FUNCTION OF MAIN COMPONENTS
The main components of the K312 CVT system are as follows:
| Component | Function | |
|---|---|---|
| Continuously Variable Transaxle Assembly | Shift Solenoid Valve SC | Used to switch control of the shift solenoid valve SLU between forward and reverse clutch control and lock-up clutch control. |
| Shift Solenoid Valve SL | ||
| Shift Solenoid Valve SLU | Performs forward and reverse clutch control or lock-up clutch control depending on the state of the shift solenoid valves SC and SL. | |
| Shift Solenoid Valve SLP | Controls the oil pressure of the primary pulley. | |
| Shift Solenoid Valve SLS | Controls the oil pressure of the secondary pulley. | |
| Transmission Revolution Sensor (NIN) | Detects the primary pulley speed. | |
| Transmission Revolution Sensor (NOUT) | Detects the secondary pulley speed. | |
| Transmission Revolution Sensor (NT) | Detects the input turbine speed. | |
| CVT Fluid Temperature Sensor | Detects the CVT fluid temperature. | |
| Oil Pressure Sensor | Detects the oil pressure for belt clamping force. | |
| Transmission Oil Cooler | Helps warm up the CVT fluid immediately after the engine is started and then performs as a oil cooler during normal driving. | |
| E. F. I. Engine Coolant Temperature Sensor | Detects the engine coolant temperature. | |
| Accelerator Pedal Sensor Assembly | Detects the accelerator pedal opening angle. | |
| Throttle Position Sensor | Detects the opening angle of the throttle valve. | |
| Stop Light Switch Assembly | Detects the brake pedal depressing signal. | |
| Park/Neutral Position Switch Assembly | Detects the shift lever position. | |
| Transmission Control Switch |
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| Shift Paddle Switch (Transmission Shift Switch Assembly)* | Detects the driver's upshift or downshift request. | |
| Pattern Select Switch Assembly | Detects that the driving mode is in the sport mode. | |
| Combination Meter Assembly | Shift Position Indicator | Indicates the shift lever position and shift range. |
| Sport Mode Indicator | Illuminates when the pattern select switch assembly is pressed and informs the driver that sport mode is active. | |
| MIL | Illuminates or blinks to alert the driver that the ECM has detected a malfunction. | |
| Buzzer | Sounds when shift-down operation is rejected in M mode. | |
| ECM |
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| Yaw Rate and Acceleration Sensor (Airbag Sensor Assembly | Detects the angle of inclination of the vehicle. | |
| Brake Actuator Assembly | Skid Control ECU |
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| Air Conditioning Amplifier Assembly | Transmits the operating state of the air conditioning system to the ECM. | |
| Engine Stop and Start ECU | Sends signals to each control computer to perform the engine start and stop control and the slope start assistant control. | |
| Backup Boost Converter | Supplies battery voltage to the oil pump with motor assembly. | |
| Oil Pump with Motor Assembly | Maintains CVT oil pressure during idle stop. It also contains the oil pump motor driver. | |
| Oil Pump Motor Driver | Controls the output of the oil pump with motor assembly. | |
*: Models with shift paddle switch (transmission shift switch assembly)
The main components of the shift lock system are as follows:
| Component | Function | |
|---|---|---|
| Shift Lock Control Unit | Shift Lock Solenoid | Locks the shift lever in P. |
| P Detection Switch | Detects if the shift lever is in P. | |
| Stop Light Switch Assembly | Detects if the brake pedal is depressed. | |
| Shift Lock Control ECU Assembly | Controls the shift lock solenoid based on signals from each switch. | |
SYSTEM CONTROL
Control List
The electronic control system of the K312 CVT consists of the controls listed below.
