Flow guiding structure for an internal combustion engine

A flow guiding structure for guiding into a clockwise swirling flow pattern gas flowing into a gas passageway leading toward a combustion chamber of an internal combustion engine. The structure includes a tubular peripheral wall having a base section for securing the structure to the gas passageway and an integrally extending guiding section. A plurality of guiding vanes extend radially inward from the guiding section each about a corresponding vane first edge. Each guiding vane includes a vane second edge extending in a geometrical plane perpendicular to the structure longitudinal axis. Each guiding vane further includes a substantially convex vane third edge. The guiding section is provided with a plurality of guiding bents formed therein and extending radially inwardly. The guiding bents are adapted to act as an auxiliary guide and as reinforcement for the structure.

FIELD OF THE INVENTION

The present invention relates to the general field of internal combustion engine accessories and is particularly concerned with a flow guiding structure for guiding into a predetermined flow pattern a volume of gas flowing into a gas passageway leading towards a combustion chamber of an internal combustion engine.

BACKGROUND OF THE INVENTION

As is well known in the art, internal combustion engines produce mechanical power from the chemical energy stored in hydrocarbon fuel. This energy is released by oxidising or burning fuel within the cylinders of the engine.

The amount of power released from the fuel is function of the degree of oxidation and, hence, is dependent on the amount of oxygen available during combustion. As a general principle, the greater the degree of oxidation of the fuel, the higher the efficiency and the greater the power output, reflected respectively by the gas mileage and horsepower of a vehicle.

Three major pollutants typically result from combustion of hydrocarbon in internal combustion engines. These pollutants are oxides of nitrogen, oxides of carbon and hydrocarbon. Carbon dioxide is generally considered a non-toxic necessary by-product of the hydrocarbon oxidation process.

With respect to the nitrogen oxide emissions, their formation is understood to be largely a function of combustion temperatures. However, it is presently understood that leaner fuel-air mixtures and improved mixing of fuel and air may tend to reduce the formation of nitrogen oxides.

With respect to carbon monoxide and hydrocarbon emissions, it is understood that increased oxidation during combustion tends to reduce the formation of these compounds by way of oxidation.

A conventional method for reducing emissions to the environment of the by-products of internal combustion engines oxidation is to use so-called catalytic converters. Catalytic converters however suffer from numerous drawbacks. For example, they are relatively costly and their effectiveness is reduced over time. Hence, they require periodical inspection and replacement to maintain performance.

The life-span of conventional catalytic converters is understood to be a function of the amount of pollutants (primarily unburned hydrocarbons) the device has processed. Accordingly, in addition to increasing the efficiency and power output of combustion, increasing oxidation during combustion is also likely to increase the life-span of the conventional catalytic converters.

As is also well known in the art, reciprocating engines of the Wankel-type typically include a piston mounted for reciprocating or back and forth movement in a cylinder. The piston transmits power through a connecting rod and crank mechanism to the drive shaft. The majority of reciprocating engines operate on what is called a four-stroke cycle, i.e. each cylinder of the engine requires four-strokes of its piston or two revolutions of the crank shaft to complete the sequence of the cycle which produces one power stroke.

The first stroke is termed an intake stroke. It starts with the piston at the top centre crank position and ends with the piston at the bottom centre crank position. As the piston moves from the top to the bottom centre crank position, fresh intake mixture generally comprised of air or air and fuel is drawn into the cylinder through an inlet valve. The inlet valve typically opens just before the stroke starts and closes shortly after it ends.

Whether the intake mixture drawn into the cylinder is comprised of air or an air and fuel mixture is dependent on the engine. For example, in a typical spark emission engine, air passes through an air filter and then is mixed with fuel in the intake system prior to entry to the engine using a carburetor or fuel injection system. The air-fuel mixture is then drawn into the cylinder via the intake valve during the intake stroke. In comparison, a compression ignition engine inducts air alone into the cylinder during the intake stroke and the fuel is directly injected into the engine cylinder just before combustion.

Within internal combustion engines found on most vehicles, the engine takes in large volumes of air at a relatively rapid rate which is then conducted to Venturis within a carburetor is to be mixed with vaporised gasoline and then conducted within the firing cylinders of the engine.

At present, carburetors manage to vaporise approximately 40% of the gasoline in the air and this slow vaporisation rate results in incomplete and inefficient combustion of the gasoline in the engine cylinders, resulting in relatively poor gasoline mileage for the vehicle being driven and relatively high output of combustion products or pollutants.

