Electronic Component Description
Electronic Component Description
Electronic Components
6 - A/Trans Auxiliary Fluid Pump Assembly
31 - A/Trans Manual Shift Shaft Position Switch Assembly
71 - Drive Motor (w/Generator) Assembly - 1st Position
88 - Drive Motor (w/Generator) Assembly - 2nd Position
307 - Control Solenoid (w/Body and TCM) Valve Assembly
447 - A/Trans Output Speed Sensor Assembly
Hybrid Transmission
The Hybrid transmission contains two electric drive motor with generator assemblies, 3 planetary gear sets, and 4 wet-plate clutches. The hybrid transmission can operate in either two electronically variable transmission (EVT) modes or one of four fixed gear ratios. The two permanent magnet electric motors are packaged within the transmission which is installed longitudinally in the vehicle. Three high voltage A/C cables, connected to each of the two motors, attach to transmission housing and are routed via rigid conduit around the transmission then transition to flexible cable at the attachment to the drive motor generator control module (DMGCM) Transmission fluid is used for hydraulic control and transmission component and motor cooling. An auxiliary oil pump is mounted externally to the transmission and provides oil pressure during engine-off Auto-Stop operation.
Drive Motor with Generator Assemblies
1 - Drive Motor with Generator Assembly 1
2 - Drive Motor with Generator Assembly 2
Two permanent magnet electric motors mounted inside the transmission enable engine cranking, transmission reverse, and two EVT modes of operation. The front, or motor 1 and the rear, or motor 2 each provide 60kW peak power. Both are actively cooled via transmission fluid and are encased in steel housings to facilitate transmission assembly. The front motor is used to start the engine and also react torque from the rear motor. The rear motor propels the vehicle when operating in full-electric mode with the engine off or in reverse. Motor speeds are controlled and monitored by position sensors internal to the motor housings. The drive motor generator position sensor is monitored by the motor control module (MCM). The MCM monitors the angular position, speed and direction of the drive motor generator based upon the signals of the resolver-type position sensor. The position sensor (or resolver) contains a drive coil, two driven coils and an irregular shaped metallic rotor. The metallic rotor is mechanically attached to the shaft of the drive motor generator. At ignition ON, the MCM outputs a 5 volt ac, 10 kHz excitation signal to the drive coil. The drive coil excitation signal creates a magnetic field surrounding the two driven coils and the irregular shaped rotor. The MCM then monitors the two driven coil circuits for a return signal. The position of the irregular shaped metallic rotor causes the magnetically-induced return signals of the driven coils to vary in size and shape. A comparison of the two driven coils signals allows the MCM to determine the exact angle, speed and direction of the drive motor generator. For more information on the drive motor function and system interaction refer to Drive Motor Generator Control Module Description and Operation (Description and Operation) and Drive Motor Battery System Description (Drive Motor Battery System Description).
Control Solenoid (W/Body and TCM) Valve Assembly
Control Solenoid (W/Body and TCM) Valve Assembly:
1 - Pressure Control (PC) Solenoid 2
2 - Pressure Control (PC) Solenoid 4
3 - Shift Solenoid (SS) 2
4 - 16 Pin Connector
5 - Line Pressure Control (PC) Solenoid
6 - Transmission Fluid Pressure (TFP) Switch 5
7 - Pressure Control (PC) Solenoid 6 -Not Used
8 - Pressure Control (PC) Solenoid 3
9 - Transmission Fluid Pressure (TFP) Switch 3
10 - Transmission Fluid Pressure (TFP) Switch 1
11 - Transmission Fluid Pressure (TFP) Switch 4
12 - Pressure Control (PC) Solenoid 5
13 - Shift Solenoid (SS) 1
The control solenoid (w/body and TCM) valve assembly contains the following components:
* Transmission control module (TCM)
* Clutch pressure control solenoids (Clutch PC Sol)
* Shift solenoids (SS)
* Line pressure control solenoid (Line PC Sol)
* Transmission fluid temperature sensor (TFT Sensor)
* TCM temperature sensor
* Power-up temperature sensor (not used)
* Transmission fluid pressure switches (TFP Sw)
These components are not serviced separately. The control solenoid (w/body and TCM) valve assembly utilizes a lead-frame system to connect these components electrically to the TCM. No wires are used for these components. The control solenoid (w/body and TCM) valve assembly bolts directly to the lower and upper valve body assemblies inside the transmission. The control solenoid (w/body and TCM) valve assembly connects to the engine harness 16-way connector via a pass-thru sleeve.
Auxiliary Transmission Fluid Pump
The auxiliary oil pump is driven by a 12V AC motor controlled by a dedicated auxiliary fluid pump control module that is mounted in the engine compartment. Control of the auxiliary fluid pump is managed by the HPCM, which communicates directly with the auxiliary fluid pump control module. The purpose of the auxiliary fluid pump is to supply oil to the transmission for lube, cooling and clutch application during Auto-stop when the engine is off and the main transmission pump is not operating. The auxiliary fluid pump is commanded on when propulsion is active, such as when the vehicle is in electric only or stopped at a traffic light.
Internal Mode Switch (IMS)
The internal mode switch (IMS) assembly is a dual sliding contact switch attached to the control valve body within the transmission. The nine outputs from the switch indicate which position is selected by the transmission manual shaft. Four outputs (A, B, C, P), are range selection inputs to the transmission control module (TCM). Five outputs (R1, R2, D1, D2, S) are direction selection inputs to the HPCM through the transmission 24-way connector. The input voltage at the modules is high when the switch is open and low when the switch is closed to ground. The state of each input is displayed on the scan tool as IMS Range and IMS Direction. The IMS Range input parameters represented are transmission range signal A, signal B, signal C and signal P. The IMS Direction input parameters represented are transmission direction signal R1, signal R2, signal D1, signal D2 and signal Start.
