GB2198168A

GB2198168A - Hydraulic pulse generator

Info

Publication number: GB2198168A
Application number: GB08629062A
Authority: GB
Inventors: Stanislav Antonovich Lenenko; Oleg Anatolievich Myagkov; Vladimir Nikolaevich Vvedensky; Vladimir Ivanovich Tansky; Jury Alexeevich Manenkov; Jury Lvovich Asse; Fedor Alexeevich Tsyb
Original assignee: G SOJUZNY Z MEKH I KHIM OCHIST
Current assignee: G SOJUZNY Z MEKH I KHIM OCHIST
Priority date: 1986-12-04
Filing date: 1986-12-04
Publication date: 1988-06-08
Anticipated expiration: 2006-12-04
Also published as: GB2198168B; DE3642473C2; FR2608692B1; DE3642473A1; GB8629062D0; FR2608692A1

Abstract

A hydraulic pulse generator comprises a hydropneumatic accumulator (1 ) communicating with an inlet pipe (2) of an oscillations generator (3) having a housing (4) accommodating a main piston (5) to form therein an after-seat cavity (6) and a first after-piston cavity (7) communicable with a source (8) of continuous pressure, and a second hydropneumatic accumulator (9), a sub-membrane cavity (11) of which accommodates a first piston (12) with a piston rod (13) cooperating with the main piston (5) and defining a first rod end cavity (14) separated from the first after-piston cavity (7) by a partition (15) and communicating with the outside. The sub-membrane cavity (11) communicates through a by-pass (17) having a flow restrictor (18) with an outlet pipe (19). The housing (4) of the oscillations generator (3) is provided with a pulse formation chamber (21) accommodating a second piston (22) with a piston rod (23) capable of cooperation with the main piston (5) and defining in the pulse formation chamber (21) a second after-piston cavity (24) communicable with the outlet pipe (19) through a by-pass pipe (25), and a second rod end cavity (26) communicating with the outside. <IMAGE>

Description

HYDRAULIC PULSE GENERATOR This invention relates to hydraulic pulse-action machines, and more particularly to hydraulic pulse generators.

The invention can find application in the mining industry and in waterworks engineering for breaking rock by high-pressure pulsed water jets. It can also be used in power engineering for cleaning boler installations of heat -electric generation plants.

There is knows a hydraulic pulse generator comprising a hydropneumatic accumulator provided in a water delivery line and connected by a pipe to an oscillations generator having a housing accommodating a hollow piston, which defines chambers for closing and opening pressure relief, low and high pressure chambers, and a means for contJolling the movement of the hollow piston in the form of an air cap separated by a membrane into two cavities. One such cavity is filled with a compressed gas, whereas the other communicates the high pressure chamber through a variable flow restrictor with the chamber for opening pressure relief and through a valve with the outside.The low pressure chamber is connected to a pressure relief nozzle, whereas the high pressure chamber communicates with a working nozzle and with a pipe connecting the hydropneumatic accumulator with the oscillations generator.

Operation of this known hydraulic pulse generator involves accelerating the liquid in the pipe between the hydropneumatic accumulator and oscillations generator to be discharged through the relief nozzle of the oscillations generator and subsequently decelerating the liquid flow before the working nozzle of the machine.

This machine is disadvantageous because of the insf- ficient breaking power of the water jet pulse.

There is also known a hydraulic pulse generator comprising a hvdropneumatic accumulator communicating with an inlet pipe of an oscillations generator having a housing accommodating a main piston to define therein an after-seat chamber and an after-piston chamber communicating with a source of continuous pressure, and a second hydropneumatic accumulator having a membrane, a sub-membrane cavity of which accomaouates a piston with a piston rod cooperating with the main piston and forming a rod end cavity separated from the after-piston cavity by a partition and communicating with the outside, whereas the sub-membrane cavity ccmmunicates through a by-pass pipe having a flow restrictor with the outlet pipe and working nozzle Operation of this machine is based on storing energy in the second hydropneumatic accumulator to a certain level, which is followed by a discharge of high-pressure high -flow-rate pulse jet of liquid from the outlet working nozzle.