| Control | Outline |
|---|---|
| Engine - CVT Integrated Control | Effects coordinate control of the CVT system and engine control system to ensure both smooth and powerful driving that excels in shift response and fuel economy. |
| Automatic Shift Control | Optimally controls the pulley ratio and shifting speed to suit the driver's intentions and driving conditions based on signals from various sensors and switches. |
| Acceleration Improvement Control | |
| 7-speed Sport Sequential Shiftmatic | |
| Neutral Control | When the vehicle is stopped, the driving force to the transaxle is shut off to improve fuel economy. |
| Shift Control in Uphill/Downhill Traveling | Controls to restrict the upshifts or to provide appropriate engine braking by using the ECM to determine whether the vehicle is traveling uphill or downhill. |
| Lock-up Control | The ECM sends a current to shift solenoid valve SC, SL, and SLU based on the throttle position sensor signal and vehicle speed signal, and engages or disengages the lock-up clutch. |
| Flex Lock-up Control | |
| Oil Pump Motor Control | Controls the oil pump motor to regulate the oil pressure to the optimum level so that the vehicle can start off smoothly. |
Engine - CVT Integrated Control
To effect fine-tuned control in accordance with driving conditions, various signals are exchanged between the engine control system and the CVT system. As a result, both smooth and powerful driving that excels in shift response and fuel economy has been achieved.
Speed Ratio Control (Shift Control)
The ECM calculates the target primary pulley revolution speed in accordance with the accelerator pedal position signal, vehicle speed signal, and stop light switch signal, in order to attain an optimal pulley ratio and shifting speed. To allow the actual primary pulley speed (acquired from the primary speed sensor) to match the target primary pulley speed, the ECM actuates shift solenoid valves SLP and SLS in order to control the pressure of primary pulley and secondary pulley. As a result, optimal pulley ratio and shifting speed have been achieved.
When the shift lever is in D, the system effects engine integrated control to optimize fuel economy characteristics and driving performance.
The sport mode limits the shift range for the acceleration side and maintains the primary pulley speed at high speeds. This produces a moderate engine braking force and provides an excellent shift response.
When the shift lever is in M, the shift characteristic is as shown below. The system will upshift automatically when the vehicle reaches the set speed during acceleration.
Acceleration Improvement Control
The driver's acceleration demand is judged from the change of vehicle speed and change of accelerator pedal input.
When starting off or accelerating, the engine speed and the vehicle speed are controlled to produce a linear feeling, improving the acceleration feeling. In addition, during acceleration, upshifts are performed. These upshifts prevent a stagnant feeling during acceleration as well as enabling the linear acceleration feeling.
Shift Control in Uphill/Downhill Traveling
The ECM determines that the vehicle is driving uphill or downhill based on the accelerator pedal position sensor signal and the vehicle speed signal. During uphill driving, it limits upshifting to achieve smooth driving. During downhill driving, it downshifts upon detecting brake pedal operation, in order to provide moderate engine braking.
The actual acceleration calculated from the vehicle speed signal is compared with the reference acceleration (based on level road travel) stored in the ECM to determine uphill or downhill travel.
| *a | Uphill | *b | Downhill |
| *c | Smaller | *d | Greater |
|
Reference acceleration | |
Actual acceleration |
Lock-up Control
The lock-up operation range has been expanded from that of the previous continuously variable transaxle, thus enabling control to start from low speeds.
The lock-up operation range during deceleration has been expanded to the low-speed range. This expands the fuel cut range and achieves excellent fuel economy.
| *1 | Lock-up Off |
| *2 | Throttle Opening Angle |
| *3 | Lock-up On |
| *4 | Vehicle Speed |
Flex lock-up Control
In order to improve the transmission efficiency and also the fuel economy, the linear solenoid (SLU) for lock-up engagement pressure control is employed to deliver flex lock-up control that can provide more precise control than that of the conventional lock-up clutch mechanism.
The flex lock-up control consists of flex start control and flex lock-up control at deceleration.
The flex start control aggressively operates the lock-up clutch during start-off to increase the transmission efficiency, as a result, the engine can run in its most efficient operating range.
Flex lock-up control during deceleration is used to expand the fuel-cut range. It operates the lock-up clutch over the low vehicle speed range when the vehicle decelerates so that minimal speed difference between the engine speed and turbine speed can be maintained.
Neutral Control
While the vehicle is stopped with the shift lever in D, by disconnecting the engine and CVT (releasing the forward clutch halfway), engine load is reduced. This improves fuel economy. However, if a certain gradient or higher is detected by forward and backward acceleration signals , the neutral control will not be implemented.
Oil Pump Motor Control
Because the engine stop and start ECU operates the oil pump with motor assembly at the time of idle stop, the CVT oil pressure is secured, enabling smooth vehicle start.
Oil Pump with Motor Assembly Operation Control
The oil pump with motor assembly is operated according to the engine stop signal.
