Warm Up Regulator - Lotus TURBO ESPRIT Service Manual

SECTION LD
Page
15
0-
I n the cold engine condition the plate adopts a position fully opening the by-pass line.
As
soon a s the ignition i s switched on, current flows through the heating coil and
gradually causes the bimetal strip to bend and rotate the plate,reducing the by-pass
aperture.
As
the engine warns, and its heat i s absorbed by the valve body, the heating
effect of the coil
i s
augmented and the plate i s rotated further to fully close the by-pass.
Engine heat alone is sufficient to ensure that the by-pass remains closed when the engine
IS
warm.
LD.10
-
WARM
UP
REGULATOR
I n order to compensate for the condensation of fuel on the inlet tract and cylinder walls
whilst the engine i s running cold, and to maintain driveability until normal running
temperature i s reached, i t
i s
necessary to enrich the fuel/air mixture during this period.
The warm up regulator fulfils this function by reducing the control pressure by an amount
dependent on engine temperature. When the control pressure
i s
reduced, the fuel control
valve i n the distributor is allowed to move further for a given airflow and open a greater
proportion of the metering slits, increasing fuel flow to the iniectorr.
A
ENGINE
COLD
B
NORMAL RUNNING
9 8
TEMPERATURE
I I 1 : _I
1
.
Valve Diaphragm
4.
Valve Spring
7.
Spring
2.
Return to Tank
5.
Bimetal Spring
8.
Aneroic Capsule
3.
Control Pressure
6 ,
Heating Coil
The warm up regulator comists of a flat seat valve controlling the return of fuel from the
control pressure line to the tank.
The valve i s held closed by a coil spring, but this i s
opposed by a bimetallic spring wound with a heating element which i s fed with current
whilst the ignition i s switched on.
When cold, the bimetal spring overcomes the coil spring and opens the valve, such that
the control pressure is low, a.nd the mixture rich o n engine start up.
.
As
the engine runs,
the bimetal spring i s heated, both
by'
i t s heating coil, andby &in& heat absorbed
by
the regulator, and gradually reduces i t s opening force on the valve. Finally, when the
. e n g i n e reaches normal running temperature, the bimetal spring i s sufficiently heated to
l i f t clear of the valve rod so that the control pressure i s controlled only by the coil
spring
.