Low cavitation gear pump

Abstract

The application provides a low-cavitation gear pump, which comprises a shell 1, a driving gear shaft 2, a driven gear shaft 3 and a pressure boosting valve assembly 4, the driving gear shaft 2 comprises a driving shaft 21 and a driving gear 22, the driving gear 22 comprises a pressure boosting valve seat mounting threaded hole 220, a one-way valve mounting hole 221, a reset spring cavity 222 and a medium outlet 223, the driven gear shaft 3 comprises a driven shaft 31 and a driven gear 32, the driven gear 32 comprises a pressure boosting valve seat mounting threaded hole 320, a one-way valve mounting hole 321, a reset spring cavity 322 and a medium outlet 323, the pressure boosting valve comprises a reset spring 41, a one-way valve 42 and a valve seat 43, and the valve seat 43 comprises a medium inlet 431, an external thread 432 and a hexagonal hole 433.

Description

Technical Field

[0001] This invention relates to the field of machinery, and more specifically to a low-cavitation gear pump. Background Technology

[0002] Gear pumps, as important power components, are widely used in the aerospace field due to their many advantages, such as simple structure, high power-to-weight ratio, good self-priming performance, strong anti-pollution ability, reliable operation, low cost and convenient maintenance.

[0003] Although gear pumps have a wide range of applications, they still have some prominent problems that need to be optimized due to their own structural characteristics. For example, severe cavitation damage, difficulty in completely eliminating oil trapped between gears, and large vibration and noise are all problems that restrict the further development of gear pumps.

[0004] Cavitation in gear pumps is a major design challenge. It manifests as follows: during fuel flow, as fuel pressure decreases, air separation and fuel vaporization produce bubbles. These bubbles burst under high pressure, typically generating impact forces up to 50 MPa, causing damage to components. Furthermore, the bursting bubbles contact the surfaces of components, triggering a series of physicochemical changes that further damage these surfaces. High-speed and high-power gear pumps experience even more severe cavitation damage.

[0005] With the development of aero engines towards higher thrust-to-weight ratios, higher maneuverability, and higher reliability, the requirements for fuel gear pump lifespan and vibration / noise reduction are increasing. However, cavitation during gear pump operation severely affects pump performance and reliability. Therefore, based on the conditions for cavitation occurrence, a low-cavitation gear pump is proposed. Summary of the Invention

[0006] The purpose of this invention is to solve the problem of cavitation caused by a low-pressure zone during the engagement and disengagement process of the driving and driven gears in existing gear pumps. Therefore, this invention provides a low-cavitation gear pump that can increase the pressure in the low-pressure zone during the disengagement process of the meshing gears, preventing cavitation and thus reducing the vibration and noise intensity caused by cavitation.

[0007] The technical solution of this invention is: a low-cavitation gear pump, comprising a housing 1, a drive gear shaft 2, a driven gear shaft 3, and a booster valve assembly 4. The drive gear shaft 2 includes a transmission shaft 21 and a drive gear 22. The drive gear 22 includes a booster valve seat mounting threaded hole 220, a check valve mounting hole 221, a return spring cavity 222, and a medium outlet 223. The driven gear shaft 3 includes a driven shaft 31 and a driven gear 32. The driven gear 32 includes a booster valve seat mounting threaded hole 320, a check valve mounting hole 321, a return spring cavity 322, and a medium outlet 323. The booster valve includes a return spring 41, a check valve 42, and a valve seat 43. The valve seat 43 includes a medium inlet 431, an external thread 432, and a hexagonal hole 433.

[0008] Both the driving gear shaft 2 and the driven gear shaft 3 are installed in the housing 1. The housing 1 is provided with an oil inlet 11 and an oil outlet 12. The teeth of the driving gear 22 and the driven gear 32 are provided with pressure boosting valve holes. A pressure boosting valve assembly 4 is installed in the pressure boosting valve holes on the teeth of the driving gear 22 and the driven gear 32. The assembly includes a return spring 41, a one-way valve 42 and a valve seat 43. The return spring 41 is installed on the one-way valve 42 and is coaxial with the one-way valve 42. One end of the spring is tightly attached to the end face of the return spring cavity on the gear teeth, and the other end is tightly attached to the end face of the one-way valve 42. The valve seat 43 is fastened to the teeth of the driving gear shaft 2 and the driven gear shaft 3 by threaded engagement with the valve seat mounting thread hole. The inclined surface 434 of the valve seat 43 is tightly attached to the sealing end face 421 of the one-way valve 42.

