CN105718696A - Deep sea Christmas tree electric-hydraulic control valve unit single electricity low pressure reversing valve designing method - Google Patents

Abstract

The invention provides a deep sea Christmas tree electric-hydraulic control valve unit single electricity low pressure reversing valve designing method.The method comprises the specific steps of determining the design scheme according to the actual using environment, verifying and calculating geometric dimensions, verifying and calculating valve body operation stress, conducting reexamination and verification and the like.The design method is reasonable and high in calculation efficiency and precision, design value is closer to actual use value, reliability of design work of a deep sea Christmas tree electric-hydraulic control valve unit double-electricity low pressure reversing valve is effectively improved, and thereby it is helpful to improve stability and reliability of a valve body in actual use process.

Description

A kind of deep-sea production tree electric hydraulic control valve group list electricity low pressure reversing valve designs method

Technical field

The present invention relates to a kind of single electricity low pressure reversing valve designs method, be exactly a kind of deep-sea production tree electric hydraulic control valve group list electricity low pressure reversing valve designs method.

Background technology

At present in the development process of deep-sea oil gas resource, deep-sea subsea production tree equipment application is very extensive, and in deep-sea oil gas development of resources, have vital effect, but find in actual use, the current single electricity low pressure reversal valve used on the production tree of deep-sea is often through empirical equation, the electricity low pressure reversal valve that traditional fresh water single electricity low pressure reversal valve or shallow sea water under water placed an order carries out transforming and designs preparation, although the needs of abyssal environment operation can be met to a certain extent, but design in this way and there is bigger error between the running technology parameter of the single electricity low pressure reversal valve of deep-sea production tree that preparation all obtains and practical service environment, thus causing single electricity low pressure reversal valve operation stability wretched insufficiency under abyssal environment, the experience that tradition is passed through simultaneously is in carrying out single electricity low pressure reversing valve designs process, computational accuracy wretched insufficiency on the one hand, on the other hand computational efficiency also relatively low under, also cannot effectively check checking to through calculated design structure simultaneously, thus also causing great puzzlement to design work, hence for this present situation, in the urgent need to developing a kind of highly versatile and simple valve design and preparation method, to meet actually used needs.

Summary of the invention

It is an object of the invention to provide the present invention and a kind of deep-sea production tree electric hydraulic control valve group list electricity low pressure reversing valve designs method is provided.

In order to achieve the above object, the present invention provides following technical scheme:

A kind of deep-sea production tree electric hydraulic control valve group list electricity low pressure reversing valve designs method, comprises the steps:

The first step, design is determined according to practical service environment, deep-sea according to valve body runs actual environment situation and working media situation under water, the basic frame for movement of the effective working environment subject range primarily determining that valve body, the every running technology index setting valve body and valve body；

Second step, physical dimension calculation and check, the valve body technical parameter set according to the first step and basic frame for movement, the physical dimension of valve body is carried out calculation and check, wherein needs oil inlet and outlet diameter, cue ball valve base endoporus and rod diameter, the minimum aperture of main valve valve port and main valve plug stroke are carried out calculation and check；

3rd step, valve body runs stress calculation and check, the running environment set according to the first step and technical parameter, concrete size in combination with second calculated frame for movement, it is calculated stressing conditions each in valve body ruuning situation checking, wherein needs frictional resistance, the resistance of motion, hydraulic card clamping force, stable state fluid power, spool active force and return spring elastic force are carried out calculation and check；

4th step, review is checked, the setup parameter scope according to the first step, selected least one set data, and is brought into by selected data in second step and the calculated concrete data of the 3rd step, carries out checking review then in conjunction with valve body practical operation situation and calculates.

