What are the requirements for the main oil pressure of automobiles?

1- valve core 2- valve body 3- spring a- pressure oil inlet of oil pump b- oil outlet c to gear selector valvE- oil inlet d connected with a to oil outlet of torque converter e-oil discharge passage f- throttle pressure adjustment inlet-pressure oil from oil pump enters from oil inlet a and acts on the right end of valve core, and two feedback oil pressures from throttle control valve and reverse oil circuit of manual valve act on the left end of valve core through oil inlet f.

When the engine load is small and the output power is small, the throttle adjustment pressure is also low, and the oil pressure acting on the right end of the valve core is high. When the force generated by the oil pressure is greater than the pre-tightening force of the spring at the left end of the spool and the force exerted on the spool by the throttle adjustment pressure, the spring will be compressed, the spool will move to the left, and the sealing shoulder in the middle of the spool will expose a part of the oil drain (the higher the oil pressure of the oil pump, the more oil drain will be exposed). Part of the oil from the oil pump is delivered to the gear selector valve through the oil outlet B, part of it is output to the torque converter through the oil outlet D, and part of it flows to the oil return disc through the oil outlet. So that the oil pressure drops until the thrust generated by the oil pressure is balanced with the resultant force of the pre-tightening force of the pressure regulating spring and the throttle regulating pressure, at which time the oil pressure output by the pressure regulating valve is lower than the input pressure of the oil pump; When the throttle opening increases and the output power increases, the increased throttle adjusting oil pressure will make the spool move to the right, and the sealing shoulder in the middle of the spool will block the oil drain, and the opening of the oil drain will decrease, and the oil drain will decrease or be in a closed state, so that the oil pressure will increase, and the oil pressure output by the regulating valve is higher than the input pressure of the oil pump. The greater the throttle opening, the higher the pressure output by the pressure regulating valve, and the oil pressure delivered to the gear selector valve and the torque converter will increase with the increase of power to be transmitted, thus keeping the oil pressure in a relatively stable range (usually 0.5MPa~ 1MPa).

At the right end of the slide valve, there is another feedback oil pressure from the pressure correction valve. The feedback oil pressure generates a left thrust on the slide valve, thereby reducing the oil pressure of the main oil passage regulated by the main oil passage pressure regulating valve.

When the automatic transmission is in the 1 gear or the second gear of the forward gear, the oil pressure in the reverse oil circuit is 0, the pressure regulating valve is closed, and the feedback oil pressure at the right end of the pressure regulating valve is also 0. When the transmission is in 3rd gear or overspeed gear, if the vehicle speed increases to a certain value, the pressure correction valve opens, and the pressure oil from the throttle valve enters the right end of the pressure regulating valve through the pressure correction valve. The thrust of the spool to the left increases, which reduces the oil pressure in the main oil circuit and the running resistance of the oil pump. When the automatic transmission is in reverse gear, the reverse oil pressure from the manual valve enters the left end of the spool, and the oil pressure at the left end of the spool increases, so the main oil pressure adjusted by the main oil pressure regulating valve also increases, which meets the needs of the main oil pressure in reverse gear. At this time, the oil pressure in the main oil circuit is called reverse oil pressure.