A plunger pump

Abstract

The present invention discloses a plunger pump, which comprises a housing, a housing side plate, an outer plunger, an inner plunger, an end cover and a crankshaft. The housing and the housing side plate enclose an outer cavity for the movement of the outer plunger. An inner cavity for the movement of the inner plunger is arranged inside the outer plunger. A straight-through shaft hole is arranged in the pump body for the crankshaft to pass through. The crankshaft is provided with an eccentric structural section for cooperating with the inner plunger. When an external driving device drives the crankshaft to rotate eccentrically, the inner plunger and the outer plunger are driven to perform reciprocating sliding; at the same time, the oil inlet and outlet holes and annular grooves of the end cover, the oil inlet and outlet channels and semi-annular grooves of the crankshaft are designed to be interconnected with the oil through holes on the inner plunger and the outer plunger to form an internal oil circuit circulation, so as to realize the rotation work of four chambers. In the plunger pump of the present invention, each cavity rotates to be the working cavity, and the pump body only involves sliding, having the remarkable advantages of fewer components, simple and compact structure, high working efficiency, high volume utilization rate, stable input and output, and being suitable for high-pressure and ultra-high-pressure application scenarios.

Description

Technical Field

[0001] The present invention belongs to the technical field of pumps for fluid transportation and pressurization, and particularly relates to a piston pump. Background Art

[0002] Pumps are widely used in daily life and various industries. In the prior art, pumps for fluid transportation and pressurization mainly include rotor type, slider type, piston type, screw type, scroll type, etc. The slider pump can maintain a gapless moving contact, has a contact pair wear compensation function, and has a long service life. However, it has the disadvantages of relatively low working efficiency, relatively high noise, large fluid pulsation, unstable working state, and small pressure ratio. The piston pump generates a pressure difference to transport fluid by the reciprocating movement of the piston rod in the cylinder, and has the advantages of high rated pressure, large capacity, and long service life. However, it has the disadvantages of complex overall structure, large floor space, and many components. In addition, the existing pumps in use all have the defect of only working in a single chamber or a double chamber, with relatively low working efficiency. Summary of the Invention

[0003] (1) Technical Problems to be Solved

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a piston pump, which has the advantages of both the slider pump and the piston pump, and can overcome the problems of few working chambers and low working efficiency of the existing pumps, large fluid pulsation and unstable state of the slider pump, and complex structure and many components of the piston pump.

[0005] (2) Technical Solutions

[0006] The present invention provides a piston pump, whose structure includes a housing, a housing side plate, an outer piston, an inner piston, an end cover, and a crankshaft;

[0007] The housing and the housing side plate enclose a columnar outer cavity, and the outer piston is slidably arranged in the outer cavity. A columnar inner cavity is horizontally opened in the outer piston, and the inner piston is slidably arranged in the inner cavity. An inner shaft hole is arranged in the inner piston along a direction perpendicular to its axial direction, and the inner shaft hole is perpendicular to the axial direction of the outer piston. A first outer shaft hole and a second outer shaft hole parallel to the inner shaft hole are respectively arranged on the housing and the outer piston. The first outer shaft hole, the second outer shaft hole, and the inner shaft hole are communicated with each other to form a through shaft hole. The crankshaft is penetrated through the through shaft hole. One end of the crankshaft extends into the end cover installed outside the housing, and the other end is connected to an external driving device. An eccentric structural section is arranged in the middle of the crankshaft, and the eccentric structural section and the inner shaft hole form a matching structure. When the crankshaft rotates eccentrically, the inner piston is driven to reciprocate sliding in the inner cavity, and when the inner piston slides, the outer piston is pushed to reciprocate sliding in the outer cavity;

