US2913876A - Hydraulic jack systems - Google Patents

Description

Nov. 24; 19579 K. E. REID l-mDRAuLIc JACK SYSTEMS Filed March 8. 1954 Y 434 7 L /TI 29 431,/ Y

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United States Patent() ice 2,913,876 HYDRAULIC JACK SYSTEMS Kenneth E. Reid, London, England, assigner to Smiths lacking Systems Limited, London, England, a British company Application March 8, 1954, Serial No. 414,818

Claims priority, application Great Britain March 9, 1953 z claims. (ci. 60-52) This invention relates to hydraulic apparatus of the kind having a plurality of hydraulic jacks, the supply of fluid to which is controlled by a number of valves. Hydraulic systems of this kind -are used for example to actuate hoods, windows, or other parts of motor-cars.

The main object of the invention is to provide such a system in which the minimum number of valves is required to control the jacks and in which any number of additional jacks can be included in the system together with the smallest additional number of valves.

According to the present invention there is provided a plurality of fluid pressure operated jacks, each jack having first and second pressure lines associated therewith through which actuating iluid may pass, for each jack an on-ol valve in one of the pressure lines associated therewith, a rst duct with which the ends of all the first lines remote from their associated jacks are in communication, a second duct with which the ends of all the second lines remote from their associated jacks are in communication, together with means to apply lluid pressures to said ducts, whereby when the on-oi valve associated with any jack is closed the jack is not actuated despite variations in uid pressure and if the on-o valve associated with any jack is open such jack is actuated in accordance with pressure variations at the ducts.

Preferably the jacks are of the kind having a piston and cylinder, the piston having different areas on different sides whereby the jack is actuated in one sense (e.g. eX- tended) by application of pressure to both sides of the piston and is actuated in the other sense (e.g. retracted) by application of pressure to the smaller side only, the larger side being connected to exhaust. If the rst lines are further defined as those connected to the ends of the cylinders appropriate to the smaller sides of the pistons, the first duct is always under pressure and the second duct is connected either to a pressure source or to exhaust. In a convenient arrangement pressure iluid is supplied by a motor-driven pump, drawing oil from a reservoir. The `delivery side of the pump is connected to the first duct, the irst duct to the second duct by a first main two-position valve and the second duct to the reservoir by a second main two-position valve. The delivery side of the pump is connected to the reservoir through a pressure relief valve, and the on-off valve associated with each jack is in the second duct.

Thus when the rst main valve is open and the second main valve is closed, any jacks, the on-oi valves for which are open, will be extended, while if the rst main valve is closed and the second main valve open the jacks for which the on-oif valves are open will be retracted.

It will thus be seen that the total number of valves required for n jacks is n-{2, while with prior art arrangements the number is at least 2n.

The invention will now be further described by way of example with reference to the accompanying diagrammatic drawing which is a layout of an hydraulic system made in accordance with the invention.

Jacks 10, 11 are for operating windows of a motor- Patented Nov. 24, 1959 car, jacks 12, 13 operate the hood. The jacks are of the kind having a piston and cylinder, the piston having different areas on opposite sides so that supply of uid pressure to both sides simultaneously actuates the jacks.

The jacks have pistons 14 connected to piston rods 114 each of which passes out through one end of the respective cylinder 115, this end being termed the annular end. An electric motor 15 drives a pump 16 which has an intake pipe 17 from a tank 18 and delivers liquid under pressure to a pipe 19 which is connected through a relief valve 20 to a return pipe 21 to the tank. Connections are provided from the pipe 19 direct (i.e. without passing through shut-oir control valves) to the small piston-area side of each of the jacks. Thus the pipe 19 is connected to a 'connecting joint 22 which is connected by pipes 23, 24, 25 to the jacks 12, 13 and by pipes 27, 28, 29` to the jacks 10, `11. Two normally open but closable valves 30, 31 are provided in hydraulic series between the pump outlet pipe 19 and the pipe 21. A third normally open but closable valve 32 is provided in series between the other ends vof the jacks 12, 13 and a connecting joint 33. This joint is disposed in pipe 34 which is connected between the valves 30, 31. A pipe 36 connects the joint 33 to the valve 32 and the latter is connected by pipes 40 to the jacks 12, 13.

