Internal-combustion engines – Charge forming device – Supercharger
Reexamination Certificate
1998-10-28
2001-09-25
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Charge forming device
Supercharger
C123S184210
Reexamination Certificate
active
06293264
ABSTRACT:
BACKGROUND OF THE INVENTION
In the field of performance vehicles, the advantages of supercharging are well recognized. The addition of several pounds of intake air pressure or boost improves the horsepower and torque output of most internal combustion engines and particularly those used in racing.
An example of a representative supercharger is the system disclosed in the instant inventor's U.S. Pat. No. 5,224,459. Superchargers of this type are belt-driven centrifugal blowers that may be attached to stock engines and are able to boost performance without engine modification.
Under extreme conditions, the limiting factor in the power output is not the volume and pressure of the air which is introduced into the intake manifold on command but the temperature of the intake air. Increase in temperature affects the volumetric efficiency and acts to reduce the number of molecules per liter of intake air, affects the actual mixture, and consequently limits the horsepower output. In addition, higher temperatures of the air/fuel charge during the compression stroke increase the danger of destructive detonation.
In turbocharged internal combustion engines, intercooling and aftercooling are well known. A turbocharger, which is powered by heated exhaust gases, adds heat by conduction through the metal parts to the intake or induction air, in addition to the heat added by compression. Consequently, a variety of different types of intercoolers and aftercoolers have been developed for turbochargers and particularly for compression ignition (diesel) engines. Such cooling arrangements typically are not adaptable to belt-driven centrifugal superchargers.
Attempts have been made in the past to cool the intake air after discharge from non-turbo superchargers before it reaches the intake manifold of the engine. This has been accomplished by employing air-to-air cooling by placing ducting (such as made from heat conducting material) from the supercharger to the intake manifold in an area where the outside passage of air tends to cool the exterior of the duct. Placing cooling fins on metal parts of the supercharger or its ducting is another approach. One further approach has been to add a radiator in the path between outside air flow and the engine compartment, similar to existing engine cooling radiators, and connecting an air to water heat exchanger within the duct from the supercharger to the engine, and providing water-to-air cooling. However, these prior art attempts have not totally fulfilled the need for effective intake air cooling.
Another problem in internal combustion engines is the distribution of intake air to each of the cylinders. This must be as even as possible despite the difference in distance between each cylinder and the air intake source. In the past, addition of most types of superchargers would interrupt or destroy any existing tuning of the intake runners. Addition of an aftercooler in most supercharger installations has not allowed tuning of the intake runners. Intake manifold pressure, flow differences and turbulent airflow tend to adversely affect the power limits achievable within existing engines.
There accordingly remains a need for an effective aftercooler for supercharged internal combustion engines.
BRIEF SUMMARY OF THE INVENTION
I have considered the foregoing problems and limitations in existing supercharger systems and have concluded that it is possible to provide significant cooling and to retain the tuned runners of supercharged air before the air reaches the engine intake manifold with a minimal reduction in boost due to lengthy ducting and exchanger sizing and types. I have also determined that it is possible within the cooling operation to enhance the intake air distribution in order to minimize or eliminate volumetric or pressure differences between cylinders and to minimize unintended and unwanted turbulence at the intake manifold runners.
The invention provides an easily bolted-on aftercooler that does not require significant modifications to the engine other than the removal of the engine manifold and its replacement with the aftercooler and its accessories. A source of cooling water and piping and cooling liquid pump that may be external to the engine compartment completes the cooling system. The source of cooling water is ideally a closed circuit cooling system with its own pump, reservoir and return line. In certain cases, the reservoir made be filled at the beginning of a race sequence with ice water for rapid cooling of intake air. The aftercooler of this invention matches engine manifolds of any number of shapes, including manifolds with rectangular and round ports, or other desired shapes.
Each of these objectives described above is accomplished with an aftercooler system which includes a cover defining an intake chamber or intake plenum, an air-to-liquid heat exchanger and includes a generally internally finned but straight-through air passages extending from the intake plenum into the outlet plenum. The cover communicates between the supercharger output duct and the upper plenum. The heat exchanger rests on a base which includes a outlet plenum and individual intake ports for each cylinder. The entire assembly of the cover with its intake plenum, the heat exchanger, the outlet plenum are preferably secured by through bolts.
Air flow through the heat exchanger is largely symmetrical, i.e., straight top to bottom. That air flow is uniform and straight from the intake plenum, enters uniformly into the heat exchanger, passes to the outlet plenum and then to the intake ports of each cylinder. The outlet plenum contains the openings for the tuned intake runners. This invention not only retains but also enhances the function of the tuned intake runners by reducing turbulence and improving distribution. Indeed, as will be described further below, the heat exchanging material in the heat exchange unit acts to even the air flow, but does not substantially reduce the boost pressure. The symmetry of the heat exchanger allows the connections to the cooling water to be made on either side of the engine. This provides a high degree of flexibility in connecting the source and returns for cooling water. Cooling water flows through plate and fin passages in a double or single pass path from the water intake ports to the water output ports via the U-shaped path on one side of the aftercooler, through the heat exchanger and after a sharp turn, returns to the inlet side. Double pass air to liquid heat exchangers are more effective than single pass. In addition, their use minimizes the side-to-side heat gradient associated with single pass heat exchangers. While use of double pass air to liquid heat exchangers optimizes the invention, their use is not essential.
The heat exchanger is reversible for either left or right side cooling water connections. The cover and its intake plenum are also reversible, left to right, to accept supercharged air ducting from either the left side or right side of the engine. The outlet plenum is interchangeable to match the porting of a particular engine type. Examples are shown in the drawings. It should be recognized that the porting of most engines could be matched by selection of a matching design of the lower manifold of this invention without change of the remainder of the aftercooler.
REFERENCES:
patent: 4236492 (1980-12-01), Tholen
Kamen Noah P.
Kelly Bauersfeld Lowry & Kelley LLP
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