Cleaning and liquid contact with solids – Processes – Hollow work – internal surface treatment
Reexamination Certificate
2001-11-07
2003-12-02
Gulakowski, Randy (Department: 1746)
Cleaning and liquid contact with solids
Processes
Hollow work, internal surface treatment
C134S022180, C134S022190, C123S00100A, C123S19800E
Reexamination Certificate
active
06655392
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
BACKGROUND OF THE INVENTION
This invention relates to the maintenance of automobile internal combustion engines and, more particularly, to a method and apparatus for cleaning a fuel injected engine plenum through the idle air control port.
In order for automobile engines to function efficiently, it is important that sludge, varnish and other unwanted elements are not allowed to accumulate on the surfaces of the air intake assembly (or plenum). In carbureted and throttle body engines, nearly all areas of the air intake assembly except for the filter itself are constantly in contact with a supply of fog or fuel spray. The throttle plate of the air intake assembly is even sprayed as fuel proceeds to the intake valves and combustion chamber. This spray tends to keep the plenum relatively free from buildup.
However, in port fuel injected engines, fuel is sprayed in close proximity with the intake valves, and is not in a foggy state when it enters the plenum of the air intake assembly. As a result, sludge and varnish tend to coat the inside of the manifold over time. When the engine is shut off, vapors from the combustion chamber rise into the plenum through those intake valves that are either completely open or partially open. Since the plenum is significantly cooler than the crankcase, the vapors condense to form large oil deposits. Also, in many engines, the Exhaust Gas Recirculation System (EGR) dumps particle laden exhaust gas directly into the mouth of the plenum, and hard carbon deposits form within the plenum. The exhaust deposits are concentrated about the port or ports where the particle laden gas enters the plenum.
The vapors cool and condense into particles that collect on the walls of the plenum. The particles include moisture, fuel, oil and exhaust carbon deposits. A thick sludge collects on the flat base of the plenum and the other horizontal surfaces within the plenum. Deposits also form on the walls of the plenum in the form of varnish deposits that are particularly difficult to remove. Additionally, since the throttle plate (or throttle plates) are closed when the engine is shut off, the backside of each plate is coated with harmful deposits of the particles. In addition to these surfaces, the mass air flow sensor, mass air pressure sensor and other sensors become coated with the deposits.
Initially, the designers of port fuel injected engines believed that buildup of deposits would not create a problem due to the substantial size of the plenums in these type of engines. As a result, no provisions were made to allow the plenum to be easily accessible for occasional cleaning. However, the size of the plenum has not prevented the adverse effects of plenum buildup.
The negative consequences of unwanted accumulations of sludge and other contaminants are numerous and severe. For example, the presence of deposits throughout the plenum requires that more air be supplied to idle the engine at the appropriate speed. Briefly, most engines have an Idle Air Control (IAC) System to control the precise amount of air required for the engine to idle at the proper RPM. The IAC System increases or decreases the idle speed under varying load condition to prevent stalling of the engine. The IAC System includes an IAC valve that is positioned in communication with a conduit that bypasses the throttle plate. The IAC valve is mounted at an IAC port disposed along the bypass conduit. The IAC valve is typically a motorized pintle valve having a tapered valve tip that extends or retracts relative to a seat formed in the bypass conduit near the IAC port. When the valve tip is close to the seat, little air is allow around the throttle plate and ultimately into the combustion chamber. When the valve tip is retracted from the seat, more air is allowed around the throttle plate. An IAC sensor located in the plenum sends information to an electronic control module (ECM) that controls the position of the tapered tip of the IAC valve to regulate the volume of air provided to the plenum. The IAC sensor measures the amount of air required to idle the engine at a certain RPM compared to the amount of air required when the vehicle was new. As deposits accumulate within the plenum, more air is required to idle the engine, and the ECM automatically adds more fuel to create a rich condition. This condition leads to poor driving performance, higher emissions and lower fuel economy.
Other engine problems are attributable to a dirty plenum. For example, when deposits accumulate on the various sensors disposed within the plenum, the operation of the vehicle's computers is disrupted since the input information received from the sensors is no longer accurate. Namely, the ECM takes readings from the sensors to control the fuel to air ratio and EGR system. When the sensors are covered with deposits, the engine will operate inefficiently to cause additional performance and emissions problems.
Many attempts have been made to clean the plenums in port fuel injected engines. One method is to coat the inside of the plenum with a special chemical coating. However, these coatings have not proven effective-particularly with recent reformulations of fuel. Another method involves spraying an aerosol cleaning solution at or near the throttle plate. In order for the aerosol spray to reach the depths of the plenum, the aerosol must be sprayed while the engine is running. However, when aerosol is sprayed while the vehicle is running, the vehicle runs at much higher speeds than normal, and numerous problems may ensue. For instance, a vortex sometimes forms near the center of the plenum that pulls the aerosol away from the surfaces of the plenum that require cleaning. Also, when the engine is operating at a high speed, the dry solvent will strip the normal lubricating oil film from the walls of the cylinder, and scoring may occur. Also, aerosols are often difficult to meter properly. Too little aerosol leads to ineffective cleaning, and too much aerosol leads to hydrolocking of the engine since the engine's combustion chamber is not capable of compressing the liquid. The potential for hydrolocking makes it particularly difficult to spray behind the throttle plate with the engine running. Another practical problem is the possibility that the straw secured to the aerosol may be dislodged and drawn into the combustion chamber.
Another method of cleaning the plenum utilizes an atomizing apparatus that creates a fog of cleaner at the front of the throttle plate. The cleansing fog must go around the throttle plate to enter the plenum. However, the throttle plate is completely closed at times when the engine idles and must be opened to allow cleaner to flow into the plenum. When the throttle is opened, the vortex effect may occur and limit the effectiveness of the cleaner. Also, most of these atomizing systems require that the flexible boot between the air filter box and plenum mouth be removed. If the vehicle's computer relies upon a sensor in the boot, removal of the boot may cause the computer codes to be tripped and/or the engine to stop running.
In another method, a cleaning system having its own throttle control is connected to the mouth of the plenum. In these systems, if the cleaning fog is pulled through the IAC conduit and contacts the components of the IAC, serious damage may occur. Also, for many vehicles, the mass air flow sensor is located near the mouth of the plenum instead of the hose connecting the air filter box and the plenum. In these vehicles, the sensor can not be removed to accommodate this cleaning method since the vehicle will not run when the sensor is removed.
One other method involves removal of a plenum vacuum hose and insertion of a small metering tip. When the engine is started, the vacuum formed inside of the plenum draws cleaner from the metering tip. While the problems associated with the engine running at high speeds are generally avoided, the danger
Erwin Harold E.
Leslie Ronald R.
BG Products, Inc.
Chaudhry Saeed
Gulakowski Randy
Shook Hardy & Bacon L.L.P.
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