Sliding surface sealing valve and plunger oil well pump adopting same

Abstract

The sliding surface sealing valve comprises a valve body outer pipe and an oil inlet base, an oil inlet is formed in the bottom of the oil inlet base, and the lower end of the valve body outer pipe is fixedly connected with the upper portion of the oil inlet base; a valve body inner pipe is arranged in a cavity of the valve body outer pipe, the lower end of the valve body inner pipe is arranged on the upper portion of the oil inlet base, and a blocking cap is arranged at the upper end of the valve body inner pipe. A sliding column is arranged in a valve body inner pipe cavity in a sliding mode, the outer wall of the sliding column is in clearance fit with the inner wall of the valve body inner pipe, and a communicating hole and an oil outlet hole are formed in the side walls of the upper end and the lower end of the valve body inner pipe respectively. And the upper end part of the sliding column is a frustum. According to the plunger oil well pump, the surface sealing traveling valve and the surface sealing fixed valve which are made of sliding surface sealing valves are adopted, traditional valve balls and valve seats are omitted, the machining difficulty and the machining cost are reduced, and the sealing reliability is improved; the oil-gas well pump is suitable for being used in oil-gas wells with various well conditions such as corrosion, sand containing and deep pumping, and the service life is effectively prolonged.

Description

Technical Field

[0001] This invention relates to an improvement of a plunger pump for oil and gas well production, as well as a traveling valve and a fixed valve, specifically a sliding surface sealing valve and a plunger pump using the sliding surface sealing valve. Background Technology

[0002] In oil and gas field development, plunger pumps are one of the main lifting devices. Traditional plunger pumps consist of a pump barrel assembly and a plunger assembly. The plunger assembly is housed within the pump barrel assembly cavity. The upper end of the pump barrel assembly is fixedly connected to the lower end of the tubing, and the upper end of the plunger assembly is fixedly connected to the lower end of the sucker rod. The pump barrel assembly includes a pump barrel, a fixed valve coupling, a fixed valve, and a tubing coupling. The plunger assembly includes a plunger, an oil outlet valve cover, and a traveling valve. The plunger and pump barrel work with a clearance fit. Currently, both the fixed valve and the traveling valve have a valve ball and valve seat structure. The valve ball and valve seat form a line seal to control the opening and closing of the oil inlet channels of the pump barrel and plunger. However, this design has drawbacks: in corrosive, sand-bearing, or deep-pumping oil and gas wells, the seal line between the valve ball and valve seat is easily damaged, causing seal failure; furthermore, the materials used for the valve ball and valve seat are very special, resulting in high manufacturing costs. Summary of the Invention

[0003] One objective of this invention is to provide a sliding surface sealing valve suitable for use in oil and gas wells under various well conditions such as corrosion, sand, and deep pumping. This valve employs a sliding surface sealing method to improve sealing reliability, extend service life, and features a simple structure and reduced manufacturing costs.

[0004] To achieve the above objectives, the technical solution adopted by this invention is as follows: A sliding surface sealing valve includes an outer valve tube and an oil inlet base. The oil inlet base has an oil inlet at its bottom center. The lower end of the outer valve tube is threadedly connected and fixed to the upper outer wall of the oil inlet base. An upper connector is fixedly provided on the upper part of the outer valve tube. The valve body is characterized by having an inner valve tube within the cavity of the outer valve tube. The lower end of the inner valve tube is inserted into and fixedly positioned within the upper cavity of the oil inlet base. A stop cap is fixedly provided at the upper end of the inner valve tube. The inner diameter of the oil inlet is smaller than the inner diameter of the inner valve tube. A sliding surface sealing valve is provided within the cavity of the inner valve tube. The valve body has a sliding column with a clearance fit between its outer wall and the inner wall of the valve body tube. A connecting hole is provided on the upper side wall of the valve body tube located below the baffle cap, and an oil outlet hole is provided on the lower side wall of the valve body tube located above the oil inlet base. The length of the sliding column is the distance between the lower end face of the baffle cap and the upper edge of the oil outlet hole. The lower end face of the sliding column is adapted to the upper edge of the oil inlet. The upper end of the sliding column is a truncated cone, the top surface of which is flush with the lower end face of the baffle cap. The bottom surface of the truncated cone is located below the connecting hole, and the base angle of the truncated cone is less than or equal to 45°.

