US3087307A

US3087307A - Hydraulic circuits

Info

Publication number: US3087307A
Authority: US
Inventors: Faisandier Jacques
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-06-21
Filing date: 1961-06-05
Publication date: 1963-04-30
Anticipated expiration: 1980-04-30

Description

J. FAISANDIER 3,087,307

HYDRAULIC CIRCUITS April 30, 1963 Filed June 5, 1961 2 Sheets-Sheet 1 A ril 30, 1963 J. FAISANDIER 3,087,307

HYDRAULIC CIRCUITS Filed June 5, 1961 2 Sheets-Sheet 2 United States Patent Ofiiice dfifiLBfl-T Patented Apr. 30, 1953 3,0875%? HYDRAULEC QERCUZTE; Eacques Faisandier, 32 Blvd. Felix Faure, tlhatiilon-sous-Eagneux, France Filled dune 5, 1961, Ser. No. 1i4,97 Ciaims priority, application France dune 21, 1366 6 tClai-ms. (Cl. 6---9'7) The invention relates to hydraulic circuits, and in particular to high pressure hydraulic circuits with multiple hydraulic jacks.

For certain purposes, it may be desirable not to leave the general circuit at high pressure, and in particular not to let the pump supply the circuit at high pressure, especially when it is used with interruptions of greater or less duration.

The pro lem has already been solved by the use of decompression valves which automatically reduce the pressure in the circuit as soon as no receiver elements are connected to the circuit and all the distributor elements are in the neutral position.

However, to reestablish anew the high pressure level in the circuit requires a special operation, generally to obtain momentary decompression which moves the decompression valve into the operating position.

The object of the invention is to render this operation automatic, so that it will respond to each of the distributors individually. On the one hand, greater simplicity and rapidity of the operation is achieved, and on the other hand the system of pipes is greatly simplified.

With this object in view, the invention comprises a device adjacent to the control of each distributor so that the latter, which normally have their centres closed, momentarily have their centres open.

Below will be given by way of example, an embodiment of the invention, although the general scope of the invention is in no way limited to the particular features or by the specific features of the example chosen as illustration.

In the attached drawings:

FIGURE 1 is a general plan of the hydraulic circuit of the invention.

FIGURES 2 and 3 are respectively partial views of two different embodiments; the parts which are similar to those in FIGURE 1 have not been shown again.

The described installation may comprise any number of receiver elements 1, each of which is controlled by a distributor 2. The distributors are connected in parallel between the general feed circuit 3 and the general return circuit 4 at the tank 5. For the sake of clarity, only a single group comprising a receiver 1 with distributor 2 has been shown. The other groups are identical to it or of the same type. The general circuit, which is shown open at 6 and '7, is in fact closed by the distributor or distributors not shown, and all circulation of fluid is interrupted in the general circuit when all the distributors are set to neutral, by definition even of the distributors with closed centre. The general circuit is supplied by the pump 8 through the usual non-return valve 9. Connected to the high pressure duct 3 of the general circuit is the decompression valve 16, including a valve distributor the piston 12 of which is under the action of the spring 213. The movement of the piston 12 against the action of the spring 13 is limited, in this case by the stop 14. The centre of the distributor is closed. The pump pressure acts on the centre through the inlet 15 and the pressure of the general circuit acts at 16 on the piston, at the end opposite to that at which the spring 13 acts. An auxi-liary circuit 17 returns fluid to the cistern 5. The three chambers formed by lands of piston 12 are connected with 17 through the outlets 18, 19' and 2d. The

outlets

18 and 19 establish a permanent communication with 17 but 29 is normally closed and opens only when the piston moves to the left. The

outlets

19 and 20 are limited by a throttle 21 which is shunted by the calibrated valve 22..

