Industrial Vehicle Speed Change Control System
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Solution Overview
Problem
Existing speed change systems for industrial vehicles, such as wheel loaders, often result in undesirable upshifts when approaching a truck with a low speed load, leading to increased vehicle speed and complex operations requiring the brake pedal, especially when loading earth and sand.
Innovation Solution
A speed change control system that includes a speed ratio detecting unit, a torque converter speed ratio-based speed changer, a vehicle speed detection unit, and a mode selection unit to control transmission shifts based on predetermined vehicle speeds and load conditions, preventing upshifts until a predetermined vehicle speed is reached, thereby maintaining a low speed stage for efficient loading operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmission shifts up automatically when the torque converter speed ratio is large, then the transmission can maintain optimal operating conditions, but the vehicle speed increases undesirably during low-speed loading operations
Solution Approach 1:
The patent applies dynamics by making the upshift determination conditional rather than fixed. The speed change control unit dynamically evaluates multiple parameters including torque converter speed ratio, vehicle speed, and accelerator operation amount to decide whether to permit upshift. This allows the system to adapt to different operating conditions - permitting upshift during normal operation while preventing it during low-speed loading, thus resolving the contradiction between maintaining optimal transmission conditions and preventing unwanted speed increases.
Solution Approach 2:
The patent changes the control parameters from solely torque converter speed ratio to a combination of parameters including vehicle speed and accelerator operation amount. By introducing additional parameters with threshold values, the system can distinguish between different operational contexts (normal driving vs. low-speed loading) and make informed upshift decisions, thereby preventing unwanted speed increases while maintaining transmission efficiency.
2Use of energy by moving object
If the transmission shifts up at high torque converter speed ratio, then fuel efficiency can be improved, but complex brake operations are required to maintain low speed during loading
Solution Approach 1:
The patent applies self-service by enabling the transmission control system to automatically manage speed stages based on detected operating conditions. The speed change control unit monitors vehicle speed, accelerator operation, and torque converter ratio, then autonomously determines whether to permit upshift without requiring driver intervention via brake operations. This eliminates complex manual operations while maintaining fuel efficiency through appropriate gear selection.
Solution Approach 2:
The system uses feedback by continuously monitoring vehicle speed and accelerator operation amount alongside torque converter speed ratio. This multi-parameter feedback mechanism allows the control unit to accurately determine the operational context and make intelligent upshift decisions, improving fuel efficiency during normal operation while preventing unwanted upshifts during loading operations without requiring complex brake interventions.
3Productivity
If the transmission maintains low speed stage during loading operations, then loading efficiency is improved, but the torque converter speed ratio may become excessively large
Solution Approach 1:
The patent applies dynamics by implementing conditional upshift control that adapts to loading operations. During low-speed loading, the system detects the operational context through vehicle speed and accelerator operation monitoring, then dynamically adjusts upshift permission to maintain the low speed stage necessary for loading efficiency. This dynamic control prevents excessive torque converter speed ratios while preserving the low-speed operation needed for effective loading.
Data Source
AI summary
A speed change control system for an industrial vehicle includes: a speed ratio detecting unit that detects a speed ratio of speeds of an input shaft and of an output shaft of a torque converter; a torque converter speed ratio-based speed changer that shifts up or shifts down a speed stage of a transmission 3 in response to the detected speed ratio; a vehicle speed detection unit that detects a speed of the vehicle; a mode selection unit that selects any one of an L-mode and an H-mode; and a speed change control unit that permits an upshift provided that the vehicle speed is equal to or higher than a first predetermined value when the L-mode is selected whereas permits the upshift provided that the vehicle speed is higher than another predetermined value which is larger that the predetermined value when the H-mode is selected.