Work Vehicle Transmission Controller Downhill Gear Stability

Solution Overview

Problem

Work vehicles with multistage transmissions experience frequent upshifts and downshifts while running downhill, leading to potential instability and reduced durability due to automatic gear changes.

Innovation Solution

A controller is implemented to inhibit transmission gear ratio changes for a predetermined time after a downshift, ensuring the vehicle maintains a stable gear stage while running downhill, unless conditions such as changes in accelerator position, braking, road inclination, or target speed commands necessitate a shift.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the transmission automatically changes transmission gears while running downhill, then the vehicle can maintain speed control, but the transmission gear ratio changes repeatedly causing instability and reduced durability

Engineering Contradiction:

Improvetransmission durabilityVSAvoidautomatic gear changing

Core Design Contradiction:

ReliabilityVSExtent of automation

Solution Approach 1:

The controller applies preliminary anti-action by detecting the downhill running state in advance and proactively inhibiting automatic transmission gear changes before repeated upshifts and downshifts can occur. This prevents the harmful automatic gear changing behavior while maintaining speed control through other means.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The controller performs preliminary action by identifying the downhill condition (accelerator opening below threshold, positive acceleration, speed exceeding maximum within predetermined time) and preemptively disabling automatic transmission shifting. This ensures the transmission remains in a stable gear stage before repeated gear changes can degrade durability.

Inventive Principle:

Principle #10Preliminary action

2Speed

If the transmission gear ratio is changed frequently to control speed downhill, then speed control is improved, but the frequency of upshift and downshift increases reducing stability

Engineering Contradiction:

Improvespeed controlVSAvoidgear stage stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The controller applies preliminary anti-action by detecting the downhill running state in advance and proactively inhibiting automatic transmission gear changes before repeated upshifts and downshifts can occur. This prevents the harmful automatic gear changing behavior while maintaining speed control through other means.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The controller dynamically adjusts transmission control based on running conditions. When downhill running is detected (accelerator opening below threshold, positive acceleration, speed exceeding maximum within predetermined time), automatic shifting is inhibited to maintain gear stage stability. When conditions change, normal automatic shifting resumes, allowing the system to adapt between stability and responsiveness.

Inventive Principle:

Principle #15Dynamics

3Stability of the object's composition

If the controller inhibits transmission gear ratio changes during downhill running, then gear stage stability is improved, but the ability to adapt to changing conditions may be reduced

Engineering Contradiction:

Improvegear stage stabilityVSAvoidresponse to condition changes

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The controller dynamically adjusts transmission control based on running conditions. When downhill running is detected (accelerator opening below threshold, positive acceleration, speed exceeding maximum within predetermined time), automatic shifting is inhibited to maintain gear stage stability. When conditions change, normal automatic shifting resumes, allowing the system to adapt between stability and responsiveness.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The controller continuously monitors running conditions (accelerator opening, acceleration, speed changes over time) and uses this feedback to determine when to inhibit or allow automatic transmission shifting. This feedback mechanism ensures the system maintains stability during downhill running while remaining adaptable when conditions change.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9574659B2Work vehicle and method of controlling the same

Publication Date: 2017.02.21 KOMATSU LTD

AI summary

A work vehicle including a transmission that transmits power of an engine to wheels at a plurality of different transmission gear ratios, the work vehicle traveling while maintaining a targeted speed by controlling a degree of opening of an accelerator, brakes, and the transmission, wherein the work vehicle includes a controller which inhibits change in the transmission gear ratio of the transmission when the transmission shifts up before lapse of a first predetermined time after the transmission shifts down while the vehicle is running downhill and then before a second predetermined time elapses, the transmission shifts down while the vehicle is running downhill.