RU2018910C1 - Gas pressure regulator - Google Patents

Abstract

FIELD: automatic control. SUBSTANCE: gas pressure regulator has housing 1 with inlet cavity 2 and outlet cavity 3, first valve 4 interposed between them, first sensitive element, e.g. stepped piston 6 acting upon first valve 4 and in an initial position contacting with movable bushing 12 in which piston 10 with second valve 17 are disposed, third valve 12 and check valve 21 situated within the bushing, second check valve 26 for communicating cavity 7 between the steps of the stepped piston with outlet cavity 3. EFFECT: reduced output pressure deviations in time and in magnitude with increased extraction of gas from regulator. 3 cl, 1 dwg

Description

 The invention relates to automatic regulation and can be used in pneumatic systems for various purposes.

 A gas pressure regulator is known, comprising a housing with a first valve located between the inlet and outlet cavities, a first sensing element in the form of a step piston installed in the housing, the lower stage of which is connected to the first valve and forms the first cavity with the larger stage and housing, which is communicated through the throttle with atmosphere, a second sensing element in the form of a piston loaded with a task spring, and a second cavity, which is in communication with the outlet cavity and through the second valve with the first cavity, while n is placed in a sleeve installed in the housing between the piston and the larger stage of the staged piston and provided with a seat for the second valve, which is located in the piston, the second cavity is formed by the piston and the sleeve in which the seat of the third valve is placed in the sleeve, which forms with the larger stage of the staged the piston the third cavity, the second and third cavities are communicated through the third valve, and in the initial position, the sleeve is in contact with the piston and the larger step of the stepped piston, the third valve is squeezed from its seat the piston, and the connection of the third valve with its seat in the position of their contact is made with guaranteed leakage [1].

 With a stepwise increase in gas flow through the regulator, especially when switching from a wasteless mode, when the pressure in the first cavity is almost equal to the outlet pressure, the outlet pressure can decrease significantly to the full flow mode. The magnitude of the decrease in the outlet pressure and the time of its recovery depend on the nature of the emptying of the first and third cavities. In this regulator there are no technical solutions that limit the decrease in output pressure with increasing gas flow.

 Known gas pressure regulator having the same essential features as the above analogue. In addition, in it behind the third valve, a throttle and a check valve are installed in parallel, facing the outlet to the third cavity [2].

 In this regulator, when the flow is switched on stepwise, the output pressure drops sharply, the piston moves the third valve, but the outflow of the medium through the third valve and the rate of pressure drop in the third cavity are limited by the throttle.

 This solution contributes to a positive technical result, but in some cases is not enough.

 A technical solution is proposed in which the deviation of the outlet pressure decreases in magnitude and time with an increase in gas extraction from the regulator.

 The essence of the invention is that the combination of the above essential features inherent in analogue and prototype, supplemented by a group of new essential features.

> 1, , где f₁ и f₃ - сечения дросселей, установленных соответственно между первой полостью и атмосферой и между третьей и второй полостями;
P₁ и Р₃ - давления соответственно перед сечениями f₁ и f₃;
F₁ и F₃ - эффективные площади ступенчатого поршня, на которые действуют давления соответственно в первой и третьей полостях;
K₁=

, где R - газовая постоянная;
Т₁₀ и V₁₀ - начальные температуры газа в первой полости и ее объем;
K₃=

, где Т₃₀ и V₃₀ - начальные температура газа в третьей полости и ее объем;
А₁ и А₃₀ - коэффициенты, учитывающие параметры газовой среды и сечений f₁ и f₃ и определяющие расходы через эти сечения.A second non-return valve is installed, the inlet of which is in communication with the first cavity, and the outlet - with the outlet cavity, and there is a ratio of parameters corresponding to the state of the controller after a stepwise increase in gas flow

> 1,, where f ₁ and f ₃ are the sections of the chokes installed respectively between the first cavity and the atmosphere and between the third and second cavities;
P ₁ and P ₃ - pressure, respectively, before the sections f ₁ and f ₃ ;
F ₁ and F ₃ - the effective area of the stepped piston, which are affected by pressure, respectively, in the first and third cavities;
K ₁ =

where R is the gas constant;
T ₁₀ and V ₁₀ - the initial gas temperature in the first cavity and its volume;
K ₃ =

where T ₃₀ and V ₃₀ are the initial gas temperature in the third cavity and its volume;
And ₁ and A ₃₀ are coefficients that take into account the parameters of the gas medium and sections f ₁ and f ₃ and determine the costs through these sections.

