Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2000-03-06
2001-07-17
Walberg, Teresa (Department: 3742)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S19800E, C477S189000
Reexamination Certificate
active
06260525
ABSTRACT:
CROSS REFERENCE
This application is an improvement of the valve disabler described in my U.S. Pat. No. 5,832,885 issued Nov. 10, 1998. It is incorporated herein by reference.
1. Field of the Invention
The present invention relates to the field of internal combustion engines; more particularly to a method of controlling the engine intake and exhaust valves so as to produce a more efficient combustion process within the cylinder.
2. Background of the Invention
This invention describes a method for increasing the efficiency and reducing the undesirable emissions of an internal combustion engine. While the general principles and teachings disclosed are applicable to all combustion engines, the invention is hereinafter described in detail in connection with its application to a reciprocating, fuel injected, spark ignited, multi-cylinder engine.
As used herein, the term “engine” refers to a device which converts heat energy, released by the combustion of a fuel, into mechanical energy in a rotating output shaft of the engine. Also, the term “disabled cylinder” is defined as having the intake and exhaust valves of a cylinder disabled so that they remain closed while the crankshaft is rotating. These valves may be poppet valves driven by a camshaft common to such engines or any other valves which admit or discharge a gaseous mixture to or from the cylinder. Also, the term “brake specific fuel consumption” or “BSFC” is defined as the amount of fuel consumed to deliver a given energy to the engine drive shaft.
In the United States, the law requires that many types of vehicles must be tested over a specified driving cycle (EPA test) while the fuel consumed and the exhaust emissions generated are measured. This driving cycle has many periods of acceleration, deceleration and idle, with few periods of steady speed, and is intended to reflect typical urban vehicle usage. During deceleration and idle operation it is difficult to control emissions in typical internal combustion engines—particularly throttled engines because of the low manifold pressures at these times. Also, when the accelerator pedal is released, fuel continues to be consumed even though no energy is required from the engine. The emissions measured during this test must be less than those specified by law at the time of manufacture, and the fuel consumed is used in the determination of the vehicle manufacturer's corporate average fuel economy (CAFE).
DESCRIPTION OF THE PRIOR ART
The poppet valve driven by a camshaft has been used in the internal combustion engine for many years. Modifications to the valvetrain have been developed to permit changing the valve timing while the engine is in operation. When the timing control prevents the valves from opening during an engine cycle, the cylinder is disabled, and the effect of a variable displacement engine is obtained. The advantage of a variable displacement engine is that when less than maximum efficiency power is required, some of the cylinders may be disabled and the remaining active cylinders' power is increased so that they will operate at greater efficiency, while the engine output remains constant. This approach has had limited success in practice because the usual control activates or deactivates half the number of cylinders, and this abrupt change in output torque causes poor drivability. Furthermore, the disabling mechanism is relatively slow acting so that more than one revolution of the crankshaft is required to make the change.
All of the differences cited with the prior art referenced in my previous patent (5,832,885) apply to the present invention.
Martin W. Uitvlugt in U.S. Pat. Nos. 4,222,354 and 4,227,494 describes a disabler having a solenoid actuator which disables two engine valves simultaneously only when both valves are closed. The present invention disables the valves individually and can do so whether the engine valve is open or closed. The solenoid of the Uitvlugt disabler must have the power to overcome the friction, spring forces, and inertia of the disabling mechanism in order to disable the two valves. The present invention only requires the solenoid to provide a sealing force for the magnetic circuit since the disabler spring always closes that circuit when the cam lobe has rotated beyond the maximum actuation point.
Robert S. Mueller in U.S. Pat. No. 4,230,076 describes an improvement of the Uitvlugt patents which couples an additional pair of valves to the 1 pair control system. In U.S. Pat. No. 4,256,070, he provides means for utilizing the cyclic forces of the camshaft to power part of the disabling mechanism. This adds friction, spring forces, and inertia to the camshaft load. Further, it adds a delay to the start of disabling because the camshaft must first actuate the mechanism to begin disabling. This means the initial acceleration normally applied to the valve by the cam lobe is applied to the disable assembly when the valve is enabled. In the present invention, the disable spring, which is compressed by the cam during each disabled cycle, closes the magnetic circuit. When the valve is enabled, the enabling solenoid does not need to move anything, it merely seals the magnetic circuit. Further, since the disable spring is weaker than the valve spring, the work load on the camshaft is less rather than more than the normal load.
D. J. Bonvallet in U.S. Pat. No. 4,777,915 describes a disabler mechanism consisting of one solenoid to open the engine valve, and another solenoid to close the same valve. Here again, much electrical power is required because the stroke to open the exhaust valve must begin against the exhaust pressure at bottom dead center (BDC), and the solenoids must power all the repetitive valve operations.
M. B. Diggs in U.S. Pat. No. 5,544,626 uses a solenoid to cause a pin to interfere with the compression of a disabler spring. Although the solenoid is not required to compress the valve spring, it cannot interfere once the disabler spring compression has begun. To disable the valve while the cam lobe is compressing the valve spring requires a strong solenoid. Thus, control of valve overlap, throttling, and exhaust gas recirculation would use more power than in the present invention. The same comments apply to his improvements in U.S. Pat. No. 5,653,198, where there are more components having additional mass.
OBJECTS AND ADVANTAGES
The main object of this invention is to improve the fuel efficiency and reduce the undesirable emissions of the internal combustion engine while powering a vehicle in normal operating conditions. This object is accomplished by varying the timing of the engine intake and exhaust valves. These valves are opened and closed rapidly by the camshaft and the timing of their closure is controlled by a computer which calculates the optimum timing. The computer adjusts the valve timing based upon operator demands and stored engine data to produce maximum fuel efficiency with adequate emission control, uniform engine temperature, and smooth engine operation. This valve control also eliminates the need for the throttle and exhaust gas recirculation valve and their attendant contribution to engine losses.
The object is further accomplished by discontinuing the fuel flow and disabling all the cylinders whenever the accelerator pedal is released and the engine is above idle speed. With no fuel, the engine generates no emissions during this period. When a cylinder is disabled, its intake valve is closed before the end of the intake stroke so that there is enough vacuum when the piston reaches bottom dead center (BDC) that the product of pressure across the piston rings and time integrates to zero. This results in a much lower peak pressure in the disabled cylinder at top dead center (TDC) and reduced friction losses. In order to maintain drivability while achieving the fuel savings, it is necessary for the computer to control the pattern of the disabled and enabled cylinders to insure a quiet, smoothly running engine. This requires a fast acting disabling mechanism with low power consumption and minimum n
Dahbour Fadi H.
Walberg Teresa
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