'I'he jacks 10, 11 are associated with valves 42, 43 which are similar to valve 32, but one valve is provided for each jack 10, 11, so that they can be operated independently. Valves 42 and 43 are normally closed. The Valve 42 is connected by pipe 44 to the jack 10 at the large piston area, and by a pipe to a connecting joint 46. Similarly the valve 43 is connected by a pipe 48 to the jack 11 and by a pipe 49 to the joint 46. The latter is connected by a pipe to the joint 33.

Thus the pump delivery is connected to a rst duct constituted by the parts 22, 23, 27 which in turn are connected directly and permanently to the annular ends of the jack cylinders. A second duct constituted by the parts 33, 36, 50, are connected to the other ends of the jacks via on-oft` valves.

To extend either of Ithe jacks 10, 11, the valve 31 is closed, valve 30 is in its normally open position, and the valve 42 or 43 is opened. Jacks 12 and 13 are prevented from operating by closing valve 32. To retract the jacks 10 or 11 the valve 31 `is permitted to return to its normally open position while valve 30 is closed valve 42, or valve 43, as the case may be, being kept open. For operating the jacks 12, 13 without operating the jacks 10, 11, the valves 42, 43 are closed.

When the valves 30, 32 are open and the valve 31 is closed liquid pressure is delivered to both ends of the jacks 12, 13. The pistons are therefore forced in one direction (extending the jacks). To retract the jacks the valves 31, 32 are opened and the valve 30 is closed.

The Valves may all be actuated by solenoids controlled by a suitable electric circuit. Alternatively they may be constructed as described 4ancl illustrated in the specication of co-pending patent application No. 22,279 of 1951, now British Patent No. 711,975, published July 14, 1954.

As shown in the drawing, solenoids for each of the valves 30, 31, 32, 42 and 43 are indicated by numerals 30a, 31a, 32a, 42a and 43a, respectively, and are energized from a suitable D.C. supply with terminals indicated by and Ivia switches indicated by numerals 30h, 31b, 32b, 42h, and 43h, respectively.

I claim:

l. Hydraulic apparatus comprising a. plurality of liuid pressure operated jacks, each jack having rst and second pressure lines connected thereto through which actuating fluid may pass, for each jack an on-ofr valve in one of the pressure lines connected thereto, a first duct with which `the ends of all the rst lines away from their associated jacks are in communication, a second duct with which the ends of `all the second lines away from their associated jacks are `in communication, together with means to apply liuid pressures to said ducts and lines whereby when the onvoff Valve associated with any jack is closed the jack is` not actuated despite variations in fluid pressure and if the on-ot valve associated with any jack is open such jack is actuated in accordance with pressure variations in the ducts and lines, wherein saidmeans includes a pump, the delivery side of which is connected to the rst duct, the first duct is connected to the second duct by a first main valve, and the second duct is connected to exhaust by a second main valve, the delivery side of the pump being alsoy connected to the exhaust through a pressure relief valve, said jacks being of the kind having a piston and a cylinder, the piston having different areas on Adifferent .sides whereby the jack is actuated in one sensebyapplication -of pressure in'said pressure lines tol both sidesot` said piston, and is actuted in the other senseby `application of pressure to the smaller side only, thef larger side being connected to exhaust, said pump having an output opening connected permanently to the ends Vofthe cylinders containing the small ends of. the pistons.

2. Hydraulic apparatus as claimed inclaim 1 wherein at least one of the on-oif valves controls its correspond- `ing jack and simultaneously controls an additional jack, said valve being connected to the cylinders at the larger ends of the pistons.

References Cited in the tileof this patent UNITED STATES PATENTS

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