[0005] The connecting holes are evenly distributed in 2-6 locations on the circumference of the valve body tube; the oil outlet holes are evenly distributed in 2-6 locations on the circumference of the valve body tube.

[0006] The outer wall of the slide column is provided with a wear-resistant and corrosion-resistant layer, and the inner wall of the valve body tube that matches it is provided with a wear-resistant and corrosion-resistant layer.

[0007] The baffle cap is fixed to the valve body tube by a threaded connection, and the lower outer wall of the valve body tube is fixed to the upper cavity inner wall of the oil inlet base by a threaded connection; the outer wall of the outer tube connector is provided with an external thread.

[0008] Another objective of this invention is to provide a plunger pump with a sliding surface sealing valve suitable for use in oil and gas wells under various well conditions such as corrosion, sand, and deep pumping. This pump employs a sliding surface sealing valve to create a surface-sealed moving valve and a surface-sealed fixed valve, thereby improving sealing reliability, reducing manufacturing costs, and extending service life.

[0009] To achieve the above objectives, the technical solution adopted by this invention is as follows: This is a plunger oil pump employing a sliding surface sealing valve, comprising a pump barrel assembly and a plunger assembly. The plunger assembly is disposed within the cavity of the pump barrel assembly. The upper end of the pump barrel assembly is fixedly connected to the lower end of the oil pipe, and the upper end of the plunger assembly is fixedly connected to the lower end of the sucker rod. Its characteristic is that: The pump assembly consists of an oil pipe coupling, an upper connecting pipe, an upper coupling, a pump barrel, a lower coupling, a lower connecting pipe, a fixed valve coupling, and a face-sealed fixed valve. The upper end of the upper connecting pipe is connected and fixed to the oil pipe coupling, and the lower end of the upper connecting pipe is connected and fixed to the upper end of the pump barrel through the upper coupling. The lower end of the pump barrel is connected and fixed to the upper end of the lower connecting pipe through the lower coupling. The lower end of the lower connecting pipe is connected and fixed to the upper end of the face-sealed fixed valve through the fixed valve coupling. The inner cavity of the fixed valve coupling is connected to the inner cavity of the face-sealed fixed valve. The plunger assembly consists of an oil outlet valve cover, a plunger, and a face-sealed traveling valve. The inner wall of the pump barrel is clearance-fitted with the outer wall of the plunger. An oil outlet channel is provided on the side wall of the oil outlet valve cover. The upper end of the plunger is connected and fixed to the lower end of the oil outlet valve cover. The oil outlet channel is connected to the inner cavity of the plunger. The lower end of the plunger is connected and fixed to the upper end of the face-sealed traveling valve. The inner cavity of the plunger is connected to the inner cavity of the face-sealed traveling valve. The surface-sealed fixed valve and the surface-sealed traveling valve have the same structure and are both made of sliding surface-sealed valves; The sliding surface sealing valve includes an outer valve tube and an oil inlet base. An oil inlet is located at the center of the bottom of the oil inlet base. The lower end of the outer valve tube is threaded and fixed to the upper outer wall of the oil inlet base. An upper connector is fixedly installed on the upper part of the outer valve tube. An inner valve tube is located inside the cavity of the outer valve tube. The lower end of the inner valve tube is inserted into and fixedly installed in the upper cavity of the oil inlet base. A stop cap is fixedly installed at the upper end of the inner valve tube. The inner diameter of the oil inlet is smaller than the inner diameter of the inner valve tube. A sliding column is slidably installed inside the cavity of the inner valve tube. The outer wall of the sliding column is clearance-fitted with the inner wall of the valve body tube. A connecting hole is provided on the upper side wall of the valve body tube located below the baffle cap, and an oil outlet hole is provided on the lower side wall of the valve body tube located above the oil inlet base. The length of the sliding column is the distance between the lower end face of the baffle cap and the upper edge of the oil outlet hole. The lower end face of the sliding column is adapted to the upper edge of the oil inlet. The upper end of the sliding column is a truncated cone. The top surface of the truncated cone is flush with the lower end face of the baffle cap. The bottom surface of the truncated cone is located below the connecting hole, and the base angle of the truncated cone is less than or equal to 45°.

