Valveless piston pump with segmented piston gap

Abstract

This utility model relates to the field of fluid control valve equipment, and particularly to a valveless plunger pump with segmented plunger notches, comprising a plunger sleeve and a plunger. The plunger sleeve has an inlet and an outlet spaced apart. The plunger has a plunger notch, which is divided into a first notch segment and a second notch segment. When the plunger is assembled into the plunger sleeve, the first notch segment corresponds to the inlet position, and the second notch segment corresponds to the outlet position. The central angle of the edge of the second notch segment is less than 180°, and the central angle of the edge of the first notch segment is greater than the central angle of the second notch segment. When the plunger moves outward, the plunger opens the inlet and closes the outlet. When the plunger moves inward, the rotation angle range of the discharge between the second notch segment and the outlet is less than 180°, and when the plunger closes the outlet, the inlet is connected to the first notch segment. This utility model effectively solves the problems existing in the prior art by optimizing the structure of the plunger and adjusting the relative positions of the first and second notch segments with the inlet and outlet.

Description

Technical Field

[0001] This utility model relates to the field of fluid control valve equipment, and in particular to a valveless plunger pump with a plunger notch segment. Background Technology

[0002] Valveless plunger pumps have become increasingly popular in recent years due to their quantitative and stable liquid supply capabilities, making them increasingly prevalent in food processing applications requiring precise liquid dispensing. Existing valveless plunger pumps often feature structures like the high-precision, freely adjustable flow valveless plunger pump disclosed in patent CN222558719U. This design utilizes a notch on the plunger, which reciprocates linearly in conjunction with rotation, alternating between the notch and the plunger sleeve's inlet and outlet to facilitate liquid inflow and outflow. However, the applicant has observed that during outflow, the plunger moves from its outer limit position to its inner limit position. This linear movement involves a process of initial velocity (0), acceleration to maximum speed, and deceleration to 0, resulting in a change in the outflow velocity. Consequently, the liquid flowing from the plunger pump exhibits a characteristic of higher initial velocity followed by slower velocity at the end. This characteristic has caused challenges in some applications of valveless plunger pumps.

[0003] In applications such as the production of flavored candy beads, these beads are spheres composed of a core material containing various active ingredients blended with an internal base oil and an outer gelatinous shell. The gelatinous shell is obtained by drying water-based gelatin, pectin, etc. Flavored beads are processed using a dropper machine. The basic principle of this machine is to use a dropper with nested perforated channels... Figure 1 As shown, the middle section is the core material channel 9, and the outer section is the adhesive channel 10. The outer layer is molten adhesive. The core material is intermittently supplied and encapsulated by the continuously flowing adhesive, falling into the coolant. Due to surface tension, it shrinks into a ball of inner core material and outer adhesive. Then, it is dried to dehydrate and harden the adhesive, resulting in the finished product. A valveless plunger is used to intermittently supply core material to the core material channel 9. In the actual production of incense beads, the applicant found that the adhesive layer of the incense beads often mixed with oily core material, affecting the molding quality. After analysis, it was determined that the cause was the characteristics of the valveless plunger pump's output, which caused the initial section of the core material flowing into the adhesive (the liquid section with gradually increasing flow rate) to clump together within the adhesive, while the later section (the liquid section with gradually decreasing flow rate) easily came into contact with the adhesive and remained in the adhesive in a linear or dotted manner, resulting in the adhesive layer being mixed with core material after molding.

[0004] As can be seen from the above-mentioned application examples, the existing valveless plunger pump has the characteristic of a faster initial speed and a slower speed in the later stage, which makes it difficult to match the actual working conditions in practical applications. Therefore, the existing valveless plunger pump needs to be improved. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a valveless plunger pump with a plunger notch segment. By optimizing the structure of the plunger and adjusting the relative positions of the first and second notch segments with the inlet and outlet, the problems existing in the prior art are effectively solved.