After engine automatic start, operation of the oil pump with motor assembly stops either when the engine speed exceeds a set value or when driving force is generated.
| Shift Position | P | R | N | D | M |
|---|---|---|---|---|---|
| Brake ON (applied) | O | - | O | O | O |
| Brake OFF (not applied) | O | - | O | - | - |
| Condition | Remarks | |
|---|---|---|
| CVT Oil Temperature | 25°C to 110°C (77°F to 230°F) | Detected from the oil temperature sensor in the CVT |
Stand-by Pressure Learning Control
Performs learning control to optimally control the oil pressure of the oil pump with motor assembly at the time of stand-by.
Fail-safe
This fail-safe function minimizes the loss of operability when an abnormality occurs in a sensor or shift solenoid valve. For details, refer to the Repair Manual.
Diagnosis
When the ECM detects a malfunction, the ECM records the malfunction and memorizes the information related to the fault. Furthermore, the ECM illuminates or blinks the Malfunction Indicator Lamp (MIL) in the combination meter assembly to inform the driver.
The ECM will also store the Diagnostic Trouble Codes (DTCs) of the malfunctions. The DTCs stored in the ECM are output to the Global TechStream (GTS) via the ECM and the DLC3. For details, refer to the Repair Manual.
Tech Tips
To clear a DTC that is stored in the ECM, use the Global TechStream (GTS) or disconnect the cable from the battery terminal for 1 minute or longer.
FUNCTION
7-speed Sport Sequential Shiftmatic
The driver can select the desired shift range by moving the shift lever to "+" (forwards) or to "-" (backwards) while shift lever is in M (M mode). Also, the shift paddle switch (transmission shift switch assembly) is used*, which enable changing the shift range while the driver is holding the steering wheel. Thus, the driver is able to shift gears with a manual-like feel.
*: Models with shift paddle switch (transmission shift switch assembly)
When the shift lever is in D (D mode), the driver can momentarily select a desired shift range (M mode) by operating the shift paddle switch (transmission shift switch assembly). *
Automatic shifting (D mode) will be reinstated under the following conditions:
The driver continues to push the shift paddle switch (transmission shift switch assembly) in the "+" direction longer than a predetermined length of time.
The driver depresses the accelerator pedal longer than a predetermined length of time while the transmission remains in the same shift range.
The vehicle has stopped.
*: Models with shift paddle switch (transmission shift switch assembly)
| *a | 5th in M Mode |
| *b | 5th in D Mode |
| *c | M Mode |
In M mode, the transmission automatically upshifts or downshifts under the following conditions:
| Condition | System Control |
|---|---|
| Engine is under-revving. | 1 step downshift |
| Engine is over-revving. | 1 step upshift |
The ECM will restrict the changing of the shift range if it detects a malfunction in the CVT system.
If the vehicle speed and engine speed exceeds or goes below a preset level in response to the driver's downshift operation request, changing the shift range will be prohibited. In this case, the buzzer in the combination meter will sound to alert the driver.
Shift Lock System
A shift lock system consisting of a key interlock device* and a shift lock mechanism is used.
*: Models without entry and start system
On the models without the entry and start system, the key interlock device prevents the key from being pulled out after the ignition switch is turned off, unless the shift lever is moved to P. Thus, the driver is urged to park the vehicle with the shift lever in P.
The shift lock mechanism prevents the shift lever from being moved to a position other than P, unless the ignition switch is turned to ON, and brake pedal is depressed. It prevents the vehicle from starting off suddenly.
A shift lock release button, vehicle manually overrides the shift lock mechanism, is used.
CONSTRUCTION
Torque Converter Assembly
A compact and high-capacity torque converter is used.
A damper structure, which can perform lock-up operation starting in the low-speed range, is used. This absorbs engine torque fluctuations and provides excellent ride comfort.
A torque converter that is compatible with the flex lock-up control system has been adopted for the K312 type continuously variable transaxle. This improves the fuel economy further while allowing more fine controls.
| *1 | Pump Impeller | *2 | Turbine Runner |
| *3 | Lock-up Clutch | *4 | Stator |
| *5 | Damper | *6 | 1-way Clutch |
Oil Pump Assembly
A trochoid gear type oil pump is used.
The oil pump assembly has 1 inlet port and 2 outlet ports.
| *a | Conventional Models | *b | K312 |
| *c | Outlet Port | *d | Outlet Port 1 |
| *e | Outlet Port 2 | *f | Inlet Port |
When oil pressure exceeds a preset value, which is determined in accordance with the engine speed, the oil pump assembly discharges oil through 2 outlet ports, reducing the driving torque.
