RU55070U1 - ADJUSTABLE VALVE ADJUSTABLE - Google Patents

Abstract

The valve is designed for installation in volumetric hydraulic systems of various road-building, forestry, agricultural and other mobile machines. One of the types of pressure valves are overflow valves, which maintain a constant pressure of the liquid in the system by continuously draining (draining) part of the liquid into the tank. The overflow adjustable valve contains a locking element in the form of a cup with a conical and guide cylindrical surfaces, which has the possibility of axial movement due to the spring installed with a gap in its internal bore, and it is preloaded by means of an adjustment screw. The presence of flats on the outer surface of the locking element with the formation of through windows allows throttling of the liquid at the initial stage of valve opening. Due to this, the delay in valve opening decreases with a sudden increase in flow. With a sharp increase in pressure in the hydraulic system due to the small mass of the shut-off element and low friction force, a quick release of critical pressure occurs. The presence of an axial throttle hole in the bottom of the shut-off element serves to by-pass excess working fluid in the flow control mode. This allows damping of the vibrational energy and thereby reduce resonant vibrations.

Description

The valve is designed for installation in volumetric hydraulic systems of various road-building, forestry, agricultural and other mobile machines.

One of the types of pressure valves are overflow valves, which maintain a constant pressure of the liquid in the system by continuously draining (draining) part of the liquid into the tank.

Known overflow valve having a tapered locking element, the degree of opening of which is regulated by a spring (Hydraulics, hydraulic machines and hydraulic actuators under the editorship of TM Bashty, - M: Mechanical Engineering, 1970, p. 429-436; Sveshnikov V.N., Usov AA Machine-tool hydraulic drives: Handbook - 2nd ed., Revised and enlarged - M .: Mashinostroenie, 1988, - p. 117).

With this arrangement of the pressure valve, the shut-off element has a large mass and linear dimensions, and therefore, increased friction forces, which entails an increase in the requirements for the geometric parameters of the mating parts and an increase in the response time.

Known hydraulic safety valve (AS No. 280138, published 10.11.1995 in bull. No. 31) containing a conical locking element with a hollow piston, which is installed in the cavity of a large piston and is equipped with a spring. A throttle hole is made in the housing of the large piston. The spring preload is adjusted with a lock nut.

The disadvantage of this valve is that the diameter of the shut-off element increases depending on the increase in pressure of the flow of the working fluid. This in turn leads to an increase in overall dimensions, and hence an increase in valve mass. The presence of a large number of mating parts complicates its manufacture.

The closest device of the same purpose, which is adopted as a prototype, is a bypass valve (RF, Patent No. 2116542, published on July 27, 1998 in Bull. No. 21) containing a housing with inlet and outlet openings, a saddle between these openings, a cylindrical cavity with an external conical locking element made with radial holes, and a spring. An internal locking element is installed in the bore of the locking element in the form of a slide valve, the axial movement of which is regulated by an additional spring.

The disadvantage of this valve is that it is structurally complex, as it has two locking elements, adjustable by two springs or a spring unit. The inability to adjust the load of the springs complicates the calculation of their stiffness.

The throttle channel connecting the valve region with the control pressure hydraulic line complicates the design of the hydraulic system due to the implementation of additional pipelines.

The technical problem to which this invention is directed is to expand the arsenal of overflow valves by increasing the reliability of operation by reducing resonant oscillations and response time. This provides a quick release of critical pressure with a stable value of the required residual pressure. In addition, simplification of the design leads to a decrease in the size and weight of the valve.

The specified technical problem is solved in common with the prototype by the presence of a locking element in the form of a cup with a conical and guide cylindrical surfaces, which has the possibility of axial movement due to the spring installed with a gap in its internal bore, and it is preloaded by means of an adjusting screw.

To achieve this result, at least three flats with the formation of through windows are made on the outer surface of the locking element. This allows at the initial stage of opening the valve to throttle the liquid through the slotted channels of the opening windows and then through the gaps between the turns of the spring to drain. Due to this, the delay in valve opening decreases with a sudden increase in flow.

