Internal-combustion engines – Poppet valve operating mechanism – Electrical system
Patent
1999-01-04
2000-07-11
Lo, Weilun
Internal-combustion engines
Poppet valve operating mechanism
Electrical system
123 9055, 123 906, 2512901, 2512916, F01L 904
Patent
active
060857048
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an electromagnetically operating actuator for actuating intake and/or exhaust valves, for example, of an internal combustion engine of vehicles, by mainly using an electromagnetic force.
BACKGROUND ART
There has been known such a kind of electromagnetically operating actuator as described in conventional art documents, for instance, Japanese Patent Application First Publication (KOKAI) No. 8-21220.
Briefly explaining in accordance with FIG. 16, the conventional electromagnetically operating actuator includes an intake valve 2 slidably moveable in a cylinder head 1 of an engine, and an electromagnetically actuating mechanism 3 for actuating the intake valve 2 to be open and closed.
The intake valve 2 includes a valve head 2a opening and closing an open end of an intake port 4, and a valve stem 2b formed integrally with an upper end portion of the valve head 2a.
The electromagnetically actuating mechanism 3 includes a casing 5 fixed onto the cylinder head 1, a disk-like armature 6 fixed to an upper end portion of the valve stem 2b inserted into the casing 5, and a valve-closing electromagnet 7 and a valve-opening electromagnet 8 which are arranged in an inner-upper position and an inner-lower position within the casing 5 and attractively move the armature 6 to close and open the intake valve 2.
Installed between an upper wall of the casing 5 and an upper face of the armature 6 is a valve-opening spring 9 which biases the intake valve 2 in such a direction as to open the intake valve 2. A valve-closing spring 10 is installed between a lower face of the armature 6 and a bottom surface of a spring-seat groove formed on an upper face of the cylinder head 1, which biases the intake valve 2 in such a direction as to close the intake valve 2. Further, the electromagnets 7 and 8 have coils receiving a control current output generated from an electronic control unit 12 via an amplifier 11, respectively.
The electronic control unit 12 is adapted to control an amount of energizing each of the electromagnets 7 and 8 depending on detection signal outputs generated from an engine speed sensor 13 and a temperature detection sensor 14 for the valve-closing electromagnet 7. Reference numeral 15 denotes a power source.
The biasing forces of the two springs 9 and 10 and the attracting forces of the two electromagnets 7 and 8 cooperate together such that the biasing forces are accumulated and retained as a potential energy in the springs 9 and 10 and the electromagnetic forces are alternately repeatedly released from the intake valve 2 and applied thereto. The intake valve 2 is thus actuated to be open and closed.
However, in the conventional electromagnetically operating actuator, at the opening and closing timings of the intake valve 2, the electromagnetically attracting forces of the electromagnets 7 and 8 increase beyond the biasing forces of the springs 9 and 10 which act against the attracting forces, respectively. It is likely that the valve head 2a is caused to strongly conflict with a valve seat 4a at the valve-closing timing and that the armature 6 is caused to conflict with the valve-opening electromagnet 8 at the valve-opening timing.
Referring to FIGS. 17A and 17B, a theory of increase of the attracting forces of the respective electromagnets 7 and 8 is explained. FIG. 17B shows characteristics of the electromagnetically attracting forces and characteristics of the biasing forces of the springs 9 and 10 at the opening and closing timings of the intake valve 2. First, when the intake valve closes, the attracting force of the valve-closing electromagnet 7 causes the armature 6 to move upward. Therefore, the valve-closing spring 10 is expanded as the intake valve 2 slidingly moves upward, while the valve-opening spring 9 is compressed to increase the biasing force to be accumulated therein.
Next, when the intake valve opens, OFF signal (disenergizing state signal) is transmitted to the valve-closing electromagnet 7 while ON signal (energizing state signal) is transm
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patent: 4942854 (1990-07-01), Shirai
patent: 5117213 (1992-05-01), Kreuter et al.
patent: 5161494 (1992-11-01), Brown, Jr.
patent: 5636601 (1997-06-01), Moriya
patent: 5772179 (1998-06-01), Morinigo et al.
Lo Weilun
Unisia Jecs Corporation
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