[0008] An oil inlet / outlet hole and an annular groove are provided inside the end cover. Both ends of the oil inlet / outlet hole are communicated with an external oil inlet / outlet pipeline and the annular groove respectively. An oil inlet / outlet channel is axially formed inside the crankshaft. One end of the oil inlet / outlet channel is communicated with the annular groove, and the other end is communicated with a semi-annular groove arranged in the middle of the eccentric structure section. A first inner oil passage hole is axially formed inside the inner plunger, and a second inner oil passage hole is formed perpendicular to its axial direction. Both ends of the first inner oil passage hole are communicated with the semi-annular groove and the inner cavity respectively. Both ends of the second inner oil passage hole are communicated with the semi-annular groove and an external oil passage hole respectively. The external oil passage hole is axially formed along the outer plunger and is communicated with the outer cavity. This design enables the pump body to present four chambers rotating for work, with high working efficiency. The design of a single-side oil circuit also makes the structure more compact.

[0009] Preferably, the crankshaft further includes a first cylindrical section and a second cylindrical section. The first cylindrical section penetrates through the outer plunger and the housing and then extends into the end cover to communicate with the annular groove. The second cylindrical section penetrates through the outer plunger and the housing and is connected to an external driving device. The axis of the eccentric structure section is eccentrically arranged with the axes of the first and second cylindrical sections. This design can save the material cost of the crankshaft, make the end cover can be designed smaller, facilitate sealing, and make the pump body structure more compact.

[0010] Preferably, bearings are provided in the first outer shaft hole and the second outer shaft hole. The crankshaft is indirectly in contact with the first outer shaft hole and the second outer shaft hole through the bearings to ensure that when the crankshaft rotates, the outer plunger and the housing do not rotate along with the crankshaft.

[0011] Preferably, the outer plunger is a cylinder or an ellipsoid, and the inner plunger is an ellipsoid or a cylinder. The matching mode of the outer plunger and the inner plunger is outer circle and inner ellipse, or outer ellipse and inner circle, or both inner and outer ellipses. This design realizes the application of high pressure and ultra-high pressure through the matching design of the full curved surfaces of the outer plunger and the inner plunger with the outer cavity.

[0012] Preferably, the bottom surface of the inner plunger has the same area as the bottom surface of the outer plunger. This design can make the oil inlet / outlet efficiency of each cavity consistent and realize the stable input and output of oil volume during the working process.

[0013] Preferably, the outer plunger is further provided with a curved cover with a flat bottom surface. The curved cover is fixedly connected to the outer plunger and covers both ends of the inner cavity of the outer cavity.

[0014] Preferably, the two bottom surfaces of the inner plunger are curved bottom surfaces.

[0015] In the above solutions, the design of the curved cover or the curved bottom surface of the inner plunger can make the inner cavity be fully utilized without generating invalid space, improving the space utilization rate of the cavity.

[0016] Preferably, the outer oil passage hole is elliptical cylindrical or funnel-shaped with an opening facing the inner plunger; this design enables the outer oil passage hole to always communicate with the second inner oil passage hole when the outer plunger and the inner plunger move relative to each other.

[0017] Preferably, a skeleton oil seal is provided between the second cylindrical section of the crankshaft and the housing.

[0018] Preferably, sealing rings are provided at the connection between the housing side plate and the housing, and at the connection between the end cover and the housing.

[0019] (III) Beneficial Effects

[0020] One of the above technical solutions has the following advantages or beneficial effects:

[0021] 1) In the present invention, the inner cavity and the outer cavity are separated into four chambers by the inner plunger and the outer plunger. With the inner oil circuit design and the crankshaft as a single power source, the four chambers of the entire pump body work in rotation, presenting significant advantages of fewer components used, simple and compact structure, and high working efficiency.