[0009] Furthermore, the valve orifice is divided into a booster valve seat mounting threaded hole 220, a one-way valve mounting hole 221, a return spring cavity 222, and a medium outlet 223; the center line of the valve orifice is located on the middle plane in the tooth thickness direction; the number of valve orifices is the same as the number of gear teeth, and each valve orifice is symmetrically distributed about the center line of the gear shaft; the valve orifice extends obliquely from near the tooth tip to the tooth root, connecting two adjacent tooth grooves, and the center lines of the booster valve seat mounting threaded hole 220, the one-way valve mounting hole 221, and the return spring cavity 222 should be coaxial.

[0010] Furthermore, the pressure on the medium inlet 431 side of the booster valve seat 43 is not greater than the sum of the pressure on the medium outlet 223 side and the preload force of the return spring 41, and the booster valve is in the closed state;

[0011] Conversely, when the pressure boosting valve opens, the medium flows through the valve seat 43, the compression return spring 41, and the opening check valve 42 into the suction zone 13, increasing the pressure in this suction zone, suppressing cavitation, and thus suppressing noise and vibration.

[0012] Furthermore, looking at the meshing point of the driving gear 21 and the driven gear 31, the medium inlet of the booster valve assembly is close to the gear pump inlet 11, and the medium outlet is close to the suction area 13 at the meshing point.

[0013] Furthermore, the diameter Ф1 of the medium inlet 431 on the valve seat 43 is equal to the diameter Ф2 of the medium outlet 223 on the gear valve hole.

[0014] Furthermore, the diameter of the inscribed circle of the hexagonal hole 433 on the valve seat 43 is smaller than the diameter Ф1 of the medium inlet 431.

[0015] Furthermore, the distance H = d between the center of one side of the threaded hole 220 of the booster valve seat and the tip of the gear tooth, where d is the outer diameter of the threaded section of the valve seat.

[0016] Furthermore, the range of the angle α between the center line of the booster valve orifice and the axis of the gear shaft is: 45°≤α≤65°, where the larger value is taken for the gear pitch circle diameter and the smaller value is taken for the gear pitch circle diameter.

[0017] In summary, this invention provides a low-cavitation gear pump. Based on the characteristics of a one-way valve structure, a one-way valve structure is introduced into the gear pump. Pressure boosting valves are installed on both the driving and driven gear teeth. When the pressure in the groove of the boosting valve on the medium inlet side is not greater than the sum of the medium outlet side pressure and the preload of the return spring, the boosting valve closes. If it is greater than the sum of the medium outlet side pressure and the preload of the return spring, the boosting valve opens, supplying medium from the higher pressure side to the lower pressure side, increasing the pressure on the lower pressure side, preventing cavitation, reducing noise and vibration, extending the service life of the gear pump, and improving its reliability. Attached Figure Description

[0018] Figure 1 This is a structural diagram of a low-cavitation gear pump according to the present invention;

[0019] Figure 2 This is a front view of the drive gear shaft in an embodiment of the present invention;

[0020] Figure 3 For along Figure 2 Sectional view along line A-A;

[0021] Figure 4 This is a triaxial side view of the booster valve assembly 4;

[0022] Figure 5 This is a cross-sectional view of the pressure booster valve assembly 4.

[0023] The attached figures are labeled as follows:

[0024] 1 – Housing; 2 – Driven gear shaft; 3 – Driven gear shaft; 4 – Pressure booster valve assembly; Housing inlet 11; Housing outlet 12; Suction area 13; 21 – Drive shaft; 22 – Driven gear; 220 – Pressure booster valve seat mounting threaded hole; 221 – Check valve mounting hole; 222 – Return spring cavity; 223 – Medium outlet; 31 – Driven shaft; 32 – Driven gear; 320 – Pressure booster valve seat mounting threaded hole; 321 – Check valve mounting hole; 322 – Return spring cavity; 323 – Medium outlet; 41 – Return spring; 42 – Check valve; 43 – Valve seat; 431 – Valve seat medium inlet; 432 – Valve seat external thread; 433 – Valve seat hexagonal hole; 434 Valve seat bevel; 421 – Check valve sealing end face. Detailed Implementation