[0010] The connecting holes are evenly distributed in 2-6 locations on the circumference of the valve body tube; the oil outlet holes are evenly distributed in 2-6 locations on the circumference of the valve body tube.

[0011] The outer wall of the slide column is provided with a wear-resistant and corrosion-resistant layer, and the inner wall of the valve body tube that matches it is provided with a wear-resistant and corrosion-resistant layer.

[0012] The baffle cap is fixed to the valve body tube by a threaded connection, and the lower outer wall of the valve body tube is fixed to the upper cavity inner wall of the oil inlet base by a threaded connection; the outer wall of the outer tube connector is provided with an external thread.

[0013] The beneficial effects of this invention are as follows: the surface-sealed traveling valve and the surface-sealed fixed valve made by using a sliding surface-sealed valve eliminate the need for traditional fixed valves and traveling valves, that is, the valve ball and valve seat are eliminated, reducing the processing difficulty and processing cost, and improving the reliability of the seal; it is suitable for use in oil and gas wells with various well conditions such as corrosion, sand, and deep pumping, effectively extending the service life, reducing the cost of equipment pump inspection and operation, and improving the economic benefits of oil production operations. Attached Figure Description

[0014] Figure 1 This is a cross-sectional schematic diagram of the plunger oil pump with a sliding surface sealing valve according to the present invention. Figure 2 This is a schematic cross-sectional view of the pump cylinder assembly of the present invention; Figure 3 This is an enlarged cross-sectional view of the plunger assembly of the present invention; Figure 4 This is an enlarged cross-sectional view of the sliding surface sealing valve of the present invention when it is closed; Figure 5This is an enlarged cross-sectional view of the sliding surface sealing valve of the present invention when it is open.

[0015] In the diagram: 1. Oil pipe coupling; 2. Upper connecting pipe; 3. Oil outlet valve cover; 31. Oil outlet flow channel; 4. Upper coupling; 5. Pump barrel; 6. Plunger; 7. Lower coupling; 8. Face-sealed traveling valve; 9. Face-sealed fixed valve; 10. Lower connecting pipe; 11. Fixed valve coupling; 12. Valve body outer pipe; 121. Upper connector of outer pipe; 13. Stop cap; 14. Valve body inner pipe; 141. Connecting hole; 142. Oil outlet hole; 15. Sliding column; 151. Cone; 16. Oil inlet base; 161. Oil inlet. Detailed Implementation

[0016] Reference Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 This invention is made.

