Shaft sleeve for improving axial balance of gear pump

Abstract

The utility model discloses a shaft sleeve for improving the axial balance of a gear pump, which comprises a shaft sleeve body, a high-pressure groove and an oil drainage and return groove are arranged on the end surface of the shaft sleeve body, a pressure equalizing groove is arranged on the contact surface of the shaft sleeve body and the end surface of a driving gear or a driven gear of a bevel gear pump, and the pressure equalizing groove is communicated with the high-pressure groove. The action line of pressing force of the shaft sleeve coincides with the action line of reverse thrust, axial force is counteracted to a certain degree, eccentric wear of the shaft sleeve is effectively prevented, and floatability of the shaft sleeve is enhanced.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic components, in particular to a shaft sleeve for improving the axial balance of a gear pump. Background Art

[0002] In modern hydraulic technology, gear pumps are a common mechanical device that transports fluids through the rotation of gears. Due to their small size and simple structure, they require less clean oil. However, traditional spur gear pumps experience simultaneous engagement and disengagement of their teeth during operation, resulting in significant flow pulsation, vibration, and noise.

[0003] Helical gear pumps share a similar structure to traditional spur gear pumps. The difference is that the tooth profile of spur gears is modified by increasing the helix angle, making the meshing process longer than that of spur gears, resulting in smoother transmission. Compared to spur gear pumps, helical gear pumps offer relatively low flow pulsation, vibration, noise, and power loss. However, due to the helix angle, the uneven force on both sides of the gear shaft during meshing transmission causes axial force, accelerating wear between the gear end faces and the shaft sleeve (or side plate). This can also increase hydraulic oil leakage due to end-face clearance, significantly reducing the pump's volumetric efficiency.

[0004] A common method for eliminating axial force in the prior art is to drill a hole in the rear end cap corresponding to the axis of the gear shaft. This allows high-pressure oil to be directed from the high-pressure area through a cavity to the lower end face of the plunger, thereby offsetting some of the axial force. Chinese Patent Publication No. CN114320888, a helical gear pump and method for eliminating axial force therewith, offers a solution by adding components and improving adaptability. However, this approach is complex, and the added components can also introduce hidden problems. Utility Model Content

[0005] The utility model provides a shaft sleeve for improving the axial balance of a gear pump. The axial force of the helical gear pump can be reduced only by modifying the shaft sleeve.

[0006] A shaft sleeve comprises a shaft sleeve body, on which a high-pressure groove and an oil drain and return groove are arranged. The invention is characterized in that a pressure equalizing groove is arranged on the contact surface between the shaft sleeve body and the end face of the driving gear or the driven gear of the helical gear pump, and the pressure equalizing groove is connected to the high-pressure groove.

[0007] Furthermore, the pressure equalizing groove includes an arc groove and a diverter groove, and the arc groove is consistent with the curvature of the shaft hole of the sleeve body;

[0008] The diversion grooves are evenly distributed on the circular arc groove and communicated with the circular arc groove.

[0009] Furthermore, one end of the diverter groove is connected to the arc groove, and the other end extends from the shaft sleeve body from the inside to the outside on the arc groove.

[0010] Furthermore, the arc length of the notch of the circular arc groove is greater than or equal to the thickness of a corresponding helical gear tooth.

[0011] Furthermore, an oil return hole is provided on the oil drain and return groove.

[0012] This utility model provides a pressure-equalizing groove on the shaft sleeve to create a reaction force that balances the axial force in the helical gear pump, effectively eliminating the axial force generated by the helical gear pump. This rational layout of the pressure-equalizing grooves ensures a relative balance of axial forces between the driving and driven gears during operation, improving the gear pump's operating efficiency and service life. Furthermore, it reduces wear, minimizes bore clearance, reduces oil entrapment, and reduces wear on the shaft sleeve end face. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the shaft sleeve structure of the utility model Figure 1 .

