CN214616969U

CN214616969U - Pressure limiting structure of flow control pump

Info

Publication number: CN214616969U
Application number: CN202120689566.5U
Authority: CN
Inventors: 周如景
Original assignee: Zhongshan Willpower Motor & Electric Appliance Co ltd
Current assignee: Zhongshan Willpower Motor & Electric Appliance Co ltd
Priority date: 2021-04-06
Filing date: 2021-04-06
Publication date: 2021-11-05
Anticipated expiration: 2031-04-06

Abstract

The utility model relates to a pressure limiting structure of a flow control pump, which comprises a pump head body, wherein a first water inlet cavity, a pressurizing cavity and a water outlet cavity are arranged in the pump head body, the first water inlet cavity and the water outlet cavity are respectively communicated with a first water inlet and a water outlet, the flow control pump also comprises a negative pressure valve seat, a vacuum cavity is arranged in the negative pressure valve seat, a second water inlet cavity is also arranged in the pump head body, the vacuum cavity is communicated with the second water inlet cavity through a water inlet flow passage, the second water inlet cavity is communicated with the pressurizing cavity through a one-way water flow control structure, a first sealing ring and a flow control component for controlling the waterway sealing or conduction at the first sealing ring are formed on a waterway communicated with the first water inlet cavity and the vacuum cavity, and a pressure limiting structure is arranged on a water path between the water outlet cavity and the water outlet, and the pressure limiting structure is communicated with the atmosphere through an air hole in the negative pressure valve seat body and is sealed or communicated with the second water inlet cavity through a water sealing assembly. The utility model discloses the control to output water pressure that can be better, go out difficult suppressing of water cavity department and press, voltage limiting simple structure.

Description

Pressure limiting structure of flow control pump

Technical Field

The utility model relates to a fluid conveying equipment technical field especially relates to a pressure limiting structure of accuse flow pump.

Background

The water supply pump is used as an important device for doing work on fluid in the fluid conveying process, and is widely applied to the existing industrial production and human life.

When the existing water dispenser uses a water supply pump, a normal pressure water tank is usually arranged, and the water supply pump pumps water from the normal pressure water tank and supplies water to a heating unit. When the water dispenser system is not provided with the normal-pressure water tank and a pressure water source is used for supplying water to the heating unit instead, the function of the water supply pump is insufficient, the water supply pump in the water dispenser industry needs to be added with a stopping function and a flow regulating function, and meanwhile, the water outlet also has a pressure relief function, so that the damage of a pressurizing diaphragm caused by long-time pressure build-up is avoided.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a be applicable to have pressure and non-pressure water source and the hydraulic accuse flow pump of accessible voltage limiting structure control output, when accuse flow pump operation, output water pressure can not surpass and set for the water pressure value.

In order to solve the technical problem, the utility model discloses a following scheme:

a pressure limiting structure of a flow control pump comprises a pump head body, a first water inlet cavity, a pressurizing cavity and a water outlet cavity are arranged in the pump head body, the first water inlet cavity and the water outlet cavity are respectively communicated with a first water inlet and a water outlet, the flow control pump also comprises a negative pressure valve seat, a vacuum cavity is arranged in the negative pressure valve seat, a second water inlet cavity is also arranged in the pump head body, the vacuum cavity is communicated with the second water inlet cavity through a water inlet flow channel, the second water inlet cavity is communicated with the pressurizing cavity through a one-way water flow control structure, a first sealing ring and a control rod matched with the first sealing ring are formed on a waterway communicated with the first water inlet cavity and the vacuum cavity to form a flow control assembly capable of sealing or communicating the waterway, and a pressure limiting structure is arranged on a water path between the water outlet cavity and the water outlet, and the pressure limiting structure is communicated with the atmosphere through an air hole in the negative pressure valve seat body and is sealed or communicated with the second water inlet cavity through a water sealing assembly.