[0017] This sliding surface sealing valve includes an outer valve tube 12 and an oil inlet base 16. The oil inlet base 16 has an oil inlet 161 at its bottom center. The lower end of the outer valve tube 12 is threadedly connected to the upper outer wall of the oil inlet base 16. An upper connector 121 is fixedly provided on the upper part of the outer valve tube 12. The valve body 14 is located inside the cavity of the outer valve tube 12. The lower end of the valve body 14 is inserted into and fixedly positioned in the upper cavity of the oil inlet base 16. A stop cap 13 is fixedly provided at the upper end of the valve body 14. The inner diameter of the oil inlet 161 is smaller than the inner diameter of the valve body 14. A sliding column 15 is slidably provided inside the cavity of the valve body 14. The outer wall of the sliding column 15 is clearance-fitted with the inner wall of the valve body 14, forming a large-area surface seal between them. A connecting hole 141 is provided on the upper side wall of the valve body 14 below the stop cap 13. An oil outlet 142 is provided on the lower end side wall of the valve body tube 14 above the oil inlet base 16. The length of the slide rod 15 is the distance between the lower end face of the stop cap 13 and the upper edge of the oil outlet 142. The lower end face of the slide rod 15 is adapted to the upper edge of the oil inlet 161. Since the inner diameter of the oil inlet 161 is smaller than the inner diameter of the valve body tube 14, and the outer diameter of the slide rod 15 is the same as the inner diameter of the valve body tube 14, the inner diameter of the oil inlet 161 is smaller than the outer diameter of the slide rod 15. The slide column 15 slides down until it lands on the upper edge of the oil inlet 161. The upper end of the slide column 15 is a truncated cone 151. The top surface of the truncated cone 151 is flush with the lower end surface of the stop cap 13. The bottom surface of the truncated cone 151 is located below the connecting hole 141. Furthermore, the bottom angle of the truncated cone 151 is less than or equal to 45°. In this way, when the slide column 15 falls, the oil can form a thrust on the side wall of the truncated cone 15, allowing the slide column 15 to slide down quickly.

[0018] The connecting holes 141 are evenly distributed in 2-6 locations on the circumference of the valve body tube 14; the oil outlet holes 142 are evenly distributed in 2-6 locations on the circumference of the valve body tube 14.

[0019] The outer wall of the slide column 15 is provided with a wear-resistant and corrosion-resistant layer, and the inner wall of the valve body tube 14 that matches it is provided with a wear-resistant and corrosion-resistant layer, thereby improving the wear-resistant and corrosion-resistant performance of the slide column 15 and the valve body tube 14 during long-term operation and extending their service life. The manufacturing method of the wear-resistant and corrosion-resistant layer is existing technology, so it will not be described in detail.

[0020] The cap 13 is fixed to the valve body tube 14 by a threaded connection. The lower outer wall of the valve body tube 14 is fixed to the upper cavity inner wall of the oil inlet base 16 by a threaded connection to facilitate assembly. The outer wall of the upper connector 121 of the outer tube is provided with an external thread.

[0021] This is a plunger oil pump employing a sliding surface sealing valve, comprising a pump barrel assembly and a plunger assembly. The plunger assembly is disposed within the cavity of the pump barrel assembly. The upper end of the pump barrel assembly is fixedly connected to the lower end of the oil pipe, and the upper end of the plunger assembly is fixedly connected to the lower end of the sucker rod. Its characteristic is that: The pump assembly consists of an oil pipe coupling 1, an upper connecting pipe 2, an upper coupling 4, a pump barrel 5, a lower coupling 7, a lower connecting pipe 10, a fixed valve coupling 11, and a face-sealing fixed valve 9. The upper end of the upper connecting pipe 2 is connected and fixed to the oil pipe coupling 1. The lower end of the upper connecting pipe 2 is connected and fixed to the upper end of the pump barrel 5 through the upper coupling 4. The lower end of the pump barrel 5 is connected and fixed to the upper end of the lower connecting pipe 10 through the lower coupling 7. The lower end of the lower connecting pipe 10 is connected and fixed to the upper end of the face-sealing fixed valve 9 through the fixed valve coupling 11. The inner cavity of the fixed valve coupling 11 is connected to the inner cavity of the face-sealing fixed valve 9. The plunger assembly consists of an oil outlet valve cover 3, a plunger 6, and a face-sealed traveling valve 8. The inner wall of the pump barrel 5 is clearance-fitted with the outer wall of the plunger 6. An oil outlet channel 31 is provided on the side wall of the oil outlet valve cover 3. The upper end of the plunger 6 is connected and fixed to the lower end of the oil outlet valve cover 3. The oil outlet channel 31 is connected to the inner cavity of the plunger 6. The lower end of the plunger 6 is connected and fixed to the upper end of the face-sealed traveling valve 8. The inner cavity of the plunger 6 is connected to the inner cavity of the face-sealed traveling valve 8. The surface-sealed fixed valve 9 and the surface-sealed traveling valve 8 have the same structure and are both made of sliding surface-sealed valves; The sliding surface sealing valve includes an outer valve tube 12 and an oil inlet base 16. An oil inlet 161 is located at the center of the bottom of the oil inlet base 16. The lower end of the outer valve tube 12 is threadedly connected to the upper outer wall of the oil inlet base 16. An upper connector 121 is fixedly installed on the upper part of the outer valve tube 12. An inner valve tube 14 is located inside the cavity of the outer valve tube 12. The lower end of the inner valve tube 14 is inserted into and fixedly installed in the upper cavity of the oil inlet base 16. A stop cap 13 is fixedly installed at the upper end of the inner valve tube 14. The inner diameter of the oil inlet 161 is smaller than the inner diameter of the inner valve tube 14. A sliding column 15 is slidably installed inside the cavity of the inner valve tube 14. The outer wall of the valve body is clearance-fitted with the inner wall of the valve body tube 14. A connecting hole 141 is provided on the upper side wall of the valve body tube 14 located below the baffle cap 13. An oil outlet hole 142 is provided on the lower side wall of the valve body tube 14 located above the oil inlet base 16. The length of the sliding column 15 is the distance between the lower end face of the baffle cap 13 and the upper edge of the oil outlet hole 142. The lower end face of the sliding column 15 is adapted to the upper edge of the oil inlet 161. The upper end of the sliding column 15 is a truncated cone 151. The top surface of the truncated cone 151 is flush with the lower end face of the baffle cap 13. The bottom surface of the truncated cone 151 is located below the connecting hole 141. Furthermore, the bottom angle of the truncated cone 151 is less than or equal to 45°.