The use of means for improving the degree of oxidation of the fuel in an internal combustion engine has long been known. For example, in order to increase the volume of the intake mixture into the combustion chamber of internal combustion engines, devices such as turbo-chargers and super-chargers are sometimes used. Although somewhat useful, such devices suffer from numerous drawbacks including that they are relatively expensive to manufacture and service. Furthermore, they draw usable power from the engine and are prone to wear. Still furthermore, they require space within the engine compartment for mounting and increase the overall weight of the motor vehicle.

Another type of means used for improving the degree of oxidation of the fuel in an internal combustion engine includes positioning a structure within the fuel/air stream prior to entry within the firing cylinders so as to cause turbulence of the fuel/air stream. The use of such structures allows the air entering into the combustion chamber to be in a swirling or turbulence state. Turbulent air flow provides a more complete and uniform mixture of air/fuel and, hence, improves the combustion of the charge within the combustion chamber.

The prior art has shown some examples of air turbulence generators for internal combustion engines. For example, U.S. Pat. No. 6,158,412 issued to Kelsen and naming J. S. Kim as inventor discloses a device which may be used to create swirling, turbulent flow to the air entering an internal combustion engine and to the exhaust gases therefrom prior to the gases entering an air pollution system.

The device utilises multiple curved and radially angled vanes to force the air into a predetermined turbulent, swirling pattern. For carburator engines, the device is positioned between the air filter and the inlet to the carburettor and on fuel injection engines, the device is positioned at the inlet port of the intake manifold. Within the exhaust system, the device is positioned within the exhaust tubes just upstream of the catalytic converter to force the gases into a swirling and turbulent flow.

U.S. Pat. No. 6,041,753 issued Mar. 28, 2000 to Lyn et al. discloses an intake swirl enhancing structure including a guide shaft and several guide interfaces radially extending from the guide shaft to split a space into several intake passages. Each of the guide interfaces has a curved outer corner near an outlet end of the intake passages to swirl gas flowing through and out each intake passage.

Although somewhat useful, known prior art gas swirling devices suffer from numerous drawbacks. For example, the flow pattern created by prior art gas swirling devices is often considered to be sub-optimal. Also, the proportion of the surface of the guiding vanes being used for effectively guiding the flow of gas is often considered to be too small.

Furthermore, some prior art devices suffer from the particular defect of overcomplexity, with resulting high manufacturing costs and a propensity to require service and/or repair. Some prior art devices also create an undue restriction to the flow of gases.

Accordingly, there exists a need for an improved flow guiding structure. It is a general object of the present invention to provide such an improved flow guiding structure for internal combustion engines.

In accordance with an embodiment of the present invention, there is provided a flow guiding structure for guiding into a predetermined flow pattern a flow of gas flowing into a gas passageway leading towards a combustion chamber of an internal combustion engine, the gas passageway including a passageway delimiting wall and defining a passageway axis, the structure comprising: a substantially tubular peripheral wall delimiting a structure passage, the peripheral wall defining a peripheral wall first edge, an opposed peripheral wall second edge and a passage longitudinal axis; the peripheral wall having a base section extending from the peripheral wall first edge for allowing the structure to be secured to the gas passageway; the peripheral wall also having a guiding section extending substantially from the base section to the peripheral wall second edge for allowing the flow of gas to be guided into the predetermined flow pattern; a plurality of guiding vanes, each extending substantially radially inward from the guiding section about a corresponding vane first edge; each of the vane first edges extending from a first edge proximal end located substantially adjacent the base section to a first edge distal end located substantially adjacent the peripheral wall second edge; at least one of the guiding vanes including a vane second edge extending in a second edge geometrical plane substantially perpendicular to the structure longitudinal axis from the first edge distal end to a second edge distal end; the at least one of the guiding vanes also including a vane third edge extending from the second edge distal end to the first edge proximal end.

In accordance with an embodiment of the present invention, there is also provided flow guiding structure for guiding into a predetermined flow pattern a flow of gas flowing into a gas passageway leading towards a combustion chamber of an internal combustion engine, the gas passageway including a passageway delimiting wall and defining a passageway axis, the structure comprising: a plurality of guiding vanes, each extending substantially radially inward from the guiding section about a corresponding vane first edge; each of the vane first edges extending from a first edge proximal end located substantially adjacent the base section to a first edge distal end located substantially adjacent the peripheral wall second edge; each of the guiding vanes including a vane second edge extending in a second edge geometrical plane substantially perpendicular to the structure longitudinal axis from the first edge distal end to a second edge distal end; each of the guiding vanes also including a vane third edge extending from the second edge distal end to the first edge proximal end.