Further, it is characterised in that: in described second step, to carry out calculation and check formula as follows for oil-out diameter, cue ball valve base endoporus and rod diameter, the minimum aperture of main valve valve port and main valve plug stroke:

Oil-out diameter computing formula:

Wherein: d hydraulic fluid port diameter

Q--metered flow (l/min)；

V oil inlet and outlet diameter d goes out oil flow, and the more big speed of pressure is more high；

Cue ball valve base diameter of bore and rod diameter and steel ball size computing formula:

d1≥1/2D1

By the flow formula of circular passage between valve port and push rod it is

$Q=\frac{\mathrm{\π}}{4}\[{D_1}^2-{d_1}^2\]V$

Above formula flow Q brings into metered flow, the oil flow V in circular passage, because ofThen

$Q\≤\frac{\mathrm{\π}}{4}\[{D_1}^2-{\left(\frac{D_1}{2}\right)}^2\]V$

Wherein: d1 rod diameter

D1 rod diameter cue ball valve base diameter of bore

Oil flow in v circular passage

The minimum aperture computing formula of main valve valve port:

According to by the flow rate calculation formula of valve port it is:

$Q=C_{d}A\sqrt{2\mathrm{\Δ}p/\mathrm{\ρ}}$

In formula:

Q passes through valve port fluid flow (m3/s)；

A valve port area of passage (m2)；

Δ p valve port two ends pressure reduction (Pa)；

Ρ fluid density (kg/m3)；

Cd is valve port flow coefficient；

Valve port area of passage A computing formula is:

$A={\mathrm{\πDhX}}_1(1+X_1/2h)/\sqrt{{(D/2)}^2+{(h+X_1)}^2};$

Wherein, $h=\sqrt{R^2-{\frac{D}{4}}^2};$

WhenX₁During < < R, $\sqrt{{(D/2)}^2+{(h+X_1)}^2}\&ap;R,\frac{X_1}{2h}\&ap;0,$ Above formula can be changed into

$A=\mathrm{\&pi;}D\sqrt{R^2-{\frac{D}{4}}^2}{X}_1/R;$

So the minimum aperture formula of the opening of valve can dissolve for:

$X_1=\frac{QR}{C_d\mathrm{\&pi;}D\sqrt{\frac{2\mathrm{\&Delta;}P(R^2-{\frac{D}{4}}^2)}{\mathrm{\&rho;}}}};$

Main valve plug climb displacement formula:

Be have to be larger than X1 by the stroke S of spool to obtain:

S>X1

Wherein: the stroke of S spool；

The minimum aperture of X1 main valve valve port；

Further, in the 3rd described step, the computing formula of frictional resistance, the resistance of motion, hydraulic card clamping force, stable state fluid power, spool active force and return spring elastic force is as follows:

Frictional resistance computing formula:

F_m=fN=0.275 π fP_bd_td₀

Wherein: F_mFrictional resistance；

F coefficient of friction, desirable f=0.1；

Dt diameter of piston rod；

D0 O end face diameter；

Pb allows back pressure；

Resistance of motion computing formula:

$F_V=\frac{\mathrm{\&pi;}DLV\mathrm{\&mu;}}{\mathrm{\&Delta;}r}$

Wherein: F_VThe resistance of motion；

D controls piston diameter；

L controls the contact length of piston and valve body hole；

V valve core movement speed；

μ fluid dynamic viscosity；

Between Δ r spool and valve body hole monolateral coordinates；

When hydraulic card clamping force calculates, when the generation of hydraulic card clamping force is because the flowing in fluid fit clearance between hydraulic valve spool and valve body, due to spool with valve body hole is tapered and offset, there is pressure distribution change in the different gap place making circumferencial direction, and spool is created a radial imbalance force, simultaneously because adopt O-ring seals to seal between the spool of the design and valve body, leakage rate is almost nil, and the design ignores hydraulic card clamping force；

Stable state fluid power computing formula:

F_w=C_dπDδΔpsinα(2-17)