[0022] The connecting holes 141 are evenly distributed in 2-6 locations on the circumference of the valve body tube 14; the oil outlet holes 142 are evenly distributed in 2-6 locations on the circumference of the valve body tube 14.

[0023] The outer wall of the sliding column 15 is provided with a wear-resistant and corrosion-resistant layer, and the inner wall of the valve body tube 14 that matches it is provided with a wear-resistant and corrosion-resistant layer.

[0024] The stop cap 13 is fixed to the valve body tube 14 by a threaded connection, and the lower outer wall of the valve body tube 14 is fixed to the upper cavity inner wall of the oil inlet base 16 by a threaded connection; the outer wall of the outer tube upper connector 121 is provided with an external thread.

[0025] When using this invention for oil well operations, the tubing coupling 1 of the pump assembly is connected and fixed to the lower end of the tubing, and the oil outlet valve cover 3 of the plunger assembly is connected and fixed to the lower end of the sucker rod.

[0026] During the upstroke, the sucker rod lifts the plunger assembly. Under the pressure of its own weight and the oil pressure exerted on the side of the cone 151 by the oil in the plunger 6 cavity through the connecting hole 141, the slide 15 of the face-sealed traveling valve 8 of the plunger assembly rapidly slides down and seals the oil inlet 142 until the lower end of the slide 15 lands on the oil inlet 161, at which point the face-sealed traveling valve 8 closes. At this time, a negative pressure is formed above the face-sealed fixed valve 9 of the pump assembly. Because the inner cavity of the valve body tube 14 is connected through the connecting hole 141... 41 is connected to the inner cavity of the outer tube 12 of the valve body. The cavity of the inner tube 14 of the valve body above the sliding column 15 is also under negative pressure. The oil in the well pushes the sliding column 15 upward from the oil inlet 161, so that the sliding column 15 moves upward until the cone 151 on the upper part of the sliding column 15 reaches the stop cap 13, thereby opening the oil outlet 142. The oil flows from the oil outlet 142 into the cavity of the outer tube 12 of the valve body and enters the cavity of the lower connecting pipe 10 below the plunger assembly; thereby achieving the purpose of oil extraction. During the downstroke, the sucker rod pushes the plunger assembly downwards, increasing the oil pressure in the lower connecting pipe 10 below the plunger assembly. The oil, through the connecting hole 141 of the face seal fixed valve 9, exerts a thrust on the cone 151 above the slide column 15. Combined with the weight of the slide column 15 itself, the slide column 15 slides down rapidly and closes the oil outlet 142 until it lands on the oil inlet 161, thus closing the face seal fixed valve 9. At the same time, the oil below the face seal traveling valve 8 enters through the oil inlet 161 of the face seal traveling valve 8 and pushes the slide column 15 upwards until it opens the oil outlet 142. The oil enters the outer tube 12 of the valve body of the face seal traveling valve 8, then flows into the plunger 6 chamber, and finally flows into the upper connecting pipe 2 chamber from the oil outlet channel 31 of the oil outlet valve cover 3, achieving the purpose of oil discharge and lifting to the ground.