By adopting the technical scheme, when source water is conveyed to the water outlet through the pressurizing cavity, the pressure value of the water outlet is changed under the action of the front valve, part of the water enters the second water inlet cavity through the water sealing assembly again, enters the pressurizing cavity through the one-way water flow structure and then enters the water outlet cavity through the pressurizing cavity, so that backflow water can be formed at the water outlet, the pressure value at the water outlet cannot exceed the preset value, and the water pressure at the output end can be effectively controlled.

Preferably, the pressure limiting structure comprises an air cavity, a pressure-holding cavity, a water return flow channel, a water discharge opening and a water sealing assembly located in the air cavity, the water sealing assembly comprises a pressure limiting spring, a pressure limiting diaphragm and a water sealing convex ring, the air cavity is defined by a negative pressure valve seat body and a cavity on a pump head body, the air cavity is communicated with the atmosphere through an air hole, the water return flow channel is communicated with a second water inlet cavity, the water discharge opening is communicated with a water outlet, the water path where the pressure-holding cavity is communicated with the water return flow channel is formed by the pump head body, the pressure limiting diaphragm is arranged at the water sealing convex ring, the periphery of the pressure limiting diaphragm is tightly pressed between the pump head body and the negative pressure valve seat in a sealing mode, the pressure limiting spring is located in the air cavity, one end of the pressure-holding cavity acts on the inner wall of the air cavity, and the other end of the pressure limiting diaphragm acts on the pressure limiting diaphragm.

Since the technical scheme is used, compare with ordinary accuse pump, the utility model discloses when delivery port pressure value is great, the intracavity is suppressed to the water in the outlet through the outlet entering suppress pressure, suppress intracavity water pressure and overcome the elasticity of pressure limiting spring and upwards open the pressure limiting diaphragm when suppressing pressure, make the pressure limiting diaphragm remove the sealed to water convex ring department, the water in the suppression intracavity gets into the second inlet chamber once more through the return water runner, the backward flow that the second inlet chamber was held between the fingers gets into the pressure boost chamber, transport to the outlet chamber by the pressure boost chamber again, just so become the backward flow through pressure limiting structure to some water of outlet, the water pressure of delivery port has effectively been restricted, simple efficient control output water pressure.

Preferably, the contact area of the pressure limiting diaphragm and the pressure building cavity is larger than that of the pressure limiting diaphragm and the water sealing convex ring. The pressure value of the pressure limiting diaphragm pushed open in the pressure holding cavity can realize backflow under the condition of smaller pressure, and the control of the output water pressure is facilitated.

Preferably, the flow control assembly comprises a control rod, a return spring and a pressure sensing diaphragm, the periphery of the pressure sensing diaphragm is hermetically fixed between the negative pressure valve seat and the valve cover, the pressure sensing diaphragm and the valve cover form an atmospheric cavity, and the valve cover is provided with an atmospheric hole; the side wall of the control rod is provided with a flow limiting groove, one end of the control rod is fixedly connected with the middle part of the pressure sensing diaphragm, and the other end of the control rod seals the first sealing ring; one end of the return spring acts on the control rod, the other end acts on the inner wall of the negative pressure valve seat, and the control rod forms a sealing water lantern ring or a flow control assembly for controlling the conduction of the sealing water lantern ring under the combined action of air pressure in the atmosphere cavity, pressure in the vacuum cavity and the return spring.

The related components of the existing water supply pump only have the function of water cut-off and do not have the function of regulating output flow under the condition of a pressure water source, the scheme arranges a vacuum cavity communicated with a second water inlet cavity in a negative pressure valve seat, when the flow control pump does not work, the flow control assembly controls the water path at the water sealing sleeve ring to be sealed, when the booster pump works, water flow or air in the vacuum cavity is sucked away to form a certain vacuum degree, at the moment, the flow control assembly controls the water path at the first sealing ring to be communicated, the flow after conduction is related to the vacuum degree in the vacuum cavity, the higher the vacuum degree is, the larger the flow after conduction is, the smaller the vacuum degree is, the smaller the flow after conduction is, the vacuum degree in the vacuum cavity can be adjusted when the water supply pump works by adjusting the working voltage (power) of the water supply pump, consequently adopt the utility model discloses a structural design can be in order to adjust the output flow of accuse stream pump during operation through adjusting the operating voltage (power) of water supply pump.

