US3851667A

US3851667A - Pulsator for hydraulic systems controlling actuating mechanisms

Info

Publication number: US3851667A
Authority: US
Inventors: V Platonov; V Popov; I Kononov; I Maslennikov; V Goryainov
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-02-13
Filing date: 1973-02-13
Publication date: 1974-12-03
Anticipated expiration: 1991-12-03

Abstract

In the housing of a pulsator are accommodated a delivery valve and on its opposite ends, a rigidly connected pusher serving for opening the valve and an air cylinder for actuating said valve at its closing coaxially mounted relative thereto. A cavity between the pusher and the delivery valve is constantly connected to a high-pressure main and to an actuating mechanism, a cavity above the valve being connected to a drain main, with a cavity below the pusher being connected to the high-pressure main via a non-return valve, and to a liquid drain main via a valve unit provided with a throttle. The valve unit allows the cavity below the pusher to be completely shut off when the valve is raised and to place it in communication with the liquid drain main when the valve is lowered, which, in turn, increases the high-speed response of the valve, and hence, the number of pulsations per unit of time.

Description

United States atent 1 1 Goryainov et al.

[ Dec. 3, 1974 PULSATOR FOR HYDRAULIC SYSTEMS CONTROLLING ACTUATING MECHANISMS [76] Inventors: Vladimir lvanovich Goryainov, 50,

kv. 2 p/o Chelobatievo, Mytischnsky raion, Moskovskaya Oblast; Ivan Vasilievich Kononov, 40, kv. 4 ulitsa Torpedo, Vorenezh; Ivan Egorovich Maslennikov, 26, kv. 82 ulitsa Druzhinnikov, Vorenezh; Vladimir Nikiforovich Platonov, ulitsa 9 Yanvarya 49, kv. 45, Vorenezh; Vyacheslav Evgenievich Popov, ulitsa Peshe Streletskaya 125, kv. 76, Vorenezh, all of USSR.

[22] Filed: Feb. 13, 1973 [21] Appl. No.: 332,152

[52] US. Cl. 137/624.14, 91/50 [51] Int. Cl F011 9/02 [58] Field of Search 91/50; 137/624.13, 624.14,

[56] References Cited UNITED STATES PATENTS 2,378,979 6/1945 Burt 91/50 X 3,141,384 7/1964 Hoffman 91/50 X 3,345,915 10/1967 Dotto 137/624.l4 x FOREIGN PATENTS OR APPLICATIONS 1,309,903 10/1962 France l37/624.l4 1,225,496- 9/1966 Germany 91/50 Primary Examiner-William R. Cline Assistant ExaminerGerald A. Michalsky Attorney, Agent, or FirmHolman & Stern [5 7] ABSTRACT In the housing of a pulsator are accommodated a delivery valve and on its opposite ends, a rigidly connected pusher serving for opening the valve and an air cylinder for actuating said valve at its closing coaxially mounted relative thereto.

A cavity between the pusher and the delivery valve is constantly connected to a high-pressure main and to an actuating mechanism, a cavity above the valve being connected to a drain main, with a cavity below the pusher being connected to the high-pressure main via a non-return valve, and to a liquid drain main via a valve unit provided with a throttle. The valve unit allows the cavity below the'pusher to be completely shut off when the valve is raised and to place it in communication with the liquid drain main when the valve is lowered, which, in turn, increases the high-speed response of the valve, and hence, the number of pulsations per unit of time.

3 Claims, 1 Drawing Figure BACKGROUND OF THE INVENTION The present invention relates to devices producing pulsating loads in hydraulic systems controlling actuating mechanisms. 7

It is advantageous to utilize the pulsator, realized according to the present invention, in the forge-press machine-building industry, and in particular, in presses PRIOR ART Known in the art are pulsators for hydraulic systems controlling actuating mechanisms of hydraulic presses. The housings of such pulsators accomodate a delivery valve and mounted coaxially with said valve, on its opposite ends, an air cylinder and a pusher adapted to actuate the delivery valve in closing and opening, respectively.

Said elements form cavities, in combination with I each other and the housing, constantly communicating with the hydraulic system mains. The cavity defined between the delivery valve and the pusher permanently communicates with a high-pressure main and with actuating mechanisms; the cavity above the delivery valve communicates with a liquid drain main; the cavity below the pusher communicates with the high-pressure main via a non-return valve, and with the liquid drain main, via a pipeline equipped with a throttle.