[0006] To address the aforementioned problems, this utility model provides a valveless plunger pump with a segmented plunger notch, comprising a plunger sleeve and a plunger. One end of the plunger can be inserted into the plunger sleeve and rotate within it. The plunger sleeve has an inlet and an outlet spaced apart along its length, with the inlet located on the side of the outlet away from the sleeve opening. The end of the plunger extending into the plunger sleeve has a plunger notch, which is divided into a first notch segment and a second notch segment along the plunger's axis. When the plunger is assembled into the plunger sleeve, the first notch segment corresponds to the inlet position, and the second notch segment corresponds to the outlet position. The central angle of the edge of the second notch is less than 180°, and the central angle of the edge of the first notch is greater than the central angle of the second notch. The plunger and the plunger sleeve are arranged such that when the plunger moves in a manner that it moves from the inside out with a 180° rotation and from the outside in with a 180° rotation, when the plunger moves outward, the plunger opens the inlet and closes the outlet; when the plunger moves inward, the range of rotation angles in the discharge area where the second notch connects to the outlet is less than 180°, and when the plunger closes the outlet, the inlet connects to the first notch.

[0007] Furthermore, the central angle of the edge of the first notch segment is greater than 180°.

[0008] Furthermore, the projections of the two edges of the second notch segment are located inside the two edges of the first notch segment.

[0009] Furthermore, the plunger and the plunger sleeve are configured such that when the plunger moves inward to communicate with the outlet through the second notch section until the plunger closes the outlet, the second notch section is located inside the outlet in the axial direction of the plunger.

[0010] Alternatively, the plunger and the plunger sleeve are configured such that when the plunger moves inward to communicate with the outlet through the second notch section until the plunger closes the outlet, the second notch section is located outside the outlet in the axial direction of the plunger; the central angle of the edge of the second notch section is greater than or equal to 30° and less than or equal to 125°.

[0011] Furthermore, the plunger and the plunger sleeve are configured such that when the plunger moves inward from its outermost limit position, the plunger rotates to the range of discharge rotation angles; after the plunger moves inward to rotate out of the range of discharge rotation angles, the plunger closes the outlet and the first notch section connects to the inlet.

[0012] Alternatively, the plunger and the plunger sleeve are configured such that when the plunger moves inward from its outermost limit position, the plunger closes the outlet and the second notch section connects to the inlet; after the plunger moves inward to a set rotation angle, it enters the discharge rotation angle range.

[0013] Furthermore, the inlet is configured such that after the plunger moves outward to a predetermined distance, the inlet is located inside the inner end of the plunger.

[0014] The beneficial effect of this utility model is that by optimizing the structure of the plunger and adjusting the relative positions of the first notch segment and the second notch segment with the inlet and outlet, the problems existing in the prior art are effectively solved. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of the present invention and constitute a part of this invention, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0016] Figure 1 This is a cross-sectional structural diagram of a scented bead processing equipment used in this utility model.

[0017] Figure 2 This is a schematic diagram of the structure of the plunger sleeve and the plunger after separation according to an embodiment of the present invention.

[0018] Figure 3 for Figure 2 The illustrated embodiment shows a schematic diagram of the structure after the plunger is inserted into the plunger sleeve.

[0019] Figure 4 for Figure 3 The illustrated embodiment shows a cross-sectional view of the plunger at positions AA and BB when the plunger is in the outer limit position.

[0020] Figure 5 for Figure 3 The illustrated embodiment shows a cross-sectional view of the plunger at the inlet and outlet positions when the plunger is in the inner limit position.

[0021] Figure 6 for Figure 3 The diagram shows the liquid flow distribution of the plunger during one complete rotation cycle in the embodiment shown.

[0022] Figure 7 for Figure 3 The illustrated embodiment shows a schematic diagram of the plunger's movement during its inward movement.

