Straight-line oil pump and method of operation thereof

Abstract

This invention discloses a linear oil pump and its operating method, comprising a pump body, a guide device, a piston assembly, a one-way device, and a pump rod. The guide device is installed at the top open end of the pump body along its axial direction. The piston assembly is arranged in the pump body and has two working states: opening to open the oil passage and closing to cut off the oil passage. The one-way device is arranged in the pump body between the guide device and the piston assembly, dividing the pump body cavity between the guide device and the piston assembly into an upper cavity and a lower cavity along its axial direction. The one-way device also has two working states: opening to open the oil passage and closing to cut off the oil passage. The pump body is provided with an oil outlet and an oil suction port. The pump rod passes sequentially through the guide device, the one-way device, and the piston assembly, and the pump rod drives the piston assembly to move linearly along its axial direction within the pump body. Thus, the oil pump extends and retracts linearly in one cycle, pumping oil out twice, thereby improving working efficiency and reducing system pressure fluctuations.

Description

Technical Field

[0001] This invention relates to a linear oil pump, belonging to the field of oil pump technology. Background Technology

[0002] Linear oil pumps have advantages such as high rated pressure and compact structure, and are widely used in industries such as engineering machinery, chemical industry, and metallurgy.

[0003] Existing technical solution diagram, such as Figure 1 As shown. During one cycle of linear extension and retraction of the rod, the oil pump only pumps oil out once. When rod 100 extends into pump body 200, the pressure in closed cavity 500 decreases, and oil is drawn into the closed cavity through check valve 300; when rod 100 retracts into pump body 200, the pressure in closed cavity 500 increases, and oil is pumped out through check valve 400.

[0004] The straight extension and retraction cycle results in the oil pump pumping oil out only once, which has the disadvantages of low working efficiency and large system pressure fluctuations. Summary of the Invention

[0005] To address the above problems, the purpose of this invention is to improve working efficiency and reduce system pressure fluctuations by having the oil pump extend and retract in a straight line in one cycle, pumping oil out twice.

[0006] This invention is implemented according to the following technical solution: In a first aspect, the present invention provides a linear oil pump, comprising: Hollow pump body; A guide device is installed at the top opening end of the pump body along its axial direction; A piston assembly is arranged in the pump body, and the piston assembly has two working states: opening to open the oil passage and closing to cut off the oil passage. A one-way device is arranged in the pump body located between the guide device and the piston assembly, dividing the pump body cavity between the guide device and the piston assembly into an upper cavity and a lower cavity in the axial direction. The one-way device has two working states: opening to open the oil passage and closing to cut off the oil passage. An oil outlet is provided on the pump body above the one-way device, and an oil suction port is provided on the pump body below the one-way device. The pump rod is sequentially inserted through the guide device, the one-way device and the piston assembly, and the pump rod drives the piston assembly to move axially linearly within the pump body; When the pump rod extends, the one-way device opens, the volume of the entire pump body cavity decreases, the pressure increases, the piston assembly closes, and the oil is pumped out from the oil outlet. When the pump rod retracts, the volume of the upper cavity decreases and the pressure increases, the one-way device closes, and the oil is pumped out from the oil outlet; the volume of the lower cavity increases and the pressure decreases, the piston assembly opens, and the oil is replenished to the lower cavity through the piston assembly to prevent vacuum cavitation.

[0007] In some embodiments, the pump rod is stepped, the outer diameter of the piston assembly is d1, the outer diameter of the pump rod inserted into the guide device is d2, and the outer diameter of the pump rod inserted into the one-way device is d3, where d1>d2>d3.

[0008] In some embodiments, the unidirectional device includes: A valve seat is fixed on the inner circumferential surface of the pump body. The valve seat is provided with a central through hole I, and the pump rod passes through the central through hole I. A valve core is arranged on the valve seat. The valve core has a central through hole II arranged coaxially with the central through hole I. The pump rod passes through the central through hole II. The valve core can move within a preset range along the pump rod axis. The valve core and the valve seat are coupled in the following way: When the lower surface of the valve core is in contact with the upper surface of the valve seat, the one-way device is in a closed state, separating the upper cavity and the lower cavity, and the oil circuits of the two are not connected. When the lower surface of the valve core separates from the upper surface of the valve seat, the one-way device is in the open state, connecting the upper cavity and the lower cavity, and the oil circuits of the two are connected.

