CN206694243U - A kind of CP types single-screw (single screw) pump - Google Patents

Abstract

The utility model discloses a CP type single-screw pump, which is suitable for single-phase liquid transportation or gas-liquid two-phase mixed transportation, especially when the pump is rotating forward and mixed with gas-liquid two-phase flow, it can automatically realize the gas phase medium. internal compression. It is characterized in that: at the rear of the screw, a first through hole is opened between the area where the depth of the screw groove is close to 0 and the end surface of the rear of the screw, and a valve assembly for controlling fluid suction or discharge is installed in the first through hole. Corresponding to each screw groove, a through hole with the same position and shape as the first through hole is opened, and a valve assembly identical to the valve assembly is installed inside each through hole. The utility model proposes a key technology for developing the CP type single-screw machine into the field of pumps. The utility model CP single screw pump has the advantages of simple structure, high head, high efficiency, strong self-priming ability, etc., and can be used in urban water supply, irrigation, oil and gas mixed transportation and other fields.

Description

A CP type single screw pump

Technical field:

The utility model relates to a pump, in particular to a CP type single screw pump.

Background technique:

The screw pump is a rotary pump that relies on the volume change and movement of the meshing space formed by the pump body and the screw to transport or pressurize the fluid medium. The screw pump has the characteristics of small size, high efficiency and high lift, and has self-priming function. It is a constant flow pump, and the flow rate is proportional to the speed. Screw pumps include single screw pumps, twin screw pumps, triple screw pumps, etc. A single screw pump usually refers to a positive displacement pump in which a single screw rotates in an internal thread groove of the pump body to drive a fluid medium. In the existing literature (patent number: WO82/03428), the CP single-screw machine widely used in the field of compressors is applied to the field of pumps, and a CP-type single-screw pump is proposed. Conveying fluid media. In the existing literature (patent number: CN 203560094 U), the most commonly used single-screw double-star wheel structure in single-screw compressors is applied to the field of pumps. However, neither of the above two patents involves the key issue of developing the CP-type single-screw machine into the field of pumps, that is, how the working chamber sucks and discharges the fluid. When rotating forward, if the triangular orifice on the CP single-screw compressor is still used as the discharge orifice of the CP single-screw pump, when the screw groove is closed, there is still a long section between the working chamber and the orifice in the circumferential direction of the cylinder. Due to the incompressibility of the liquid, the liquid trapped in the working chamber cannot be discharged, and the phenomenon of trapped liquid will occur, and the function of conveying the fluid medium cannot be realized. When reversing, if the triangular orifice on the CP single-screw compressor is still used as the suction orifice of the CP single-screw pump, when the screw groove turns over the triangular orifice, no fluid medium will enter the working chamber. However, the moving direction of the star gear teeth further increases the working chamber, and because the liquid cannot expand, the phenomenon of trapped liquid will also occur, and the function of conveying the fluid medium cannot be realized. (Note: It is stipulated that the star gear teeth are engaged by the front part of the screw, and the rear part is engaged, and the direction that makes the volume of the working chamber decrease is the forward rotation direction of the pump; it is stipulated that the star gear teeth are engaged by the rear part of the screw rod, and the front part is engaged by the screw. , and the direction in which the volume of the working chamber increases is the reverse direction of the pump.)

Utility model content:

The purpose of this utility model is to propose a theoretically feasible CP-type single-screw pump for the shortcomings of the above-mentioned background technology. .

In order to achieve the above object, the utility model adopts the following technical solutions to realize:

A CP-type single-screw pump, including a casing, a cylindrical screw arranged in the casing, and two planar star wheels, the screw is divided into two parts based on the center line of the two star wheels;

In the first part, the screw groove has a complete length L ₁ along the axial direction of the screw, and the depth of the screw groove changes from the maximum value to 0. This part is defined as the rear part of the screw, and the screw sealing section is connected to the rear part of the screw on the screw; The second part, the length of the screw groove along the axial direction of the screw is L ₂ , and L ₂ <L ₁ , the depth of the screw groove changes from the maximum value to h ₁ , h ₁ >0, this part is defined as the front part of the screw; corresponding to the screw , the casing is divided into the rear part and the front part. At the rear part of the screw, a first through hole is opened between the area where the depth of the screw groove is close to 0 and the end face of the rear part of the screw rod. A control fluid suction or valve assembly for the discharge process;

Corresponding to each screw groove, a through hole with the same position and shape as the first through hole is provided, and the same valve assembly as the valve assembly 7 is installed inside each through hole, and the first through hole is connected with the first chamber. Connected, the first chamber is surrounded by the rear end face of the screw, the rear end cover of the casing and the inner wall surface of the rear part of the casing; the first suction/discharge hole is set radially on the casing at the rear of the casing, and the second The second chamber is surrounded by the front end surface of the screw, the front end cover of the casing and the inner wall surface of the front part of the casing, and is connected with the star wheel cavity, and the second suction/discharging hole is set radially in the front of the casing .