[0022] 2) Through the design of the cylindrical or elliptical cylindrical outer plunger and the elliptical cylindrical inner plunger in the present invention, with the full-surface mating design and no corners and gaps, all-round and long-distance surface sealing between the cavities is achieved, enabling the pump body to adapt to high-pressure and even ultra-high-pressure application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, objectives, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 is a three-dimensional exploded view of Embodiment 1 of the present invention;

[0025] Figure 2 is an overall side view of the end cover of the present invention;

[0026] Figure 3 is the Figure 2 sectional view taken along plane AA of the present invention;

[0027] Figure 4 is the Figure 2 sectional view taken along plane BB of the present invention;

[0028] Figure 5 is a top perspective view of the outer plunger of the present invention (without the curved cover);

[0029] Figure 6 is a top perspective view of the inner plunger of the present invention;

[0030] Figure 7 is a schematic structural view of the crankshaft of the present invention;

[0031] Figure 8 It is a schematic diagram of the working process of the present invention;

[0032] Figure 9 It is a schematic diagram of the inner plunger structure of Embodiment 2 of the present invention;

[0033] Figure 10 It is a schematic diagram of the outer plunger structure of Embodiment 3 of the present invention;

[0034] In the figure: housing 1; outer cavity 10; first chamber 10-1; third chamber 10-2; first crankshaft hole 11; housing side plate 2; outer plunger 3; inner cavity 30; second chamber 30-1; fourth chamber 30-2; outer oil passage hole 31; second crankshaft hole 32; curved cover 33; inner plunger 4; curved bottom surface 40; inner shaft hole 41; first inner oil passage hole 42; second inner oil passage hole 43; end cover 5; oil inlet and outlet hole 51; annular groove 52; crankshaft 6; first cylindrical section 61; eccentric structure section 62; second cylindrical section 63; oil inlet and outlet passage 64; semi-annular groove 65; skeleton oil seal 7; sealing ring 8. Specific embodiments

[0035] The preferred embodiments of the present invention will be further described in detail below in conjunction with the embodiments and the drawings. However, the embodiments of the present invention also include different combinations of technical features and are not limited thereto.

[0036] Embodiment 1

[0037] As Figures 1 to 8 shown, this embodiment is a preferred solution of the present invention. The present invention provides a piston pump, and its structure includes a housing 1, a housing side plate 2, an outer plunger 3, an inner plunger 4, an end cover 5 and a crankshaft 6;

[0038] The shell 1 is connected to the shell side plate 2 by bolts to form a cylindrical outer cavity 10. The cylindrical outer plunger 3 is slidably arranged in the outer cavity 10. The outer plunger 3 reciprocates up and down in the outer cavity 10 and divides the outer cavity 10 into a first chamber 10-1 and a third chamber 10-2 relative to each other. An elliptical cylindrical inner cavity 30 is horizontally opened in the outer plunger 3. The outer plunger 3 is provided with curved covers 33 at both ends of the inner cavity 30. The curved cover 33 has a bottom surface that fits the bottom surface of the inner plunger 3 and a curved upper part that fits the shell 1. The inner plunger 4 is an elliptical cylinder, and the two bottom surfaces are elliptical planes. The elliptical bottom surface fits the outer The cylindrical bottom surface area of ​​the plunger 3 is the same to ensure that the amount of oil in and out of the chamber is the same when the chamber is working. The inner plunger 4 is slidably arranged in the inner cavity 30. The inner plunger 4 reciprocates in the inner cavity 30 and divides the inner cavity 30 into a second chamber 30-1 and a fourth chamber 30-2 relative to each other; the inner plunger 4 is provided with an inner shaft hole 41 in a direction perpendicular to the axial direction of the inner plunger 4 and the axial direction of the outer plunger 4, and the outer shell 1 and the outer plunger 3 are also respectively provided with a first outer shaft hole 11 and a second outer shaft hole 32 which are parallel to and connected with the inner shaft hole 41, and the first outer shaft hole 11, the second outer shaft hole 32 and the inner shaft hole 41 form a straight shaft hole;

