GB1587332A - Hydraulic drives - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO HYDRAULIC DRIVES (71) We, ANATOLY SERGEEVICH GRI GORENKO, ulitsa Tovstukho, 1, kv. 21, Omsk, JURY ANTONOVICH MOROZ, ulitsa Fugenfirova, 11, kv. 91, Omsk, GERMAN NIKOLAEV ICH KUZNETSOV, ulitsa Romanenko, 8, kv.

46, Omsk, VLADIMIR IVANOVICH VIMBA, ulitsa 50 let VLKSM, 4v, kv. 55, Omsk, VLADIMIR VLADISLAVOVICH LANDYSHEV, ulitsa 50 let VLKSM, 14a, kv. 22, Omsk, JURY ALEXANDROVICH BOCHAROV, 15 Parkovaya, 18, korpus 1, kv. 109, Moscow, and ANATOLY VASILIEVICH SAFONOV, Sevastopolsky prospekt, 51, korpus 1, kv. 11 Moscow, all of the U.S.S.R., all citizens of the Union of Soviet Socialist Republics, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a hydraulic drive and can be utilized in presses and power hammers; the invention is particularly useful in hydraulic screw presses.

According to the invention there is provided a hydraulic drive comprising a gashydraulic accumulator for providing hydraulic fluid under a preset pressure, a pump for delivering hydraulic fluid from a reservoir of said hydraulic fluid, a chamber for containing hydraulic fluid and divided by a piston into two spaces, the volume of said chamber being at least equal to a volume of hydraulic fluid required by a device operated by the hydraulic drive, a first pipeline connecting said accumulator with one of the spaces of said chamber, a second pipeline leading from the other space of said chamber and for connection to said device, said second pipeline being provided with a closing device for cutting off the supply of hydraulic fluid to said device, a distributing device for controlling the opening and closing of said closing device, a third pipeline connecting said pump with said other space of the chamber for the replenishment of hydraulic fluid in said other space of the chamber, a non-return valve installed in said third pipeline, a fourth pipeline connecting said first pipeline to the pump for the delivery of hydraulic fluid from the reservoir to the accumulator.

An advantage of the hydraulic drive of the invention is that, owing to said connection of the accumulator and chamber which has an accurately defined piston stroke, the accumulator receives one and the same amount of fluid of each working cycle of a given device.

This guarantees a constant fluid level in the charged accumulator, and a constant initial pressure.

In addition, the provision of the piston in the chamber prevents the gas from penetrating into the device's hydraulic system.

To facilitate operation, the pump is connected to the first pipeline through a distributing device which allows the delivery of hydraulic fluid to the accumulator by the pump and also allows discharge of hydraulic fluid from the accumulator.

An advantage of such a connection is that it permits changes in the volume of fluid in the accumulator; this results in changes in the volume of gas and, as a consequence, permits control of pressure in the accumulator.

Now the invention will be described in detail by way of example with reference to the accompanying drawing which gives a schematic outline of one embodiment of hydraulic drive according to the present invention.

The hydraulic drive comprises a gashydraulic accumulator 1, a pump 2, a chamber 3 with a movable piston 4, and first, second, third and fourth pipelines 5, 6, 8 and 7 respectively which connect the abovementioned elements in a manner described in detail hereinbelow.

The hydraulic drive also comprises a storage reservoir 9 holding hydraulic fluid delivered by the pump 2.

The gas-hydraulic accumulator 1 can be any known type of accumulator whose internal space holds a required volume of gas and a required volume of hydraulic fluid.

The chamber 3 has a cylindrical casing 10 having sufficient strength to accommodate the working pressure of the fluid. This casing has holes 11 and 12 for admitting the hydraulic fluid into, and discharging it from, the chamber. The chamber 3 is divided internally by a piston 4 into two spaces, one above the piston 4, as shown in the drawings, and one below the piston 4, whose volume is determined by the position of the piston so that the chamber 3 is, virtually, a piston accumulator with two fluid-filled spaces. The full volume of the chamber 3 and of the fluid it contains, taking no account of the piston size, should be equal to at least the volume of the working cylinder of the press (not shown in the drawing) utilizing the hydraulic drive.