A further improvement of the utility model is that the first through hole is a stepped hole, including a first round hole and a second round hole connected together, and the aperture of the first round hole is smaller than the aperture of the second round hole, and the diameter of the first round hole is smaller than that of the second round hole. The center line does not coincide with the center line of the second circular hole, and the second circular hole is provided with an internal thread.

The further improvement of the utility model is that point A is set as the point on the section of the screw rod, and the depth of the screw groove is 0, and point B is the point on the orifice of the first round hole close to the screw groove, which is the closest point to point A, and point A and B The distance between points in the radial direction of the screw is d, let d _min be the minimum value of d to ensure that the wall of the first round hole has sufficient rigidity and strength, and the minimum distance d between point A and point B in the radial direction of the screw is d _min .

The further improvement of the utility model is that point P is set as the end point of the screw groove, and point C is the point closest to point P on the orifice of the first round hole close to the screw groove, when the distance between point A and point B is determined Next, the position of the first round hole is close to the bottom curve PD of the screw groove on the rear side of the star gear teeth to ensure the minimum distance between point C and point P.

The further improvement of the utility model is that when the valve assembly is a cone valve or a ball valve, the valve assembly includes a valve plate, a spring, a lift limiter, a spherical or conical valve core; The cylindrical surface of the valve plate is provided with external threads and matched with the internal threads of the second round hole; along the direction parallel to the center line of the valve plate, a second through hole is opened on the valve plate, and the second through hole It is an eccentric hole, and the lift limiter is a cylinder with an external thread at the tail. The lift limiter, spring and spherical or conical spool are connected in sequence, and the spherical or conical spool is used to block the first round hole or second via.

The further improvement of the utility model is that when the valve assembly is a strip valve, the valve assembly is composed of a valve plate, a valve plate and a lift limiter; A second through hole is opened on the valve plate in the direction of Block the second through hole.

The further improvement of the utility model is that there is a unilateral gap of 0.01-0.10 mm between the sealing section of the screw rod and the inner hole of the casing.

The further improvement of the utility model is that a return pipe is provided between the first chamber of the pump and the second chamber of the pump, and a return valve is provided on the return pipe.

The utility model has the following beneficial effects:

The utility model proposes a key technology for developing the CP type single-screw machine into the field of pumps. The utility model CP single screw pump has the following advantages:

1. The structure is simple, and there is no need to set a specific shape of the discharge hole on the cylinder and complex discharge channels after casting the discharge hole, which greatly reduces the difficulty of manufacturing the casing.

2. It can transport both single-phase liquid medium and mixed gas-liquid two-phase medium. The volumetric gas content of the transported fluid medium is allowed to vary within a wide range, from 0 to close to 100%. (When the gas fraction reaches 100%, because there is no liquid cooling, it can only work in a short period of time, and once the exhaust temperature exceeds the limit value, it should be shut down).

3. When the pump is running forward, the advantage is that when the gas-liquid two-phase medium is mixed, due to the setting of the spring automatic discharge valve, the internal compression of the gas-phase medium can be automatically realized. No matter how the suction, discharge pressure and gas content change, the gaseous phase medium can be raised from the suction pressure to the discharge pressure in the way of internal compression, which is more energy-saving than the process of boosting the pressure without internal compression in the gaseous phase, which will enable the pump to operate in a wider working range. Maintain high efficiency within the scope of the environment.

4. When the pump reverses, due to the relative movement of the star wheel and the screw, the volume of the working chamber expands rapidly from 0 to the maximum, so it has a strong and fast self-priming ability, and there is no need to prime the pump before starting.

5. The pulsation of instantaneous flow is small. Taking the 6-groove screw as an example, each screw groove discharges twice in one revolution, and the screw discharges 12 times in one revolution, which greatly reduces the pulsation of instantaneous flow.