[0009] In some embodiments, a gap a is left between the central through hole I and the pump rod, a gap b is left between the outer circumferential surface of the valve core and the inner circumferential surface of the pump body, and an O-ring seal is provided between the opposing circumferential surfaces of the valve core and the pump rod to prevent oil from flowing out of the central through hole II; When the lower surface of the valve core is in contact with the upper surface of the valve seat, gap a and gap b are not connected. When the lower surface of the valve core separates from the upper surface of the valve seat, gap a and gap b are connected, and the oil in the lower cavity enters the upper cavity through the one-way device and is pumped out from the oil outlet.

[0010] In some embodiments, the valve core is composed of a base with a frustum-shaped lower part and a top seat with a petal-shaped upper part connected together. The outer diameter of the widest part of the bottom of the base is smaller than the inner diameter of the pump body, thus forming the gap b. The top seat has a plurality of protrusions evenly spaced along the circumference. Each protrusion contacts the inner circumferential surface of the pump body and guides the movement of the one-way device. The oil flows through the gap c between two adjacent protrusions. When the one-way device moves upward, it is limited by the steps set on the inner circumferential surface of the pump body.

[0011] In some embodiments, the piston assembly includes: A cover plate is fitted onto the bottom of the pump rod, and the cover plate can move within a preset range along the pump rod axis; A piston is fitted onto the bottom of the pump rod and located below the cover plate. The piston is fixed to the pump rod by fasteners, and an oil passage is provided between the piston and the pump rod. The inlet of the oil passage is located on the bottom end face or outer circumferential surface of the pump rod below the piston, and the outlet of the oil passage is located on the upper surface of the piston in contact with the cover plate. The fit between the cover plate and the piston is as follows: When the lower surface of the cover plate is in contact with the upper surface of the piston, the piston assembly is in a closed state, and the flow of oil from the bottom of the piston assembly into the lower cavity is cut off by blocking the oil passage. When the lower surface of the cover plate separates from the upper surface of the piston, the piston assembly is in the open state, and the oil passage below the piston assembly is opened to allow the oil to flow into the lower cavity.

[0012] In some embodiments, the bottom outer circumferential surface of the pump rod is provided with an external thread, a step I, and a step II spaced from bottom to top. The piston is fitted onto the pump rod between the external thread and step I. The fastener is a lock nut, which is tightened onto the external thread of the pump rod, pressing the upper surface of the piston against step I. The cover plate is fitted onto the pump rod between step I and step II, and the thickness of the cover plate is less than the distance between step I and step II. When the cover plate moves upward, it is limited by step II. The outer diameter of the cover plate is smaller than the inner diameter of the pump body, thus forming the gap d.

[0013] In some embodiments, the inlet of the oil passage is located on the bottom end face of the pump rod in the axial direction, and there are multiple outlets of the oil passage, which are located on the upper surface of the piston and distributed circumferentially at intervals; the oil passage is implemented in the following manner: Oil passage a extends vertically upward from the inlet, and multiple oil passages b extend horizontally outward into the piston. Multiple oil passages c extend vertically upward from each oil passage b to the piston outlet.

[0014] In some embodiments, the pump body is a two-section assembled structure, consisting of pump body I and pump body II joined together; the bottom of the one-way device is fixed to the joint of the pump body, and the part below the joint of the pump body is completely immersed in the oil; the bottom of the pump body in the axial direction is set as an open end, and multiple through holes are provided on the radial circumferential surface of the pump body near the open end, and the open end and the multiple through holes together form the oil suction port.