Forward/Reverse Switching Unit
The forward/reverse switching unit consists of a planetary gear, a forward clutch, and a reverse brake.
The forward clutch, which acts during a forward movement, connects the input shaft with the planetary carrier.
The reverse brake, which acts during reverse movement, keeps the ring gear stationary.
| *1 | Reverse Brake | *2 | Forward Clutch |
| *3 | Ring Gear | *4 | No. 1 Pinion Gear |
| *5 | Sun Gear | *6 | No. 2 Pinion Gear |
| *7 | Planetary Carrier | - | - |
| *a | Forward/Reverse Switching Unit | - | - |
Pulley and Steel Belt Unit
The widths of the grooves of the pulleys are changed through hydraulic control.
During acceleration, the action of shift solenoid valve SLP increases the oil pressure of the primary pulley, thus narrowing the width of the pulley groove.
During deceleration, the action of shift solenoid valve SLP decreases the oil pressure of the primary pulley, thus widening the width of the pulley groove.
The secondary pulley is hydraulically controlled by the shift solenoid valve SLS. It controls the belt clamping pressure to ensure the proper power transmission efficiency.
| *1 | Secondary Pulley | *2 | Steel Belt |
| *3 | Primary Pulley | - | - |
| *a | Pulley Ratio (Low) | *b | Pulley Ratio (High) |
| *c | Groove Width (Large) | *d | Groove Width (Small) |
The primary pulley uses a single piston construction.
| *a | Pulley Ratio (Low) | *b | Pulley Ratio (High) |
| *c | Chamber | - | - |
The steel belt consists of elements and 2 rows of steel rings. In contrast to chains and V-belts, which transmit power through the use of tensile force, the steel belt uses the compressive action (pushing force) of the elements to transmit power.
| *1 | Steel Ring | *2 | Element |
Reduction Gear and Differential
The reduction gear reduces the power output from the secondary pulley and transmits it to the differential.
A 2 pinion type differential is used.
| *1 | Reduction Drive Gear | *2 | Reduction Driven Gear |
| *3 | Front Differential | - | - |
Transmission Valve Body Assembly
The transmission valve body assembly consists of the upper and lower valve bodies and 5 shift solenoid valves.
| *1 | Upper Valve Body | *2 | Lower Valve Body |
| *3 | Shift Solenoid Valve SLP | *4 | Shift Solenoid Valve SC |
| *5 | Shift Solenoid Valve SLS | *6 | Shift Solenoid Valve SLU |
| *7 | Shift Solenoid Valve SL | - | - |
| *1 | Primary Pulley | *2 | Secondary Pulley |
| *3 | Lock-up Clutch | *4 | Brake |
| *5 | Clutch | *6 | Valve Body |
| *7 | Manual Valve | *8 | Speed Ratio Control |
| *9 | Belt Clamping Pressure Control | *10 | ON-OFF and Back Pressure Control |
| *11 | Clutch Pressure Control | *12 | Shift Solenoid Valve SLP |
| *13 | Shift Solenoid Valve SLS | *14 | Shift Solenoid Valve SLU |
| *15 | Shift Solenoid Valve SL | *16 | Shift Solenoid Valve SC |
| *17 | ECM | - | - |
To ensure the proper control of the belt clamping pressure necessary for transmitting torque, the system controls the hydraulic pressure applied to the secondary pulley. The transmission valve body assembly is provided with a dedicated hydraulic pressure circuit for belt clamping pressure control. This circuit optimally controls the hydraulic pressure applied to the secondary pulley, thus achieving superior torque transmission performance.
| *1 | Oil Pump Assembly | *2 | Primary Regulator Valve |
| *3 | Shift Solenoid Valve SLS | *4 | Shift Solenoid Valve SLP |
| *5 | No. 1 Line Pressure Modulator Valve | *6 | No. 2 Line Pressure Modulator Valve |
| *7 | Primary Pulley | *8 | Secondary Pulley |
Pulley ratio control is effected by controlling the hydraulic pressure applied to the primary pulley in order to provide fine-tuned control and a high level of reliability.