, , где Р_н - давление в выходной и третьей полостях (давление настройки) до увеличения расхода газа через регулятор;
V_з.н. - объем третьей полости до увеличения расхода газа через регулятор, и
P₁₀= P₃₀-

, где Т_к - усилие на первом клапане, воспринимаемое ступенчатым поршнем.In addition, there are formulas that determine the initial pressure P ₃₀ in the third cavity and P ₁₀ in the first cavity after increasing the gas through the regulator:
P ₃₀ = P

,, where R _n - pressure in the outlet and third cavities (setting pressure) until the gas flow through the regulator increases;
V _ZN - the volume of the third cavity to increase the gas flow through the regulator, and
P ₁₀ = P ₃₀ -

where T _to - the force on the first valve, perceived by the stepped piston.

 Moreover, in front of the throttle, which communicates the first cavity with the atmosphere, a pressure regulator is installed.

 The significance of the distinguishing features of the invention is apparent from the following.

 Since a stepwise increase in gas flow rate requires a decrease in pressure in the first cavity to squeeze the first valve, and gas flow into the atmosphere through the throttle at the outlet of the cavity is limited, the second non-return valve, responding to a sharp decrease in pressure in the outlet cavity, relieves a significant amount gas to equalize the pressure in it with the pressure in the outlet cavity.

 After this preliminary emptying of the first cavity, it becomes acceptable to reduce the pressure in it due to moderate leaks through the throttle. Since after reducing the outlet pressure, it is emptied through the throttle into the outlet cavity and the third cavity, it is necessary to have a clear condition guaranteeing a relatively quick restoration of the outlet pressure, taking into account the initial and changed volumes of the cavities, the pressures in them, the flow rates through the throttling sections, etc. This condition is expressed in the claims by the ratio of the parameters.

и P₁₀= P₃₀-

позволяют найти параметры Р₁₀ и Р₃₀ как начальные значения имеющихся в соотношении параметров Р₁ и Р₃.Formulas P ₃₀ = P

and P ₁₀ = P ₃₀ -

allow you to find the parameters P ₁₀ and P ₃₀ as the initial values available in the ratio of the parameters P ₁ and P ₃ .

 The installation of a pressure regulator in front of the throttle facilitates the task of limiting the unproductive flow rate from the third cavity and determining this flow rate to ensure the ratio in the formula.

 The derivation of the formulas and relations is as follows.

At the conclusion, suppose the maximum stepwise increase in gas flow from G = 0 to G = G _max . After increasing the flow rate, the output pressure from the tuning value of P _n decreases stepwise to a value of P _out . ₀ . Taking into account the operation of the second check valve, the pressure P _out.0 is also set in the first cavity, i.e. at the initial moment after an increase in gas flow, the pressure P ₁₀ in the first cavity is equal to P _out . ₀ .

You can write the equation of static forces
P _{30 ˙} F ₃ - Pv _out.0 (F ₁ + F _out. ) - T _k = 0, (1) where P ₃₀ is the pressure in the third cavity at the initial moment after its expansion due to the movement of the step piston;
F ₃ is the effective area of the stepped piston, perceiving pressure in the third cavity;
F ₁ is the effective area of the stepped piston, perceiving pressure in the first cavity;
F _o - the effective area of the stepped piston, perceiving the output pressure;
T _to - the force on the first valve after an increase in flow rate, perceived by a stepped piston.

.. (2)
Так как F_вых + F₁ = F_з, то с учетом выражения (1) P₃₀˙ F_з-P_вых.0˙F_з = T_к или P_вых.о= P₃₀-

..Having accepted the process when expanding the third cavity polytropic and the pressure in it until the expansion is equal to P _n (force T _{to the} valve completely closed on the saddle), write
P _n V _zn ⁿ = P ₃₀ V ₃₀ ⁿ , where V _zn ⁿ and V ₃₀ ⁿ are the volume of the third cavity, respectively, before and after its expansion;
n is the polytropic index, or P ₃₀ = P

.. (2)
Since F _O + F ₁ = F _s, then with the expression (1) P ₃₀ -P _z ˙ F _vyh.0 ˙F _s = T or P _{to vyh.o} = P ₃₀ -

..

