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Internal Combustion Engines

Quick Response Fuel Injector for Direct-Injection Gasoline Engines

[+] Author and Article Information
Motoyuki Abe

 Hitachi Research Lab., Hitachi, Ltd. 832-2, Horiguchi, Hitachinaka Ibaraki, 312-0034, Japanmotoyuki.abe.kc@hitachi.com

Noriyuki Maekawa

 Hitachi Research Lab., Hitachi, Ltd. 832-2, Horiguchi, Hitachinaka Ibaraki, 312-0034, Japannoriyuki.maekawa.jc@hitachi.com

Yoshihito Yasukawa

 Hitachi Research Lab., Hitachi, Ltd. 832-2, Horiguchi, Hitachinaka Ibaraki, 312-0034, Japanyoshihito.yasukawa.uw@hitachi.com

Tohru Ishikawa

 Hitachi Automotive Systems, Ltd. 2520, Takaba, Hitachinaka Ibaraki, 312-8503, Japantohru.ishikawa.ww@hitachi.com

Yasuo Namaizawa

 Hitachi Automotive Systems, Ltd. 2520, Takaba, Hitachinaka Ibaraki, 312-8503, Japanyasuo.namaizawa.ue@hitachi.com

Hideharu Ehara

 Hitachi Automotive Systems, Ltd. 2520, Takaba, Hitachinaka Ibaraki, 312-8503, Japanhideharu.ehara.kz@hitachi.com

J. Eng. Gas Turbines Power 134(6), 062803 (Apr 12, 2012) (5 pages) doi:10.1115/1.4005995 History: Received October 24, 2011; Revised November 10, 2011; Published April 09, 2012; Online April 12, 2012

We developed a new injector for direct injection gasoline engines that reduce the exhaust emissions and help to reduce fuel consumption. The newly developed actuator in this injector has two features. One is a bounceless valve closing mechanism, and the second is quick response moving parts. The first feature, the bounceless valve closing mechanism, can prevent ejecting a coarse droplet, which causes unburned gas emission. The new actuation mechanism realizes the bounceless valve closing. We analyzed the valve motion and injection behavior. The second feature, the quick-response actuator, achieves a smaller minimum injection quantity. This feature assists in reducing the fuel consumption under low load engine conditions. The closing delay time of the needle valve is the dominant factor of the minimum injection quantity because the injection quantity is controlled by the duration time of the valve opening. The new actuator movements can be operated with a shorter closing delay time. The closing delay time is caused by a magnetic delay and kinematic delay. A compact magnetic circuit of the actuator reduces the closing delay time by 26%. In addition, the kinematic delay was improved when the hydraulic resistance was reduced by 9%. As a result, the new injector realizes reduction of the minimum injection quantity by 25% compared to a conventional injector.

Copyright © 2012 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Schematic image of DI injector

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Figure 2

Enlarged view of moving parts

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Figure 3

Valve opening operation

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Figure 4

Valve closing behavior

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Figure 5

Bounce-prevention effect (simulation)

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Figure 6

Bounce-prevention effect (observation)

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Figure 7

Injection quantity characteristics

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Figure 8

Valve motion for minimum injection quantity

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Figure 9

Magnetomotive-force reduction to reach target level

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Figure 10

Improvement in closing delay time

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Figure 11

Hydraulic effect against closing delay time

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Figure 12

Hydraulic flow around moving anchor

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Figure 13

Fuel passage of anchor

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Figure 14

Effect of fuel passage expansion

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Figure 15

Total reduction of closing delay time

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Figure 16

Improvement of injection quantity characteristics

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