Gasoline Check Valve Noise

[hcisrog]

A check valve in an automobile's fuel delivery module (inside the fuel tank) makes a screeching noise in about 10% of the assemblies and the screeching noise is voltage dependent. Any ideas on valve noise design for liquids to minimize noise and references for valve noise design?

 

[GregLocock]

Sorry, no references

If it is only present in 10% of cases then you have a variability problem, not a design problem, most likely. I'd be looking at moulding part lines creating cavitation, and things like that. If you can reproduce the problem on the bench then you should be able to home in on bad parts very quickly.

Alternatively it could be an istalation problem - perhaps some cars strain a vital isolator and create a sound path.





Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[sreid]

1) I think of a check valve as a passive device; where does the voltage come into play?

2)My first thought for a screeching check valve is a leak that set up a "Venturi Oscillation." Fluid flows through a gap, the pressure decreases in the gap causing the gap to narrow which reduces the flow, the pressure increases and the gap opens, etc, etc, etc.

 

[dcasto]

I'd think along these lines. The pump is DC so rpm of pump is varible to voltage. The higher the volts, the more fuel the pump should move. The check valve (if that is it) will have a pressure drop based on volume. The pressure drop should be porpotional to sound. Maybe a way to smoothout the voltage and flow would help.

Are you sure its not a fuel return valve making the loud noises? or it's relief valve?

 

[Tmoose]

higher voltage, more pressure and flow, more screech?

I'd suspect too much pressure drop across the valve, like when we leave the outside faucet cracked (not really off) with certain lawn sprinklers attached, or pressure reducing valves for a steam turbine

http://instrumentation.co.za/article.aspx?pklArticleId=857&pklIssueId=33&pklCategoryId=75

 

[dcasto]

If you doubled the flow through a check valve, what would the pressure drop do? Be the same? Increase? or decrease?

 

[Tmoose]

re flow vs pressure drop - more flow equals more pressure drop, although the effect can be mighty variable.

http://www.boschrexroth.com/country..._downloads/pdf_erl/2-way_cartridge_valves.pdf

The pressure drop vs flow for several types of check valves, with various spring weights is provided at link above. Despite the description of viton seals, the provided views suggest to me the seats are metallic.

First I'd qualify the flows at various voltages of the test pump(s). Then I'd get a couple of noisy valves, a couple of quiet valves, and a Bosch residual pressure valve. Then I'd carefully dissect them, paying attention to things like perfectly reliable free motion of the valve, as-installed spring pressure, (if coil springs) spring wire diameter, number of coils and free length, and details of seat width and the machining adjacent to the seats (sharp edges, burrs, percent seat contact, and anything else I could think of).

I think there maybe too much spring pressure, maybe exacerbated by a seat machining detail or loose or binding pilot

The truth is out there. I mean in there.

 

[dcasto]

good job tmoose