US3720484A

US3720484A - Hydraulic pressure transformer

Info

Publication number: US3720484A
Application number: US00120285A
Authority: US
Inventors: W Kirshsieper
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-03-04
Filing date: 1971-03-02
Publication date: 1973-03-13
Anticipated expiration: 1990-03-13
Also published as: GB1310645A; CH498302A; DE2109704A1

Abstract

A hydraulic pressure transformer for the delivery of liquid under high and low pressure comprising a first bore for control purposes with three pistons on a common piston rod and at least two concentric bores of different cross sections with two working pistons of different cross sections connected by a common piston rod. The bores are interconnected by passages to effect pressure transformation of the liquid.

Description

States atent m1 0 Kitten 3,720,484 Kirshsieper 51March 13, 1973 [54] HYDRAULIC PRESSURE 2,539,292 1/1951 Anderson ..417/225 SFORMER 2,826,149 3/1958 Wrigley 417/225 2,864,313 12/1958 Dawson ....417/225 [76] Inventor: Walter Kirshsieper, Urechmatt 121, 3,349,995 10/1967 Sheesley ..417/225 5445 Eggenwil, Switzerland Filed: March 1971 Przmary Exammer-Carlton R. Croyle Appl. No.: 120,285

Foreign Application Priority Data March 4, 1970 Switzerland ..3l42/70 References Cited UNITED STATES PATENTS 12/1874 Loretz ..417/225 Assistant Examiner-Richard Sher Att0rneyArnold Robinson [57] ABSTRACT A hydraulic pressure transformer for the delivery of liquid under high and low pressure comprising a first bore for control purposes with three pistons on a common piston rod and at least two concentric bores of different cross sections with two working pistons of different cross sections connected by a common piston rod. The bores are interconnected by passages to effect pressure transformation of the liquid.

1 Claim, 1 Drawing Figure HYDRAULIC PRESSURE TRANSFORMER This invention relates to a hydraulic pressure transformer for raising the pressure of a working fluid and able to deliver the same at low pressure as well as high pressure.

There are hydraulically powered machines, such as stamping and deep-drawing presses, which require a high pressure in the hydraulic drive for the working stroke and a low pressure for tool withdrawal possibly with rapid travel.

The pressure transformer according to the invention has for its object to generate both these pressures.

The hydraulic pressure transformer of this invention comprises a housing with passages for the inlet and outlet of a liquid working medium under pressure and for delivery of same at low-pressure as well as at high-pressure; a first bore for a control slide with three separate pistons arranged on a common piston rod at intervals from each other, and at least two concentric bores for at least two working pistons of different cross sections connected with each other; a first passage into the space between the first and second or second and third pistons of the control slide, for supplying working fluid, a first duct from said intermediate space to the free end of the first working pistons; a second passage from the space between the first and second pistons of the control slide to the outside for delivering the working piston into the space between the first and second pistons of the control slide, a third duct leading from the space at the free end of the third piston of the control slide into the bore for the second working piston, a fourth duct leading from the space between the working pistons to the space behind the free end of the first piston of the control slide, and third passage for delivery of the working fluid under increased pressure through the bore for the first working piston, the first duct and the first bore to the outside, whereby the second and third pistons of the control slide alternately open and close the second and third passages upon displacement of the control slide, and the second working piston uncovers or blocks the opening of the third duct in its bore and the first piston uncovers or blocks the opening of the fourth duct in its bores.

The accompanying drawing shows a diagrammatic sectional view of a preferred form of embodiment of the hydraulic pressure transformer.

In said annexed drawing the hydraulic pressure transformer shown comprises a housing 1 with a bore 2, in which

pistons

4, 5 and 6 linked with a piston rod 3 are displaceably fitted. Said pistons act as control elements for the pressure transformer.

A bore 7 in housing 1 has displaceably arranged therein a low-pressure piston 8, and a bore 9 concentric with bore 7 a high-pressure piston 10. Pistons 8 and 10 are connected by a piston rod 1 1.

Three

passages

12, 13 and 14 lead out from the bore 2. A duct 15 connects the bore 9 with the space to the left of piston 4 in the bore 2. The space to the right of piston 6 communicates via a duct 16 with bore 7, between pistons 8 and 10. The opposite ends of bores 7 and 9 communicate via ducts l7 and 18 with the spaces of bore 2 between pistons 4, .5 and 5, 6 respectively. Finally from the spaces of bores 7 and 9 a duct 19 leads out between the pistons 8 and l0.

The pressure transformer described is connected through the passage 12 with a source supplying liquid (working fluid) under low pressure, say, from a lowpressure pump.

In the starting position shown, the working fluid enters the bore 2, whence it passes via duct 18 into the space behind the high-pressure piston 10 on the right. The same is forced (to the left in the drawing) by the working fluid, moving the low-pressure piston 8 in the same direction through piston rod 11. The fluid remaining in bore 7 is ejected through duct 17 and passage 13 by this movement of piston 8. Passage 14 is blocked by piston 6.

As soon as the piston 10 uncovers the duct 15 leadinginto bore 9, the working fluid flows through duct 15 into the space on the left behind piston 4, pushing same to the right together with

pistons

5 and 6. The fluid on the right in the space behind piston 6 passes through duct 16 into bore 7. A duct 19 allows leakage fluid to escape outside.