Connected to the hole 11 is the first pipeline 5 which connects the chamber 3 to the accumulator I while the hole 12 is connected to the second pipeline 6 connecting the chamber 3 with the press via a closing device 13. The closing device 13 consists of a body 14 with holes 15 and 16, and a valve 17 urged downwardly by a compression spring 18. The closing device 13 is controlled by an electromagnetic two-way slide-valve distributor 19 which is connected to said device 13 by two pipelines 20 and 21 and which is also connected to the reservoir 9.

Connected to the hole 15 is a first portion of the second pipeline leading to the hydraulic cylinder 23 of the press (not shown in the drawing).

The third pipeline 8 is connected to the second pipeline 6 and incorporates a nonreturn valve 24.

In the fourth pipeline 7, which connects the pump 2 with the first pipeline 5, is mounted a three-way electromagnetic slidevalve distributor 25.

The hydraulic drive functions as follows: In an initial position all the elements of the drive occupy the positions shown in the drawing.

The electromagnet of the distributor 19 is energized and the distributor is shifted from the position shown in the drawing to a position in which the above piston space of the chamber 3 is in communication with the reservoir 9 through the pipeline 21.

The valve 17 is thus lifted by the fluid pressure from its seat and opens communication of the fluid between the holes 15 and 16.

Tus the hydraulic fluid from the upper, above-piston space of the chamber 3 passes through the closing device 13 and the second pipeline into the press cylinder 23.

The hydraulic fluid is forced out of the above-piston space of chamber 3 by the piston 4 whose lower end is acted upon by the force of the fluid entering the hole 11 from the accumulator 1 through the first pipeline 5.

Thus, the fluid enters the press cylinder 23 only from the upper space of the chamber 3 and this space is isolated by the piston 4 both from the lower space of the chamber and from the accumulator 1. This ensures safety in emergency situations, for example when the hydraulic system of the press becomes leaky. In this case the accumulator will not be completely discharged because the travel of the piston 4 is limited by the upper part of the chamber 3.

In addition, gas is prevented from penetrating the hydraulic system of the press from the accumulator 1.

During normal operation of the hydraulic drive with the hydraulic cylinder 23 of the press, hydraulic fluid from the upper space of the chamber 3 is lost and the pressure in the accumulator 1 drops from the initial value to a lower level.

On completion of the working stroke of the press cylinder 23 the electromagnet of the distributor 19 is de-energized and the distributor is shifted to an initial position in which the above-piston space is put in communication through the pipelines 21 and 20 with the under-piston space so that spring 18 forces the valve 17 down on its seat. The hydraulic cylinder 23 is then cut off from the hydraulic drive.

Then the pump 2 starts operation and delivers hydraulic fluid from the reservoir 9 through the third pipeline 8, the non-return valve 24 and the pipeline 6 into the upper space of the chamber 3.

The force of the fluid applied to the upper end of the piston 4 lowers said piston thus forcing the fluid out of the lower space of the chamber 3 through the hole 11 and pipeline 5 into the accumulator 1 wherein pressure rises to the initial value. The pressure built up by the pump is higher than the initial pressure in the accumulator 1.

In its lowermost position, the end of the piston 4 comes to bear against the bottom of the chamber 3 so that the further pressure rise in the accumulator is impossible.

Thus, pressure in the accumulator is prevented from rising higher than the preset initial pressure.

If the initial pressure in the accumulator has to be raised, it is necessary to energize the right-hand (in the drawing) electromagnet 25a of the distributor 25. In this case the distributor 25 will occupy a position in which the pump 2 delivers an additional amount of fluid into the accumulator 1 from the reservoir 9 through the pipelines 7 and 5.