[0023] The components are: 1. plunger; 2. plunger sleeve; 3. inlet; 4. outlet; 5. first notch section; 6. second notch section; 7. discharge rotation angle range; 8. inlet rotation angle range; 9. core material channel; 10. adhesive channel. Detailed Implementation

[0024] To more clearly illustrate the overall concept of this utility model, a detailed description will be provided below with reference to the accompanying drawings.

[0025] It should be noted that many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0026] Furthermore, it should be understood in the description of this utility model that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0027] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral unit; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. However, specifying a direct connection indicates that the two main bodies at the connection point are not connected by an intermediate structure, but are simply connected to form a whole through a connecting structure. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0028] In this utility model, unless otherwise expressly specified and limited, the first feature "on" or "below" the second feature may be in direct contact with the first and second features, or indirect contact through an intermediate medium. In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0029] In this utility model, such as Figure 1-7 As shown, a valveless plunger pump with a segmented plunger notch is provided, including a plunger sleeve 2 and a plunger 1. One end of the plunger 1 can be inserted into the plunger sleeve 2 and rotate within the plunger sleeve 2. The plunger sleeve 2 has an inlet 3 and an outlet 4 spaced apart along its length, with the inlet 3 located on the side of the outlet 4 away from the opening of the plunger sleeve 2. The end of the plunger 1 that extends into the plunger sleeve 2 has a plunger notch, which is divided into a first notch segment 5 and a second notch segment 6 along the axis of the plunger 1. When the plunger 1 is assembled into the plunger sleeve 2, the first notch segment 5 corresponds to the position of the inlet 3, and the second notch segment corresponds to the position of the outlet 4. The central angle of the edge of segment 6 is less than 180°, and the central angle of the edge of the first notch segment 5 is greater than the central angle of the second notch segment 6. The plunger 1 and the plunger sleeve 2 are arranged such that when the plunger 1 moves in a manner that moves from the inside out with a 180° rotation and moves from the outside in with a 180° rotation, when the plunger 1 moves outward, the plunger 1 opens the inlet 3 and closes the outlet 4; when the plunger 1 moves inward, the displacement rotation angle range 7 between the second notch segment 6 and the outlet 4 is less than 180°, and when the plunger 1 closes the outlet 4, the inlet 3 is connected to the first notch segment 5.

[0030] In use, the plunger pump of this invention can connect the inlet 3 to an external liquid supply device and the outlet 4 to an external liquid-using component. When the plunger 1 moves outward from its innermost limit position, it rotates synchronously. During this process, the plunger 1 approaches and closes the outlet 4, and the first notch section 5 connects to the inlet 3, allowing liquid to enter the plunger sleeve 2. When the plunger 1 moves inward from its outermost limit position, because the central angle of the edge of the second notch section 6 is less than 180°, and the rotation angle range 7 between the second notch section 6 and the outlet 4 is less than 180°, when the plunger 1 moves inward to push the liquid out of the plunger sleeve 2, the liquid is pushed out of the outlet 4 during part of the inward movement of the plunger 1, and then pushed out of the inlet 3 after passing through the first notch section 5 and connecting with the inlet 3.

[0031] This invention relates to a plunger pump 1. By dividing the plunger 1 notch into a first notch segment 5 and a second notch segment 6, and by limiting the range of the central angle of the edge of the second notch segment 6, only a portion of the liquid can be discharged during the inward movement of the plunger 1. Furthermore, by making the central angle of the edge of the first notch segment 5 larger than the second central angle, the range of the liquid inlet rotation angle 8 between the first notch segment 5 and the inlet 3 is larger than that of a one-piece plunger 1 notch. This increases the range of the liquid inlet rotation angle 8 between the first notch segment 5 and the inlet 3, allowing the liquid to be forced back to the inlet 3 when the plunger 1 blocks the outlet 4 during its inward movement. With this design, the outlet 4 of this invention can only discharge a portion of the liquid during the inward movement of the plunger 1. Compared to the existing valveless plunger pump's discharge process, this invention can discharge liquid within a set speed range from the outlet 4.

