Pressure Controller

Abstract

The purpose of the present invention is to provide a pressure controller capable of adjusting the fuel pressure in the negative zone of the venturi tube, comprising a mounting plate for connecting a pump oil pipe, the venturi tube passing through a central hole opened in the middle of the mounting plate and forming an axial limit fit, the inner cavity of the venturi tube forming a main fuel passage and the narrowest position of the main fuel passage forming a negative zone of the venturi tube, a through hole penetrating the disk surface is opened on the mounting plate surface located inside the pump oil pipe, and an adjusting unit adjusts the cross-sectional area of ​​the through hole to adjust the fuel pressure in the negative zone of the venturi tube. For the venturi tube, the flow rate in the negative zone increases and the pressure decreases, and the flow rate decreases and the pressure increases. In the above scheme, by adjusting the cross-sectional area of ​​the through hole, the fuel flow rate flowing through the through hole is changed, and the flow rate flowing through the main fuel passage is indirectly changed, so that the fuel pressure at the fuel inlet of the aircraft fuel tank is always equal to the fuel pressure in the negative zone of the venturi tube, thereby achieving the purpose of controlling the fuel pressure at the fuel inlet of the aircraft fuel tank.

Description

Technical Field

[0001] The invention relates to the technical field of aviation refueling equipment, and specifically designs a pressure controller used in an aircraft refueling vehicle. Background Art

[0002] Aircraft refueling trucks are the most widely used refueling equipment at large and medium-sized airports, and they play a great role in aircraft refueling security. When refueling an aircraft, it is required to be fast, safe and with a large flow rate, so it is hoped that the working pressure of the aircraft refueling truck's oil pump system is as high as possible, but the pressure value that the aircraft fuel tank and its internal fuel supply system can withstand is certain. Excessive pressure will cause damage to the aircraft fuel tank and its internal fuel supply system. This requires the aircraft refueling truck to be equipped with a pressure control system to automatically control the fuel pressure at the aircraft fuel tank inlet so that it does not exceed the allowable value.

[0003] The pressure control principle of aircraft refueling truck is as follows Figure 1 As shown, a pressure circuit consisting of a venturi tube 2 and a pressure control valve 1 is set in the refueling system. When refueling an aircraft, fuel is injected into the aircraft fuel tank 4 through the refueling hose 3. It is difficult to directly collect the fuel pressure signal from the end of the refueling hose 3, that is, the fuel inlet of the aircraft fuel tank 4, and then feed the signal back to the pressure control valve 1 for pressure control. For this reason, a venturi tube 2 is set in the pumping system. The venturi tube 2 is also called the Venturi tube. It achieves the effect of increasing the flow rate and reducing the pressure by narrowing its cross section. The narrowest cross section of the venturi tube is usually called the negative area of ​​the venturi tube. The appropriate diameter of the negative area of ​​the venturi tube is determined by calculation, so that the fuel pressure at the fuel inlet of the fuel tank is always equal to the fuel pressure in the negative area of ​​the venturi tube 2. In this way, we can use the fuel pressure in the negative area of ​​the venturi tube 2 to simulate the fuel pressure at the fuel inlet of the fuel tank. The negative area interface of the venturi tube 2 is connected to the hydraulic control interface A of the pressure control valve 1, so that the switch of the pressure control valve 1 can be controlled by the fuel pressure in the negative area of ​​the venturi tube 2, that is, the fuel pressure at the fuel inlet of the fuel tank. When refueling an aircraft, when the fuel pressure at the fuel inlet of the fuel tank is lower than the allowable value, and the sum of the pressure in the negative area of ​​the venturi tube 2 and the pressure of the balancing spring is lower than the air control pressure (the air control pressure value is the sum of the allowable value of the fuel pressure in the aircraft fuel tank and the force of the balancing spring), the pressure control valve 1 is in the open position, the fuel can pass through the pressure control valve 1, and the oil pumping system is in the refueling state; conversely, when the pressure at the fuel inlet of the aircraft fuel tank is higher than the allowable value, the sum of the pressure in the negative area of ​​the venturi tube 2 and the pressure of the balancing spring is higher than the air control pressure, the pressure control valve 1 is closed, the fuel cannot pass through the pressure control valve 1, and the oil pumping system stops refueling, thereby realizing automatic pressure control. Summary of the invention