In accordance with an embodiment of the present invention, there is further provided a flow guiding structure for guiding into a predetermined flow pattern a flow of gas flowing into a gas passageway leading towards a combustion chamber of an internal combustion engine, the gas passageway including a passageway delimiting wall and defining a passageway axis, the structure comprising: a substantially tubular peripheral wall delimiting a structure passage, the peripheral wall defining a peripheral wall first edge, an opposed peripheral wall second edge and a passage longitudinal axis; the peripheral wall having a base section extending from the peripheral wall first edge for allowing the structure to be secured to the gas passageway; the peripheral wall also having a guiding section extending substantially from the base section to the peripheral wall second edge for allowing the flow of gas to be guided into the predetermined flow pattern; a plurality of guiding vanes, each extending radially inward from the guiding section, the guiding vanes being configured, sized and positioned so as to guide the flow of gas into the predetermined flow pattern; the guiding section being provided with at least one guiding bent formed therein and extending substantially inward into the structure passage, the at least one guiding bent being configured, positioned and sized so as to act as an auxiliary guide and cooperate with the guiding vanes for guiding the flow of gas into the predetermined flow pattern.

In accordance with an embodiment of the present invention, there is still further provided a flow guiding structure for guiding into a predetermined flow pattern a flow of gas flowing into a gas passageway leading towards a combustion chamber of an internal combustion engine, the gas passageway including a passageway delimiting wall and defining a passageway axis, the structure comprising: a substantially tubular peripheral wall delimiting a structure passage, the peripheral wall defining a peripheral wall first edge, an opposed peripheral wall second edge and a passage longitudinal axis; the peripheral wall having a base section extending from the peripheral wall first edge for allowing the structure to be secured to the gas passageway; the peripheral wall also having a guiding section extending substantially from the base section to the peripheral wall second edge for allowing the flow of gas to be guided into the predetermined flow pattern; a plurality of guiding vanes, each extending substantially radially inward from the guiding section, the guiding vane being configured, sized and positioned so as to guide the flow of gas into a substantially clockwise swirling flow pattern.

Advantages of the present invention include that the proposed structure allows for a flow of gas flowing into a gas passageway leading towards the combustion chamber of an internal combustion engine to be guided into a predetermined flow pattern so as to improve the mixing of air and fuel in the combustion chamber.

The proposed structure allows for the guidance of the intake flow into an optimally configured intake swirl or vortex pattern. The swirl is directed in a clockwise direction and generally radially outwardly. The induction of such an airflow configuration has been found to improve gas mileage, increased horse-power as well as reduced carbon monoxide and hydrocarbon emissions.

It is presently understood that the reason for these results is increase air intake to the cylinder or improved mixing of the fuel and air prior to combustion which is understood to likely result in the improved oxidation of the fuel. It is also presently understood that the increased air intake is likely to be the result of similarities in geometry between the valve head and the swirling air flow or vortex. These similarities may likely result in the valve head opposing less resistance so the intake mixture.

The guiding vanes of the structure are configured, sized and positioned so as to optimize the proportion of the surfaces effectively guiding the flow of gas. Also, the proposed device is provided with auxiliary guiding means for further improving the guiding of the flow of gas. The auxiliary guiding means also act as a structural reinforcement for the proposed structure.

The proposed structure is designed so as to be usable with various types of fuels and various types of engines including naturally aspirated and turbo-charged positive displacement internal combustion engines using carburettors, fuel injection or the like. The proposed device is further designed so as to prevent undue flow restriction which could starve the engine of air and/or cause incomplete combustion and sluggishness.

The proposed device is designed so as to be mountable at various locations including in close proximity to the intake of the combustion engine through a set of quick and ergonomical steps without requiring special tooling, manual dexterity or major alterations to the conventional engine and/or its accessories. The proposed device is designed so as to be easily retro-fitted to existing engines as well as installed with new ones.

Typically, the proposed structure is designed so as to be manufacturable out of an integral piece of material through a set of bending and die-cutting operations. Yet, still furthermore, the proposed structure is designed so as to be manufacturable using conventional forms of manufacturing and conventional materials so as to provide a structure that will be economically feasible, long-lasting and relatively trouble-free in operation.

