Layered diaphragm
A carburetor may have a fuel metering assembly with a metering valve and a metering diaphragm sealed to a body of the carburetor to at least partially define a metering chamber with a portion of the metering diaphragm movable relative to the body to actuate a fuel metering valve. The diaphragm may include a continuous layer, a discontinuous layer, and an intermediate layer received at least partially between the continuous and discontinuous layers and at least partially inhibiting direct contact between the continuous and discontinuous layers. The continuous and discontinuous layers may be different polymer materials and the intermediate layer may be a polymer different than that of the discontinuous layer. The intermediate layer may include voids, segments, or a wire form.
1. A carburetor having a metering system that controls fuel flow from a fuel source to an air-fuel passage, the metering system comprising:
a metering assembly including a metering valve and a metering diaphragm sealed to a body of the carburetor to at least partly define a metering chamber between the metering diaphragm and the body, the metering diaphragm having a portion that is moveable relative to the body to actuate the metering valve, and the metering diaphragm including a continuous layer, a discontinuous layer and an intermediate layer received at least partially between the continuous layer and the discontinuous layer;
wherein the continuous layer is responsive to fluid pressure to move the discontinuous layer to open a metering valve to allow fuel flow from the fuel source into the metering chamber.
2. The carburetor of claim 1 , wherein the intermediate layer includes a periphery trapped between two carburetor bodies and between a periphery of the continuous layer and a periphery of the discontinuous layer.
3. The carburetor of claim 1 , wherein the intermediate layer includes a void, a segment, or a wire form.
4. The carburetor of claim 1 wherein the intermediate layer is formed from a material that is softer than the discontinuous layer.
5. The carburetor of claim 1 wherein the intermediate layer substantially inhibits direct contact between the continuous layer and the discontinuous layer.
6. The carburetor of claim 1 wherein the intermediate layer has portions underlying at least portions of the discontinuous layer and voids complimentary to voids in the discontinuous layer.
7. The carburetor of claim 1 wherein at least portions of the intermediate layer underlying at least portions of the discontinuous layer have a radial width greater than the radial width of the portions of the discontinuous layer they underlie.
8. The carburetor of claim 1 wherein the discontinuous layer includes a portion protecting the intermediate layer and the continuous layer from contact with a metering valve lever.
9. The carburetor of claim 1 wherein the continuous and discontinuous layers are of different materials and the intermediate layer is of a material different than the material of the discontinuous layer.
10. The carburetor of claim 1 wherein the intermediate layer comprises a less abrasive material than that of the discontinuous layer.
11. The carburetor of claim 1 wherein the intermediate layer comprises at least one of a perfluoroalkoxy (PFA), polytetraflouroethylene (PTFE), fluorinated Ethylene Propylene (FEP), polyester, fluoroelastomer, low density polyethylene, nitrile rubber, or polyurethane.
12. The carburetor of claim 1 wherein the intermediate layer has a smoother surface than the discontinuous layer.
13. The carburetor of claim 1 wherein the surface finish of the intermediate layer is not greater than RA 20 microinches.
14. The carburetor of claim 1 wherein the intermediate layer is bonded to the discontinuous layer.
15. The carburetor of claim 1 wherein the intermediate layer has a thickness in the range of 0.0254 mm to 0.381 mm.
16. A carburetor, comprising:
first and second bodies;
a fuel chamber located between the first and second bodies;
a multilayer diaphragm clamped between the first and second bodies, the diaphragm comprising a first layer of discontinuous material, a second layer of a continuous different material and a third layer of material positioned at least partially between the first and second layers of material; and
a fuel flow valve that opens and closes to allow fuel flow into or out of the fuel chamber, wherein the first layer of discontinuous material flexes to selectively actuate the fuel flow valve, and the second layer of continuous material defines a portion of the fuel chamber and moves in response to a pressure differential across the second layer of continuous material, and wherein the third layer of material at least substantially inhibits direct contact of the first layer of material with the second layer of material.
17. The carburetor of claim 16 , wherein the fuel chamber is a metering chamber, the diaphragm is a fuel metering diaphragm, the first layer of discontinuous material flexes and engages a valve lever, and the third layer of material is discontinuous and of a material different than that of the first layer of material.