[0015] Secondly, the present invention provides a method for operating a linear oil pump based on the above-mentioned method, comprising the following: When the pump rod extends, the outer diameter d1 of the piston assembly is greater than the outer diameter d2 of the pump rod inserted into the guide device. The valve core and valve seat in the one-way device separate. At this time, the one-way device is in the open state, and the upper cavity and the lower cavity are connected. The volume of the entire pump body cavity becomes smaller and the pressure increases. The lower surface of the cover plate in the piston assembly is in contact with the upper surface of the piston. At this time, the piston assembly is in the closed state. By blocking the oil passage in the piston assembly, the channel for the oil below the piston assembly to flow into the lower cavity is cut off. The oil in the lower cavity enters the upper cavity after passing through the gap between the valve seat and the pump rod, the gap between the valve core and the valve seat, and the gap between the valve core and the pump rod in sequence, and is pumped out from the oil outlet. When the pump rod retracts, the outer diameter d2 of the pump rod inserted into the guide device is greater than the outer diameter d3 of the pump rod inserted into the one-way device. The volume of the upper cavity decreases and the pressure increases. The lower surface of the valve core in the one-way device is in contact with the upper surface of the valve seat. At this time, the one-way device is in a closed state, and the upper cavity is isolated from the lower cavity. The oil in the upper cavity is pumped out from the oil outlet. The volume of the lower cavity increases and the pressure decreases. The lower surface of the cover plate in the piston assembly separates from the upper surface of the piston. The oil below the piston assembly passes through the oil passage between the piston and the pump rod, the gap between the cover plate and the piston, and the gap between the cover plate and the pump body in sequence to replenish the lower cavity, preventing vacuum cavitation.

[0016] Beneficial effects of this invention: When the pump rod extends, it pumps oil out once; when the pump rod retracts, it pumps oil out once more, simultaneously preventing vacuum cavitation. In other words, one cycle of the pump rod extending and retracting linearly pumps oil out twice, increasing efficiency and reducing system pressure fluctuations. Attached Figure Description

[0017] The accompanying drawings, as part of this invention, are provided to further illustrate the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation thereof. Clearly, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0018] In the attached diagram: Figure 1 This is a schematic diagram of a linear oil pump based on existing technology. Attached diagram labels: 100-rod; 200-pump body; 300-check valve; 400-check valve; 500-closed cavity.

[0019] Figure 2 This is a cross-sectional view of the overall structure of the linear oil pump of the present invention; Attached diagram labels: 1-Pump body I; 2-Pump body II; 3-Pump rod; 4-Guide device; 5-Valve seat; 6-Valve core; 7-Piston; 8-Cover plate; 9-Locking nut; 10-Oil passage; 63-O-ring seal; S-Inlet; P-Outlet; A-Upper cavity; B-Lower cavity.

[0020] Figure 3 This is an overall structural diagram of the valve core of the present invention; Attached diagram labels: 61-base; 62-top.

[0021] Figure 4 This is a cross-sectional view of the linear oil pump of the present invention after the pump rod has been extended; Attached diagram labels: 1-Pump body I; 2-Pump body II; 3-Pump rod; 4-Guide device; 5-Valve seat; 6-Valve core; 7-Piston; 8-Cover plate; 9-Locking nut; S-Inlet; P-Outlet; A-Upper cavity; B-Lower cavity.

[0022] Figure 5 This is a cross-sectional view of the linear oil pump of the present invention after the pump rod is retracted. Attached diagram labels: 1-Pump body I; 2-Pump body II; 3-Pump rod; 4-Guide device; 5-Valve seat; 6-Valve core; 7-Piston; 8-Cover plate; 9-Locking nut; S-Inlet; P-Outlet; A-Upper cavity; B-Lower cavity.