Output Speed Sensor (OSS)
The output speed sensor (OSS) assembly has 2 internal hall-effect type sensors, and is capable of sensing both speed and direction. The OSS mounts to the A/T rear case assembly and is connected to the control solenoid (w/body and TCM) valve assembly through a wire harness and connector. The sensor faces the hybrid direct, 2-3-4 clutch housing assembly machined teeth surface. The sensor receives 8.3-9.3 volts on the OSS supply voltage circuit from the transmission control module (TCM). As the output shaft rotates, the sensor produces a signal frequency based on the machined surface of the output shaft.
The two sensor elements in the OSS assembly are spaced approximately 1/2 a tooth apart.
* When the vehicle is moving in a forward direction, sensor A detects a particular tooth before sensor B.
* When the vehicle is moving in a reverse direction, sensor B detects a particular tooth before sensor A.
The electronics in the sensor combine the two signals and send a signal with a different pulse width. This signal is interpreted by the TCM for speed and direction and is transmitted through the GMLAN circuits to the engine control module (ECM) and the hybrid powertrain control module (HPCM). The ECM, HPCM, and TCM compare the OSS signal with the ABS wheel speed sensor signal. The HPCM also compares the output shaft direction with the drive motor 1 and drive motor 2 direction.
Hybrid Transmission Modes of Operation
Electric Launch
Upon the driver removing their foot from the brake pedal and depressing the accelerator, the vehicle will launch in electric-only mode. Hybrid Low 1-2 Clutch is locked and motor 2 provides output torque to the wheels. Under low speed driving conditions the vehicle operates in full-electric mode without starting the engine or using drive motor 1. DC power from the battery flows to the HPCM where it is converted into 3-phase AC power to drive motor 2. The auxiliary oil pump runs to provide oil to the transmission for lubrication and hydraulic control. The vehicle continues to operate in electric-only mode, until additional power is required to accelerate the vehicle. At that point the engine starts.
EVT Mode 1
After the engine is started the system operates in EVT Mode 1 which is used for low speed urban driving conditions. Utilizing an input split configuration, engine simultaneously drives motor 1 to both generate electricity to charge the hybrid battery and provide power through the mechanical gearing in the transmission to the wheels. The energy generated by drive motor 1 is stored in the battery while drive motor 2 draws battery energy to provide additional output torque. Depending on driving conditions the engine will operate in either 4 or 8-cylinder mode to optimize fuel consumption while maintaining output power requirements. Combining EVT operation with Active Fuel Management (AFM) allows the engine to operate in 4-cylinder mode over a wider range of operating conditions than a non-hybrid vehicle. EVT and AFM are synergistic technologies that enable greater fuel economy when combined together than when either technology is used independently. Drive motor 2 provides output power to augment the engine in 4-cylinder mode and drive motor 1 can be used to provide torque smoothing.
EVT Mode 2
As vehicle speed increases, the system shifts to EVT Mode-2. EVT Mode 2 uses a compound split configuration to transfer power through the transmission during higher speed operating conditions such as highway cruising. Similar to EVT Mode 1, engine power is used to both generate electricity through the motors and provide output torque via the mechanical gearing in the transmission. A synchronous shift point allows the 2-Mode transmission to shift between EVT Mode 1 and Mode 2 without changing speed.
Fixed Gear Operation
Fixed gear operation is achieved by selectively locking Clutches in the transmission to transmit engine power through a mechanical path without the use of the drive motors. Advantages of having fixed ratios include the ability to increase engine size without having to increase motor size and improved towing, climbing, and maximum acceleration performance which are particularly important. In fixed gear modes the drive motors can be used entirely for power assist, rather than partially to carry power through the transmission. Furthermore, the drive motors can be partially powered down during cruising conditions.
Regenerative Braking
Regenerative braking is enabled in both EVT Mode 1 and Mode 2. As the driver lifts their foot from the accelerator pedal and depresses the brake pedal the electric motors are used to decelerate the vehicle by applying negative torque to the output shaft and generate electricity thereby charging the battery. The 3-phase AC power generated by the motor is converted to high-voltage DC power in the HPCM and stored in the battery. The Hybrid Operating System coordinates requests for negative torque requests from the electronic brake module with electric motor and engine control functions.
Engine Start-Stop
As the driver depresses the accelerator pedal further, demanding increased vehicle acceleration, drive motor 1 is used to start the engine while the Hybrid Low 1-2 Clutch remains locked and motor 2 simultaneously provides output power to the wheels. During the engine start event motor 1 also provides active damping to reduce torque disturbances from engine cylinder firing pulses, and motor 2 is used to damp driveline disturbances. During this event the inverter draws DC power from the battery and converts it to AC power for both motors. They HPCM controls each motor's speed and power independently. The HPCM determines when to stop the engine and when to restart based on vehicle operating conditions and optimal hybrid battery power and fuel consumption. The engine is stopped at idle and during deceleration maneuvers to improve fuel economy.
Reverse
When the vehicle is placed in reverse the Hybrid Low 1-2 Clutch is locked and Motor 2 spins backwards and provides output torque to the wheels. When needed the engine starts and Motor 1 is used to charge the hybrid battery and DC power from the battery flows to the HPCM where it is converted into 3-phase AC power to drive motor 2.