| *1 | Oil Pump Assembly | *2 | Primary Regulator Valve |
| *3 | Shift Solenoid Valve SLS | *4 | Shift Solenoid Valve SLP |
| *5 | No. 1 Line Pressure Modulator Valve | *6 | No. 2 Line Pressure Modulator Valve |
| *7 | Primary Pulley | *8 | Secondary Pulley |
Shift Solenoid Valves SC and SL
The functions of each solenoid valve are outlined in the table below.
| Shift Solenoid Valve | Type | Function |
|---|---|---|
| SC | 2-way | Used to switch control of the shift solenoid valve SLU between forward and reverse clutch control and lock-up clutch control. |
| SL | 2-way |
Shift Solenoid Valves SLS, SLP and SLU
The functions of each solenoid valve are outlined in the table below.
| Shift Solenoid Valve | Type | Function |
|---|---|---|
| SLS | Linear | Controls the oil pressure of the secondary pulley. |
| SLP | Linear | Controls the oil pressure of the primary pulley. |
| SLU | Linear | Performs forward and reverse clutch control or lock-up clutch control depending on the state of the shift solenoid valves SC and SL. |
Parking Lock Mechanism
A parking lock mechanism is used on the secondary pulley. The engagement of the parking lock pawl with the parking lock gear integrated with the secondary pulley locks the movement of the vehicle.
| *1 | Parking Lock Pawl | *2 | Parking Lock Gear |
Transmission Revolution Sensors and Oil Pressure Sensor
The transmission revolution sensor (NIN) detects the input shaft speed and assists in shift control.
The transmission revolution sensor (NOUT) detects the output shaft speed and assists in shift control.
The transmission revolution sensor (NT) detects the forward clutch turbine speed and assists in lock-up clutch pressure control and forward clutch pressure control.
The oil pressure sensor detects the hydraulic pressure applied to the secondary pulley and assists in belt clamping pressure control, which optimally controls the clamping pressure of the steel belt necessary for transmitting torque.
| *1 | Transmission Revolution Sensor (NIN) | *2 | Transmission Revolution Sensor (NOUT) |
| *3 | Oil Pressure Sensor | *4 | Transmission Revolution Sensor (NT) |
CVT Fluid Temperature Sensor
The CVT fluid temperature sensor detects the fluid temperature, effects shift control in accordance with the fluid temperature, and assists in lock-up clutch pressure control, forward clutch pressure control, and belt clamping pressure control.
| *1 | CVT Fluid Temperature Sensor | *2 | Transmission Valve Body Assembly |
Park/Neutral Position Switch Assembly
The park/neutral position switch assembly sends the P, R, N, D and M position signals to the ECM.
The ECM controls the CVT system in accordance with the shift lever position signals.
The ECM transmits signals to the combination meter assembly for the shift position indicator (P, R, N, D and M) in response to the signals received from the switches.
Transmission Oil Cooler
The transmission oil cooler uses engine coolant to warm up the CVT fluid quickly. Consequently, the friction losses of the CVT are quickly reduced, thus improving fuel economy.
After warming up the CVT fluid, the engine coolant flows into the transmission oil cooler to cool down the CVT fluid.
| *1 | Transmission Oil Cooler | - | - |
| *a | Engine Coolant Inlet | *b | Engine Coolant Outlet |
| *c | CVT Fluid Outlet | *d | CVT Fluid Inlet |
|
CVT Fluid Flow | |
Engine Coolant Flow |
Oil Pump with Motor Assembly
The exclusively used oil pump with motor assembly has been provided for the vehicles with the stop and start system and is installed on the front of the CVT case. This enables a stable CVT fluid supply at the time of idle stop, and delivers good responsiveness without any uncomfortable feel, and smooth drivability, at the time of vehicle start from the engine stopped status.
By integrating the oil pump motor driver into the oil pump with motor assembly, a small-sized and weight reduced system has been achieved.
The oil pump with motor assembly provided for the vehicles with the stop and start system is controlled by the engine stop and start ECU.
The configuration and operations of the parts other than the oil pump with motor assembly are the same as the vehicles without the stop and start system.
Tech Tips
The oil pump with motor assembly only operates when the engine is in the idle stop status. While the engine is operating, CVT fluid is supplied from the mechanical oil pump assembly.
| *1 | Oil Pump with Motor Assembly | - | - |
The oil pump with motor assembly consists of oil pump motor driver section, DC sensorless and brushless motor section, and oil pump section.
