Dual Mode EPPV Transmission Power Split Configuration

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Solution Overview

Problem

Traditional hybrid drive systems, such as series hybrid designs, face inefficiencies due to overbuilding of electrical motors and generators to handle varying power loads, leading to increased cost, weight, and decreased efficiency, while single power source systems struggle to maintain optimal operation across different loads.

Innovation Solution

A dual mode input split compound split configuration EPPV transmission system that includes an internal combustion engine, two electric motors, and a multi-mode transmission with planetary gear sets and clutches, allowing for variable output speeds and efficient power sharing between the engine and electric motors, enabling both high and low speed ranges with synchronous mode changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If electrical motors and generators are overbuilt to handle varying power loads in series hybrid design, then the system can accommodate all potential loads, but the cost and weight increase and maximum efficiency decreases

Engineering Contradiction:

Improveability to handle varying power loadsVSAvoidweight of electrical motors and generators

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The patent divides the power delivery function into two separate power sources (engine and electric motor) that can operate independently or in combination. This segmentation allows each component to be sized appropriately for its specific function rather than requiring one oversized component to handle all scenarios

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between different power sources and operating modes based on real-time power demands. The control system adjusts the contribution of the engine and electric motor to match actual load requirements, preventing the need for oversized components

Inventive Principle:

Principle #15Dynamics

2Device complexity

If a single power source system is used, then the structure is simpler, but the engine must accelerate and decelerate between transmission ratios and cannot operate within its optimal operating band for extended periods

Engineering Contradiction:

Improvesimplicity of power source structureVSAvoidfuel efficiency of engine

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The engine serves multiple functions: it can directly drive the transmission for high-power demands and simultaneously drive the generator to produce electrical energy for storage or motor assistance. This multi-functionality allows the engine to operate in its optimal band while meeting varying power demands

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The engine can maintain continuous operation within its optimal operating band by driving the generator, which then supplies electrical energy during transient states when additional power is needed. This eliminates the need for the engine to frequently accelerate and decelerate

Inventive Principle:

Principle #20Continuity of useful action

3Adaptability or versatility

If the engine is sized to accommodate the largest power loads, then all potential loads can be handled, but the power source is greatly oversized for most loads leading to inefficient fuel use

Engineering Contradiction:

Improveability to handle largest power loadsVSAvoidfuel efficiency

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The system changes the operational parameters of the engine by keeping it sized for optimal efficiency rather than maximum power output. The electrical motor provides the additional power capability needed for peak loads, allowing the engine to operate at efficient parameters across most driving conditions

Inventive Principle:

Principle #35Parameter changes

4Adaptability or versatility

If extensive use of both power sources is required during transient states, then power demands are met, but the overall system efficiency decreases

Engineering Contradiction:

Improveresponse to transient power demandsVSAvoidsystem efficiency

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The system performs preliminary action by using the engine to generate and store electrical energy during steady-state operation. This stored energy is then available during transient states, reducing the need for simultaneous operation of both power sources and maintaining higher overall efficiency

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8075435B2Dual mode input split compound split configuration EPPV transmission

Publication Date: 2011.12.13 CATERPILLAR INC

AI summary

An improved dual mode EPPV transmission hybrid electric drive system uses a combination of power sources including an internal combustion engine, a first electric motor, and a second electric motor, and provides more efficient operation and compact installation. The improved dual mode EPPV transmission hybrid electric drive system includes a first planetary gear set including a first sun gear linked to a first ring gear via a pinion on a first carrier, and a second planetary gear set including a second sun gear linked to a second ring gear via a pinion on a second carrier, wherein the various elements of the planetary gear sets are configured to allow a dual mode synchronous shift operation. The system includes a first clutch and a second clutch, both of which may be dry clutches, for changing the mode of the transmission from a high mode to a low mode and vice versa.