[0014] Figure 2 This is a schematic diagram of the shaft sleeve structure of the utility model Figure 2 . DETAILED DESCRIPTION

[0015] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0016] The axial force generated by a helical gear pump during operation primarily comes from two sources: the first is the axial force generated by the pressure difference between the tooth flanks on either side of the gear teeth, commonly referred to as the axial hydraulic pressure. The second is the force generated in the axial direction by the meshing action of the driving and driven gears during operation, commonly referred to as the axial meshing force. For the driving gear, the axial meshing force and the axial hydraulic pressure act in the same direction; for the driven gear, the two forces act in opposite directions. This means that the axial force acting on the driving gear shaft is much greater than that acting on the driven gear shaft. Therefore, the axial force of the balanced helical gear pump primarily balances the axial force acting on the driving gear shaft. Of course, for some specialized helical gear pumps, the axial force acting on the driven gear can also have a certain impact due to the parameter settings.

[0017] Example 1

[0018] A shaft sleeve comprises a shaft sleeve body 1, on which a high-pressure groove 3 and an oil drain and return groove 4 are arranged. A pressure equalizing groove is arranged on the contact surface between the shaft sleeve body 1 and the driving gear end face or the driven gear of the helical gear pump, and the pressure equalizing groove is connected to the high-pressure groove.

[0019] The pressure-equalizing groove includes a circular arc groove 2 and a diverter groove 6. The circular arc groove 2 has the same curvature as the shaft hole 7 of the sleeve body. The diverter grooves 6 are evenly distributed on the circular arc groove 2 and communicate with the circular arc groove 2. One end of the diverter groove 6 communicates with the circular arc groove 2, and the other end extends from the shaft hole of the sleeve body from the inside to the outside on the circular arc groove 2.

[0020] The arc length 8 of the notch of the arc groove is greater than or equal to the thickness of a corresponding helical gear tooth. This design is to prevent the high-pressure area from communicating with the low-pressure area.

[0021] An oil return hole 5 is provided on the oil drain return groove 4. The oil drain return groove 4 and the oil return hole 5 are used to collect leaked oil, connect the sealing oil with the low-pressure area, and realize the recycling of the leaked oil.

[0022] This new design allows the line of action of the sleeve's compression force to coincide with the line of action of the reverse thrust, offsetting the axial force to a certain extent, effectively preventing eccentric wear of the sleeve and enhancing its floatability. The number of pressure-equalizing grooves is designed based on the magnitude of the axial force and the required force dispersion, and the depth and width of the pressure-equalizing grooves are designed based on the operating conditions and fluid characteristics of the helical gear oil pump. The design of this new sleeve can also be applied to side panels with the same function but different structures.

[0023] Example 2

[0024] A helical gear pump uses the above-mentioned shaft sleeve.

[0025] Example 3

[0026] A method for installing a helical gear pump shaft sleeve comprises installing a first shaft sleeve in the opposite direction of the axial force of the driving helical gear. The first shaft sleeve comprises a pressure-equalizing groove provided on the surface contacting the end face of the driving gear of the helical gear pump. A second shaft sleeve is installed at one end of the helical gear in the axial force direction. The second shaft sleeve comprises a pressure-equalizing groove provided on the surface contacting the end face of the driven gear of the helical gear pump.

[0027] The sleeves are installed on both sides of the gear shaft. A pressure-equalizing groove is set on the lower sleeve on one side of the main gear shaft. The pressure oil in the high-pressure area can act on one end of the main gear shaft through the oil channels in the high-pressure groove and the pressure-equalizing groove. The sleeve is tightly attached to the end face of the gear shaft, generating a force in the opposite direction of the axial force, thereby balancing the axial force. Since the driven gear shaft is also affected by the axial force, the sleeve will cause uneven wear, affecting the service life of the sleeve and gear shaft. According to relevant formulas, the direction of the axial force on the driven gear shaft is opposite to that of the driving gear shaft. Therefore, a pressure-equalizing groove is set on the other side of the sleeve on one side of the driven gear shaft, and the corresponding groove shape is designed according to actual conditions.

[0028] The utility model can arrange pressure equalizing grooves at the driving gear end or both the driving and driven gear ends according to the displacement and pressure of the helical gear pump to form a reaction force.

[0029] Force analysis.

