Environmental Engineering Reference
In-Depth Information
Schematic yaw system
FIGURE 2.9
Schematic.yaw.system.
The. modern. yaw. drives,. even. though. electronically. controlled. and.
equipped. with. large. electric. motors. and. planetary. gearboxes,. have. great.
similarities.to.the.old.windmill.concept..They.still.use.a.means.of.mechani-
cal.energy.“production”.(i.e.,.electric.motor),.a.method.to.increase.the.torque.
(i.e.,.gearbox),.and.a.gear-rim.mounted.on.the.ixed.portion.of.the.wind.tur-
bine.and.in.constant.mesh.with.the.output.gear.of.the.said.gearbox.
2.7.2
Components
(See.the.schematic.yaw.system.shown.in.Figure 2.9.)
2.7.2.1 Gearbox
The.gearbox.of.the.yaw.drive.is.a.very.crucial.component.since.it.is.required.
to. handle. very. large. moments. while. requiring. the. minimal. amount. of.
maintenance.and.also.to.perform.reliably.for.the.whole.wind.turbine.life.
span.(approximately.20.years)..Most.of.the.yaw.drive.gearboxes.have.input-
to-output. ratios. in. the. range. of. 2000:1. in. order. to. produce. the. enormous.
turning.moments.required.for.the.rotation.of.the.wind.turbine.nacelle.
2.7.2.2 Gear Rim and Pinions
A. planetary. gearbox. reducer. is. illustrated. in. Figure 2.10,. depicting. a. sche-
matic.representation.of.a.gear.rim.with.teeth.on.the.inner.side..The.gear.rim.
meshes.with.four.yaw.drive.pinions.
13
The.gear.rim.and.the.pinions.of.the.yaw.drives.are.the.components.that.
inally. transmit. the. turning. moment. from. the. yaw. drives. to. the. tower. in.
order.to.turn.the.nacelle.of.the.wind.turbine.around.the.tower.axis.(z.axis)..
The. main. characteristics. of. the. gear. rim. are. its. big. diameter. (often. larger.
than.2.m).and.the.orientation.of.its.teeth.
The.gear.rims.with.teeth.on.the.outer.surface.have.the.advantage.of.higher.
reduction.ratios.in.combination.with.the.pinions.as.well.as.reduced.machin-
ing.costs.over.the.gear.rims.with.inner.teeth..On.the.other.hand,.the.former.
coniguration.requires.that.the.yaw.drives.be.mounted.far.apart.from.each.
other,.thus.increasing.the.wind.turbine.main.frame.dimensions.and.costs.
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