[0025] Example 1

[0026] like Figure 1 , 2 As shown in Figures 4 and 5, this application provides a low-cavitation gear pump, including a housing 1, a drive gear shaft 2, a driven gear shaft 3, and a booster valve assembly 4. The drive gear shaft 2 includes a transmission shaft 21 and a drive gear 22. The drive gear 22 includes a booster valve seat mounting threaded hole 220, a check valve mounting hole 221, a return spring cavity 222, and a medium outlet 223. The driven gear shaft 3 includes a driven shaft 31 and a driven gear 32. The driven gear 32 includes a booster valve seat mounting threaded hole 320, a check valve mounting hole 321, a return spring cavity 322, and a medium outlet 323. The booster valve includes a return spring 41, a check valve 42, and a valve seat 43. The valve seat 43 includes a medium inlet 431, an external thread 432, and a hexagonal hole 433, wherein:

[0027] Both the driving gear shaft 2 and the driven gear shaft 3 are installed in the housing 1. The housing 1 is provided with an oil inlet 11 and an oil outlet 12. The teeth of the driving gear 22 and the driven gear 32 are provided with pressure boosting valve holes. A pressure boosting valve assembly 4 is installed in the pressure boosting valve holes on the teeth of the driving gear 22 and the driven gear 32. The assembly includes a return spring 41, a one-way valve 42 and a valve seat 43. The return spring 41 is installed on the one-way valve 42 and is coaxial with the one-way valve 42. One end of the spring is tightly attached to the end face of the return spring cavity on the gear teeth, and the other end is tightly attached to the end face of the one-way valve 42. The valve seat 43 is fastened to the teeth of the driving gear shaft 2 and the driven gear shaft 3 by threaded engagement with the valve seat mounting thread hole. The inclined surface 434 of the valve seat 43 is tightly attached to the sealing end face 421 of the one-way valve 42.

[0028] It should be noted that the driving gear 21 of the driving gear shaft 2 is integrated with the transmission shaft 22, and the driven gear 31 of the driven gear shaft 3 is integrated with the rotating shaft 32.

[0029] It should be noted that the pressure boosting valve assembly 4 consists of the return spring 41, the one-way valve 42, and the valve seat 43.

[0030] Specifically, the valve orifice is divided into a booster valve seat mounting threaded hole 220, a one-way valve mounting hole 221, a return spring cavity 222, and a medium outlet 223; the center line of the valve orifice is located on the middle plane in the tooth thickness direction; the number of valve orifices is the same as the number of gear teeth, and each valve orifice is symmetrically distributed about the center line of the gear shaft; the valve orifice extends obliquely from near the tooth tip to the tooth root, connecting two adjacent tooth grooves, and the center lines of the booster valve seat mounting threaded hole 220, the one-way valve mounting hole 221, and the return spring cavity 222 should be coaxial.

[0031] It can be seen that the geometric parameters of the valve holes on the teeth of the driving gear and the driven gear are consistent, and the valve holes should not weaken the strength of the gears.

[0032] Specifically, the pressure on the medium inlet 431 side of the booster valve seat 43 is not greater than the sum of the pressure on the medium outlet 223 side and the preload force of the return spring 41, and the booster valve is in the closed state; conversely, the pressure booster valve is opened, the medium flows through the valve seat 43, compresses the return spring 41, opens the one-way valve 42 and flows into the suction area 13, increasing the pressure in this suction area, suppressing cavitation, and thus suppressing the generation of noise and vibration.

[0033] Furthermore, looking at the meshing point of the driving gear 21 and the driven gear 31, the medium inlet of the booster valve assembly is close to the gear pump inlet 11, and the medium outlet is close to the suction area 13 at the meshing point.

[0034] Furthermore, the diameter Ф1 of the medium inlet 431 on the valve seat 43 is equal to the diameter Ф2 of the medium outlet 223 on the gear valve hole.