6. The structure of the CP-type single-screw pump can also be used for a CP-type single-screw compressor.

Description of drawings:

Figure 1: Schematic diagram of the three-dimensional structure of the CP single screw pump;

Figure 2: Schematic diagram of the planar structure of the CP single screw pump;

Figure 3: Structural diagram of the through hole opened on the screw;

Figure 4: Schematic diagram of the opening position of the through hole on the screw groove;

Figure 5: The structure of the cone valve (ball valve) and its installation method when the pump is running forward;

Figure 6: The structure of the cone valve (ball valve) and its installation when the pump is reversed;

Figure 7: The structure of the bar valve and its installation when the pump is running forward;

Figure 8: Structure of the strip valve and how it fits when the pump is reversed.

In the figure: 1-screw, 2-star wheel, 3-casing, 4-screw groove, 5-screw sealing section, 6-first through hole, 7-valve assembly, 8-first chamber, 9-machine Shell rear end cover, 10-first suction/discharging hole, 11-second chamber, 12-housing front end cover, 13-star wheel chamber, 14-communication hole, 15-first round hole, 16 -Second round hole, 17-valve plate, 18-spring, 19-lift limiter, 20-spool, 21-second suction/discharge hole, 22-valve plate, 23-lift limiter, 24- screw.

detailed description:

Below in conjunction with accompanying drawing, the utility model is further described.

As shown in Figures 1 to 8, a CP-type single-screw pump provided by the utility model includes a casing 3 and a cylindrical (C-type) screw 1 arranged in the casing 3 and two planar (P-type) screw pumps. ) star wheel 2, based on the center line of the two star wheels 2, the screw 1 is divided into two parts; in the first part, the screw groove 4 has a complete length L ₁ along the axial direction of the screw rod 1, and the depth of the screw groove 4 From the maximum value to 0, this part is defined as the rear of the screw, and the screw sealing section 5 is connected to the rear of the screw on the screw 1; in the second part, the length of the screw groove 4 along the axial direction of the screw 1 is L ₂ , and L ₂ <L ₁ , the depth of the screw groove 4 changes from the maximum value to h ₁ , h ₁ >0, this part is defined as the front part of the screw; corresponding to the screw 1, the casing 3 is divided into the rear part and the front part. At the rear of the screw 1, a first through hole 6 is provided between the area where the depth of the screw groove is close to 0 and the end surface of the rear of the screw, and a valve assembly 7 for controlling the suction or discharge process of the fluid is installed in the first through hole 6; corresponding to each A screw groove is provided with the same through hole as the first through hole 6 in position and shape, and the same valve assembly as the valve assembly 7 is installed inside each through hole, the first through hole 6 and the first chamber 8 Connected, the first chamber 8 is surrounded by the end face of the rear part of the screw, the end cover 9 of the rear part of the casing and the inner wall surface of the rear part of the casing 3; The row of holes 10 and the second chamber 11 are surrounded by the front end surface of the screw rod 1, the front end cover 12 of the casing and the inner wall surface of the front of the casing 3, and communicate with the star wheel chamber 13. The second suction/discharge hole 14 is opened in the radial direction. When working, the CP single-screw pump can deliver and pressurize the fluid medium regardless of forward rotation or reverse rotation.

The first through hole 6 is a stepped hole, including a connected first circular hole 15 and a second circular hole 16, and the aperture of the first circular hole 15 is smaller than the aperture of the second circular hole 16, and the diameter of the first circular hole 15 The center line does not coincide with the center line of the second round hole 16, and the second round hole 16 is provided with an internal thread.

As shown in Figure 3, point A is the point on the screw profile where the depth of the screw groove is 0. Point B is the closest point to point A on the aperture of the first circular hole 15 close to the screw groove. The distance between point A and point B in the radial direction of the screw is d. d _min is the minimum value of d to ensure that the wall of the first circular hole 15 has sufficient rigidity and strength. It is characterized in that: the distance between point A and point B in the radial direction of the screw rod is d≥d _min .

