Hydraulic Vehicle Engine Torque Control for Stall Prevention
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Solution Overview
Problem
Forklift trucks powered by engines with hydraulically-operated devices face engine stall risks in Eco-mode due to insufficient torque, especially when the engine is not warmed up and hydraulic oil is at high viscosity, leading to increased load and potential engine stall during loading operations.
Innovation Solution
A vehicle control unit and engine control unit system that monitors engine temperature and adjusts torque control based on coolant temperature, releasing torque control when the engine output is not stabilized and gradually increasing torque limit values as the engine warms up, preventing rapid torque changes and ensuring stable engine operation in Eco-mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Eco-mode is activated to improve fuel economy, then fuel efficiency is improved, but engine torque becomes insufficient leading to engine stall risk
Solution Approach 1:
The patent applies dynamics by making the torque control strategy adaptive rather than static. The control unit dynamically adjusts torque limitations based on real-time engine temperature conditions. When the engine is cold (below threshold temperature), the system disables torque limitation even in Eco-mode, allowing full torque output to prevent stalling. When the engine is warm (at or above threshold temperature), the system enables torque limitation to achieve fuel savings. This dynamic adaptation resolves the contradiction between fuel efficiency and engine stall prevention.
Solution Approach 2:
The patent changes the operational parameters of the engine control system based on temperature conditions. The key parameter change is the torque limit value, which is set to different levels depending on whether the engine temperature is below or above a predetermined threshold. This parameter change allows the system to optimize fuel efficiency when warm while preventing stalls when cold, effectively resolving the technical contradiction between these two opposing requirements.
2Use of energy by moving object
If torque control is applied in Eco-mode, then fuel consumption is reduced, but engine output becomes insufficient during loading operations
Solution Approach 1:
The system performs preliminary action by monitoring engine temperature and determining whether the engine is sufficiently warmed up before applying torque control. The control unit checks if the engine temperature has reached the predetermined threshold before enabling Eco-mode torque limitation. This preliminary check ensures that torque control is only applied when the engine has sufficient capacity to handle load variations, preventing power deficiency during loading operations while still achieving fuel savings when conditions are appropriate.
Solution Approach 2:
The patent implements feedback by continuously monitoring engine temperature and using this information to adjust torque control strategy. The control unit receives temperature feedback from the engine and dynamically adjusts the torque limitation setting based on whether the temperature is above or below the threshold. This feedback mechanism ensures that fuel consumption is optimized only when engine conditions permit, maintaining sufficient power output during loading operations.
3Use of energy by moving object
If engine is operated in Eco-mode with reduced torque, then fuel economy improves, but vehicle performance deteriorates under load
Solution Approach 1:
The system dynamically adjusts its operation mode based on real-time temperature feedback. When the engine is cold, the system operates in a high-performance mode that prioritizes vehicle productivity over fuel economy. When the engine is warm, the system transitions to Eco-mode with torque control to maximize fuel economy. This dynamic switching resolves the contradiction between fuel economy and vehicle performance by allowing both modes to operate in their optimal conditions.
Solution Approach 2:
The patent changes the operational parameters of the engine control system based on temperature conditions. The key parameter change is the torque limit value, which is set to different levels depending on whether the engine temperature is below or above a predetermined threshold. This parameter change allows the system to optimize fuel efficiency when warm while preventing stalls when cold, effectively resolving the technical contradiction between these two opposing requirements.
Data Source
Figure 1
Figure 2~3
AI summary
A vehicle (10) equipped with a hydraulically-operated device (15, 16) includes an engine (19) that drives the hydraulically-operated device (15, 16), a temperature detection unit (37) that detects a temperature of the engine (19), and a control unit (30, 31) that controls the engine (19). The control unit (30, 31) is allowed to control torque of the engine (19) in accordance with a predetermined specified torque limit value (R2) when the control unit (30, 31) is in an Eco-mode, and does not control the torque of the engine (19) in accordance with the specified torque limit value (R2) in the Eco-mode when the temperature detected by the temperature detection unit (37) is at a predetermined specified release temperature (T1) or lower. The release temperature (T1) is set as a temperature at which output of the engine (19) is hard to be stabilized.