RU2334906C1 - Multi-purpose valve - Google Patents

Abstract

FIELD: mechanics.

SUBSTANCE: invention related to hydraulic hardware and is designed to smoothly adjust working fluid for rate. The multi-purpose valve shutoff-and-governor element cylindrical guide part diameter is smaller than that of the element cylindrical sealing collar. The diameter of the aforesaid element upper stem located in the valve pot is smaller than that of the lower stem located on the valve outlet. The said diameters in the entire range of pressures in the valve outlet channel satisfy the terms of the specified set of inequalities.

EFFECT: higher reliability hermetic valve orifice size closing under abnormal conditions and higher accuracy in working fluid flow rate control over the entire valve orifice size variation range.

2 cl, 2 dwg

Description

The invention relates to the field of hydraulic equipment, namely to pressure shut-off and control valves, that is, valves designed to smoothly control the flow of working fluid in the area between the high-pressure power source and the hydraulic motor from zero (when the valve cross-section is completely blocked) to the corresponding maximum ( when opening the valve cross section to the maximum value), and can be used, in particular, in hydraulic actuators for forging and stamping presses.

Known shut-off valve containing a housing with connecting inlet and outlet channels, in the bore of which is made a saddle with a sealing chamfer and a central cylindrical sealing girdle having a diameter not larger than the inner diameter of the sealing chamfer of the saddle, and a bore and a locking-regulating element with coaxial guide with a cylindrical part, a collar with a locking chamfer, a reciprocal cylindrical sealing girdle and a shank associated with two diametrically located rods whose ends through the sealed openings extend in opposite directions beyond the valve body, while the valve body is hermetically sealed with a cover located in relation to the locking and regulating element from the side opposite the valve seat, and the locking and regulating element is installed to form from its side a shoulder of the inlet cavity connected to the connecting inlet channel of the valve, with the formation between the surfaces of the shank of the locking-regulating element and the Central hole of the channel seat, with union with the connecting outlet valve channel, and to form between the surfaces of the shutoff member and the cavity cover supravalvular [1].

In said shut-off and control valve, the supra-valve cavity is connected to the connecting inlet channel by means of a throttle hole, and the shut-off and control element is provided with an axial hole and a discharge cavity with a discharge valve seat, the shutter of which is located in the discharge cavity and is rigidly connected to the rods located in the axial hole -regulating element and equipped with longitudinal recesses and a protrusion forming the stop of the locking-regulating element from the side opposite the saddle of the unloading valve and, in this case, the discharge cavity is communicated with the supravalve cavity and, through the seat of the discharge valve and longitudinal recesses, with the outlet channel. The shank of the locking and regulating element is made conical and directed by the apex of the cone towards the outlet channel, and the guiding cylindrical part of the locking and regulating element has a diameter not less than the largest diameter of the conical shaft equal to the diameter of the cylindrical sealing girdle.

In the design under consideration, the upper (located on the side of the supravalvular cavity) and lower (located on the side of the valve outlet channel) rods are connected with the locking and regulating element with the possibility of axial movement relative to it by a gap equal to the stroke of the shutter of the discharge valve relative to the locking and regulating element , and have the same diameters.

In the absence of a control signal for opening the valve in question, its locking-regulating element is pressed against the saddle by the resulting pressure force of the liquid. Since this force can be quite significant, to exclude the destruction of the sealing facet of the saddle and the locking facet of the locking-regulating element (due to high contact stresses), the surface area of their contact should have a value not less than a certain limiting value. Limiting the size of the specified area to a minimum determines the complication of grinding in the sealing facet of the seat and the locking facet of the locking and regulating element to a state in which the tightness of the specified pair is ensured.

To reduce the effort required by the control actuator of the shut-off and control valve, an unloading valve is provided (the output link of the control actuator is connected to one of the rods rigidly connected to the shutter of the unloading valve).

The presence of an unloading valve located in the inner cavity of the shut-off-control element complicates the design of the known shut-off-control valve and reduces the reliability of its operation due to the possible leakage of an additional valve pair: shutter-seat of the unloading valve.

The presence of two valve pairs in the structure under consideration (both of which require lapping) complicates the manufacture of the valve and its repair work during operation.

When operating this valve (especially on contaminated working fluids), the throttle hole may be eroded (increased in diameter), by means of which the supravalve cavity is connected to the connecting inlet channel. Due to this, when the discharge valve cross-section is opened until the stop of the lock protrusion in the locking-regulating element, the pressure loss at the throttle bore, ceteris paribus, is lower, the pressure in the supravalve cavity is higher, and the force required to lift the locking-regulating element relative to its seat , more, which determines the need to overestimate the required effort of the control valve actuator at the stage of its manufacture (with a corresponding increase in dimensions and mass of the actuator).