As shown in Figure 4, point P is the end point of the screw groove. Point C is the point closest to point P on the orifice of the first circular hole 15 close to the screw groove. When the distance between point A and point B is determined, the position of the first circular hole 15 is close to the bottom curve PD of the screw groove on the rear side of the star gear teeth to ensure that the distance between point C and point P is as small as possible. This is because: when the pump rotates forward, the distance between point C and point P is smaller, and when the star wheel rotates through the first circular hole 15, the fluid enclosed in the working chamber that cannot be discharged through the first circular hole 15 is less. This part of the fluid can be discharged from the working chamber through the gap between the screw and the star wheel. When the pump is reversed, the distance between point C and point P is smaller, and when the star wheel turns from point P to point C, the process of working chamber to overcome the back pressure and increase the volume is shorter and more energy-saving.

The working cavity of the pump is surrounded by the inner wall of the casing 3, the working surface of the star gear teeth 22, the front and rear side walls of the screw groove 4 and the bottom surface of the groove.

As shown in FIG. 5 and FIG. 6 , when the installed valve assembly 7 is a cone valve or a ball valve, the valve assembly includes a valve plate 17 , a spring 18 , a lift limiter 19 , and a ball or cone valve core 20 . The valve plate 17 is a cylinder with the same diameter as the large hole. The cylindrical surface of the valve plate 17 is provided with an external thread and matches with the internal thread of the second circular hole 16 . A second through hole 21 is opened on the valve plate 17 along a direction parallel to the center line of the valve plate, and the through hole is an eccentric hole. The lift limiter is a cylinder with an external thread at the tail. The lift limiter 19 , the spring 18 and the spherical or conical spool 20 are connected in sequence, and the spherical or conical spool 20 is used to block the first circular hole 15 or the second through hole 21 .

When the pump needs to rotate forward, referring to FIG. 5 , the lift limiter 19 of the valve assembly 7 is connected to the valve plate 17 through threads. The axes of the lift limiter 19, the spring 18, and the spool 20 coincide with the axis of the first round hole 15 of the stepped hole. The spool 20 seals the opening of the first round hole 15 near the end of the second round hole 16 under the action of spring force. The valve assembly 7 functions as a discharge valve.

When the reverse rotation of the pump is required, referring to FIG. 6 , the lift limiter 19 of the valve assembly 7 is connected to the screw body behind the interface of the first through hole 6 through threads. The axes of the lift limiter 19 , the spring 18 , and the valve core 20 coincide with the axis of the second through hole 21 on the valve plate 17 . The valve core 20 seals the opening of the second through hole 21 on the valve plate 17 under the action of spring force. The valve assembly acts as a check valve.

Referring to FIG. 7 and FIG. 8 , when the installed valve assembly 7 is a strip valve, the valve assembly is composed of a valve plate 17 , a valve plate 22 and a lift limiter 23 . The valve sheet 22 is a strip-shaped metal sheet with elasticity. The lift limiter 23 is a metal sheet with high rigidity. The lift limiter 23 and the root of the valve plate 22 are fastened on the valve plate 17 by screws 24 , and the strip valve plate 22 is used to block the second through hole 21 .

When the pump needs to rotate forward, referring to FIG. 7 , the valve assembly 7 is screwed into the large hole and fastened by threads. The valve plate 22 and the lift limiter 23 are located on the side close to the first chamber 8 . The valve assembly 7 acts as a discharge valve.

When the pump needs to be reversed, referring to FIG. 8 , the valve assembly 7 is screwed into the large hole and tightened by threads. The valve plate 22 and the lift limiter 23 are located on the side close to the screw groove 4 . The valve assembly 7 acts as a non-return valve.

A unilateral gap of 0.01-0.10 mm is left between the screw sealing section 5 and the inner hole of the casing to form a gap seal to prevent the fluid in the first chamber 8 from leaking to the second chamber 11 or vice versa.

A return line is arranged between the first chamber 8 of the pump and the second chamber 11 of the pump. A return valve is arranged on the return pipe. Its function is: when the pump is started, the return valve is opened to ensure that the prime mover is not overloaded. When the pump is working, the flow of the pump can be adjusted by adjusting the opening of the return valve.

The structure of the CP-type single-screw pump can also be used for a CP-type single-screw compressor.

