Engine Hydraulic Control Device for Piston Cooling
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Solution Overview
Problem
Existing hydraulic control devices for engines face challenges in lubrication oil distribution during warm-up, where high viscosity oil at low temperatures leads to excessive hydraulic pressure, causing premature piston cooling and potential lubrication shortages when relief pressure is reduced.
Innovation Solution
A hydraulic control device with an oil jet and switching valve system that selectively supplies oil to the piston or returns it to the pump based on engine operating conditions, preventing excessive piston cooling during warm-up and ensuring stable lubrication pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the pressure at which oil injection to the piston head is started is set to a hydraulic pressure after the engine is warmed up, then the piston cooling function is maintained at high temperature, but oil is injected to the piston during warm-up causing premature cooling and preventing early warm-up
Solution Approach 1:
The patent applies dynamics by making the oil injection control pressure variable rather than fixed. The control pressure is set differently based on engine operating conditions: a first control pressure during warm-up (when hydraulic pressure is low) and a second control pressure during normal operation (when hydraulic pressure is high). This dynamic adjustment allows the system to adapt to changing temperature conditions and achieve early warm-up while maintaining piston cooling when needed.
2Object-generated harmful factors
If the relief pressure of oil in the relief valve is reduced during engine warm-up, then the pressure in the oil passage is set equal to lower than the pressure at which oil injection to the piston head is started, suppressing oil injection and piston cooling, but oil supply to parts in the engine is insufficient and lubrication may be inadequate
Solution Approach 1:
The patent segments the oil passage into multiple independent paths: a first oil passage for supplying oil to the piston head, a second oil passage for supplying oil to lubrication parts, and a third oil passage for returning oil to the sump. This segmentation allows independent control of oil flow to different components. During warm-up, the first passage can be controlled to limit piston cooling while the second passage ensures adequate lubrication supply, resolving the contradiction between suppressing excessive cooling and maintaining lubrication sufficiency.
Solution Approach 2:
The patent introduces a control pressure (intermediary parameter) that mediates between the relief pressure and the injection pressure. By setting the control pressure to a first control pressure during warm-up and a second control pressure during normal operation, the system can independently regulate oil injection to the piston head without affecting the relief pressure or lubrication supply, thus resolving the contradiction.
3Object-generated harmful factors
If an injection valve of injecting oil to the piston head is forcibly stopped, then oil injection is suppressed during warm-up, but the pressure in the oil passage increases and the load on the oil pump increases
Solution Approach 1:
The patent extracts the oil flow control function from the injection valve and relocates it to a control pressure mechanism. Instead of forcibly stopping the injection valve (which would cause pressure buildup and increased pump load), the system controls the control pressure to regulate oil flow naturally. This extraction of the control function allows suppression of piston cooling during warm-up while avoiding excessive pressure increases and pump load.
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 effectively suppresses piston cooling during engine warm-up, expediting temperature rise and maintaining stable lubrication pressure, thereby improving engine warm-up efficiency and preventing lubrication shortages.
Implementation Method 1
a hydraulic control device that supplies oil for lubrication to internal parts of an engine that require lubrication. Such a hydraulic control device is equipped with an oil pump that pressurizes oil for distribution
Implementation Method 2
a relief valve that adjusts oil sending pressure
Implementation Method 3
the hydraulic control device injects oil for lubrication to a piston head in order to cool a piston
Data Source
AI summary
A hydraulic control device is equipped with an oil jet that injects oil to a piston, an oil gallery through which oil injected by the oil jet and oil supplied to a lubrication part of an engine pass, an oil pump that pumps oil to the oil gallery, and a switching valve that is provided on an oil jet passage connecting the oil gallery and the oil jet together and leads oil supplied from the oil gallery to either the oil jet or an oil pan disposed at an upstream side of the oil pump. An ECU controls the switching valve on the basis of an engine speed and an engine cooling water temperature.