DESC:ARRANGEMENT OF A MASS AIR FLOW SENSOR IN AN AIR INTAKE SYSTEM

BACKGROUND

FIELD OF THE INVENTION

[001] The present invention generally relates to an air intake system. More particularly, the present invention relates to an arrangement of mass air flow sensor in the air intake system.

DESCRIPTION OF THE RELATED ART

[002] In internal combustion engines, a mass air flow sensor (MAF) is used for accurate measurement of flow rate of intake air for internal combustion engines. The MAF sensor provides an input signal to an engine control unit (ECU) that is used to obtain a desired fuel-air mixture. Maintaining the desired fuel-air mixture is important to achieve optimum engine performance, fuel economy, and reduction of engine emissions. As the input signal, in particular signal-to-noise ratio of the MAF sensor, may be adversely affected by air turbulence, the MAF sensor would preferably be operated with air currents having a uniform speed and minimum turbulence to obtain accurate readings of flow rate of the intake air. Moreover, a suction line for an ancillary assembly, in particular an air compressor, may create high turbulence and noises if an opening of the suction tube is in the vicinity of the MAF sensor. The effects of air turbulence and noises on the MAF sensor can especially cause problems if the air flow rate, for example, during idling of the engine is low. If the suction line is at downstream of the MAF sensor, it would lead to a distortion in the calculation of the desired air-fuel ratio.

[003] EP2169209B1 describes an intake system for internal combustion engines. A suction line is integrated within a drum-shaped air filter on a filtered air side. An air mass measuring device with a sensor, for example according to the principle of hot wire anemometer or on ultrasonic principle, to calculate the quantity of fuel that has to be metered. The air mass measuring device is positioned on the filtered air side in an air intake pipe. As the air intake pipe is positioned inside the filtered air side, only partial surface area of the drum-shaped air filter is used for filtration. This creates restriction of air flow to an air intake of the engine, while many high-performance engines require high air flow rates. Moreover, the suction line may be in the vicinity of the air mass measuring device if the air intake pipe is positioned towards the end of the drum-shaped air filter. When the distance between the air mass measuring device and an inlet of the suction line becomes short, disturbance or turbulence may occur in the air intake, providing difficulty for the air mass measuring device to measure the intake air flow rate with satisfactory accuracy.

[004] EP2602164B1 describes an arrangement of an extraction device for an auxiliary apparatus. A resonance and / or damping volume is formed in a combustion air intake duct. The extraction device for an ancillary assembly is arranged on a combustion air intake line of the combustion air intake system. The extraction device is arranged downstream of an air filter but upstream of a sensor of an air mass meter. A housing forming the resonance and/or damping volume is attached directly to a housing of the air filter of the intake system and communicates accordingly with clean air side of the air filter. The housing of the damping volume requires considerable amount of an additional space. Due to the high level of modularity in engine hood designs, the space allocated for the air filter is limited by vehicle geometry and engine compartment size; hence this arrangement is not optimal in the practical deployment of the air filter with dead volume housing.

[005] Moreover, when the distance between the MAF sensor and an inlet port of the suction line is decreased in an effort to implement an air filter assembly in a small size, this creates a problem that the intake air flow rate cannot be measured with sufficiently high accuracy.

[006] In light of the foregoing, there exists a need for an arrangement of the MAF sensor and the suction line in the air intake system to accurately measure intake air flow rate. Also, there exists a need for an air filter assembly that is structurally compact with its ease in deployment while accommodating the MAF sensor to accurately measure the intake air flow rate.

OBJECTS OF THE INVENTION

[007] An object of the present invention is to develop an arrangement of a mass air flow sensor and a suction member in an air intake system to accurately measure intake air flow rate of an internal combustion engine.

[008] Another object of the present invention is to develop an air filter assembly that is structurally compact while accommodating the MAF sensor to accurately measure the intake air flow rate of the internal combustion engine.

SUMMARY OF THE INVENTION

[009] An air filter assembly for supplying air to an internal combustion engine. The air filter assembly includes a housing having an air inlet and an air outlet. The air filter assembly further includes an air filter, a mass air flow sensor, and a suction member. The air filter has a hollow interior portion and is mounted within the housing. The mass air flow sensor is mounted at the air outlet at a position downstream of the air filter for detecting flow rate of filtered air discharged from the air outlet. The suction member is mounted in the air outlet. The suction member includes an inlet port formed at an end portion of the suction member. The end portion of the suction member extends towards an end of the housing opposite to the air outlet into the hollow interior portion of the air filter. The inlet port formed at the end portion of the suction member is at a position upstream of the mass air flow sensor and within the hollow interior portion of the air filter.

BRIEF DESCRIPTION OF DRAWINGS

[0010] The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. Embodiments of the present invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the scope of the claims, wherein like designations denote like elements, and in which:
[0011] Fig. 1A is a perspective view of an air filter assembly during a filtration mode, in accordance with a first embodiment of the present invention;
[0012] Fig. 1B is a perspective view of the air filter assembly during a cleaning mode, in accordance with the first embodiment of the present invention; and
[0013] Fig. 1C is a cross-sectional view of a suction member of the air filter assembly, in accordance with the first embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0014] As used in the specification and claims, the singular forms “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “an article” may include a plurality of articles unless the context clearly dictates otherwise.