Embodiment 1: The pump rotates forward and the installed valve assembly is a ball valve or a cone valve. Referring to FIG. 5 , the valve plate 17 is provided with a second through hole 21 , which is an eccentric hole. The lift limiter 19 of the valve assembly 7 is connected with the valve plate 17 through the thread at its tail. The spring 18 root is welded on the valve plate 17, and the valve core (ball or cone) 20 is welded on the spring 18 top. The center lines of lift limiter 19, spring 18 and spool 20 should coincide. It is required that the eccentricity of the centerline of the lift limiter 19 to the centerline of the valve plate 17 is the same as the eccentricity of the centerline of the first round hole 15 to the centerline of the second round hole 16 . The valve plate 17 on which the valve assembly is installed is screwed into the second circular hole 16, and the centerline of the lift limiter 19 is required to coincide with the centerline of the first circular hole 15, and the valve plate 17 is locked. The stiffness of the spring 18 used should not only ensure that the opening pressure δP of the spool 20 is not too large to avoid additional energy loss, but also ensure that the spool 20 can be quickly attached to the hole of the first circular hole 15 after the discharge process of the working chamber is completed. mouth.

The transported fluid is sucked into the second chamber 11 of the pump through the second suction/discharge hole 14, at this time the hole 14 is the suction orifice, and the second chamber 11 is the suction chamber. The fluid in the suction chamber enters and fills the screw groove 4 through the opening on the inverted cone on the front end face of the screw 1 through both radial and axial directions. As the screw 1 drives the star wheel 2 to further rotate, the star wheel teeth will close the screw groove 4, at this time the volume of the working chamber reaches the maximum, and the fluid suction process is completed. As the screw 1 continues to rotate, the volume of the working chamber will decrease. When the conveyed fluid medium is a single-phase liquid medium, the liquid pressure rises rapidly. When the conveyed fluid medium is two-phase flow or multiphase flow containing gas phase, as the volume of the working chamber decreases, the law of boosting pressure of the gas phase medium is as follows (considered by ideal gas):

PV ⁿ = const (1)

In the formula, P—the pressure of the gas in the working chamber; V—the volume of the gas in the working chamber; n——the index of the compression process. When gas and liquid are mixed, the pressure of the liquid rises synchronously with the gas. Due to the setting of the automatic discharge valve, the internal compression of the gaseous medium can be realized automatically. No matter how the suction, discharge pressure and gas content change, the gaseous phase medium can be raised from the suction pressure to the discharge pressure in the way of internal compression, which is more labor-saving than the boosting process of the gaseous phase without internal compression, which will make the pump work in a wider range Maintain high efficiency within the range of working conditions.

When the pressure of the fluid in the working chamber is greater than the sum P ₂ +δP of the internal pressure P ₂ of the first chamber 8 and the opening pressure δP of the discharge valve, the valve core is pushed open. The fluid in the working chamber is discharged to the first chamber 8 through the first circular hole 15 , the valve gap, the second circular hole 16 and the second through hole 21 on the valve plate. The first chamber 8 is a discharge chamber. This discharge process continues until the star gear teeth reach the first circular hole 15. At this time, the high-pressure fluid in the first through hole 6 communicates with the low-pressure fluid filled into the screw groove again through the non-pressure bearing surface of the star gear teeth, and the pressure drop When the pressure of the suction chamber is reached, the spool 20 re-closes the first circular hole 15 under the action of the spring force and the pressure difference on both sides. After the discharge process is completed, a small amount of fluid remaining in the working chamber is unloaded through the gap between the star wheel 2 and the screw 1 until the star wheel teeth break away from the screw groove. Due to the gap seal formed between the sealing section 5 of the screw and the inner wall of the cylinder, only a small amount of the fluid medium in the discharge chamber 8 flows back to the low-pressure side through the sealing section 5, and most of the fluid medium is discharged radially through the first suction/discharge hole 10 . Complete the delivery and pressurization of the fluid medium.

Embodiment 2: The pump is reversed, and the installed valve assembly is a ball valve or a cone valve. Referring to Fig. 6, the valve plate 17 is provided with a second through hole 21, which is an eccentric hole. The lift limiter of the valve assembly 7 is physically connected with the screw behind the interface with the stepped first through hole 6 through the screw thread at the tail. The root of the spring 18 is welded on the interface of the stepped first through hole 6 , and the valve core 20 (ball or cone) is welded on the top of the spring 18 . The center lines of lift limiter 19, spring 18 and spool 20 should coincide. It is required that the eccentricity of the centerline of the lift limiter 19 to the centerline of the second circular hole 16 is the same as the eccentricity of the centerline of the second through hole 21 on the valve plate 17 to the centerline of the valve plate 17 . When the valve plate 17 is screwed into the first circular hole 15, the center line of the lift limiter 19 is required to coincide with the center line of the second through hole 21 on the valve plate 17, and the valve plate 17 is locked. When the star gear teeth slide from point P to point C, a certain degree of vacuum is formed because they are not connected to the second circular hole 16 . The stiffness of the spring 18 used should ensure that the spool 20 can be opened under the condition of this degree of vacuum or slightly greater than this degree of vacuum.

