Electronic shift control system for continuously variable transmission

Abstract

The application discloses a built-in electronic gear shifting control system of a continuously variable transmission, which comprises a clutch oil supply electromagnetic valve, a switching slide valve, a pressure reducing valve, a first switching electromagnetic valve, a second switching electromagnetic valve and a third switching electromagnetic valve, wherein the clutch pressure inlet is connected with the clutch oil supply electromagnetic valve, the D-gear clutch inlet is connected with a D-gear clutch, the R-gear clutch inlet is connected with an R-gear clutch, the inlets of the first, second and third switching electromagnetic valves are connected with the outlet of the pressure reducing valve, the outlet of the first switching electromagnetic valve is connected with a first inlet, the outlet of the second switching electromagnetic valve is connected with a second inlet, and the outlet of the clutch oil supply electromagnetic valve is connected with a clutch pressure inlet.The built-in electronic gear shifting control system of the continuously variable transmission has the advantages of simpler structure, more accurate control and higher safety.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of transmission, and particularly relates to a built-in electronic gear shifting control system of a continuously variable transmission. BACKGROUND

[0002] Traditional continuously variable transmissions all adopt mechanical control of gear shifting and mechanical parking, and need to control a gear shifting lever and a hand brake to realize gear switching and parking. The traditional gear switching mechanism and parking mechanism have high requirements for space arrangement. With the continuous development of automobile automation and intelligent technology, the demand for electronic gear shifting and automatic parking is more urgent. External electronic gear shifting can realize automatic gear shifting by adding a driving motor to the periphery of the transmission, but it needs certain arrangement space and high cost. The built-in electronic gear shifting and electronic parking can effectively reduce the arrangement space.

[0003] An existing built-in electronic gear shifting mechanism does not have a gear recognition device, and cannot perform failure protection when an electromagnetic valve or a spool fails (for example, the R gear appears due to failure in the D gear state). In addition, the clutch oil cavity is directly connected with the switching valve, and there is no buffer protection when the clutch returns, which will cause gear shifting impact.

[0004] The control of the oil circuit of another existing built-in electronic gear shifting mechanism is realized by a low-pressure electromagnetic valve and two regulating valves, and the switching of the gears is realized by three spools. Two position sensors are used to recognize the gears, the system control is relatively complex, and the manufacturing cost is high. SUMMARY

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application provides a built-in electronic gear shifting control system of a continuously variable transmission, and the purpose is to reduce the complexity of the system.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a built-in electronic gear shifting control system of a continuously variable transmission, comprising a clutch oil supply electromagnetic valve, a switching spool, a pressure reducing valve, a first on-off electromagnetic valve, a second on-off electromagnetic valve and a third on-off electromagnetic valve. The switching spool has a first oil inlet, a second oil inlet, a clutch pressure oil inlet, a D-gear clutch oil inlet and an R-gear clutch oil inlet. The clutch pressure oil inlet is connected with the clutch oil supply electromagnetic valve. The D-gear clutch oil inlet is connected with a D-gear clutch. The R-gear clutch oil inlet is connected with an R-gear clutch. The oil inlets of the first on-off electromagnetic valve, the second on-off electromagnetic valve and the third on-off electromagnetic valve are connected with the oil outlet of the pressure reducing valve. The oil outlet of the first on-off electromagnetic valve is connected with the first oil inlet. The oil outlet of the second on-off electromagnetic valve is connected with the second oil inlet. The oil outlet of the clutch oil supply electromagnetic valve is connected with the clutch pressure inlet.

[0007] The switching spool comprises a valve body, a shift spool and a limiting spool arranged inside the valve body, and a first elastic element arranged between the shift spool and the limiting spool, and a first oil inlet, a second oil inlet, a clutch pressure oil inlet, a D-gear clutch oil inlet and an R-gear clutch oil inlet arranged on the valve body.

