Work Vehicle Transmission Control for Efficient Braking

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Solution Overview

Problem

Conventional work vehicles face challenges in increasing the output of hydromechanical transmissions without sacrificing power transmission efficiency, leading to increased manufacturing costs and weight, and require complex control systems for coordinating transmission and brake operations, resulting in operator discomfort and reduced operability.

Innovation Solution

A work vehicle design that incorporates a control system to coordinate the outputs of straight-traveling and turning transmission paths, using a brake mechanism and control section to manage driving force and deceleration based on brake operation tool input, ensuring safe stopping and smooth deceleration while preventing unintended turns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the capacity of the hydromechanical transmission is increased to increase output, then the output is improved, but manufacturing costs increase and power transmission efficiency deteriorates

Engineering Contradiction:

Improveoutput of hydromechanical transmissionVSAvoidpower transmission efficiency

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The transmission system is divided into two independent paths: a straight-traveling system using a first stepless transmission device and a turning system using a second stepless transmission device. Each path handles specific operational requirements separately, allowing the straight-traveling path to operate independently for efficiency while the turning path handles directional changes, thus preventing efficiency loss during turning operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A control section acts as an intermediary between the operator's input and the transmission systems. It coordinates the outputs of both stepless transmission devices, managing the combination of driving forces and controlling brake operations to prevent conflicts between driving and braking forces, thereby maintaining power transmission efficiency while enabling complex maneuvers.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Power

If the capacity of the hydromechanical transmission is increased to increase output, then the output is improved, but the size and weight of the transmission increase

Engineering Contradiction:

Improveoutput of transmissionVSAvoidweight of transmission

Core Design Contradiction:

PowerVSWeight of moving object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The brake mechanism serves multiple functions: it brakes the traveling units during normal operation, prevents unintended turns by controlling the turning system, and works in coordination with the control section to manage both straight-traveling and turning operations. This multi-functionality reduces the need for additional specialized components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If complex control systems are used to coordinate transmission and brake operations, then stopping safety is improved, but operator comfort deteriorates

Engineering Contradiction:

Improvestopping safetyVSAvoidoperator comfort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The control section automatically manages the coordination between the two stepless transmission devices and the brake mechanism based on operational inputs. The system self-regulates the combination of driving forces and brake application, eliminating the need for the operator to manually coordinate multiple controls, thus maintaining safety while simplifying operation.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The control section continuously monitors and coordinates the outputs of both transmission devices and adjusts brake application accordingly. This feedback mechanism ensures that braking forces are applied smoothly and in coordination with driving forces, preventing conflicts and providing predictable, comfortable stopping behavior while maintaining high safety standards.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10576944B2Work vehicle

Publication Date: 2020.03.03 YANMAR POWER TECH CO LTD

AI summary

A work vehicle equipped with: a straight-traveling system transmission path including a first stepless transmission device, a turning system transmission path including a second stepless transmission device, left and right traveling units that receive a driving force from an engine and move the work vehicle in forward and in reverse, and a brake operation tool that actuates a brake mechanism. The output of the straight-traveling system transmission path and the output of the turning system transmission path are combined to drive the traveling units. When the operation amount to the brake operation tool exceeds a first predetermined amount, a control section blocks the driving force output from the first stepless transmission device, and at the same time, sets a swash plate of the second stepless transmission device in a neutral state.