Shaft sleeve and gear pump

Abstract

The shaft sleeve comprises a shaft sleeve body, a high-pressure groove and an oil drainage and return groove are formed in the end face of the shaft sleeve body, a pressure equalizing groove is formed in the contact face of the shaft sleeve body and the end face 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 the floatability of the shaft sleeve is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic components, and in particular to a shaft sleeve and a gear pump. Background Art

[0002] In modern hydraulic technology, gear pump is a common mechanical equipment, and its working principle is to transport liquid through the rotation of gears. Because of its small size, simple structure and low requirements for oil cleanliness, the gear teeth of traditional spur gear pumps are engaged and disengaged at the same time during operation, which causes problems such as large flow pulsation, large vibration shock and high noise of gear pumps.

[0003] The structure of the helical gear pump is basically the same as that of the traditional spur gear pump. The difference is that the tooth profile is changed on the basis of the spur gear and the helix angle is increased, so that the meshing process of the helical gear is longer than that of the spur gear, and the transmission is smooth. Compared with the spur gear pump, its flow pulsation, vibration, noise and power loss are relatively low. However, due to the existence of the helix angle, the uneven force on both sides of the gear shaft during the meshing transmission will be affected by the axial force, which accelerates the wear between the gear end face and the shaft sleeve (or side plate), and increases the leakage of hydraulic oil caused by the end face clearance, resulting in a significant reduction in the volumetric efficiency of the pump.

[0004] In the prior art, a common method to eliminate axial force is to drill a hole at the position corresponding to the rear end cover and the axis of the gear shaft, and lead the high-pressure oil from the high-pressure area through the cavity to the lower end face of the plunger to offset part of the axial force. Chinese patent publication number CN114320888, a helical gear pump and a method for eliminating axial force thereof, provides a solution by adding components and improving adaptability, but it is too complicated and the increase in components will also bring hidden problems. Summary of the invention

[0005] The invention provides a shaft sleeve and a gear pump, which can reduce the axial force of the helical gear pump only by modifying the shaft sleeve and using a suitable installation method.

[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 with the high-pressure groove.

[0007] Furthermore, the pressure equalizing groove includes an arc groove and a diverter groove, and the arc groove has the same curvature as the shaft hole of the sleeve body;

[0008] The diverter 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 on the arc groove from the inside to the outside.

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

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

[0012] A helical gear pump uses the above-mentioned shaft sleeve.

[0013] A method for installing a helical gear pump shaft sleeve comprises installing a first shaft sleeve in the opposite direction according to the axial force direction of the active helical gear, wherein the first shaft sleeve is a pressure equalizing groove arranged on the contact surface with the end surface of the active gear of the helical gear pump.

[0014] Furthermore, a second sleeve is installed at one end of the helical gear in the axial force direction, and the second sleeve is a pressure equalizing groove arranged on the contact surface with the end surface of the passive gear of the helical gear pump.

[0015] The present invention forms a reaction force by arranging a pressure equalizing groove on the shaft sleeve, which is relatively balanced with the axial force in the helical gear pump, thereby effectively eliminating the axial force generated by the helical gear pump. Through a reasonable layout of the pressure equalizing groove, the driving gear and the driven gear can maintain a relative balance of axial force during the operation of the gear pump, so as to improve the working efficiency and service life of the gear pump. At the same time, it can also achieve the effects of low wear, light sweeping of the bore, and reduction of oil entrapment, and reduce the wear of the shaft sleeve end face. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the shaft sleeve structure of the present invention Figure 1 .

[0017] Figure 2 Schematic diagram of the shaft sleeve structure of the present invention Figure 2 . DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of 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.

[0019] The axial force generated by the helical gear pump during operation mainly comes from two parts. One is the axial force generated by the pressure difference between the tooth surfaces on both sides of the gear teeth, which is usually called the axial hydraulic pressure. The other is the force generated in the axial direction due to the meshing of the master and slave gears during operation, which is usually called the axial meshing force. Among them, for the driving gear, its axial meshing force is in the same direction as the axial hydraulic pressure, and for the driven gear, the two are in opposite directions, that is, the axial force on the driving gear shaft is much greater than that on the driven gear shaft. Therefore, the axial force of the balanced helical gear pump is mainly to balance the axial force on the driving gear shaft. Of course, due to some special helical gear pumps, due to their parameter settings, the axial force on the driven gear will also have a certain impact.

[0020] Example 1

[0021] A shaft sleeve comprises a shaft sleeve body 1, on which a high pressure groove 3 and an oil drain 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 a helical gear pump, and the pressure equalizing groove is connected with the high pressure groove.

[0022] The pressure equalizing groove includes an arc groove 2 and a diverter groove 6. The arc groove 2 has the same arc as the shaft hole 7 of the sleeve body. The diverter groove 6 is evenly distributed on the arc groove 2 and communicates with the arc groove 2. One end of the diverter groove 6 is communicated with the arc groove 2, and the other end extends from the shaft hole of the sleeve body from the inside to the outside on the arc groove 2.

[0023] The arc length 8 of the notch of the circular arc groove is greater than or equal to the corresponding thickness of a helical gear tooth. This design is to prevent the high-pressure area from communicating with the low-pressure area.