[0008] The continuously variable transmission built-in electronic gear shifting control system further comprises a first position sensor for detecting the position of the shift spool to identify the current gear.

[0009] The clutch oil supply electromagnetic valve is an NL type direct drive electromagnetic valve.

[0010] When the shift mechanism is engaged in the D-gear, the first and second switch electromagnetic valves are closed, the clutch pressure oil inlet is communicated with the D-gear clutch oil inlet, the clutch pressure oil inlet is not communicated with the R-gear clutch oil inlet, the R-gear clutch oil inlet is communicated with the second oil drain port, and the D-gear clutch oil inlet is not communicated with the third oil drain port.

[0011] When the shift mechanism is switched from the D-gear to other gears, the hydraulic oil flowing out of the D-gear clutch flows to the third oil drain port through the first throttle hole.

[0012] When the shift mechanism is engaged in the N-gear, the first and second switch electromagnetic valves are opened, the shift spool of the switching spool is located at the intermediate position, the clutch pressure oil inlet is not communicated with the D-gear clutch oil inlet, the clutch pressure oil inlet is not communicated with the R-gear clutch oil inlet, the R-gear clutch oil inlet is communicated with the second oil drain port, and the D-gear clutch oil inlet is communicated with the third oil drain port.

[0013] When the shift mechanism is engaged in the R-gear, the first switch electromagnetic valve is opened, the second switch electromagnetic valve is closed, the clutch pressure oil inlet is not communicated with the D-gear clutch oil inlet, the clutch pressure oil inlet is communicated with the R-gear clutch oil inlet, the R-gear clutch oil inlet is not communicated with the second oil drain port, and the D-gear clutch oil inlet is communicated with the third oil drain port.

[0014] The continuously variable transmission built-in electronic gear shifting control system has the advantages of simpler structure, more accurate control and higher safety, and can reduce the system complexity while meeting all the function modes of the built-in electronic gear shifting and electronic parking. BRIEF DESCRIPTION OF DRAWINGS

[0015] The present specification includes the following drawings, and the shown contents are as follows:

[0016] Figure 1 is a structural schematic view of the continuously variable transmission built-in electronic gear shifting control system of the present application;

[0017] Figure 2is a gear shifting schematic diagram;

[0018] In the figure, the marks are: 1, clutch oil supply solenoid valve; 2, second oil inlet; 3, valve body; 4, stop block; 5, limit valve core; 6, shift valve core; 7, R-gear clutch oil inlet; 8, first switching solenoid valve; 9, second switching solenoid valve; 10, pressure reducing valve; 11, first oil drain; 12, first elastic element; 13, first oil inlet; 14, second oil drain; 15, clutch pressure inlet; 16, D-gear clutch oil inlet; 17, third oil drain; 18, first position sensor; 19, D-gear clutch; 20, R-gear clutch; 21, electromagnetic actuator; 22, parking piston cavity; 23, oil drain; 24, second elastic element; 25, parking piston; 26, second position sensor; 27, third switching solenoid valve. DETAILED DESCRIPTION

[0019] The specific embodiments of the present application are further described below with reference to the drawings, by describing the embodiments, in order to help the skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present application, and to help its implementation.

[0020] As Figure 1 and Figure 2 shown, the present application provides an electronic shift control system built-in continuously variable transmission, comprising a clutch oil supply solenoid valve 1, a switching spool, a pressure reducing valve 10, a first switching solenoid valve 8, a second switching solenoid valve 9 and a third switching solenoid valve 27, the switching spool has a first oil inlet 13, a second oil inlet 2, a clutch pressure oil inlet, a D-gear clutch oil inlet 16, a R-gear clutch oil inlet 7, a first oil drain 11, a second oil drain 14 and a third oil drain 17, the clutch pressure oil inlet is connected with the clutch oil supply solenoid valve 1, the D-gear clutch oil inlet 16 is connected with the D-gear clutch, the R-gear clutch oil inlet 7 is connected with the R-gear clutch, the oil inlets of the first switching solenoid valve 8, the second switching solenoid valve 9 and the third switching solenoid valve 27 are connected with the oil outlet of the pressure reducing valve 10, the oil outlet of the first switching solenoid valve 8 is connected with the first oil inlet 13, the oil outlet of the second switching solenoid valve 9 is connected with the second oil inlet 2, the oil outlet of the third switching solenoid valve 27 is connected with the oil inlet of the parking piston cavity 22, and the oil outlet of the clutch oil supply solenoid valve 1 is connected with the clutch pressure inlet 15.

