Woodward SOGAV 250 solenoid valve drives gas intake valve for troubleshooting

In terms of timing, after the overlapping period of scavenging, the Sogav quickly opens after the exhaust valve is closed, and the gas enters the intake duct and enters the cylinder with the air; Control relies on the duration of activation. The valve must be closed early enough before the intake valve is closed, otherwise the gas remaining in the intake duct will be discharged into the exhaust during the next overlap period, wasting fuel and increasing unburned hydrocarbons. Engineers need to determine the opening time and maximum allowable duration, with the valve as close as possible to the intake valve and the connecting passage as short as possible.

When estimating flow rate, the gas flow equation can be used for subcritical flow; When P2/P1 is less than 0.544, it enters the blocked flow and is calculated using 0.544 instead of the actual ratio. For example, when k=1.31, sg=0.55, P1=4.5 bar, P2=3.0 bar, and Tg=20 ° C, the steady-state fully open flow rate is about 538 g/s. This example can be used to determine whether the valve specifications and pressure difference match.

Key points for replacement and maintenance

Confirm the model before replacement: unbalanced bottom load, unbalanced top load, or balanced top load; MS connector or fly wire; Is the coil resistance consistent with the part number. Do not directly swap different structural versions. At least retest after replacement: installation of O-ring, screw torque, grounding, coil resistance, ground insulation, leakage, actuation strength, stroke; The bottom version also needs to confirm that the seat ring is flush. Before the first gas supply, use air or inert gas to check for leaks and confirm that there are no leaks before starting.

The lifespan of Sogav valves is related to speed, fuel quality and pollutants, filtration, temperature, vibration, driving electronics, fuel oil content, and installation direction. The recommended fuel oil content is at least 2 ppm; Below 2 ppm, the coated version should be selected. The maintenance/refurbishment cycle is determined by the engine manufacturer based on the application; The best way is to return to Woodward for refurbishment with specialized equipment and test benches. On site inspections are only allowed and on-site dismantling is not recommended.

In terms of safety, the gas manifold should be immediately depressurized and emptied after the engine is stopped to prevent gas from leaking into the air manifold through the valve, which may cause excessive concentration during the next start-up. Stop the machine immediately upon discovering a leak, blow the fuel system, check for leaks, and repair them; If the leakage source is Sogav, replace the faulty valve. Confirm that there are no leaks and the leak detection system is functioning properly before restarting.

Quick specification check and on-site inspection checklist

Key specifications: Operating temperature range of -20 to+105 ° C for some models, -20 to+95 ° C for some models; Storage range of -40 to+70 ° C; Humidity ≤ 85% non condensing; Protection IP66; At an altitude of 4000 meters, the response time for fully open/fully closed should not exceed 0.0050 seconds; Close the leakage to less than 0.25% of the rated steady-state flow rate; The filtration requirement is an absolute maximum particle size of 5 μ m; The maximum gas supply pressure is 450 kPa absolute pressure; Maximum air manifold pressure 300 kPa absolute pressure; Maximum pressure difference of 150 kPa; The peak of tempering pressure should not exceed 50 kPa above the current gas manifold pressure, and exceeding 2 bar may damage the valve; The maximum gas temperature is 80 ° C.

On site inspection checklist: 1) Work after power and gas outages; 2) Confirm valve model and connector; 3) Check the cleanliness of the O-ring and installation surface; 4) Tighten M10/3/8 and M8 × 1.25 with torque; 5) Reliable grounding; 6) Measure the coil with a resistance of 1.1-1.3 Ω and connect the probe; 7) Measure ground insulation; 8) 150 kPa leakage test; 9) 16A instantaneous actuation test, strictly limited time; 10) Measure the stroke of 0.49-0.52 mm; 11) Check if the pressure difference exceeds 150 kPa; 12) Check that the cable is less than 0.4 Ω and the joint is not corroded; 13) Confirm that the shielding grounding method matches the controller; 14) After shutdown, the gas manifold is depressurized and emptied.

In the order of "safety first, testing later, electrical circuit first, valve body later", Sogav 250's non opening, internal leakage, weak response, abnormal travel, and re inspection after replacement can mostly be quickly located. When passing the four bench tests, attention should be turned to differential pressure, wiring harness, connectors, and controller timing to avoid ineffective valve disassembly.