Hybrid Power-Split Drivetrain With Torque Converter for Low-Speed Drive Torque

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Solution Overview

Problem

Existing hybrid vehicles with power split mechanisms face limitations in transmitting maximum drive torque to the drive wheels due to insufficient reaction torque from the motor, especially at low vehicle speeds.

Innovation Solution

The vehicle incorporates a torque converter between the input member and the output member, along with a reaction mechanism and a differential mechanism, to establish a reaction torque and multiply the torque transmitted to the drive wheels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the engine speed is increased to increase the output torque of the engine, then the output torque of the engine is improved, but the rotational speed of the motor is increased causing the reaction torque to decrease

Engineering Contradiction:

Improveoutput torque of the engineVSAvoidreaction torque of the motor

Core Design Contradiction:

ForceVSForce

Solution Approach 1:

A torque converter is introduced as an intermediary component between the engine and the power split mechanism. The torque converter multiplies the engine torque before it reaches the power split mechanism, allowing the engine to operate at higher speeds for maximum torque output while the torque converter compensates for the reduced reaction torque from the motor through hydraulic torque multiplication.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the operational parameters by allowing the engine to operate at higher rotational speeds beyond the traditional limits imposed by motor reaction torque constraints. The torque converter enables the engine to reach its maximum torque region by providing hydraulic multiplication, fundamentally changing the operating point parameters of the engine.

Inventive Principle:

Principle #35Parameter changes

2Power

If the rotational speed of the motor is increased to match the increased engine speed, then the engine torque transmission is improved, but the output torque of the motor decreases

Engineering Contradiction:

Improveengine torque transmissionVSAvoidoutput torque of the motor

Core Design Contradiction:

PowerVSPower

Solution Approach 1:

The torque converter acts as a mediator that decouples the direct relationship between engine speed and motor speed. It allows the engine to rotate at high speeds while the torque converter multiplies the torque, so that the power split mechanism receives sufficient torque even when the motor operates at speeds where its output torque is reduced.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Force

If the maximum torque of the engine is transmitted to the drive wheels, then the propulsion capability is improved, but the reaction torque from the motor becomes insufficient

Engineering Contradiction:

Improvedrive torque to drive wheelsVSAvoidreaction torque from motor

Core Design Contradiction:

ForceVSForce

Solution Approach 1:

The torque converter serves as a torque multiplication intermediary that enables the transmission of maximum engine torque to the drive wheels. By placing the torque converter between the engine and the power split mechanism, the system can deliver the full engine torque capability to the wheels while the torque converter compensates for the insufficient reaction torque from the motor through hydraulic multiplication.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration allows for increased maximum drive torque transmission from the internal combustion engine to the drive wheels without excess or deficiency, enhancing the vehicle's propulsion capabilities at low speeds.

Implementation Method 1

a torque converter is arranged between the input member and the output member to deliver the torque from the input member to the output member while multiplying the torque

Methodology Applied

Scientific EffectTorque multiplication: Hydraulic Press

Implementation Method 2

a one-way clutch that is interposed between the input member and the pump impeller to interrupt torque transmission between the input member and the pump impeller while the pump impeller is rotated at a speed higher than a rotational speed of the input member

Methodology Applied

Scientific EffectOne-way clutch mechanism: Ratchet

Data Source

PatentUS12330502B2Vehicle

Publication Date: 2025.06.17 TOYOTA JIDOSHA KK

AI summary

A vehicle designed to increase a maximum drive torque transmitted from an engine to drive wheels. The vehicle comprises: an input member to which a torque is delivered from the engine; an output member connected to drive wheels; a reaction mechanism that establishes a reaction torque; and a differential mechanism. A differential mechanism comprises: an input element connected to the input member; an output element connected to the output member; and a reaction element connected to the reaction mechanism. A torque converter is arranged between the input member and the output member.