The delivery valve of pulsators is in a contacting arrangement with the pusher due to its being loaded by a spring, with the latter operating in the oscillating duty with a frequency of several cycles per second and an oscillation amplitude equal to the valve opening stroke.

In said pulsators the closing time of the delivery valve, and also, that of the pusher and movable component of the air cylinder depends on the flow crosssection of the throttle mounted on a pipeline connecting the cavity below the pusher to the drain main. The larger the throttle flow cross-section, the less time is required for closing the delivery valve, which contributes to increasing the'oscillation frequency and hence, the pulsator efficiency. However, the flow cross-section of said throttle should be such as to ensure, at the instant the delivery valve opens, a pressure drop between the cavity below the pusher and the cavity between the latter and the delivery valve, sufficient for displacing the movable elements.

In other words, in order to effect quick closing of the delivery valve, the throttle flow cross-section should be these pulsators in hydraulic systems whose actuating mechanisms develop forces exceeding 200 to 300 t,

(ton force), with the liquid consumption exceeding 300 l/min, it is impossible to obtain an oscillation frequency higher than 10 to 15 c.p.s.

The constantly communicating cavity below the pusher with the drain main affects adversely the pulsator operation, since with the delivery valve opening a portion of compressed liquid is lost (up to percent), which affects the pulsator efficiency.

A further drawback of the known pulsators is also in thatv the contact between the delivery valve and the pusher is ensured by means of a spring disposed in the cavity below the pusher. In order to ensure normal operation of the pulsator with said means effecting contact between the valve and the pusher, it is necessary that the pressure rise of liquid per cycle be effected at the same speed both in the cavity below the pusher and the cavity between the pusher and delivery valve, i.e., the resistances of pipelines connecting said cavities should be equal.

Such a condition cannot be achieved in practice, since the pipeline connecting the cavity below the pusher to the high-pressure main mounts a non-return valve adjusted to a pressure drop exceeding 10 kgf/cm, at which the spring force is insufficient to ensure reliable contact between the valve and the pusher at the instant the cavities are filled with liquid, resulting in the pusher parting from the valve, thereby disturbing the operating duty.

To ensure constant contact between the valve and the pusher, a spring, whose force exceeds that exerted by the pressure drop should be provided.

In practice the spring force exceeds 1,000 kgf, taking into account the additional resistance in the pipeline. With the system operating in an oscillating duty at a frequency of several cycles per second, this tends to decrease sharply the durability of the spring, and hence,

large, while in order to ensure the required pressure drop, said cross-section should be as small as possible, or equal to zero.

Practically, the closing time of the delivery valve constitutes hundredths of a second, and hence when using the reliability of the pulsator.

Independent connection of the delivery valve and the pusher involves a considerable increase in the pulsator sizes, on the one band, due to a large flow cross-section of the delivery valve and diameter of the pipeline connecting the cavity below the pusher to the highpressure main, and, on the other hand, due to the fact that the air cylinder force should exceed the spring force below the pusher.

In addition, well known in the art are slide-valve type pulsators for hydraulic systems controlling actuating mechanisms. 1 v

The principal component in these pulsators is a movable element (a slide valve or a disk) disposed in the pulsator housing and adapted to be displaced by an individual drive according to a preset law actuated. Ports (holes) provided in the slide valve and the housing are matched in the course of operation and communicate the actuating mechanisms alternately with the highpressure main and with the drain main.

Pulsators of the slide-valve type have the following drawbacks:

the slide valve ports fail to be opened in synchronism with the supply of liquid delivered by the high-pressure main;

constant leaks of the working fluid as a result of failure to ensure complete leak-tightness of the slide valve;

usage of mineral oil as the working fluid possessing a relatively low modulus of elasticity, which reduces the hydraulic system efficiency at pulsating loads due to excessive energy losses for compressing the fluid; and

more stringent requirements placed upon oil cleanliness, since even minor contamination leads to rapid wear of the rubbing surfaces, increases leaks and shorter service life of the pulsator.

Widely known are also plunger-type pulsators for hydraulic systems controlling actuating mechanisms, wherein a plunger serves as the movable element producing pulsations of the liquid pressure.

Such a plunger receives the reciprocating motion from an eccentric mechanism or a cam mechanism set in rotation by individual motors.