However, this prior art hydraulic pulse generator is inherently disadvantageous due to the low breaking oapacity of the water jet caused by delayed formation of the leading edge of the high pressure pulse resulting in a gradual application of load to the object to be broken, rather than in a sudden pulsed impact. This is accounted for by that certain structural relationship between the parameters of the seat and nozzle, as well as seat and main piston, may give rise to conditions under which an additional force acting on the main piston and resulting from the pressure exerted in the after-seat cavity on part of the sectional area of the main piston is not capable of sufficiently compensating for the forces of friction that arise.The main piston therefore departs slowly from the seat to delay the formation of the leading edge of the high pressure pulse before the outlet nozzle to result in a slow growth of pressure and, as a consequence, in reduced efficiency of hydraulic breaking. In addition, the main piston may assume an intermediate position to remain continuously in this position, whereby the flow of water through the seat and nozzle will be invariable and the hydropneumatic accumulator will not be charged. This in turn results in affected reliability and efficiency of the machine.

It is an object of this invention to increase the efficiency of hydraulic breaking by providing a steep leading edge of the, high pressure pulse.

Another object is to speed up the formation of the leading edge of the high pressure pulse to provide a higher power impact of the high pressure water jet on an obstacle to be broken.

One more object is to ensure a more reliable operation of the hydraulic pulse generator.

Yet another object is to provide a high pressure pulse of sufficient duration.

The objects of the invention are attained by that in a hydraulic pulse generator comprising a first hydropneumatic accumulator communicating with an inlet pipe of an oscillations generator having a housing accommodating a main piston to form therein an after-seat cavity and a first after-piston cavity communicating with a source of continuous pressure, and a second hydropneumatic accumulator having a membrane, a sub-membrane cavity of which accommodates a first rod end cavity separated from the first after-piston cavity by a partition and communicating with the outside, the sub -membrane cavity being communicated through a by-pass pipe having a flow restrictor with an outletXpipe of the oscillations generator, according to the invention the housing of the oscillations generator has a pulse formation chamber accommodating a second piston with a piston rod capable of cooperation with the main piston and defining in the pulse formation chamber a second after-piston cavity communicable with the outlet pipe of the oscillations generator through a second by-pass pipe, and a second rod end cavity communicating with the outside.

Preferably, the second rod end cavity of the pulse formation chamber communicates through a by-pass pipe having a valve with the sub-membrane cavity of the second hydropneumatic accumulator.

Advisably, the second rod end cavity of the pulse forma tion chamber communicates with the outside through another by-pass pipe having a valve.

In view of the aforedescribed, the provision in the proposed hydraulic pulse generator of the pulse formation chamber and the arrangement therein of the second piston with the piston rod cooperating with the main piston at the side of the inlet pipe, as well as the communication of the second after-piston cavity with the outlet pipe of the oscillations generator give rise to an additional force acting on the main piston at the side of the inlet pipe.

This ensures reliable and fast movement of the main piston away from the seat, whereby hydraulic losses are reduced and sharp increase in the pressure growth before the nozzle is ensured, thus providing steep leading edge of the high pressure pulse to break rock more efficiently. Also, thanks to the communication of the second rod end cavity with the sub-membrane cavity in the course of closing the seat by the main piston the growting pressure in the sub-membrane cavity is transmitted to the second rod end cavity to disengage the second piston with the piston rod at the side of the inlet pipe from the main piston. In consequence, the force hampering the travel of the main piston toward the seat is reduced1 thereby ensuring that the piston moves at a sufficient speed during closing and preventing stops of the main piston in intermediate positions, whereby the proposed hydraulic pulse generator operates more reliably and efficiently.

The invention will now be described in greater detail with reference to a specific embodiment thereof token in conjunction with the accompanying drawings the sole Figure of which represents a sectional view of the proposed hydraulic pulse generator according to the invention.