If the initial pressure in the accumulator 1 has to be decreased, it is necessary to energize the left-hand electromagnet 25b (in the drawing) of the distributor 25. Then the distributor comes to a position in which the accumulator 1 is connected through the pipelines 5 and 7 with the reservoir 9. The fluid is forced by the pressure of gas out of the accumulator 1 into the reservoir 9. Since the volume of fluid in the accumulator decreases and the volume of gas increases, the initial pressure drops. As the preset pressure is reached, the electromagnet of the distributor 25 is de-energized and the distributor comes to the initial position.

It should be borne in mind that the abovedescribed device with electromagneticallycontrolled elements must have an electronic control unit which, however, is not illustrated in the drawings since it is well known to those skilled in the art. Any unit ensuring the above-mentioned operations of energizing and de-energizing the electromagnets can be utilized in the claimed hydraulic drive.

WHAT WE CLAIM IS: 1. A hydraulic drive comprising a gashydraulic accumulator for providing hydraulic fluid under a preset pressure, a pump for delivering hydraulic fluid from a reservoir of said hydraulic fluid, a chamber for containing hydraulic fluid and divided by a piston into two spaces, the volume of said chamber being at least equal to a volume of hydraulic fluid required by a device operated by the hydraulic drive, a first pipeline connecting said accumulator with one of the spaces of said chamber, a second pipeline leading from the other space of said chamber and for connection to said device, said second pipeline being provided with a closing device for cutting off the supply of hydraulic fluid to said device, a distributing device for controlling the opening and closing of said closing device, a third pipeline connecting said pump with said other space of the chamber for the replenishment of hydraulic fluid in said other space of the chamber, a non-return valve installed in said third pipeline, a fourth pipeline connecting said first pipeline to the pump for the delivery of hydraulic fluid from the reservoir to the accumulator.

2. A hydraulic drive according to Claim I wherein the pump is connected to the first pipeline through a distributing device in the form of a three-way slide valve which allows the delivery of hydraulic fluid to the accumulator by the pump and also allows discharge of hydraulic fluid from the accumulator.

3. A hydraulic drive according to Claim 2 wherein the distributing device is an electromagnetic three-way slide valve.

4. A hydraulic drive substantially as disclosed in the description with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. distributor 25 is de-energized and the distributor comes to the initial position. It should be borne in mind that the abovedescribed device with electromagneticallycontrolled elements must have an electronic control unit which, however, is not illustrated in the drawings since it is well known to those skilled in the art. Any unit ensuring the above-mentioned operations of energizing and de-energizing the electromagnets can be utilized in the claimed hydraulic drive. WHAT WE CLAIM IS:

1. A hydraulic drive comprising a gashydraulic accumulator for providing hydraulic fluid under a preset pressure, a pump for delivering hydraulic fluid from a reservoir of said hydraulic fluid, a chamber for containing hydraulic fluid and divided by a piston into two spaces, the volume of said chamber being at least equal to a volume of hydraulic fluid required by a device operated by the hydraulic drive, a first pipeline connecting said accumulator with one of the spaces of said chamber, a second pipeline leading from the other space of said chamber and for connection to said device, said second pipeline being provided with a closing device for cutting off the supply of hydraulic fluid to said device, a distributing device for controlling the opening and closing of said closing device, a third pipeline connecting said pump with said other space of the chamber for the replenishment of hydraulic fluid in said other space of the chamber, a non-return valve installed in said third pipeline, a fourth pipeline connecting said first pipeline to the pump for the delivery of hydraulic fluid from the reservoir to the accumulator.

2. A hydraulic drive according to Claim I wherein the pump is connected to the first pipeline through a distributing device in the form of a three-way slide valve which allows the delivery of hydraulic fluid to the accumulator by the pump and also allows discharge of hydraulic fluid from the accumulator.

3. A hydraulic drive according to Claim 2 wherein the distributing device is an electromagnetic three-way slide valve.

4. A hydraulic drive substantially as disclosed in the description with reference to the accompanying drawing.