With a small opening of the passage section between the locking chamfer of the locking-regulating element and the sealing chamfer of its seat (after the stop of the protrusion of the shutter of the discharge valve in the locking-regulating element), when the passage section between the cylindrical sealing belts of the locking and regulating element is not yet open or open and saddles, the pressure in the space between the locking and regulating element and the saddle in the area limited by the specified cylindrical sealing bands and the entrance to the gap between the locking chamfer of the locking-regulating element and the sealing chamfer of the seat, rises to a value equal to or close to the pressure in the inlet of the valve. In this regard, if the diameter of the guide cylindrical part of the locking and regulating element is larger (which is one of two possible interpretations of the concept of "not less than") the largest diameter of the conical shank, which is equal to the diameter of the cylindrical sealing belt of the locking and regulating element, then the hydraulic clamp the regulating element to the protrusion of the shutter of the discharge valve is not guaranteed and under the influence of the changed balance of the forces of the liquid pressure, an uncontrolled displacement of the locking-regulating valve is possible element in the direction from its seat, reducing the mismatch between the movements of the shutter of the discharge valve and the locking-regulating element. This entails a decrease in the area of the passage section of the discharge valve and an increase in pressure in the supravalvular cavity, which, in turn, leads to the movement of the locking and regulating element in the opposite direction and so on.

Thus, with small openings of the valve cross-section, longitudinal oscillations of the locking-regulating element cannot be ruled out, accompanied by uncontrolled changes in the area of the valve’s flow-through section and, accordingly, the flow rate of the working fluid through it, blows of the locking-regulating element along the valve protrusion and the locking chamfer of the discharge valve, and as a result this increased noise and valve wear, which reduces the reliability of the valve.

The installation of rods rigidly connected with the shutter of the discharge valve with an axial clearance relative to the locking element (equal to the stroke of the discharge valve with respect to the locking element), firstly, creates the conditions for uncontrolled movements (oscillations) of this element relative to the rods, and secondly, leads to loss of time for sampling the specified gap and to the movement of the locking and regulating element relative to its saddle with delay in relation to the moment of the start of regulation, which reduces valve performance when it is opened.

When the valve cross section is open and the pressure drop in its inlet and outlet channels is small, the resulting pressure force acting from the working fluid on the valve of the discharge valve with rods and a shut-off and control element for the shut-off-control valve in question (due to the fact that the guide the cylindrical part of the locking and regulating element has a diameter not less than the largest diameter of the conical shank, and the diameters of the upper and lower rods are the same) may matter, not enough chnoe to overcome friction forces in pairs and move movable valve and discharge valve respectively, locking and regulating member to a position wherein the valve passage section is closed. Therefore, if the connection between the corresponding rod and the output link of the control valve actuator fails or the specified drive fails, the shutter of the discharge valve and the locking and regulating element may remain in a position where the valve bore is open, which is not permissible for safety reasons, as it is accompanied by the movement of the output link of the hydraulic motor and the work equipment they bring and may lead to an emergency. This circumstance (insufficient reliability of closing the bore in emergency situations) is the main disadvantage of the known shut-off and control valve.

One of the ways to ensure reliable closure of the valve bore in emergency situations is to use a spring in its design, the preload force of which acts in the direction of closing the valve bore and is sufficient to carry out this operation. However, the introduction of such a spring into the valve structure complicates its design.

When executing the shank of the locking and regulating element with a conical lateral surface, the law of changing the area A _{r · о · cl of the} passage section of the working window opened by the locking and regulating element after it is raised relative to the saddle by the amount of overlap of the sealing cylindrical belts, as a function of its further movement x relative to the saddle (neglecting the value of the radial clearance between the cylindrical sealing belts of the locking-regulating element and its saddle) has the form:

A _r.o.cl = π (D _n -0.5x sin2α) x sinα,

where D _n is the diameter of the cylindrical sealing strip;

α is the half angle at the apex of the conical lateral surface of the shank.

Since the magnitude of 0,5x · sin2α is sufficiently small compared with the diameter D _n (especially for small values of x), then the said law is close to linear. In the case of a linear law, the change in the area of the valve passageway from the movement of its locking and regulating element, as is known, the relative error in regulating the flow of the working fluid with a fixed error in installing the locking and regulating element in the required position and other conditions being equal very much depends on the value of x and theoretically increases on hyperbolic dependence with decreasing x (see: Goydo ME Hydraulic equipment with proportional electric control: Textbook. - 2nd ed., p rerab and extra - Chelyabinsk. Univ. of South Ural State University, 2000. - S.27-28).

Thus, the existing shut-off and control valve is characterized by low accuracy of flow control in the area of small openings by the shut-off and control element of the passage section, which is also its significant drawback.

The closest in technical essence to the claimed object is a shut-off and control valve adopted as a prototype, comprising a body with connecting inlet and outlet channels, in the bore of which there is a saddle with a sealing chamfer and a central cylindrical sealing girdle having a diameter not larger than the inner diameter of the sealing chamfer saddles, and a bore and placed a locking-regulating element with a coaxial guide cylindrical part, a collar with a locking chamfer, a response cylinder a single sealing girdle and a shank connected to two diametrically located rods, the ends of which through the sealed holes extend in opposite directions outside the valve body, while the valve body is hermetically closed by a cover located in relation to the locking and regulating element from the side opposite the valve seat, and the locking-regulating element is installed with the formation on the side of its collar of the input cavity connected to the connecting input channel of the valve, with the formation between by the properties of the shank of the locking-regulating element and the central hole of the channel seat connected to the connecting outlet channel of the valve, and with the formation between the surfaces of the locking-regulating element and the cover of the valvular cavity in communication with the connecting output channel [2, Figs. 4, 5]. At the indicated valve, the upper (located on the side of the valve valve cavity) and lower (located on the side of the valve outlet channel) rods (the output link of the control actuator is connected to one of these rods) are axially fixed relative to the locking-regulating element and have the same diameters, and the effective the surface areas involved in the transfer of force from the working fluid to the locking and regulating element have values that ensure complete or almost complete unloading of the locking and regulating element uyuschego element hydrostatic forces from fluid pressure.