[0021] Specifically, as Figure 1 and Figure 2As shown, the switching spool valve includes a valve body 3, a shift valve core 6 and a limit valve core 5 disposed inside the valve body 3, and a first elastic element 12 disposed between the shift valve core 6 and the limit valve core 5. A first oil inlet 13, a second oil inlet 2, a clutch pressure oil inlet, a D-gear clutch oil inlet 16, and an R-gear clutch oil inlet 7 are disposed on the valve body 3. The shift valve core 6 and the limit valve core 5 are movably disposed within the inner cavity of the valve body 3. The first elastic element 12 is a cylindrical helical spring and is a compression spring. The shift valve core 6 and the limit valve core 5 are coaxially arranged, and the first elastic element 12 is sandwiched between the shift valve core 6 and the limit valve core 5. The first elastic element 12 is used for resetting the shift valve core 6 and the limit valve core 5. The first oil inlet 13, the first oil outlet 11, the second oil inlet 2, the second oil outlet 14, the clutch pressure oil inlet, the clutch inlet for disengaging from D gear 16, and the third oil outlet 17 are arranged sequentially along the length of the valve body 3. The inner cavity of the valve body 3 has five stepped holes of different diameters, decreasing in size from left to right, used to limit the movement of valve cores of different diameters. It is equipped with three oil inlets, two oil outlets, and three oil outlets.

[0022] The shift valve core 6 has three working positions: D position, R position, and intermediate position, with the intermediate position located between the D and R positions. When the shift mechanism is engaged in D gear, the shift valve core 6 switches to the D position; when the shift mechanism is engaged in R gear, the shift valve core 6 switches to the R position; and when the shift mechanism is engaged in N gear, the shift valve core 6 switches to the intermediate position.

[0023] like Figure 1 As shown, the continuously variable transmission (CVT) built-in electronic shift control system of the present invention also includes a first position sensor 18 for detecting the position of the shift valve core 6 to identify the current gear and ensure that the position of the shift valve core 6 is consistent with the driver's intention. Figure 1 This improves driving safety. The first position sensor 18 is fixedly mounted on the valve body 3 and is electrically connected to the TCU (Transmission Control Unit).

[0024] like Figure 1 As shown, the electronic parking mechanism includes an electromagnetic actuator 21, a parking piston chamber 22, a second elastic element 24, a parking piston 25, and a second position sensor 26. The parking piston 25 is movably disposed in the parking piston chamber 22. The second elastic element 24 is a compression spring that applies an elastic force to the parking piston 25 to reset it. The electromagnetic actuator 21 is used to perform the parking action.

[0025] like Figure 1As shown, the oil outlet of the pressure reducing valve 10 is connected to the oil inlet of the first on-off solenoid valve 8, the oil inlet of the second on-off solenoid valve 9 and the oil inlet of the third on-off solenoid valve 27, the oil outlets of the first on-off solenoid valve 8 and the second on-off solenoid valve 9 are connected to the first oil inlet 13 and the second oil inlet 2 on the valve body 3 respectively, and the oil outlet of the third on-off solenoid valve 27 is connected to the oil inlet of the parking piston cavity 22 of the electronic parking mechanism.