[0039] like Figure 3 and Figure 7 As shown, the crankshaft 6 includes a first cylindrical section 61, an eccentric structural section 62 and a second cylindrical section 63. The eccentric structural section 62 is a cylinder with a diameter slightly larger than that of the first cylindrical section 61 and the second cylindrical section 63, and the axis of the eccentric structural section 62 is eccentrically arranged relative to the axis of the first and second cylindrical sections 61 and 63. The crankshaft 6 is through-arranged in the straight shaft hole. The first cylindrical section 61 sequentially passes through the second outer shaft hole 32 and the first outer shaft hole 11 and then extends into the end cover 5. The second cylindrical section 63 sequentially passes through the second outer shaft hole 32 and the first outer shaft hole 11 on the other side and then connects to the external drive device. The second outer shaft hole 32 and the first outer shaft hole 11 are connected to the external drive device. The outer shaft hole 11 is designed to be a through hole with a hole diameter larger than the diameter of the first and second cylindrical sections, which only provides a rotation space for the crankshaft without contact. Preferably, bearings can also be installed in the second outer shaft hole 32 and the first outer shaft hole 11, and the crankshaft 6 is indirectly in contact with the outer plunger 4 and the outer shell through the bearings; the eccentric structure section 62 of the crankshaft 6 is designed to cooperate with the inner shaft hole 41 of the inner plunger 4. When the external driving device drives the crankshaft 6 to rotate eccentrically, the inner plunger 4 is driven to slide back and forth along the inner cavity 30. When the inner plunger 4 slides, it pushes the outer plunger 3 to slide back and forth along the outer cavity 10, and the volume of each cavity changes, and oil absorption or oil discharge is performed.

[0040] like Figure 3As shown in the figure, an oil inlet / outlet hole 51 and an annular groove 52 are provided inside the end cap 5. One end of the oil inlet / outlet hole 51 communicates with the external oil inlet / outlet pipeline, and the other end communicates with the annular groove 52; an oil inlet / outlet channel 64 is axially formed in the first cylindrical section 61 of the crankshaft 6 along the axial direction of the crankshaft 6. Two semi-annular grooves 65 are provided in the middle of the eccentric structure section 62. One end of the oil inlet / outlet channel 64 communicates with the annular groove 52, and the other end penetrates through the first cylindrical section 61 and extends to the semi-annular groove 71; four oil through holes communicating with the semi-annular groove 65 are formed inside the inner plunger 4, namely two first inner oil through holes 42 symmetrically arranged along the axial direction of the inner plunger, and two second inner oil through holes 43 symmetrically arranged perpendicular to the axial direction of the inner plunger. The cross section of the second inner oil through hole 43 is elliptical. The outer plunger 3 is symmetrically provided with outer oil through holes 31 along its axial direction, and the cross section of the outer oil through holes 31 is elliptical. The first inner oil through hole 42 communicates the semi-annular groove 65 with the corresponding chamber of the inner cavity 30, and the second inner oil through hole 43 communicates the semi-annular groove 65 with the outer oil through hole 31, and further communicates with the corresponding chamber of the outer cavity 10. When in use, the oil inlet / outlet hole 51, the annular groove 52, the oil inlet / outlet channel 64, the semi-annular groove 65 and the first inner oil through hole 42, or the second inner oil through hole 43 and the outer oil through hole 31 are sequentially communicated to form an inner oil passage. As the crankshaft rotates, the chambers communicated with the semi-annular groove 65 change sequentially. When oil suction or oil discharge work is carried out in the chambers, the oil inlet or oil outlet pipeline is sequentially communicated, forming the working circuit of the pump body.

[0041] Preferably, to ensure the airtightness of the internal space of the pump body, a skeleton oil seal 7 is provided at the connection between the second cylindrical section 63 of the crankshaft 6 and the housing 1; at the connection between the housing side plate 2 and the housing 1, and at the connection between the end cap 5 and the housing, a sealing ring 8 is provided.