Preferably, the return spring is arranged in the vacuum cavity, one end of the return spring acts on the control rod, and the other end of the return spring acts on the inner wall of the vacuum cavity.

Preferably, the periphery of the lower end of the control rod is in sealing connection with the water sealing port through a first sealing ring, and the first sealing ring is tightly pressed in a groove formed between the pump head body and the negative pressure valve seat. The sealing performance of control lever department is strengthened to first sealing washer, avoids the water of vacuum chamber to get into first intake antrum prematurely.

Preferably, a second sealing ring is arranged on the outer side of the first sealing ring, and the second sealing ring is tightly pressed in a groove formed between the pump head body and the negative pressure valve seat. The second sealing ring strengthens the sealing performance of the connection between the negative pressure valve seat and the pump head body.

Preferably, the pump head body is detachably connected with the negative pressure valve seat through a fastening screw. The pump head body and the negative pressure valve seat can be conveniently replaced and disassembled.

Preferably, a third sealing ring is sleeved on the outer side of the water inlet flow channel and is arranged between the pump head body and the negative pressure valve seat body in a sealing mode. The third sealing ring strengthens the sealing performance of the connection between the negative pressure valve seat and the pump head body.

Preferably, the pressurizing cavity is communicated with the water outlet cavity through a one-way water flow control structure. The one-way water flow control structure can effectively prevent water in the water outlet cavity from flowing backwards.

The utility model discloses beneficial effect who has:

1. the utility model discloses a set up the pressure limiting structure on the water route of play water cavity and delivery port, when the water pressure by pressure boost chamber to delivery port surpassed the pressure limiting value, the pressure limiting structure enabled the part to be located the water of delivery port department and gets into the second intake antrum once more to get into the pressure boost chamber through one-way rivers structure, get into out the water cavity by the pressure boost chamber again, make the partial hydroenergy of delivery port form the backward flow like this, make the pressure value of delivery port department can not surpass the default, can the water pressure of effective control output.

2. When the utility model does not work, the flow control component has the function of water cut-off; when the flow control pump works, the output flow of the flow control pump can be adjusted by adjusting the working voltage (power) of the flow control pump.

Drawings

Fig. 1 is a schematic structural view of a front view section of the present invention;

fig. 2 is a rear view structure diagram of the present invention;

FIG. 3 is a schematic structural diagram of a left side view section of the present invention;

fig. 4 is a schematic view of the structure a-a in fig. 3.

The labels in the figure and the corresponding part names: 01-a first water inlet, 02-a pump head body, 03-a second sealing ring, 04-a first sealing ring, 05-a valve cover, 06-a return spring, 07-a control rod, 08-a pressure sensing diaphragm, 09-a vacuum cavity, 10-a first water inlet cavity, 11-a negative pressure valve seat, 12-a water inlet channel, 13-a third sealing ring, 14-a second water inlet cavity, 15-a second water inlet, 16-a first one-way diaphragm, 17-a pressurizing cavity, 18-a pressurizing diaphragm, 19-a flow limiting groove, 20-a water outlet, 21-a water return channel, 22-a water sealing convex ring, 23-a pressure limiting diaphragm, 24-an air hole, 25-an air cavity, 26-a pressure limiting spring, 27-a water outlet, 28-a pressure holding cavity and 29-a bracket, 30-second one-way diaphragm, 31-water outlet cavity, 32-spring snap ring, 33-atmosphere cavity, 34-atmosphere hole and 35-fastening screw.