[0024] An oil return hole 5 is arranged on the oil leakage return groove 4. The oil leakage return groove 4 and the oil return hole 5 are used to collect the leaked oil, so that the sealing oil is connected with the low-pressure area to realize the recycling of the leaked oil.

[0025] The present invention makes the line of action of the sleeve clamping force coincide with the line of action of the reverse thrust, offsetting the axial force to a certain extent, effectively preventing the sleeve from wearing eccentrically, and enhancing the floatability of the sleeve. The number of pressure equalizing grooves is designed according to the magnitude of the axial force received and the demand for dispersion force, and the groove depth and groove width of the pressure equalizing groove are designed according to the working conditions and fluid characteristics of the helical gear oil pump. The relevant design on the sleeve of the present invention can also be applied to side plates with the same function but different structures.

[0026] Example 2

[0027] A helical gear pump uses the above-mentioned shaft sleeve.

[0028] Example 3

[0029] A method for installing a helical gear pump shaft sleeve comprises installing a first shaft sleeve in the opposite direction according to the axial force direction of the active helical gear, wherein the first shaft sleeve is a pressure equalizing groove provided on the contact surface with the end surface of the active gear of the helical gear pump. A second shaft sleeve is installed at one end in the axial force direction of the helical gear, wherein the second shaft sleeve is a pressure equalizing groove provided on the contact surface with the end surface of the passive gear of the helical gear pump.

[0030] The sleeves are installed on both sides of the gear shaft. A pressure equalizing groove is set on the sleeve installed on the lower side at 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 channel in the high-pressure groove and the pressure equalizing groove. The sleeve is close to the end face of the gear shaft, generating a force in the opposite direction to the axial force. Therefore, the axial force can be balanced. Since the driven gear shaft will also be affected by the axial force, the sleeve will be worn eccentrically, affecting the service life of the sleeve and the gear shaft. According to the relevant formula, the axial force direction of the driven gear shaft is opposite to that of the driving gear shaft. Therefore, a pressure equalizing groove will be set on the sleeve on the other side at one side of the driven gear shaft, and the corresponding groove shape will be designed according to the actual situation.

[0031] The present invention can arrange a pressure equalizing groove 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.

[0032] Analysis of force.

[0033] 1. Technical parameters

[0034] Number of teeth <![CDATA[Z0]]> Pressure Angle <![CDATA[α n ]]> Helix Angle β <![CDATA[Method Surface modulus > <![CDATA[m n ]]> Tooth width B Addendum circle <![CDATA[D a ]]> Tooth root circle <![CDATA[D f ]]>

[0035] 2. Calculation of gear axial force

[0036] 1. Axial force on the gear shaft

[0037] The oil outlet pressure p of the pump is 20Mpa. According to the reference (Wu Yifei. Design of double arc helical gear hydraulic pump and its axial force analysis [D]. Shandong University, 2020), the axial force generated by the hydraulic pressure acting on the gear shaft can be obtained:

[0038]

[0039] Where: Δp-gear pump inlet and outlet pressure difference, 20MPa;

[0040] Axial force component caused by meshing force:

[0041]

[0042] Where: R a - Tip circle radius;

[0043] R-pitch circle radius.

[0044] 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.

[0045] Therefore, the axial force on the main gear shaft is:

[0046]

[0047] 2. Axial balance force of the rear cover

[0048] 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:

[0049]

[0050] Where: F z1 -Axial balance force on the driving gear, N;

[0051] F z2 -Axial balance force on the driven gear, N;

[0052] D1-the aperture of the driving wheel of the rear cover;

[0053] D2- The hole diameter of the driven wheel of the rear cover.

[0054] 3. Axial balancing force of the pressure equalizing groove

[0055] Pressure equalizing tank area S 槽1 .but

[0056] F 槽1 = p·S 槽1

[0057] Axial balance F' 槽 =F 槽1 tanβ

[0058] Conclusion

[0059] The axial force balance on the driving gear needs to reach F' 槽 Infinitely close to F az1 +F z1 .

Claims

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

2. A bushing according to claim 1, characterized in that: The pressure equalizing groove includes an arc groove and a diverter groove, and the arc groove is consistent with the axial hole of the sleeve body; The diverter grooves are evenly distributed on the circular arc groove and communicated with the circular arc groove.

3. A bushing 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 bushing 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 corresponding tooth thickness of a helical gear.

5. A bushing according to claim 1, characterized in that: The oil drain and return groove is provided with an oil return hole.

6. A gear pump, characterized in that: A shaft sleeve according to any one of claims 1 to 6.

7. A method for installing a shaft sleeve according to claim 1, characterized in that: According to the axial force direction of the active helical gear, a first sleeve is installed in the opposite direction, wherein the first sleeve is a pressure equalizing groove arranged on the contact surface with the end surface of the active gear of the helical gear pump.

8. A method for installing a shaft sleeve according to claim 7, characterized in that: A second sleeve is installed at one end of the helical gear in the axial force direction, and the second sleeve is a pressure equalizing groove arranged on the contact surface with the end surface of the passive gear of the helical gear pump.

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