The hydraulic steering gear is used to control the action of the steering hydraulic cylinder to realize the hydraulic steering; when the steering hydraulic pump stops supplying oil, the manual steering is realized. The hydraulic steering gear is fixed on the steering bracket by screws and consists of a steering valve and a cycloid gear motor. Its structure is shown in the figure below.
1. Steering valve
The steering valve is composed of a valve body, a valve sleeve, a valve core, and a steel sheet return spring. There are 4 oil ports on the valve body, P port communicates with the hydraulic pump, O port communicates with the oil tank, A port and B port communicate with the left and right chambers of the steering hydraulic cylinder respectively. A check valve is installed between the oil inlet P and the oil return port 0. Seven oil holes are evenly distributed along the circumference of the valve body and they respectively lead to the seven working chambers of the cycloid motor.
There are 4 shoulders and 4 ring grooves on the outer surface of the valve sleeve. The 6 holes on the ring groove communicate with the oil return port on the valve body. There are two rows (6 in each row) of 12 e holes on the ring groove, which are always in communication with hole B on the valve body. There are two rows (6 in each row) of 12 d holes on the ring groove, which are always in communication with hole A on the valve body. There are 6 holes b and two rows of dense small holes a on the bottom ring groove, which are always in communication with the oil inlet P on the valve body. The 12 C holes on the shoulder can be divided into odd number and even number according to the order of arrangement. If there are several holes in the odd number hole that communicate with the oil inlet cavity of the cycloid motor, there are several holes in the even number hole that are connected to the cycloid. The oil drain cavity of the motor is connected.
There are three axial grooves of P, m, and n on the valve core, and there are 6 grooves for each groove. There are two rows of dense small holes a'on the circumference of the end that communicate with the inner cavity of the valve core.
When the valve core is in the neutral position, the three slots on it are closed by the valve sleeve, and the two rows of small holes a'at the end coincide with the two rows of small holes a on the valve sleeve correspondingly. When the spool is in the left or right turning operation, P slot connects the odd or even number of holes b and c of the valve sleeve; m slot connects the double or even number of holes d or e and c of the valve sleeve A singular number of holes are connected; the n-slot connects the double-row e-hole or d-hole of the valve sleeve with the f-hole. The t hole connects its center hole with the circuit oil port.
The valve sleeve and the valve core are matched and installed in the valve body, the two are connected by a shaft pin, and the steel sheet return spring is used to penetrate the long hole L of the valve core and the transverse groove of the valve sleeve to ensure the middle position.
2. Cycloidal motor
Cycloidal gear motors include stator, rotor, oil distribution plate, end cover, transmission shaft and so on. The stator, the oil distribution plate and the end cover are fixed on the steering valve body with screws, and the rotor is installed in the stator. One end of the drive shaft is connected with the rotor, and the other end is connected with the valve sleeve through a shaft pin.
The inner circle of the stator has 7 internal teeth, and the outer circle of the rotor has 6 external teeth. The rotor rotates around the center of the stator with the eccentricity as the radius. Due to the difference of 1 tooth between the two, when the position shown in the figure below is the starting point, the rotor rotates clockwise around the axis of the stator along each tooth of the stator. If the rotor rotates 6 times around the stator axis, the rotor rotates 6 teeth around its own axis in the opposite direction, that is, the rotor rotates 1 round around its own axis. The rotation of the rotor around the axis of the stator is called revolution, and the rotation around its own axis is called autorotation. The law of motion is: the rotor revolves around the stator 6 times at the same time, that is, the revolution speed of the rotor is 6 times its rotation speed, and two The direction of rotation is opposite