Optionally, the device allows for various types of swirl energy in the intake air based on characteristics of the engine and other vehicle parameters. For example, a general high swirling motion of the air is needed in the combustion chamber at lower engine operating speeds in order to enhance the fuel/air mixing process while a lower swirling motion of the air is desirable at higher engine speeds during which the swirl energy needed to assist in the mixing process is reduced due to the increased energy derived from the incoming gases at the higher piston speeds.

DETAILED DESCRIPTION

Referring toFIGS. 5 and 7, there is shown a flow guiding structure in accordance with an embodiment of the present invention generally indicated by the reference numeral10. The structure10is shown mounted in the air intake system of an internal combustion engine employing respectively a carburettor12and a fuel injector (not shown). It should be understood that although the structure10is shown being used with specific types of engines, the structured10could be used with any other suitable type of engines without departing from the scope of the present invention, as long as the air intake system of the engine includes a gas passageway leading towards a combustion chamber.

FIG. 5illustrates, by way of example, the typical configuration of an air intake system for an internal combustion engine (not shown) of the type that employs a carburettor12. The air intake system typically includes a gas passageway in the form of an air entry chamber14commonly referred to as a “throat” or “air-horn” leading into the carburettor12. The passageway delimiting wall takes the form of upwardly protruding chamber wall16.

With the air intake system illustrated inFIG. 1, the chamber wall16has a substantially circular configuration. However, the chamber wall may take other configurations such as that of rectangles, squares, semi-circles, ovals or the like as is well known in the art.

An air cleaner housing18is typically mounted to the carburettor12. The air cleaner housing18includes a housing base wall20, a housing peripheral wall22extending from the housing base wall20and a removable housing lid24mountable over the housing peripheral wall22. A wing nut screw26typically releasably secures the housing lid24to the remainder of the air cleaner housing via a threaded stem (not shown) located adjacent the top of the carburettor12.

An air inlet duct30typically extends radially from the housing peripheral wall22in fluid communication with the interior of the air cleaning housing18. As indicated by arrows32, the duct30facilitates and guides radial intake of air into the air cleaner housing18.

An annular air filter34is mounted between the upper surface of the housing base wall20and the inner surface of the housing lid24. The annular air filter34defines a filter top surface36, an opposed filter bottom surface38, an outer circumferential air inlet surface40and an inner circumferential air outlet surface42.

The guiding structure10is configured and sized so as to be mountable between the air outlet surface42of the air filter34and the delimiting wall16of the air entry chamber14. Typically, the structure10is configured and sized so as to fit around the outside of the delimiting wall16of the air entry chamber14in a substantially fit or snug fashion.

Hence, in situations wherein the delimiting wall16has a substantially circular shape, the structure10accordingly has a substantially similar circular shape and, when the delimiting wall16has other shapes, the structure10typically has a corresponding shape. Also, the height of the structure10is typically sized so as to snugly fit within the air cleaner housing18when the lid24is secured to the remainder of the housing18. Typically, the height of the structure10is substantially similar to the height of the air filter34. It should, however, be understood that the device10could have other configurations and be otherwise sized without departing from the scope of the present invention.

FIG. 7, illustrates a portion of an air intake system for a fuel injected internal combustion engine44(only a portion of which is shown) comprising a throttle body46. The air intake system illustrated inFIG. 7, typically includes an air filter unit48(only a portion of which is shown). A mass air sensor (not shown) is pneumatically coupled to the air filter unit48upstream from the latter. An air inlet hose52is pneumatically coupled between the mass air sensor and the throttle body46. Clamps54are typically used to secure the components in position relative to one another.

The guiding structure10is typically mounted in the air inlet hose52substantially adjacent the throttle body46. Alternatively, one or more guiding structures10may be housed within the air inlet hose52. The air inlet hose52is hence adapted to act as the gas passageway into which the predetermined flow pattern will be induced by guiding structure10. The peripheral wall56of the air inlet hose52is hence adapted to act as the passageway delimiting wall for the configuration shown inFIG. 7.

As shown in the examples illustrates inFIGS. 5 and 7, the guiding structure10is adapted to be positioned respectively either outwardly or inwardly relative to the passageway delimiting wall16,56delimiting the gas passageway14,52into which the guiding structure10will induce a predetermined flow pattern. Furthermore, as illustrated in the examples shown inFIGS. 5 and 7, the guiding structure10is adapted to be mounted so that the flow of gas will initially impinge thereon either respectively in a radial or an axial direction relative to the latter.

