CN209908678U - Piston plunger composite pump - Google Patents

Abstract

The utility model provides a piston plunger combination pump, include: the piston is positioned in the cylinder sleeve and divides the cylinder sleeve into a first cavity and a second cavity; the liquid inlet channel and the gas inlet channel are used for communicating the gas-liquid separation device with the cylinder sleeve; liquid inlets communicated with outlet ends of the liquid inlet channels and air inlets communicated with outlet ends of the air inlet channels are arranged on the first cavity at intervals; the piston respectively sucks liquid in the liquid inlet channel and gas in the gas inlet channel into the first chamber in a first stroke, and the pressure of the liquid inlet channel is higher than that of the gas inlet channel; and the piston is also used for discharging the gas-liquid mixture sucked into the first chamber into the second chamber in a second stroke. The utility model discloses a set up inlet channel and inlet channel alone and set up inlet pressure as being greater than inlet pressure, can guarantee in liquid and the gaseous homoenergetic gets into first cavity, prevent the emergence of air-resistor.

Description

Piston plunger composite pump

Technical Field

The utility model relates to an oil gas transport technical field especially relates to a piston plunger combination pump.

Background

Oil gas conveying is very important work in the production process of oil fields, and produced oil gas is pressurized by pressurizing equipment and then conveyed to various places through oil conveying pipelines.

In the prior art, a piston-plunger compound pump is generally adopted to pressurize oil gas; the piston plunger pump comprises a pressurizing cavity and a piston rod of which the bottom end is connected with a piston valve, the piston valve divides the pressurizing cavity into an upper cavity and a lower cavity, and the bottom of the lower cavity is also provided with a bottom valve. When the device works, the piston rod moves upwards, the piston valve is closed, the volume of the upper cavity is reduced, so that the medium in the upper cavity is pressurized and discharged, and meanwhile, the bottom valve is opened, and the medium enters the lower cavity; when the piston rod moves downwards, the piston valve is opened, the bottom valve is closed, and the medium in the lower cavity enters the upper cavity. The piston valve moves up and down continuously, thereby pressurizing the medium.

However, since the medium contains gas whose density is less than that of the liquid, when the piston rod of the piston-plunger compound pump moves upward, the gas in the medium is sucked into the lower cavity first, so that the pressure in the lower cavity is rapidly increased, and the liquid in the medium is difficult to enter the lower cavity, that is, the piston-plunger compound pump generates air resistance, so that the liquid in the medium cannot be pressurized.

SUMMERY OF THE UTILITY MODEL

The utility model provides a piston plunger combination pump to overcome current piston plunger combination pump and lead to the problem that the liquid in the medium can't get into the pump chamber smoothly because of very easily taking place the air lock.

The utility model provides a piston plunger combination pump, include:

a cylinder liner;

the piston is arranged in the cylinder sleeve and is used for dividing the cylinder sleeve into a first cavity and a second cavity;

the inlet ends of the liquid inlet channel and the gas inlet channel are communicated with a gas-liquid separation device; liquid inlets communicated with outlet ends of the liquid inlet channels and air inlets communicated with outlet ends of the air inlet channels are arranged in the first cavity at intervals;

the piston is used for sucking liquid in the liquid inlet channel and gas in the gas inlet channel into the first chamber in a first stroke, and the liquid inlet pressure of the liquid inlet channel is higher than the gas inlet pressure of the gas inlet channel; and a second chamber for discharging the gas-liquid mixture sucked into the first chamber into the second chamber in a second stroke.

Optionally, the inlet channel cover is established outside the inlet channel, the inlet encircles the air inlet setting.

Optionally, the first chamber is provided with a bottom valve seat, and the air inlet and the liquid inlet are both arranged on the bottom valve seat;

the air inlet is provided with a one-way air inlet valve, and the liquid inlet is provided with a one-way liquid inlet valve.

Optionally, the base valve seat comprises: the cover body is arranged close to the first cavity and fixed with the base body; the base body is provided with an air inlet used as the air inlet along the central axis direction, the liquid inlet comprises a plurality of liquid inlet holes arranged on the base body, and the liquid inlet holes are arranged around the air inlet;

the one-way intake valve includes: the air valve core is arranged in the air inlet and is connected with the cover body through the first elastic piece;

the one-way liquid inlet valve comprises: the liquid inlet valve plate is covered on the liquid inlet and is connected with the cover body through the second elastic piece.

Optionally, the cover body at least accommodates a portion of the seat body, and the cover body is provided with a through hole.

Optionally, the axial cross section of the inlet port includes a tapered portion, the valve spool is mounted in the tapered portion, and the tapered portion is adjacent to the first chamber.

Optionally, the exit direction of the liquid inlet hole and the central axis of the seat body are obliquely arranged, and the liquid is sprayed to the outer side of the central axis.

Optionally, the piston comprises a piston valve base, a resetting piece and a piston valve plate;

the piston valve base is provided with a plurality of piston holes around the axis of the piston valve base, the piston holes are used for the gas-liquid mixture in the first chamber to pass through, and the piston valve plate cover is arranged at one end of the piston hole facing the second chamber and is connected with the piston valve base through the resetting piece;

the outer side wall of the piston valve base is in sealing contact with the inner wall of the cylinder sleeve.

Optionally, a sealing ring is sleeved between the outer side wall of the piston valve base and the inner wall of the cylinder sleeve;

the outer side surface of the sealing ring is provided with a sawtooth structure, a part of sawteeth of the sawtooth structure incline towards the second chamber, and the rest of sawteeth of the sawtooth structure incline towards the first chamber.

Optionally, the piston-plunger compound pump comprises a plurality of cylinder sleeves and a piston arranged in each cylinder sleeve;

the initial position of each piston is different and each piston operates once in a time period.