The distributor 2 comprises a double slide valve having lands 23, 24 forming the usual distributor slide valve properly speaking for the receiver 1, whereas the elements 25, 2s constitute the lands of an auxiliary slide valve the function of which is to connect the centre of the first slide valve, which is normally closed, momentarily with the cistern whereby a momentary drop in pressure is caused in the supply circuit to actuate valve 12. For this purpose, the slide valve assembly is hollow and forms a closed chamber which is permanently in communication with the general circuit through the pipe system 37 and the apertures 2'7 and the median chamber between the

elements

28, 24, and with the cistern by means of the pipe system 34 and the

apertures

28, 29 which are normally closed but are open as soon as the slide valve is slightly displaced from the neutral position and are closed again as soon as this movement increases. The nonoperating chambers of the double slide valve are permanently in communication with the cistern through the

apertures

39, 31, 32, 33 and the system of pipes 34.

The double slide valve assembly is controlled by the lever 35 which is hinged at 38, with a pivot at 39, and the conventional spring not represented is provided to return the slide valve into the neutral position.

If all distributors are out of service their slide valves will be in the neutral position, and there will be no further flow through the circuit 3, so that the pressure will rise at 16 and push the piston to the left against the action of the spring 13. For the sake of illustration, it will be supposed that this pressure is 250 kg./cm.

On moving to the left, the slide valve opens the aperture 2th so that oil can flow towards 19, which increases the thrust to the left but at the same time permits flow across the aperture of the throttle 21 and the calibrated valve 22.

Supposing the combined action out 21 and 22 produce a pressure of 40 kg./cm. on the upstream side of 21 and 22 and that the useful cross section S is 7 times that of S the piston will move to its left stop 14 and the whole circuit will be under a pressure of 40' kg/cm at which there is no strain on any of the structural elements, even if it is maintained permanently.

In order to put one of the hydraulic jacks into operation, it is necessary to raise the pressure of the general circuit 3 again, which is effected automatically by the invention as soon as one of the hydraulic jacks is actuated in one sense or another by its control 35 that is as soon as one of the

apertures

28 or 29 puts the median chamber or" the distributor 2 into communication with the cistern 5.

At that moment, the pressure in the general circuit will fall from 40 kg./cn1. to 25 lag/cm for example the piston of valve 12 will move to the right under the action of the spring 13, closing 2% and thus cutting off the pump from the cistern, and the pressure in 19 will fall. The pressure may then be raised again to 250 kg/cm. in the general circuit without disturbing the equilibrium of the piston of the slide valve 12. The stopping of the double slide valve of the distributor 2 in the positions with open centre is only momentary. These positions may be marked by a catch stop to allow the pressure to descend to 25 kg./cm. before the control movement pursues. The control for releasing the catch, which is not shown, which immobilises the control, may be manual, or automatic by hydraulic means, the releasing movement taking place as soon as the pressure in the general circuit has dropped to 25 kg./cm.

As soon as the slide valve of the distributor 2 has passed the bypass position, the centre of the distributor is closed again, and the distributor again operates in the usual manner. The return of the slide valve of the distributor 2 to the neutral position is ensured by customary spring means not shown in the drawing.

Instead of using the distributor 2 shown in FIGURE 1, the momentary by-pass from the closed centre of the distributor may be realised by other suitable means.

For example, according to the variations shown in FIG- URE 2 and FIGURE 3, the usual type of distributor 4% with closed centre may be used instead of the distributor 2 in FIGURE 1.

FIGURE 2 shows the distributor 40 the slide valve of which is articulated at 38 to the lever '35. Between the two pipe systems 37 and 34- is disposed a by-pass device, consisting of a three-way valve 41 controlled by the linkage system 42 articulated at 43 to the lever 35. The valve .41 is shown in the medium position; movement in one direction or the other from this central position produces an instantaneous by-pass, communication between 34 and 37 being again cut oil? by continued movement of 41 in the same direction.

In FIGURE 3, the usual distributor 40 with closed centre has not been shown again. Only its connection at 38 on the lever 35' has been shown.

The three-way valve 41 in FIGURE 2 is replaced by a three-way distributor 44, the passage 45 communicating with the pipe system 37 and the two

passages

46, 47 communicating with the return pipes 34 leading to the cistern. The distributor slide valve 44 is hinged at 43 to the lever 35. It will be seen again that if the lever 35 moves the slide valve of the distributor to the right or left, it produces a momentary by-pass between the

pipe systems

34 and 37 which ceases when the slide valve continues to movein the same direction.

