Tilt Angle Control Device for Variable Displacement Pump Flow Accuracy
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Solution Overview
Problem
The control accuracy and responsiveness of the discharge amount of variable displacement pumps in tilting angle control devices are limited due to individual variability in the performance of electromagnetic proportional control valves, affecting the precise control of hydraulic actuators in construction machines like hydraulic excavators.
Innovation Solution
A tilting angle control device configuration that includes an operation unit, control unit, proportional control valve, and pressure detector, where the control unit calculates pressure control signals based on feedback signals and stored valve characteristics, allowing for precise adjustment of the tilting angle and discharge amount, and includes mechanisms to account for variability in proportional control valve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high flow rate variable displacement pump is provided to correspond to the hydraulic actuator having the highest allowable maximum flow rate, then the pump can supply sufficient flow rate to all actuators, but the discharge flow rate control accuracy deteriorates because the pump must be controlled to match each actuator's specific allowable maximum flow rate
Solution Approach 1:
The patent implements feedback control by detecting the actual discharge flow rate of the variable displacement pump and comparing it with the target flow rate. The control unit adjusts the tilting angle based on the flow rate detection result, creating a closed-loop control system that maintains accurate flow rate control even when the pump is sized for the highest flow rate requirement.
Solution Approach 2:
The patent changes the tilting angle parameter of the variable displacement pump to control the discharge flow rate. By adjusting the tilting angle dynamically based on feedback, the system can precisely control the flow rate to match each actuator's specific requirements despite the pump being capable of higher flow rates.
2Reliability
If the discharge flow rate is controlled to match each hydraulic actuator's specific requirements, then the actuators receive optimal flow rate, but the control system complexity increases
Solution Approach 1:
The patent uses feedback control where the actual discharge flow rate is detected and fed back to the control unit. This allows the system to automatically adjust the tilting angle to match each actuator's specific flow rate requirements without requiring complex manual control mechanisms.
Solution Approach 2:
The control system automatically adjusts the pump's discharge flow rate based on feedback detection, making the system self-regulating. The control unit independently manages the flow rate distribution to multiple actuators without requiring external intervention for each actuator's specific requirements.
3Productivity
If the variable displacement pump discharges maximum flow rate, then the hydraulic actuators can operate at maximum speed, but energy waste occurs when the flow rate exceeds the actuators' actual requirements
Solution Approach 1:
The patent implements dynamic control of the variable displacement pump's discharge flow rate by continuously adjusting the tilting angle based on actual actuator requirements. This dynamic adjustment allows the system to maintain high productivity when needed while minimizing energy waste during normal operation, replacing the static maximum flow rate approach.
Solution Approach 2:
The patent changes the discharge flow rate parameter dynamically by adjusting the tilting angle according to actual operational needs. This allows the system to operate at maximum speed when required while reducing flow rate to match actual demands, thereby minimizing hydraulic energy waste.
Data Source
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AI summary
A tilting angle control device 1 includes pressure sensors 51 to 56. Each of the pressure sensors 51 to 56 outputs to a control unit 60 a pressure command signal corresponding to an operation amount. The control unit 60 outputs to an electromagnetic proportional control valve 44 a pressure control signal corresponding to the pressure command signal, and the electromagnetic proportional control valve 44 outputs to a tilt adjustment mechanism 31 pilot pressure p2 corresponding to the pressure control signal. The tilt adjustment mechanism 31 adjusts a tilting angle α of a variable displacement pump 10L such that the tilting angle α becomes an angle corresponding to the pilot pressure p2. A pilot pressure sensor 45 detects the pilot pressure p2 to output a pressure feedback signal to the control unit 60. The control unit 60 calculates the pressure control signal based on the pressure feedback signal and the pressure command signal and performs feedback control of the pilot pressure p2.