New concepts in modeling air filters for internal combustion engines.

Ratiu, Sorin ; Birtok-Baneasa, Corneliu ; Alic, Carmen Inge 等

1. INTRODUCTION

The correct filtration of the air flowing inside the cylinders of the internal combustion engine is essential for preserving the good engine's operation in time. The obstruction of various impurities' admission from the atmospheric air significantly lowers the wearing-out of the engine's moving parts. Unfortunately, in addition to its air filtration function, the air filter displays a significant gas-dynamic resistance of the absorbed air. If the air filter is not periodically cleaned and the car runs frequently in a dusty area, both the absorption pressure pa and the filling coefficient r|V are dramatically decreased (Ratiu & Mihon, 2008).

Currently, on the market there are several constructive air filters versions, which differ according to the filtering principle:

* filters with filtering cell;

* inertia filters;

* combined filters. These air filters have the following disadvantages:

* the presence of the filtering element inside the box induces an enhanced gas-dynamic resistance of the absorbed air (generating the phenomenon of insufficient absorption);

* storage of impurities inside the filter affects the self-cleaning feature of the filtering element;

* the filtering element can not be visualized and it has to be dismantled for the impurity level to be checked;

* incapacity of the air filter to significantly increase the speed of the absorbed air;

* incapacity of the air filter to cool the absorbed air;

* impossibility of the air filter to create a slight effect of overfeeding during the functioning of the engine.

2. THE INVERTED SUPER ABSORBING FILTER

The inverted super absorbing filter consists in a cylindrical filtering element, bordered at its front part by an internal diffuser fused to a joint cylinder.

At its rear part, the cylindrical filtering element is embedded concentric-axially (2/3 of its length) in a mono-block complex, which consists of an external diffuser for air collection, followed by a direction-inverter (fig. 1).

For an optimal air collection and absorption yield, the inverted super absorbing filter is set along the car's geometrical axis (www.corneliugroup.ro).

[FIGURE 1 OMITTED]

2.1 The external diffuser for air collection with direction-inverter

Due to its geometry, the external diffuser with direction-inverter (pos. 1, fig. 1) ensures a very good collection, causing the inversion of the absorbed air flux by 180[degrees], which is thus directed through the filtering element towards the internal diffuser (towards the filter's exit). The external diffuser with direction-inverter covers the filtering element (pos. 2, fig. 1) (for 2/3 of its length) up to a very precise distance from the element's exterior, which ensures the collection and air flux' inversion. Cooling radiators are located outside the direction-inverter. The cooling radiators consist of external wings, which cover 80% of the external surface of the direction-inverter. They maintain a low temperature of the direction-inverter and generate, consequently, a thermal equilibrium between the surface of the wall and the absorbed air. As result, the air temperature is significantly decreased before it enters the air filter (www.corneliugroup.ro).

2.2 The filtering element

The filtering element (pos. 2, fig. 1) has a cylindrical shape. It consists of a micron-size cardboard, which forms the side surface of the filtering element (in a radial section, the micron-size cardboard has a W shape). The cardboard ensures a micron-size filtration and is covered on the outside with a millimetre sieve, which allows a rough millimetre size filtration of the air. The micron-size cardboard and the millimetre sieve are fixed at the two open ends by silicone rings, for an optimal sealing and concentric-symmetrical alignment with both the internal diffuser of the front part and the mono-block complex of the rear part.

2.3 The internal diffuser for air acceleration

The internal diffuser for air acceleration has a taper shape and ensures the connection between the contact surface and the joint cylinder (pos. 3, fig. 1). Due to its constructive geometry, the internal diffuser has the capacity to increase the speed of the absorbed air. Taper-shaped cooling radiators are located outside the internal diffuser. Because of their taper shape, they redirect the air flux towards the external diffuser, which allows a concentrated flow of the air and a minimum gas-dynamic resistance. They maintain a low temperature of the diffuser and generate, consequently, a thermal equilibrium between the wall surface and the absorbed air. As result, the air temperature is significantly decreased before it leaves the inverted filter. The purpose of the joint cylinder is to link the air filter to the engine's admission gallery (www.corneliugroup.ro).

