HYBRID TRANSMISSION SYSTEM


  1. OUTLINE


    1. An L310 hybrid vehicle transmission is used. This hybrid vehicle transmission is composed of a power split mechanism, a multi stage shift device and a hydraulic pressure control mechanism, and it is combined with an 8GR-FXS engine to achieve superior drive force performance and fuel efficiency. Also, a multi-stage hybrid that combines the LEXUS Hybrid Drive with a multi stage shift device is used to achieve optimal driveability.

    2. The power split mechanism is composed of the Motor Generator No. 1 (MG1), which is mainly used as a generator, the Motor Generator No. 2 (MG2), which is mainly used as a drive source, and a front planetary gear, which splits the engine motive force between the rear wheel motive force and MG1.

    3. The multi stage shift device is composed of 2 planetary gears, 2 clutches, 2 brakes and 1 1-way clutch, and it shifts the power split mechanism output in 4 steps.

    4. The hydraulic pressure control mechanism is composed of a valve body with 5 linear solenoid valves and 2 3-way solenoid valves, engages the clutches and brakes and performs line pressure and shift-related hydraulic pressure control.

    5. Also, the power split mechanism and multi stage shift device are positioned in series to achieve improved fuel efficiency by efficiently transmitting drive force and improved acceleration performance by increasing the drive force in the low to medium speed area. This positioning also achieves reduced MG2 output and a small hybrid vehicle transmission.

    6. Cooperative control is performed between the power split mechanism and multi stage shift device to achieve a smooth shift feeling and superior driveability.

    7. A sequential shiftmatic system with paddle shift switch is used. Also, 10 speed automatic transmission simulated shift control is used to express a rhythmical engine sound, quick acceleration and crisp driving.

  2. SPECIFICATION


    1. Hybrid Vehicle Transmission Assembly

      Transmission Type L310
      Gear Ratio 1st 3.538
      2nd 1.888
      3rd 1.000
      4th 0.650
      Fluid Type Toyota Genuine ATF WS
      Fluid Capacity 6.8 Liters (7.2 US qts, 6.0 Imp. qts)
      Weight (Reference)* 140.2 kg (309.1 lb)

      Tech Tips

      *: Weight shows the figure with the fluid fully filled.

    2. Planetary Gear

      Power Split Mechanism Front Planetary Gear No. of Ring Gear Teeth 78
      No. of Pinion Gear Teeth 22
      No. of Sun Gear Teeth 34
      Multi Stage Shift Device Center Planetary Gear No. of Ring Gear Teeth 78
      No. of Pinion Gear Teeth 18
      No. of Sun Gear Teeth 42
      Rear Planetary Gear No. of Ring Gear Teeth 66
      No. of Pinion Gear Teeth 20
      No. of Sun Gear Teeth 26

    3. Friction Engagement Components

      No. 1 Clutch C1 6
      No. 2 Clutch C2 6
      No. 1 Brake B1 5
      No. 2 Brake B2 4

  3. MAIN FEATURES

    List of Development Items
    Item Fuel Efficiency Power Performance Silent Performance Shift Feeling Driveability Cooling Performance Compactness and Lightweight Maintenance Performance
    Gear Train ○ ○ ○ ○ ○
    Multi Stage Shift Device ○ ○ ○
    Cooling Mechanism (MG1 and MG2) ○ ○
    Hydraulic Pressure Control Mechanism ○
    Lubrication Control Valve ○
    Mechanical Oil Pump ○ ○
    Cooperative Control of Power Split Mechanism and Multi Stage Shift Device ○ ○
    10 Speed Automatic Transmission Simulated Shift Control ○ ○ ○
    Increased Engine Start Speed Range ○ ○
    Mount Support Structure ○
    Transmission Damper ○ ○
    ATF Filling Procedures ○
    MG1 and MG2 ○ ○ ○ ○ ○

    1. Multi-stage Hybrid


      1. The conventional hybrid system restricts the usage of the maximum engine output in certain speed areas, so the maximum engine output can only be used in the high speed area. The multi-stage hybrid combines the LEXUS Hybrid Drive and a multi stage shift device to expand the speed areas where the maximum engine output can be used, making it possible to use the maximum engine output in the medium speed area.

      2. The L310 hybrid vehicle transmission expands the usage area of the maximum engine output and uses 10 speed automatic transmission simulated shift control. The engine speed increases according to increases in the vehicle speed and the system selects the shift range according to driver acceleration requests, achieving a direct and forceful feeling of acceleration.

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        *1 Available vehicle speed area of engine maximum output (previous hybrid system)
        *2 Available vehicle speed area of engine maximum output (multi-stage hybrid)
        *3 Engine Speed (rpm)
        *4 Vehicle Speed (km/h)

    2. Power Split Mechanism and Multi Stage Shift Device Positioned in Series


      1. Compared to the L110 hybrid vehicle transmission, which uses a 2-step shift for only the MG2 motor rotation, the L310 hybrid vehicle transmission uses a 4-step shift for the output rotation of the power split mechanism. As a result, the drive force is increased to improve start-off performance and achieve improved fuel efficiency through the high-efficiency points.

        Figure 1. L310 Hybrid Vehicle Transmission

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        *1 Shifts Power Split Mechanism Output Rotation in 4 Steps
        *2 Engine
        *3 Power Split Mechanism
        *4 Multi Stage Shift Device

        Figure 2. L110 Hybrid Vehicle Transmission

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        *a 2-stage Motor Speed Reduction Planetary Gear
        *b Shifts MG2 Motor Speed in 2 Steps
        *c Engine
        *d Power Split Mechanism

      2. High theoretical transmission efficiency can be maintained to achieve superior fuel efficiency.

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