[0004] The object of the present invention is to provide a pressure controller capable of adjusting the fuel pressure in the negative zone of a venturi.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a pressure controller, including a mounting plate for connecting a pump oil pipe, the venturi tube passes through a central hole opened in the middle of the mounting plate and forms an axial limit fit, the inner cavity of the venturi tube forms a main fuel passage and the narrowest position of the main fuel passage forms a negative zone of the venturi tube, a through hole penetrating the disk surface is opened on the mounting plate surface located inside the pump oil pipe, and the adjustment unit adjusts the cross-sectional area of ​​the through hole to adjust the fuel pressure in the negative zone of the venturi tube.

[0006] In the above scheme, for the venturi tube, the flow velocity in the negative zone increases and the pressure decreases, and the flow velocity decreases and the pressure increases. Therefore, by adjusting the cross-sectional area of ​​the through hole, the fuel flow rate flowing through the through hole is changed, and the flow rate flowing through the main fuel passage is indirectly changed, so that the fuel pressure at the fuel inlet of the aircraft fuel tank is always equal to the fuel pressure in the negative zone of the venturi tube, thereby achieving the purpose of controlling the fuel pressure at the fuel inlet of the aircraft fuel tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is the pressure control schematic diagram of the aircraft refueling truck;

[0008] Figure 2 It is the overall structural diagram of the pressure controller;

[0009] Figure 3 for Figure 2 Exploded view of;

[0010] Figure 4 It is a schematic diagram of the fuel auxiliary passage B of the pressure controller in the fully closed state;

[0011] Figure 5 It is a schematic diagram of the fuel auxiliary passage B of the pressure controller in a half-open state;

[0012] Figure 6 It is a schematic diagram of the fuel auxiliary passage B of the pressure controller in the fully open state;

[0013] Figure 7 for Figure 2 A cross-sectional view of

[0014] Figure 8 It is a schematic diagram of the overall structure of the pressure controller with a second channel;

[0015] Fig. 9 for Figure 8 Schematic diagram of the fuel auxiliary passage B in a fully open state;

[0016] Fig.10 for Figure 8 sectional view of . DETAILED DESCRIPTION

[0017] Combine the following Figure 2-Figure 7 The present invention is described in further detail.

[0018] A pressure controller includes a mounting plate 10 for connecting a pump oil pipe, a venturi tube 20 passing through a center hole 11 opened in the middle of the mounting plate 10 and forming an axial limit fit, an inner cavity of the venturi tube 20 forming a main fuel passage A and the narrowest position of the main fuel passage A forming a negative zone of the venturi tube, a through hole 12 penetrating the disk surface is opened on the mounting plate 10 located inside the pump oil pipe, and an adjustment unit adjusts the cross-sectional area of ​​the through hole 12 to adjust the fuel pressure in the negative zone of the venturi tube 20.

[0019] First of all, it should be explained that the oil pump pipe (not shown in the figure) is connected to both sides of the mounting plate 10, that is, the venturi tube 20 is located in the oil pump pipe, which is a tube in a tube. A large part of the fuel passing through the oil pump pipe passes through the inner cavity of the venturi tube 20 to form the main fuel passage A, and the other part passes through the through hole 12 opened on the mounting plate 10 (the premise is that the through hole 12 allows the fuel to pass through under the adjustment of the adjustment unit. If the adjustment unit adjusts the through hole 12 to be closed, then all the fuel passing through the oil pump pipe passes through the inner cavity of the venturi tube 20 to form the main fuel passage A). For the venturi tube, the flow rate in the negative zone increases and the pressure decreases, and the flow rate decreases and the pressure increases. By adjusting the cross-sectional area of ​​the through hole 12, the fuel flow rate flowing through the through hole 12 is changed, and the flow rate flowing through the main fuel passage A is indirectly changed, so that the fuel pressure at the fuel inlet of the aircraft fuel tank is always equal to the fuel pressure in the negative zone of the venturi tube, thereby achieving the purpose of controlling the fuel pressure at the fuel inlet of the aircraft fuel tank.

