Injector Valve Testing Method for Two-Stroke Engines
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Solution Overview
Problem
Current methods for testing injector valves for leaks in two-stroke combustion engines do not effectively assess the tightness of both the suction and nozzle valves, which is crucial for safety and performance.
Innovation Solution
A method involving the supply of control oil and test gas to the injector valve at specific pressures to check for leaks, where the presence of test gas bubbles in a liquid container indicates valve leakage, allowing for the assessment of both suction and nozzle valve tightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control oil pressure is increased to open the nozzle valve for testing, then the opening pressure of the nozzle valve can be checked, but the suction valve leakage cannot be detected
Solution Approach 1:
The test is divided into two separate segments: first testing the nozzle valve opening pressure by increasing control oil pressure, then testing the suction valve tightness by introducing test gas at lower pressure while maintaining control oil pressure. This segmentation allows each valve to be tested under its specific operating conditions without interference from the other test.
Solution Approach 2:
A test gas (such as nitrogen or carbon dioxide) is introduced as an intermediary substance to detect suction valve leakage. The test gas is supplied to the plunger piston chamber at a pressure lower than the suction valve opening pressure, and any leakage is detected by observing bubbles in a liquid container connected to the nozzle openings, providing a safe and visible indication of valve tightness.
2Reliability
If test gas pressure is increased above suction valve opening pressure to detect leaks, then leakage can be detected, but the suction valve will open and cause false positive results
Solution Approach 1:
The test gas pressure is carefully controlled to be below the suction valve opening pressure threshold. By changing the pressure parameter to remain sub-threshold, the suction valve remains closed during the test, allowing accurate detection of leakage through the closed valve without false positives from valve opening.
Solution Approach 2:
The test uses partial action by supplying test gas at a pressure that is sufficient to detect leakage (above atmospheric pressure) but excessive pressure is avoided to prevent valve opening. This controlled partial pressure application enables leakage detection while maintaining valve closure.
3Reliability
If both valves are tested simultaneously under high pressure, then comprehensive testing is achieved, but safety risks and test complexity increase
Solution Approach 1:
The testing is performed in periodic sequence rather than simultaneously: first the nozzle valve opening pressure is tested by increasing control oil pressure, then the suction valve tightness is tested by introducing test gas. This periodic action ensures comprehensive testing while maintaining simple, manageable test procedures with clear step-by-step progression.
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 method provides a comprehensive leak test for injector valves, ensuring the safety and performance of two-stroke combustion engines by accurately determining the tightness of both suction and nozzle valves.
Implementation Method 1
any test gas reaching through the nozzle openings into the flexible hose is observed as bubbles in the liquid of the container
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A method of testing a valve body (22) of an injector valve (10) for liquid gas is provided. The method comprises supplying control oil to a nozzle piston (41) via a control oil channel (30) at a first control oil pressure, which first control oil pressure is higher than or equal to a predetermined control oil opening pressure for which the nozzle valve (38) is configured to open, supplying a test gas to the suction piston (35) via a plunger piston chamber (23) at a first test gas pressure being lower than a predetermined test gas opening pressure for which a suction valve (32) is configured to open, and checking whether any of the supplied test gas is reaching out through the nozzle openings (46). If no test gas reaches out through the nozzle openings (46), the suction valve (32) is tight. A method for testing an injector valve (10) holding the valve body (22) is also provided, the method comprising supplying sealing oil at a predetermined sufficient sealing pressure to a plunger piston chamber (23) and a nozzle valve chamber (39) via a sealing oil channel (31), supplying hydraulic oil at a first fuel inlet pressure being high enough to open a plunger valve (18), to the plunger chamber (17), to allow the hydraulic oil to pass the plunger valve (18) into the compression chamber (25), supplying control oil at a working test control oil pressure to the plunger piston (16) and via the control oil channel (30) to the nozzle piston (41), said working test control oil pressure being equal to or higher than a predetermined working control oil pressure required for the nozzle piston (41) to open the nozzle valve (38) and for the plunger piston (16) to compress the hydraulic oil in the compression chamber (25) to deliver a pressure being above the pressure required for opening the suction valve (32) and checking whether any of the supplied hydraulic oil reaches out from the nozzle openings (46).