Any other equivalent device may be used to replace the

elements

41 and 44 if they produce the same effect, that is .to say a momentary by-pass as soon as the lever 35 which controls the distributor 40 is actuated.

What I claim is:

1. In a hydraulic pressure system comp-rising a delivery circuit, a pressuresource and a reservoir, said system including a by-pass valve connected between the pressure source and the reservoir and in communication therewith, said by-pass valve being responsive to pressure in the delivery circuit and to bias means, a return circuit, a reversible motor connected in series between said delivery circuit and said return circuit, a distributor valve in the path of flow of fluid from said reversible motor, a valve in said distributor valve having a neutral position in which the path of flow is obstructed and movable selectively to one of two operating positions in which the path of flow is unobstructed, one operating position of said valve in said distributor valve being on each side of said neutral position thereof, a supplementary by-pass means to bypass momentarily said distributor valve in response to displacement of the valve of said distributor valve to a position intermediate said neutral position and one of the operating positions whereby a momentary drop of pressure is caused in the delivery circuit which permits said bias means -.to actuate said first-named bypass valve and displace the same towards a closed position.

2. A system as set forth in claim 1, in which said distributor valve comprises a cylinder, a slide valve slidable in said cylinder and having portions thereof defining internal chambers, said cylinder and said chambers each having portions defining port means disposed to by-pass said motor in each of said intermediate positions of said valve.

3. A system as set forth in claim 1, in which said supplementary by-pass means includes a by-pass valve mounted in parallel relative to said distributor valve, said last-named by-pass valve comprising a movable valve element, and control means common to the valve of the said distributor valve and to said valve element.

4. A hydraulic pressure system comprising a pressure source, a delivery circuit, a return circuit, a reversible motor connected in series between said delivery circuit and said return circuit, a reservoir, 21 by-pass circuit connected between said delivery circuit and said reservoir and including a first bypass valve, throttle means in said by-pass circuit to develop a predetermined pressure intermediate the motor operating pressure and the pressure in the reservoir, said by-pass valve being responsive to the pressure in the delivery circuit to open the by-pass when the pressure in the delivery circuit raises above the motor operating pressure and to close the by-pass when the pressure in the delivery circuit drops below said intermediate pressure, a distributor valve in the path of flow of fluid for said motor, a valve in said distributor having a neutral position in which the path of flow is obstructed and movable selectively to one of two motor operating positions in which the path of flow is unobstructed, a supplementary by-pass means to by-pass said distributor and said motor, said supplementary by-pass means being operatively connected with said valve in said distributor, said supplementary by-pass means being disposed to open the bypass only when said valve in said distributor is in a predetermined position intermediate said neutral position and one of the operating positions, whereby a momentary drop of pressure is caused in the delivery circuit, as long as said valve in said distributor remains in said intermediate position, to actuate said first by-pass valve.

5. A hydraulic pressure system comprising a pressure source, a delivery circuit, a return circuit, a plurality of .parallelly connected motors between said delivery circuit and said return circuit, a reservoir, a by-pass circuit connected between said delivery circuit and said reservoir and including a first by-pass valve, throttle means in said by-pass circuit to develop a predetermined pressure intermediate the operating pressure of said motors and the pressure in the reservoir, said by-pass valve being responsive to the pressure in the delivery circuit to open the bypass when the pressure in the delivery circuit rises above the motors operating pressure and to close the by-pass when the pressure in the delivery circuit drops below said intermediate pressure, a distributor valve for each motor in the path of flow of fluid for the corresponding motor, a valve in said distributor having a neutral position in which the path of flow is obstructed and movable selectively to one of two operating positions of said motors in which the path of flow is unobstructed, a supplementary by-pass for each distributor, means to by-pass the corresponding distributor and the corresponding motor, said supplementary by-pass means being operatively connected with said valve in said distributor, said by-pass means being disposed to open the by-pass only when said valve in said distributor is in a predetermined position intermediate said neutral position and one of the operating positions, whereby a momentary drop of pressure is caused in the delivery circuit, as long as said valve in said distributor remains in said intermediate position, to actuate said first by-pass valve.