Due to the almost complete unloading of the locking and regulating element of the known valve from the hydrostatic pressure of the fluid, the contact stresses necessary in the contact zone of the seat sealing facet and the locking facet of the locking and regulating element are created by means of a valve actuator to ensure a tight separation of the input and output cavities of the valve. If the connection of the corresponding rod of the locking-regulating element with the output link of the valve control actuator is broken or the specified drive fails, contact stresses in the contact zone of the seat sealing facet and the locking facet of the locking-regulating element decrease and the valve tightness is broken.

When the valve cross section is open, the resulting pressure force acting from the working fluid side on its locking and regulating element (due to the almost complete unloading of the locking and regulating element of the valve under consideration from the hydrostatic pressure of the liquid) may not be sufficient to overcome the friction forces in moving pairs and moving the locking and regulating element to a position where the valve bore is closed (moreover, this force can act in the direction of opening ohodnogo valve section). Therefore, if the connection between the corresponding rod and the output link of the valve control actuator fails or the specified drive fails, the shut-off and control element may remain in a position in which the valve bore is open, which is not permissible for safety reasons, since it is accompanied by the movement of the output link of the hydraulic motor and the operating equipment and may lead to an emergency. This circumstance (insufficient reliability of the hermetic closure of the bore in emergency situations) is the main disadvantage of the known shut-off and control valve.

The central bore of the valve seat in the section between the sealing chamfer and the central cylindrical sealing girdle has a conical surface (with the apex of the cone directed towards the outlet channel). An adjustable valve cross section is formed between the specified conical surface of the seat and the lower edge of the mating cylindrical sealing girdle made on the shank of the locking and regulating element from the side of the valve outlet channel. At the same time, the law of changing the area A of the _{r.o.cl. of the} passage section of the working window opened by the locking-regulating element after it is raised relative to the saddle by the amount of overlap of the sealing cylindrical belts is close to linear in the function of its further movement x relative to the saddle. In the case of a linear law, the change in the area of the valve passageway from the movement of its locking and regulating element, as already noted above, the relative error in regulating the flow of the working fluid with a fixed error in installing the locking and regulating element in the required position and other conditions being equal, very significantly depends on the value of x and theoretically increases in hyperbolic dependence with decreasing x.

Thus, the shut-off and control valve in question is characterized by low accuracy of flow control in the area of small openings by the shut-off and control element of the passage section, which is also its significant drawback.

In addition, since the maximum passage area of the valve is determined by the area of the ring, the larger (outer) diameter of which is equal to the diameter of the central cylindrical sealing girdle of the seat, and the smaller (inner) diameter is equal to the diameter of the lower stem of the locking and regulating element, the execution of the central passage of the seat in the section between the sealing chamfer and the central cylindrical sealing girdle with a conical surface (with the top of the cone directed towards the outlet channel) with the rest x equal conditions entails the need to increase the diameter of the seat and the transverse dimensions of the valve as a whole, which is irrational.

The technical problem solved by the invention is the creation of a shut-off and control valve, characterized by increased reliability of hermetic closure of its bore in emergency situations (for example, if the rod of the shut-off-control element is broken from the output link of the valve control actuator), due to the appropriate choice of the ratio of the geometrical sizes of the shut-off valve -regulating element (from the condition of ensuring the constant action of the resulting fluid pressure force on the locking-regulating element nt in the direction of the seat).

Another technical objective of the invention is the creation of a shut-off and control valve, characterized by high accuracy of regulating the flow of working fluid in the entire range of changes in the area of the valve bore due to special profiling of the lateral surface of the shank of the shut-off and control element (from the condition of obtaining an equal percentage control characteristic of the valve).

To solve the technical problem in the known shut-off and control valve, comprising a housing with connecting inlet and outlet channels, in the bore of which a seat is made with a sealing chamfer and a central cylindrical sealing girdle having a diameter not larger than the inner diameter of the sealing chamfer of the saddle and a bore and a locking and regulating element with a coaxial guide cylindrical part, a collar with a locking chamfer, a reciprocal cylindrical sealing belt and a tail associated with two diametrically located rods, the ends of which through the sealed openings extend in opposite directions outside the valve body, while the valve body is hermetically closed by a cover located in relation to the locking and regulating element from the side opposite the valve seat, and the locking and regulating element installed with the formation on the side of its shoulder of the input cavity connected to the connecting input channel of the valve, with the formation between the surfaces of the shank of the locking-regulating according to the invention, the diameter of the guide cylindrical part of the shut-off and control element is made smaller than the diameter of its cylindrical sealing element and the central bore of the seat of the channel connected to the connecting outlet channel of the valve, and with the formation between the surfaces of the locking-regulating element and the cover of the valvular cavity in communication with the connecting output channel girdle, and the diameter of the upper rod of the locking-regulating element located on the side of the supravalvular cavity is made smaller e lower stem diameter, located on the side of the valve outlet and said diameter throughout the possible range of values of pressure in the outlet channel of the valve system satisfy the following inequalities:

where D _n - the diameter of the guide cylindrical part of the locking and regulating element;

d _kn , D _kv - respectively the outer and inner diameters of the contact surface of the locking chamfer of the locking-regulating element and the sealing chamfer of the saddle;

d _sh.n , d _sh.v - diameters of the lower and upper rods of the locking and regulating element, respectively;

D _pz - the diameter of the cylindrical sealing belt locking element;

R _pit - constant pressure (supply pressure) in the valve inlet channel;

p - pressure in the outlet channel of the valve (0≤p≤p _pit );

σ _min , σ _max are the values of the minimum (from the condition of tightness) and maximum (from the condition of strength) allowable stresses on the contact surface of the locking facet of the locking-regulating element and the sealing facet of the saddle (σ _min > p _pit );

R is the force that must be applied to the locking and regulating element in order to move it in the direction of the saddle until it contacts it from the position at which the valve cross-section is open.

According to the invention, the lateral surface of the shank of the locking element is profiled on the basis of the following equation establishing the relationship between the current required value of the diameter D _{z of the} shaft and the coordinate z, measured along the axis of the shaft from the plane of its junction with the cylindrical sealing belt of the locking element:

where D _{P. c} is the diameter of the Central cylindrical sealing belt of the saddle;

D _z - the current required value of the diameter of the shank;

z is the coordinate measured along the axis of the shank from the plane of its junction with the cylindrical sealing belt of the locking and regulating element;

A ₀ is the initial value of the cross-sectional area between the shank of the locking and regulating element and the central cylindrical sealing girdle of the saddle, equal to the area of the ring, the outer diameter of which is equal to the diameter of the sealing girdle of the saddle, and the inner diameter is the diameter of the cylindrical sealing girdle of the locking and regulating element;

δ is the allowable value of the relative error in the regulation of the flow rate of the working fluid;

Δ is the maximum absolute value of the error in the installation of the locking and regulating element of the valve in the desired position.

The diameter of the guide cylindrical part of the locking and regulating element is less than the diameter of its cylindrical sealing girdle, and the diameter of the upper rod of the locking and regulating element located on the side of the supravalve cavity is smaller than the diameter of the lower rod located on the side of the valve outlet channel, predetermines at any value of the pressure in the output the valve channel from a range from zero to the pressure in the valve inlet channel (supply pressure) the action of the resulting hydrostatic force the pressure of the working fluid on the locking and regulating element in the direction of the saddle of the locking and regulating element, that is, in the direction of closing its bore, and thereby creates the prerequisites for closing the bore of the valve and ensuring a tight separation of its inlet and outlet channels in emergency situations (for example, in case of communication failure of the rod of the locking-regulating element with the output link of the valve control actuator).

The latter position is confirmed by the following calculations below.

With a closed passage section of the valve (in the presence of a contact of the locking chamfer of the locking-regulating element and the sealing facet of the seat), the resulting force P _{is the} hydrostatic pressure of the working fluid on the locking-regulating element pressing it to the saddle, obviously, is:

Since according to the present invention, D _n <D _n.z and, by default, D _n.z <D _KV <D _KN, then obviously the inequality: D _n <D _KN - and the amount of force F _engraft at p = 0

is strictly positive.

According to the expression (4), the value of _Pzh linearly depends on the pressure p with the proportionality coefficient B:

At B = 0, the value of P _{prig is} practically independent of the pressure p and, at any value, remains constant and equal to P _prig . ₀ .

At B> 0, the value of P _cri with an increase in the value of pressure p from zero to P _num increases in comparison with the value of P _{cf 0} and, therefore, it is always always positive.

At B <0, the value of P _{creep decreases} with an increase in pressure p from zero to p _num in comparison with the value of P _cc . ₀ .

However, since when p = p _num in accordance with the expression (4), the value of P _prizh for any value of B takes the value of P _prizh.red :

and according to the invention D _sh.v <D _sh.n , then even at B <0 and p = p _{pit the} value of P _hold remains substantially positive, which was to be proved.

In the absence of contact between the locking chamfer of the locking-regulating element and the sealing chamfer of the seat in the first approximation (when, in particular, neglecting the additional force of the working fluid on the locking-regulating element associated with a change in the momentum of the liquid when it passes through the open locking the regulating element is the passage section) the force P _closed acting on the side of the working fluid on the locking-regulating element and directed towards its saddle can be represented with as follows:

Since in accordance with the invention D _n <D _n.s. , the magnitude of the force P _close at p = 0

is strictly positive.

According to the expression (8), the value of P _close linearly depends on the pressure p with the proportionality coefficient C:

Since D _n.s. <D _q.v , then obviously C> B and, in particular, when B = 0, the value of C is necessarily positive.