[0026] Preferably, the clutch oil supply solenoid valve 1 is an NL type direct drive solenoid valve. The NL direct drive solenoid valve is used to control the clutch pressure, which has high control accuracy and can protect the gearbox by using clutch slip when the torque suddenly changes. When the solenoid valve fails or the TCU is powered off, the whole vehicle is in N gear.

[0027] As shown in Figure 1 and Figure 2 When the shift mechanism is engaged in D gear, the first on-off solenoid valve 8 and the second on-off solenoid valve 9 are closed, the shift spool 6 is in the D gear position, the clutch pressure oil inlet is communicated with the D gear clutch oil inlet 16, the clutch pressure oil inlet is not communicated with the R gear clutch oil inlet 7, the R gear clutch oil inlet 7 is communicated with the second oil drain 14, and the D gear clutch oil inlet 16 is not communicated with the third oil drain 17.

[0028] As shown in Figure 1 and Figure 2 When the shift mechanism is engaged in D gear, the first position sensor 18 sends a first position signal to the TCU, and the TCU sends a command to the clutch oil supply solenoid valve 1 after receiving the first position signal, to control the clutch oil supply solenoid valve 1 to open. At this time, under the action of the spring force generated by the first elastic element 12, the shift spool 6 switches to the D gear position, so that the clutch pressure oil inlet is communicated with the D gear clutch oil inlet 16, and the oil pressure enters the piston cavity of the D gear clutch, causing the D gear clutch to engage and start transmitting torque.

[0029] As shown in Figure 1 When the shift mechanism is switched from D gear to other gears, the D gear clutch oil inlet 16 is communicated with the third oil drain 17, and the hydraulic oil flowing out of the D gear clutch flows to the valve body 3 through the first throttle hole, and is discharged through the third oil drain 17. The first throttle hole is arranged in the oil path connecting the valve body 3 and the D gear clutch, and is used to control the oil drain speed of the hydraulic oil, so as to ensure that the clutch does not immediately disengage during the shifting process, control the D gear clutch to disengage slowly, and effectively avoid shifting impact and increase shifting reliability.

[0030] As shown in Figure 1 and Figure 2As shown in FIG. 1 and FIG. 2, when the shift mechanism is engaged in N gear, the first switch solenoid valve 8 and the second switch solenoid valve 9 are opened, the clutch oil supply solenoid valve 1 is closed, the shift spool 6 of the switching spool is in the intermediate position, the clutch pressure inlet is not communicated with the D-gear clutch inlet 16, the clutch pressure inlet is not communicated with the R-gear clutch inlet 7, the R-gear clutch inlet 7 is communicated with the second oil drain 14, and the D-gear clutch inlet 16 is communicated with the third oil drain 17.

[0031] As shown in FIG. 1 and FIG. 2, when the shift mechanism is engaged in N gear, the first switch solenoid valve 8 and the second switch solenoid valve 9 are opened, the clutch oil supply solenoid valve 1 is closed, the shift spool 6 of the switching spool is in the intermediate position, the clutch pressure inlet is not communicated with the D-gear clutch inlet 16, the clutch pressure inlet is not communicated with the R-gear clutch inlet 7, the R-gear clutch inlet 7 is communicated with the second oil drain 14, and the D-gear clutch inlet 16 is communicated with the third oil drain 17. Figure 1 Figure 2 As shown in FIG. 1 and FIG. 2, when the shift mechanism is engaged in N gear, the first switch solenoid valve 8 and the second switch solenoid valve 9 are opened, the clutch oil supply solenoid valve 1 is closed, the shift spool 6 of the switching spool is in the intermediate position, the clutch pressure inlet is not communicated with the D-gear clutch inlet 16, the clutch pressure inlet is not communicated with the R-gear clutch inlet 7, the R-gear clutch inlet 7 is communicated with the second oil drain 14, and the D-gear clutch inlet 16 is communicated with the third oil drain 17.