[0020] As a preferred solution of the present invention, the adjustment unit includes an adjustment disk 30. An annular recess 13 is provided on the disk surface of the mounting disk 10 on the oil inlet side. The through hole 12 is provided at the bottom of the annular recess 13. The adjustment disk 30 is embedded in the annular recess 13. A circular hole 31 corresponding to the position of the through hole 12 is provided on the adjustment disk 30. The power drives the adjustment disk 30 to rotate to change the overlapping area of ​​the circular hole 31 and the through hole 12. The communicating area of ​​the circular hole 31 and the through hole 12 constitutes the fuel auxiliary passage B. By rotating the adjustment disk 30 to change the position of the circular hole 31 thereon, the overlapping area of ​​the circular hole 31 and the through hole 12 is changed accordingly. When the circular hole 31 and the through hole 12 are completely misaligned, as shown in FIG. Figure 4 As shown, the fuel auxiliary passage B is closed, and the fuel cannot pass through the fuel auxiliary passage B, and all the fuel passes through the fuel main passage A; when the circular hole 31 and the through hole 12 partially overlap, as shown Figure 5 As shown, the fuel auxiliary passage B is partially opened, a part of the fuel passes through the fuel auxiliary passage B, and the other part of the fuel passes through the fuel main passage A; when the circular hole 31 and the through hole 12 completely overlap, as shown in FIG. Figure 6As shown, the auxiliary fuel passage B is fully opened, part of the fuel passes through the auxiliary fuel passage B, and the other part of the fuel passes through the main fuel passage A. Figure 5 In general, the fuel flow rate and flow velocity of the fuel flowing through the main fuel passage A are small, and the fuel pressure in the negative area of ​​the venturi tube 20 is large. That is to say, when the auxiliary fuel passage B changes from small to large, the fuel pressure in the negative area of ​​the venturi tube 20 gradually increases; conversely, when the auxiliary fuel passage B changes from large to small, the fuel pressure in the negative area of ​​the venturi tube 20 gradually decreases; thereby, the fuel pressure in the negative area of ​​the venturi tube 20 is regulated, and the fuel pressure at the fuel inlet of the aircraft tank is controlled.

[0021] Furthermore, the annular recess 13 is arranged outside the central hole 11 and the two are arranged coaxially, and the disk surfaces on both sides of the adjusting disk 30 respectively abut against the concave bottom of the annular recess 13 and the steps arranged on the outer wall of the venturi tube 20 to form an axial limit fit. In this way, the axial position of the adjusting disk 30 is limited and can only be rotated, ensuring that the disk surface of the adjusting disk 30 fits the concave bottom of the annular recess 13.

[0022] In order to ensure that the fuel flows evenly from the outside of the venturi tube 20, it is required that the cores of the through holes 12 and the circular holes 31 are arranged in parallel with the tube core of the venturi tube 20, the diameter of the circular hole 31 is equal to the diameter of the through hole 12, a plurality of through holes 12 are evenly spaced along the circumferential direction at the bottom of the annular recess 13, and a plurality of circular holes 31 are correspondingly arranged on the regulating disk 30. The fuel passing from the outside of the main fuel passage A is evenly diverted to the downstream through the auxiliary fuel passage B formed by the plurality of through holes 12 and the circular holes 31 in the circumferential direction.