At C = 0, the value of P _close practically does not depend on the pressure p and for any of its value remains constant and equal to P _{close 0} .

When C> 0, the value of P _close with increasing pressure p from zero to P _pit increases compared to the value of P _{close 0} and, therefore, it is obviously always positive.

When C <0, the value of P _close with increasing pressure p from zero to P _num decreases compared with the value of P _{close 0} .

However, since at p = p _num, in accordance with expression (8), the value of P _close at any value of C takes the value of P _close :

and according to the invention D _sh.v <D _sh.n , then even with C <0 and p = p _{num, the} value of P _close remains substantially positive, as indicated above.

The diameters of the guide cylindrical part, the cylindrical sealing girdle, the upper and lower rods of the locking and regulating element in such a way that these diameters, in addition to satisfying the relations formulated earlier, also in the entire possible range of pressure values in the valve outlet channel satisfy the system inequalities (1), (2), even with a malfunction of the control valve actuator provides: firstly, with a closed passage section of the valve, creating on the contact surface second shut-off bevel regulating member and the sealing seat chamfers stresses sufficient to ensure a hermetic separation of the inlet and outlet valve ports and, at the same time does not exceed the value of the stress, the permissible strength of the conditions of the contacting surfaces [see. inequality (1)]; secondly, when the valve’s cross-section is open, the action on the locking and regulating element from the working fluid side is greater than the corresponding resistance forces and sufficient to move the locking and regulating element in the direction of the seat until it touches [see inequality (2)].

Thus, the implementation of the present invention guarantees increased reliability of hermetic closure of the bore of the shutoff-regulating valve in emergency situations (for example, if the rod of the shut-off-regulating element is not connected with the output link of the valve control actuator).

It should be noted that when assigning the value of the maximum allowable stress σ _max on the contact surface of the locking chamfer of the locking-regulating element and the sealing facet of the seat, it should be taken into account that, with a functioning valve control valve, it provides an additional force that presses the locking-regulating valve when the valve cross section is closed element to the seat (i.e., σ _max value must be appropriately underestimated compared to the maximum possible value for the contact stress spolzuemyh material components).

Since with increasing pressure p in the valve outlet channel from zero to p _num, an increase in contact stresses σ between the locking facet of the locking-regulating element and the sealing facet of the seat:

doesn’t make sense [since the pressure drop (p _num - p) on the sealing section decreases with increasing pressure p], it is advisable when designing the shut-off and control valve to a first approximation to proceed from the condition that the following [more "rigid" in comparison with the inequality (1)] ratios:

Based on the expressions (12), (13) and (14), we obtain the following formula for determining the required diameter D _{n of the} guide cylindrical part of the locking-regulating element:

[diameters D _{K. n} and D _K. in a first approximation are selected using the relation (22) below based on information about the required diameter of the nominal passage of the shut-off and control valve].

Having excluded the value of D _n from relation (13) using formula (15), we arrive at the following expression establishing the relationship between the diameters of O ² _sh.n and D _sh.

Since D _Ш.н > D _ш.в , it is advisable to use the lower stem of the locking-regulating element for communication with the output link of the valve control actuator. At the same time, this rod is power and its diameter D _Ш.н must satisfy the requirements arising from the conditions of strength and longitudinal stability of the rod. On the other hand, the diameter D _{Ш. in the} upper rod of the locking-regulating element cannot be negative, and when using the upper rod to control the current position of the locking-regulating element cannot be less than a certain value, which is usually assigned for design reasons. These additional conditions together with the expression (16) make it possible to calculate the specific required values of the diameters D _{W. n} and D _W.

If relation (13) is fulfilled, which is equivalent to equality: B = 0 [see expression (6)], the inequality is automatically satisfied:

which corresponds to the inequality: C> 0 [see expression (10)].

In this case, as mentioned above, the magnitude of the force F _CLOSE exerted by the working fluid on the locking and regulating member toward its seat, with increasing pressure values p from zero to p _num increases, and therefore, if inequality (2) holds for p = 0, then it is performed in the entire range of pressure values p from zero to p _num . In this regard, to ensure the closure of the valve bore under the action of the working fluid, instead of inequality (2), it is sufficient to fulfill the inequality:

which implies

or taking into account the expression (15)

Since the default should be performed D _PZ inequality <D _q , then on the basis of it and inequality (20) we obtain the following inequality:

from which we determine the required ratio between the diameters D _{K. n} and D _K. in the initial stage of their selection:

The diameters obtained as a result of the calculation must be rounded and refined (taking into account a number of normal diameters of the moving sealing cylindrical pairs, the range of seals used, etc.) and, ultimately, in the entire possible range of pressure values in the valve outlet channel must satisfy the system inequalities (1) and (2).

The implementation of the profile of the lateral surface of the shank of the locking-regulating element on the basis of equation (3) provides high accuracy of regulating the flow rate of the working fluid through the valve in the entire range of changes in the area of its bore.

