Construction Machine Engine Speed Control Using Feedforward Feedback
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Solution Overview
Problem
Existing construction machines face issues with maintaining engine rotational speed at a target due to variable load torque, leading to suboptimal operability and reduced fuel efficiency.
Innovation Solution
A control device that includes a rotational speed detection unit and a control unit capable of executing feedforward and feedback control to dynamically adjust the engine's target rotational speed based on load torque changes, using a variable displacement hydraulic pump and actuator system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If feedforward control with fixed correction amount is used, then the control structure is simple, but the engine rotational speed cannot be statically determined to the target rotational speed even when load torque is statically determined, causing fuel efficiency to deteriorate
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed correction amount to a dynamic correction amount that varies based on the temporal change rate of load torque. The control unit calculates the temporal change rate of load torque and determines the correction amount accordingly, allowing the system to adapt to different operating conditions and achieve static rotational speed determination when load torque is stable, thereby improving fuel efficiency.
Solution Approach 2:
The patent changes the parameter of correction amount from a fixed value to a variable value that depends on the temporal change rate of load torque. By introducing this parameter change, the system can optimize fuel injection amounts dynamically, ensuring that the engine rotational speed is statically determined to the target rotational speed when load torque is stable, thus resolving the fuel efficiency issue.
2Speed
If the correction amount is added to target rotational speed regardless of load torque speed, then the control response is immediate, but the engine rotational speed fluctuates and fuel efficiency deteriorates when load torque changes
Solution Approach 1:
The patent changes the correction amount parameter based on the temporal change rate of load torque. When load torque changes rapidly, a larger correction amount is applied to maintain responsive control. When load torque is stable, a smaller or zero correction amount is used, allowing the engine rotational speed to be statically determined and improving fuel efficiency. This dynamic parameter adjustment resolves the contradiction between response speed and fuel efficiency.
3Adaptability or versatility
If the engine rotational speed is not statically determined to the target rotational speed, then the system can respond to load changes, but the engine operates at suboptimal speeds reducing fuel efficiency
Solution Approach 1:
The patent applies dynamics by making the correction amount dependent on the temporal change rate of load torque. This allows the system to maintain adaptability to load changes while achieving static rotational speed determination when load torque is stable. The dynamic adjustment of correction amount based on load torque's temporal change enables the engine to operate at optimal speeds, improving fuel efficiency without sacrificing responsiveness.
Data Source
AI summary
A control device includes a rotational speed detection unit and a control unit. The control unit executes each of: feedforward control of calculating a load torque speed of an engine based on a discharge amount commanded for a hydraulic pump, and correcting a target rotational speed in accordance with at least the load torque speed; and feedback control of correcting the target rotational speed in accordance with a deviation between the target rotational speed of the engine and a rotational speed detected by the rotational speed detection unit.