[0023] Furthermore, a guide pin 32 is provided on the disk surface of the adjustment disk 30, which protrudes toward the bottom of the annular recess 13. The guide pin 32 is inserted into the arc-shaped guide groove 14 provided on the bottom of the annular recess 13 to form a guide sliding fit, and the curvature center of the arc-shaped guide groove 14 is colinear with the disk core of the adjustment disk 30. Due to the guiding effect of the arc-shaped guide groove 14, the adjustment disk 30 always rotates around its own disk core, preventing the adjustment disk 30 from being offset, and ensuring that the hole cores of the through hole 12 and the circular hole 31 are located on the same cylindrical surface.

[0024] In order to improve the working efficiency, when the guide pin 32 is at the two ends of the arc-shaped guide groove 14 (i.e., when the fuel auxiliary passage B is in the fully open and fully closed states), the included angle between the center of the guide pin 32 and the connecting line of the core of the adjusting disk 30 is α, and the included angle between the tangents on both sides of the minimum aperture of the circular hole 31 of the core of the adjusting disk 30 (because the hole shape of the circular hole 31 is the same as the tube shape of the contraction tube section 22) is β, α = β. That is to say, when the guide pin 32 is at one end of the arc-shaped guide groove 14, the fuel auxiliary passage B is in the fully closed state, and when the guide pin 32 is rotated to the other end of the arc-shaped guide groove 14, the fuel auxiliary passage B is in the fully open state, which can prevent the adjusting disk 30 from rotating too much and affecting the next adjustment.

[0025] An adjustment hole 15 is provided on the mounting disk 10, and a bolt assembly 40 is inserted into the adjustment hole 15 from the outside of the mounting disk 10 and abuts against the adjustment disk 30. The adjustment disk 30 is pushed to rotate by rotating the bolt assembly 40. If the length direction of the adjustment hole 15 and the abutment are in line with the line connecting the core of the mounting disk 10, the adjustment disk 30 cannot be rotated. Therefore, the length direction of the adjustment hole 15 and the abutment are arranged at an angle to the line connecting the core of the mounting disk 10. The bolt assembly 40 is pushed to push the adjustment disk 30 to rotate into place and then lock it.

[0026] The specific structure is that the bolt assembly 40 includes a guide bolt 41 fixedly set in the adjustment hole 15, the guide bolt 41 is a hollow structure and an adjustment screw 42 is threadedly connected in the hollow inner cavity, the inner end of the adjustment screw 42 is against the guide column 43, and the guide pin 32 is clamped at the position between the two guide columns 43. The adjustment hole 15 includes a threaded hole section corresponding to the guide bolt 41 and a light hole section corresponding to the guide column 43. The aperture of the threaded hole section is consistent with the outer diameter of the guide bolt 41, and the aperture of the light hole section is consistent with the outer diameter of the guide column 43 to play a guiding role to ensure that the guide column 43 moves in a straight line. A missing portion 16 for accommodating the bolt head of the guide bolt 41 is opened on the mounting plate 10, and a dust cover 44 is provided at the end of the hollow inner cavity of the guide bolt 41. In order to prevent debris from entering the hollow inner cavity of the guide bolt 41 and affecting the rotation of the adjustment screw 42, a dust cover 44 is provided at the end of the hollow inner cavity. During operation, first remove the dust cover, loosen the adjusting screw 42 on one side, rotate the adjusting screw 42 on the other side to push the guide column 43 on that side to move, and the thrust of the guide column 43 pushes the guide pin 32 to rotate along the arc guide groove 14, that is, the adjusting disk 30 rotates, so that the working pressure in the negative area of ​​the Venturi tube is equal to the required working pressure, balance the other adjusting screw 42 and lock it, and finally cover the dust cover 44.