Regardless of the position of the guiding structure10relative to the gas passageway14,52, or the impinging flow of gas, the guiding structure10typically has substantially the configuration illustrated more specifically inFIGS. 1,3and4. The structure10includes a substantially tubular peripheral wall56delimiting a structure passageway50. Typically, structure passageway50is generally co-extensive with the cross-sectional area of the gas passageway to which it is mounted.

In the embodiment shown throughout the Figures, the peripheral wall56has a substantially circular configuration. However, the configuration of the peripheral wall56may vary without departing from the scope of the present invention. Typically, the configuration of the peripheral wall56corresponds substantially to that of the passageway delimiting wall at the location where the guiding structure10is positioned such as the substantially circular passageway delimiting walls16,56illustrated respectively inFIGS. 5 and 7.

The peripheral wall56defines a peripheral wall first edge58, an opposed peripheral wall second edge60and a passage longitudinal axis62. The peripheral wall56has a base section64extending from the peripheral wall first edge58for allowing the structure10to be secured to the gas passageway14,52. The peripheral wall56also has a guiding section66extending substantially from the base section64to the peripheral wall second edge60for allowing the flow of gas to be guided into the predetermined flow pattern.

The guiding structure10also includes a plurality of guiding vanes68. Typically, the guiding structure10includes approximately five guiding vanes68although the guiding structure10could include any suitable number of guiding vanes without departing from the scope of the present invention.

Each guiding vane68extends substantially radially inward from the guiding section66about a corresponding vane first edge70. Each of the vane first edges70extends from a first edge proximal end72located substantially adjacent the base section64to a first edge distal end74located substantially adjacent the peripheral wall second edge60.

At least one and preferably all of the guiding vanes68include a vane second edge76extending in a second edge geometrical plane substantially perpendicular to the structure longitudinal axis62from the first edge distal end74to a second edge distal end78.

At least one guiding vane68and preferably all guiding vanes68also include a vane third edge80extending from the second edge distal end78to the first edge proximal end72. Typically, the vane third edge80has a substantially convex configuration. Typically, the vane third edge80includes a substantially rectilinear third edge first segment82extending from the second edge distal end78. Typically, the third edge first segment82extends at an angle relative to the vane second edge76generally radially inwardly and away from the second edge geometrical plane.

Typically, the vane third edge80also includes a substantially arcuate third edge second segment84extending from the third edge first segment82to the first edge proximal end72. Typically, although by no means exclusively, the third edge second segment84has substantially the configuration of an arc segment of a circle, an ellipse or the like. The vane first, second and third edges70,76and80together delimit a guiding surface100for guiding the flow of gas contacting the latter.

Typically, although by no means exclusively, the length of the vane second edge76is approximately between ¼ and ¾ that of the vane first edge70. Typically, although by no means exclusively, the length of the vane second edge76is approximately ⅓ that of the vane first edge70. Typically, although by no means exclusively, the third edge first segment82and the vane second edge76form a first segment-to-second edge angle86therebetween, the first segment-to-second edge angle86being typically obtuse.

Typically, although by no means exclusively, the first segment-to-second edge angle86has a value of approximately 135 degrees. Typically, although by no means exclusively, the length of the third edge first segment82is approximately 2.5 times that of the vane second edge76.

As illustrated more specifically inFIG. 4, each of the guiding vanes68is oriented in a vane plane extending radially inward, slanted at a vane-to-axis angle88relative to the structure longitudinal axis62. Typically, although by no means exclusively, the vane-to-axis angle88is selected from a range of between 25 degrees and 75 degrees. Preferably, the vane-to-axis angle88has a value of approximately 45 degrees.

As illustrated more specifically inFIG. 2, the guiding vanes68typically extend generally perpendicularly or normal to the inner surface of the guiding section66. It should, however, be understood that the guiding vanes68can extend with other angular relationships relative to the inner surface of the guiding section66without departing from the scope of the present invention.

Typically, the guiding vanes68are positioned circumferentially and are symmetrically disposed relative to each other. Alternatively, the guiding vanes68could be in a non-symmetrical relationship relative to each other without departing from the scope of the present invention. Also, typically, the configuration, size and angular positioning of the guiding vanes68is typically identical for each guiding vane68. However, such characteristics of the guiding vane68could be different for each guiding vane68or for individual guiding vanes68without departing from the scope of the present invention.

As illustrated more specifically inFIG. 3, the guiding vanes68preferably extend only partway towards the centre of the structure passageway50so as to leave a central channel28clear of any guiding vanes68.

