阅读说明：本技术 自力式斜角阀 (Self-operated oblique angle valve ) 是由 柴为民 陈永新 路远航 张雪根 于 2019-06-27 设计创作，主要内容包括：本发明公开了一种自力式斜角阀,包括调节阀和定差减压阀,调节阀设置在上阀体腔体内,定差减压阀设置在下阀体腔体内,定差减压阀设置在调节阀之后；上、下阀体由紧固件连结成一体,其中心线在同一轴线上,且与进出水孔的水平轴线有一定的斜角,调节阀包括手轮、导向套、阀杆和阀瓣；定差减压阀包括滑阀、弹簧、膜片、下阀盖、调节螺杆、调节垫片、压板和压紧螺母。当介质流通时,如果进水腔或出水腔的压力发生波动,由于定差减压阀对调节阀出口端的压力进行补偿,因此能保证调节阀两端的压差不变,从而保证通过的流量不变。(The invention discloses a self-operated bevel valve, which comprises an adjusting valve and a constant-differential pressure reducing valve, wherein the adjusting valve is arranged in an upper valve body cavity, the constant-differential pressure reducing valve is arranged in a lower valve body cavity, and the constant-differential pressure reducing valve is arranged behind the adjusting valve; the upper and lower valve bodies are connected into a whole by a fastener, the central lines of the upper and lower valve bodies are on the same axis, and a certain oblique angle is formed between the central lines and the horizontal axis of the water inlet and outlet holes, and the regulating valve comprises a hand wheel, a guide sleeve, a valve rod and a valve clack; the fixed-differential pressure reducing valve comprises a slide valve, a spring, a diaphragm, a lower valve cover, an adjusting screw rod, an adjusting gasket, a pressing plate and a pressing nut. When the medium circulates, if the pressure in the water inlet cavity or the water outlet cavity fluctuates, the pressure at the outlet end of the regulating valve is compensated by the constant-pressure-difference pressure-reducing valve, so that the pressure difference at the two ends of the regulating valve can be ensured to be constant, and the flow passing through the regulating valve is ensured to be constant.)

1. The utility model provides a formula of relying on oneself valve that inclines, includes governing valve and fixed differential pressure relief valve, its characterized in that: the regulating valve is arranged in the cavity of the upper valve body (10), the constant-differential pressure reducing valve is arranged in the cavity of the lower valve body (15), the flange surfaces of the upper valve body and the lower valve body are connected into a whole by a fastener, the central lines of the flange surfaces are on the same axis, and a certain oblique angle is formed between the flange surfaces and the horizontal axis of the water inlet and outlet holes, and the constant-differential pressure reducing valve is arranged behind the regulating valve; the regulating valve comprises a hand wheel (3), a guide sleeve (9), a valve rod (5), a valve clack (11), an upper valve cover (7) and a fastening nut (4); the fixed-differential pressure reducing valve comprises a slide valve (24), a spring (25), a diaphragm (28), a lower valve cover (18), an adjusting screw rod (19), an adjusting gasket (23), a pressure plate (26) and a compression nut (27).

2. The self-operated miter valve of claim 1, wherein: the lower end of the upper valve body (10) is a flange, an inner hole of the part protruding rightwards is a water inlet, a barrel body at the upper part is in a step shape with a small upper part and a big lower part, a pit is arranged at the bottom, an upper partition wall (W1) is arranged at the joint of the pit and an inner cavity at the upper part, a cylinder protruding upwards is arranged in the center of the upper partition wall (W1), a conical chamfer is arranged at the upper end of the inner hole of the cylinder, and a plurality of through holes (a) are arranged on the upper partition wall (W1; the upper hole of the stepped inner cavity is matched with the guide sleeve (9) in a sliding way; a valve rod (5) is screwed in an inner hole of the guide sleeve (9); the lower end of the valve rod (5) is screwed with a valve clack (11), and a conical table at the lower end of the valve clack (11) and a conical chamfer at the upper end of a cylindrical inner hole at the center of an upper partition wall (W1) form a valve port (V1) of the regulating valve.