[0032] As shown in FIG. 1 and FIG. 2, when the shift mechanism is engaged in N gear, the first switch solenoid valve 8 and the second switch solenoid valve 9 are opened, the clutch oil supply solenoid valve 1 is closed, the shift spool 6 of the switching spool is in the intermediate position, the clutch pressure inlet is not communicated with the D-gear clutch inlet 16, the clutch pressure inlet is not communicated with the R-gear clutch inlet 7, the R-gear clutch inlet 7 is communicated with the second oil drain 14, and the D-gear clutch inlet 16 is communicated with the third oil drain 17. Figure 1 Figure 2 As shown in FIG. 1 and FIG. 2, when the shift mechanism is engaged in N gear, the first switch solenoid valve 8 and the second switch solenoid valve 9 are opened, the clutch oil supply solenoid valve 1 is closed, the shift spool 6 of the switching spool is in the intermediate position, the clutch pressure inlet is not communicated with the D-gear clutch inlet 16, the clutch pressure inlet is not communicated with the R-gear clutch inlet 7, the R-gear clutch inlet 7 is communicated with the second oil drain 14, and the D-gear clutch inlet 16 is communicated with the third oil drain 17.

[0033] As shown in FIG. 1 and FIG. 2, when the shift mechanism is engaged in N gear, the first switch solenoid valve 8 and the second switch solenoid valve 9 are opened, the clutch oil supply solenoid valve 1 is closed, the shift spool 6 of the switching spool is in the intermediate position, the clutch pressure inlet is not communicated with the D-gear clutch inlet 16, the clutch pressure inlet is not communicated with the R-gear clutch inlet 7, the R-gear clutch inlet 7 is communicated with the second oil drain 14, and the D-gear clutch inlet 16 is communicated with the third oil drain 17. Figure 1 Figure 2 As shown in FIG. 1 and FIG. 2, when the shift mechanism is engaged in N gear, the first switch solenoid valve 8 and the second switch solenoid valve 9 are opened, the clutch oil supply solenoid valve 1 is closed, the shift spool 6 of the switching spool is in the intermediate position, the clutch pressure inlet is not communicated with the D-gear clutch inlet 16, the clutch pressure inlet is not communicated with the R-gear clutch inlet 7, the R-gear clutch inlet 7 is communicated with the second oil drain 14, and the D-gear clutch inlet 16 is communicated with the third oil drain 17.

[0034] When switching from D gear to N gear or from R gear to N gear, the oil drain oil way is connected with the one-way valve, the one-way valve is closed during oil drain, and the oil drain time is controlled by closing the one-way valve, thereby avoiding gear shift shock caused by too fast return of the clutch during gear shift.​​​

[0035] As Figure 1 shown, when the shift mechanism is engaged in P, the electromagnetic actuator 21 is powered, and under the spring force generated by the second elastic element 24, the parking piston 25 moves to the left, the parking piston 25 pushes the parking rod into the parking groove, realizing the parking brake, after the second position sensor 26 detects that the parking piston 25 moves to the P position, sends a signal to the TCU, the TCU controls the electromagnetic actuator 21 to be powered off, and locks the parking piston 25. When the P is unlocked, the electromagnetic actuator 21 is powered, the third switch electromagnetic valve 27 is powered, the hydraulic oil enters the parking piston cavity 22 through the third switch electromagnetic valve 27, and pushes the parking piston 25 to move, after the second position sensor 26 detects that the parking piston 25 moves to the P unlocking position, sends a signal to the TCU, the TCU controls the electromagnetic actuator 21 to be powered off, and locks the parking piston 25, and the TCU controls the third switch electromagnetic valve 27 to be powered off.

[0036] The continuously variable transmission built-in electronic gear shifting control system of the application is integrated in the hydraulic valve body 3 assembly, integrated design, more compact structure, and simple oil circuit design, lower cost.

[0037] The application adopts the built-in electronic gear shifting mechanism integrated in the hydraulic module, uses electric signal control to realize gear switching (D / N / R), is more compact in arrangement, and is higher in automation and intelligence.

