is sealed at its periphery. The body of said valve piston has a bore between its rear end and its forward end, which is surrounded by the valve seat and faces the working piston. The chamber which adjoins the rear end is connected by a preferably valved outlet to a chamber which is under a pressure that is lower than the operating pressure.
Inventors
- 👤 Peter-Florjancic
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:23
CPC Classifications
B; B22; B22D; B22D17/00; B22D17/20; B22D17/26; Y; Y10; Y10S; Y10S425/00; Y10S425/223
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
192 words
A hydraulic drive system, particularly a closing device for an injection molding machine, the system comprising: a pressure chamber having walls closed by a cover; a pump system for feeding hydraulic fluid at the first pressure to said pressure chamber; a working piston movable in said pressure chamber without physical contact between the piston and the walls of said pressure chamber; a displacement member connected to said working piston by at least one pushrod, the pushrod passing through said cover; a valve piston displaceable in the working direction of the working piston and guided with its circumferential surface in sealed fashion in a valve space of the cover, said valve piston having at least one opening passing therethrough for connecting said pressure chamber with said valve space; a supply container for housing hydraulic fluid at a second pressure lower than said first pressure; sealing means on the respective facing surfaces of the working piston and the valve piston for closing said opening in the valve piston; and means for connecting said supply container to said valve space, the working piston and the valve piston thereby being acted on by the second pressure.
Claim 2
Dependent Claim
192 words
A hydraulic drive system, particularly a closing device for an injection molding machine, the system comprising: a pressure chamber having walls closed by a cover; a pump system for feeding hydraulic fluid at the first pressure to said pressure chamber; a working piston movable in said pressure chamber without physical contact between the piston and the walls of said pressure chamber; a displacement member connected to said working piston by at least one pushrod, the pushrod passing through said cover; a valve piston displaceable in the working direction of the working piston and guided with its circumferential surface in sealed fashion in a valve space of the cover, said valve piston having at least one opening passing therethrough for connecting said pressure chamber with said valve space; a supply container for housing hydraulic fluid at a second pressure lower than said first pressure; sealing means on the respective facing surfaces of the working piston and the valve piston for closing said opening in the valve piston; and means for connecting said supply container to said valve space, the working piston and the valve piston thereby being acted on by the second pressure.
Claim 3
Dependent Claim
45 words
A hydraulic drive system in accordance with claim 1, wherein said sealing means comprises a sealing ring arranged on the surface of the working piston facing the valve piston and a valve seat arranged on the surface of the valve piston facing the working piston.
Claim 4
Dependent Claim
39 words
A hydraulic drive system, according to claim 1, in which the valve piston is displaceably connected with a wall opposite said cover by means of a stop pin passing, in a sliding and sealed fashion, through the working piston.
Claim 5
Dependent Claim
79 words
A hydraulic drive system, according to claim 3, in which the valve piston contains a hydraulic chamber extending into the valve space; further comprising a stop pin extending, in a sealed fashion, through the end surface of the valve piston; a first passage opening in said valve piston defining a communication between said hydraulic chamber and the pressure sPace; and a second passage opening in said valve piston defining a communication between the hydraulic chamber and the valve space.
Claim 6
Dependent Claim
39 words
A hydraulic drive system, according to claim 4, and further comprising a nonreturn valve for closing the second passage opening in the hydraulic chamber against the return flow of hydraulic fluid from the valve space into the hydraulic chamber.
Claim 7
Dependent Claim
35 words
A hydraulic drive system, according to claim 3, in which the working piston is connected with the displacement member by means of two pushrods passed through openings in the end surface of the valve piston.
Claim 8
Dependent Claim
46 words
A hydraulic drive system, according to claim 6, in which the openings in the end surface of the valve piston are substantially larger in cross section than are the pushrods and therefore simultaneously serve as passage openings for connecting the valve space with the pressure space.
Claim 9
Dependent Claim
73 words
A hydraulic drive system, according to claim 1, in which, when the sealing means at the respective surfaces of the working piston and the valve piston rest in sealed manner against each other, the sum of all surfaces of the working piston exposed to the pressure in the pressure space in the direction of the displacement member, is greater than the sum of all surfaces of the working piston in the opposite direction.
Claim 10
Dependent Claim
35 words
A hydraulic drive system, according to claim 3, in which the valve piston is adjusted in its axial position by an adjusting screw provided through a wall of said pressure chamber remote from said cover.
Claim 11
Dependent Claim
24 words
A hydraulic drive system, according to claim 1, and further comprising return pistons guided laterally and outside the pressure space in separate hydraulic spaces.
Claim 12
Dependent Claim
44 words
A hydraulic drive system, according to claim 1, in which the end surface of the valve piston is surrounded by a rim protruding axially over the surface into which rim the sealing means on the working piston can be brought in a sealing fashion.
Claim 13
Dependent Claim
42 words
A hydraulic drive system, according to claim 11, in which the sealing means of the working piston are arranged on the circumferential surface of the working piston and cooperate with the inner surface of the axially protruding rim on the valve piston.
Claim 14
Dependent Claim
35 words
A hydraulic drive system, according to claim 3, in which the stop pin and the valve piston connected therewith are guided between two stops in the wall lying opposite the cover of the pressure space.
Claim 15
Dependent Claim
30 words
A hydraulic drive system, according to claim 1, in which the valve space is controllably connected with the space of lower pressure by means of a mechanically controlled solenoid valve.
Claim 16
Dependent Claim
30 words
A hydraulic drive system, according to claim 1, in which throttle openings are associated with the sealing means in order to delay the working piston before abutting the valve piston.
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) | 1974-01-25 | 1974-07-27 | 1975-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-25 | 1978-07-27 | 1979-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-25 | 1982-07-27 | 1983-01-26 | $7700.00 | Window Closed / Lapsed |