The utility model provides a piston plunger combination pump, include: a cylinder liner; the piston is arranged in the cylinder sleeve and is used for dividing the cylinder sleeve into a first cavity and a second cavity; the inlet ends of the liquid inlet channel and the gas inlet channel are communicated with a gas-liquid separation device; the first cavity is provided with a liquid inlet communicated with the outlet end of the liquid inlet channel and a gas inlet communicated with the outlet end of the gas inlet channel at intervals; the piston is used for sucking liquid in the liquid inlet channel and gas in the gas inlet channel into the first chamber in a first stroke, and the pressure of the liquid inlet channel is higher than that of the gas inlet channel; and a second chamber for discharging the gas-liquid mixture sucked into the first chamber into the second chamber in a second stroke. The utility model is provided with the liquid inlet channel and the air inlet channel which are communicated with the first cavity of the cylinder sleeve, the inlet ends of the liquid inlet channel and the air inlet channel are respectively communicated with the gas-liquid separation device, the outlet ends of the liquid inlet channel and the air inlet channel are correspondingly communicated with the liquid inlet and the air inlet which are arranged on the first cavity at intervals, so that the liquid and the gas in the oil gas respectively and independently enter the first cavity through the liquid inlet channel and the gas inlet channel, compared with the existing piston plunger compound pump which only sucks oil liquid mixture through a single channel and is very easy to cause air resistance, the utility model can set the liquid inlet pressure to be larger than the gas inlet pressure, can guarantee in liquid and the gaseous homoenergetic gets into first cavity, effectually prevent to take place the air lock phenomenon because of gaseous first cavity of preferred entering more for liquid and gaseous homoenergetic in the oil gas obtain effectual pressure boost.

The structure of the present invention and other objects and advantages thereof will be more clearly understood from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.

Fig. 1 is a schematic structural diagram of a piston-plunger compound pump according to an embodiment of the present invention;

FIG. 2 is an enlarged partial schematic view of FIG. 1;

FIG. 3 is a cross-sectional view of the valve seat of the base valve of FIG. 2;

FIG. 4 is a bottom view of the cover of FIG. 3;

FIG. 5 is a schematic illustration of the piston valve of FIG. 2;

FIG. 6 is a left side view of FIG. 1;

FIG. 7 is a schematic structural view of the linkage mechanism of FIG. 1;

fig. 8 is a top view of fig. 1.

Description of reference numerals:

1-cylinder sleeve;

11 — a first chamber; 12 — a second chamber; 13-bottom valve seat; 14-air valve core; 15-a first elastic member; 16-liquid inlet valve plate; 17-a second elastic member; 18-cylinder liner seat ring;

121-oil drain port; 131-a seat body; 132-a cover; 133-a through hole;

111-liquid inlet; 112-an air inlet;

1121 — a tapered portion;

2, a piston;

21-piston valve base; 22-a reset member; 23-a piston valve plate; 24-a piston valve cap body; 25, sealing rings; 26-a piston rod;

211 — piston bore;

3-liquid inlet channel;

31-liquid inlet elbow pipe; 32-a compacting plate;

4-an air inlet channel;

41-central inlet pipe; 42-inlet elbow; 43 — gas distributor;

5, a liquid drainage channel;

51-a drainage box; 52-liquid discharge elbow pipe;

511-sealing the box body; 512-righting sleeve;

6, a transmission part;

61-crank; 62-a linkage mechanism; 63-stress frame; 64, a coupler; 65-power input shaft; 66-intermediate force transmission shaft; 67-disc axle; 68-a bearing seat; 69-bearing block support;

621-connecting rod; 622 — upper link pin; 623-lower link pin; 624-radial ball bearing; 625 — a guide rail; 631-a ball and socket washer;

7-cooling chamber;

8, reinforcing the bracket;

9, connecting the shaft;

10-connecting plate.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present application, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description of the present invention, it is to be understood that the terms "inner", "outer", "upper", "bottom", "front", "rear", and the like, when used in the positional or orientational relationships illustrated in fig. 1, are used only for convenience in describing the present invention and to simplify the description, and do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be considered as limiting the present invention.

Fig. 1 is a schematic structural diagram of a piston-plunger compound pump according to an embodiment of the present invention; fig. 2 is a partially enlarged schematic view of fig. 1. Referring to fig. 1 and 2, the present embodiment provides a piston plunger compound pump including: a cylinder liner 1; a piston 2 disposed in the cylinder liner 1 for partitioning the cylinder liner 1 into a first chamber 11 and a second chamber 12; the inlet ends of the liquid inlet channel 3 and the gas inlet channel 4 are communicated with a gas-liquid separation device; the first chamber 11 is provided with a liquid inlet 111 communicated with the outlet end of the liquid inlet channel 3 and a gas inlet 112 communicated with the outlet end of the gas inlet channel 4 at intervals; the piston 2 is used for sucking liquid in the liquid inlet channel 3 and gas in the gas inlet channel 4 into the first chamber 11 in a first stroke, and the pressure of the liquid inlet channel 3 is higher than that of the gas inlet channel 4; and for discharging the gas-liquid mixture sucked into the first chamber 11 into the second chamber 12 in the second stroke.

Specifically, the cylinder liner 1 may be manufactured by any suitable material through any existing suitable processing technology. For example, in some examples, the cylinder liner 1 may be formed from an alloy steel material, quenched and/or coated with a wear-resistant material, and ground to an inner wall finish of Ra0.2 to reduce wear of the inner wall of the cylinder liner 1 on the piston 2.

The gas-liquid separation device can be an oil-gas separation device commonly adopted in the existing oil-gas exploitation, and other oil-gas separation devices which are improved by a simple structure and are suitable for the physicochemical property of petroleum can be adopted. For example, the oil-gas separation device used in the laboratory can be used in the present embodiment after being scaled up to perform oil-gas separation. The inlet end of the liquid inlet channel 3 is communicated with a liquid outlet at the bottom of the gas-liquid separation device, and the inlet end of the gas inlet channel 4 is communicated with a gas outlet at the top of the gas-liquid separation device. During specific work, the liquid medium and the gas medium in the oil-gas mixture to be conveyed are separated by the gas-liquid separation device, then the liquid of the gas-liquid separation device is sucked into the first chamber 11 through the liquid inlet channel 3 under the action of the piston plunger composite pump, and meanwhile, the gas of the gas-liquid separation device is sucked into the first chamber 11 through the gas inlet channel 4, so that the liquid and the gas are subjected to pressurization treatment.