Simultaneously, structure due to spool, when spool commutates two mouthfuls all in opening, liquid stream on one side is streamed under becoming, liquid stream on one side becomes upper streamed, but the steady-state fluid force that spool is subject to is all in one direction, all in opposite direction with liquid stream, so the steady-state fluid force of two ball valves need to be calculated in calculating formula.And no matter spool is in left position or right position, situation is all identical, when calculating, only with calculating spool at steady-state fluid force on one side, the steady-state fluid force of spool calculates the steady-state fluid force that need to calculate in two kinds of situations, and one is little opening, i.e. δ=1/3 δ max, when one is spool standard-sized sheet；

Thus obtaining, steady-state fluid force summation is:

ΣF_W=F_W1+F_W2=C_dπDδΔpsinα₁+C_dπD(S-δ)Δpsinα₂

In formula:

Cd is valve port flow coefficient；

D valve port diameter；

The opening amount of δ valve；

Δ p valve port two ends pressure reduction (Pa)；

α fluid flow angle

Spool Calculation of the force formula:

Due to valve body operationally, spool possesses unlatching and two kinds of duties of Guan Bi, it is therefore desirable to spool is calculated respectively at the active force opened and closure state is liked,

Therefore opening active force: F_{Open 1}> Σ F_m+F_p+F_t1

Closure state active force: F_{Open 2}> Σ F_w+F_p+F_t2

In formula: F_{Open 1}Opening spool active force；

F_{Open 2}Closure state spool active force；

ΣF_mFrictional resistance summation；

F_pThe pressure that spool produces；

F_t1Spring minimum workload.

ΣF_wSteady-state fluid force when spool circle is opened；

F_t2Little spring maximum working load；

Return spring elastic force computing formula:

K₁(X_T+ S)=Σ F_W1+ΣF_m1+F_P1

In formula:

ΣF_w1The spool steady-state fluid force when 569bar open；

ΣF_m1Spool is frictional resistance sum when 569bar；

F_P1The fluid pressure that ball valve core is subject to when 569bar.

Reasonable design method of the present invention, computational efficiency and precision are high, and design load and actually used value closer to, effectively raise the reliability of the design work of deep-sea subsea production tree electric hydraulic control valve group list electricity low pressure reversal valve, thus being favorably improved valve body stability in actual use and reliability.

Accompanying drawing explanation

In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, the accompanying drawing used required in embodiment or description of the prior art will be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the premise not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the inventive method flow chart.

Detailed description of the invention

Technical scheme is clearly and completely described by the accompanying drawing below in conjunction with the present invention, it is clear that described embodiment is only a part of embodiment of the present invention, rather than whole embodiments.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under not making creative work premise, broadly fall into the scope of protection of the invention.

Embodiment 1:

A kind of deep-sea production tree electric hydraulic control valve group list electricity low pressure reversing valve designs method as shown in Figure 1, comprises the steps:

The first step, design is determined according to practical service environment, deep-sea according to valve body runs actual environment situation and working media situation under water, the basic frame for movement of the effective working environment subject range primarily determining that valve body, the every running technology index setting valve body and valve body；

Second step, physical dimension calculation and check, the valve body technical parameter set according to the first step and basic frame for movement, the physical dimension of valve body is carried out calculation and check, wherein needs oil inlet and outlet diameter, cue ball valve base endoporus and rod diameter, the minimum aperture of main valve valve port and main valve plug stroke are carried out calculation and check；

Wherein:

Oil-out diameter computing formula:

Wherein: d hydraulic fluid port diameter

Q--metered flow (l/min)；

V oil inlet and outlet diameter d goes out oil flow, and the more big speed of pressure is more high, herein select 10m/s so:

$d\&GreaterEqual;\sqrt{\frac{4Q}{\mathrm{\&pi;}v}}=\sqrt{\frac{4\&times;21.7\&times;I{0}^{-5}}{\mathrm{\&pi;}\&times;10\&times;60}}\&times;1000=6.8mm$