[0023] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0025] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "horizontal", "vertical", "inner", "outer", etc., 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 invention 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 invention.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] like Figure 2 , Figure 4 , Figure 5 As shown, a linear oil pump includes a hollow pump body, a guide device 4, a piston assembly, a one-way device, and a pump rod 3. The guide device 4 is installed at the top open end of the pump body along the axial direction. The piston assembly is arranged in the pump body and has two working states: opening to open the oil passage and closing to cut off the oil passage. The one-way device is arranged in the pump body between the guide device 4 and the piston assembly, dividing the pump body cavity between the guide device 4 and the piston assembly into an upper cavity A and a lower cavity B in the axial direction. The one-way device has two working states: opening to open the oil passage and closing to cut off the oil passage. An outlet is provided on the pump body above the one-way device. Oil outlet P; oil suction port S is provided on the pump body below the one-way device; pump rod 3 passes through guide device 4, one-way device and piston assembly in sequence, pump rod 3 drives piston assembly to move axially linearly in the pump body; when pump rod 3 extends, one-way device opens, the entire cavity of pump body decreases in volume, pressure increases, piston assembly closes, oil is pumped out from oil outlet P; when pump rod 3 retracts, upper cavity A decreases in volume, pressure increases, one-way device closes, oil is pumped out from oil outlet P; lower cavity B increases in volume, pressure decreases, piston assembly opens, oil is supplied to lower cavity B through piston assembly to prevent vacuum cavitation.

[0028] As can be seen, this invention provides a linear oil pump that pumps oil out once when the pump rod extends and once when the pump rod retracts, while simultaneously preventing vacuum cavitation. That is, one cycle of the pump rod extending and retracting linearly pumps oil out twice, increasing working efficiency and reducing system pressure fluctuations.

[0029] The following provides a further explanation of the specific structure of the pump rod described above.

[0030] like Figure 2 , Figure 4 , Figure 5 As shown, the pump rod 3 is stepped, the outer diameter of the piston assembly is d1, the outer diameter of the pump rod 3 inserted into the guide device 4 is d2, and the outer diameter of the pump rod 3 inserted into the one-way device is d3, where d1>d2>d3.

[0031] Specifically, when pump rod 3 extends, d1 > d2, the one-way device opens, the entire cavity volume decreases, the pressure increases, the piston assembly closes, and oil is pumped out from the oil outlet P; when pump rod 3 retracts, d2 > d3, the upper cavity A volume decreases, the pressure increases, the one-way device closes, and oil is pumped out from the oil outlet P; the lower cavity B volume increases, the pressure decreases, the piston assembly opens, and oil is replenished to the lower cavity B through the internal oil passages of pump rod 3 and piston 7 to prevent vacuum cavitation.

[0032] The following provides a further explanation of the specific structure of the aforementioned one-way device.

[0033] like Figure 2 , Figure 4 , Figure 5 As shown, the one-way device includes a valve seat 5 and a valve core 6. The valve seat 5 is fixed on the inner circumferential surface of the pump body and has a central through hole I, through which the pump rod 3 passes. The valve core 6 is arranged on the valve seat 5 and has a central through hole II coaxially arranged with the central through hole I, through which the pump rod 3 passes. The valve core 6 can move along the axial direction of the pump rod 3 within a preset range. The cooperation method between the valve core 6 and the valve seat 5 is as follows: When the lower surface of the valve core 6 is in contact with the upper surface of the valve seat 5, the one-way device is in a closed state, separating the upper cavity A and the lower cavity B, and the oil circuits of the two are not connected. When the lower surface of the valve core 6 separates from the upper surface of the valve seat 5, the one-way device is in the open state, connecting the upper cavity A and the lower cavity B, and the oil circuits of the two are connected.

[0034] Further options, such as Figure 2 , Figure 4 , Figure 5 As shown, a gap a is left between the central through hole I and the pump rod 3, and a gap b is left between the outer circumferential surface of the valve core 6 and the inner circumferential surface of the pump body. An O-ring seal 63 is provided between the opposing circumferential surfaces of the valve core 6 and the pump rod 3 to prevent oil from flowing out of the central through hole II. When the lower surface of the valve core 6 is in contact with the upper surface of the valve seat 5, gap a and gap b are not connected. When the lower surface of the valve core 6 is separated from the upper surface of the valve seat 5, gap a and gap b are connected, and the oil in the lower cavity B enters the upper cavity A through the one-way device and is pumped out from the oil outlet P.