(3)
Найденные по формулам (2) и (3) параметры входят как частные (начальные) значения в выводимое ниже соотношение и необходимы для расчета опорожнения первой и третьей полостей.Taking into account P out. ₀ = P ₁₀ P ₁₀ = P ₃₀ -

(3)
The parameters found by formulas (2) and (3) enter as particular (initial) values in the relation below and are necessary for calculating the emptying of the first and third cavities.

When the gas is withdrawn from the regulator in _stages , the output pressure decreases to P out. ₀ , the second valve closes, the gas flow into the first cavity through it stops, and along with the gas outflow into the atmosphere, there will be gas outflow from the third cavity through the throttle in the second non-return valve.

The release value of the first valve and the pressure P _{out.0 remain} for some time, if equality is maintained
P ₃ ¹ F ₃ = P ₁ ¹ F ₁ , (4) where P ₃ ¹ and P ₁ ¹ are the rates of pressure drop in the third and first cavities.

If there is no equality (4), then when P ₃ ^' F ₃ > P ₁ ^' F _{1 the} pressure in the outlet cavity P _o decreases to a certain minimum value. When P ₃ ^' F ₃ <P ₁ ^' F ₁ (5), the pressure P _o increases to the setting pressure P _n , which corresponds to a smaller deviation of the output pressure.

или ΔP = ΔG

,, где P_a, G_a и P_б,G_б - начальные и конечные значения давлений и веса газа в полостях.Based on the law PV = GRT, the pressure drop in the cavities in the general case can be written
P _a - P _b = (G _a -G _b )

or ΔP = ΔG

, where P _a , G _a and P _b , G _b are the initial and final values of the pressure and weight of the gas in the cavities.

. Приняв

= K_i записывают для третьей и первой полостей Р

= Δ G₃ $\genfrac{}{}{0ex}{}{\text{'}}{\text{0}}$ ^˙ K₃₀ (6) и P $\genfrac{}{}{0ex}{}{\text{'}}{\text{1}}$ ₀ = ΔG $\genfrac{}{}{0ex}{}{\text{'}}{\text{1}}$ ₀ K₁₀. (7)
Обозначив Δ G^' = g, записывают
g = A ˙f ˙P (см. , например, Дмитриев В.Н., Гроздецкий В.Г. Основы пневмоавтоматики. М.: Машиностроение,1973, с.30) где f - дросселирующее сечение;
Р - давление на входе дросселя;
А - коэффициент, учитывающий параметры газовой среды и расходный коэффициент дросселирующего сечения.Secondary changes can be recorded
ΔP ′ = P ′ = ΔG ′

. Having accepted

= K _i write for the third and first cavities P

= Δ G ₃ $\genfrac{}{}{0ex}{}{\text{''}}{\text{0}}$ ^˙ K ₃₀ (6) and P $\genfrac{}{}{0ex}{}{\text{''}}{\text{1}}$ ₀ = ΔG $\genfrac{}{}{0ex}{}{\text{''}}{\text{1}}$ ₀ K ₁₀ . (7)
Denoting Δ G ^' = g, write
g = A ˙f ˙P (see, for example, Dmitriev VN, Grozdetsky VG Fundamentals of pneumatic automation. M: Mechanical engineering, 1973, p.30) where f is the throttling section;
P is the pressure at the inlet of the throttle;
A - coefficient taking into account the parameters of the gas medium and the flow coefficient of the throttling section.

> 1 . (8)
Параметры в последнем выражении соответствуют началу процесса после ступенчатого увеличения расхода газа через регулятор и обуславливают начало возрастания давления от значения Р_вых.0.Then g ₁₀ = f _1˙ P ₁₀ ˙ A ₁₀ and g ₃₀ = f ₃ ˙ P ₃₀ ˙ A ₃₀ , and equalities (6) and (7) have the form P ₃₀ ^' = A ₃₀ ˙ f ₃ ˙ P ₃₀ ˙ K ₃₀ and P ₁₀ ^'= A ₁₀ ˙f ˙P ₁ x _{10 10 Xk.}
Substituting the last expression into expression (5), we obtain
f _{3 ˙} P _{30 ˙} F ₃₀ ˙K ₃₀ ˙A ₃₀ <f _1˙ P ₁₀ ˙F ₁₀ ˙K ₁₀ ˙A ₁₀ or

> 1. (8)
The parameters in the last expression correspond to the beginning of the process after a stepwise increase in gas flow through the regulator and determine the beginning of the increase in pressure from the value of P out ₀ .

The gas flow from the third cavity due to the pressure drop in front of the cross section f ₃ , the rate of pressure drop in it and therefore the value of the entire denominator of the ratio can only decrease.