The conveyed fluid is sucked into the first chamber 8 of the pump through the first suction/discharge hole 10, and the first chamber 8 is a suction chamber. As the screw 1 drives the star wheel 2 to further rotate, the star wheel teeth will engage into the screw groove 4 from the point P at the end of the screw groove 4 (the depth of the screw groove is 0), and the volume of the working chamber is 0 at this time. As the screw 1 continues to rotate, the volume of the working chamber will increase, forming a negative pressure. The conditions for the valve to open are:

δP<P ₁ -(P ₀ -P _v ) (2)

In the formula, P—valve opening pressure; P ₀ —atmospheric pressure; P ₁ —fluid gauge pressure in the suction chamber; P _v —vacuum degree in the working chamber. When formula (2) is satisfied, the valve core 20 is pushed open. The fluid in the first chamber 8 is sucked into the working chamber through the second circular hole 16 , the through hole 21 on the valve plate 17 , the valve gap, and the first circular hole 15 . The first chamber 8 is a suction chamber. This suction process continues until the star gear teeth are about to break away from the screw groove 4, and the volume of the working chamber reaches the maximum. As the star gear teeth disengage from the screw groove 4, the working chamber communicates with the second chamber 11, and the low-pressure fluid in the working chamber is compressed by the high-pressure fluid in the second chamber 11, and the pressure rises. The valve core 20 quickly closes the through hole 21 on the valve plate 17 under the double action of the high-pressure fluid and the spring force. When the star gear teeth on the symmetrical side star gear engage point P of the screw groove, the star gear teeth sweep out the high-pressure fluid in the screw groove and discharge it to the second chamber 11 as the meshing pair rotates. The high-pressure fluid in the second chamber 11 is discharged through the second suction/discharge hole 14 . Complete the delivery and pressurization of the fluid medium.

Embodiment 3: The pump rotates forward and the installed valve assembly is a strip valve. Referring to FIG. 7 , the valve assembly is composed of a valve plate 17 , a valve plate 22 and a lift limiter 23 . A second through hole 21 is provided on the valve plate along a direction parallel to the centerline of the valve plate, and the second through hole 21 is an eccentric hole. The valve sheet 22 is a strip-shaped metal sheet with elasticity. The lift limiter 23 is a metal sheet with high rigidity. The lift limiter 23 and the root of the valve plate 22 are fastened on the valve plate 17 by screws 24 . The valve assembly 7 is screwed into the second round hole 16 and locked, and the valve plate 22 and the lift limiter 23 are located on the side close to the first chamber 8 . The rigidity of the used valve plate 22 should not only ensure that the cracking pressure δP is not too large to avoid additional energy loss, but also ensure that the valve plate 22 can quickly adhere to the orifice of the second through hole 21 after the discharge process of the working chamber is completed.

The delivered fluid is sucked into the second chamber 11 of the pump through the second suction/discharge hole 14, and the second chamber 11 is a suction chamber. The fluid in the suction chamber enters and fills the screw groove 4 through the opening on the inverted cone on the front end face of the screw through both radial and axial directions. As the screw 1 drives the star wheel 2 to further rotate, the star wheel teeth will close the screw groove 4, at this time the volume of the working chamber reaches the maximum, and the fluid suction process is completed. As the screw 1 continues to rotate, the volume of the working chamber will decrease. When the conveyed fluid medium is a single-phase liquid medium, the liquid pressure rises rapidly. When the transported fluid medium is a two-phase flow or multiphase flow containing gas phase, as the volume of the working chamber decreases, the pressure increase law of the gas phase medium is shown in formula (1). When gas and liquid are mixed, the pressure of the liquid rises synchronously with the gas. Due to the setting of the automatic discharge valve, the internal compression of the gaseous medium can be realized automatically. No matter how the suction, discharge pressure and gas content change, the gaseous phase medium can be raised from the suction pressure to the discharge pressure in the way of internal compression, which is more labor-saving than the boosting process of the gaseous phase without internal compression, which will make the pump work in a wider range Maintain high efficiency within the range of working conditions.