3. The self-operated miter valve of claim 1, wherein: the upper end of the lower valve body (15) is provided with a flange, the inner hole of the left end protruding part is a water outlet hole, a lower partition wall (W2) is arranged between the upper cavity and the lower cavity, the center of the lower partition wall (W2) is provided with an inner hole consistent with the central line of the lower valve body (15), and the bottom wall is provided with a screw hole consistent with the central line of the lower valve body (15).

4. The self-operated miter valve of claim 3, wherein: the slide valve (24) is a cylinder with an outer convex ring in the middle, a thread is processed on the lower section of the outer cylinder on the upper side of the outer convex ring, a pressure plate (26) is sleeved on the thread and is screwed with a compression nut (27), and the excircle of the upper section is loosely matched with the inner hole of the central cylinder of the upper partition wall (W1); a plurality of uniformly distributed radial holes (d) are drilled above the cylinder wall at the lower side of the outer convex ring, the excircle of the lower section is loosely matched with the hole at the center of the lower partition wall (W2), and the slide valve (24) can freely move up and down in the two holes; an elastic retainer ring (22) for a shaft is arranged on the outer cylinder at the lower end of the slide valve (24); an adjusting shim 23 is provided between the shaft circlip 22 and the lower end face of the lower partition wall W2, and the preload of the spring 25 can be adjusted by changing the thickness thereof.

5. The self-operated miter valve of claim 4, wherein: a spring (25) is disposed between an upper flat surface of the lower partition wall (W2) and the outer convex ring of the spool valve (24).

6. The self-operated miter valve of claim 4, wherein: the inner ring of the diaphragm (28) is pressed between an outer convex ring of the slide valve (24) and a pressure plate (26) by a pressing nut (27), and a thickened ring on the outer edge of the outer ring is pressed between flanges of the upper valve body and the lower valve body by a fastening piece.

7. The self-operated miter valve of claim 1, wherein: a lower valve cover (18) is screwed in a screw hole on the bottom wall of the lower valve body (15), a stepped hole is formed in the center of the lower valve cover, and threads are processed in a smaller hole on the lower side of the lower valve cover; the adjusting screw (19) consists of a circular plate and a small shaft, the upper section of the small shaft is a cylinder and is matched with the larger inner hole of the lower valve cover (18) in a sliding way, the lower section of the small shaft is a screw and is screwed with the screw hole of the lower valve cover (18), the lower end of the screw is provided with a square opening for rotating the adjusting screw (19), and a locking nut (20) is screwed on the screw; the circular plate of the adjusting screw (19) and the annular end surface at the lower end of the slide valve (24) form a valve port (V2) of the constant-pressure-difference pressure-reducing valve.

8. A self-operated miter valve according to any of claims 1 to 7, wherein: the upper chamber (H5) of the diaphragm (28) is communicated with the water inlet chamber (H1) through the through hole (a), so that the water pressure in the upper chamber (H5) is equal to the water inlet pressure, namely the pre-valve pressure (P1) of the regulating valve; the lower chamber (H4) of the diaphragm (28) communicates with the intermediate chamber (H2) through the radial holes (d), so that the water pressure in the lower chamber (H4) is equal to the regulator valve back pressure (P2).

Technical Field

The invention relates to the technical field of valves, in particular to a self-operated bevel valve.

Background

In a piping system for conveying a liquid medium, a common regulating valve such as a ball valve or a butterfly valve is generally used to regulate a flow rate, but a regulating valve of this type used alone has a disadvantage in that when a pressure at an inlet or an outlet fluctuates, a change in a differential pressure across the regulating valve is caused, so that the flow rate through the regulating valve changes, which is undesirable in some cases, for example, in an air conditioning system, when a change in an amount of hot water or a coolant passing through the regulating valve occurs, a change in a temperature of a controlled environment is caused, causing a user to feel uncomfortable or wasting energy. This patent is designed in order to solve the above-mentioned technological not enough of ordinary governing valve, and its creativity is, establish ties a fixed difference pressure reducing valve behind ordinary governing valve, when the import or the outlet pressure of governing valve take place undulant, because the pressure compensation effect of fixed difference pressure reducing valve, consequently can guarantee that the pressure differential at governing valve both ends is unchangeable to guarantee that the flow that passes through is unchangeable, perhaps in certain discrepancy in elevation scope, even install the floor that the building is different, also can guarantee that the flow that passes through is unchangeable.