6. A hydraulic pressure system comprising a pressure source, a delivery circuit, a reversible motor connected in series between said delivery circuit and said return circuit, a reservoir, a by-pass circuit including a first by-pass valve and connected between said delivery circuit and said reservoir, said first by-pass valve including a cylinder and a differential pression having two positions, a by-pass position and a motor operating position and including a large face and a small face, said small face partly defining in said cylinder a chamber permanently connected to the delivery circuit, said large face partly defining in said cylinder a chamber connected With the delivery circuit when the piston is in the by-pass position, said piston being subjected to bias means acting on the opposite side relatively to said small face, throttle means in said by-pass circuit to develop a predetermined pressure intermediate the motor-operating pressure and the pressure in said reservoir, whereby said piston is displaced towards the by-pass position when the pressure in the delivery circuit rises above the motor operating pressure, maintained in said operating position by means of said intermediate pressure, and displaced towards the motor operating position in response to momentary drop of pressure in said delivery circuit, a distributor in the path of flow of fluid of said motor, a valve in said distributor having a neutral position in which the path of flow is obstructed and movable selectively to one of two motor operating positions, in which the path of flow is unobstructed, one operating position of said valve in said distributor valve being on each side of said neutral position thereof, a supplementary by-pass means to by-pass momentarily said distributor and said motor valve in response to displacement of the valve 6 of said distributor valve to a position intermediate said neutral position and one of the operating positions whereby a momentary drop of pressure is caused in said delivery circuit to displace said first by-pass valve towards its motor operating position.

References Cited in the file of this patent UNITED STATES PATENTS 2,057,087 De Millar Oct. 13, 1936 2,243,364 Trautman May 27, 1941 2,319,551 Linden et a1. May 18, 1943 2,649,688 Slomer Aug. 25, 1953

Claims

1. IN A HYDRAULIC PRESSURE SYSTEM COMPRISING A DELIVERY CIRCUIT, A PRESSURE SOURCE AND A RESERVOIR, SAID SYSTEM INCLUDING A BY-PASS VALVE CONNECTED BETWEEN THE PRESSURE SOURCE AND THE RESERVOIR AND IN COMMUNICATION THEREWITH, SAID BY-PASS VALVE BEING RESPONSIVE TO PRESSURE IN THE DELIVERY CIRCUIT AND TO BIAS MEANS, A RETURN CIRCUIT, A REVERSIBLE MOTOR CONNECTED IN SERIES BETWEEN SAID DELIVERY CIRCUIT AND SAID RETURN CIRCUIT, A DISTRIBUTOR VALVE IN THE PATH OF FLOW OF FLUID FROM SAID REVERSIBLE MOTOR, A VALVE IN SAID DISTRIBUTOR VALVE HAVING A NEUTRAL POSITION IN WHICH THE PATH OF FLOW IS OBSTRUCTED AND MOVABLE SELECTIVELY TO ONE OF TWO OPERATING POSITIONS IN WHICH THE LECTIVELY TO ONE OF TWO OPERATING POSITIONS IN WHICH THE PATH OF FLOW IS UNOBSTRUCTED, ONE OPERATING POSITION OF SAID VALVE IN SAID DISTRIBUTOR VALVE BEING ON EACH SIDE OF SAID NEUTRAL POSITION THEREOF, A SUPPLEMENTARY BY-PASS MEANS TO BY-PASS MONENTARILY SAID DISTRIBUTOR VALVE IN RESPONSE TO DISPLACEMENT OF THE VALVE OF SAID DISTRIBUTOR VALVE TO A POSITION INTERMEDIATE SAID NEUTRAL POSITION AND ONE OF THE OPERATING POSITIONS WHEREBY A MOMENTARY DROP OF PRESSURE IS CAUSED IN THE DELIVERY CIRCUIT WHICH PERMITS SAID BIAS MEANS TO ACTUATE SAID FIRST-NAMED BY-PASS VALVE AND DISPLACE THE SAME TOWARDS A CLOSED POSITION.