[0030] 1. Technical Parameters

[0031] Number of teeth <![CDATA[Z0]]> pressure angle <![CDATA[α n ]]> Helix angle β Normal modulus <![CDATA[m n ]]> Tooth width B Addendum circle <![CDATA[D a ]]> Root circle <![CDATA[D f ]]>

[0032] 2. Calculation of gear axial force

[0033] 1. Axial force on the gear shaft

[0034] The pump outlet pressure p is 20 MPa. According to the reference (Wu Yifei. Design and Axial Force Analysis of Double Arc Helical Gear Hydraulic Pump [D]. Shandong University, 2020), the axial force component generated by the hydraulic pressure acting on the gear shaft can be obtained as follows:

[0035]

[0036] Where: Δp-gear pump inlet and outlet pressure difference, 20MPa;

[0037] Axial force component caused by meshing force:

[0038]

[0039] Where: R a - tooth tip radius;

[0040] R-pitch circle radius.

[0041] The meshing force of the main gear shaft on the slave gear shaft is indirectly generated by the hydraulic pressure acting on the slave gear shaft. The axial force generated by the mutual meshing between the main gear and the slave gear is a pair of interactive forces. Therefore, the axial force of the main gear acting on the slave gear and the hydraulic pressure acting on the slave gear shaft are a pair of interactive forces of equal magnitude and opposite direction, that is, the axial force on the driven shaft is basically zero. Although the axial force generated by the meshing force on the driven shaft is balanced by the hydraulic pressure, the axial force on the driving shaft will be strengthened due to the axial force generated by the hydraulic pressure. Therefore, the axial force balance of the helical gear pump mainly refers to the balance of the axial force on the main gear shaft.

[0042] Therefore, the axial force on the main gear shaft is:

[0043] F az1 =F azp +F aNz (8)

[0044] 2. Axial balance force of the back cover

[0045] According to the reference (Research on Key Technologies of High-Performance Circular Arc Gear Pumps [D]. Harbin Institute of Technology, 2016), the axial balancing force of the rear cover acting on the gear shaft can be calculated as follows:

[0046]

[0047] Where: F z1 -Axial balance force on the driving gear, N;

[0048] F z2 -Axial balance force on the driven gear, N;

[0049] D1-the aperture of the driving wheel of the rear cover;

[0050] D2-Aperture of the driven wheel on the rear cover.

[0051] 3. Axial balance force of the pressure equalizing groove

[0052] Pressure equalizing tank area S 槽1 .but

[0053] F 槽1 =p·S 槽1

[0054] Axial balance F' 槽 =F 槽1 tanβ

[0055] 3. Conclusion

[0056] The axial force balance on the driving gear must reach F' 槽 Infinitely close to F az1 +F z1 .

Claims

1. A shaft sleeve for improving the axial balance of a gear pump, comprising a shaft sleeve body, a high-pressure groove and an oil drain and return groove being arranged on the end surface of the shaft sleeve body, characterized in that: A pressure equalizing groove is provided on the contact surface between the shaft sleeve body and the end surface of the driving gear or the driven gear of the helical gear pump, and the pressure equalizing groove is communicated with the high-pressure groove.

2. A shaft sleeve for improving the axial balance of a gear pump according to claim 1, characterized in that: The pressure equalizing groove includes a circular arc groove and a diverter groove, and the arc of the circular arc groove is consistent with the curvature of the shaft hole of the sleeve body; The diversion grooves are evenly distributed on the circular arc groove and communicated with the circular arc groove.

3. A shaft sleeve for improving the axial balance of a gear pump according to claim 2, characterized in that: One end of the diverter groove is communicated with the arc groove, and the other end extends from the shaft sleeve body on the arc groove from the inside to the outside.

4. A shaft sleeve for improving the axial balance of a gear pump according to claim 2, characterized in that: The arc length of the notch of the circular arc groove is greater than or equal to the thickness of a corresponding helical gear tooth.

5. The shaft sleeve for improving the axial balance of a gear pump according to claim 1, characterized in that: An oil return hole is provided on the oil drain and return groove.

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