A hydraulic pulse generator comprises a hydropneumatic accumulator 1 connected at one side to a delivery line or to a pump (not shown), and at the other side to an inlet pipe 2 of an oscillations generator 3. The oscillations generator 3 has a housing 4 accommodating a main piston 5 forming an after-seat cavity 6, and an after-piston cavity 7 communicating with a source 8 of continuous pressure. The hydraulic pulse generator also comprises a second hydropneumatic accumulator 9 having a membrane 1;O, a sub-membrane cavity 11 of which accommodates a first piston 12 with a piston rod 13 cooperating with the main piston 5 and defining inside the housing 4 a first rod end cavity 14 separated from the first after-piston cavity 7 by a partition 15 and communicating with the outside through a hole 16.The sub-membrane cavity 11 communicates by way of a by-pass pipe 17 having a flow restrictor 18 with an outlet pipe 19 and with a nozzle 20 attached thereto. In addition, provided at the side of the inlet pipe 2 and hydropneumatic accumulator 1 in the housing 4 of the oscillations generator 3 is a pulse formation chamber 21 in which there is disposed a second piston 22 with a piston rod 23 cooperating with the main piston 5. The second piston 22 divides the pulse formation chamber 21 into a second after-piston cavity 24 communicating with the outlet pipe 19 through a by-pass pipe 25, and a second rod end cavity 26 connected through a by-pass pipe 27 having a flow restrictor 28 to the sub -membrane cavity 11 of the second hydropneumatic accumulator 9, and through another by-pass pipe 29 having a valve 30, with the outside.The h0dropneumatic accumulator 1 comprises a membrane 31, which is forced under the action of compressed air to bear on a grid 32. The membrane 10 of the second hydropneumatic accumulator 9 is likewise forced by the action of compressed air to bear on a grid 33, whereas the source 8 of continuous pressure is provided with a valve 34.

The after-seat cavity 6 of the oscillations generator 3 has a seat 35.

The hydraulic pulse generator operates in the following manner.

The valve 34 is opened to communicate the first afterpiston cavity 7 with the source 8 of continuous pressure, such as an oil station. Therewith, the valve 28 is open, whereas the valve 30 in the by-pass pipe 29 is closed.

The sub-membrane cavity 11 therefore communicates along the by-pass pipe 27 with the second rod end cavity 26. The main piston 5 is caused by the action of continuous pressure at the side of the first after-piston cavity 7 from the source 8 of continuous pressure to be forced to the seat 35 to thereby cut off the flow of water from the inlet pipe 2 to the after-seat cavity 6 and further to the outlet pipe 19 and nozzle 20. In consequence, the water delivered from the pump or from the feeding line, while occupying the interiors of the hydropneumatic accumulator 1 and inlet pipe 2, acts on the membrane 31 to force it from the grid 32 and compress the gas over the membrane 31, whereby the hydropneumatic accumulator 1 is charged.Under the action of pressure exerted on the ends of the rods 13 and 23 of the respective pistons 12 and 22 in the inlet pipe 2 3nd first after-piston cavity 7 there pistons are caused to move accordingly toward the second after-piston cavity 24 and sub-membrane cavity 11 and be brought out of engagement with the main piston 5. Therewith, the first after-piston cavity 7 is subjected to a continuous pressure, the interior of the inlet pipe 2 is under an increasing charging pressure, whereas tle second after-piston cavity 24, second rod end cavity 20, and sub-membrane cavity II are under the atmospheric pressure. The membrane 10 of the second hydropneumatic accumulator 9 is forced to the grid 33.

Charging of the h & ropneumatic accumulator 1 continues until the pressure in the inlet pipe 2 grows to a magnitude, there the force it exerts on the surface area of the main piston 5 at the side of the seat 35 prevails over the force of continuous pressure in the first after-piston cavity 7 exerted on the entire surface area of the main piston 5.