When the pressure of the fluid in the working chamber is greater than the sum P ₂ +δP of the internal pressure P ₂ of the first chamber 8 and the opening pressure δP of the discharge valve, the valve plate is pushed open. The fluid in the working chamber enters the first chamber 8 through the first round hole 15 , the second round hole 16 , the second through hole 21 , and the valve gap of the strip valve. The first chamber 8 is a discharge chamber. This discharge process continues until the star gear teeth reach the first circular hole. At this time, the fluid in the first through hole 6 communicates with the low-pressure fluid filled into the screw groove again through the non-pressure bearing surface of the star gear teeth, and the pressure drops to the suction chamber. Pressure, the valve plate 22 re-closes the orifice of the second through hole 21 on the valve plate 17 under the action of the spring force and the pressure difference on both sides. After the discharge process is completed, a small amount of fluid remaining in the working chamber passes through the gap between the star wheel 2 and the screw 1 to complete unloading until the star wheel teeth break away from the screw groove. Due to the gap seal formed between the sealing section 5 of the screw and the inner wall of the cylinder, only a small amount of the fluid medium in the discharge chamber 8 flows back to the low-pressure side through the sealing section 5, and most of the fluid medium is discharged radially through the first suction/discharge hole 10 . Complete the delivery and pressurization of the fluid medium.

Embodiment 4: The pump is reversed, and the installed valve assembly is a strip valve. Referring to FIG. 8 , the valve assembly 7 is composed of a valve plate 17 , a valve plate 22 and a lift limiter 23 . A second through hole 21 is provided on the valve plate 17 along a direction parallel to the centerline of the valve plate, and the second through hole 21 is an eccentric hole. The valve sheet 22 is a strip-shaped metal sheet with elasticity. The lift limiter 23 is a metal sheet with high rigidity. The lift limiter 23 and the root of the valve plate 22 are fastened on the valve plate 17 by screws 24 . The valve assembly 7 is screwed into the second circular hole 16 and locked, and the valve plate 22 and the lift limiter 23 are located on the side close to the screw groove 4 . The rigidity of the valve plate used needs to ensure that it can be opened when the volume of the working chamber expands from 0 and a certain degree of vacuum is formed without causing a large flow loss.

The conveyed fluid is sucked into the first chamber 8 of the pump through the first suction/discharge hole 10, and the first chamber 8 is a suction chamber. As the screw 1 drives the star wheel 2 to further rotate, the star wheel teeth will engage into the screw groove 4 from the point P at the end of the screw groove 4 (the depth of the screw groove is 0), and the volume of the working chamber is 0 at this time. As the screw 1 continues to rotate, the volume of the working chamber will increase, forming a negative pressure. The condition for opening the valve is shown in formula (2). When the condition is met, the valve plate 22 is pushed open. The fluid in the first chamber 8 is sucked into the working chamber through the second through hole 21 on the valve plate 17 , the valve gap, the second round hole 16 and the first round hole 15 . The first chamber 8 is a suction chamber. This suction process continues until the star gear teeth are about to break away from the screw groove 4, and the volume of the working chamber reaches the maximum. As the star gear teeth disengage from the screw groove 4, the working chamber communicates with the second chamber 11, and the low-pressure fluid in the working chamber is compressed by the high-pressure fluid in the second chamber 11, and the pressure rises. The valve plate 22 quickly closes the second through hole on the valve plate 17 under the double action of the high-pressure fluid and the elastic force of the valve plate. When the star gear teeth on the symmetrical side star gear engage point P of the screw groove, the star gear teeth sweep out the high-pressure fluid in the screw groove and discharge it to the second chamber 11 as the meshing pair rotates. The high-pressure fluid in the second chamber 11 is discharged through the second suction/discharge hole 14 to complete the delivery and pressurization of the fluid medium.