[0027] Normally, the venturi tube 20 includes a diffuser section 21 and a contraction section 22. The contraction section 22 is arranged near the oil inlet side, and the diffuser section 21 is arranged near the oil outlet side. The small diameter ends of the diffuser section 21 and the contraction section 22 are equal in diameter and arranged near each other. A gap 23 is left between the two small diameter ends. The two small diameter ends and the gap 23 together constitute the negative zone of the venturi tube. The "diffusion" and "contraction" here refer to the gradual increase or decrease in the diameter of the venturi tube along the flow direction of the fuel. That is to say, the diameter of the contraction section 22 on the oil inlet side gradually decreases, and the diameter of the diffuser section 21 on the oil outlet side gradually increases. The small diameter ends of the diffuser section 21 and the contraction section 22 are not fixedly connected, but a gap 23 is left in the middle to collect the fuel pressure in the negative zone of the venturi tube. The hole type of the circular hole 31 of the regulating plate 30 is a variable diameter shape which is the same as the tube type of the contraction tube section 22, and the hole type of the through hole 12 of the mounting plate 10 is a variable diameter shape which is the same as the tube type of the diffusion tube section 21. The inner diameter of the small diameter end of the circular hole 31 is equal to the inner diameter of the small diameter end of the through hole 12. In this way, the auxiliary fuel passage B formed by the through hole 12 and the circular hole 31 is also equivalent to a venturi tube, which reduces the resistance loss of the auxiliary fuel passage B.

[0028] Furthermore, an annular groove 111 is provided on the inner wall of the center hole 11 of the mounting plate 10, and the diffuser section 21 and the contraction section 22 are inserted from both sides of the center hole 11. The external threads on the outer walls of the diffuser section 21 and the contraction section 22 are threadedly connected with the internal threads of the center hole 11, and the steps on the outer walls of the diffuser section 21 and the contraction section 22 abut against the two ends of the center hole 11 to form an axial limit fit. The pressure collection area of ​​the negative zone of the venturi tube is located in the annular groove 111, and the mounting plate 10 is radially provided with a first channel 17 that communicates with the annular groove 111 from the outer wall, and the outer end of the first channel 17 is connected to a pipe joint connected to the pressure control valve. During installation, the diffuser section 21 and the contraction section 22 are screwed in from both sides of the center hole 11 respectively until the steps on the outer walls of the diffuser section 21 and the contraction section 22 abut against the two ends of the center hole 11, indicating that they are installed in place. The pressure collection area of ​​the negative zone of the venturi is located in the annular groove 111, and the pressure control valve is connected to the annular groove 111 through the first channel 17, that is, connected to the negative zone of the venturi. The fuel pressure in the negative zone of the venturi directly controls the on-off of the pressure control valve, thereby realizing automatic pressure control.

[0029] In order to connect with the pump oil pipe, a mounting hole 18 for connecting with the pump oil pipe is provided on the mounting plate 10 surface at the outer periphery of the mounting plate 10 in the circumferential direction, and an annular groove is also provided on the mounting plate 10 surface between the mounting hole 18 and the annular recess 13, and a sealing ring 50 is provided in the annular groove. The inner diameter of the pump oil pipe should be larger than the diameter of the circumscribed circle of the circular holes 31 distributed on the adjusting plate 30 and the diameter of the circumscribed circle of the through holes 12 distributed on the mounting plate 10, so that the circular holes 31 and the through holes 12 are exposed to the flow path of the fuel in the pump oil pipe. A mounting flange is provided at the end of the pump oil pipe, and the mounting flange is in contact with the mounting plate 10 surface. The mounting hole on the mounting flange is fixedly connected with the mounting hole 18 on the mounting plate 10 surface by bolts. In order to prevent fuel leakage, a sealing ring 50 is also provided here, and the sealing ring 50 is in contact with the pump oil pipe mounting flange to form a sealing fit.

