HST Work Vehicle Acceleration Control
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Solution Overview
Problem
Work vehicles equipped with HST traveling drive devices experience excessive acceleration and pitching when starting from a standstill or shifting from deceleration to acceleration, due to fluctuations in engine rotation speed, leading to delayed responsiveness and reduced work efficiency.
Innovation Solution
The implementation of an operation quantity detector, rotation speed detector, and prime mover control unit that calculates and adjusts the requested rotation speed based on acceleration and deceleration rates, preventing excessive acceleration and ensuring smooth transitions between deceleration and acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the increase rate of accelerator operation quantity is limited to prevent excessive acceleration, then vehicle pitching is reduced, but responsiveness when shifting from deceleration to acceleration is delayed
Solution Approach 1:
The patent applies dynamics by making the acceleration rate limit variable rather than fixed. The control unit dynamically adjusts the acceleration rate limit based on the vehicle's current operational state - using a first (stricter) limit during startup to prevent pitching, and a second (more permissive) limit during deceleration-to-acceleration transitions to improve responsiveness. This dynamic adjustment resolves the contradiction by adapting the stability control to the specific operational context.
Solution Approach 2:
The patent changes the parameter of acceleration rate limit based on operational conditions. By detecting whether the vehicle is in a startup state or a deceleration-to-acceleration state, the system changes the acceleration rate parameter accordingly - applying a stricter limit during startup and a more permissive limit during transitions from deceleration, thus resolving the contradiction between stability and responsiveness.
2Object-affected harmful factors
If the engine rotation speed is controlled to prevent excessive acceleration, then operator comfort is improved, but work efficiency is reduced
Solution Approach 1:
The system dynamically adjusts engine rotation speed control based on operational context. During startup, a stricter acceleration rate limit is applied to prevent excessive acceleration and improve operator comfort. During deceleration-to-acceleration transitions, a more permissive acceleration rate limit is applied to maintain work efficiency. This dynamic control strategy resolves the contradiction by adapting comfort and efficiency priorities to the specific operational phase.
Solution Approach 2:
The patent changes the engine rotation speed control parameters based on detected operational states. By switching between different acceleration rate limits (first limit for startup, second limit for deceleration-to-acceleration), the system optimizes the balance between preventing harmful excessive acceleration and maintaining productive work efficiency in different operational contexts.
Data Source
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AI summary
A work vehicle equipped with an HST traveling drive device, includes: an operation quantity detector that detects an operation quantity representing an extent to which an accelerator pedal is operated; a rotation rate detector that detects an actual rotation rate at a prime mover; a requested rotation rate calculation unit that calculates a requested rotation rate for the prime mover based upon the operation quantity detected by the operation quantity detector; and a prime mover control unit that controls the actual rotation rate based upon the requested rotation rate calculated by the requested rotation rate calculation unit. When the requested rotation rate is higher than a predetermined value, the requested rotation rate calculation unit calculates a rate of acceleration for the requested rotation rate based upon a difference between the requested and the actual rotation rate detected by the rotation rate detector and calculates the requested rotation rate based upon the calculated rate of acceleration.