Disclosure of Invention

The invention aims to solve the problem that the flow rate passing through a regulating valve is easy to change when the pressure at the inlet or the outlet of the regulating valve fluctuates in a pipeline system for conveying liquid in the prior art, and provides a self-operated bevel valve which can automatically stabilize the pressure difference at two ends of the regulating valve so as to keep the flow rate passing through the regulating valve basically unchanged.

The invention adopts a specific technical scheme that the self-operated oblique angle valve comprises an adjusting valve and a fixed differential pressure reducing valve, wherein the adjusting valve is arranged in a cavity of an upper valve body, the fixed differential pressure reducing valve is arranged in a cavity of a lower valve body, flange surfaces of the upper valve body and the lower valve body are connected into a whole by a fastener, the central lines of the flange surfaces are on the same axis and have a certain oblique angle with the horizontal axis of a water inlet hole and a water outlet hole, and the fixed differential pressure reducing valve is arranged behind the adjusting valve; the regulating valve comprises a hand wheel, a guide sleeve, a valve rod, a valve clack, an upper valve cover, a fastening nut and the like; the fixed-differential pressure reducing valve comprises a slide valve, a spring, a diaphragm, a lower valve cover, an adjusting screw rod, an adjusting gasket, a pressing plate, a compression nut and the like. The invention comprises a regulating valve and a fixed-differential pressure reducing valve, and the position of a valve clack can be changed by rotating a valve rod through a hand wheel, thereby realizing the function of regulating or closing flow; the constant-differential pressure reducing valve can automatically adjust the opening degree of a valve port of the constant-differential pressure reducing valve through the up-and-down movement of the slide valve according to the change of the pressure difference on two sides of the diaphragm, so that the pressure at the outlet end of the regulating valve is compensated, the pressure difference at two ends of the regulating valve can be kept unchanged, and the flow passing through the regulating valve is ensured to be unchanged.

Preferably, the lower end of the upper valve body is provided with a flange, an inner hole of the part protruding rightwards is provided with a water inlet, a barrel body at the upper part is in a step shape with a small upper part and a big lower part, the bottom of the barrel body is provided with a pit, an upper partition wall is arranged at the joint of the pit and an inner cavity at the upper part, a cylinder protruding upwards is arranged in the center of the upper partition wall, the upper end of the inner hole of the cylinder is provided with a conical chamfer, and the upper partition; the upper hole of the stepped inner cavity is matched with the guide sleeve in a sliding way; a valve rod is screwed in an inner hole of the guide sleeve; the lower end of the valve rod is screwed with a valve clack; the valve port of the regulating valve is formed by the frustum at the lower end of the valve clack and the conical chamfer at the upper end of the cylindrical inner hole in the center of the upper partition wall.

Preferably, the upper end of the lower valve body is provided with a flange, an inner hole of the left end protruding part is provided with a water outlet hole, a lower partition wall is arranged between the upper cavity and the lower cavity, the center of the lower partition wall is provided with an inner hole consistent with the central line of the lower valve body, and the bottom wall is provided with a screw hole consistent with the central line of the lower valve body.

Preferably, the slide valve is a cylinder with an outer convex ring in the middle, threads are processed on the lower section of the outer cylinder on the upper side of the outer convex ring, a pressing plate is sleeved on the threads and a pressing nut is screwed on the threads, and the upper section of the slide valve is loosely matched with an inner hole of the cylinder in the center of the upper partition wall; a plurality of uniformly distributed radial holes are drilled above the cylinder wall on the lower side of the outer convex ring, the excircle of the lower section is loosely matched with the hole in the center of the lower partition wall, and the slide valve can freely move up and down in the two holes; an elastic retainer ring for a shaft is arranged on the outer cylinder at the lower end of the sliding valve; an adjusting gasket is arranged between the elastic retainer ring for the shaft and the lower end face of the lower partition wall, and the prepressing force of the spring can be adjusted by changing the thickness of the adjusting gasket.