Detailed Description

The present invention will be described in further detail with reference to the following examples and drawings, but the present invention is not limited thereto.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", and the like indicate the position or positional relationship based on the position or positional relationship shown in the drawings, or the position or positional relationship which is usually placed when the product of the present invention is used, and the terms are only for convenience of description of the present invention and simplifying the description, but do not indicate or imply that the device or element to which the term refers must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

In the description of the present invention, it should be further noted that, unless otherwise explicitly specified or limited, the terms "disposed," "opened," "mounted," "connected," and "connected" are to be construed broadly, e.g., as either a fixed connection, a detachable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example 1

As shown in fig. 1-4, a pressure limiting structure of a flow control pump includes a pump body 02, a first water inlet cavity 10, a pressurizing cavity 17, a water outlet cavity 31 are provided in the pump body 02, the first water inlet cavity 10 and the water outlet cavity 31 are respectively connected to a first water inlet 01 and a water outlet 20, the flow control pump further includes a negative pressure valve seat 11, a vacuum cavity 09 is provided in the negative pressure valve seat 11, a second water inlet cavity 14 is further provided in the pump body 02, the vacuum cavity 09 is connected to the second water inlet cavity 14 through a water inlet channel 12, the second water inlet cavity 14 is connected to the pressurizing cavity 17 through a one-way water flow control structure (a first one-way diaphragm 16), a first sealing ring (04) and a flow control component for controlling the sealing or conduction of the water path are formed on the water path connected between the first water inlet cavity 10 and the vacuum cavity 09, a pressure limiting structure is provided on the water path between the water outlet cavity 31 and the water outlet 27, and the pressure limiting structure is respectively connected to the atmosphere through an air hole 24, a negative pressure valve seat 11, The drainage hole 20 on the body of the pump head body 02 is communicated with the water outlet cavity 31.

The working principle of the embodiment is as follows: the flow control pump is suitable for pressure and non-pressure water sources, and when the flow control pump does not work, the flow control assembly controls the waterway seal at the first sealing ring 04; when the flow control pump works, water flow or air in the vacuum cavity 09 is sucked away to form a certain vacuum degree, at the moment, the flow control assembly controls the water path of the first sealing ring 04 to be communicated, the communicated flow is related to the vacuum degree in the vacuum cavity 09, the higher the vacuum degree is, the larger the communicated flow is, the smaller the vacuum degree is, the smaller the communicated flow is, and the working voltage (power) of the booster pump can be adjusted to adjust the vacuum degree in the vacuum cavity 09 when the flow control pump works, so that the flow control pump can be adjusted by adjusting the working voltage (power) of the flow control pump; compared with the prior art, in the embodiment, the pressure limiting structures are arranged on the water paths of the water outlet cavity 31 and the water outlet 27, when the water pressure from the pressurizing cavity 17 to the water outlet 27 is too high to exceed a preset value, the pressure limiting structures can enable part of water in the water to enter the second water inlet cavity 14 again, enter the pressurizing cavity 17 through the communicated water path structure, and finally be conveyed to the water outlet cavity 31 by the pressurizing cavity 17 to form return water, so that part of water at the water outlet 27 can form return water, the pressure value at the position of the water outlet 27 cannot exceed the preset value, and the water pressure at the output end can be effectively controlled.

Example 2

As shown in fig. 1-4, the pressure limiting structure includes an air chamber 25, a pressure-holding chamber 28, a water return channel 21, a water discharge opening 20, and a water sealing assembly located in the air chamber 25, the water sealing assembly includes a pressure limiting spring 26, the pressure limiting diaphragm 23 and the water sealing convex ring 22, the air cavity 25 is enclosed by the cavity on the negative pressure valve seat 11 body and the pump head body 02 body, the air cavity 25 is communicated with the atmosphere through the air hole 24, the return water flow channel 21 is communicated with the second water inlet cavity 14, the water outlet 20 is respectively communicated with the pressure suppressing cavity 28 and the water outlet 27, the water way where the pressure suppressing cavity 28 is communicated with the return water flow channel 21 is formed by the pump head body 02 body, the water sealing convex ring 22 is formed by the pressure suppressing cavity 28 and the return water flow channel 21, the pressure limiting diaphragm 23 is arranged at the position of the water sealing convex ring 22, the periphery of the pressure limiting diaphragm is tightly pressed between the pump head body 02 and the negative pressure valve seat 11 in a sealing way, the pressure limiting spring 26 is positioned in the air cavity 25, one end of the pressure limiting diaphragm acts on the inner wall of the air cavity 25, and the other end of the pressure limiting diaphragm 23 acts on the pressure limiting diaphragm.

