At present, some electromechanical integrated clutch actuating system products have been put on the market, but the cost is high and the performance is unstable. Based on the current problems of clutch actuators, the main research direction of this paper is to design a low-cost, high-efficiency clutch actuator.
The traditional MT uses a hydraulic operating mechanism to push the hydraulic oil in the clutch master cylinder through the connecting rod connected by the pedal, thereby pushing the push rod or CSC piston of the clutch slave cylinder to realize the coupling and separation of the clutch. The traditional AT, AMT and DCT pump oil through the oil pump, and the hydraulic oil is distributed by the solenoid valve through the oil circuit to push the piston to compress or separate the pressure plate and the driven plate; push the release fork to drive the release bearing to be compressed by the diaphragm spring or to release the clutch The pressure plate and the clutch driven plate realize the coupling or separation of the clutch.
The clutch actuator of the traditional MT needs to cooperate with the operation of the accelerator pedal, the brake pedal and the shift lever, and it is easy to get tired after driving for a long time; when the clutch friction plate is worn, the pedal stroke will be offset, and it is difficult to achieve precise control by manual operation. lead to increased clutch wear. When the clutch friction plate is about to reach the limit of its life, the clutch coupling will become unstable, causing the whole vehicle to shake or the power to decrease, affecting the driving experience. The hydraulic system used by traditional AT, AMT and DCT, in order to achieve precise control, the solenoid valve has high manufacturing precision and small matching clearance, so the requirements for the cleanliness of the parts are high, and the manufacturing of the parts is difficult. When arranging the valve plate oil circuit, it is necessary to comprehensively consider the clutch control oil circuit and the shift oil circuit. The design is difficult, the structure is relatively complex, and the occupied volume is large, so the cost of the actuator will be high.
Aiming at the problems of traditional clutch actuators, an electromechanical integrated clutch actuator is developed. This automatic clutch actuator is mainly composed of control system, drive mechanism, actuator and other components. The combination of two sets of mechatronic clutch actuators can be used to drive the dual clutch of the DCT.
1. The driving mechanism includes: electric motor, transmission gear pair, screw nut pair and main hydraulic cylinder. The rotary motion of the motor is converted into the linear motion of the piston of the main hydraulic cylinder through the deceleration and torque increase of the gear pair and the motion of the screw nut pair.
2. The actuator includes: main hydraulic cylinder piston, internal and external CSC (single-cylinder CSC can be used for AMT), internal and external clutch (single clutch can be used when AMT is used), the movement of the main hydraulic cylinder piston is transmitted to the inside and outside through the oil CSC, respectively perform the actions of opening, closing and sliding of the inner and outer clutches.
3. The control system mainly includes the following components: TCU, pressure sensor, displacement sensor and target magnet. The TCU sends a rotation signal to the motor according to the judgment condition, the displacement sensor feeds back the motion termination position, and the pressure sensor feeds back the execution pressure. Find the coupling point of the clutch through self-learning, and carry out accurate control of the clutch through algorithm calculation.
4. Other components include: support bearing, exhaust valve for exhaust, oil replenishment device, anti-rotation pin of the lead screw, etc., to realize the functions of removing air in the oil, compensating for the loss of oil, and preventing the circumferential rotation of the lead screw.
This new type of electromechanical integrated automatic clutch actuator has few system components and simple structure, which simplifies the oil circuit of the hydraulic system and reduces the use of solenoid valves. The reduced occupied volume of this module on the transmission assembly can reduce the requirements for the cleanliness of parts when applied to AMT and DCT, and also reduce the difficulty of system integration, which is beneficial to control costs. The control system of this new clutch actuator can read the signals of the pressure sensor and displacement sensor, so as to diagnose whether the actual working state conforms to the set value.