[0032] In a specific embodiment, the plunger 1 and the plunger sleeve are arranged such that when the plunger 1 moves inward from its outermost limit position, the plunger 1 rotates to the discharge rotation angle range 7; after the plunger 1 moves inward to rotate out of the discharge rotation angle range 7, the plunger 1 closes the outlet 4 and the first notch section 5 connects to the inlet 3.

[0033] Specific examples Figure 4 and Figure 5 As shown, when the plunger 1 moves to its outermost limit position, as it rotates further in the set rotation direction, the edge of the second notch segment 6 begins to rotate into the communication area of ​​the outlet 4, and the edge of the first notch segment 5 rotates past the inlet 3, and the curved surface of the plunger 1 closes the inlet 3. When the second notch segment 6 finishes communicating with the outlet 4, causing the curved surface of the plunger 1 at the position of the second notch segment 6 to close the outlet 4, the plunger 1 has not yet rotated 180° and has not yet moved to its innermost limit position. The first notch segment 5 begins to communicate with the inlet 3 and pushes the liquid in the plunger sleeve 2 back to the inlet 3.

[0034] By setting it up in this way, such as Figure 4 and Figure 7 As shown, Figure 7 As shown, the plunger moves inward to form the middle section (left of the vertical dotted line), which is the outlet for liquid. This allows the plunger 1 to supply liquid as it moves inward from its outer limit position. When the plunger 1 moves to the rotational discharge angle range (the plunger 1 moves at a set speed), the outlet 4 is blocked, ensuring that the end of the liquid discharged from the outlet 4 maintains a certain speed. In specific applications, this can be applied to a pelletizing machine. The plunger 1 pump of this application provides the core material. When the core material flows into the glue, the end of the core material can still maintain a certain speed (preferably, the discharge angle range can be set in the middle section formed by the linear movement of the plunger 1, so that the end of the core material maintains a higher speed), thus preventing the phenomenon of the core material remaining in the glue shell due to the slow flow rate at the end. In an optional embodiment, it can also be applied to a toy water gun, where the plunger 1 is pressed down at the front section when the water is discharged from the water gun, resulting in a gradually increasing dotted water ball pattern, preventing a slow, string-like water discharge at the end.

[0035] In another specific embodiment, distinct from Figure 3 and Figure 4 , Figure 5 In the embodiment shown, the plunger 1 and the plunger sleeve are arranged such that when the plunger 1 moves inward from its outermost limit position, the plunger 1 closes the outlet 4 and the second notch segment 6 connects to the inlet 3; after the plunger 1 moves inward to a set rotation angle, it enters the discharge rotation angle range 7.

[0036] Specifically, you can refer to Figure 3 The part shown will be explained, Figure 3 The plunger rotates to the right by a set angle. When the plunger 1 moves to its outermost limit position, as it rotates further in the set rotation direction, the first notch section 5 continues to communicate with the inlet 3, and the curved surface of the plunger 1 at the second notch section 6 closes the outlet 4. At this time, the liquid in the first section pressed down by the plunger 1 flows out through the inlet 3. When the plunger 1 rotates further by a set angle (e.g., after the set angle is greater than 90°) into the discharge rotation angle range 7, the edge of the first notch section 5 begins to communicate with the outlet 4. At the same time, the plunger 1 closes the inlet 3 at the first notch section 5, and the outlet 4 begins to supply liquid.

[0037] This configuration ensures that as plunger 1 moves inward from its outer limit position, it forces the liquid back to inlet 3. When plunger 1 reaches the rotation angle range for discharging liquid (plunger 1 moves at a set speed), outlet 4 is blocked, maintaining a certain speed at the beginning of the liquid discharged from outlet 4. When plunger 1 moves inward to its inner limit position and the edge of the second notch segment 6 contacts outlet 4 (plunger 1 is about to close outlet 4 at the second notch segment 6), the final speed of the liquid discharged from outlet 4 is low (approaching 0), resulting in a string-like discharge of the liquid. In specific applications, this can be used in the processing of stick-shaped sandwich foods. This plunger 1 pump provides the core material, allowing it to be linearly distributed after entering the adhesive. Compared to existing plunger 1 pump liquid supply methods, this reduces the localized excessive core material volume caused by clumping in the core material at the beginning of the discharge (low speed at the beginning of the discharge, and clumping in the middle of the discharge as it catches up with the beginning).