[0042] When the plunger pump of the present invention is working, an external driving device drives the crankshaft 6 to rotate eccentrically. Under the eccentric pushing action of the crankshaft 6, the inner plunger 4 reciprocally slides relative to the inner cavity 30, so that the second and fourth chambers (30-1, 30-2) are relatively compressed or expanded. At the same time, the inner plunger 4 pushes the outer plunger 3 to slide relative to the outer cavity 10, so that the first and third chambers (10-1, 10-2) are relatively compressed or expanded. Specifically, as Figure 8 shown, when the crankshaft rotates clockwise, starting from the first chamber 10-1 along the rotation direction of the crankshaft, the first chamber 10-1, the second chamber 30-1, the third chamber 10-2, and the fourth chamber 30-2 are sequentially compressed. The adjacent two cavities along the forward direction are sequentially communicated with the semi-annular groove 65 communicating with the oil outlet pipeline to output high-pressure liquid; starting from the third chamber 10-2 along the rotation direction of the crankshaft, the third chamber 10-2, the fourth chamber 30-2, the first chamber 10-1, and the second chamber 30-1 are sequentially expanded. The adjacent two chambers along the forward direction are sequentially communicated with the semi-annular groove 65 communicating with the oil inlet pipeline to suck in low-pressure liquid. In this way, the input and output states of each chamber are cyclically switched when the semi-annular groove 65 rotates with the crankshaft, and the chambers rotate to perform the output and input work, realizing the multi-chamber work of the pump body and improving the work efficiency.

[0043] Example 2

[0044] This embodiment is a preferred solution of the present invention. The difference between this embodiment and Embodiment 1 is that the outer plunger 3 is an elliptical cylinder, the outer cavity 10 is correspondingly arranged as an elliptical cylindrical cavity, and the inner cavity 30 is a cylindrical cavity. As Figure 9 shown, the inner plunger 4 is a cylinder with a curved bottom surface 40, and the curved surface of the curved bottom surface is designed to completely fit the shape of the outer shell 1. When the inner plunger 4 compresses the first or third chamber (10-1 or 10-2), the curved bottom surface 40 of the inner plunger 4 fits the outer shell 1, and the first or third chamber (10-1 or 10-2) is completely compressed, avoiding the existence of unusable space in the chamber and realizing the maximum utilization of the chamber volume.

[0045] Preferably, the curved bottom area of the inner plunger 3 has the same size as the elliptical bottom area of the outer plunger 3. When the inner plunger 3 and the outer plunger 3 slide, a similar volume change amount can be provided to ensure that the oil volume inhaled or output by each cavity is relatively stable;

[0046] Other components in this embodiment, the positional relationship, connection relationship, actuation relationship between components, and the functional role during use are the same as those in Embodiment 1.

[0047] Example 3

[0048] This embodiment is a preferred solution of the present invention. The differences between this embodiment and Embodiments 1 and 2 are that the outer plunger 3 and the inner plunger 4 are both designed as elliptical cylinders, the major axes of the elliptical bottom surfaces of the outer plunger 3 and the inner plunger 4 are perpendicular to each other and the bottom areas are designed to be the same size to provide a stable volume change amount; as Figure 10 shown, the outer oil through hole 31 on the outer plunger 3 is funnel-shaped, with the opening facing the inner plunger 4. When the inner plunger 4 slides relative to the outer plunger 3, the second inner oil through hole 43 is always inside the opening of the outer oil through hole 31 and communicates with it;

[0049] Other components in this embodiment, the positional relationship, connection relationship, actuation relationship between components, and the functional role during use are the same as those in Embodiment 1 or 2.

[0050] The above is only a preferred embodiment of the present invention, and it does not impose any limitation on the technical scope of the present invention. Therefore, any minor modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the present invention.