Rounding takes d=6mm；

Cue ball valve base diameter of bore and rod diameter and steel ball size computing formula:

d1≥1/2D1

By the flow formula of circular passage between valve port and push rod it is

$Q=\frac{\mathrm{\&pi;}}{4}\&lsqb;{D_1}^2-{d_1}^2\&rsqb;V$

Above formula flow Q brings into metered flow, the oil flow V≤10m/s in circular passage, takesThen, because of $d_1\&GreaterEqual;\frac{1}{2}{D}_1,$ Then

$Q\&le;\frac{\mathrm{\&pi;}}{4}\&lsqb;{D_1}^2-{\left(\frac{D_1}{2}\right)}^2\&rsqb;V$

Wherein: d1 rod diameter

D1 rod diameter cue ball valve base diameter of bore

Oil flow in v circular passage

$D_1\&GreaterEqual;\sqrt{\frac{16Q}{3\mathrm{\&pi;}V}}=6.89mm$

D1=7mm, d1=3.5mm is taken after rounding,

Steel ball size 10mm；

The minimum aperture computing formula of main valve valve port:

According to by the flow rate calculation formula of valve port it is:

$Q=C_{d}A\sqrt{2\mathrm{\&Delta;}p/\mathrm{\&rho;}}$

In formula:

Q passes through valve port fluid flow (m3/s)；

A valve port area of passage (m2)；

Δ p valve port two ends pressure reduction (Pa)；

Ρ fluid density (kg/m3)；

Cd is valve port flow coefficient；

Valve port area of passage A computing formula is:

$A={\mathrm{\&pi;DhX}}_1(1+X_1/2h)/\sqrt{{(D/2)}^2+{(h+X_1)}^2};$

Wherein, $h=\sqrt{R^2-{\frac{D}{4}}^2};$

WhenX₁During < < R, $\sqrt{{(D/2)}^2+{(h+X_1)}^2}\&ap;R,\frac{X_1}{2h}\&ap;0,$

Above formula can be changed into

$A=\mathrm{\&pi;}D\sqrt{R^2-{\frac{D}{4}}^2}{X}_1/R;$

So the minimum aperture formula of the opening of valve can dissolve for:

$X_1=\frac{QR}{C_d\mathrm{\&pi;}D\sqrt{\frac{2\mathrm{\&Delta;}P(R^2-{\frac{D}{4}}^2)}{\mathrm{\&rho;}}}}$

Take Δ P=1MPa, Cd=1, so

X1=0.38mm；

Main valve plug climb displacement formula:

Be have to be larger than X1 by the stroke S of spool to obtain:

S>X1

Take S=2 (mm)

Wherein: the stroke of S spool；

The minimum aperture of X1 main valve valve port；

3rd step, valve body runs stress calculation and check, the running environment set according to the first step and technical parameter, concrete size in combination with second calculated frame for movement, it is calculated stressing conditions each in valve body ruuning situation checking, wherein needs frictional resistance, the resistance of motion, hydraulic card clamping force, stable state fluid power, spool active force and return spring elastic force are carried out calculation and check:

Frictional resistance computing formula:

F_m=fN=0.275 π fP_bd_td₀

Wherein: F_mFrictional resistance；

F coefficient of friction, desirable f=0.1；

Dt diameter of piston rod；

D0 O end face diameter；

Pb allows back pressure；

If main valve plug has 5 O-ring seals, for safety, calculate time during calculating according to the maximal friction of each O-ring seals and maximum back pressure, so respective frictional force is

Controlling the maximum back pressure of piston is Pb2=37.9bar, O diameter of section d02=1.8mm, piston diameter dt2

F_m2=0.0864P_b2d_t2d₀₂=4916d_t2

Fm3=4916 × 0.018=10.6N

Resistance of motion computing formula:

$F_V=\frac{\mathrm{\&pi;}DLV\mathrm{\&mu;}}{\mathrm{\&Delta;}r}$

Wherein: F_VThe resistance of motion；

D controls piston diameter；

L controls the contact length of piston and valve body hole, takes 6mm

V valve core movement speed, available spool movement time is that average speed during 0.01s replaces；So spool

$V=\frac{S}{\&lsqb;t_{dh}\&rsqb;}=\frac{0.002}{0.01}=0.2m/s;$

The kinematic viscosity of μ fluid dynamic viscosity HW443 is 1.9mm2/s；

Δ r spool and the monolateral fit clearance of valve body hole, take 0.05mm here.