[0038] In a preferred embodiment, more specifically, regarding the structure of this utility model, the central angle of the edge of the first notch segment 5 is greater than 180°.

[0039] With this setup, the liquid inlet rotation angle range 8 between the first notch section 5 and the inlet 3 can be greater than 180° without designing or modifying the original outlet 4 dimensions.

[0040] like Figure 2 As shown, during the inward and outward movement of the plunger 1, the inlet 3 is located on the side of the first notch section 5. By controlling the central angle of the inlet 3 to match the central angle of the first notch section 5, the liquid inlet rotation angle range 8 of the plunger 1 connected to the inlet 3 in the first notch section 5 can be adjusted so that the sum of the liquid inlet rotation angle range 8 and the liquid outlet angle range is 360°.

[0041] In the illustrated embodiment, more specifically, regarding the structure of this utility model, the projections of the two edges of the second notch segment 6 are located inside the two edges of the first notch segment 5.

[0042] like Figure 2 As shown, this allows the second notch section 6 to connect with the outlet 4, and when the plunger 1 moves inward, the liquid at the inner end of the plunger 1 can pass through the first notch section 5 more smoothly into the position of the second notch section 6 and flow out.

[0043] In the illustrated embodiment, for the structure of this utility model, the plunger 1 and the plunger sleeve 2 are arranged such that when the plunger 1 moves inward to connect with the outlet 4 through the second notch segment to the outlet 4, the second notch segment is located outside the outlet 4 in the axial direction of the plunger 1; the central angle of the edge of the second notch segment 6 is greater than or equal to 30° and less than or equal to 125°.

[0044] Specifically, this allows the second notch section 6 to be rotated to the side of the outlet 4 while liquid is being supplied outward through the connection between the second notch section 6 and the outlet 4, thereby closing the outlet 4 with the plunger 1. This allows for a convenient and accurate determination of the plunger 1's discharge rotation angle range 7 by calculating the central angle of the outlet 4 and the central angle of the edge of the second notch section 6.

[0045] The method by which the plunger closes the outlet at the second notch is not limited to the method shown in the figure, which only closes the outlet through the side portion of the second notch. In alternative embodiments, for the structure of this utility model, more specifically, the plunger 1 and the plunger sleeve 2 are arranged such that when the plunger 1 moves inward to connect with the outlet 4 through the second notch and when the plunger 1 closes the outlet 4, the second notch is located inside the outlet 4 in the axial direction of the plunger 1.

[0046] Specifically, this allows the second notch section 6 to be moved to the inside of the outlet 4 by axial movement of the plunger rod while the second notch section 6 is connected to the outlet 4 and liquid is being transported outwards, thereby achieving the closure of the outlet 4 by the plunger 1. This reduces the upper limit of the central angle of the edge of the second notch section 6, and thus allows for an appropriate increase in the central angle of the edge of the second notch section 6, thereby increasing the notch area at the location of the second notch section 6 and improving the liquid flow capacity.

[0047] In the illustrated embodiment, during the inward and outward movement of the plunger, the inlet is always located to the side of the first notch segment, and the connection of the inlet begins and ends at the edge of the notch segment. This is not intended to limit the present invention. In optional embodiments, for the structure of the present invention, more specifically, the inlet 3 is configured such that after the plunger 1 moves outward to a set distance, the inlet 3 is located inside the inner end of the plunger 1.