Ensuring the appropriate value of the numerator, which has initial parameters in relation (8), in most cases, under conditions of pressure drop in the first cavity, is most easily solved by stabilizing the pressure before the cross section f ₁ . In this case, to ensure the ratio (5), a predetermined flow rate through the cross section f _{1 is} also stabilized. This is achieved by installing a low-pressure pressure regulator before the cross section.

> 1 ..Thus, relation (8), which provides a technical result at the initial values of the parameters, turns out to be valid for their current values,
those.

> 1 ..

In this case, some changes in the temperature of the gas in the cavities during the emptying process and a change in their volumes due to small movements of the first valve in the calculation can be neglected and K ₁ = K ₁₀ and K ₃ = K ₃₀ .

 The gas pressure regulator is shown schematically in the drawing.

 The controller comprises a housing 1 with a first valve 4 and a seat 5 located between the inlet 2 and the outlet 3 cavities, a first sensing element made by a stepped piston 6, connected with the first valve 4 with its lower stage and forming the first cavity 7, connected with the larger stage and the housing 1 through the pressure regulator 8 and the throttle 9 with the atmosphere. There is a second sensing element - a piston 10, loaded with a task spring 11 and forming a second cavity 13 with a sleeve 12, communicated by a channel 14 with an output cavity 3. A saddle 16 is installed on the sleeve 12, which forms a third cavity 15 with a housing 1 and a larger stage piston 6, a saddle 16 for the second valve 17, through which the second cavity 13 can communicate through the channel 18 with the first cavity 7. In the sleeve 12, a third valve 19 with a seat 20 and a first check valve 21 with a seat 22 are installed, through which the second cavity through the channel 23 with the throttle 24 13 may be reported the third cavity 15. The rod 25 connects a lower level of the stepped piston 6 with a first valve 4. The second check valve 26 provides for channels 27 and 28 of the overpressure of the first cavity 7 through the second cavity 13 into outlet cavity 3.

 The third valve 19 when landing on the saddle 20 provides leakage isolation of the third 15 cavity with the second 13 cavity. The adapter 29 with the sealing rings allows movement of the stepped piston 6 relative to the sleeve 12.

Step piston 6 is subject to pressure in the outlet, first 7 and third 15 cavities. In accordance with this, with respect to the shown design variant, there are effective areas: F ₁ - the difference of the areas of the larger and smaller steps minus the area of the adapter 29, F ₃ - the area of the larger step minus the area of the adapter 29, F _o - the area of the smaller step.

 The regulator operates as follows.

 In the initial position, the sleeve 12 is pressed by the task spring 11 through the piston 10 to the housing 1. The first valve 4 is pressed by the rod 25 and the step piston 6 is pressed from the seat 5. The second valve 17 and the seat 16 divide the second 13 and the first 7 cavity. The third valve 19, in contact with the piston 10, is pressed away from the seat 20, and the first 21 and second 26 check valves are in contact with their seats. The pressure regulator 8 is configured to output pressure, which is lower than the minimum possible pressure in the first cavity 7, which ensures stabilization of flow through the throttle 9.

 When supplying the inlet pressure to the inlet cavity 2, the gas through the seat 5 fills the outlet cavity 3, through the channel 14 - the second cavity 13 and through the seats 20 and 22 and the throttle 24 - the third cavity 15.

Upon reaching a certain pressure in the outlet 3 and the third 15 cavities, the sleeve 12 is moved all the way into the housing 1, compressing the spring 11 of the job. When the saddle 16 is closed, the stepped piston 6 acts on the first valve 4 with a force that makes up the difference in effort from gas pressure over the areas F _o and F ₃ .

When the pressure in the outlet 3 and second 13 cavities reaches the pressure setting P _n , the piston 10 with the second valve 17 moves and gas enters through the channel 18 into the first cavity 7. By increasing the pressure in the first cavity 7 to the area F _{1, the} step piston 6 is brought into position corresponding to the required amount of squeezing of the first valve 4 from the seat 5 and the flow of gas into the outlet cavity 3.

 In steady-state control processes, the pressure in the outlet cavity 3 is maintained automatically due to the reaction of the piston 10 to the outlet pressure and a change in the gas flow through the seat 16 to the first cavity 7, while the outflow of the medium from the first cavity 7 is carried out through the regulator 8 and the throttle 9.