[0035] Furthermore, the diameter of the inscribed circle of the hexagonal hole 433 on the valve seat 43 is smaller than the diameter Ф1 of the medium inlet 431.

[0036] Furthermore, the centerline of the flow channel of the medium outlet 223 can be either a straight line or a curve.

[0037] Furthermore, the center lines of the booster valve seat mounting threaded hole 220 and the check valve mounting hole 221 should be coaxial with a diameter of φ0.05.

[0038] Furthermore, the distance H = d between the center of one side of the threaded hole 220 of the booster valve seat and the tip of the gear tooth, where d is the outer diameter of the threaded section of the valve seat.

[0039] Furthermore, the range of the angle α between the center line of the booster valve orifice and the axis of the gear shaft is: 45°≤α≤65°, where the larger value is taken for the gear pitch circle diameter and the smaller value is taken for the gear pitch circle diameter.

[0040] Example 2

[0041] like Figure 1 As shown, a low-cavitation gear pump includes a distribution plate housing 1, a driving gear shaft 2, and a driven gear shaft 3. Based on the characteristics of a check valve structure, a check valve structure is introduced into the gear pump. Pressure boosting valves are installed on both the driving and driven gear teeth to reduce noise, vibration levels, and cavitation.

[0042] In the gear pump, the teeth and grooves of the driving gear shaft 2 and the driven gear shaft 3 mesh with each other and rotate periodically within the housing 1. This causes the oil suction chamber volume to increase and the pressure to decrease, while the oil discharge chamber volume to decrease and the pressure to increase, thus achieving continuous oil intake and discharge. During operation, a closed space is formed between the meshing gears during disengagement. As the gears rotate, the oil in this closed space expands, and the pressure decreases. Figure 1 When the pressure drops to a certain level, the pressure boosting valves on the teeth of the drive gear shaft 2 and the driven gear shaft 3 open, replenishing oil to the enclosed space 13 and increasing the pressure there, thus preventing cavitation caused by the vaporization of fuel due to the reduced fuel pressure in the enclosed space.

[0043] like Figure 2 As shown, when the gear pump is working: the drive shaft 21 drives the driving gear 22 to rotate, which in turn drives the driven gear shaft 3 to rotate. The rotation of the meshing gears within the housing 1 causes the volume of the working chamber to repeatedly increase and decrease, thereby achieving the purpose of suction and discharge of oil. During the transition from oil discharge to oil suction, a closed space is formed between the meshing gear teeth. As the volume of this space increases, the pressure difference between the two sides of the gear teeth increases, exceeding the preload of the return spring 41. The medium enters through the medium inlet 431, compressing the return spring 41 and causing the one-way valve 42 to move towards the closed space 13. At this time, the pressure boosting valve opens, and the medium enters the closed space 13 through the medium outlet 223, increasing the pressure at that location.

[0044] like Figure 4 As shown in Figure 5, the present invention introduces a one-way valve structure into a gear pump. Pressure boosting valves are provided on both the driving gear and the driven gear teeth. The return spring 41, the one-way valve 42, and the valve seat 43 are sequentially installed into the return spring cavity 222, the one-way valve mounting hole 223, and the valve seat mounting threaded hole 220 on the gear teeth to form a pressure boosting valve, thereby reducing cavitation.

[0045] like Figure 3As shown, to ensure the function of the booster valve, viewed from the meshing point of the driving and driven gears, the medium inlet of the booster valve is close to the oil inlet of the gear pump, and the medium outlet is close to the meshing point. To reduce throttling losses, the diameter Ф1 of the medium inlet 431 and the diameter Ф2 of the medium outlet 221 on the gear valve hole are both 1.5mm. To ensure the installation of the valve seat 43, the inscribed circle diameter of the hexagonal hole 433 on the valve seat 43 is 2mm, which is larger than the diameter of the medium inlet 431. The valve seat 43 is installed using a special tooling. To avoid the valve hole being too close to the tooth tip, which would increase gear pump leakage, the distance H between the center of the valve hole on the side where the valve seat is installed and the tooth tip is 3mm (outer diameter of the threaded section of the valve seat installation), and the angle α between the center line of the valve hole and the gear shaft axis is 55°.