The specific working process of the piston-plunger compound pump of the embodiment is as follows: in the first stroke, the piston 2 moves upwards in the cylinder liner 1, the volume of the first chamber 11 is increased, the pressure in the first chamber 11 is reduced, the liquid in the liquid inlet channel 3 and the gas in the air inlet channel 4 are respectively sucked into the first chamber 11 through the liquid inlet 111 and the air inlet 112, simultaneously, the volume of the second chamber 12 is reduced, the pressure in the chamber is increased, the gas in the second chamber 12 is compressed and is preferentially discharged from the second chamber 12, and then the liquid in the second chamber 12 is also discharged from the second chamber 12 under the pushing of the piston 2; in the second stroke, the piston 2 moves downwards in the cylinder sleeve 1, the volume in the first chamber 11 is reduced, the pressure in the chamber is increased, the volume in the second chamber 12 is increased, the pressure in the chamber is reduced, the gas in the first chamber 11 is compressed and discharged out of the second chamber 12, the liquid in the first chamber 11 is also discharged into the second chamber 12 under the extrusion of the piston 2, the piston 2 reciprocates, and the conveyed oil gas is continuously sucked and discharged. It is emphasized that the piston 2 of this embodiment ensures that the inlet pressure is greater than the inlet pressure before it is operated. The liquid inlet pressure of the liquid inlet channel 3 can be increased, and/or the air inlet pressure of the air inlet channel 4 can be reduced, so that the liquid inlet pressure is greater than the air inlet pressure, and the liquid and the gas can enter the first chamber 11. In other examples, the structure of the intake passage 3 and the intake passage 4 may be optimized so that the intake pressure is higher than the intake pressure. The specific optimization method can refer to the method of adjusting the medium pressure in the pipeline in the prior art, for example, the method can be adjusted by the pressure control valve below, or the method can also be adjusted by the aperture sizes of the liquid inlet 111 and the gas inlet 112.

In order to ensure that the liquid in the liquid inlet channel 3 and the gas in the gas inlet channel 4 enter the first cavity 11 simultaneously, the gas is prevented from entering the first cavity 11 first to cause the phenomenon of gas resistance, and the liquid inlet pressure or the gas inlet pressure can be continuously adjusted according to actual conditions. For example, when it is found that liquid has entered the first chamber 11 and gas has not entered the first chamber 11, the intake pressure of the intake passage 12 may be increased to enable gas to enter the first chamber 11 in time. Wherein, whether in order to learn liquid and gas simultaneously to get into first cavity 11 in the first stroke in time, can set up cylinder liner 1 into transparent structure, can observe the motion state of liquid and gas in the cylinder liner 1 like this in real time, guarantee this piston plunger compound pump to the normal clear of the pressure boost operation of oil gas.

In addition, after the liquid and the gas are sucked into the first chamber 11 under the action of the piston, the gas is at the upper layer and the liquid is at the lower layer because the density of the gas is lower than that of the liquid, so that the sealing and the lubrication of the liquid to the bottom of the first chamber 11 in the second stroke are facilitated. Meanwhile, after the first stroke is finished, the gas is at the upper layer, the liquid is at the lower layer, after the second stroke is started, the piston 2 moves downwards, the gas in the first chamber 11 is firstly compressed, the volume of the liquid is unchanged, the compressed gas is preferentially discharged into the second chamber 12, and after the gas is completely discharged into the second chamber 12, the liquid is extruded into the second chamber 12 in the process that the piston 2 continuously moves downwards, so that the problem that the pump efficiency is reduced due to the fact that the gas, namely the clearance, exists in the liquid can be solved. Similarly, after the second stroke is completed, the gas in the second chamber 12 is located at the upper layer, the liquid in the second chamber 12 is located at the lower layer, after the first stroke of the next cycle is started, the piston 2 moves upwards, the gas in the second chamber 12 is firstly compressed, the volume of the liquid is unchanged, the compressed gas is preferentially discharged from the second chamber 12, the liquid is also extruded out of the second chamber 12 in the process that the piston 2 continuously moves upwards, the whole process realizes the independent pressurization and discharge of the gas and the liquid in the oil-gas mixture, and the working efficiency of the piston-plunger compound pump is improved.

Optionally, all be provided with pressure control valve at inlet end of inlet channel 3 and inlet channel 4 to conveniently adjust inlet pressure and inlet pressure at any time, make inlet pressure all can be greater than inlet pressure at the in-process of the whole first stroke of piston, thereby liquid in the better assurance inlet channel 3 and the gas in the inlet channel 4 all can get into first cavity 11 in, prevent that this piston plunger compound pump from taking place the air lock, thereby effectively avoided among the prior art because the defect in the unable entering cylinder liner of liquid in the oil gas that the air lock phenomenon caused.

This embodiment is through setting up inlet channel 3 and inlet channel 4 with the first cavity 11 intercommunication of cylinder liner 1 to communicate gas-liquid separation device respectively with this inlet channel 3 and inlet channel 4's entry end, correspond the intercommunication with inlet channel 3 and inlet channel 4's exit end on inlet 111 and the air inlet 112 that the interval was seted up on first cavity 11, make liquid and gas in the oil gas independently enter into first cavity 11 through inlet channel 3 and inlet channel 4 separately. Compare in current piston plunger compound pump and only inhale the fluid mixture through single passageway and appear the air lock phenomenon easily, this embodiment is higher than admission pressure through making admission pressure, guarantees in liquid and the gaseous homoenergetic gets into first cavity 11, the effectual air lock phenomenon of having prevented to take place because of gaseous light priority gets into in the first cavity 11 to make liquid and gaseous homoenergetic in the oil gas obtain effectual pressure boost.

The piston plunger compound pump of the embodiment can realize the purpose of directly pressurizing fluid with any oil-gas ratio from pure liquid to pure gas, meets the requirement of oil field production on oil-gas pressurizing and conveying, and overcomes the problem of air resistance in the prior art. Meanwhile, oil gas continues to be conveyed by the same pipeline after being pressurized by the piston plunger compound pump, a gas conveying pipeline and a liquid conveying pipeline are not required to be arranged, and the oil gas conveying cost is effectively reduced.