 Filling the third cavity when the regulator enters the control mode with sufficient speed is carried out through the pressed third valve 19 and the first check valve 21 with a throttle 24. In steady-state conditions, the complete disconnection of the third cavity 15 with the second cavity 13 is eliminated due to the guaranteed leakage of the third valve 19 on the seat 20, which is necessary, for example, during thermal expansion - compression of the gas in the third cavity 15 or its overfilling in transients.

With a stepwise increase in gas flow through the regulator, for example, when switching from a wasteless mode to a maximum flow rate, the output pressure also decreases stepwise. To quickly exit the regulator to a steady state control mode with an outlet pressure P _n with smaller deviations of the outlet pressure in the transition process, a lower pressure decrease in the third cavity 16 is required, which decreases due to the expansion of this cavity when the seat 5 is opened and the gas outflow through the throttle 24 into the second cavity 13, the pressure in which is even lower. In addition, it is also necessary to quickly reduce the pressure in the first cavity 7 as a solution to counteract the opening of the seat 5. In this case, a quick and significant pressure relief from the first cavity 7 is carried out through the second check valve 26. To enter the control mode with pressure P _n, it is necessary that the speed of decreasing the force on the stepped piston 6 from the pressure in the first cavity 7 was greater than the speed of decreasing the force from the pressure in the third cavity 15.

> 1 ..The last condition corresponds to the ratio of parameters

> 1 ..

So, the technical result of the invention is a decrease in the magnitude and time of the deviation of the outlet pressure with increasing gas withdrawal from the regulator relative to the result available in the prototype, achieved by first depressurizing the first cavity through the second check valve and further streamlining the defrosting of the first and third cavities of the regulator in accordance with the proposed ratio of parameters. To determine some of them (P ₁ and P ₃ ) derived formulas. Moreover, the greater the unit value of the ratio of parameters, the more the time to reach the required pressure is reduced.

Claims (3)

1. GAS PRESSURE REGULATOR, comprising a housing with a first valve located between the inlet and outlet cavities, a first sensing element in the form of a step piston installed in the housing, the lower stage of which is connected to the first valve and forms the first cavity, which is communicated through the throttle, with the larger stage and housing with the atmosphere, a second sensing element in the form of a piston loaded with a task spring, and a second cavity, which is in communication with the outlet cavity and through the second valve, with the first cavity, the piston being it is mounted in a sleeve installed in the housing between the piston and the larger stage of the staged piston and provided with a seat for the second valve, which is located in the piston, the second cavity is formed by the piston and the sleeve, in which the seat of the third valve is located in the sleeve, which forms with the larger stage of the staged piston the third cavity, while the second and third cavities are communicated through the third valve and a throttle and a first check valve installed behind it in parallel with the outlet to the third cavity, and the sleeve in the initial position to It is in contact with the piston and the larger step of the stepped piston, the third valve is squeezed from its seat by the piston and the connection of the third valve with its seat in their contact position is made with guaranteed leakage, characterized in that there is a second non-return valve, the input of which is connected to the first and the output to output cavities and there is a ratio of parameters corresponding to the state of the regulators after a stepwise increase in gas flow

> 1 ,,
where f ₁ , f ₃ - cross section of the chokes installed respectively between the first cavity and the atmosphere and between the third and second cavities;
P ₁ , P ₃ - pressure, respectively, before the sections f ₁ , f ₃ ;
F ₁ , F ₃ - effective area of the stepped piston, which are affected by pressure, respectively, in the first and third cavities;
K ₁ =

,
where R is the gas constant;
T ₁₀ , V ₁₀ - initial gas temperature in the first cavity and its volume;
K ₃ =

,
where T ₃₀ , V ₃₀ - the initial temperature of the gas in the first cavity and its volume;
A ₁ , A ₃ - coefficients that take into account the parameters of the gas medium and sections f ₁ , f ₃ that determine the costs through these sections. 2. The controller according to claim 1, characterized in that the ratio
P ₃₀ = P

,,
P ₁₀ = P ₃₀ -

,,
where P ₃₀ and P ₁₀ are, respectively, the initial pressure in the third and first cavities after increasing the gas flow through the regulator;
P _n - pressure in the outlet and third cavities to increase flow through the regulator;
V _zn - the volume of the third cavity to increase the flow rate through the regulator;
T _to - the force on the first valve after increasing the gas flow through the regulator, perceived by the step piston.  3. The regulator according to claims 1 and 2, characterized in that a pressure regulator is installed in front of the throttle communicating the first cavity with the atmosphere.