Two gear type involute external gear motor
(1) Two gear type involute external gear motor
① Fixed clearance involute external gear motor figure f shows the structure of fixed clearance involute external gear motor. The side plates on both sides of the gear are made of high-quality carbon steel 08F with 0.5-0.7mm thick phosphor bronze sintered on the surface. The side plate is only wear-resistant and has no end clearance compensation function. Fixed clearance can reduce the friction torque and improve the starting performance, but the volumetric efficiency is low. Cm-f gear motor made in China is of this structure. Its rated pressure is 14MPa, displacement is 11-40ml / R, torque is 20-70n · m, and speed is 1900-2400r / min.
② Involute external gear motor with automatic axial clearance compensation figure g shows the structure of involute external gear motor with automatic axial clearance compensation. Sealing rings 1-4 are arranged at the outer ends of shaft sleeves 9 and 10, and the central sealing ring 1 surrounds two bearing holes, forming an "8" shaped area A1 with contraction in the middle. Because area A1 is connected with oil drain hole 14 through two bearings, the pressure in area A1 is equal to that in oil leakage chamber. The side sealing rings 2 and 3 are symmetrically arranged on both sides of the sealing ring 1 (the sealing rings 2 and 3 each have a length that directly contacts with the sealing ring 1), forming diamond shaped areas A2 and A3 respectively. A2 is communicated with the oil inlet chamber 6 through channel 5, and A3 is communicated with the oil return chamber 7 through channel 8. The outer sealing ring 4 is also arranged in a diamond shape, surrounding the sealing rings 1, 2 and 3 (there are two lengths on the sealing ring 4, which are in direct contact with the sealing rings 2 and 3 respectively). Because both sides of the sealing rings 2 and 3 are in direct contact with the sealing rings 1 and 4 respectively, two areas A4 and A5 are formed in the surrounding ring of the sealing ring 4. Due to leakage and oil leakage, the pressure in A4 and A5 is very close to the pressure in the high pressure chamber power. The sealing ring 4 is clamped between the housing 12 and the front cover 11 (rear cover 13), the sealing ring 1 is clamped between the shaft sleeve and the front cover (rear cover), and the parts of the sealing rings 2 and 3 close to the sealing ring 4 are kept between the housing and the front cover (rear cover). All sealing rings are embedded in the grooves of the front cover (rear cover). The parts close to each other can be directly contacted to simplify the processing and assembly process and reduce the cost.
③ Figure h and figure I show the structure of the gear motor with automatic compensation of both axial and radial clearance and the force on the gear. The shell 9 of the motor is made of seamless steel tube. The tooth tips of gears 1 and 11 are not in contact with the shell, but are directly exposed to high-pressure oil. They only contact with the radial clearance sealing block in a small range (two teeth) near the low-pressure area. The radial clearance sealing block can automatically compensate the radial clearance. When the motor rotates in the opposite direction, the radial clearance sealing block plays the same role. The motor's floating sleeve 8 and 12 (also used as needle roller bearing seat) can be used for pressure compensation of axial clearance. The function of O-ring is to limit the low pressure area in a very small range from the axial direction, and also limit the pressure surface on the back of the shaft sleeve to achieve the pressure balance of the shaft sleeve. When the motor rotates in the opposite direction, the O-ring seal plays the same role.