Claims

1. A sliding surface sealing valve, comprising an outer valve body tube (12) and an oil inlet base (16), wherein an oil inlet (161) is provided at the bottom center of the oil inlet base (16), the lower end of the outer valve body tube (12) is threadedly connected and fixed to the upper outer wall of the oil inlet base (16), and an upper connector (121) is fixedly provided on the upper part of the outer valve body tube (12); characterized in that: The valve body tube (14) is provided inside the cavity of the valve body tube (12). The lower end of the valve body tube (14) is inserted into and fixedly installed in the upper cavity of the oil inlet base (16). The upper port of the valve body tube (14) is fixedly provided with a stop cap (13). The inner diameter of the oil inlet (161) is smaller than the inner diameter of the valve body tube (14). The valve body tube (14) is slidably provided with a sliding column (15) inside the cavity. The outer wall of the sliding column (15) is clearance-fitted with the inner wall of the valve body tube (14). A connecting hole (141) is provided on the upper side wall of the valve body tube (14) located below the stop cap (13). An oil outlet (142) is provided on the lower side wall of the valve body tube (14) located above the oil inlet base (16). The length of the slide column (15) is the distance between the lower end face of the stop cap (13) and the upper edge of the oil outlet (142). The lower end face of the slide column (15) is adapted to the upper edge of the oil inlet (161). The upper end of the slide column (15) is a truncated cone (151). The top surface of the truncated cone (151) is flush with the lower end face of the stop cap (13). The bottom surface of the truncated cone (151) is located below the connecting hole (141). Furthermore, the bottom angle of the truncated cone (151) is less than or equal to 45°.

2. A sliding surface sealing valve according to claim 1, characterized in that: The connecting holes (141) are evenly distributed in 2-6 locations on the circumference of the valve body tube (14); the oil outlet holes (142) are evenly distributed in 2-6 locations on the circumference of the valve body tube (14).

3. A sliding surface sealing valve according to claim 1, characterized in that: The outer wall of the slide column (15) is provided with a wear-resistant and corrosion-resistant layer, and the inner wall of the valve body tube (14) that matches it is provided with a wear-resistant and corrosion-resistant layer.

4. A sliding surface sealing valve according to claim 1, characterized in that: The stop cap (13) is fixed to the valve body tube (14) by a threaded connection. The lower outer wall of the valve body tube (14) is fixed to the upper cavity inner wall of the oil inlet base (16) by a threaded connection. The outer wall of the outer tube connector (121) is provided with an external thread.