[0035] The following provides a further explanation of the specific structure of the valve core described above.

[0036] like Figure 3As shown, the valve core 6 is composed of a base 61 with a frustum-shaped lower part and a top seat 62 with a petal-shaped upper part. The outer diameter of the widest part of the bottom of the base 61 is smaller than the inner diameter of the pump body, thus forming a gap b. The top seat 62 has multiple protrusions evenly spaced along the circumference. Each protrusion contacts the inner circumferential surface of the pump body and guides the movement of the one-way device. The oil flows through the gap c between two adjacent protrusions. When the one-way device moves upward, it is limited by the steps set on the inner circumferential surface of the pump body.

[0037] Specifically, such as Figure 3 As shown, the top seat 62 has three protrusions evenly spaced along the circumference. Of course, it is not limited to the above three; it can also be four or five. The outer surface of the protrusions is designed as an arc-shaped surface for fitting against the inner circumferential surface of the pump body.

[0038] The specific structure of the aforementioned guiding device will be further explained below.

[0039] like Figure 2 , Figure 4 , Figure 5 As shown, the guide device 4 has a T-shaped cross-section. The guide device 4 is fixed to the pump body by peripheral bolts. An O-ring seal is provided between the circumferential surfaces of the guide device 4 and the pump rod 3 to prevent oil from flowing out from the gap between them.

[0040] The following provides a further explanation of the specific structure of the piston assembly described above.

[0041] like Figure 2 , Figure 4 , Figure 5 As shown, the piston assembly includes a cover plate 8 and a piston 7. The cover plate 8 is fitted onto the bottom of the pump rod 3 and can move within a preset range along the axial direction of the pump rod 3. The piston 7 is fitted onto the bottom of the pump rod 3 and is located below the cover plate 8. The piston 7 is fixed to the pump rod 3 by fasteners, and an oil passage 10 is provided between the piston 7 and the pump rod 3. The inlet of the oil passage 10 is located on the bottom end face or outer circumferential surface of the pump rod 3 below the piston 7, and the outlet of the oil passage 10 is located on the upper surface of the piston 7 in contact with the cover plate 8. The fit between the cover plate 8 and the piston 7 is as follows: When the lower surface of the cover plate 8 is in contact with the upper surface of the piston 7, the piston assembly is in a closed state, and the oil flow from the piston assembly to the lower cavity B is cut off by blocking the oil passage 10. When the lower surface of the cover plate 8 separates from the upper surface of the piston 7, the piston assembly is in the open state, and the oil passage 10 is opened to guide the oil below the piston assembly into the lower cavity B.

[0042] Further options, such as Figure 2 , Figure 4 , Figure 5 As shown, the bottom outer circumferential surface of the pump rod 3 is provided with external threads, step I and step II at intervals from bottom to top. The piston 7 is fitted onto the pump rod 3 between the external threads and step I. The fastener is a lock nut 9, which is tightened at the external threads of the pump rod 3, pressing the upper surface of the piston 7 against step I. The cover plate 8 is fitted onto the pump rod 3 between step I and step II, and the thickness of the cover plate 8 is less than the distance between step I and step II. When the cover plate 8 moves upward, it is limited by step II. The outer diameter of the cover plate 8 is smaller than the inner diameter of the pump body, thus forming a gap d.

[0043] Further options, such as Figure 2 , Figure 4 , Figure 5 As shown, the inlet of oil passage 10 is located on the bottom end face of pump rod 3 along the axial direction, and there are multiple outlets of oil passage 10. These multiple outlets are located on the upper surface of piston 7 and are distributed circumferentially at intervals. Oil passage 10 is implemented in the following manner: Oil passage a extends vertically upward from the inlet, and multiple oil passages b extend horizontally outward into the piston 7. Multiple oil passages c extend vertically upward from each oil passage b to the piston outlet.