When the motor has not been put into operation, the radial seal blocks 2 and 2 'are respectively close to the gear under the action of the spring plates 3 and 3' (Fig. h). When the high-pressure oil is fed into the gear motor from the right side (Fig. I), the sealing block 2 is out of contact with the gear under the action of the high-pressure oil inside. At this time, only the sealing block 2 'in the low-pressure chamber plays a sealing role. In addition to the low pressure cavity and the transition zone between the sealing block 2 'and the gear, the rest of the gear and the outside of the sealing blocks 2 and 2' are soon under the action of high pressure liquid. At this time, the inner and outer sides of the sealing block 2 are all under the action of high-pressure liquid (Fig. J), so the hydraulic pressure acting on the sealing block 2 is actually balanced. Although there is a spring plate acting on the outer side, because the spring force is very weak, the tight force on the gear is very small. On the contrary, due to the action of high pressure oil on the outside of the sealing block 2 ', the pressing force is greater than the reverse thrust (the reverse thrust is equal to the sum of the hydraulic pressure in the transition zone and the hydraulic pressure in the low pressure chamber). The sealing block 2' contacts the gear tightly and keeps the best radial clearance. The larger the pressure difference is, the more reliable the sealing function of the sealing block is. Under the action of the hydraulic torque formed by the pressure difference △ p between the inlet and outlet, the two gears drag the load to rotate in the direction shown in Fig. I. When the motor reverses, the left side of the motor is a high-pressure cavity, and the right side is a low-pressure cavity. The sealing block 2 'loses its sealing function. Under the action of hydraulic pressure, the sealing block 2 tightly contacts the gear teeth near the low-pressure cavity, seals the low-pressure area, and forms a transition area, so as to ensure that the performance of the motor in reverse rotation is exactly the same as that in forward rotation.
The motor has the following structural features.
a. Because of the large number of teeth in the motor, there are only two teeth contact between the radial clearance seal block and the gear, and the transition zone is very small (only one tooth to tooth), and the arc length of the transition zone is as close to the node as possible, so the corner mouth of the low pressure zone is limited to a very small range, and the O-ring is used to restrict and seal between the seal block, shaft sleeve and the front cover (back cover), while the rest of the ring is closed Therefore, the friction surface between the shaft sleeve and the gear can be designed to be very small (the shaft sleeve is cut out, see Fig. h). In this way, in the axial and radial direction, the friction surface is reduced, the mechanical efficiency and output torque are improved, and the starting performance is improved.
b. Because most of the circumference of the gear is under high pressure (Fig. I), the radial load of the gear bearing is greatly reduced, so the friction torque of the bearing is greatly reduced, the output torque is increased, and the starting pressure difference △ P is reduced. The starting characteristics are improved and the service life of bearing and motor is increased.
c. The seamless steel tube shell without holes can be used for the motor. Not only the inner part does not need to be processed, but also the circular steel pipe has good stress and is not easy to deform, which can improve the service pressure of the motor.
d. The bolt 6 (Fig. h) connecting the front cover, the back cover and the housing runs through the inside of the housing.
E. in addition to needle bearings on both sides of the gear, rolling bearings are also installed on the shaft end of the output shaft, so the output shaft end can bear certain radial force, which improves the adaptability of the gear motor.
f. The tip clearance of general gear motor is determined by many factors, such as the manufacturing accuracy of gear shaft, shaft sleeve, bearing clearance and shell hole, and the installation error of center distance, etc. The gear motor with radial clearance seal block overcomes the above shortcomings. Because the radial clearance seal block is floating in the shell and pressed on the floating shaft sleeve (Fig. I) and the gear outer circle by oil pressure, the clearance at the top of the gear is only determined by the clearance between the floating shaft sleeve at the top of the gear and the needle roller bearing, which is relatively easy to control. In this way, the best clearance value can be obtained. When the seal block is worn, it can be automatically compensated under the action of oil pressure, so as to achieve higher volumetric efficiency, and correspondingly improve the starting torque and low-speed performance.
g. The radial clearance seal block of the low pressure cavity of the motor is deformed after being forced. In this way, a better sealing effect is achieved under high pressure, and a small amount of radial compensation can be obtained, while the floating shaft sleeve can realize axial compensation, so it can be used for higher pressure.
h. The gear teeth of the motor are straight teeth and helical teeth. The helical teeth adopt a helix angle of 2 ° 39 ', which improves the running stability and reduces the noise.
The rated working pressure of the gear motor is 17Mpa, and the volumetric efficiency can reach 95%.