Wherein, the inlet channel 3 of this embodiment can overlap and establish outside inlet channel 4, and inlet 111 encircles air inlet 112 and sets up, sets up like this and makes inlet channel 3 parcel in inlet channel 4's periphery to make liquid encircle gaseous periphery and get into in the first cavity 11. The present embodiment prevents the gas from preferentially entering the first chamber 11 by setting the intake passage 4 at the center position to reduce the flow area of the intake passage 4, thereby reducing the amount of intake air of the intake passage 3.

In a specific implementation, the present embodiment may use a liquid inlet tank communicated with the liquid inlet on the first chamber 11 as the liquid inlet channel 3. In order to facilitate the liquid in the oil-gas separation device to enter the liquid inlet tank, a liquid inlet bent pipe 31 can be arranged on the liquid inlet tank, and the liquid inlet end of the liquid inlet bent pipe 31 is communicated with the liquid outlet of the gas-liquid separation device, so that the liquid in the gas-liquid separation device enters the liquid inlet tank through the liquid inlet bent pipe 31. The liquid inlet bent pipe 31 is detachably arranged on the liquid inlet box, so that the liquid inlet bent pipe 31 is convenient to detach and replace. Wherein, the pressure control valve can be arranged at the inlet end of the liquid inlet elbow 31.

The present embodiment may use, as the intake passage 4, an intake pipe that vertically passes through the bottom wall and the top wall of the liquid intake tank and communicates with the intake port 112 of the first chamber 11. In order to facilitate the assembly of the air inlet pipe, the air inlet pipe may include a central air inlet pipe 41 and an air inlet elbow 42, wherein the central air inlet pipe 41 is inserted into and fixed in the liquid inlet tank, and one end of the central air inlet pipe is communicated with the air inlet 112 of the first chamber 11, the other end of the central air inlet pipe is located outside the liquid inlet tank and detachably connected with one end of the air inlet elbow 42 (for example, flange connection, thread connection, etc.), and the inlet end of the air inlet elbow 42 is communicated with the air outlet of the oil-gas separation device. Because the central air inlet pipe 41 is fixedly connected in the liquid inlet tank, when the piston plunger compound pump is required to be communicated with the oil-gas separation device, only the two ends of the air inlet bent pipe 42 are simply communicated with the oil-gas separation device and the central air inlet pipe 41 respectively, the whole gas communication process is convenient and quick, and the assembly efficiency is effectively improved. Wherein the pressure control valve above may be provided at the inlet end of the inlet elbow 42.

In order to strengthen the connection stability between the central air inlet pipe 41 and the liquid inlet box, the pressing disc 32 can be sleeved in the through hole on the bottom wall of the liquid inlet box, the central air inlet pipe 41 penetrates and is fixed in the pressing disc 32, and the central air inlet pipe 41 is effectively prevented from being unstable in the liquid inlet box and influencing the tightness of the communication between the central air inlet pipe 41 and the air inlet 112.

The first chamber 11 of this embodiment is provided with a bottom valve seat 13, and the gas inlet 112 and the liquid inlet 111 are both arranged on the bottom valve seat 13; wherein, the air inlet 112 is provided with a one-way air inlet valve, and the liquid inlet 111 is provided with a one-way liquid inlet valve.

Specifically, the bottom valve seat 13 may be disposed at the bottom of the first chamber 11, the air inlet 112 disposed on the bottom valve seat 13 is communicated with the central air inlet pipe 41 of the air inlet channel 4, the top end is communicated with the first chamber 11, the bottom end of the liquid inlet 111 disposed on the bottom valve seat 13 is communicated with the liquid inlet tank 31 of the liquid inlet channel 3, the top end is communicated with the first chamber 11, and the liquid inlet 111 and the air inlet 112 are respectively and correspondingly disposed with a one-way liquid inlet valve and a one-way air inlet valve, so that in a first stroke of the piston 2, the liquid in the liquid inlet channel 3 and the gas in the air inlet channel 4 are sucked into the first chamber 11, and in a second stroke of the piston 2, the gas-liquid mixture in the first chamber 11 does not enter the liquid inlet channel 3 and the air inlet channel 4 through the liquid inlet 111 and the air inlet 112.

During specific work, in a first stroke, the piston 2 moves upwards, the volume in the first chamber 11 is increased, the pressure is reduced, the one-way liquid inlet valve is opened, and liquid in the liquid inlet channel 3 and gas in the gas inlet channel 4 respectively enter the first chamber 11 through the liquid inlet 111 and the gas inlet 112; in the second stroke, the piston 2 moves downwards, the volume in the first chamber 11 is reduced, the pressure is increased, the one-way liquid inlet valve is closed, the liquid inlet channel 3 and the gas inlet channel 4 are respectively isolated from the first chamber 11, so that the gas in the first chamber 11 is compressed by the piston 2 and is discharged into the second chamber 12, and then the liquid is discharged into the second chamber 12.

Wherein, the structure of the one-way liquid inlet valve and the one-way air inlet valve can be various. Taking the one-way liquid inlet valve as an example, the one-way liquid inlet valve may be a ball valve disposed in the liquid inlet 111, a groove body for the ball valve to move may be disposed above the liquid inlet 111, an opening of the groove body is disposed opposite to the liquid inlet 111, the groove body is disposed in the first cavity 11, and a through hole is disposed on an outer wall of the groove body. During specific work, in a first stroke, liquid in the liquid inlet channel 3 pushes the valve ball into the groove body from the liquid inlet 111, the liquid inlet 111 is opened, and the liquid enters the first cavity 11 from the through hole of the groove body through the liquid inlet 111; in the second stroke, due to the increase of the pressure in the first chamber 11, the valve ball continues to be blocked in the liquid inlet 111, so that the gas-liquid mixture in the first chamber 11 cannot be discharged into the liquid inlet channel 3, and the gas-liquid mixture in the first chamber 11 is ensured to be smoothly discharged into the second chamber 12. The specific one-way liquid inlet valve and the one-way air inlet valve can also refer to the structure of the existing one-way valve.