An internal gear type oil pump has been used for the oil pump section to provide a stable oil supply.
The oil pump motor driver controls the oil pump with motor assembly operations according to the signals (duty signals) from the engine stop and start ECU.
| *1 | Yoke | *2 | Pump Rotor |
| *3 | Shaft | *4 | Magnet Wire |
| *5 | Stator Core | *6 | Oil Pump Motor Driver |
| *7 | Magnet | - | - |
| *a | A - A Cross Section | *b | Oil Pump Section |
| *c | DC Sensorless and Brushless Motor Section | *d | Oil Pump Motor Driver Section |
Shift Control Mechanism
A gate type shift lever that uses a transmission control cable is used.
The shift control mechanism consists of a shift lock control unit assembly and a transmission control cable assembly.
| *1 | Transmission Control Cable Assembly | *2 | Shift Lock Control Unit Assembly |
| *a | Shift Pattern | - | - |
OPERATION
Forward/Reverse Switching Unit
The forward clutch is connected when advancing, and engine torque is input from the input shaft to the planetary carrier and is output to the primary pulley.
| *1 | Reverse Brake | *2 | Ring Gear |
| *3 | No. 2 Pinion Gear | *4 | Forward Clutch |
| *5 | No. 1 Pinion Gear | *6 | Sun Gear |
| *a | Input | *b | Output |
Engine torque is input to the sun gear when reversing. The ring gear is fixed by the reverse brake to transmit engine torque to the stepless shift transmission mechanism with inverse rotation.
| *1 | Reverse Brake | *2 | Ring Gear |
| *3 | No. 2 Pinion Gear | *4 | Forward Clutch |
| *5 | No. 1 Pinion Gear | *6 | Sun Gear |
| *a | Input | *b | Output |
CVT Power Flow
The changing of the pulley ratio is accomplished in a continuously variable manner by varying the widths of the grooves of the primary and secondary pulleys.
| *1 | Primary Pulley | *2 | Secondary Pulley |
| *3 | Reverse Brake | *4 | Forward Clutch |
| *5 | Input Shaft | *6 | Reduction Drive Gear |
| *7 | Reduction Driven Gear | *8 | Differential Ring Gear |
Shift Lever in D (Pulley Ratio Low)
| *1 | Primary Pulley | *2 | Secondary Pulley |
| *3 | Input Shaft | - | - |
| *a | Groove Width (Large) | *b | Groove Width (Small) |
| *c | Reverse Brake (Off) | *d | Forward Clutch (On) |
Shift Lever in D (Pulley Ratio High)
| *1 | Primary Pulley | *2 | Secondary Pulley |
| *3 | Input Shaft | - | - |
| *a | Groove Width (Small) | *b | Groove Width (Large) |
| *c | Reverse Brake (Off) | *d | Forward Clutch (On) |
Shift Lever in N
| *1 | Primary Pulley | *2 | Secondary Pulley |
| *3 | Input Shaft | - | - |
| *a | Groove Width (Large) | *b | Groove Width (Small) |
| *c | Reverse Brake (Off) | *d | Forward Clutch (Off) |
Shift Lever in R
| *1 | Primary Pulley | *2 | Secondary Pulley |
| *3 | Input Shaft | - | - |
| *a | Groove Width (Large) | *b | Groove Width (Small) |
| *c | Reverse Brake (On) | *d | Forward Clutch (Off) |
Oil Pump with Motor Assembly
Normal Operation
The oil pump assembly in the CVT, which is powered by the engine, generates oil pressure. At this time, the oil pressure to be applied to the oil pump with motor assembly is blocked by the check valve installed in the discharge section of the oil pump with motor assembly. The oil pump with motor assembly is not operating at this time.
Idle Stop Operation
During idle stop operation, the oil pump assembly operation is stopped. At this time, the oil pump with motor assembly operates according to the signals sent from the oil pump motor driver and generates oil pressure to open the check valve and supply oil pressure to the CVT valve body.
Engine Automatic Start Operation
During engine automatic start operation, oil pressure generated by both the oil pump with motor assembly and the oil pump assembly is applied to the system. When the oil pressure generated from the oil pump assembly exceeds the oil pressure generated from the oil pump with motor assembly, the check valve closes and the oil pressure generated from the oil pump with motor assembly is no longer applied. The oil pump with motor assembly stops according to signals such as engine speed.