[0030] Since it is also necessary to collect the fuel pressure in the pump oil pipe, if a collection port is directly opened on the pump oil pipe, it is necessary to destroy the original structure of the pump oil pipe and solve problems such as sealing. Therefore, a second channel 19 is also provided on the mounting disk 10, and the second channel 19 includes a radial channel 191 radially opened from the outer wall of the mounting disk 10, and an axial channel 192 is bent and extended from the inner end of the radial channel 191, and an outlet a of the axial channel 192 is arranged at the bottom position of the annular recess 13, and a part of the disk surface is cut off at the position corresponding to the outlet a of the adjusting disk 30 and the axial channel 192 to form an avoidance portion 33, and the outlet a is exposed outside the adjusting disk 30, and the outer end of the radial channel 191 is connected to a pipe joint connected to the pressure control valve. In this way, we also set the fuel pressure collection port of the pump oil pipe on the pressure controller, and there is no need to change the structure of the pump oil pipe itself. The specific method is to set the pipe joint connected to the pressure control valve on the outer disk surface of the mounting disk 10, and the outlet a of the second channel 19 is exposed to the outside of the regulating disk 30. By collecting the fuel pressure at the outlet a (called the positive zone of the Venturi tube in the industry), the fuel pressure in the pump oil pipe is obtained for flow control and pressure balance.

[0031] Furthermore, the avoidance portion 33 is arranged away from the guide pin 32 , that is, the outlet a and the arc-shaped guide groove 14 are in a relatively avoidance position.

Claims

1. A pressure controller, characterized in that: The invention comprises a mounting plate (10) for connecting an oil pump pipe, a venturi tube (20) passing through a central hole (11) provided in the middle of the mounting plate (10) and forming an axial limit fit, the inner cavity of the venturi tube (20) forming a main fuel passage A and the narrowest position of the main fuel passage A forming a negative zone of the venturi tube, a through hole (12) penetrating the surface of the mounting plate (10) located inside the oil pump pipe being provided with a regulating unit for regulating the cross-sectional area of ​​the through hole (12) for regulating the fuel pressure in the negative zone of the venturi tube (20); the regulating unit comprises a regulating plate (30), and a regulating unit (31) is provided on the surface of the mounting plate (10) on the oil inlet side thereof An annular recess (13) is provided, a through hole (12) is arranged at the bottom of the annular recess (13), an adjusting disk (30) is embedded in the annular recess (13), a circular hole (31) corresponding to the position of the through hole (12) is opened on the adjusting disk (30), the adjusting disk (30) is driven by power to rotate to change the overlapping area of ​​the circular hole (31) and the through hole (12), and the communicating area of ​​the circular hole (31) and the through hole (12) constitutes a fuel auxiliary passage B; a plurality of through holes (12) are evenly spaced at the bottom of the annular recess (13) along the circumferential direction, and a plurality of circular holes (31) are correspondingly arranged on the adjusting disk (30).

2. The pressure controller according to claim 1, characterized in that: The annular recess (13) is arranged outside the central hole (11) and the two are arranged coaxially, and the disk surfaces on both sides of the regulating disk (30) respectively abut against the bottom of the annular recess (13) and the steps arranged on the outer wall of the venturi tube (20) to form an axial limit fit.

3. The pressure controller according to claim 2, characterized in that: The hole cores of the through hole (12) and the circular hole (31) are arranged in parallel with the tube core of the venturi tube (20), and the diameter of the circular hole (31) is equal to the diameter of the through hole (12).

4. The pressure controller according to claim 3, characterized in that: A guide pin (32) is provided on the disk surface of the adjustment disk (30) and extends toward the bottom of the annular recess (13). The guide pin (32) is inserted into an arc-shaped guide groove (14) provided on the bottom of the annular recess (13) to form a guide sliding fit. The center of curvature of the arc-shaped guide groove (14) is colinear with the disk core of the adjustment disk (30).

5. The pressure controller according to claim 4, characterized in that: When the guide pin (32) is at the two end positions of the arc-shaped guide groove (14), the included angle between the center of the guide pin (32) and the connecting line of the core of the adjusting disk (30) is α, and the included angle between the tangent lines on both sides of the minimum aperture of the circular hole (31) of the core of the adjusting disk (30) is β, and α=β.

6. The pressure controller according to claim 4, characterized in that: An adjustment hole (15) is provided on the mounting plate (10). The bolt assembly (40) is inserted into the adjustment hole (15) from the outside of the mounting plate (10) and abuts against the adjustment plate (30). The length direction of the adjustment hole (15) and the abutment position are arranged at an angle to the connecting line of the core of the mounting plate (10). The bolt assembly (40) pushes the adjustment plate (30) to rotate into place and then locks it.