[0038] The application adopts the position sensor to monitor the gear, ensures that the position of the switched gear is consistent with the intention of the driver, avoids misengaging gears even when the on-off electromagnetic valve fails, and improves the safety of the vehicle.

[0039] The application is described above in conjunction with the drawings. Obviously, the specific implementation of the application is not limited by the above method. As long as various non-essential improvements are made by using the method concept and technical solution of the application, or the above-mentioned concept and technical solution of the application is directly applied to other occasions without improvement, they are all within the protection scope of the application.

Claims

1. An electronic shift control system for a continuously variable transmission, characterized by: The clutch oil supply electromagnetic valve, the switching spool, the pressure reducing valve, the first switch electromagnetic valve, the second switch electromagnetic valve and the third switch electromagnetic valve are included, the switching spool has a first oil inlet, a second oil inlet, a clutch pressure oil inlet, a D-gear clutch oil inlet and an R-gear clutch oil inlet, the clutch pressure oil inlet is connected with the clutch oil supply electromagnetic valve, the D-gear clutch oil inlet is connected with a D-gear clutch, the R-gear clutch oil inlet is connected with an R-gear clutch, the oil inlets of the first switch electromagnetic valve, the second switch electromagnetic valve and the third switch electromagnetic valve are connected with the oil outlet of the pressure reducing valve, the oil outlet of the first switch electromagnetic valve is connected with the first oil inlet, the oil outlet of the second switch electromagnetic valve is connected with the second oil inlet, and the oil outlet of the clutch oil supply electromagnetic valve is connected with the clutch pressure inlet; The switching spool includes a valve body, a shift spool and a limiting spool arranged in the valve body, and a first elastic element arranged between the shift spool and the limiting spool, the first oil inlet, the second oil inlet, the clutch pressure oil inlet, the D-gear clutch oil inlet and the R-gear clutch oil inlet are arranged on the valve body; The shift spool and the limiting spool are movably arranged in the inner cavity of the valve body, and are coaxially arranged, the first elastic element is clamped between the shift spool and the limiting spool, and is used for resetting the shift spool and the limiting spool, the first oil inlet, the first oil outlet, the second oil inlet, the second oil outlet, the clutch pressure oil inlet, the D-gear clutch oil inlet and the third oil outlet are arranged along the length direction of the valve body; The shift spool has three working positions, which are a D-gear position, an R-gear position and an intermediate position, and the intermediate position is between the D-gear position and the R-gear position, when the shift mechanism is engaged in the D-gear, the shift spool is switched to the D-gear position, when the shift mechanism is engaged in the R-gear, the shift spool is switched to the R-gear position, and when the shift mechanism is engaged in the N-gear, the shift spool is switched to the intermediate position; The built-in electronic gear shifting control system of the continuously variable transmission further includes a first position sensor for detecting the position of the shift spool, the first position sensor is fixedly arranged on the valve body, and the first position sensor is electrically connected with the TCU; The electronic parking mechanism includes an electromagnetic actuator, a parking piston cavity, a second elastic element, a parking piston and a second position sensor, the parking piston is movably arranged in the parking piston cavity, the second elastic element is a compression spring, the second elastic element applies an elastic force to the parking piston, and is used for resetting the parking piston, and the electromagnetic actuator is used for performing a parking action; The oil outlet of the pressure reducing valve is connected with the oil inlets of the first switch electromagnetic valve, the second switch electromagnetic valve and the third switch electromagnetic valve, the oil outlets of the first switch electromagnetic valve and the second switch electromagnetic valve are connected with the first oil inlet and the second oil inlet on the valve body respectively, and the oil outlet of the third switch electromagnetic valve is connected with the oil inlet of the parking piston cavity of the electronic parking mechanism; The inner cavity of the valve body has five stepped holes with different diameters, which are sequentially reduced from left to right, and are used for limiting the valve spools with different diameters, and