In order for the relative error in regulating the flow rate of the working fluid, caused by the error in installing the locking and regulating element in the required position, for a fixed absolute value of the maximum value Δ of this error and other conditions being equal, not exceeding the absolute value of the predetermined allowable value δ, it is necessary that the area connection And _{p.0 is the} passage section of the working window that is opened by the locking-regulating element, with its movement y in the direction of opening the passage section of the valve o regarding the position at which the edge of the cylindrical sealing girdle of the saddle, closest to the sealing chamfer of the latter, is located in the plane of the junction of the shank and the cylindrical sealing girdle of the locking-regulating element, had the form (see: Goydo M.E. Hydraulic equipment with proportional electric control: Training manual . - 2nd ed., Revised and additional - Chelyabinsk: Publishing house of SUSU, 2000. - P.29):

For the valve in question, the passage section that is determined from the point of view of its adjustment characteristic, which is opened by the locking-regulating element, is the lateral surface of the truncated cone formed by the normals to the lateral profiled surface of the shank of the locking-regulating element, drawn from the points of the edge of the cylindrical sealing girdle of the seat close to the sealing facet of the latter.

For each value of displacement y normals intersect said lateral profiled surface shank shut-regulating member at a distance z from the joint plane of the shank with a cylindrical sealing belt locking and regulating member, wherein the shank has a diameter value D _z.

In view of the foregoing, the following relationships are true:

(here β _z - angle complementary to the value of 180 ° angle of inclination of the tangent to the side of the profiled surface of the shank at a point situated at a distance z from the shank joint plane with a cylindrical sealing belt locking and regulating member and lying, respectively, on a circle with diameter D _z , relative to the axis of the shank in the reference direction of the coordinate z).

Equating the left-hand sides of expressions (23) and (24) taking into account relations (25), (26) and taking into account the fact that

cosβ _z = (1 + tgβ _z ) ^{l / 2} ,

we get

The last equation (27), which establishes the relationship between the current required value of the shank diameter D _z and the coordinate z, counted along the axis of the shank from the plane of its junction with the cylindrical sealing belt of the locking-regulating element, completely coincides with equation (3).

And since equation (27) is obtained on the basis of relation (23), the identity of equations (27) and (3) proves the above statement that when performing the profile of the lateral surface of the shank of the locking-regulating element on the basis of equation (3), a high (with a relative error not exceeding a predetermined allowable value δ) the accuracy of regulation of the flow rate of the working fluid through the valve in the entire range of changes in the area of its flow area.

The invention is illustrated by drawings, where figure 1 shows a structural diagram of a shut-off and control valve, figure 2 is a design diagram for determining the area of the passage section of the valve.

Shut-off and control valve (figure 1) contains a housing 1 with connecting input 2 and output 3 channels. In the bore of the housing 1, coaxial saddle 4 is fixedly mounted with a sealing chamfer 5 and a central cylindrical sealing girdle 6 having a diameter not larger than the inner diameter of the sealing chamfer 5 of the saddle 4, and a bore 7 and a guide sleeve 8 with holes 9 from the input channel 2 side. In the guide sleeve 8 there is a locking-regulating element 10 with a coaxial guide cylindrical part 11, a collar 12 with a locking chamfer 13, a reciprocal cylindrical sealing girdle 14 and a shank 15, made with two diameters spaced upper 16 and lower 17 rods. When the locking chamfer 13 of the locking and regulating element 10 and the sealing facet 5 of the seat 4 are in contact, the counter cylindrical sealing girdle 14 of the locking and regulating element 10 forms a spool pair with a guaranteed radial clearance and positive overlap with the central cylindrical sealing belt 6 of the saddle 4. The housing 1 is hermetically closed by a cover 18, located in relation to the locking and regulating element 10 from the side opposite to the valve seat 4. The locking and regulating element 10 is installed with the formation on the side of its collar 12 of the input cavity 19, connected through holes 9 made in the guide sleeve 8, with the connecting input channel 2 of the valve, with the formation between the side surface 20 of the shank 15 of the locking element 10 and the surface the Central passage 7 of the seat 4 of the channel 21, connected to the connecting output channel 3 of the valve, and with the formation between the surfaces of the locking and regulating element 10 and the cover 18 nadklapanny cavity 2 2 communicated through an opening 23 made in the locking-regulating element 10, with a connecting output channel 3.

The ends of the upper stem 16, located on the side of the overvalve cavity 22, and the lower stem 17, located on the side of the outlet channel 3 of the valve, through the corresponding sealed holes made in the cover 18 and the housing 1, go beyond the valve body 1 into the atmosphere.

The contact surface of the guide cylindrical part 11 of the locking and regulating element 10 and the guide sleeve 8 is sealed by means of a seal 24, which prevents the fluid from flowing over the radial clearance between parts 10 and 8 of their valve inlet cavity 19 into its valve body 22.

The diameter D _{n of the} guide cylindrical part 11 of the locking and regulating element 10 is made smaller than the diameter D of the _{item c of} its cylindrical sealing girdle 14, and the diameter D _{W. in the} upper rod 16 of the locking and regulating element 10 is made smaller than the diameter D of the _connecting rod of the lower rod 17, and the indicated diameters in the entire possible range of pressure values in the outlet channel 3 of the valve satisfy the system of inequalities (1) and (2).

