Variable Pump Capacity Control for Smooth Hydraulic Actuation
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Solution Overview
Problem
Existing hydraulic driving systems fail to appropriately adjust the flow rate of oil supplied to an actuator based on the rotational speed of the pump, leading to potential shocks, cavitation, and inefficient operation due to sudden changes in flow rate.
Innovation Solution
A hydraulic driving system that includes a controller to regulate the pump capacity based on the rotational speed, setting an upper limit for the pump capacity change amount to prevent sudden changes in flow rate, thereby ensuring a smooth and efficient operation of the actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pump capacity is increased to improve the flow rate of oil supplied to the actuator, then the acceleration of the actuator is improved, but shocks occur during activation
Solution Approach 1:
The controller performs preliminary action by gradually increasing the pump capacity from a lower level before reaching the target capacity, rather than immediately setting it to the target value. This gradual increase approach prevents sudden flow rate changes that cause shocks during actuator activation, while still achieving the required acceleration performance.
2Loss of time
If the pump capacity is suddenly increased to improve the response speed of the actuator, then the responsiveness is improved, but cavitation and equipment damage may occur
Solution Approach 1:
The system applies dynamics by making the pump capacity change amount dynamic rather than fixed. The controller adjusts the capacity change amount based on the current pump rotational speed, allowing larger changes at higher speeds and smaller changes at lower speeds. This dynamic adjustment maintains responsiveness while preventing cavitation and equipment damage across varying operating conditions.
3Object-affected harmful factors
If a fixed upper limit value is used for the pump capacity change amount, then the shock reduction effect is improved, but the acceleration effect depending on pump rotational speed is lost
Solution Approach 1:
The invention applies parameter changes by making the upper limit value of the pump capacity change amount variable based on the pump rotational speed. Instead of using a fixed limit, the controller adjusts the limit parameter according to the current rotational speed, enabling shock reduction at all speeds while maintaining the ability to provide acceleration effects appropriate to each operating condition.
Data Source
AI summary
A hydraulic driving system includes a pump, an actuator, and a controller. The pump is rotationally driven by a power source to discharge oil. The pump has a capacity which is changeable. The actuator is activated by a supply of the oil discharged from the pump. The controller controls the capacity of the pump in accordance with a manipulation content for the actuator. The controller changes, on the basis of a rotational speed of the pump, an upper limit value of a magnitude of a pump capacity change amount being a change amount of the capacity of the pump per unit time.