Hydrostatic Transmission Swashplate Control During Vehicle Deceleration

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Solution Overview

Problem

The efficiency of motive power transmission in hydrostatic stepless speed changing mechanisms is affected by increased hydraulic pressure during deceleration, leading to potential overheating and excessive load on the mechanism.

Innovation Solution

A control system that adjusts the swashplate angle based on detected hydraulic pressure and vehicle speed to maintain optimal operation, reducing load on the hydrostatic stepless speed changing mechanism and preventing excessive hydraulic pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the swashplate angle is not controlled during deceleration, then the vehicle can decelerate naturally, but the hydraulic pressure increases excessively and temperature rises

Engineering Contradiction:
Improvedeceleration capabilityVSAvoidhydraulic oil temperature
Core Design Contradiction:
SpeedVSTemperature

Solution Approach 1:

The controller dynamically adjusts the swashplate angle parameter based on detected hydraulic pressure and vehicle speed, changing the physical state of the hydrostatic transmission system to maintain optimal operating conditions during deceleration and prevent excessive temperature rise

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the swashplate angle is controlled to reduce hydraulic pressure, then temperature and efficiency are maintained, but the control system complexity increases

Engineering Contradiction:
Improvemotive power transmission efficiencyVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The controller implements a feedback mechanism by continuously detecting hydraulic pressure and vehicle speed, then adjusting the swashplate angle accordingly. This closed-loop control maintains reliable motive power transmission efficiency while managing system complexity through intelligent parameter adjustment based on real-time system state

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces complex mechanical control mechanisms with an electronic control system that uses sensors and a controller to adjust the swashplate angle, reducing mechanical complexity while maintaining or improving transmission efficiency and reliability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Stress or pressure

If the swashplate angle is adjusted frequently, then hydraulic pressure is controlled effectively, but the wear on the hydrostatic mechanism increases

Engineering Contradiction:
Improvehydraulic pressure controlVSAvoidmechanism durability
Core Design Contradiction:
Stress or pressureVSReliability

Solution Approach 1:

The system dynamically adjusts the swashplate angle based on real-time detection of hydraulic pressure and vehicle speed, allowing the hydrostatic mechanism to operate under optimal conditions that balance effective pressure control with reduced wear, thereby maintaining both pressure management and long-term durability

Inventive Principle:
Principle #15Dynamics

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

Maintains efficient motive power transmission by controlling the swashplate angle within an appropriate range, reducing the risk of overheating and excessive load, especially during deceleration.

Implementation Method 1

a hydrostatic stepless speed changing mechanism configured to subject motive power from the engine to speed changing and output the motive power

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP4015871B1Work vehicle
Publication Date: 2026.05.06 KUBOTA CORP
  • EP4015871B1 patent drawingFigure 1
  • EP4015871B1 patent drawingFigure 2
  • EP4015871B1 patent drawingFigure 3

AI summary

A work vehicle including: an engine (1); a speed changing apparatus (18) that includes a hydrostatic stepless speed changing mechanism (18A) and is configured to subject motive power transmitted from the engine (1) to speed changing and output the motive power; a travelling apparatus configured to travel on the motive power received from the speed changing apparatus (18); a speed detector (27) configured to detect a speed of the travelling apparatus (6, 7); a pressure detector (25, 26) configured to detect a hydraulic pressure in a closed circuit of the hydrostatic stepless speed changing mechanism (18A); and a controller (80) configured or programmed to: determine, by means of a determination module (81), whether or not a swashplate angle of the hydrostatic stepless speed changing mechanism (18A) is an angle suitable for stopping the work vehicle, based on the speed and the hydraulic pressure; and change the swashplate angle by means of an angle control module (82), based on a result of the determination by the determination module (81).