Claims

1. A plunger pump, characterized in that: It includes a housing (1), a housing side plate (2), an outer plunger (3), an inner plunger (4), an end cover (5) and a crankshaft (6); The housing (1) and the housing side plate (2) enclose a columnar outer cavity (10). The outer plunger (3) is slidably arranged in the outer cavity (10). A columnar inner cavity (30) is transversely formed in the outer plunger (3). The inner plunger (4) is slidably arranged in the inner cavity (30). An inner shaft hole (41) is arranged on the inner plunger (4) along a direction perpendicular to its axial direction. The inner shaft hole (41) is perpendicular to the axial direction of the outer plunger (3). A first outer shaft hole (11) and a second outer shaft hole (32) parallel to the inner shaft hole (41) are respectively arranged on the housing (1) and the outer plunger (3). The first outer shaft hole (11), the second outer shaft hole (32) and the inner shaft hole (41) are communicated with each other to form a straight-through shaft hole. The crankshaft (6) is arranged through the straight-through shaft hole. One end of the crankshaft (6) extends into the end cover (5) installed outside the housing (1), and the other end is connected to an external driving device. An eccentric structure section (62) is arranged in the middle of the crankshaft (6). The eccentric structure section (62) and the inner shaft hole (41) form a matching structure. When the crankshaft (6) rotates eccentrically, it drives the inner plunger (4) to slide reciprocally along the inner cavity (30). When the inner plunger (4) slides, it pushes the outer plunger (3) to slide reciprocally along the outer cavity (10); An oil inlet / outlet hole (51) and an annular groove (52) are arranged in the end cover (5). The two ends of the oil inlet / outlet hole (51) are respectively communicated with an external oil inlet / outlet pipeline and the annular groove (52). An oil inlet / outlet channel (64) is axially arranged in the crankshaft (6). One end of the oil inlet / outlet channel (64) is communicated with the annular groove (52), and the other end is communicated with a semi-annular groove (65) arranged in the middle of the eccentric structure section (62). A first inner oil through hole (42) is axially arranged in the inner plunger (4), and a second inner oil through hole (43) is arranged perpendicular to its axial direction. The two ends of the first inner oil through hole (42) are respectively communicated with the semi-annular groove (65) and the inner cavity (30). The two ends of the second inner oil through hole (43) are respectively communicated with the semi-annular groove (65) and an outer oil through hole (31). The outer oil through hole (31) is axially arranged along the outer plunger (3) and is communicated with the outer cavity (10).

2. A plunger pump according to claim 1, wherein: The crankshaft (6) further includes a first cylindrical section (61) and a second cylindrical section (63). The first cylindrical section (61) passes through the outer plunger (3) and the housing (1) and then extends into the end cover (5) to communicate with the annular groove (52). The second cylindrical section (63) passes through the outer plunger (3) and the housing (1) and then is connected to an external driving device. The axis of the eccentric structure section (62) is eccentrically arranged with the axes of the first and second cylindrical sections.

3. A plunger pump according to claim 1, characterized in that: Bearings are arranged in the first outer shaft hole (11) and the second outer shaft hole (32). The crankshaft (6) contacts the first outer shaft hole (11) and the second outer shaft hole (32) through the bearings.

4. A plunger pump according to claim 1, wherein: The outer plunger (3) is a cylinder or an elliptic cylinder, the inner plunger (4) is an elliptic cylinder or a cylinder, and the cooperation mode between the outer plunger (3) and the inner plunger (4) is outer circle and inner ellipse, or outer ellipse and inner circle, or double ellipses inside and outside.

5. A plunger pump according to claim 1, characterized in that: The bottom surface areas of the outer plunger (3) and the inner plunger (4) are the same.

6. A plunger pump according to claim 1, wherein: The outer plunger (3) is further provided with a curved cover (33) with a flat bottom surface. The curved cover (33) is fixedly connected to the outer plunger (3) and covers both ends of the inner cavity (30).

7. A plunger pump according to claim 1, wherein: Both bottom surfaces of the inner plunger (4) are curved bottom surfaces (40).

8. A plunger pump according to claim 1, characterized in that: The outer oil through hole (31) is an elliptic cylinder or a funnel shape with an opening facing the inner plunger (4).

9. A plunger pump according to claim 1, characterized in that: A skeleton oil seal (7) is provided between the side of the crankshaft (6) connected to the external driving device and the housing (1).

10. A plunger pump according to claim 1, characterized in that: Sealing rings (8) are provided at the connection between the housing side plate (2) and the housing (1) and at the connection between the end cover (5) and the housing (1).

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