[0044] It should be noted that the above provides a specific embodiment of the oil passage, and is not limited to the above structure; other forms of oil passage structures are also possible.

[0045] The following provides a further explanation of the specific structure of the pump body described above.

[0046] like Figure 2 , Figure 4 , Figure 5 As shown, the pump body is a two-section assembled structure, consisting of pump body I1 and pump body II2 connected together; the bottom of the one-way device is fixed to the connection point of the pump body, and the part of the pump body below the connection point is completely immersed in the oil; the bottom of the pump body in the axial direction is set as an open end, and multiple through holes are provided on the radial circumference of the pump body near the open end, and the open end and multiple through holes together form the oil suction port S.

[0047] Specifically, the bottom of pump body I1 is provided with internal threads, the top of pump body II2 is provided with external threads, pump body I1 and pump body II2 are connected by threads, valve seat 5 is snapped into the joint of pump body I1 and pump body II2, guide device 4 is fixed at the top opening end of pump body I1, oil outlet P is set on pump body I1 near guide device 4, and oil suction port S is set on pump body II2.

[0048] like Figure 4As shown, when the pump rod 3 extends, the outer diameter d1 of the piston 7 is greater than the outer diameter d2 of the pump rod 3 inserted into the guide device 4. The valve core 6 in the one-way device separates from the valve seat 5. At this time, the one-way device is in the open state, and the upper cavity A and the lower cavity B are connected. The volume of the entire pump body cavity becomes smaller and the pressure increases. The lower surface of the cover plate 8 in the piston assembly is in contact with the upper surface of the piston 7. At this time, the piston assembly is in the closed state. By blocking the oil passage 10 in the piston assembly, the channel for the oil below the piston assembly to flow into the lower cavity B is cut off. The oil in the lower cavity B passes through the gap between the valve seat 5 and the pump rod 3, the gap between the valve core 6 and the valve seat 5, and the gap between the valve core 6 and the pump rod 3 in sequence before entering the upper cavity A and being pumped out from the oil outlet P.

[0049] like Figure 5 As shown, when the pump rod 3 retracts, the outer diameter d2 of the pump rod 3 inserted into the guide device 4 is greater than the outer diameter d3 of the pump rod 3 inserted into the one-way device. The volume of the upper cavity A decreases and the pressure increases. The lower surface of the valve core 6 in the one-way device is in contact with the upper surface of the valve seat 5. At this time, the one-way device is in a closed state, and the upper cavity A is isolated from the lower cavity B. The oil in the upper cavity A is pumped out from the oil outlet P. The volume of the lower cavity B increases and the pressure decreases. The lower surface of the cover plate 8 in the piston assembly separates from the upper surface of the piston 7. The oil below the piston assembly passes through the oil passage 10 between the piston 7 and the pump rod 3, the gap between the cover plate 8 and the piston 7, and the gap between the cover plate 8 and the pump body in sequence before replenishing the lower cavity B to prevent vacuum cavitation.

[0050] In summary, this invention provides a linear oil pump with a pump rod having two outer diameters d2 and d3, and a piston outer diameter d1 > d2 > d3; it is equipped with a one-way device, which separates the upper and lower cavities when the lower surface of the valve core is in contact with the upper surface of the valve seat, and opens the upper and lower cavities when the lower surface of the valve core is separated from the upper surface of the valve seat; it is equipped with a piston assembly, and oil passages are provided at the bottom of the pump rod and inside the piston; when the lower surface of the cover plate is in contact with the upper surface of the piston, it seals the passage between the lower cavity and the oil below the piston assembly, and when the lower surface of the cover plate is separated from the upper surface of the piston, it opens the passage between the lower cavity and the oil below the piston assembly; the pump body is divided into two sections, which are mechanically connected and fixed to the one-way device valve seat.

[0051] When the pump rod extends, it pumps oil out once; when the pump rod retracts, it pumps oil out once more, simultaneously preventing vacuum cavitation. In other words, one cycle of the pump rod extending and retracting linearly pumps oil out twice, increasing efficiency and reducing system pressure fluctuations.