A principal drawback of the plunger-type pulsator is failure to provide a reliable, high-speed and relatively powerful drive (eccentric-plunger link), required for feeding the required volume of fluid (100 to 500 cm per pulse at a speed of 1,000 to 1,500 rpm). Moreover, said pulsators fail to ensure the required parameters of the hydraulic system, since, for example, the fluid pressure, oscillation amplitude, etc., are dependent on the volume of the fluid delivered by the plunger during one stroke.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the present invention to ensure a highspeed response of the delivery valve during its opening and closing and to obtain, respectively, high pulsation frequency.

Another object of the present invention is to provide a required flow rate of the delivery valve, making it possible to construct hydraulic systems having largercapacity actuating mechanisms with a higher frequency of pulsating loads.

Still another object of the present invention is to ensure leak-tightness of pulsator cavities subjected to high pressures.

A further object of the invention is to obtain simplicity and convenience in manipulating the pulsator.

It is advantageous that the valve unit be provided with a housing accommodating a spring-loaded movable element defined by a cylinder, whose side surface provides, in combination with the housing, an annular chamber communicating with the cavity below the pusher, while whose end surface provides, in combination with the housing, a chamber communicating with the drain main, with the end surfaces of the movable element comprising an end piece adapted to interact with the'movable element of the air cylinder.

Such a design of the valve unit makes it possible to reliably seal the cavity below the pusher as the delivery valve is opened and to comparatively quickly drain the liquid from the cavity below the pusher as the delivery valve is closed. Besides, such a construction is reliable in service and ensures a long service life.

It is also advantageous to mount in the cavity above the delivery valve, a piston having a cross-sectional area somewhat exceeding that of the delivery valve and to adapt the end surfaces of said piston for interaction with the delivery valve and movable element of the air cylinder, respectively.

The installation of the piston in the cavity above the delivery valve makes it possible to utilize the energy of the liquid stream discharged to drain, which is conducive to complete opening of the delivery valve.

A pulsator for hydraulic systems controlling actuating mechanisms embodying the present invention al- Yet another object of the invention is to ensure reliability and longevity of the pulsator.

In accordance with the invention, a pulsator for hydraulic systems controlling actuating mechanisms is provided in whose housing are disposed a delivery valve and mounted coaxially with said valve, on its opposite ends, a controlled air cylinder and a pusher, adapted to actuate the delivery valve in closing and opening, respectively, the cavity between the delivery valve and the pusher constantly communicating with a high-pressure main and with an actuating mechanism, the cavity above the delivery valve communicating with the liquid drain main, the cavity below the pusher communicating with the high-pressure main via a nonreturn valve, and with the liquid drain main via a pipeline with a throttle, wherein, according to the invention, a pipeline connecting the cavity below the pusher to the liquid drain main mounts, ahead of the throttle, a valve unit, whose movable element is adapted to shut ofi' said pipeline as the delivery valve is opened, and to be actuated by a movable element of the air cylinder at the end of the delivery valve stroke during its opening, in order to connect the pipeline to the liquid drain main as the delivery valve is closed, with the delivery valve and the pusher being rigidly interconnected.

lows for the required quick response of the delivery valve to be obtained at its actuation.

Moreover, a higher flow rate when draining the liquid from the system is ensured, since such a design of the pulsator makes it possible to increase the delivery valve and pusher sizes, reducing, at the same time, the volumes of respective cavities.

The advantages of the pulsator hereinabove described permit its utilization in hydraulic systems comprising actuating elements which develop a force of from to 2,000 t (ton force) with high frequencies of pulsating loads (up to 30 50 c.p.s.).

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be explained in greater detail withreference to an embodiment thereof which is represented in the accompanying drawing, in which the sole FIGURE is a schematic representation of a pulsator for hydraulic systems controlling an actuating element.

DETAILED DESCRIPTION OF THE INVENTION The pulsator has a housing 1 accommodating a delivery valve 2 and a pusher 3, mounted in coaxial relationship.

The housing 1, valve 2 and pusher 3 define a cavity 4 and a cavity 5 below the end face of the pusher 3.

To overcome any forces caused by the pressure drop in the cavities 4 and 5, for actuating the pusher 3, and for ensuring constant contact of the pusher 3 with the valve 2, the pusher and valve are interconnected rigidly by means of an end piece 6 provided with a supporting washer 7, fixed in the end face of the delivery valve 2 and passing through an axial hole in the bottom of the pusher 3.

Above the end face of the delivery valve 2, on the end opposite to the pusher 3 is located a cavity 8 which communicates with a drain main 10 through a pipeline 9.