[0048] In the embodiment where liquid is expelled from the latter part of the inward movement of plunger 1, the inlet can be positioned in the lower region of plunger sleeve 2. This allows plunger 1 to disengage from inlet 3 when it moves outward a set distance (e.g., halfway through the stroke), thus maintaining communication between plunger 1 and inlet 3. After plunger 1 moves inward to the set distance, it moves to a position where it can close inlet 3. At this point, plunger 1 can close inlet 3, allowing liquid expelled from the latter part of the inward movement of plunger 1 to be output when the second notch section 6 connects with outlet 4.

[0049] By setting it this way, the lower limit of the angle of the second notch segment can be reduced.

[0050] It should be noted that the improvement of this utility model lies in the fitting structure between the plunger sleeve 2 and the plunger 1. The external pipeline connection structure of the driving component, inlet and outlet of the plunger 1 is not restricted or improved. Those skilled in the art can implement it according to other feasible structural components.

[0051] It should be noted that the plunger described in this utility model moves in a manner that involves moving from the inside out while rotating 180°, and moving from the outside in while rotating 180°. This refers to the fixed reciprocating movement and rotational coordination of the plunger in a plunger pump. In a specific embodiment, the cast stone rotates at a uniform speed, and the linear movement of the plunger is shown in the attached figure. Figure 7 Move as shown.

[0052] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0053] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A valveless plunger pump with segmented plunger notches, comprising a plunger sleeve and a plunger, one end of the plunger being insertable into and rotatable within the plunger sleeve, characterized in that, The plunger sleeve is provided with an inlet and an outlet at intervals along its length, and the inlet is located on the side of the outlet away from the opening of the plunger sleeve; The plunger has a plunger notch at one end that extends into the plunger sleeve. The plunger notch is divided into a first notch segment and a second notch segment along the axis of the plunger. When the plunger is assembled into the plunger sleeve, the first notch segment corresponds to the inlet position and the second notch segment corresponds to the outlet position. The central angle of the edge of the second notch segment is less than 180°, and the central angle of the edge of the first notch segment is greater than the central angle of the second notch segment. The plunger and the plunger sleeve are arranged such that when the plunger moves in a manner that it moves from the inside out with a 180° rotation and from the outside in with a 180° rotation, When the plunger moves outward, the plunger opens the inlet and closes the outlet; When the plunger moves inward, the range of the discharge rotation angle between the second notch section and the outlet is less than 180°, and when the plunger closes the outlet, the inlet is connected to the first notch section.

2. The plunger pump according to claim 1, characterized in that, The central angle of the edge of the first notch segment is greater than 180°.

3. The plunger pump according to claim 1 or 2, characterized in that, The projections of the two edges of the second notch segment are located inside the two edges of the first notch segment.

4. The plunger pump according to claim 1, characterized in that, The plunger and the plunger sleeve are configured such that when the plunger moves inward to communicate with the outlet through the second notch section until the plunger closes the outlet, the second notch section is located inside the outlet in the axial direction of the plunger.

5. The plunger pump according to claim 1, characterized in that, The plunger and the plunger sleeve are configured such that when the plunger moves inward to communicate with the outlet through the second notch section until the plunger closes the outlet, the second notch section is located outside the outlet in the axial direction of the plunger; the central angle of the edge of the second notch section is greater than or equal to 30° and less than or equal to 125°.

6. The plunger pump according to claim 1, characterized in that, The plunger and the plunger sleeve are configured such that when the plunger moves inward from its outermost limit position, the plunger rotates to the range of liquid discharge rotation angles. After the plunger moves inward to the range of rotation angles for discharging liquid, the plunger closes the outlet and the first notch section connects to the inlet.

7. The plunger pump according to claim 1, characterized in that, The plunger and the plunger sleeve are configured such that when the plunger moves inward from its outermost limit position, the plunger closes the outlet and the second notch section connects to the inlet. The plunger moves inward to a set rotation angle and then enters the discharge rotation angle range.

8. The plunger pump according to claim 1, characterized in that, The inlet is configured such that after the plunger moves outward to a predetermined distance, the inlet is located inside the inner end of the plunger.

Images