Woodward SOGAV 250 solenoid valve drives gas intake valve for troubleshooting

The cable length and diameter should match: 1 mm ² (18 AWG) for cables not exceeding 15 meters, 1.5 mm ² (16 AWG) for cables between 15-25 meters, and 2 mm ² (14 AWG) for cables between 25-40 meters. The wire from LECM to the valve does not require shielding, but it must be twisted pair, at least 30 twists/meter, and the insulation outer diameter must meet the LECM joint sealing requirements. No live plugging or unplugging is allowed in hazardous areas; The on-site wiring should withstand at least 105 ° C; the coil grounding terminal should be grounded.

Four step bench testing for rapid isolation issues

When suspecting a problem with Sogav 250, first remove the valve and perform four tests in sequence. If all four items pass, the problem is likely not with the valve, so do not continue to disassemble.

The first step is to measure the coil resistance. At room temperature, measured from the two pins of the connector, the MS connector and flying wire version of Sogav 250 are both 1.1-1.3 Ω, with slight differences in flying wire length. Due to the low resistance, the probe resistance must be deducted; It can also be compared with known good valves. If it exceeds the range, replace the E-core coil component. Measure the resistance from any needle to the electromagnet housing again, which should be infinitely high; Sometimes the initial reading is greater than 10 M Ω and gradually rises to infinity, indicating that the meter is charging the coil capacitor, not a fault. If low resistance occurs, it indicates a short circuit to ground, and the coil component should be replaced.

The second step is to conduct a valve leakage test. Install a pressure connector and a suitable O-ring at the air inlet, add 150 kPa/1.5 bar of air, and listen to the outlet in a quiet place. If you cannot hear or only hear reluctantly, the valve is normal; If there is a significant leakage, it may be due to damage to the valve plate or contamination between the plates, and it needs to be disassembled for inspection and treatment. The flow meter should be less than 2.83 m ³/h (100 SCFH).

Step three, measure the intensity of the action. Apply 150 kPa/1.5 bar air pressure, use a power supply that can output 16 A and 110 VDC, limit the current to 16 A, and limit the voltage to be greater than 110 VDC, with a series switch. After the switch is instantly turned on and immediately turned off, hearing a loud "bang" sound like a balloon bursting indicates sufficient power. Note that the power on of 16A should not exceed 2 seconds; Two rapid and continuous 1-second pulses are equivalent to one 2-second pulse, with a 1-minute cooling interval between the pulses. The actual In Pulse driver can only be powered on for a maximum of 0.0032 seconds at 16 A each time, which cannot be achieved by manual switching, so strict time limits must be implemented. If there is no loud "bang" sound and the current is applied correctly, it may be due to loose screws between the armature and the dynamic measuring plate, foreign objects between the dynamic plate and the upper plate, or foreign objects between the armature and the E-core, which should be disassembled for inspection and evaluation.

Step four, measure the valve stroke. Bottom load version only: First confirm that the outlet seat ring is flush with the valve housing surface. Set the power current limit to 6 A without adding air pressure. After the switch is turned on, quickly reduce the current to 2 A (2 A can be continuously powered on without overheating). Measure from the valve bottom flange to the dynamic measuring plate surface using a depth micrometer or dial gauge; After the power is cut off, the difference is the stroke, which should be 0.49-0.52 mm. The diameter of the measuring rod is less than 3 mm, and it extends into the outlet hole of the lower stop measuring plate, passes through the panel slot, and touches the plate surface. If the stroke is less than 0.48 mm, it is likely that there are foreign objects between the moving plate and the upper plate or between the armature and the E-core; If it is greater than 0.52 mm, there may be wear and tear, and it should be disassembled for inspection and evaluation.

Four items still pass abnormally, check again: whether the pressure difference between the two ends of the valve exceeds 150 kPa/1.5 bar, overpressure will prevent suction; Whether the cables and joints are in good condition, and the resistance of each wire should be less than 0.4 Ω; Whether the wire is eroded, whether the joint is loose or intermittent; Are the controller timing and driver settings correct.

Application system and pressure difference limitation

The maximum pressure difference from the gas manifold to the air manifold of Sogav 250 unbalanced valve is 150 kPa/1.5 bar, beyond which the valve may not open. At low loads, the pressure difference should be small to avoid a very short opening duration, which can lead to a decrease in mixing uniformity and an increase in valve to valve differences; At full speed and load, a high pressure difference is usually required to supply sufficient fuel within the allowed time. If the load drops significantly without reducing the gas manifold pressure, the pressure difference may exceed the limit and the valve will not work. Therefore, the main engine controller must simultaneously control the air manifold pressure and gas manifold pressure: the air pressure is controlled by the throttle/actuator or exhaust bypass to control the air-fuel ratio, while the gas pressure regulation ensures reasonable pressure difference under different operating conditions.