Industrial Vehicle Engine Stall Prevention via Revving Control
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Solution Overview
Problem
Industrial vehicles, such as forklifts, experience engine stalls due to insufficient engine torque when handling increased loads, particularly when multiple hydraulic actuators are operated simultaneously, leading to instability and potential cargo handling disruptions.
Innovation Solution
The implementation of a controller system that performs revving control to increase engine speed and manages hydraulic oil supply by switching between supply and return oil passages, using threshold settings to prevent sudden engine speed drops and maintain stable operation during load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the discharge pipe opens when a decrease of the engine speed is detected, then the engine speed can be recovered, but the engine speed further decreases from when the discharge pipe opens to when the load on the hydraulic pump decreases, causing engine stall
Solution Approach 1:
The controller performs revving control that raises the engine speed in advance when detecting that an operation of the instruction member instructs a load operation to be performed, before the engine speed actually decreases. This preliminary action prevents the engine speed from dropping to stall conditions in the first place, eliminating the need for reactive discharge pipe opening and avoiding the harmful speed decrease that occurs with delayed response.
2Productivity
If multiple hydraulic actuators are operated at the same time, then cargo handling operations can be performed simultaneously, but the load on the hydraulic pump increases causing insufficient engine torque and engine stall
Solution Approach 1:
The controller detects when multiple hydraulic actuators are instructed to operate simultaneously and performs revving control to raise the engine speed in advance. This preliminary increase in engine speed ensures sufficient engine torque is available to handle the combined load of multiple actuators operating at the same time, maintaining both productivity and reliability.
Data Source
AI summary
An industrial vehicle includes an engine, a hydraulic pump, a cargo handling tool, a mast, a first hydraulic actuator, a second hydraulic actuator, an instruction member, a supply oil passage, and a controller. When the mast is being tilted forward, the controller performs revving control that raises the engine speed when detecting that an operation of the instruction member instructs a load operation that applies load to the engine.