As soon as this occurs, that is a resulting force directed toward the first after-piston cavity 7 is generated, the main piston 5 begins to depart from the seat 35 to intercommunicate the inlet pipe 2 and the after-seat cavity 6 through a clearance between the seat 35 and the main piston 5. The resultant force tends to grow from the pressure of water exerted on the released surface area of the main piston 5 in the after-seat cavity 6. In addition, from the after-seat cavity 6 water flows to the outlet pipe 19 and nozzle 2u to escape therefrom toward an object to be broken. At the same time, from the outlet pipe 19 water flows along the by-pass pipes 17 and 25 to the sub-membrane cavity 11 and second after-piston cavity 24.The pressure of water in this second after-piston cavity 24 grows momentarily to the charging pressure. In the sub-membrane cavity II the pressure growth will occur with a certain amount of delay caused by the provision of the flow restrictor 18 in the by-pass pipe 17 and the presence of gas in the second hydropneumatic accumulator 9. In consequence, a force will arise at the side of the second after-piston cavity 24 causing the second piston 22 to move toward the second rod end cavity 26. The second piston 22 with the rod 23 are therefore brought into engagement with the main piston 5 to enhance the resultant force acting on the piston 5 and speed-up the travel of the piston 5. Accordingly, the higher is the speed of travel of the main piston 5, the faster is the rate of pressure growth in the outlet pipe 19 before the nozzle 20, and the steeper is the leading edge of the high pressure pulse.

Discharge phase in the operation of the hydropneumatic accumulator 1 begins with the depature of the main piston 5 from the seat 35. Water escapes from the nozzle 20 toward the object to be broken, and flows along the by-pass pipe 17 under the same pressure to the sub-membrane cavity 11, and along the by-pass pipe 27 to occupy the second rod end cavity 26. However, by virtue of the provision of the flow restrictor 18 and second hydropneumatic accumulator 9, the pressure of water in the sub-membrane cavity 11 and in the second rod end cavity 26 to grows slowly, and thanks to the substantial surface area of the first piston 12 will never be higher than the pressure in the after-seat cavity 6 prior to termination of the discharge process.In view of the aforedescribed, during the discharge of the hydropneumatic accumulator 1 the pressure of water in the inlet pipe 2, after-seat cavity 6 and second after-piston cavity 24 tends to reduce, whereas the pressure in the sub-membrane cavity II and second rod end cavity 26 at the start of the discharge of the hydropneumatic accumulator 1 rises due to the movement of the membrane 10 away from the grid 33 and occupation of the space therebetween by water, and reaches the discharge pressure at the point, when the pressure of gas and water exerted on the membrane 10 at both sides thereof equals.Under the action of the discharge pressure in the second rod end cavity 26, the second piston 22 with the rod 23 start to move toward the second after-piston cavity 24, thereby forcing water therefrom along the by-pass pipe 25 to the outlet pipe 19. Accordingly the rod 23 of the second piston 22 is brought out of eRgasement with the main piston 5. The pressure in the sub-membrane cavity 11 and in the second rod end cavity 26 is gradually reduced, and is maintained at a sufficient level thanks to the movement of the membrane 10 toward the grid 33 and the flow of water from the space therebetween under the action of compressed gas in the cavity.When the force acting on the main piston 5 at the side of the after-seat cavity 6 becomes less in mag nitude than the force acting on the main piston 5 at the side of the first after-piston cavity 7 and sub-membrane cavity 11, the main piston 5 moves toward the seat 35. As the travel of the main piston 5 continues, the pressure in the after-seat cavity 6, in the space before the nozzle 20, and in the second after-piston cavity 24 tends to reduce, whereas the pressure in the sub-membrane cavity II and in the second rod end cavity 26 becomes lower than the initial discharge pressure. The main piston 5 arrives to the seat 35 to block this seat. The pressure in the after -seat cavity 6, and in the outlet pipe 19 before the nozzle 2O is brought down to the atmospheric.This pressure redestribution results in that during the movement of the main piston 5 the action thereon of the first piston 12 with the rod 13 is enhanced, whereas the counteraction of the second piston 22 with rod 23 is dimigsished, which ensures a sudden drop in pressure before the nozzle 20, and a sufficiently steep trailing edge of the pressure pulse, i.e., accurate and reliable operation of the hydraulic pulse generator. The start of travel of the main piston 5 toward the seat 35 terminates the discharge cycle of the hydropneumatic accumulator 1, and after the main piston 5 seats in the seat 35 charging is recommenced and the ope- ration cycle is repeated.