Upon displacement of

pistons

4, 5 and 6, piston 4 blocks the passage 13 and piston 6 opens the way for the fluid in bore 9 to the passage 14. The working fluid then flows from passage 12 through duct 17 into the space on the left behind piston 8, moving same to the right together with piston 10. As a result, a pressure is established in bore 9 as determined by the pressure of the low-pressure pump and the ratio between the cross sections of pistons 8 and 10. The working fluid now under higher pressure is forced to the working point through passage 14.

As soon as this movement of piston 8 uncovers the opening of duct 16 into bore 7, the working fluid passes through duct 16 into the space on the right behind piston 6, pushing same to the left together with

pistons

4 and 5. The fluid in the space to the left of piston 4 runs off through duct 15 and duct 19.

The parts of the pressure transformer are now again back in their starting positions according to the drawing, and the aforedescribed cycle is repeated.

ln this way the pressure transformer allows consecutive pressure pulses to be delivered, with alternately higher and lower pressure.

Thus for example on hydraulically powered deepdrawing and stamping presses the high-pressure pulse from the passage 14 can be used for the working stroke of the press, while the rapid return of the press tool is brought about with the low-pressure pulse from passage 13, or else a control valve may be needed in advance of the pressure transformer to switch it over when the maximum pressure of the low-pressure pump is reached.

Alternatively a number of pistons 8 and 10 may be arranged in parallel to reduce the pulsating pressure delivered.

The pressure transformer starts in any position.

By arranging a pressure limiting means, such as a spring, between pistons 8 and 10, and making these displaceable in relation to each other, a pressure limitation may be obtained. With the maximum admissible pressure reached by the high-pressure piston, piston 10 comes to a stop, whilst the low-pressure piston 8 will be displaced further against the action of the limiting means, until the opening of duct 16 isvuncovered thus causing the pressure transformer to be switched over.

Piston 10 then returns to its particular starting position. At the next reversal of

pistons

4, 5 and 6 (control pistons) the high-pressure piston 10 only covers the pressure drop caused by the leakage losses. As long as working fluid is required at the same pressure, this mode of operation will be repeated by the pressure transformer thus designed. With pressure relieved below the switch-over pressure, the pressure transformer ceases to operate.

What I claim is:

l. A hydraulic pressure transformer, having a housing with passages for the inlet ofa liquid working medium under pressure and for delivery of same at low pressure as well as at high pressure; a first bore having a control slide therein with three separate pistons arranged on a common piston rod at intervals from each other, and at least two connecting concentric bores of different cross sections with at least one working piston in each said concentric bore, said working pistons each being adapted to make a sliding engagement with its respective bore, said working pistons being connected with each other by a common piston rod of cross section smaller than that of either of said bores; a first passage opening alternatively into the space between the first and second pistons and between the second and third pistons of the control slide, for supplying working fluid, a first duct connecting said space between the second and third piston to the space behind the free end of the first working piston; a second passage connecting the space between the first and second pistons of the control slide to the outside for delivering the working fluid under low pressure, a second duct extending from the free end of the second working piston into the space between the first and second pistons of the control slide, a third duct leading from the space at the free end of the third piston of the control slide into the bore for the second working piston, a fourth duct leading from the space behind the free end of the first piston of the control slide into the bore for the first working piston, a third passage for delivery of the working fluid under increase pressure from the bore for the first working piston through the first duct and the first bore to the outside, and a vent passage connecting the said concentric bores with the outside and having its opening to the bores located between the openings of said third and fourth ducts, whereby the first and third pistons of the control slide alternately open and close the second and third passages respectively upon displacement of the control slide, and the second working piston alternately communicates the opening of the third duct in its bore with the space behind the free end of the second working piston and the opening of the vent passage; and the first working piston alternately communicates the opening of the fourth duct in its bore with the space behind the free end of the first working piston and the opening of the vent passage.

Claims

1. A hydraulic pRessure transformer, having a housing with passages for the inlet of a liquid working medium under pressure and for delivery of same at low pressure as well as at high pressure; a first bore having a control slide therein with three separate pistons arranged on a common piston rod at intervals from each other, and at least two connecting concentric bores of different cross sections with at least one working piston in each said concentric bore, said working pistons each being adapted to make a sliding engagement with its respective bore, said working pistons being connected with each other by a common piston rod of cross section smaller than that of either of said bores; a first passage opening alternatively into the space between the first and second pistons and between the second and third pistons of the control slide, for supplying working fluid, a first duct connecting said space between the second and third piston to the space behind the free end of the first working piston; a second passage connecting the space between the first and second pistons of the control slide to the outside for delivering the working fluid under low pressure, a second duct extending from the free end of the second working piston into the space between the first and second pistons of the control slide, a third duct leading from the space at the free end of the third piston of the control slide into the bore for the second working piston, a fourth duct leading from the space behind the free end of the first piston of the control slide into the bore for the first working piston, a third passage for delivery of the working fluid under increase pressure from the bore for the first working piston through the first duct and the first bore to the outside, and a vent passage connecting the said concentric bores with the outside and having its opening to the bores located between the openings of said third and fourth ducts, whereby the first and third pistons of the control slide alternately open and close the second and third passages respectively upon displacement of the control slide, and the second working piston alternately communicates the opening of the third duct in its bore with the space behind the free end of the second working piston and the opening of the vent passage; and the first working piston alternately communicates the opening of the fourth duct in its bore with the space behind the free end of the first working piston and the opening of the vent passage.