7. The pressure controller according to claim 6, characterized in that: The bolt assembly (40) comprises a guide bolt (41) fixedly arranged in the adjustment hole (15); the guide bolt (41) is a hollow structure and an adjustment screw (42) is threadedly connected in the hollow inner cavity; the inner end of the adjustment screw (42) abuts against the guide column (43); the guide pin (32) is clamped at a position between the two guide columns (43); the adjustment hole (15) comprises a threaded hole section corresponding to the guide bolt (41) and a light hole section corresponding to the guide column (43); the aperture of the threaded hole section matches the outer diameter of the guide bolt (41); the aperture of the light hole section matches the outer diameter of the guide column (43); a missing portion (16) for accommodating the bolt head of the guide bolt (41) is provided on the mounting plate (10); and a dust cover (44) is provided at the end of the hollow inner cavity of the guide bolt (41).

8. The pressure controller according to claim 1, characterized in that: The venturi tube (20) comprises a diffuser tube section (21) and a contraction tube section (22), the contraction tube section (22) being arranged adjacent to the oil inlet side, and the diffuser tube section (21) being arranged adjacent to the oil outlet side, the small diameter ends of the diffuser tube section (21) and the contraction tube section (22) being equal in diameter and adjacent to each other, a gap (23) being left between the two small diameter ends, and the two small diameter ends and the gap (23) together forming a negative zone of the venturi tube.

9. The pressure controller according to claim 8, characterized in that: The hole shape of the circular hole (31) of the regulating disk (30) is a variable diameter shape which is the same as the tube shape of the contraction tube section (22), and the hole shape of the through hole (12) of the mounting disk (10) is a variable diameter shape which is the same as the tube shape of the diffusion tube section (21).

10. The pressure controller according to claim 9, characterized in that: The inner diameter of the small diameter end of the circular hole (31) is equal to the inner diameter of the small diameter end of the through hole (12).

11. The pressure controller according to claim 1, characterized in that: An annular groove (111) is formed on the inner wall of the center hole (11) of the mounting plate (10); a diffuser tube section (21) and a contraction tube section (22) are inserted from both sides of the center hole (11); external threads on the outer walls of the diffuser tube section (21) and the contraction tube section (22) are threadedly connected with internal threads of the center hole (11); steps on the outer walls of the diffuser tube section (21) and the contraction tube section (22) abut against two ends of the center hole (11) to form an axial limit fit; a pressure collection area of ​​the negative zone of the venturi tube is located in the annular groove (111); a first channel (17) is radially formed on the outer wall of the mounting plate (10) and communicates with the annular groove (111); and a pipe joint connected to a pressure control valve is connected to the outer end of the first channel (17).

12. The pressure controller according to claim 2, characterized in that: A mounting hole (18) for connecting a pump oil pipe is provided on the surface of the mounting plate (10) in a circumferential direction, and an annular groove is also provided on the surface of the mounting plate (10) between the mounting hole (18) and the annular recess (13), wherein a sealing ring (50) is provided.

13. The pressure controller according to any one of claims 1 to 12, characterized in that: The mounting plate (10) is further provided with a second channel (19), the second channel (19) comprising a radial channel (191) radially opened from the outer wall of the mounting plate (10), an axial channel (192) extending from the inner end of the radial channel (191) by bending, an outlet (a) of the axial channel (192) being arranged at the bottom of the annular recess (13), a portion of the disc surface of the regulating plate (30) being cut away at a position corresponding to the outlet (a) of the axial channel (192) to form a relief portion (33), the outlet (a) being exposed outside the regulating plate (30), and a pipe joint connected to the pressure control valve being connected to the outer end of the radial channel (191).

14. The pressure controller according to claim 13, characterized in that: The avoidance portion (33) is arranged away from the guide pin (32).

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