The specific working principle of this embodiment is as follows: after the water source of the pressurizing cavity 17 continuously enters the water outlet cavity 31, the water amount on the waterway from the water outlet cavity 31 to the water outlet 27 is continuously increased, when the water amount of the water outlet 27 is limited to be discharged, pressure is generated in the water outlet 27, at the moment, redundant water amount enters the pressure-holding cavity 28 through the water outlet 20, along with the continuous increase of the water amount in the pressure-holding cavity 28, the pressure begins to increase, the elastic force of the pressure-limiting spring 26 is overcome, the pressure-limiting diaphragm 23 releases the seal of the water-sealing convex ring 22, the water flow in the pressure-holding cavity 28 enters the second water inlet cavity 14 again, the water flow is conveyed into the pressurizing cavity 17 through the waterway structure communicated between the second water inlet cavity 14 and the pressurizing cavity 17, and finally conveyed to the water outlet cavity 31 through the pressurizing cavity 17, so that the water pressure of the water outlet 27 is controlled, the overpressure phenomenon cannot be generated at the water outlet 27, when the water pressure in the pressure-holding cavity 28 is not enough to overcome the elastic force of the pressure-limiting spring 26, the water sealing convex ring 22 is sealed under the combined action of the pressure limiting spring 26 and the pressure limiting diaphragm 23, the pressure relief backflow waterway is isolated, and water from the water outlet cavity 31 is normally discharged through the water outlet 27.

Example 3

As shown in fig. 1, in this embodiment, the contact area between the pressure limiting diaphragm 23 and the pressure building cavity 28 is larger than the contact area between the pressure limiting diaphragm 23 and the water sealing convex ring 22. The pressure value of the pressure limiting diaphragm required to be pushed open in the pressure-building cavity is smaller than the water pressure value in the water return flow channel, and the control of the output water pressure is facilitated.

Example 4

As shown in fig. 1-4, the flow control assembly includes a control rod 07, a return spring 06, and a pressure sensing diaphragm 08, the periphery of the pressure sensing diaphragm 08 is hermetically fixed between the negative pressure valve seat 11 and the valve cover 05, the pressure sensing diaphragm 08 and the valve cover 05 form an atmosphere cavity 33, and the valve cover 05 is provided with an atmosphere hole 34; a flow limiting groove 19 is formed in the side wall of the control rod 07, one end of the control rod 07 is fixedly connected with the middle part of the pressure sensing diaphragm 08, and the other end of the control rod 07 seals the first sealing ring 04; one end of the return spring 06 acts on the control rod 07, the other end acts on the spring snap ring (32) on the inner wall of the negative pressure valve seat (11), and the control rod 07 forms the first sealing ring 04 or the flow control assembly for controlling the conduction of the first sealing ring 04 under the combined action of the air pressure in the atmosphere cavity 33, the pressure in the vacuum cavity 09 and the return spring 06.

The specific working principle of this embodiment is as follows: when the flow control pump does not work, the sum of the acting force of the pressure in the vacuum cavity 09 and the elastic force of the return spring 06 on the pressure sensing diaphragm 08 is larger than the acting force of the air pressure in the atmosphere cavity 33 on the pressure sensing diaphragm 08, and the control rod 07 seals the first sealing ring 04 under the combined action of the acting forces; when the flow control pump works, water flow or air in the vacuum cavity 09 is sucked away to form a certain vacuum degree, at the moment, the sum of acting forces of the pressure in the vacuum cavity 09 and the elastic force of the return spring 06 on the pressure sensing diaphragm 08 is smaller than the acting force of the pressure in the atmosphere cavity 33 on the pressure sensing diaphragm 08, the control rod 07 moves downwards (in the direction of the first water inlet cavity 10) under the combined action of the acting forces, the fact that the flow limiting groove 19 is arranged on the side wall of the control rod 07 means that the lower end of the control rod 07 is not provided with the flow limiting groove 19, the side wall above the lower end is provided with the flow limiting groove 19, the part of the lower end of the control rod 07 without the flow limiting groove 19 completely moves downwards into the first water inlet cavity 10, and when the control rod continues to move downwards, the first water inlet cavity 10 is communicated with the vacuum cavity 09 through the flow limiting groove 19. When the flow limiting groove 19 of the control rod 07 just moves downwards into the first water inlet cavity 10, the flow channel of the first water inlet cavity 10 communicated with the vacuum cavity 09 through the flow limiting groove 19 is small, the flow rate pumped by the flow control pump is small, if the control rod 07 moves downwards continuously, the part of the control rod 07 with the flow limiting groove 19 moves downwards into the first water inlet cavity 10 for a longer distance, the flow channel area of the first water inlet cavity 10 communicated with the vacuum cavity 09 through the flow limiting groove 19 is increased, and the flow rate pumped by the flow control pump is increased. Therefore, by adjusting the working voltage (power) of the current control pump, the vacuum in the vacuum chamber 09 can be adjusted, and the distance of the control rod 07 moving downwards is adjusted, so that the function of adjusting the output flow of the current control pump is achieved.

