Work Vehicle Traveling Speed Control System

Solution Overview

Problem

Conventional traveling speed control systems for work vehicles with hydrostatic transmissions struggle to ensure smooth starts and stable low-speed travel when heavily loaded, and they often lead to excessive engine wear and fuel wastage when not loaded, due to inappropriate throttle opening and output/input speed ratio management.

Innovation Solution

A traveling speed control system that prioritizes throttle opening increase over output/input speed ratio increase during idling for heavy loads, and reverses this prioritization for normal travel modes, using a travel mode selector and throttle setting device to manage engine speed and hydrostatic transmission ratios, ensuring stable starts and efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the throttle opening increases at a large rate during engine idling to ensure smooth start and stable low-speed travel under heavy load, then the vehicle starting performance is improved, but the engine rotates at excessively high speed causing shortened engine life and increased fuel consumption when not loaded

Engineering Contradiction:

Improvevehicle starting performanceVSAvoidfuel consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts the throttle opening increase rate based on the selected travel mode. In work travel mode, the throttle opening increases at a large rate to ensure smooth starting under heavy load. In normal travel mode, the throttle opening increases at a small rate to prevent excessive engine speed and reduce fuel consumption. This dynamic adjustment resolves the contradiction between reliable starting and fuel efficiency.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the parameter of throttle opening increase rate according to the travel mode selection. By switching between work travel mode and normal travel mode, the system optimizes the throttle opening behavior to match the actual load conditions, thereby resolving the contradiction between ensuring smooth start under heavy load and preventing excessive fuel consumption during normal operation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the throttle opening increases at a large rate during engine idling to ensure smooth start under heavy load, then the vehicle starting performance is improved, but the engine life is shortened due to excessively high-speed rotation when not loaded

Engineering Contradiction:

Improvevehicle starting performanceVSAvoidengine life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The system dynamically adjusts the throttle opening increase rate based on the selected travel mode. In work travel mode, the throttle opening increases at a large rate to ensure smooth starting under heavy load. In normal travel mode, the throttle opening increases at a small rate to prevent excessive engine speed and reduce fuel consumption. This dynamic adjustment resolves the contradiction between reliable starting and fuel efficiency.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the parameter of throttle opening increase rate according to the travel mode selection. By switching between work travel mode and normal travel mode, the system optimizes the throttle opening behavior to match the actual load conditions, thereby resolving the contradiction between ensuring smooth start under heavy load and preventing excessive fuel consumption during normal operation.

Inventive Principle:

Principle #35Parameter changes

3Speed

If the output/input speed ratio of HST is increased to increase traveling speed, then the vehicle speed is improved, but the engine power may be insufficient to start the vehicle when heavily loaded

Engineering Contradiction:

Improvevehicle speedVSAvoidengine power

Core Design Contradiction:

SpeedVSPower

Solution Approach 1:

The system performs preliminary action by prioritizing the increase of throttle opening before increasing the output/input speed ratio of HST during engine idling in work travel mode. This ensures that the engine generates sufficient power to start the vehicle under heavy load before the HST begins to increase speed ratio, thereby resolving the contradiction between achieving high vehicle speed and ensuring adequate engine power for starting under heavy load.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8758195B2Traveling speed control system for work vehicle

Publication Date: 2014.06.24 KANZAKI KOKYUKOKI MFG

AI summary

A traveling speed control system for a work vehicle comprises an engine having a variable throttle opening; a hydrostatic transmission driven by the engine, the hydrostatic transmission having a variable output/input speed ratio; a travel mode selecting manipulator for selecting either a work travel mode or a normal travel mode; and an acceleration manipulator for setting a traveling speed of the work vehicle. Increase of the throttle opening during idling, of the engine is prior to increase of the output/input speed ratio for increasing the traveling speed of the work vehicle when the work travel mode is selected, and the increase of the throttle opening prior to the increase of the output/input speed ratio is canceled when the normal travel mode is selected.