[0052] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0053] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features found in other embodiments but not others, combinations of features from different embodiments are also within the scope of protection of this invention and form different embodiments. For example, in the embodiments described above, those skilled in the art can use them in combination based on known technical solutions and the technical problems to be solved by this application.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A linear oil pump, characterized in that, include: Hollow pump body; A guide device is installed at the top opening end of the pump body along its axial direction; A piston assembly is arranged in the pump body, and the piston assembly has two working states: opening to open the oil passage and closing to cut off the oil passage. A one-way device is arranged in the pump body located between the guide device and the piston assembly, dividing the pump body cavity between the guide device and the piston assembly into an upper cavity and a lower cavity in the axial direction. The one-way device has two working states: opening to open the oil passage and closing to cut off the oil passage. An oil outlet is provided on the pump body above the one-way device, and an oil suction port is provided on the pump body below the one-way device. The pump rod is sequentially inserted through the guide device, the one-way device and the piston assembly, and the pump rod drives the piston assembly to move axially linearly within the pump body; When the pump rod extends, the one-way device opens, the volume of the entire pump body cavity decreases, the pressure increases, the piston assembly closes, and the oil is pumped out from the oil outlet. When the pump rod retracts, the volume of the upper cavity decreases and the pressure increases, the one-way device closes, and the oil is pumped out from the oil outlet; the volume of the lower cavity increases and the pressure decreases, the piston assembly opens, and the oil is replenished to the lower cavity through the piston assembly to prevent vacuum cavitation.

2. The linear oil pump according to claim 1, characterized in that, The pump rod is stepped, the outer diameter of the piston assembly is d1, the outer diameter of the pump rod inserted into the guide device is d2, and the outer diameter of the pump rod inserted into the one-way device is d3, where d1>d2>d3.

3. The linear oil pump according to claim 1, characterized in that, The unidirectional device includes: A valve seat is fixed on the inner circumferential surface of the pump body. The valve seat is provided with a central through hole I, and the pump rod passes through the central through hole I. A valve core is arranged on the valve seat. The valve core has a central through hole II arranged coaxially with the central through hole I. The pump rod passes through the central through hole II. The valve core can move within a preset range along the pump rod axis. The valve core and the valve seat are coupled in the following way: When the lower surface of the valve core is in contact with the upper surface of the valve seat, the one-way device is in a closed state, separating the upper cavity and the lower cavity, and the oil circuits of the two are not connected. When the lower surface of the valve core separates from the upper surface of the valve seat, the one-way device is in the open state, connecting the upper cavity and the lower cavity, and the oil circuits of the two are connected.

4. The linear oil pump according to claim 3, characterized in that, A gap a is left between the central through hole I and the pump rod, a gap b is left between the outer circumferential surface of the valve core and the inner circumferential surface of the pump body, and an O-ring seal is provided between the circumferential surfaces of the valve core and the pump rod to prevent oil from flowing out of the central through hole II. When the lower surface of the valve core is in contact with the upper surface of the valve seat, gap a and gap b are not connected. When the lower surface of the valve core separates from the upper surface of the valve seat, gap a and gap b are connected, and the oil in the lower cavity enters the upper cavity through the one-way device and is pumped out from the oil outlet.

5. The linear oil pump according to claim 4, characterized in that, The valve core is composed of a base with a frustum-shaped lower part and a top seat with a petal-shaped upper part. The outer diameter of the widest part of the bottom of the base is smaller than the inner diameter of the pump body, thus forming the gap b. The top seat has multiple protrusions evenly spaced along the circumference. Each protrusion contacts the inner circumferential surface of the pump body and guides the movement of the one-way device. The oil flows through the gap c between two adjacent protrusions. When the one-way device moves upward, it is limited by the steps set on the inner circumferential surface of the pump body.

