Valve Body: Description and Operation
NAG1 TRANSMISSIONELECTROHYDRAULIC UNIT
DESCRIPTION
The electrohydraulic control unit comprises the shift plate made from light alloy for the hydraulic control and an electrical control unit. The electrical control unit comprises of a supporting body made of plastic, into which the electrical components are assembled. The supporting body is mounted on the shift plate and screwed to it.
Strip conductors inserted into the supporting body make the connection between the electrical components and a plug connector. The connection to the wiring harness on the vehicle and the transmission control module (TCM) is produced via this 13-pin plug connector with a bayonet lock.
ELECTRICAL CONTROL UNIT
The electric valve control unit (7) (Fig. 88) consists of a plastic shell which houses the RPM sensors (1,12), regulating solenoid valves (3, 4), solenoid valves (5, 6, 10), the TCC solenoid valve (11), the park/neutral contact (9), and the transmission oil temperature sensor (8). Conductor tracks integrated into the shell connect the electric components to a plug connection (2). This 13-pin plug connection (2) establishes the connection to the vehicle-side cable harness and to the transmission control module (TCM). With the exception of the solenoid valves, all other electric components are fixed to the conductor tracks.
HYDRAULIC CONTROL UNIT
Working Pressure (Operating Pressure) (p-A)
The working pressure provides the pressure supply to the hydraulic control and the transmission shift elements. It is the highest hydraulic pressure in the entire hydraulic system. The working pressure is regulated at the working pressure regulating valve in relation to the load and gear. All other pressures required for the transmission control are derived from the working pressure.
Lubrication Pressure (p-Sm)
At the working pressure regulating valve surplus oil is diverted to the lubrication pressure regulating valve, from where it is used in regulated amounts to lubricate and cool the mechanical transmission components and the torque converter. Furthermore, the lubrication pressure (p-Sm) is also used to limit the pressure in the torque converter.
Shift Pressure (p-S)
The shift pressure is determined by the shift pressure regulating solenoid valve and the shift pressure regulating valve. The shift pressure: e Regulates the pressure in the activating shift element during the shift phase. e Determines together with the modulating pressure the pressure reduction at the deactivating shift element as regulated by the overlap regulating valve. e Initializes 2nd gear in limp-home mode.
Modulating Pressure (p-Mod)
The modulating pressure influences the size of the working pressure and determines together with the shift pressure the pressure regulated at the overlap regulating valve. The modulating pressure is regulated at the modulating pressure regulating solenoid valve, which is under regulating valve pressure. The modulating pressure is variable and relative to the engine load.
Regulating Valve Pressure (p-RV)
The regulating valve pressure is regulated at the regulating valve pressure regulating valve in relation to the working pressure (p-A) up to a maximum pressure of 8 bar (116 psi). It supplies the modulating pressure regulating solenoid valve, the shift pressure regulating solenoid valve and the shift valve pressure regulating valve.
Shift Valve Pressure (p-SV)
The shift valve pressure (p-SV) is derived from the regulating valve pressure (p-RV), is regulated at the shift valve pressure regulating valve and is then present at the:
^ 1-2 and 4-5 shift solenoid valve.
^ 3-4 shift solenoid valve.
^ 2-3 shift solenoid valve.
^ Torque converter lockup solenoid valve.
^ 3-4 and 2-3 shift pressure shift valve.
The shift valve pressure (p-SV) controls the command valves via the upshift/downshift solenoid valves.
Overlap Pressure (p-U)
The overlap pressure controls the shift component pressure reduction during a shift phase. The pressure in a shift element as it disengages is controlled during the shift phase depending on engine load (modulating pressure) and the pressure in the shift element as it engages. The adjusted pressure is inversely proportional to the transmission capability of the shift element being engaged (controlled overlap).
Working Pressure Regulating Valve (Operating Pressure)
The working pressure regulating valve (Fig. 89) is located in the valve housing of the shift plate. It regulates the primary pressure of the hydraulic system.
Torque Converter Lockup Clutch Regulating Valve
The torque converter lock-up clutch regulating valve (Fig. 90) is located in the valve housing of the electrohydraulic control module. The valve is responsible for the hydraulic control of the torque converter lockup clutch and distribution of the lubricating oil.
Overlap Regulating Valve
Each shift group is assigned one overlap regulating valve (Fig. 91). The 1-2 / 4-5 overlap regulating valve is installed in the shift valve housing; the 2-3 and 3-4 overlap regulating valves are installed in the valve housing. The overlap regulating valve regulates the pressure reduction during a shift phase.
Command Valve
Each shift group possesses one command valve (Fig. 92). The 1-2 / 4-5 and 2-3 command valves are installed in the shift valve housing; the 3-4 command valve is installed in the valve housing. The command valve switches the shift group from the stationary phase to the shift phase and back again.
Holding Pressure Shift Valve
Each shift group possesses one holding pressure shift valve (Fig. 93). The 1-2 / 4-5 and 2-3 holding pressure shift valves are installed in the shift valve housing; the 3-4 holding pressure shift valve is installed in the valve housing. The holding pressure shift valve allocates the working pressure to one actuator of a shift group.
