Internal-combustion engines – Poppet valve operating mechanism – Electrical system
Reexamination Certificate
2000-06-12
2001-11-20
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Electrical system
C251S129100, C251S129150
Reexamination Certificate
active
06318312
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of priority based on German Application No. 19926412.0, filed Jun. 10, 1999, which is incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
The invention relates to a procedure for cooling electromagnetic actuating devices for internal combustion engine valves in which some of a fluid circulating in the internal combustion engine, particularly lubricating oil, is passed through each electromagnetic actuating device (i.e., an actuator).
An electromagnetic valve actuator for an internal combustion engine has immense advantages because of the freedom with respect to the valve control times, i.e., with respect to the pertinent opening and closing points of the valve. However, relatively high forces must be applied for actuation, especially for opening the valve, which necessitates a certain minimum coil and armature size. As a result, it is extremely difficult to accommodate a conventional actuator housing in a modern cylinder head of an internal combustion engine that, for example, drives a motor vehicle. Additionally, when the valves are actuated, a relatively large amount of heat develops in the coils, especially at higher actuation frequencies, which has to be dissipated in a suitable way.
Pure convection cooling of the actuator housing in the surrounding air is insufficient for this purpose, especially when the constricted space conditions just described are taken into account.
German Patent No. 197 14 496 A1 discloses a conventional electromagnetic valve actuator that is fluid cooled. In particular, a cooling channel is provided in an actuator housing through which some of the stream of fluid circulating inside the internal combustion engine is passed as a cooling fluid. This cooling fluid stream may be provided by engine coolant fluid (e.g., the liquid coolant of a liquid-cooled internal combustion engine) or may be derived from the lubricating oil stream of the internal combustion engine. Alternatively, as disclosed in U.S. Pat. No. 3,882,833, the cooling fluid stream may also be passed directly through the actuator, as opposed to passing through cooling channels integrated in an actuator housing.
A percentage of the power developed by the internal combustion engine is lost to circulating the cooling fluid to the actuators, a plurality of which are normally present in an internal combustion engine. This percentage is generally greater when the lubricating oil circulating in the internal combustion engine is used as the cooling fluid, and especially when the lubricating oil is cold and has a higher viscosity, i.e., before the internal combustion engine has warmed-up. It is desirable to keep power losses due to cooling fluid circulation as low as possible in order to minimize fuel consumption of the internal combustion engine.
SUMMARY OF THE INVENTION
The claimed invention is directed, at least in part, to reducing fuel consumption and engine power losses due to circulating cooling fluid. Accordingly, an adjustable valve arrangement varies the amount of cooling fluid passing through an actuator such that critical component temperatures of the actuator are not exceeded.
The claimed invention is also directed to a procedure for varying the amount of cooling fluid passing through an actuator. In addition to determining whether cooling of an actuator is necessary or not, the amount of cooling fluid passed through the actuator for cooling purposes may be adjusted in such a way that a critical (e.g., a maximum) actuator component temperature is not exceeded. This adjustment is performed by means of a suitable valve arrangement that allows a larger or smaller amount of cooling fluid to flow through the actuator as a function of the temperature of the actuator components.
The present invention provides a method of cooling an electromagnetic actuation device for a valve in an internal combustion engine. The method comprises providing a flow of cooling fluid through the electromagnetic actuation device; and varying the flow of cooling fluid such that a critical component temperature of the electromagnetic actuation device is not exceeded.
The present invention also provides an electromagnetic actuation device for a poppet valve in an internal combustion engine. The device comprises at least one coil winding; an electronic control unit electrically connected to the at least one coil winding; a fluid conduit thermally connected to the at least one coil winding; an adjustable fluid valve in fluid communication with the fluid conduit; and a driver mechanically connected to the fluid valve and electrically connected to the electronic control unit. The electronic control unit energizes the at least one coil winding to displace the poppet valve, the fluid conduit provides cooling fluid to dissipate heat generated by energizing the at least one coil winding, the fluid valve regulates cooling fluid flow through the fluid conduit, and the driver adjusts the fluid valve relative to the heat generated by energizing the at least one coil winding.
REFERENCES:
patent: 3882833 (1975-05-01), Longstaff et al.
patent: 5875746 (1999-03-01), Izuo
patent: 6089196 (2000-07-01), Izuo et al.
patent: 197 14 496 A 1 (1998-10-01), None
Bauer Erwin
Bohne Wolfram
Hoerl-Liegl Albert
Loebbering Ferdinand
Lo Weilun
Siemens Aktiengesellschaft
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