Preferably, the spring is disposed between an upper plane of the lower partition wall and the outer collar of the slide valve.

Preferably, the inner ring of the diaphragm is pressed between the outer convex ring of the slide valve and the pressure plate by a pressing nut, and the thickened ring on the outer edge of the outer ring is pressed between the flanges of the upper valve body and the lower valve body by a fastening piece. The diaphragm drives the slide valve to move upwards or downwards along with the change of the pressure difference between the upper cavity and the lower cavity, and the opening degree of the valve port of the fixed-difference pressure-reducing valve is correspondingly adjusted.

Preferably, a lower valve cover is screwed in a screw hole in the bottom wall of the lower valve body, a stepped hole is formed in the center of the lower valve cover, and threads are machined in a smaller hole in the lower side of the lower valve cover; the adjusting screw rod consists of a circular plate and a small shaft, the upper section of the small shaft is a cylinder and is matched with the larger inner hole of the lower valve cover in a sliding way, the lower section of the small shaft is a screw rod and is screwed with the screw hole of the lower valve cover, a square opening for rotating the adjusting screw rod is arranged below the screw rod, and a locking nut is screwed on the screw rod; the circular plate of the adjusting screw and the annular end face at the lower end of the slide valve form a valve port of the constant-differential pressure reducing valve.

Preferably, the upper cavity of the diaphragm is communicated with the water inlet cavity through the through hole, so that the water pressure in the upper cavity is equal to the water inlet pressure, namely the pressure before the valve of the regulating valve; the lower cavity of the diaphragm is communicated with the middle cavity through the radial hole, so that the water pressure in the lower cavity is equal to the pressure behind the regulating valve.

The invention has the beneficial effects that: the self-operated bevel valve effectively solves the problem that the system state is changed due to the change of the flow of the regulating valve when the pressure of the inlet or the outlet of the regulating valve fluctuates in the pipeline system for conveying liquid in the prior art, and can automatically stabilize the pressure difference at two ends of the regulating valve, so that the flow in the pipeline system is basically kept unchanged.

Drawings

Fig. 1 is a schematic structural diagram of a self-operated bevel valve according to the present invention.

In the figure: 1. the valve comprises a fixed nut, 2, a gasket, 3, a hand wheel, 4, a clamping nut, 5, a valve rod, 6, a first O-shaped sealing ring, 7, an upper valve cover, 8, a second O-shaped sealing ring, 9, a guide sleeve, 10, an upper valve body, 11, a valve clack, 12, a third O-shaped sealing ring, 13, a screw, 14, an elastic cushion, 15, a lower valve body, 16, a fourth O-shaped sealing ring, 17, a fifth O-shaped sealing ring, 18, a lower valve cover, 19, an adjusting screw rod, 20, a locking nut, 21, a sixth O-shaped sealing ring, 22, an elastic shaft check ring, 23, an adjusting gasket, 24, a sliding valve, 25, a spring, 26, a pressure plate, 27, a compression nut, 28, a diaphragm, a through hole, d radial hole, delta, opening degree of a valve port of a constant-differential pressure reducing valve, delta, thickness of an adjusting gasket, W1, an upper partition wall, W2, a lower partition wall, V1, valve port, h1, water inlet chamber, h2, middle chamber, H3. water outlet chamber, H4. lower chamber, H5. upper chamber, p1, water inlet chamber pressure, p2, middle chamber pressure, and p3, water outlet chamber pressure. T1, a first detection screw hole, T2, a second detection screw hole.

Detailed Description

The following description will further explain the embodiments of the present invention by way of examples, with reference to fig. 1.