the valve body is provided with three oil inlets, two oil outlets and three oil outlets; The clutch oil supply electromagnetic valve is an NL type direct drive electromagnetic valve. When the shift mechanism is engaged in D, the first and second switch solenoid valves are closed, the shift valve spool is in the D position, the clutch pressure inlet is communicated with the D clutch inlet, the clutch pressure inlet is not communicated with the R clutch inlet, the R clutch inlet is communicated with the second drain port, and the D clutch inlet is not communicated with the third drain port; When the shift mechanism is engaged in D, the first position sensor sends a first position signal to the TCU, and the TCU sends a command to the clutch supply solenoid valve after receiving the first position signal, to control the clutch supply solenoid valve to open. At this time, under the action of the spring force generated by the first elastic element, the shift valve spool switches to the D position, so that the clutch pressure inlet is communicated with the D clutch inlet. After the oil pressure enters the piston cavity of the D clutch, the D clutch is engaged to start transmitting torque. When the shift mechanism is switched from D to other gears, the D clutch inlet is communicated with the third drain port, and the hydraulic oil flowing out of the D clutch flows to the valve body through the first throttle hole and is discharged through the third drain port. When the shift mechanism is engaged in N, the first and second switch solenoid valves are opened, the clutch supply solenoid valve is closed, the shift valve spool of the switching spool is in the intermediate position, the clutch pressure inlet is not communicated with the D clutch inlet, the clutch pressure inlet is not communicated with the R clutch inlet, the R clutch inlet is communicated with the second drain port, and the D clutch inlet is communicated with the third drain port. When the shift mechanism is engaged in N, the first and second switch solenoid valves are opened, and hydraulic oil enters the valve body through the first and second switch solenoid valves. At this time, under the combined action of the spring force generated by the first elastic element and the oil pressure from the first and second switch solenoid valves, the shift valve spool switches to the intermediate position, the first elastic element is compressed, the first position sensor sends a second position signal to the TCU, and the TCU sends a command to the clutch supply solenoid valve after receiving the second position signal, to control the clutch supply solenoid valve to close, so that the D clutch and the R clutch have no oil pressure. When the shift mechanism is engaged in R, the first switch solenoid valve is opened, the second switch solenoid valve is closed, the clutch pressure inlet is not communicated with the D clutch inlet, the clutch pressure inlet is communicated with the R clutch inlet, the R clutch inlet is not communicated with the second drain port, and the D clutch inlet is communicated with the third drain port. When the shift mechanism is engaged in R, the first switch solenoid valve is opened, the second switch solenoid valve is closed, and hydraulic oil enters the valve body through the first switch solenoid valve. At this time, under the combined action of the spring force generated by the first elastic element and the oil pressure from the first switch solenoid valve, the shift valve spool switches to the R position, the limit valve spool is reset, the first elastic element is compressed, the first position sensor sends a third position signal to the TCU, and the TCU sends a command to the clutch supply solenoid valve after receiving the third position signal, to control the clutch supply solenoid valve to open, so that the clutch pressure inlet is communicated with the R clutch inlet. After the oil pressure enters the piston cavity of the R clutch, the R clutch is engaged to start transmitting torque.

2. The built-in electronic shift control system for a continuously variable transmission according to claim 1, characterized by: The clutch oil supply electromagnetic valve is an NL type direct drive electromagnetic valve.

3. The built-in electronic shift control system for a continuously variable transmission according to claim 1, characterized by: The first elastic element is a cylindrical coil spring and is a compression spring.

4. The built-in electronic shift control system for a continuously variable transmission according to claim 1, characterized by: The inner cavity of the valve body has five stepped holes with different diameters, which are sequentially reduced from left to right, are used for cooperating with valve cores with different diameters to limit, are provided with three oil inlet ports, two oil outlet ports and three oil drain ports.

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