The lateral surface 20 of the shank 15 of the locking and regulating element 10 is profiled based on equation (3), which establishes the relationship between the current required value of the diameter D _{z of the} shank 15 and the coordinate z, measured along the axis of the shank 15 from the plane of its junction with the cylindrical sealing girdle 14 of the locking and regulating element 10 (figure 2).

The lower stem 17 of the locking and regulating element 10 is a control (power) and is connected (preferably without a gap in the axial direction) with the output link of the control valve actuator, for example, with the rod of the control hydraulic cylinder (the control drive and its output link are not shown in the drawings).

The upper rod 16 of the locking and regulating element 10 is measuring and connected to the movable link of the displacement sensor (in the drawings, the displacement sensor and its movable link are not shown).

Shut-off valve operates as follows.

When the valve cross section is closed (if there is a contact between the locking chamfer 13 of the locking-regulating element 10 and the sealing chamfer 5 of the seat 4), the working fluid acts on the locking-regulating element 10 with the resulting force P _nip [see expression (4)] directed towards the saddle 4.

The specified force at any pressure value p in the valve outlet channel 3 from a range from zero to the pressure in the valve inlet channel 2 (supply pressure p _num ) even if the control valve actuator fails, creates a locking facet 13 of the locking-regulating element 10 on the contact surface the sealing facet 5 of the seat 4 of the voltage sufficient to ensure a tight separation of the input 2 and output 3 channels of the valve [see inequality (1)]. At the same time (due to the limited maximum value of the stresses caused by the force F _engraft) even when creating by the control actuator further efforts valve clamping locking and regulating member 10 to the seat 4, the amount of stress on the surface of locking chamfer contact 13 and the sealing lip 5 does not exceed the value of stresses admissible from the condition of the strength of the contacting surfaces.

When the locking and regulating element 10 relative to the seat 4 under the control of the valve actuator (the valve actuator is not shown in the drawings) is less than the overlap of the cylindrical sealing belts 14 and 6, respectively, of the locking and regulating element 10 and the seat 4, the pressure in the space between the locking the regulating element 10 and the saddle 4 in the area limited by the specified cylindrical sealing bands 14 and 6 and the entrance to the gap between the locking chamfer 13 of the locking and regulating element 10 and the sealing Chamfer 5 of seat 4 rises to a value equal to or close to the pressure _pit in the valve inlet channel (since the gap between the cylindrical sealing belts 14 and 6 has a large hydraulic resistance). In this case, the resulting force acting on the side of the working fluid on the shut-off-regulating element 10 decreases in value from the value of R _pzh , determined by the formula (4), to the value of P _close determined by the formula (8), but at any pressure p in the outlet channel 3 of the valve from a range from zero to the pressure in the inlet channel 2 of the valve (supply pressure p _pit ) remains directed towards the seat 4 (that is, towards the closing of the valve bore) and sufficient in size to overcome the corresponding forces the phenomena and movements of the locking-regulating in the direction of the saddle until it comes into contact with it [see inequality (2)].

Reducing the resulting force of hydrostatic pressure of the working fluid on the locking and regulating element 10 after tearing off the locking chamfer 13 of the locking and regulating element 10 from the sealing chamfer 5 of the seat 4 facilitates the subsequent displacement of the locking and regulating element 10 in the direction of opening the valve passage section and, all other things being equal, helps to reduce the time required to open the bore.

When the locking and regulating element 10 is moved relative to the seat 4 under the action of the control valve actuator (the valve is not shown in the drawings) by an amount equal to or greater than the overlap of the cylindrical sealing belts 14 and 6, respectively, of the locking and regulating element 10 and saddle 4, the passage section opens valve, which is the lateral surface of the truncated cone, formed by the normals to the lateral profiled surface 20 of the shank 15 of the locking and regulating element 10, made from ek edge of the cylindrical sealing rib 6 of the saddle 4, proximal to the sealing lip of the last 5 (see FIG. 2). Since the lateral surface 20 of the shank 15 is profiled on the basis of equation (3), then in the entire range of the change in the passage area of the proposed shut-off and control valve, a relative error in the flow control is provided that does not exceed a predetermined allowable value of 8.

Thanks to the specified profiling of the side surface 20 of the shank 15, the channel 21 formed by the indicated surface and the surface of the central passage 7 of the seat 4 is smoothly expanded towards the outlet channel 3, which reduces the likelihood of a tear-off cavitation valve during operation leading to the most intense cavitation wear of valve elements (see: Bocharov Yu.A., Denisyuk A.K. Improving the flow part of valve distributors for hydraulic forging and stamping Impact / forging and stamping machines full-time production -. 1974. - №5 -. S.31-33).

Since, by the beginning of the opening of the valve’s cross-section opening, the locking chamfer 13 of the locking-regulating element 10 is shifted relative to the sealing chamfer 5 of the seat 4 by a distance equal to the overlap of the cylindrical sealing belts 14 and 6, the area of the channel formed by the chamfers 13 and 5 after opening the the cross section of the valve significantly exceeds the area of the specified bore. Due to this, the chamfers 13 and 5 are deliberately located outside the zone of cavitation processes that are possible in the flow part of the valve during its operation and are not subject to cavitation wear, which contributes to an increase in their durability.