Subsequent to the seating of the main piston 5 in the seat 35, the pressure in the after-seat cavity 6 and in the second after-piston cavity 24 momentarily aoaches the atmospheric, and the second piston 22 with the rod 23 is not in engagement with the main piston 5. When the membrane 10 contacts the grid 33, the pressure in the sub-membrane cavity 11 and in the second rou end cavity 26 equals the atmospheric . After this the rod 13 of the first piston 12 is caused under the action of continuous pressure from the first after-piston cavity 7 to move again toward the second hydropneumatic accumulator 9 and be brought out of engagement vlith the main piston 5. The hydraulic pulse generator is therefore again prepared for the charging phase.

In the case, when the valve 28 in the by-pass pipe 27 is closed, while the valve 30 in the by-pass pipe 29 is opened, the second rod end cavity 26 is discommunicated from the sub-membrane cavity 11 to communicate with the atmosphere. Operation of the hydraulic pulse generator in the phase of charging the hydropneumatic accumulator 1 is here identical to the aforedescribed, whereas in the phase of discharge it differs by that the second piston 22 with the rod 23 continuously cooperates with the main piston 5. This results in an additional force preventing the movement of the main piston 5 toward the seat 35, and consequently in forces acting on the main piston 5 at the side of the first after-piston cavity 7 and sub-membrane cavity 11 through the first piston 12 with the rod 13.

As a consequence, the movement of the main piston 5 slows down accompanied by an increase in the discharge duration, that is the duration of the high pressure pulse through changing the steepness of the trailing edge of the pulse, whereby it becomes flattened. This change in the trailing edge of the pulse is dictated by the conditions of hydraulic breaking. Breaking hard rock necessitates steep leading and trailing edges of the pulse. With this aim in view, the sub-membrane cavity II is connected to the second rod end cavity 26 through the by-pass pipe 27. The valve 28 is then opened, and valve 30 is closed. For breaking soft rock with tbe utmost efficiency it is possible to use a steep leading edge of the pulse with sloping trailing edge and increased duration of the high pressure pulse.

Accordingly, the sub-membrane cavity 11 is disconnected from the second rod end cavity 26 by closing the valve 28, the second rod end cavity 26 being communicated with the outside by opening the valve 30.

The machine embodying the present invention allows a more efficient hydraulic breaking of rock thanks to the strep leading and variable trailing pulse edges, increased impact power of water jet, extended high pressure pulse duration, and improved overall reliability.

Claims

1. A hydraulic pulse generator co-prising a first hydropneumatic accumulator communicating with an inlet pipe of an oscillations generator having a housing accommodating a Lain piston to forw therein a after-seat cavity and a first after-piston cavity communicating with a source of continuous pressure, and a second hydropneuma- tic accumulator connected to the housing of the oscillations generator and having a membrane, a sub-membrane cavity of which accmmodates a first piston with a piston rod forming a first rod ena cavity conniunicating with the outside and separated fro the first after piston cavity by a partitio., the sub-memrane cavity being commmunicated through a first by-pass pipe having a flow restrictor with an outlet pipe of the oscillations generator, the housing of the oscillations generator having a pulse formation chamber accomodating a second piston with a piston rod capable of cooperation with the Liain piston and defining in the pulse formation chablbe: a second after-piston cavity couunicable with the outlet pipe of the oscillations generator through a second by-pass pipe, and a second rod end cavity communicating with the outside

2. A hydraulic pulse generator as claimed in claim 1, in which the second rod ena cavity of the pulse formation chamber communicates through a third by-pass pipe having a first valve with the sub-membrane cavity of the second hydropneumatic accuLulator.

3. A hydraulic pulse generator as claimed in claim 1 or 2, in which the second rod end cavity of the pulse formation chamber communicates with the outside through a fourth by-pass pipe having a second valve.

4. A hydraulic pulse generator substantially as described in the description with reference to the accompanying drawings.