Overview
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A solenoid type injector used in engines opens a valve and injects fuel
by moving a plunger with magnetic force created by an electromagnet.The
response for the applied voltage is evaluated to improve the fuel consumption
by maintaining the flow of fuel dispersed by an injector into an engine.Evaluating
ways to reduce the eddy currents to improve the response characteristics
of an injector is advantageous because the eddy currents produced by the
currents slow the response of the injector.
This example presents the use of a magnetic field analysis to obtain the
response characteristics of a solenoid type injector by evaluating ways
to reduce the amount of eddy currents. |
Joule Loss / Current Density Distribution
The Joule loss of each part is indicated in Fig. 1 and the current density
distribution at 1.3 msec when the Joule loss of the core is largest is
indicated in Fig. 2 and Fig. 3.
The Joule loss differs largely especially in the core with a peak that
is reduced by approximately 20 %. The eddy currents are reduced using a
core designed with narrow slots as indicated in Fig. 2 and Fig. 3. |
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Response Characteristics
The response performance of the plunger versus time is indicated in Fig.
4, and the attractive force is indicated in Fig. 5.
The displacement of the plunger is positive in the direction the valve
opens, and the valve is fully open at a position of 0.1 mm. The fuel pressure
of 5 N is constant against the direction of motion. The plunger does not
move right after the current is applied, but rather begins moving when
the fuel pressure exceeds the attractive force as indicated in Fig. 4 and
Fig . 5. The response characteristics and attractive force are improved
by reducing the eddy currents using slots. |
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