[0046] To fundamentally reduce the degree of cavitation, a one-way valve structure is introduced into the gear pump based on its structural characteristics. Pressure boosting valves are installed on both the driving and driven gear teeth. During gear pump operation, a closed space is formed between the meshing gears during disengagement. As the gears rotate, the oil pressure in this closed space decreases, and the pressure difference increases. When the pressure difference exceeds the preload of the return spring, the pressure boosting valve opens, replenishing oil to the closed space, increasing the pressure there, reducing gear pump cavitation, suppressing vibration and noise, and effectively improving the overall performance and reliability of the gear pump.

[0047] In summary, this implementation example sufficiently demonstrates that by introducing a one-way valve structure into a gear pump, it is possible to reduce noise and vibration levels and prevent cavitation, thereby improving the overall performance of the gear pump and extending its service life, meeting practical application needs, and demonstrating strong operability and high practical value.

Claims

1. A low- cavitation gear pump characterized by, The low-cavitation gear pump includes a housing, a drive gear shaft, a driven gear shaft, and a booster valve assembly. The drive gear shaft includes a transmission shaft and a drive gear. The drive gear includes a booster valve seat mounting threaded hole, a check valve mounting hole, a return spring cavity, and a media outlet. The driven gear shaft includes a driven shaft and a driven gear. The driven gear includes a booster valve seat mounting threaded hole, a check valve mounting hole, a return spring cavity, and a media outlet. The booster valve includes a return spring, a check valve, and a valve seat. The valve seat includes a media inlet, external threads, and a hexagonal hole, wherein: Both the drive gear shaft and the driven gear shaft are installed in the housing. The housing is provided with a housing oil inlet and a housing oil outlet. Both the drive gear and the driven gear have pressure boosting valve holes. A pressure boosting valve assembly is installed in the pressure boosting valve holes on the drive gear and the driven gear teeth. The assembly includes a return spring, a check valve, and a valve seat. The return spring is installed on the check valve and is coaxial with the check valve. One end of the spring is tightly attached to the end face of the return spring cavity on the gear teeth, and the other end is tightly attached to the end face of the check valve. The valve seat is fastened to the gear teeth of the drive gear shaft and the driven gear shaft by threaded engagement with the valve seat mounting thread hole. The inclined surface of the valve seat is tightly attached to the sealing end face of the check valve. The valve orifice is divided into a booster valve seat mounting threaded hole, a check valve mounting hole, a return spring cavity, and a medium outlet; the centerline of the valve orifice is located on the middle plane in the tooth thickness direction; the number of valve orifices is the same as the number of gear teeth, and each valve orifice is symmetrically distributed about the centerline of the gear shaft; the valve orifice extends obliquely from near the tooth tip to the tooth root, connecting two adjacent tooth grooves, and the centerlines of the booster valve seat mounting threaded hole, the check valve mounting hole, and the return spring cavity should be coaxial; The pressure at the medium inlet side of the booster valve seat is not greater than the sum of the pressure at the medium outlet side and the preload force of the reset spring, and the booster valve is in the closed state. Conversely, when the compression booster valve opens, the medium flows through the valve seat, compresses the return spring, opens the check valve, and flows into the suction area, increasing the pressure in this suction area, suppressing cavitation, and thus suppressing the generation of noise and vibration. Looking at the meshing point of the driving gear and the driven gear, the medium inlet of the booster valve assembly is close to the oil inlet of the housing, and the medium outlet is close to the suction area at the meshing point. The range of the angle α between the center line of the booster valve hole and the axis of the gear shaft is: 45°≤α≤65°, where the larger value is taken for the gear pitch circle diameter and the smaller value is taken for the gear pitch circle diameter.

2. The low cavitation gear pump according to claim 1, characterized in that, The diameter of the medium inlet on the valve seat, Ф1, is equal to the diameter of the medium outlet on the gear valve hole, Ф2.

3. The low cavitation gear pump according to claim 1, characterized in that, The diameter of the inscribed circle of the hexagonal hole on the valve seat is smaller than the diameter of the medium inlet, Ф1.

4. The low cavitation gear pump according to claim 1, characterized in that, The distance H = d between the center of one side of the mounting threaded hole of the pressure booster valve seat and the tip of the gear tooth, where d is the outer diameter of the mounting threaded section of the valve seat.

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