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Марто,
Тези пеперудки във всмукателния колектор имат ролята да променят дължината на смук. колектор.
Ниски обороти голяма дължина
Високи обороти къса дължина
Ето малко инфо за тази система на Форд:
Intake Manifold Runner Control
The Intake Manifold Runner Control (IMRC) system has been used on Ford and Mazda engines in several forms. One early form (actually,
a predecessor to the modern IMRC system) was first used on the Taurus 3.0-L Super High Output (SHO) engine, beginning with its introduction
in the 1989 model year, and then was used on the Taurus 3.4-L SHO engine. This engine is a 24-valve V6 with two intake valves and two exhaust
valves per cylinder. A long intake runner supplies air to one intake valve during normal engine RPM and load conditions. A short intake
runner supplies air to the other intake valve, but it is allowed to do so only during high engine RPM and load conditions. During low RPM and
load operation, a valve within the short runner is closed, inhibiting air flow through it. This design allows for good air flow velocity through the intake
system and into the cylinders during low RPM and load conditions, resulting in good throttle response and greater fuel economy. However, by
opening up the second runner during high RPM and load conditions, a greater quantity of air is allowed into the cylinders when it is needed
for all-out performance without sacrificing the low-end throttle response. Modern IMRC systems, as they are used on both Ford and Mazda engines, use a valve to lengthen or shorten the effective length of the intake manifold runner, depending upon engine RPM and load conditions. At low engine RPM
and load conditions, the valve closes off a “shortcut,” thereby effectively lengthening the intake manifold runner and making for good throttle
response. At high engine RPM and load conditions, the valve opens up the shortcut, thereby effectively shortening the intake manifold runner
and allowing additional air to be brought into the cylinders when more power is needed. The valve may be operated electrically by the PCM or may
be operated with vacuum actuation. Another variation of the IMRC system was a Split Port Induction (SPI) system that was used
on 2.0-L Escort engines beginning in the 1998 model year. This engine has intake manifold runners of different diameters. The larger-diameter
runner was closed off at engine speeds below 3000 RPM, using only the smaller-diameter runner to keep air velocity high. Above 3000
RPM the larger-diameter runner is also opened up, allowing for additional air to fill the cylinders. Even though this engine only has two valves per
cylinder, its performance approaches that of engines having multiple valve heads. The following are advantages of these designs:
• the ability to allow smaller engines to produce
more power when it is needed without sacrificing
low-end performance and throttle response
• the ability to sustain good low-end throttle
response, greater fuel economy, and better
emissions without sacrificing high-end all-out
power