The internal diffuser for air acceleration, the filtering element and the mono-block complex (the external diffuser for air collection with direction-inverter) have varying dimensions according to the engine's displacement, so that the bigger the displacement, the larger the diffuser's dimensions and vice-versa. The inverted super absorbing filter improves the filling coefficient and is useful for engines that employ air filters set in the opposite direction of the absorbed airflow (filters set up at the rear of the Bugatti, Ferrari, Lamborghini engines).

3. EXPERIMENTAL STAND

The experimental stand consists in making a simplified filter lay-out. A series of pressure plugs are used, allowing the pressure field to be determined when the air flows over the filter, highlighting its capacity of intake and absorption (Alic, 2001). The static pressure is measured in the external axial collector via the pressure plugs 1, 2, 3, 4, inside the filtering element (at 54 its length) via plug 5, at the internal diffuser's entrance via plug 6 and inside the joint cylinder via plug 7 (fig. 2). All these pressure plugs were designed perpendicular to the airflow. The dynamic pressure is measured at the basis of the internal cone via plug 8, at the internal diffuser's exit via plug 9 and at the internal diffuser's external surface via plug 10 (fig. 2). These pressure plugs were designed axial to the airflow (Panaitescu & Tcacenco, 2001). The measurements were made with the digital manometer TESTO 510 (0-100hPa). A significantly higher collection yield is observed in the presence of the internal cone (fig. 2) compared to when the internal cone is missing.

The following graph shows the effect of the cone's presence or absence on the recorded pressure fields.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

4. CONCLUSION

The inverted super absorbing filter has the following advantages:

* being in direct air contact, the filtering element ensures a minimal gas-dynamic resistance of the absorbed air, therefore increasing the level of absorption and collection of the air, and consequently boosting the air filling coefficient of the engine cylinders;

* possibility of the filtering element's self-cleaning;

* the impurities level on the filter can be readily evaluated: the filtering element can be easily visualized without previously dismantling the filter;

* the speed of the absorbed air both at the entrance and the exit of the filter is considerably increased;

* significant capacity of the air filter to cool the absorbed air;

* the air filter creates a slight overfeeding effect during the engine's operation, which is proportional with the car's speed;

* this air filter fulfils new tasks, in addition to its classical function of air filtration: increases the absorption and collection degree, the speed of the absorbed air, cools down the absorbed air and inverts the air flux by 180[degrees].

In future, the authors will stress the importance of making numerical simulations of the air flow through the filter, for different functioning drives of the thermal engine, both for the urban and outside town traffic. Future studies will focus on making efficient the air flow process through the filter and will be made by "computational fluid dynamics" methods. Also, the aim is to prove by experimental measurements the air's intake effect, and the results will be compared with the ones obtained by numerical methods.

Note:

This article is based on an original idea of author Birtok-Baneasa Corneliu, appreciated in time as follows:

1. Silver Medal at the "37-th International Exhibition of Inventions, New Techniques and Products" Geneva 04.2009, for the invention "Inverted super absorbing filter";

2. Special Award at the "Salon of invention and creative youth research", Bucharest 11.2008 for the paper "Dynamic System of Air Transfer";

3. Gold Medal at "The International Eureka Contest Brussels", 11.2008;

4. Gold Medal at "The International Salon of inventions and new technologies Inventika", Bucharest 10.2008 for the invention "Inverted Super Absorbing Filter";

5. Invention patent. Author--Birtok-Baneasa, C.: INVERTED SUPER ABSORBING FILTER

Patent demand: A/00350 / 12.05.2009, Class: P Application in auto industry.

5. REFERENCES

Alic, C. (2001). Experimental research basis--Theory elements and applications, "Orizonturi Universitare" Publishing House, ISBN 973-8109-43-4, Timisoara, Romania

Cioata, V.G. & Miklos, I.Z. (2009). Computer-assisted designing with Autodesk Inventor, "Mirton" Publishing House, ISBN 978-973-52-0576-8, Timisoara, Romania

Panaitescu, P. & Tcacenco, V. (2001). Fluids mechanics' basis, "Technical" Publishing House, ISBN 973-31-2054-5, Bucharest, Romania

Ratiu, S. & Mihon, L. (2008). Internal combustion engines for road vehicles. Processes and Characteristics, "Mirton" Publishing House, ISBN 978-973-52-0314-6,Timisoara, Romania

*** http://www.corneliugroup.ro-Accessed: 2009-03-18