Example 5

As shown in fig. 1, the return spring 06 is disposed in the vacuum chamber 09, and one end of the return spring 06 acts on the control rod 07, and the other end acts on the inner wall of the vacuum chamber 09.

Example 6

As shown in fig. 1, the periphery of the lower end of the control rod 07 is connected with the water sealing port in a sealing manner through a first sealing ring 04, and the first sealing ring 04 is tightly pressed and arranged in a groove formed between the pump head body 02 and the negative pressure valve seat 11. The first sealing ring 04 strengthens the sealing performance of the control rod 07, and prevents water in the vacuum cavity 09 from entering the first water inlet cavity 10 too early.

Example 7

As shown in fig. 1, a second sealing ring 03 is disposed on the outer side of the first sealing ring 04, and the second sealing ring 03 is tightly pressed in a groove formed between the pump head body 02 and the negative pressure valve seat 11. The second sealing ring 03 enhances the sealing performance of the connection between the negative pressure valve seat 11 and the pump head body 02.

Example 8

As shown in fig. 3, the pump head body 02 is detachably connected to the negative pressure valve seat 11 by a fastening screw 35. The pump head body 02 and the negative pressure valve seat 11 are convenient to replace and disassemble.

Example 9

As shown in fig. 1, a third sealing ring 13 is sleeved on the outer side of the water inlet flow passage 12, and the third sealing ring 13 is hermetically arranged between the body of the pump head body 02 and the body of the negative pressure valve seat 11. The third seal ring 13 enhances the sealing performance of the connection between the negative pressure valve seat 11 and the pump head body 02.

Example 10

As shown in FIG. 2, the pumping chamber 17 communicates with the outlet chamber 31 via a one-way flow control structure (second one-way diaphragm 30). The one-way water flow control structure can effectively prevent water in the water outlet cavity 31 from flowing backwards.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and the technical essence of the present invention is that within the spirit and principle of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments are all within the protection scope of the technical solution of the present invention.

Claims

1. A pressure limiting structure of a flow control pump comprises a pump body (02), wherein a first water inlet cavity (10), a pressurizing cavity (17) and a water outlet cavity (31) are arranged in the pump body (02), the first water inlet cavity (10) and the water outlet cavity (31) are respectively communicated with a first water inlet (01) and a water outlet (27), the flow control pump further comprises a negative pressure valve seat (11), a vacuum cavity (09) is arranged in the negative pressure valve seat (11), a second water inlet cavity (14) is also arranged in the pump body (02), the vacuum cavity (09) is communicated with the second water inlet cavity (14) through a water inlet flow channel (12), the second water inlet cavity (14) is communicated with the pressurizing cavity (17) through a one-way water flow control structure, a first sealing ring (04) and a control rod (07) matched with the first sealing ring are formed on a water path communicated with the first water inlet cavity (10) and the vacuum cavity (09), and a flow control assembly capable of sealing or conducting the water path at the place is formed, the water outlet structure is characterized in that a pressure limiting structure is arranged on a water path between the water outlet cavity (31) and the water outlet (27), and the pressure limiting structure is communicated with the atmosphere through an air hole (24) in the negative pressure valve seat (11) body and is sealed or communicated with the second water inlet cavity (14) through a water sealing component.