Fig. 3 is a cross-sectional view of the valve seat of the bottom valve of fig. 2. In particular implementation, as shown in fig. 3, the base valve seat 13 in the present embodiment may include: the base 131 and the cover 132 are oppositely arranged, the cover 132 is arranged close to the first chamber 11, and the cover 132 is fixed with the base 131; the base 131 is provided with an air inlet hole along the central axis direction for serving as the air inlet 112, and the liquid inlet 111 includes a plurality of liquid inlet holes provided on the base 131 and arranged around the air inlet hole. Wherein, one-way admission valve includes: an air valve core 14 and a first elastic member 15, wherein the air valve core 14 is installed in the air inlet 112 and the air valve core 14 is connected with the cover 132 through the first elastic member 15; one-way feed liquor valve includes: a liquid inlet valve plate 16 and a second elastic member 17, wherein the liquid inlet valve plate 16 is covered on the liquid inlet 111 and is connected with the cover body 132 through the second elastic member 17. Wherein the first elastic member 15 and the second elastic member 17 may be a spring or rubber.

During installation, a certain gap can be formed between the cover body 132 and the base body 131, and the gap is ensured to be located in the first cavity 11, during specific work, in a first stroke, the piston 2 moves upwards, the volume of the first cavity 11 is increased, the pressure is reduced, liquid located in the liquid inlet channel 3 flushes the liquid inlet valve plate 16, then the liquid enters the first cavity 11 from the gap between the cover body 132 and the base body 131, at the moment, the second elastic element 17 is in a compressed state, and similarly, gas located in the gas inlet channel 4 flushes the gas valve core 14, then the gas enters the first cavity 11 from the gap between the cover body 132 and the base body 131, and at the moment, the first elastic element 15 is in a compressed state; in the second stroke, the piston 2 moves downwards, the volume in the first chamber 11 decreases, the pressure increases, the liquid inlet valve plate 16 positioned on the liquid inlet 111 is continuously covered on the liquid inlet 111 under the elastic action of the second elastic piece 17 to block the liquid inlet 111, and meanwhile, the air valve core 14 positioned in the air inlet 112 is continuously installed in the air inlet 112 under the elastic action of the first elastic piece 15 to block the air inlet 112.

With reference to fig. 3, in order to further ensure that the liquid in the liquid inlet channel 1 and the gas in the gas inlet channel 2 do not leak during the process of entering the first chamber 11 through the bottom valve seat 13, in this embodiment, the cover 132 at least accommodates a portion of the seat 131, and the cover 132 is provided with a through hole 133.

Specifically, in the present embodiment, the cover 132 is completely covered on the top end of the seat 131, and at least a portion of the seat 131 is accommodated in the cover 132, so that the cover 132 and the seat 131 are connected more tightly. Meanwhile, the cover 132 is provided with a through hole 133 for passing liquid and gas, so that in the first stroke of the piston 2, after the liquid in the liquid inlet channel 1 and the gas in the gas inlet channel 2 respectively flush the liquid inlet valve plate 16, the liquid and the gas directly enter the first chamber 11 from the through hole in the cover 132, and the leakage of the liquid and the gas is effectively prevented.

Fig. 4 is a bottom view of the cover of fig. 3. Referring to fig. 4, the positions and the number of the through holes 133 on the cover 132 are not limited, for example, a plurality of through holes 133 may be disposed on the cover 132 above the air inlet holes, and a plurality of through holes 133 may be disposed on the cover 132 above the liquid inlet holes to ensure that the liquid and the gas can smoothly enter the first chamber 11 through the liquid inlet 111 and the air inlet 112. The through hole 133 may have various structures, such as a circular hole and a polygonal hole.

With continued reference to fig. 3, in the oil-gas production, the oil-gas medium contains solid particles with different diameters, so that the gas and the liquid obtained after the oil-gas passes through the gas-liquid separation device both contain solid particles, and in order to prevent the solid particles in the gas from depositing on the side wall of the top opening of the gas inlet hole to affect the sealing reliability of the valve plug 14, the axial cross section of the gas inlet hole of the present embodiment includes a tapered portion 1121, the gas valve plug 14 is installed in the tapered portion 1121, and the tapered portion 1121 is close to the first chamber 11.

Specifically, referring to fig. 3, in the present embodiment, an upper portion of the air inlet hole is provided as a tapered portion 1121, and the air valve plug 14 is installed at a large-diameter end of the tapered portion 1121, so that during the process that the air in the air inlet channel 4 enters the first chamber 11 from the air inlet hole, solid particles in the air can slide down from a small-diameter end of the tapered portion 1121 through an outer peripheral side wall of the tapered portion 1121, thereby preventing the situation that the sealing of the valve plug 14 fails due to the solid particles blocking the top end of the air inlet 112.

In addition, referring to fig. 3, since solid particles also exist in the liquid obtained after oil-gas separation, in order to avoid the influence of the solid particles in the liquid deposited at the top opening of the liquid inlet hole on the sealing performance of the liquid inlet valve plate 16, the exit direction of the liquid inlet hole of the embodiment is inclined from the central axis of the seat body 131, and the liquid is sprayed to the outside of the central axis, so that the solid particles in the liquid are shifted toward the outside of the central axis of the seat body 131 along with the spraying direction of the liquid, and finally fall off to the outside of the seat body 131, thereby preventing the influence of the solid particles on the sealing reliability of the liquid inlet valve plate 16.

With continued reference to fig. 2, in order to improve the stability of the base valve seat 13, the present embodiment may provide a liner seat ring 18 at the bottom of the first chamber 11, and fix the base valve seat 13 in the liner seat ring 18, so that the base valve seat 13 is stable at the bottom of the first chamber 11. During specific installation, one part of the cylinder sleeve seat ring 18 can be sleeved on the side wall of the bottom of the cylinder sleeve 1, and the other part of the cylinder sleeve seat ring is sleeved in a through hole formed in the top wall of the liquid inlet box, so that the sealing property between the first cavity 11 of the cylinder sleeve 1 and the liquid inlet box of the liquid inlet channel 3 is further improved.

Fig. 5 is a schematic view of the piston valve of fig. 2. Referring to fig. 5, the piston 2 in the present embodiment may include a piston valve base 21, a restoring member 22, and a piston valve plate 23; the piston valve base 21 is provided with a plurality of piston holes 211 around the axis of the piston valve base 21 for the gas-liquid mixture in the first chamber 11 to pass through, and the piston valve plate 23 covers one end of the piston hole 211 facing the second chamber 12 and is connected with the piston valve base 21 through the resetting piece 22; the outer side wall of the piston valve seat 21 is in sealing contact with the inner wall of the cylinder liner 1.