So

$F_{V1}=\frac{{\mathrm{\&pi;d}}_{t1}\mathrm{LV\&mu;}}{\mathrm{\&Delta;r}}=0.14d_{t1}\left(N\right)---(2-16)$

By formula (2-17) it can be seen that owing to hydraulic oil viscosity is low, and the fit clearance of valve is relatively large, so the resistance of motion is very little, so being ignored in calculating formula.

When hydraulic card clamping force calculates, when the generation of hydraulic card clamping force is because the flowing in fluid fit clearance between hydraulic valve spool and valve body, due to spool with valve body hole is tapered and offset, there is pressure distribution change in the different gap place making circumferencial direction, and spool is created a radial imbalance force, simultaneously because adopt O-ring seals to seal between the spool of the design and valve body, leakage rate is almost nil, and the design ignores hydraulic card clamping force；

Stable state fluid power computing formula:

F_W=C_dπDδΔpsinα(2-17)

Simultaneously, structure due to spool, when spool commutates two mouthfuls all in opening, liquid stream on one side is streamed under becoming, liquid stream on one side becomes upper streamed, but the steady-state fluid force that spool is subject to is all in one direction, all in opposite direction with liquid stream, so the steady-state fluid force of two ball valves need to be calculated in calculating formula.And no matter spool is in left position or right position, situation is all identical, when calculating, only with calculating spool at steady-state fluid force on one side, the steady-state fluid force of spool calculates the steady-state fluid force that need to calculate in two kinds of situations, and one is little opening, i.e. δ=1/3 δ max, when one is spool standard-sized sheet；

Thus obtaining, steady-state fluid force summation is:

ΣF_W=F_W1+F_W2=C_dπDδΔpsinα₁+C_dπDCS-δ)Δpsinα₂

In formula:

Cd is valve port flow coefficient, takes Cd=1；

D valve port diameter；

The opening amount of δ valve；

Δ p valve port two ends pressure reduction (Pa), takes 1MPa during little opening, take 0.1MPa during big opening；

Take α=69 ° during the big opening of α fluid flow angle, during little opening, take α=21 °；

Structure due to spool, when spool commutates two mouthfuls all in opening, liquid stream on one side is streamed under becoming, liquid stream on one side becomes upper streamed, but the steady-state fluid force that spool is subject to is all in one direction, all in opposite direction with liquid stream, so the steady-state fluid force of two ball valves need to be calculated in calculating formula.And no matter spool is in left position or right position, situation is all identical, when calculating, only with calculate spool steady-state fluid force.

The steady-state fluid force of spool calculates the steady-state fluid force that need to calculate in two kinds of situations, and one is little opening, i.e. δ=1/3 δ max, when one is spool standard-sized sheet.

When spool is in little opening, δ=0.127mm, steady-state fluid force summation now is:

ΣF_W=F_W1+F_W2=C_dπDδΔpsinα₁+C_dπD(S-δ)Δpsinα₂(2-18)

ΣF_W=4.8N

When valve is in standard-sized sheet, δ=S=2mm, steady-state fluid force summation now is

ΣF_W=C_dπDδΔpsinα₁=4.1N；

Spool Calculation of the force formula:

Due to valve body operationally, spool possesses unlatching and two kinds of duties of Guan Bi, it is therefore desirable to spool is calculated respectively at the active force opened and closure state is liked,

Therefore opening active force: F_{Open 1}> Σ F_m+F_p+F_t1

Closure state active force: F_{Open 2}> Σ F_w+F_p+F_t2

In formula: F_{Open 1}Opening spool active force；

F_{Open 2}Closure state spool active force；

ΣF_mFrictional resistance summation；

F_PThe pressure that spool produces；

F_t1Spring minimum workload.