Under normal operating conditions of the valve, a change in the position of its locking and regulating element 10 occurs in strict accordance with a change in the position of the output link of the valve control actuator (the control actuator and its output link are not shown in the drawings) connected to the lower stem 17 of the locking and regulating element 10.

If the connection between the lower stem 17 and the output link of the valve control actuator is broken and the specified link is displaced in the direction of decreasing the passage area of the valve, the locking and regulating element 10 is subjected to the action of a force P _closed by it from the working fluid side [see expression (8), inequality (2)] is shifted in the direction of its saddle 4 until it stops against it or until the rod 17 stops against the output link of the control drive (depending on the position this link has moved to).

When braking the output link of the control drive (for example, due to the disappearance of the power supply of the drive), the locking-regulating element 10 under the action of the force P _closed on it by the working fluid [see expression (8), inequality (2)] is shifted in the direction of its saddle 4 to the stop in it, moving with it the output link of the control drive. As a result, the bore of the shut-off and control valve is closed, which helps to prevent emergency situations associated with a failure of the control drive.

Thus, the implementation of the invention provides increased reliability of hermetic closure of the bore of the shut-off and control valve in emergency situations (for example, if the rod of the shut-off-control element breaks with the output link of the valve control actuator) and high accuracy of controlling the flow rate of the working fluid using it over the entire range changes in the flow area of the valve.

The shut-off and control valve can be used in hydraulic actuators for forging and stamping presses.

Literary sources

1. Control valve: USSR author's certificate No. 1543170. MKI F16K 47/02. Stated March 31, 1987. Published 02/15/1990.

2. Shut-off and control valve: RF Patent No. 2103583. MKI F16K 39/02. Stated April 1, 1996. Published on January 27, 1998.

Claims (2)

1. Shut-off and control valve, comprising a housing with connecting inlet and outlet channels, in the bore of which a seat is made with a sealing chamfer and a central cylindrical sealing girdle having a diameter not larger than the inner diameter of the seat bevel, and a bore and a shut-off control element is placed with a coaxial guide cylindrical part, a collar with a locking chamfer, a reciprocal cylindrical sealing girdle and a shank, connected with two diametrically located rods, to the ends of which through the sealed holes extend in opposite directions beyond the valve body, while the valve body is hermetically sealed with a cover located in relation to the locking and regulating element from the side opposite the valve seat, and the locking and regulating element is installed to form an inlet the cavity connected to the connecting inlet channel of the valve, with the formation between the surfaces of the shank of the locking-regulating element and the Central passage bore of the channel seat, connected to the connecting outlet channel of the valve, and with the formation between the surfaces of the locking-regulating element and the cover of the valvular cavity in communication with the connecting output channel, characterized in that the diameter of the guide cylindrical part of the locking-regulatory element is smaller than the diameter of its cylindrical sealing girdle, and the diameter of the upper the rod of the locking and regulating element located on the side of the supravalvular cavity is made smaller than the diameter of the lower rod located with Rhone outlet valve, and said diameters throughout the possible range of values of pressure in the outlet channel of the valve system satisfy the following inequalities:

where D _n - the diameter of the guide cylindrical part of the locking and regulating element; d _kn , D _kv - respectively the outer and inner diameters of the contact surface of the locking chamfer of the locking-regulating element and the sealing chamfer of the saddle; D _sh.n , D _sh.v - diameters of the lower and upper rods of the locking and regulating element, respectively; D _pz - the diameter of the cylindrical sealing belt locking element; P _pit - constant pressure (supply pressure) in the valve inlet; p is the pressure in the outlet channel of the valve (0≤p≤p _pit ); σ _min , σ _max are the values of the minimum (from the condition of tightness) and maximum (from the condition of strength) allowable stresses on the contact surface of the locking facet of the locking element and the sealing facet of the saddle (σ _min > _pit ); R is the force that must be applied to the locking and regulating element in order to move it in the direction of the saddle until it contacts it from the position at which the valve cross-section is open. 2. The valve according to claim 1, characterized in that the lateral surface of the shank of the locking-regulating element is profiled based on the following equation establishing the relationship between the current required value of the diameter D _{z of the} shank and the coordinate z measured along the axis of the shank from the plane of its junction with the cylindrical sealing belt locking element

where D _nc is the diameter of the Central cylindrical sealing belt of the saddle; D _z - the current required value of the diameter of the shank; z is the coordinate measured along the axis of the shank from the plane of its junction with the cylindrical sealing belt of the locking and regulating element; And ₀ is the initial value of the cross-sectional area between the shank of the locking and regulating element and the Central cylindrical sealing belt of the saddle, equal to the area of the ring, the outer diameter of which is equal to the diameter of the sealing belt of the saddle, and the inner diameter of the cylindrical sealing belt of the locking and regulating element; σ is the allowable value of the relative error in the regulation of the flow rate of the working fluid; Δ is the maximum absolute value of the error in the installation of the locking and regulating element of the valve in the desired position.

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