2. The pressure limiting structure of a flow control pump according to claim 1, wherein the pressure limiting structure comprises an air chamber (25), a pressure-holding chamber (28), a water return flow passage (21), a water discharge opening (20) and a water sealing component located in the air chamber (25), the water sealing component comprises a pressure limiting spring (26), a pressure limiting diaphragm (23) and a water sealing convex ring (22), the air chamber (25) is enclosed by a cavity on the body of the negative pressure valve seat (11) and the body of the pump head body (02), the air chamber (25) is communicated with the atmosphere through an air hole (24), the water return flow passage (21) is communicated with the second water inlet chamber (14), the water discharge opening (20) is respectively communicated with the pressure-holding chamber (28) and the water outlet (27), the water passage where the pressure-holding chamber (28) is communicated with the water return flow passage (21) is formed by the body of the pump head body (02), the pressure limiting diaphragm (23) is arranged at the position of the water sealing convex ring (22) and the periphery of the pressure-holding pump is sealed and pressed against the negative pressure pump head body (02) and the valve seat (11), and the water valve seat (11) The pressure limiting spring (26) is positioned in the air cavity (25), one end of the pressure limiting spring acts on the inner wall of the air cavity (25), and the other end of the pressure limiting spring acts on the pressure limiting diaphragm (23).

3. The pressure limiting structure of a flow control pump according to claim 2, wherein the contact area of the pressure limiting diaphragm (23) and the pressure holding cavity (28) is larger than the contact area of the pressure limiting diaphragm (23) and the water sealing convex ring (22).

4. The pressure limiting structure of a flow control pump according to claim 1, wherein the flow control assembly comprises a control rod (07), a return spring (06) and a pressure sensing diaphragm (08), the periphery of the pressure sensing diaphragm (08) is hermetically fixed between a negative pressure valve seat (11) and a valve cover (05), the pressure sensing diaphragm (08) and the valve cover (05) form an atmosphere cavity (33), and the valve cover (05) is provided with an atmosphere hole (34); a flow limiting groove (19) is formed in the side wall of the control rod (07), one end of the control rod (07) is fixedly connected with the middle part of the pressure sensing diaphragm (08), and the other end of the control rod seals the first sealing ring (04); one end of the return spring (06) acts on the control rod (07), the other end acts on the inner wall of the negative pressure valve seat (11), and the control rod (07) and the first sealing ring (04) form a flow control assembly under the combined action of the air pressure in the atmosphere cavity (33), the pressure in the vacuum cavity (09) and the return spring (06).

5. The pressure limiting structure of the flow control pump according to claim 4, wherein the return spring (06) is arranged in the vacuum chamber (09), one end of the return spring (06) acts on the control rod (07), and the other end of the return spring acts on the inner wall of the vacuum chamber (09).

6. The pressure limiting structure of the flow control pump according to claim 4, wherein the periphery of the lower end of the control rod (07) is connected with the water sealing port in a sealing manner through a first sealing ring (04), and the first sealing ring (04) is tightly pressed and arranged in a groove formed between the pump head body (02) and the negative pressure valve seat (11).

7. The pressure limiting structure of a flow control pump according to claim 6, wherein a second sealing ring (03) is arranged outside the first sealing ring (04), and the second sealing ring (03) is tightly pressed and arranged in a groove formed between the pump head body (02) and the negative pressure valve seat (11).

8. The pressure limiting structure of a flow control pump according to claim 1, wherein the pump head body (02) is detachably connected with the negative pressure valve seat (11) through a fastening screw (35).

9. The pressure limiting structure of a flow control pump according to claim 1, wherein a third sealing ring (13) is sleeved outside the water inlet flow channel (12), and the third sealing ring (13) is hermetically arranged between the body of the pump head body (02) and the body of the negative pressure valve seat (11).

10. A pressure limiting structure of a flow control pump according to claim 1, characterized in that the pressurizing chamber (17) is connected with the water outlet chamber (31) through a one-way water flow control structure.