ΣF_wSteady-state fluid force when spool circle is opened；

F_t2Little spring maximum working load；

Return spring elastic force computing formula:

K₁(X_T+ S)=Σ F_W1+ΣF_m1+F_P1

In formula:

ΣF_w1The spool steady-state fluid force when 569bar open；

ΣF_m1Spool is frictional resistance sum when 569bar；

F_P1The fluid pressure that ball valve core is subject to when 569bar；

4th step, review is checked, the setup parameter scope according to the first step, selected least one set data, and is brought into by selected data in second step and the calculated concrete data of the 3rd step, carries out checking review then in conjunction with valve body practical operation situation and calculates.

Reasonable design method of the present invention, computational efficiency and precision are high, and design load and actually used value closer to, effectively raise the reliability of the design work of deep-sea subsea production tree electric hydraulic control valve group list electricity low pressure reversal valve, thus being favorably improved valve body stability in actual use and reliability.

The above; being only the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, any those familiar with the art is in the technical scope that the invention discloses; change can be readily occurred in or replace, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should described be as the criterion with scope of the claims.

Claims (3)

1. a deep-sea production tree electric hydraulic control valve group list electricity low pressure reversing valve designs method, it is characterised in that: described deep-sea production tree electric hydraulic control valve group list electricity low pressure reversing valve designs method comprises the steps:

The first step, design is determined according to practical service environment, deep-sea according to valve body runs actual environment situation and working media situation under water, the basic frame for movement of the effective working environment subject range primarily determining that valve body, the every running technology index setting valve body and valve body；

Second step, physical dimension calculation and check, the valve body technical parameter set according to the first step and basic frame for movement, the physical dimension of valve body is carried out calculation and check, wherein needs oil inlet and outlet diameter, cue ball valve base endoporus and rod diameter, the minimum aperture of main valve valve port and main valve plug stroke are carried out calculation and check；

3rd step, valve body runs stress calculation and check, the running environment set according to the first step and technical parameter, concrete size in combination with second calculated frame for movement, it is calculated stressing conditions each in valve body ruuning situation checking, wherein needs frictional resistance, the resistance of motion, hydraulic card clamping force, stable state fluid power, spool active force and return spring elastic force are carried out calculation and check；

4th step, review is checked, the setup parameter scope according to the first step, selected least one set data, and is brought into by selected data in second step and the calculated concrete data of the 3rd step, carries out checking review then in conjunction with valve body practical operation situation and calculates.

2. a kind of deep-sea according to claim 1 production tree electric hydraulic control valve group list electricity low pressure reversing valve designs method, it is characterised in that: in described second step, to carry out calculation and check formula as follows for oil-out diameter, cue ball valve base endoporus and rod diameter, the minimum aperture of main valve valve port and main valve plug stroke:

Oil-out diameter computing formula:

Wherein: d hydraulic fluid port diameter

Q--metered flow (l/min)；

V oil inlet and outlet diameter d goes out oil flow, and the more big speed of pressure is more high；

Cue ball valve base diameter of bore and rod diameter and steel ball size computing formula:

d1≥1/2D1

By the flow formula of circular passage between valve port and push rod it is

Above formula flow Q brings into metered flow, the oil flow V in circular passage, because ofThen

Wherein: d1 rod diameter

D1 rod diameter cue ball valve base diameter of bore

Oil flow in v circular passage

The minimum aperture computing formula of main valve valve port:

According to by the flow rate calculation formula of valve port it is:

In formula:

Q passes through valve port fluid flow (m3/s)；

A valve port area of passage (m2)；

Δ p valve port two ends pressure reduction (Pa)；

P fluid density (kg/m3)；

Cd is valve port flow coefficient；

Valve port area of passage A computing formula is:

Wherein,

WhenTime,

Above formula can be changed into

So the minimum aperture formula of the opening of valve can dissolve for:

Main valve plug climb displacement formula:

Be have to be larger than X1 by the stroke S of spool to obtain:

S>X1

Wherein: the stroke of S spool；

The minimum aperture of X1 main valve valve port.