With a sharp increase in pressure due to the small mass of the locking element, and hence the low friction force, there is a sharp compression of the spring and fluid in the valve region, which is under residual pressure. The throttling of the working fluid through the small gaps of the coil of the spring, slows down the movement of the locking element and the rapid release of critical pressure through the slotted channels of the windows into the drain line.

The presence of an axial throttle hole in the bottom of the shut-off element serves to by-pass excess working fluid in the flow control mode. This allows damping the vibrational energy and thereby reduce resonance vibrations in the hydraulic system.

Figure 1 is a General view of the valve in the drain section of the valve (longitudinal section);

Figure 2 is a section aa (figure 1);

Figure 3 - locking element (in a three-dimensional image).

In the housing 1 of the drain section of the hydrodistributor (Fig. 1) there is a locking element 2 made in the form of a cup with a cylindrical guide 3 and a conical locking 4 outer surfaces, the last of which abuts against the edge of the saddle 5. On the outer surface of the locking element flats 6 are made (Fig. 3), with the formation of through windows 7 (Fig.1, 3). The length of the flats is selected from the conditions of rigidity of the locking element and the distance from the edge of the saddle 5 to the drain channel 8 (Fig.1, 2). A throttle hole 9 is made in the bottom of the locking element for damping resonant vibrations, which connects the valve region 10 to the overflow channel 11. To reduce the mass of the locking element, a blind hole 12 is made. The spring 13 is installed with one end in the inner bore 14 of the locking element with a gap along its diameter. The other end of the spring 13 is installed in the bore of the plug 15 and abuts against the adjusting screw 16 with its end. The tightness of the connection of the plug 15 with the housing 1 provides an o-ring 17.

Overflow adjustable valve operates as follows.

Before starting work, the load of the spring 13 is set using the adjusting screw 16 at the working pressure in the hydraulic system. In the initial state, the conical part 4 of the locking element under the influence of the spring 13 is in close contact with the edge of the seat 5 and the valve is in the closed state.

When the working fluid is supplied to the overflow channel 11, it enters the valve cavity 10 through the throttle opening 9 and, passing between the turns of the spring 13, passes through the window 7 through the drain channel 8 into the tank. Since the cross section of the throttle aperture 9 is small, the pressure in the channel 11 continues to increase to the value necessary for the control system to work, as well as to a value sufficient to overcome the force of the spring 13. When the pressure reaches the required value, the shut-off element 2 moves away, and the working fluid opens slotted channels 18 (figure 2) goes into the channel 8 and then to drain. Since the diameter of the spring 13 is less than the diameter of the inner bore 14, all slotted channels 18 are involved.

When reducing the pressure in the overflow channel 11 to a value less than the value necessary to overcome the total pressure of the spring and the residual pressure, the locking element 2 under the influence of the spring 13 sits on the saddle 5, providing separation of the channels 8 and 11.

With a sharp increase in pressure in the channel 11, the locking element 2 due to the small mass and small friction forces opens almost instantly, compressing the spring 13 and the working fluid in the valve cavity 10, which is under residual pressure. The working fluid begins to flow between the coils of the spring, through the windows 7

into channel 8 and on to the drain. Since the gap between the turns of the spring is reduced, there is a throttling of the liquid and the slowing down of the movement of the locking element, and the slowing speed is proportional to the movement of the locking element. In this case, the working fluid continues to flow through the slotted channels 18 into the drain channel 8, which leads to a rapid release of critical pressure in the system.

Claims (1)

An adjustable overflow valve containing a locking element in the form of a cup with a conical and directing cylindrical outer surfaces and a stepped inner bore, relative to the wall of which a spring is installed with a gap, previously loaded with an adjusting screw, characterized in that flats are made on the outer surface of the locking element, with the formation through windows, and at the bottom of the locking element made an axial throttle hole.