The longitudinal section of the patent refers to fig. 1, which comprises a regulating valve and a constant pressure reducing valve, wherein the regulating valve is arranged in the cavity of an upper valve body 10, the constant pressure reducing valve is arranged in the cavity of a lower valve body 15, the lower flange of the upper valve body 10 and the upper flange of the lower valve body 15 are connected into a whole by a plurality of screws 13 and elastic cushions 14, and the central lines of the connected two valve bodies are on the same axis and have a certain oblique angle with the horizontal axes of a water inlet and a water outlet. The lower end of the upper valve body 10 is provided with a flange; an inner hole on the right convex part is a water inlet hole; the upper part is a stepped cylinder with a small upper part and a large lower part; the bottom of the cylinder is provided with a pit, the joint of the pit and the upper inner cavity is provided with an upper partition wall W1, the center of the upper partition wall W1 is provided with a cylinder which protrudes upwards, the lower end of the inner hole of the cylinder is provided with a groove for installing a third O-shaped sealing ring 12, the upper end of the inner hole of the cylinder is provided with a conical chamfer which is used as a valve seat of a valve port V1 of the regulating valve, the central line of the cylinder is consistent with the central line of the upper valve body 10, and the upper partition wall W1 on the periphery of; a guide sleeve 9 is slidably arranged in a small hole at the upper part of the stepped inner cavity, an O-shaped sealing ring II 8 is arranged at the matching position, threads are processed at the upper end of an outer cylinder of the small hole and are screwed with the threads in the outer ring of the upper valve cover 7, and an outer convex ring above the guide sleeve 9 is pressed at the top end of the upper valve body 10; the inner hole of the guide sleeve 9 is in a step shape, the inner hole of the upper section is larger, a groove provided with a first O-shaped sealing ring 6 is machined in a proper position of the hole wall, the lower section is a thread, and a groove provided with a second O-shaped sealing ring 8 is machined on the excircle of the guide sleeve 9. A cylinder in the middle of the valve rod 5 is matched with an inner hole in the upper section of the guide sleeve 9 in a sliding manner; the screw rod at the middle lower part is screwed with the internal thread of the guide sleeve 9; a valve clack 11 is screwed on the stud at the lower part, the lower end of the valve clack 11 is provided with a frustum with a slightly larger diameter as the valve clack of the regulating valve, and the cone angle of the frustum is consistent with the cone chamfer angle above the inner hole of the upper cylinder of the upper partition wall W1; the upper section of the valve rod 5 is provided with a screw rod and a square opening, the screw rod passes through a hole on the top cover of the upper valve cover 7 and is screwed with a tightening nut 4 with a surface knurl, the square opening is provided with a hand wheel 3, and the screw rod at the top end is sleeved with a gasket 2 and is screwed with a fixing nut 1 for fixing the hand wheel 3.

The upper end of the lower valve body 15 is provided with a flange, an inner hole on the left end protruding part is a water outlet hole, and the water outlet hole and the water inlet hole are on the same horizontal axis; a lower partition wall W2 is arranged between the upper cavity and the lower cavity, the center of the lower partition wall W2 is provided with an inner hole consistent with the central line of the lower valve body 15, and a groove of the inner hole is provided with a fourth O-shaped sealing ring 16; the bottom wall has a threaded hole which is aligned with the center line of the lower valve body 15. The slide valve 24 is a cylinder with a convex ring in the middle; threads are processed on the lower section of the outer cylinder on the upper side of the outer convex ring, and the upper section of the outer convex ring is loosely matched with an inner hole of the upper cylinder of the upper partition wall W1; a plurality of uniformly distributed radial holes d are drilled on the upper section of the cylinder wall on the lower side of the outer convex ring, the outer diameter of the lower section of the cylinder wall is loosely matched with the holes on the lower partition wall W2, and the slide valve 24 can freely move up and down in the two holes; a groove for mounting the circlip 22 is formed on the outer circumference of the lower end of the spool 24 to limit the upward movement distance of the spool 24. An adjustment washer 22 is provided between the lower end surface of the lower partition wall W2 and the circlip 22 for shaft. The spring 25 is disposed between the upper flat surface of the lower partition wall W2 and the outer convex ring of the spool valve 24. The inner ring of the flexible membrane 28 is pressed between the convex ring of the slide valve 24 and the pressure plate 26 by the round nut 27, the thickened ring of the outer ring is pressed in the groove of the lower plane of the lower flange of the upper valve body 10 and the upper plane of the upper flange of the lower valve body 15 by the screw 13 and the elastic cushion 14, and the thickened ring plays a role in sealing. A lower valve cover 18 is arranged in a screw hole in the bottom wall of the lower valve body 15, an O-shaped sealing ring five 17 is arranged in the screw hole, the central line of the lower valve cover 18 is consistent with the central line of the lower valve body 15, a stepped hole is formed in the center of the lower valve cover 18, a groove provided with an O-shaped sealing ring six 21 is machined in the upper position of the larger hole in the upper side, and threads are machined in the small hole in the lower side. The adjusting screw rod 19 consists of a circular plate and a small shaft which is positioned in the center of the circular plate and is vertical to the circular plate, the upper side of the small shaft is a cylinder and is matched with a larger hole in the lower valve cover 18 in a sliding way, the screw rod at the lower side is screwed with the thread in the lower valve cover 18, and a square opening for rotating the adjusting screw rod 19 is arranged below the screw rod; the circular plate of the adjusting screw 19 and the annular end surface at the lower end of the slide valve 24 form a valve port V2 of the constant-pressure-difference pressure-reducing valve, the opening delta of the valve port V2 can be adjusted by rotating the adjusting screw 19, and the valve port delta is locked by a locking nut 20 after meeting the requirement. Six O-shaped sealing rings are used for preventing the internal leakage or the external leakage of the medium. A first detection screw hole T1 is drilled on the water inlet channel of the upper valve body 10, and a second detection screw hole T2 is drilled on the wall of the lower cavity part of the diaphragm 28 of the lower valve body 15 and used for connecting a pressure difference meter when measuring or adjusting the pressure difference between P1 and P2 and plugging the pressure difference meter by a plug at ordinary times. The connection mode of the water inlet hole and the water outlet hole with corresponding pipelines is that the water inlet hole and the water outlet hole are connected by threads for small caliber and connected by flanges for larger caliber.