To utilize the energy of the liquid stream discharged to drain, the cavity 8 accommodates a piston 1 1, whose area is greater than that of the delivery valve 2. The piston 11 has an end piece or extension 12 which thrusts against theend face of the delivery valve 2. I

Above the piston ll is disposed an air cylinder 13 having a movable member 14 mounted coaxially with the valve 2. The movable member is a piston provided with a rod 15 and end piece 16 secured to its end surfaces. The end piece 16 serves for imparting the force exerted by the air cylinder 13 via the piston 11 to the delivery valve 2.

The cavity 4 between the valve 2 and pusher 3 communicates with a pump 18 via a high-pressure main 17, and with an actuating mechanism (not shown) via a pipeline 19.

The cavity 5 below the pusher 3 communicates with the high-pressure main 17 via a non-return valve 20, and with the drain main via a pipeline 21, a valve unit 22 and a throttle 23.

The valve unit 22 has a housing 24 and a movable element 25 therein disposed, defined as a cylinder, whose side surface provides, in combination with the housing 24, an annular chamber 26 communicating with the cavity 5 below the pusher.

The end surface of said movable element 25 forms, in combination with the housing 24, a chamber 27 communicating with the drain main 10 via the throttle 23.

The movable element 25 has an end piece 28 secured in its end face which is adapted to interact with the rod at the end of the opening stroke of the valve 2 in order to ensure its quick closing.

To ensure a quick lowering of the movable element 25, i.e., shutting off the

chambers

26 and 27, the element is loaded by a spring 29 whose force can be adjusted by a screw 30.

Due to the fact that the chamber 26, and hence the cavity 5 are leak-proof and that the cavity can communicate with the drain main 10 via a larger flow crosssection as the valve 2 is closed, the latter sizes can be relatively large, depending on the liquid flow rate.

The force exerted onto the delivery valve 2 and hence, the liquid pressure in the main 17 and in the other cavities under high pressure, is adjusted with the help of the air cylinder 13, which communicates with an air main 34 via an air distributor 31, non-retum valve 32 and a reducing valve 33.

The pulsator for hydraulic systems controlling actuating mechanisms operates as follows:

The pump 18 incorporated in the high-pressure main 17 is started. With no force exerted onto the piston 14, the cavities 4 and 8 are interconnected, allowing the liquid to flow freely into the drain main 10.

For placing the pulsator into operation, air from the air main 34 is admitted into the cylinder 13 via the reducing valve 33, non-return valve 32 and air distributor 31, thus exerting a force onto the piston 14 and delivery valve 2. The liquid starts flowing from the pump 18 into the cavity 4 to the actuating mechanism, and into the cavity 5 and chamber 26 via the non-retum valve 20.

As the resistance in the actuating mechanism starts building up, the pressure in the hydraulic system starts rising until it reaches a value corresponding to the force exerted on the valve 2 by the air cylinder l3.

As the pressure in the cavity 4 exceeds the force exerted by the air cylinder 13, the valve 2 opens slightly, due to which the excess pressure is relieved from the cavity 5, high-pressure main 17 and actuating mechanism. A pressure differential is produced between the cavities 4 and 5, determined by the liquid volume compressed in the cavity 5 and provided for by the nonreturn valve 20.

Due to the pressure difference and simultaneous actuation of the piston 11 by the liquid stream discharged to drain, the pusher 3 starts lifting the valve 2 until the total force developed below the pusher 3 and piston 11 and the force exerted onto the piston 14 of the air cylinder 13 become equal.

The movable element 25 is so disposed in the housing 24 that the clearance between its end piece 28 and the rod 15 is less than the possible opening stroke of the delivery valve 2. In this case, at the end of the stroke, the piston 14 actuates the end piece 28 with the aid of its rod 15 and opens slightly the movable element 25. A pressure of liquid is produced in the chamber 27 by means of the throttle 23, due to which the movable element 25 opens completely and provides communication between the

chambers

26 and 27.

During this time the pressure in the cavity 4, main 17 and the actuating mechanism will be completely relieved.

At the moment the movable element 25 of the valve unit 22 is raised, the valve 2 closes quickly, discharging the liquid from the cavity 5 with the help of the pusher 3 along the pipeline 21 into the drain main 10 via the

chambers

26, 27 and throttle 23.

Following the complete drain of the liquid from the cavity 5, the movable element 25, under the action of the spring 29 (whose tension is adjusted with the help of the screw 30) closes, and the cycle is repeated.

In this way the pressure is produced and relieved automatically, which results in a pulsating load in the actuating mechanism.

