# In-Wheel Two-Speed AMT with Selectable One-Way Clutch for Electric Vehicles

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## Abstract

**:**

## 1. Introduction

## 2. Structure and Characteristics

#### 2.1. Planetary Gear Set

#### 2.2. Selectable One-Way Clutch

#### 2.3. Overall Structure and Characteristics

## 3. Gear Shifting Process

## 4. Simulation Model and Results

#### 4.1. Upshifting Process

#### 4.2. Downshifting Process

#### 4.3. Improvement of Jerk

## 5. Discussion

## 6. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 11.**Dynamic dual-parameter shifting schedule: (

**a**) Vehicle acceleration curves in different gears. (

**b**) Upshift and downshift curves.

**Figure 12.**Simulation results of the upshifting process: (

**a**) Changes of WMPC pressing force. (

**b**) Changes in torque transmitted by each component. (

**c**) Changes of struts rotation angle. (

**d**) Changes of ring gear angular deceleration. (

**e**) Changes in vehicle speed. (

**f**) Changes in jerk.

**Figure 13.**Simulation results of the downshifting process: (

**a**) Changes of WMPC pressing force. (

**b**) Changes in torque transmitted by each component. (

**c**) Changes of struts rotation angle. (

**d**) Changes of ring gear angular deceleration. (

**e**) Changes in vehicle speed. (

**f**) Changes in jerk.

**Figure 14.**Simulation results of the downshifting process after the improvement of the WMPC combined curve: (

**a**) Changes of WMPC pressing force. (

**b**) Changes in torque transmitted by each component. (

**c**) Changes of struts rotation angle. (

**d**) Changes of ring gear angular deceleration. (

**e**) Changes in vehicle speed. (

**f**) Changes in jerk.

Gear State | Motor Rotation Direction | SOWC Forward Struts State | SOWC Reverse Struts State | WMPC State |
---|---|---|---|---|

Neutral | - | Up | Up | Disengaged |

First gear | Forward | Down | Down | Disengaged |

Second gear | Forward | Up | Up | Engaged |

Reverse | Reverse | Down | Down | Disengaged |

Parameter | IW-AMT | NSK Ltd. Wheel Hub Motor [26] | Unit |
---|---|---|---|

Maximum output power | 35 | 25 | kW |

Maximum output torque | 620 | 850 | Nm |

Overall mass | 15.72 | 32 | kg |

Power density | 2.23 | 0.78 | kW/kg |

Torque density | 39.44 | 26.56 | Nm/kg |

Parameter | Value | Unit |
---|---|---|

Vehicle mass | 1036 | kg |

Tire radius | 0.2979 | m |

Vehicle frontal area | 1.4 | m${}^{2}$ |

Air resistance coefficient | 0.45 | - |

Rolling resistance coefficient | 0.011 | - |

Rotation mass correction coefficient | 1.04 | - |

Max motor torque | 21 | Nm |

Max motor speed | 20,000 | rpm |

Motor rotational inertia | 2.74 | kgcm${}^{2}$ |

First gear ratio | 29.51 | - |

Second gear ratio | 11.88 | - |

Equivalent vehicle rotational inertia | 107.74 | kgm${}^{2}$ |

Worm gear ratio | 35 | - |

Worm gear drive speed | 334 | rpm |

SOWC strut mass | 31.4 | g |

Compression spring stiffness coefficient | 2.81 | N/mm |

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**MDPI and ACS Style**

Meng, D.; Wang, F.; Wang, Y.; Gao, B.
In-Wheel Two-Speed AMT with Selectable One-Way Clutch for Electric Vehicles. *Actuators* **2021**, *10*, 220.
https://doi.org/10.3390/act10090220

**AMA Style**

Meng D, Wang F, Wang Y, Gao B.
In-Wheel Two-Speed AMT with Selectable One-Way Clutch for Electric Vehicles. *Actuators*. 2021; 10(9):220.
https://doi.org/10.3390/act10090220

**Chicago/Turabian Style**

Meng, Dele, Fei Wang, Yuhai Wang, and Bingzhao Gao.
2021. "In-Wheel Two-Speed AMT with Selectable One-Way Clutch for Electric Vehicles" *Actuators* 10, no. 9: 220.
https://doi.org/10.3390/act10090220