6. The linear oil pump according to claim 1, characterized in that, The piston assembly includes: A cover plate is fitted onto the bottom of the pump rod, and the cover plate can move within a preset range along the pump rod axis; A piston is fitted onto the bottom of the pump rod and located below the cover plate. The piston is fixed to the pump rod by fasteners, and an oil passage is provided between the piston and the pump rod. The inlet of the oil passage is located on the bottom end face or outer circumferential surface of the pump rod below the piston, and the outlet of the oil passage is located on the upper surface of the piston in contact with the cover plate. The fit between the cover plate and the piston is as follows: When the lower surface of the cover plate is in contact with the upper surface of the piston, the piston assembly is in a closed state, and the flow of oil from the bottom of the piston assembly into the lower cavity is cut off by blocking the oil passage. When the lower surface of the cover plate separates from the upper surface of the piston, the piston assembly is in the open state, and the oil passage below the piston assembly is opened to allow the oil to flow into the lower cavity.

7. The linear oil pump according to claim 6, characterized in that, The bottom outer circumferential surface of the pump rod is provided with external threads, step I, and step II at intervals from bottom to top. The piston is fitted onto the pump rod between the external threads and step I. The fastener is a lock nut, which is tightened onto the external threads of the pump rod, pressing the upper surface of the piston against step I. The cover plate is fitted onto the pump rod between step I and step II, and the thickness of the cover plate is less than the distance between step I and step II. When the cover plate moves upward, it is limited by step II. The outer diameter of the cover plate is smaller than the inner diameter of the pump body, thus forming the gap d.

8. The linear oil pump according to claim 6, characterized in that, The inlet of the oil passage is located on the bottom end face of the pump rod along the axial direction, and the oil passage has multiple outlets, which are located on the upper surface of the piston and distributed circumferentially at intervals; the oil passage is implemented in the following manner: Oil passage a extends vertically upward from the inlet, and multiple oil passages b extend horizontally outward into the piston. Multiple oil passages c extend vertically upward from each oil passage b to the piston outlet.

9. The linear oil pump according to claim 1, characterized in that, The pump body is a two-section assembled structure, consisting of pump body I and pump body II connected together; the bottom of the one-way device is fixed to the connection point of the pump body, and the part of the pump body below the connection point is completely immersed in the oil. The bottom of the pump body in the axial direction is set as an open end, and multiple through holes are provided on the radial circumferential surface of the pump body near the open end. The open end and the multiple through holes together form the oil suction port.

10. A method for operating a linear oil pump according to any one of claims 1 to 9, characterized in that: When the pump rod extends, the outer diameter d1 of the piston assembly is greater than the outer diameter d2 of the pump rod inserted into the guide device. The valve core and valve seat in the one-way device separate. At this time, the one-way device is in the open state, and the upper cavity and the lower cavity are connected. The volume of the entire pump body cavity becomes smaller and the pressure increases. The lower surface of the cover plate in the piston assembly is in contact with the upper surface of the piston. At this time, the piston assembly is in the closed state. By blocking the oil passage in the piston assembly, the channel for the oil below the piston assembly to flow into the lower cavity is cut off. The oil in the lower cavity enters the upper cavity after passing through the gap between the valve seat and the pump rod, the gap between the valve core and the valve seat, and the gap between the valve core and the pump rod in sequence, and is pumped out from the oil outlet. When the pump rod retracts, the outer diameter d2 of the pump rod inserted into the guide device is greater than the outer diameter d3 of the pump rod inserted into the one-way device. The volume of the upper cavity decreases and the pressure increases. The lower surface of the valve core in the one-way device is in contact with the upper surface of the valve seat. At this time, the one-way device is in a closed state, and the upper cavity is isolated from the lower cavity. The oil in the upper cavity is pumped out from the oil outlet. The volume of the lower cavity increases and the pressure decreases. The lower surface of the cover plate in the piston assembly separates from the upper surface of the piston. The oil below the piston assembly passes through the oil passage between the piston and the pump rod, the gap between the cover plate and the piston, and the gap between the cover plate and the pump body in sequence to replenish the lower cavity, preventing vacuum cavitation.

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