During the time the chamber 26 communicates with the drain main 10, the liquid from the main 17 is not supplied into the cavity 5 due to the pressure difference produced by the non-retum valve 20.

In order to overcome the forces caused by said pressure difference acting on the pusher 3 via the delivery valve 2, and to ensure a constant contact between the pusher 3 and the valve 2, a rigid interconnection is provided between the end piece 6 with the supporting washer 7.

The pressure in the hydraulic system is adjusted by means of the air cylinder l3 through the reducing valve 33. For convenient control of the pulsator, the valve 33 can be mounted, for example, on a control panel (not shown).

The time required for the movable parts of the pulsator to perform a cycle and hence, the liquid pulsation frequency, is adjusted by means of the throttle 23. Taking into account that at the instant the valve 2 opens the cavity 5 is rendered leak-proof, e.g., shut off from the drain main 10, the flow cross-section of the throttle I 23 can be taken in the present embodiment considerably larger, as compared with known pulsators, and be adjusted over a wide range.

Pilot samples of the pulsators executed according to the presentinvention have been mounted in hydraulic presses effecting to 500 t (ton force) pulsating loads and are undergoing experimental-industrial operation.

The oscillation frequency of actuating mechanisms (press plungers) constitutes to c.p.s. at an amplitude of up to 1 mm.

What is claimed is:

l. A pulsator for hydraulic systems controlling actuating mechanisms comprising: a housing; a delivery valve disposed in said housing; an air cylinder having a movable element and adapted for closing said valve, said air cylinder being disposed in said housing coaxially with said delivery valve at one of its ends; a pusher rigidly connected to said delivery valve disposed in said housing coaxially with said valve at its opposite end and serving for opening said delivery valve; a first cavity between said delivery valve and pusher, permanently communicating with a high-pressure main of the hydraulic system and with an actuating mechanism; a second cavity above the valve, communicating with a liquid drain main of the hydraulicsystem; a third cavity below said pusher; pipelines for connecting said third cavity to said high-pressure and drain mains, respectively; a non-return valve mounted on said pipeline connecting said third cavity to said high pressure main; a throttle mounted on said pipeline connecting the third cavity to said liquid drain main; a valve unit having a movable element mounted on said pipeline ahead of said throttle; the movable element of said valve unit serving to shut off said pipeline as said delivery valve is opened and to be actuated by the movable element of said air cylinder at the end of the delivery valve opening stroke in order to connect said pipeline to said liquid drain main as the delivery valve is closed.

2. The pulsator as claimed in claim 1, wherein said valve unit is provided with a housing and having disposed therein said movable element which is spring loaded and defined by a cylinder, whose side surface forms, in combination with the housing, an annular chamber communicating with the third cavity, while the end surface forms, in combination with the housing, a chamber communicating with the drain main, the movable element having an end surface, and an end piece mounted on the end surface for interacting with the movable element of the air cylinder.

3. The pulsator as claimed in claim 1, wherein a piston is accommodated in the second cavity the crosssectional area of the piston being somewhat larger than that of the delivery valve, the piston having end surfaces adapted to interact with the delivery valve and the movable element of the air cylinder, respectively.

Claims

1. A pulsator for hydraulic systems controlling actuating mechanisms comprising: a housing; a delivery valve disposed in said housing; an air cylinder having a movable element and adapted for closing said valve, said air cylinder being disposed in said housing coaxially with said delivery valve at one of its ends; a pusher rigidly connected to said delivery valve disposed in said housing coaxially with said valve at its opposite end and serving for opening said delivery valve; a first cavity between said delivery valve and pusher, permanently communicating with a high-pressure main of the hydraulic system and with an actuating mechanism; a second cavity above the valve, communicating with a liquid drain main of the hydraulic system; a third cavity below said pusher; pipelines for connecting said third cavity to said high-pressure and drain mains, respectively; a non-return valve mounted on said pipeline connecting said third cavity to said high pressure main; a throttle mounted on said pipeline connecting the third cavity to said liquid drain main; a valve unit having a movable element mounted on said pipeline ahead of said throttle; the movable element of said valve unit serving to shut off said pipeline as said delivery valve is opened and to be actuated by the movable element of said air cylinder at the end of the delivery valve opening stroke in order to connect said pipeline to said liquid drain main as the delivery valve is closed.

3. The pulsator as claimed in claim 1, wherein a piston is accommodated in the second cavity the cross-sectional area of the piston being somewhat larger than that of the delivery valve, the piston having end surfaces adapted to interact with the delivery valve and the movable element of the air cylinder, respectively.