Hydraulic Warm-Up Circuit for Cold-Start Response Lag
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Solution Overview
Problem
Hydraulic systems for working machines experience response lag and unstable warming in cold temperatures due to high viscosity of hydraulic fluid and inadequate warming of the PLS signal tube and throttle, leading to frequent valve switching and operator discomfort.
Innovation Solution
Incorporation of a warm-up circuit with a switch valve and check valve to supply hydraulic pilot fluid to the signal tube, preventing backward flow and controlling the switch valve based on temperature and engine speed to maintain stable warming of the hydraulic system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hydraulic fluid is used in cold temperatures, then the hydraulic system can operate, but the high viscosity of the cold hydraulic fluid causes response lag and unstable warming
Solution Approach 1:
The warm-up circuit is activated before normal operation to pre-warm the hydraulic fluid in the PLS signal tube and throttle. This preliminary action prevents the high viscosity and response lag that would occur if the system started with cold fluid, ensuring smooth transition to normal operation without frequent valve switching.
2Ease of operation
If the PLS signal tube and throttle are not adequately warmed, then the hydraulic system structure remains simple, but response lag occurs and frequent valve switching is required
Solution Approach 1:
A dedicated warm-up circuit is introduced as an intermediary system between the main hydraulic pump and the PLS signal tube. This circuit includes a warm-up pump, control valve, and associated components that specifically target the warming of the signal tube and throttle without requiring major modifications to the existing hydraulic system architecture.
3Adaptability or versatility
If the switch valve is frequently switched to control warming, then the hydraulic system can adapt to temperature changes, but operator discomfort increases and system reliability decreases
Solution Approach 1:
The control valve in the warm-up circuit is actuated based on feedback from temperature sensors that monitor the hydraulic fluid temperature in the PLS signal tube. When the temperature falls below a predetermined threshold, the control valve activates the warm-up pump to circulate warm fluid through the signal tube and throttle. This feedback mechanism eliminates the need for frequent manual valve switching by automatically maintaining the required temperature conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution eliminates response lag by warming the signal tube and throttle, reduces the need for frequent valve switching, and maintains stable warming of the hydraulic system, improving operational efficiency and reducing operator discomfort.
Implementation Method 1
the temperature of the hydraulic operation fluid becomes low, and thus the cold, low-temperature, hydraulic operation fluid has a high viscosity resistance
Implementation Method 2
a warm-up circuit configured to supply the hydraulic pilot fluid to a downstream side of the throttle provided on the signal tube
Data Source
AI summary
A hydraulic system includes: hydraulic actuators; a control valve for controlling the hydraulic actuators; a tank for storing a hydraulic operation fluid; a variable displacement pump for supplying the hydraulic operation fluid to the hydraulic actuators; a regulator for controlling the variable displacement pump; a pilot pump for discharging a hydraulic pilot fluid; a load sensing system for maintaining a differential pressure to be a constant pressure, the differential pressure being obtained by subtracting a second signal pressure from a first signal pressure that is the discharge pressure of the variable displacement pump, the second signal pressure being the maximum one of the load pressures generated in the hydraulic actuators; a signal tube for sending the second signal pressure to the regulator; a throttle provided on the signal tube; and a warm-up circuit for supplying the hydraulic pilot fluid to a downstream side of the throttle.