5. A plunger oil pump employing the sliding surface sealing valve of claim 1, comprising a pump barrel assembly and a plunger assembly, the plunger assembly being disposed within the cavity of the pump barrel assembly, the upper end of the pump barrel assembly being fixedly connected to the lower end of the oil pipe, and the upper end of the plunger assembly being fixedly connected to the lower end of the sucker rod; characterized in that: The pump assembly consists of an oil pipe coupling (1), an upper connecting pipe (2), an upper coupling (4), a pump barrel (5), a lower coupling (7), a lower connecting pipe (10), a fixed valve coupling (11), and a face-sealed fixed valve (9). The upper end of the upper connecting pipe (2) is connected and fixed to the oil pipe coupling (1). The lower end of the upper connecting pipe (2) is connected and fixed to the upper end of the pump barrel (5) through the upper coupling (4). The lower end of the pump barrel (5) is connected and fixed to the upper end of the lower connecting pipe (10) through the lower coupling (7). The lower end of the lower connecting pipe (10) is connected and fixed to the upper end of the face-sealed fixed valve (9) through the fixed valve coupling (11). The inner cavity of the fixed valve coupling (11) is connected to the inner cavity of the face-sealed fixed valve (9). The plunger assembly consists of an oil outlet valve cover (3), a plunger (6), and a face-sealed traveling valve (8). The inner wall of the pump barrel (5) is clearance-fitted with the outer wall of the plunger (6). An oil outlet channel (31) is provided on the side wall of the oil outlet valve cover (3). The upper end of the plunger (6) is connected and fixed to the lower end of the oil outlet valve cover (3). The oil outlet channel (31) is connected to the inner cavity of the plunger (6). The lower end of the plunger (6) is connected and fixed to the upper end of the face-sealed traveling valve (8). The inner cavity of the plunger (6) is connected to the inner cavity of the face-sealed traveling valve (8). The surface-sealed fixed valve (9) and the surface-sealed moving valve (8) have the same structure and are both made of sliding surface-sealed valves; The sliding surface sealing valve includes an outer valve tube (12) and an oil inlet base (16). The oil inlet base (16) has an oil inlet (161) at its bottom center. The lower end of the outer valve tube (12) is threadedly connected to the upper outer wall of the oil inlet base (16). An upper connector (121) is fixedly provided on the upper part of the outer valve tube (12). An inner valve tube (14) is provided inside the cavity of the outer valve tube (12). The lower end of the inner valve tube (14) is inserted into and fixedly installed in the upper cavity of the oil inlet base (16). A stop cap (13) is fixedly provided on the upper end of the inner valve tube (14). The inner diameter of the oil inlet (161) is smaller than the inner diameter of the inner valve tube (14). A sliding column (15) is slidably provided inside the cavity of the inner valve tube (14). The outer wall of the valve body is fitted with the inner wall of the valve body tube (14) with clearance. A connecting hole (141) is provided on the upper side wall of the valve body tube (14) located below the baffle cap (13). An oil outlet hole (142) is provided on the lower side wall of the valve body tube (14) located above the oil inlet base (16). The length of the slide column (15) is the distance between the lower end face of the baffle cap (13) and the upper edge of the oil outlet hole (142). The lower end face of the slide column (15) is adapted to the upper edge of the oil inlet (161). The upper end of the slide column (15) is a truncated cone (151). The top surface of the truncated cone (151) is flush with the lower end face of the baffle cap (13). The bottom surface of the truncated cone (151) is located below the connecting hole (141). The bottom angle of the truncated cone (151) is less than or equal to 45°.

6. A plunger oil pump employing a sliding surface sealing valve according to claim 5, characterized in that: The connecting holes (141) are evenly distributed in 2-6 locations on the circumference of the valve body tube (14); the oil outlet holes (142) are evenly distributed in 2-6 locations on the circumference of the valve body tube (14).

7. A plunger oil pump employing a sliding surface sealing valve according to claim 5, characterized in that: The outer wall of the slide column (15) is provided with a wear-resistant and corrosion-resistant layer, and the inner wall of the valve body tube (14) that matches it is provided with a wear-resistant and corrosion-resistant layer.

8. A plunger oil pump employing a sliding surface sealing valve according to claim 5, characterized in that: The stop cap (13) is fixed to the valve body tube (14) by a threaded connection. The lower outer wall of the valve body tube (14) is fixed to the upper cavity inner wall of the oil inlet base (16) by a threaded connection. The outer wall of the outer tube connector (121) is provided with an external thread.

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