Shift Pressure Shift Valve
Each shift group possesses one shift pressure shift valve (Fig. 94). The 1-2 / 4-5 and 2-3 shift pressure shift valves are installed in the shift valve housing; the 3-4 shift pressure shift valve is installed in the valve housing. It assigns the shift pressure (p-S) to the activating actuator and the overlap pressure (p-U) regulated by the overlap regulating valve to the deactivating actuator.
Lubrication Pressure Regulating Valve
The lubrication pressure regulating valve (Fig. 95) is located in the valve housing of the electrohydraulic control module. The valve controls the fluid to lubricate and cool the mechanical part of the transmission, and limits the pressure in the torque converter.
Shift Pressure Regulating Valve
The shift pressure regulating valve (Fig. 96) is located in the valve housing of the shift plate. It regulates the shift pressure (p-S).
Regulating Valve Pressure Regulating Valve
The regulating valve pressure regulating valve (Fig. 97) is located in the valve housing of the electrohydraulic control module. It regulates the regulating valve pressure (p-RV).
Shift Valve Pressure Regulating Valve
The shift valve pressure regulating valve (Fig. 98) is located in the valve housing of the electrohydraulic control module. It regulates the shift valve pressure (P-SV).
OPERATION
ELECTRICAL CONTROL UNIT
Signals from the transmission control module (TCM) are converted into hydraulic functions in the electric valve control unit (7) (Fig. 99). The RPM sensors (1, 12), starter interlock contact (9), and transmission oil temperature sensor (8) of the electric valve control unit (7) supply the TCM with input signals. The solenoid valves are controlled by the TCM and trigger the hydraulic functions.
HYDRAULIC CONTROL UNIT
Working Pressure Regulating Valve (Operating Pressure)
The working pressure (p-A) is regulated at the working pressure regulating valve (22) (Fig. 100) in relation to load (modulating pressure) and gear (K1 or K2 pressure). The spring in the working pressure regulating valve sets a minimum pressure level (basic pressure).
Torque Converter Lockup Clutch Regulating Valve
The torque converter lockup clutch regulating valve (6) (Fig. 101) regulates the torque converter lock-up clutch working pressure in relation to the torque converter clutch control pressure. According to the size of the working pressure, the torque converter lockup clutch is either Engaged, Disengaged, or Slipping. When the regulating valve (6) is in the lower position, lubricating oil flows through the torque converter and oil cooler (8) into the transmission (torque converter lockup clutch unpressurized). In its regulating position (slipping, torque converter lockup clutch pressurized), a reduced volume of lubricating oil flows through the annular passage (7) bypassing the torque converter and passing direct through the oil cooler into the transmission. The rest of the lubricating oil is directed via the throttle "a" into the torque converter in order to cool the torque converter lockup clutch.
Overlap Regulating Valve
During the shift phase the pressure (Fig. 102) in the deactivating shift actuator is regulated in relation to the engine load (modulating pressure) and the pressure in the activating actuator. The regulated pressure is inversely proportional to the transfer capacity of the activating shift actuator (regulated overlap).
Command Valve
When the end face is unpressurized (stationary phase), the working pressure is directed to the actuated shift element. If the end face of the command valve (Fig. 103) is subjected to the shift valve pressure (p-SV) (shift phase), then the shift pressure is switched to the activating element and the overlap pressure is switched to the deactivating element.
Shift Valve Holding Pressure
The holding pressure shift valve (Fig. 104) is actuated by the pressures present at the end face in the actuators and a spring. It assigns the working pressure to the actuator with the higher pressure (taking into account the spring force and the effective surface area). The other element of the shift group is then unpressurized. The valve switches over only during the shift phase and only at a certain pressure ratio between the overlap pressure (p-U) and the shift pressure (p-S).
Shift Pressure Shift Valve
When the multiple-disc brake B1 (3) is activated, the working pressure (pa) is applied to the end face of the 1-2 / 4-5 shift pressure shift valve (4) (Fig. 105) via the command valve (1). Its shift state is maintained during the shift phase by substituting the shift element pressure acting on its end face (and which is variable during the shift phase) with a corresponding constant pressure. When the multi-plate clutch K1 (2) is activated, the end face of the shift valve is unpressurized during the stationary and shift phases, so the shift state is maintained during the shift phase in this case too.
Lubrication Pressure Regulating Valve
At the working pressure regulating valve surplus oil is diverted to the lubrication pressure regulating valve (1) (Fig. 106), from where the lubrication pressure (p-Sm) is used in regulated amounts to supply the transmission lubrication system including the torque converter.
Shift Pressure Regulating Valve
The shift pressure is determined by the shift pressure regulating solenoid valve and the shift pressure regulating valve (3) (Fig. 107). In addition, pressure from the clutch K2 (1) is also present at the annular surface (2) of the shift pressure regulating valve (3). This reduces the shift pressure in 2nd gear.
Regulating Valve Pressure Regulating Valve
The regulating valve pressure (p-RV) is set at the regulating valve pressure regulating valve (1) (Fig. 108) in relation to the working pressure (p-A) as far as the maximum pressure.
Shift Valve Pressure Regulating Valve
The non-constant regulating valve pressure (p-RV) is regulated to a constant shift valve pressure (p-SV) at the shift valve pressure regulating valve (1) (Fig. 109) and is used to supply the 1-2 and 4-5 / 3-4 / 2-3 solenoid valves and the torque converter lockup clutch PWM solenoid valve.