In the embodiment illustrated throughout the Figures, the guiding section66includes a plurality of radial apertures90formed therein. Each of the radial apertures90is in fluid communication with a corresponding guiding vane68for allowing radially flowing gas to penetrate through the radial apertures90into the structure passage58and to be guided by the guiding vanes68into the predetermined flow pattern.

Typically, the radial apertures90are formed by substantially V-shaped notches extending substantially from the peripheral wall second edge60to the base section64. Accordingly, the guiding section66includes substantially triangular guiding section segments92separated from each other by the substantially V-shaped notches forming the radial apertures90. Each of the substantially triangular guiding section segments92includes a virtual segment base94and an opposed segment apex located respectively substantially adjacent the interface between the base and guiding sections66,64and the peripheral wall second edge60.

The vane first edge70typically extends from the segment apex to the segment base94. A segment auxiliary edge96also extends from the segment apex to the segment base94in a substantially diverging relationship relative to the vane first edge70. In the embodiment illustrated throughout the Figures, the segment auxiliary edge96has a substantially arcuate configuration. It should, however, be understood that the segment auxiliary edge96could have a rectilinear configuration or other configurations without departing from the scope of the present invention.

At least one and preferably all of the guiding section segments92are provided with a guiding fold or bent98formed therein. The guiding bents98are configured, sized and positioned so as to act as an auxiliary guide for guiding the flow of gas into the predetermined flow pattern. The guiding bents98are also preferably configured, sized and positioned so as to improve the structural characteristics of the guiding structure10and, more specifically, to structurally reinforce the guiding section66.

The guiding folds or bents98typically extend inwardly into the structure passage58. Typically, the guiding bents98extend in a direction substantially parallel to the vane first edge76. Typically, the guiding bents98extend from a position substantially midway along the segment auxiliary edge96to a position substantially midway along the segment base94. It should be understood that although the guiding bent is shown as having a substantially V-shaped cross-sectional configuration, the guiding bent98could have other configurations without departing from the scope of the present invention.

In use, in the implementation depicted inFIG. 5, the intake air flows through the duct30as illustrated by arrows32. The air then penetrates into the outer circumferential air inlet surface40of the air filter34, is filtered by the latter and exits at the inner circumferential air outlet surface42. The air then impinges upon the vane first edges70of the vanes68and passes over the guiding surfaces100of the vanes68into the structure passageway50where it is guided in a swirling configuration prior to penetrating into the gas passageway14of the carburettor12.

The orientation of the vane second edges76in a geometrical plane substantially perpendicular to the structure longitudinal axis62increases the dimension of the effective guiding surfaces100of the guiding vanes68. Furthermore, the configuration of the vane third edge80also provides additional surface area while retaining adequate structural stability of the guiding section66.

In the implementation depicted inFIG. 7, the intake air passes through and is filtered by the air filter unit48. The intake air then passes through the mass air sensor which measures the quantity of air flow prior to passing through the air inlet hose52. While passing through the air inlet hose or gas passageway52, the air impinges upon the vane second edges76and the third edge first segments82of the guiding vanes68. The guiding vanes68manipulate or guide the air flow into a generally vortex configuration. The intake air then enters the throttle body46where fuel is added prior to induction into the combustion chamber or cylinder of the engine44.

Preferably, the guiding vanes68are configured, sized and positioned so as to guide the flow of gas into a substantially clockwise swirling flow pattern. Preferably, the clockwise swirling flow pattern is also directed substantially radially outward towards the peripheral wall56.

The guiding structure10may be manufactured out of any suitable material such as a suitable polymeric resin or metallic material. In one embodiment of the invention, the guiding structure10is manufactured out of stainless steel.

Typically, the guiding structure10is made out of a unitary integral piece of material. When a metallic material is used, the guiding structure10may be manufactured using the following steps: punching or die-cutting the vane third edge80in a planar sheet of metal; cutting the metal sheet at the peripheral wall first and second edges58,60to form strips of the desired height dimension; bending the guiding vanes68into position at the desired angle about the vane first edges70; cutting the strips into the desired length or number of guiding vanes68; roll-pressing the flat strips into the desired configuration which, for example, may be the general circular configuration illustrated throughout the Figures.

Alternatively, the guiding structure10may be formed integrally with the gas passageway through a suitable manufacturing process such as injection moulding or the like. In such an embodiment, the guiding vanes68may extend directly from the passageway delimiting wall without the need for a tubular peripheral wall.