Claims (8)

1. A kind of 1. CP types single-screw (single screw) pump, it is characterised in that the spiral shell including casing (3) and the cylindrical type being arranged in casing (3) The star-wheel (2) of bar (1) and two planes, on the basis of the line of centres of two star-wheels (2), screw rod (1) is divided into two Point；

   In Part I, screw channel (4) axially possesses complete length L along screw rod (1)₁, screw channel (4) depth changes to 0 by maximum, It is screw rod rear portion to define the part, and what is be connected on screw rod (1) with screw rod rear portion is segment hub seal section (5)；In Part II, screw channel (4) it is L along the length of screw rod (1) axial direction₂, and L₂<L₁, screw channel (4) depth changes to h by maximum₁, h₁>0, defining the part is Screw rod is anterior；It is corresponding with screw rod (1), casing (3) is divided into rear portion with anterior, at screw rod (1) rear portion, spiral groove depth is close to 0 Region and screw rod rear portion end face between offer first through hole (6), be provided with the first through hole (6) suction of control fluid or The valve member (7) of discharge process；

   Corresponding to each screw channel, offer with the identical through hole of first through hole (6) location and shape, it is logical at each It is provided with inside hole and is connected with the identical valve member of valve member 7, first through hole (6) with first chamber (8), first chamber (8) surrounded and formed by the internal face of screw rod rear portion end face, cabinet rear end cap (9) and casing (3) rear portion；At casing (3) rear portion Housing on radially open up the first suction/round (10), second chamber (11) is by the front end face of screw rod (1), casing front portion end cap (12) and the anterior internal face of casing (3) is surrounded and formed, and is connected with star-wheel chamber (13), and second is opened up radially at the front in casing Suction/round (14).
2. A kind of 2. CP types single-screw (single screw) pump according to claim 1, it is characterised in that first through hole (6) is shoulder hole, including The first circular hole (15) and the second circular hole (16) being connected, and the aperture of the first circular hole (15) is less than the hole of the second circular hole (16) Footpath, the center line of the center line and the second circular hole (16) of the first circular hole (15) is misaligned, and the second circular hole (16) offers internal thread.
3. 3. a kind of CP types single-screw (single screw) pump according to claim 1, it is characterised in that set A points as in screw profile, screw channel is deep The point for 0 is spent, B points are that the closest point with A points, A points and B points are in screw rod on the aperture of the close screw channel of the first circular hole (15) Distance radially is d, if d_minTo ensure that the hole wall of the first circular hole (15) has the d of enough rigidity and intensity minimum value, The minimum d of distance d of A points and B points in screw rod radially_min。
4. 4. a kind of CP types single-screw (single screw) pump according to claim 3, it is characterised in that set end point of the P points as screw channel, C points It is the closest point with P points on the aperture of the close screw channel of the first circular hole (15), in the case where A points and B points distance determine, The screw channel bottom land curve PD that what the first circular hole (15) opened up be located proximate on rear side of star-wheel tooth is minimum to ensure the distance of C points and P points.
5. A kind of 5. CP types single-screw (single screw) pump according to claim 1, it is characterised in that when valve member (7) be mitre valve or During spherical valve, valve member (7) includes valve plate (17), spring (18), lift limiter (19), spherical or taper valve element (20)；Valve plate (17) is to be provided with external screw thread simultaneously with the second circular hole (16) aperture identical cylinder, the face of cylinder of valve plate (17) It is engaged with the internal thread of the second circular hole (16)；It is logical that second is offered on valve plate (17) along the direction with valve plate centerline parallel Hole (21), the second through hole (21) are eccentric orfice, and lift limiter (19) is that afterbody is provided with externally threaded cylinder, lift limiter (19), spring (18) and spherical or taper valve element (20) are sequentially connected setting, and spherical or taper valve element (20) is used to block First circular hole (15) or the second through hole (21).
6. A kind of 6. CP types single-screw (single screw) pump according to claim 1, it is characterised in that when valve member (7) is beam valve, Valve member (7) is made up of valve plate (17), valve block (22) and lift limiter (23)；Valve block (22) is flexible strip gold Belong to piece, the second through hole (21) is offered on valve plate (17) along the direction with valve plate centerline parallel, the second through hole (21) is inclined Heart hole, lift limiter (23) are the higher sheet metal of rigidity, and lift limiter (23) is fastened on valve plate (17), strip valve block (22) it is used to block the second through hole 21.
7. 7. a kind of CP types single-screw (single screw) pump according to claim 1, it is characterised in that segment hub seal section (5) and casing endoporus Between leave 0.01~0.10mm unilateral gap.
8. 8. a kind of CP types single-screw (single screw) pump according to claim 1, it is characterised in that in first chamber (8) and the pump of pump One return duct is set between second chamber (11), and a return valve is set on return duct.