During specific work, in the second stroke of the piston 2, the piston 2 moves downwards, the volume of the first chamber 11 is reduced, the pressure intensity is increased, the volume of the second chamber 12 is increased, the pressure intensity is reduced, the gas in the first chamber 11 is firstly compressed by the piston valve base 21, then the gas enters the piston hole 211, and enters the second chamber 12 after the piston valve plate 23 is flushed, when the gas is completely discharged into the second chamber 12, the piston valve base 21 continues to move downwards, the liquid in the first chamber 11 is squeezed into the piston hole 211 and pushes the piston valve plate 23 open, and then enters the second chamber 12, the piston valve 21 continuously moves downwards until the bottom of the first chamber 11 is reached, and the gas and the liquid in the first chamber 11 are completely discharged into the second chamber 12; in the first stroke, the piston 2 moves upwards, the volume of the first chamber 11 increases, the pressure decreases, the volume of the second chamber 12 decreases, the pressure increases, the gas and the liquid in the first chamber 11 do not flush the piston valve plate 23, and the reset piece 22 moves the piston valve plate 23 to the top end of the piston hole 211 continuously by combining the pressure in the second chamber 12, the piston hole 211 is closed, the first chamber 11 and the second chamber 12 are completely separated, the gas and the liquid in the second chamber 12 are squeezed out of the second chamber 12, and meanwhile, the liquid in the liquid inlet channel 3 and the gas in the gas inlet channel 4 are sucked into the first chamber 11.

Wherein, the restoring member 22 can be a spring, and the spring can be directly fixed on the piston valve base 21. In the second stroke, the gas and the liquid in the first chamber 11 push the piston valve plate 23 open, at this time, the piston valve plate 23 drives the spring to bounce, and in the first stroke, the piston valve plate 23 has no upward impact force, and the spring drives the piston valve plate 23 to bounce back to the original position, and the piston valve plate 23 continues to cover the opening at the upper end of the piston hole 211. In addition, as shown in fig. 5, a piston valve cover body 24 may be fixed on the top end of the piston valve base 21, one end of a spring is fixed on the piston valve cover body 24, and the other end is connected to the piston valve plate 23, and in particular, when the piston valve plate 23 is impacted by the gas and liquid in the first chamber 11, the spring is compressed, and the gas and liquid enter the second chamber 12 from the top end opening of the piston hole 211; when the piston valve plate 23 has no upward impact force, the spring is reset and drives the piston valve plate 23 to continuously cover the piston hole 211.

Similar to the exit direction of the liquid inlet hole, the exit direction of the piston hole 211 is inclined from the central axis of the piston valve base 21, and both the liquid and the gas are ejected to the outside of the central axis, so that the solid particles carried in the liquid and the gas directly fall to the side of the piston valve base 21, and the solid particles are prevented from depositing at the top opening of the piston hole 211 to affect the sealing reliability of the piston valve plate 23.

In order to improve the sealing performance between the outer side wall of the piston valve base 21 and the inner wall of the cylinder liner 1, a sealing ring 25 may be sleeved between the outer side wall of the piston valve base 21 and the inner wall of the cylinder liner 1 in the present embodiment.

In order to clean the solid particles remained on the inner wall of the cylinder liner 1 by the oil-gas mixture, the present embodiment may be formed with a saw-tooth structure on the outer side surface of the seal ring 25. The sealing ring 25 moves up and down under the driving of the piston valve base 21, and the sawtooth structure on the sealing ring 25 continuously rubs with the inner wall of the cylinder sleeve 1, so that solid particles are separated from the inner wall of the cylinder sleeve 1 and are discharged along with the oil-gas mixture. This embodiment clears up the inner wall of cylinder liner 1 through sawtooth structure for the inner wall of cylinder liner 1 is more smooth, the effectual motion efficiency that improves piston valve base 21, and then has improved this piston plunger composite pump's work efficiency, and the setting up of this sawtooth structure makes the clearance of the inner wall of cylinder liner 1 convenient and fast more. The sealing ring 25 can be made of polyurethane material, and has the advantages of good elasticity, wear resistance and long service life.

Wherein, the partly sawtooth of this sawtooth structure inclines towards second chamber 12, the rest sawtooth of sawtooth structure inclines towards first chamber 11, when making piston valve base 21 rebound, the partly sawtooth of slope towards second chamber 12 and the solid particle relative motion on the cylinder liner 1 inner wall, then the sawtooth of this part can effectively be clear away the solid particle, and when piston valve base 21 rebound, the relative motion of the rest sawtooth of slope towards first chamber 11 and the solid particle on the cylinder liner 1 inner wall, then this rest sawtooth can effectively be clear away the solid particle, the cleaning effect of this sawtooth structure to the inner wall of cylinder liner 1 has further been improved.

Referring to fig. 1 and 2, the piston-plunger compound pump of the embodiment may further include a liquid discharge channel 5, an outlet end of the liquid discharge channel 5 is used for communicating with an oil-gas conveying pipeline, an oil discharge port 121 is provided on the second chamber 12 for communicating with an inlet end of the liquid discharge channel 5, and the piston 2 is further used for discharging the gas-liquid mixture in the second chamber 12 into the liquid discharge channel 5 in a first stroke, and then discharging the gas-liquid mixture into the oil-gas conveying pipeline for conveying. As shown in fig. 1, a cooling cavity 7 may be further provided at the outer periphery of the cylinder liner 1, and a cooling medium for cooling the air-fuel mixture in the cylinder liner 1 is provided in the cooling cavity 7.

Wherein, a one-way drain valve is arranged on the oil outlet 121, so that the oil-gas mixture in the second chamber 12 can only be discharged into the drain passage 5, and the oil-gas mixture in the drain passage 5 cannot be discharged into the second chamber 12. The structure of the one-way liquid discharge valve can refer to the structure of the one-way liquid inlet valve or the one-way air inlet valve, or the existing one-way valve can be directly adopted, and the description is omitted here.

