Clamping force control and speed ratio control coupled continuously variable transmission sliding control device

Abstract

The invention discloses a clamping force control and speed ratio control coupled continuously variable transmission sliding control device. The clamping force control and speed ratio control coupled continuously variable transmission sliding control device comprises a continuously variable transmission, a hydraulic device and an electronic control unit, wherein the continuously variable transmission comprises a driving wheel, a driven wheel and a metal belt E; the driving wheel comprises a movable bevel wheel and a fixed bevel wheel; the driven wheel comprises a movable bevel wheel and a fixedbevel wheel; the movable bevel wheel of the driving wheel and the movable bevel wheel of the driven wheel are each provided with a speed sensor; and the hydraulic device comprises a speed ratio control hydraulic loop and a clamping force control hydraulic loop. The clamping force control and speed ratio control coupled continuously variable transmission sliding control device is simple in structure and low in manufacturing cost. The coupling effect between clamping force control and speed ratio control is actively utilized, on the basis of guaranteeing the safety of clamping force, speed ratio control is intervened by adjusting the pressure of oil cylinders of the driving wheel and the driven wheel in a combined manner, the controllable range of the speed ratio change rate is enlarged, the continuously variable transmission can be kept in the optimal sliding interval all the time, the clamping force of a belt wheel is reduced, and therefore hydraulic losses are reduced, the transmission efficiency is improved, and the fatigue life of the metal belt is prolonged.

Description

technical field [0001] The invention relates to a slip control device of a continuously variable transmission coupled with clamping force control and speed ratio control. Background technique [0002] Metal belt CVT is a friction transmission device, through the clamping force provided by the driven pulley, friction is generated between the metal sheet and the pulley, and the metal sheet generates friction between adjacent friction sheets under the action of friction. Squeeze the thrust, and then realize the transmission of torque from the driving wheel to the driven wheel. However, during the torque transmission process of the continuously variable transmission, the redundant clamping force will cause a large friction loss between the metal plate and the pulley. By controlling the clamping force to maintain a certain relative slip between the metal sheet and the pulley, the clamping force of the pulley can be reduced, thereby reducing the hydraulic loss, and at the same ti...

AI Technical Summary

Problems solved by technology

However, if the clamping force is too small, it means that the slip rate between the metal belt and the pulley will be large, which can reduce the friction and wear between the metal sheet and the pulley to a certain extent, and protect the metal sheet. However, the output torque of the engine cannot be transmitted reliably and efficiently. At the same time, because the transmission is extremely sensitive to fluctuations in external loads, the clamping force will not be sufficient to meet the torque transmission requirements, resulting in macroscopic slippage and variable speed. The mechanism is very easy to damage

And if the clamping force is too large, it means that the slip rate between the metal belt and the pulley will be very small. Although this can improve the transmission efficiency of the continuously variable transmission, it will increase the friction loss between the metal belt and the pulley. , reduce the life of the metal belt and pulley, and at the same time, the hydraulic system must output greater flow to provide greater hydraulic clamping force, thus increasing the hydraulic loss of the transmission mechanism

[0003] There are some examples of related inventions, but they are all essentially different from the present invention. Among the existing technical solutions for controlling CVT speed ratio devices, such as "pump-controlled CVT electro-hydraulic control system" (CN102494128A), "a hydraulic mechanical Continuously variable transmission speed ratio adjustment automatic control system" (CN108506482A), "A hydraulic-mechanical continuously variable transmission speed ratio adjustment automatic control device (CN108506482A)" and "An electro-hydraulic control system for a continuously variable transmission with high-speed on-off valve pilot control ( CN110425276A)", the technology proposed by the first device: the CVT hydraulic system only realizes the change of the speed ratio through the positive and negative rotation of an oil pump, and then realizes the control of the clamping force through an oil charge pump, without using other valve control Although this reduces the overflow loss, the speed ratio control accuracy of this device is very low, and the clamping force control is very unstable; the technology proposed by the second and third devices: CVT hydraulic system adopts double pump adjustment, And use the high-speed switch valve to control the pressure of the main and driven wheel hydraulic cylinder. Although the structure is simple, it can also realize the fast control of the CVT speed ratio and clamping force, but the speed ratio control hydraulic circuit and the clamping force control hydraulic circuit of the device It is a completely independent hydraulic circuit, without considering the coupling effect of the speed ratio control circuit and the clamping force control circuit; the fourth device uses constant pump, pilot pump and HSV high-speed switching valve to control the clamping force control circuit and speed ratio of CVT The control circuit can improve the control accuracy and response speed of the CVT, but the speed ratio control hydraulic circuit and the clamping force control hydraulic circuit of this device are also completely independent hydraulic circuits, and the relationship between the speed ratio control circuit and the clamping force control circuit is not considered. Coupling effect, and the HSV high-speed switching valve used in this device is very expensive to manufacture and very difficult to manufacture, so it is difficult to carry out mass production

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