Hydraulic Drain Valve Control for Cold-Start Work Machines
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Solution Overview
Problem
Starting an engine in work machines is difficult due to the high viscosity of hydraulic fluid, especially in cold climates, as the hydraulic pump is heavily loaded, making it hard to initiate engine rotation.
Innovation Solution
Incorporating a drain path in the hydraulic circuit with an on-off valve controlled by a controller to discharge pressurized fluid before engine start, reducing the load on the hydraulic pump and facilitating engine rotation, and closing the valve once the engine is started to maintain pressure for the work apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the hydraulic pump is driven by the engine to supply pressurized fluid to the work apparatus, then the work apparatus can operate with sufficient pressure, but the engine becomes heavily loaded by the hydraulic pump especially when the hydraulic fluid has high viscosity in cold climates, making it hard to start the engine
Solution Approach 1:
The on-off valve is opened in advance before engine start to drain hydraulic fluid from the hydraulic circuit through the drain path. This preliminary action reduces the viscosity and load of the hydraulic fluid on the hydraulic pump before the engine attempts to start, thereby improving engine startability while preventing loss of pressurized fluid during operation
2Ease of operation
If the hydraulic circuit is opened to drain pressurized fluid before engine start, then the load on the hydraulic pump is reduced facilitating engine rotation, but the pressurized fluid may be lost through drainage
Solution Approach 1:
The on-off valve dynamically switches between open and closed states based on engine operation phase. It is opened during engine start to allow drainage and reduce load, then automatically closed after engine start to prevent loss of pressurized fluid. This dynamic control resolves the contradiction between needing drainage for easy starting and preventing fluid loss for operational pressure
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
This configuration allows for easier engine starting by reducing the load on the hydraulic pump and ensuring stable pressurized fluid supply to the work apparatus, enhancing engine startability and operational efficiency.
Implementation Method 1
a drain path connected to a second portion of the hydraulic circuit upstream of the first portion to discharge the pressurized fluid from the hydraulic circuit not through the relief valve
Implementation Method 2
a relief valve connected to a first portion of the hydraulic circuit upstream of the control valve to set a pressure of the pressurized fluid to be supplied to the work apparatus driver
Implementation Method 3
a hydraulic pump drivable by the engine, a work apparatus driver to receive a pressurized fluid
Data Source
AI summary
A work machine includes an engine, a hydraulic pump, a work apparatus driver to receive a pressurized fluid, a hydraulic circuit connecting the hydraulic pump with the work apparatus driver, a control valve in the hydraulic circuit, a relief valve connected to a first portion upstream of the control valve, a drain path connected to a second portion upstream of the first portion, an on-off valve to open and close the drain path, and a controller to control the on-off valve based on a state of the engine. The controller is configured or programmed to keep the on-off valve open after detecting an operation to start the engine until detecting a start of the engine and to close the on-off valve in response to detecting the start of the engine.