Five cavities are formed in the valve body, the cavity between the water inlet hole and the valve port V1 is a water inlet cavity H1, and the water pressure is the water inlet pressure, namely the pre-valve pressure P1 of the valve is adjusted; the cavity between the valve port V1 and the valve port V2 is an intermediate cavity H2, and the pressure is the post-valve pressure P2 of the regulating valve; the cavity above the diaphragm 28 is an upper chamber H5, and since it communicates with the water inlet chamber H1 through the through hole a, the pressure in the upper chamber H5 is equal to the water inlet pressure P1; the cavity below the diaphragm 28 is the lower chamber H4, the pressure in the lower chamber H4 being equal to the post-valve pressure P2 of the regulating valve, due to the communication with the intermediate chamber H2 through the radial holes d; the cavity between the valve port V2 and the water outlet hole is a water outlet cavity H3, and the pressure is water outlet pressure P3.

The working principle of the invention is as follows:

the hand wheel 3 is rotated, the valve rod 5 can move up and down in the guide sleeve 9, and the valve clack 11 is driven to lift, so that the opening degree of the valve port V1 of the regulating valve is changed to regulate the passing flow, after the opening degree of the valve port V1 is determined, the valve port V3526 is locked by the clamping nut 4, and the valve port V1 can be closed if necessary.

Before water is supplied, the slide valve 24 is at the highest position under the action of the spring 25, as shown in FIG. 1, and the opening degree delta of the valve port V2 is at the maximum at the moment; after water is supplied, the pressure water P1 in the inlet cavity H1 enters the upper cavity H5 through the through hole a and acts on the upper part of the diaphragm 28; meanwhile, the post-valve pressure P2 of the regulating valve enters the lower cavity H4 through the radial hole d and acts below the diaphragm 28, because the opening Δ of the valve port V2 is large at this time, and the throttling and depressurizing effects are weak, the pressure P2 is low, so the spool 24 moves downward, the opening Δ of the valve port V2 gradually decreases, the throttling and depressurizing effects gradually increase, the pressure P2 of the intermediate cavity H2 gradually increases, when the force acting on the upper and lower parts of the spool 28 and the set force of the spring 25 are balanced, the spool 24 is in an ideal design position, and the differential pressure across the regulating valve is Δ P = F/S at this time (see the following calculation).