For example, as shown in fig. 2, in some examples, the drainage channel 5 may include a drainage tank 51 disposed above the cylinder liner 1 and a drainage trap 52 disposed on the drainage tank 51, and the drainage trap 52 may be detachably disposed at an outlet end of the drainage tank 51 to facilitate replacement of the drainage trap 52.

In order to further improve the working efficiency of the piston-plunger compound pump of the present embodiment, the piston-plunger compound pump may include a plurality of cylinder liners 1 and a piston 2 disposed in each cylinder liner 1, and each piston 2 is operated once in one time period.

The initial positions of the pistons 2 are different, that is, the working phases of the pistons 2 in the cylinder liners 1 are different. Taking four cylinder sleeves 1 as an example, the working phases of the pistons 2 in the cavities can differ by 90 degrees, so that the impact force of the whole equipment in the operation process of the piston-plunger compound pump is effectively reduced, and the discharge of high-pressure media is more stable.

Fig. 6 is a left side view of fig. 1. As shown in fig. 6, the inlet elbow 42 of each inlet passage 4 may be commonly connected to a gas distributor 43, and one end of the gas distributor 43 is communicated with a gas outlet of the gas-liquid separation device. The flow control of each intake pipe can be realized by operating the gas distributor 43, and the working efficiency is further improved.

Referring to fig. 1 and 6, the piston-plunger compound pump of the present embodiment further includes a driving member and a transmission member 6, wherein the transmission member 6 includes a crank assembly eccentrically connected to the transmission shaft, the crank assembly includes two cranks 61 disposed at an interval, a link mechanism 62 is eccentrically fixed between the two cranks 61, the link mechanism 62 is connected to a force-bearing frame 63, and the piston rod 26 of the piston 2 passes through the through holes of the bottom wall and the top wall of the liquid discharge tank 51 and is fixed on the force-bearing frame 63. In operation, the transmission shaft drives the crank 61 to rotate, so that the link mechanism 62 drives the stressed frame 63 to move up and down, and further drives the piston 2 to move up and down.

Fig. 7 is a schematic structural view of the link mechanism in fig. 1. Referring to fig. 7, in the actual assembly process, errors caused by manufacturing and installation may cause the bottom plate of the force-bearing frame 63 and the piston rod 26 to be not perpendicular, so that the sealing member disposed between the inner walls of the through holes formed in the top wall and the bottom wall of the liquid discharge box 51 may be worn. In order to prevent the above situation, the spherical conical surface gaskets 631 may be respectively fixed on the upper and lower sides of the bottom plate of the force-bearing frame 63, so as to avoid the situation that the piston rod 26 generates a lateral force due to the non-perpendicularity between the piston rod 26 and the bottom plate of the force-bearing frame 63, thereby effectively reducing the friction force of the piston rod 26 on the sealing member and prolonging the service life of the sealing member. As shown in fig. 6, a seal box 511 is provided in a through hole formed in a top wall of the drain tank 51, so that the sealing property between the piston rod 26 and the through hole is improved, and the leakage of the medium in the drain tank 51 is effectively prevented. Meanwhile, to prevent the piston rod 26 from being deflected left and right, a centering sleeve 512 is provided between a part of the sidewall of the piston rod 26 and the inner wall of the sealed case 511.

As shown in fig. 7, the link mechanism 62 includes a link 621, and an upper link pin 622 and a lower link pin 623 connected to two ends of the link 621 through bearings, wherein the link 621 is disposed perpendicular to the transmission shaft, two ends of the upper link pin 622 are eccentrically fixed to the crank 61, and two ends of the lower link pin 622 are fixed to the force-bearing frame 63. During operation, the transmission shaft drives the crank 61 to eccentrically rotate, so as to drive the upper connecting rod pin 622 to rotate, the connecting rod 621 moves up and down while swinging around the lower connecting rod pin 623 under the driving of the upper connecting rod pin 622, so that the stress frame 63 moves up and down, and the piston rod 26 reciprocates under the action of the stress frame 63. Referring to fig. 1, in order to improve the efficiency of the lower link pin 623 moving the force-bearing frame 6, in this embodiment, radial ball bearings 624 are installed at two ends of the lower link pin 623, a guide rail 625 is vertically fixed on the top wall of the liquid discharge box 51, and the lower link pin 623 rolls up and down in the guide rail 625 through the radial ball bearings 624.

Fig. 8 is a top view of fig. 1. Referring to fig. 1, 6 and 8, in order to improve the stability of the guide rail 625, the top end of the guide rail 625 may be fixed to the bearing housing bracket 69. Meanwhile, in order to ensure the stability of the bearing bracket 69, reinforcing brackets 8 may be fixed to front and rear sides of the bearing bracket 69, respectively, and the bottom ends of the reinforcing brackets 8 are fixed to the top wall of the drain tank 51. When the piston-plunger compound pump includes a plurality of pistons 2, the reinforcing bracket 8 may include a plurality, and the reinforcing bracket 8 is provided on each bearing housing bracket 69. For further stabilizing a plurality of reinforcing brackets 8, the reinforcing brackets 8 on the same side can be fixed on the connecting shafts 9, and the connecting plates 10 are respectively arranged at the two ends of the two connecting shafts 9, so that the two connecting shafts 9 are fixed between the two connecting plates 10, and the stability of the connecting shafts 8 is further ensured.

With continued reference to fig. 1, a drive shaft is illustrated with 4 pistons 2 in the piston-plunger compound pump as an example, and may include a coupling 64, a power input shaft 65, 3 intermediate power transmission shafts 66, and a disc axle 67, which are sequentially spaced in a horizontal direction. The power input shaft 65, the 3 intermediate force transmission shafts 66 and the disk axle 67 are all mounted on a bearing seat 68, and the bearing seat 68 is fixed on a bearing seat bracket 69. Specifically, one end of the coupling 64 is connected with the driving member, the other end of the coupling 64 is connected with the power input shaft 65, one end of the power input shaft 65, two ends of each middle force transmission shaft 66 and one end of the disc axle 67 facing the middle force transmission shaft 66 are respectively provided with a crank 61 in an eccentric mode, and two ends of the upper connecting rod pin 622 are respectively fixed on the two opposite cranks 61 in an eccentric mode.