3. a kind of deep-sea according to claim 1 production tree electric hydraulic control valve group list electricity low pressure reversing valve designs method, it is characterised in that: in the 3rd described step, the computing formula of frictional resistance, the resistance of motion, hydraulic card clamping force, stable state fluid power, spool active force and return spring elastic force is as follows:

Frictional resistance computing formula:

F_m=fN=0.275 π fP_bd_td₀

Wherein: F_mFrictional resistance；

F coefficient of friction, desirable f=0.1；

Dt diameter of piston rod；

D0 O end face diameter；

Pb allows back pressure；

Resistance of motion computing formula:

Wherein: F_VThe resistance of motion；

D controls piston diameter；

L controls the contact length of piston and valve body hole；

V valve core movement speed；

μ fluid dynamic viscosity；

Between Δ r spool and valve body hole monolateral coordinates；

When hydraulic card clamping force calculates, when the generation of hydraulic card clamping force is because the flowing in fluid fit clearance between hydraulic valve spool and valve body, due to spool with valve body hole is tapered and offset, there is pressure distribution change in the different gap place making circumferencial direction, and spool is created a radial imbalance force, simultaneously because adopt O-ring seals to seal between the spool of the design and valve body, leakage rate is almost nil, and the design ignores hydraulic card clamping force；

Stable state fluid power computing formula:

F_W=C_dπDδΔpsinα(2-17)

Simultaneously, structure due to spool, when spool commutates two mouthfuls all in opening, liquid stream on one side is streamed under becoming, liquid stream on one side becomes upper streamed, but the steady-state fluid force that spool is subject to is all in one direction, all in opposite direction with liquid stream, so the steady-state fluid force of two ball valves need to be calculated in calculating formula.And no matter spool is in left position or right position, situation is all identical, when calculating, only with calculating spool at steady-state fluid force on one side, the steady-state fluid force of spool calculates the steady-state fluid force that need to calculate in two kinds of situations, and one is little opening, i.e. δ=1/3 δ max, when one is spool standard-sized sheet；

Thus obtaining, steady-state fluid force summation is:

ΣF_W=F_W1+F_W2=C_dπDδΔpsinα₁+C_dπD(S-δ)Δpsinα₂

In formula:

Cd is valve port flow coefficient；

D valve port diameter；

The opening amount of δ valve；

Δ p valve port two ends pressure reduction (Pa)；

α fluid flow angle

Spool Calculation of the force formula:

Due to valve body operationally, spool possesses unlatching and two kinds of duties of Guan Bi, it is therefore desirable to spool is calculated respectively at the active force opened and closure state is liked,

Therefore opening active force: F_{Open 1}> Σ F_m+F_P+F_t1

Closure state active force: F_{Open 2}> Σ F_w+F_P+F_t2

In formula: F_{Open 1}Opening spool active force；

F_{Open 2}Closure state spool active force；

ΣF_mFrictional resistance summation；

F_PThe pressure that spool produces；

F_t1Spring minimum workload.

ΣF_wSteady-state fluid force when spool circle is opened；

F_t2Little spring maximum working load；

Return spring elastic force computing formula:

K₁(X_T+ S)=Σ F_W1+ΣF_m1+F_P1

In formula:

ΣF_w1The spool steady-state fluid force when 569bar open；

ΣF_m1Spool is frictional resistance sum when 569bar；

F_P1The fluid pressure that ball valve core is subject to when 569bar.