When the water inlet pressure P1 rises, the thrust acting above the diaphragm 28 is increased, the stress balance of the slide valve 24 is broken, the slide valve 24 moves downwards, the opening degree delta of the valve port V2 is reduced, the throttling and pressure reducing effects are increased, the pressure P2 of the intermediate cavity H2 rises along with the increase, and the pressure delta P = P1-P2 is kept unchanged; conversely, when the inlet pressure P1 decreases, the thrust acting above the diaphragm 28 decreases, the spool 24 moves upward under the urging of the spring 25, the opening degree of the valve port V2 increases, the throttling and pressure-reducing effect decreases, and the pressure P2 of the intermediate chamber H2 decreases accordingly, so that Δ P = P1-P2 remains unchanged.

When the outlet water pressure P3 of the outlet water cavity H3 rises, the slide valve 24 does not act in time at the moment of rising, so the pressure P2 of the intermediate cavity H2 rises synchronously, the thrust acting below the diaphragm 28 increases, the slide valve 24 is pushed to move upwards, the opening degree of the valve port V2 increases, the throttling and pressure reducing effects are weakened, the pressure P2 of the intermediate cavity H2 decreases along with the pressure P2 until the pressure returns to the original value, and the delta P = P1-P2 is kept unchanged. Conversely, when the outlet water pressure P3 decreases, the pressure P2 of the intermediate chamber H2 decreases synchronously, the spool 24 moves downward, the opening degree of the valve port V2 decreases, the throttling and pressure reducing effect increases, and the pressure P2 of the intermediate chamber H2 increases along with the decrease until the value returns to the original value, so that Δ P = P1-P2 is kept constant.

From the above analysis, it can be known that, in normal water supply, the pressure water in the water inlet chamber H1 is supplied to the downstream through the regulating valve port V1, the intermediate chamber H2, the constant-differential-pressure reducing valve port V2 and the water outlet chamber H3. When the pressure of the water inlet cavity or the water outlet cavity fluctuates, the pressure at the outlet end of the regulating valve is compensated by the constant-pressure-difference pressure reducing valve, so that the pressure difference at two ends of the regulating valve can be kept unchanged, and the flow passing through the regulating valve is ensured to be unchanged.

The pressure difference value at the two ends of the regulating valve can be set according to requirements by regulating the pre-pressure of the spring 25, the thickness delta of the regulating gasket 23 is changed, namely the spring 25 can be compressed or relaxed, so that the pre-pressure of the spring 25 is set, the thickness delta of the regulating gasket 23 is set when a product leaves a factory, and the thickness of the gasket 23 can be properly thickened when the rigidity of the spring is reduced after the regulating gasket is used for a long time.

The pressure difference across the regulator valve after water flow is calculated as follows.

When the spool 24 is in the equilibrium position, the force balance equation for the spool 24 is:

P1*S+G±Fm=P2*S+k*（X₀+X）

namely: (P1-P2) S = k (X)₀+X）-G±Fm……（1）

In the formula:

p1-pressure before regulating valve (Pa)

P2-pressure after regulating valve (Pa)

S-effective stress area of diaphragm (m)

G-weight (kg) of slide valve and related parts

Fm-Friction force (N) when slide valve moves

k-spring rate (N/m)

X₀-setting the compression (m) of the spring under pressure difference

When the pressure before or after the valve of the X-adjusting valve changes, the additional fluctuation amount (m) of the spring can be positive or negative.

For the sake of simplicity of calculation, the weight G and the friction Fm of the slide valve and the related parts are negligible, since they are small with respect to the pre-stress of the spring, and the expression (1) can be simplified to the point where it is negligible

P1-P2=k*X₀/S+ k*X/S……（2）

The design adopts a larger membrane area S, a smaller spring rate k and a larger compression amount X₀And when the pressure before or after the valve is adjusted is changed, the additional fluctuation quantity X of the spring is smaller, so the k X/S term in the formula (2) can be ignored, and the formula (2) can be simplified as follows:

P1-P2=k*X₀/S=F/S……（3）

wherein F = k X₀Namely the pre-pressure (N) of the spring under the set pressure difference.

As can be seen from equation (3), the differential pressure Δ P = P1-P2= F/S across the regulator valve after the water is supplied, and this differential pressure value is a constant value because it is related only to the pre-pressure of the spring and the diaphragm area.