The transmission shaft has the following specific force transmission process: the force transmission between the coupler 64 and the power input shaft 65 can be realized through a transmission torque key, and the force transmission between the power input shaft 65 and the first middle force transmission shaft 66, between two adjacent middle force transmission shafts 66 and between the third middle force transmission shaft 66 and the turning shaft 67 is realized through the upper connecting rod pins 622. The drive shaft rotates each crank 61, so that each upper link pin 622 moves the link 621 up and down while swinging around the lower link pin 623, thereby driving the piston 2 to reciprocate. Wherein, can overlap on above-mentioned transmission shaft and establish the protection casing to make the transmission shaft keep apart with external environment, and then improve the life of this transmission shaft and play the safety protection effect. The top ends of the reinforcing brackets 8 may be fixed to the bearing seat 68, so as to further prevent the bearing seat 68 from shifting.

The present embodiment provides a piston-plunger combination pump, including: a cylinder liner; the piston is arranged in the cylinder sleeve and is used for dividing the cylinder sleeve into a first cavity and a second cavity; the inlet ends of the liquid inlet channel and the gas inlet channel are communicated with a gas-liquid separation device; the first cavity is provided with a liquid inlet communicated with the outlet end of the liquid inlet channel and a gas inlet communicated with the outlet end of the gas inlet channel at intervals; the piston is used for sucking liquid in the liquid inlet channel and gas in the gas inlet channel into the first chamber in a first stroke, and the pressure of the liquid inlet channel is higher than that of the gas inlet channel; and a second chamber for discharging the gas-liquid mixture sucked into the first chamber into the second chamber in a second stroke. The utility model is provided with the liquid inlet channel and the air inlet channel which are communicated with the first cavity of the cylinder sleeve, the inlet ends of the liquid inlet channel and the air inlet channel are respectively communicated with the gas-liquid separation device, the outlet ends of the liquid inlet channel and the air inlet channel are correspondingly communicated with the liquid inlet and the air inlet which are arranged on the first cavity at intervals, make liquid and gas in the oil gas respectively through inlet channel and inlet channel separately independently get into first cavity in, compare in current piston plunger combination pump only through single passageway suction fluid mixture and very easily lead to the condition of air lock and take place, the utility model discloses the accessible is adjusted inlet pressure or inlet pressure and is made the inlet pressure be higher than inlet pressure, guarantees in liquid and the gas gets into first cavity simultaneously, and the effectual gas lock phenomenon of taking place because of the gas is lighter in the first cavity of preferential entering of having prevented for liquid and the gaseous homoenergetic in the oil gas obtain effectual pressure boost.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims (10)

1. A piston-plunger combination pump, comprising:

a cylinder liner;

the piston is arranged in the cylinder sleeve and is used for dividing the cylinder sleeve into a first cavity and a second cavity;

the inlet ends of the liquid inlet channel and the gas inlet channel are communicated with a gas-liquid separation device; liquid inlets communicated with outlet ends of the liquid inlet channels and air inlets communicated with outlet ends of the air inlet channels are arranged in the first cavity at intervals;

the piston is used for sucking liquid in the liquid inlet channel and gas in the gas inlet channel into the first chamber in a first stroke, and the liquid inlet pressure of the liquid inlet channel is higher than the gas inlet pressure of the gas inlet channel; and a second chamber for discharging the gas-liquid mixture sucked into the first chamber into the second chamber in a second stroke.

2. The piston-plunger compound pump as claimed in claim 1, wherein the liquid inlet channel is sleeved outside the air inlet channel, and the liquid inlet is arranged around the air inlet.

3. The piston-plunger compound pump as claimed in claim 2, wherein the first chamber is provided with a base valve seat, and the gas inlet and the liquid inlet are both provided on the base valve seat;

the air inlet is provided with a one-way air inlet valve, and the liquid inlet is provided with a one-way liquid inlet valve.

4. The piston-plunger compound pump of claim 3, wherein the base valve seat comprises: the cover body is arranged close to the first cavity and fixed with the base body; the base body is provided with an air inlet used as the air inlet along the central axis direction, the liquid inlet comprises a plurality of liquid inlet holes arranged on the base body, and the liquid inlet holes are arranged around the air inlet;

the one-way intake valve includes: the air valve core is arranged in the air inlet and is connected with the cover body through the first elastic piece; the one-way liquid inlet valve comprises: the liquid inlet valve plate is covered on the liquid inlet and is connected with the cover body through the second elastic piece.

5. The piston-plunger combination pump as defined in claim 4, wherein the cover accommodates at least a portion of the base body, and the cover has a through hole.

6. The piston-plunger combination pump of claim 4, wherein the axial cross-section of the intake bore includes a tapered portion, the air valve spool being mounted within the tapered portion, and the tapered portion being adjacent to the first chamber.

7. The piston-plunger compound pump as claimed in any one of claims 4 to 6, wherein the exit direction of the liquid inlet hole is inclined from the central axis of the housing, and the liquid is ejected to the outside of the central axis.

8. The piston-plunger compound pump of any one of claims 1-6, wherein the piston comprises a piston valve seat, a reset member, and a piston valve plate;

the piston valve base is provided with a plurality of piston holes around the axis of the piston valve base, the piston holes are used for the gas-liquid mixture in the first chamber to pass through, and the piston valve plate cover is arranged at one end of the piston hole facing the second chamber and is connected with the piston valve base through the resetting piece;

the outer side wall of the piston valve base is in sealing contact with the inner wall of the cylinder sleeve.

9. The piston-plunger compound pump as claimed in claim 8, wherein a sealing ring is sleeved between the outer side wall of the piston valve base and the inner wall of the cylinder sleeve;

the outer side surface of the sealing ring is provided with a sawtooth structure, a part of sawteeth of the sawtooth structure incline towards the second chamber, and the rest of sawteeth of the sawtooth structure incline towards the first chamber.

10. The piston-plunger compound pump of any one of claims 1-6, wherein the piston-plunger compound pump comprises a plurality of cylinder liners and a piston disposed within each cylinder liner;

the initial position of each piston is different and each piston operates once in a time period.

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