[0015] Those with ordinary skill in the art will appreciate that the elements in the figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated, relative to other elements, in order to improve the understanding of the present invention.

[0016] There may be additional components described in the foregoing application that are not depicted on one of the described drawings. In the event such a component is described, but not depicted in a drawing, the absence of such a drawing should not be considered as an omission of such design from the specification.

[0017] Before describing the present invention in detail, it should be observed that the present invention constitutes an arrangement of a mass air flow sensor in an air intake system. Accordingly, the components have been represented, showing only specific details that are pertinent for an understanding of the present invention so as not to obscure the disclosure with details that will be readily apparent to those with ordinary skill in the art having the benefit of the description herein.

[0018] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the invention.

[0019] FIGS. 1A and 1B illustrate an air filter assembly 100 mounted in an air intake system (not shown) of an internal combustion engine (not shown). The air filter assembly 100 includes a housing 102 having an air inlet 104 and an air outlet 106. The air inlet 104 defines an opening for the introduction of particulate laden air into air filter assembly 100. The air outlet 106 defines an opening through which filtered air exits from the air filter assembly 100. In an embodiment, the air outlet 106 of the housing 102 is an outwardly extending tapered tubular projection. The air inlet 104 is a tubular inlet for allowing the particulate laden air into the air filter assembly 100, according to embodiments of the present disclosure. The housing 102 is closed at its end opposite to the air outlet 106 by a housing cover 108. A plurality of latches 110a-110b disposed around circumference provide for reliable fastening of the housing cover 108 to the housing 102. According to embodiments of the present disclosure, the housing cover 108 is removably latched to housing 102. The plurality of latches 110a-110b may be spring-loaded clamps, which are well known in the prior art. The housing cover 108 may be provided with a particulate collection trap. Moreover, a dust discharge port 112 is mounted to the housing cover 108 to discharge the collected dust. In the preferred embodiment, the housing 102 is formed of a suitable material, such as aluminium, steel, metal, plastic, or polyurethane.

[0020] As shown in Fig. 1B, a front cross-sectional view of the air filter assembly 100 is depicted. The air filter assembly 100 includes an air filter 114 that is mounted within the housing 102. In an embodiment, the air filter 114 is a cylindrical filter element. The air filter 114 has a hollow interior portion 116. In an embodiment, the air filter 114 may be a combination of one or more filter cartridges that are assembled together to form an air filter. Further, the air filter 114 has a first end facing the air outlet 106 and a second end opposite to the air outlet 106, at which end caps (not shown) are mounted thereon. In an end cap at the first end, an opening 118 is formed to discharge air that has passed through the hollow interior portion 116. The air filter 114 is mounted in the housing 102 by fitting the opening 118 to the air outlet 106. A seal (not shown) is provided at an engagement of the opening 118 of the air filter 114 with the air outlet 106 such that the opening 118 is in fluid communication with the air outlet 106 only. An end cap at the second end of the air filter 114 is closed for separating the hollow interior portion 116 from an annular space 120 that is enclosed between an outer surface of the air filter 114 and an inner surface of the housing 102. The air filter 114 may be a cylindrical pleated filter made of materials such as, but not limited to, filter paper and nonwoven fabric. The annular space 120 that is enclosed between the outer surface of the air filter 114 and the inner surface of the housing 102 forms a non-purified air chamber, and the hollow interior portion 116 forms a purified air chamber.

[0021] The air filter assembly 100 includes a mass air flow sensor 122 that is mounted at the air outlet 106. A sensing element (not shown) of the mass air flow sensor 122 is disposed at a position substantially on central or longitudinal axis of the air outlet 106. The mass air flow sensor 122 is designed to generate a detection signal indicative of the flow rate Q of filtered air flowing out of the air outlet 106. In an embodiment, the mass air flow sensor 122 may be a heat-sensitive resistance element or hot wire sensor. The mass air flow sensor 122 is at a position downstream to the air filter 114. The mass air flow sensor 122 is connected to an electronic control unit (ECU) (not shown) to supply an input signal, which is a detection output of the mass air flow sensor 122. Based on the input signal, the ECU performs optimal control of the fuel injection quantity by driving an injector in conformance with the flow rate Q of the filtered air. The ECU arithmetically, according to the principle of hot film anemometry or on the ultrasonic principle, determines the optimal amount or quantity of fuel to be charged into the internal combustion engine on the basis of the flow rate Q and information derived from other sensors, thereby driving the injector at a duty ratio conforming to the fuel quantity optimal for the current operation state of the internal combustion engine.

[0022] The air filter assembly 100 includes a suction member 124 mounted in the air outlet 106. The suction member 124 is a conduit having one end secured to a hole 126 formed in the air outlet 106. The suction member 124 enters into the air outlet 106 via the hole 126 and extends towards an end opposite to the air outlet 106 into the hollow interior portion 116 of the air filter 114. The suction member 124 has an inlet port 128 that is formed at tip of the suction member 124 within the hollow interior portion 116. The inlet port 128 is at a position upstream to the mass air flow sensor 122, according to various embodiments of the present disclosure. The inlet port 128 is opened in an opposite direction to flow of the filtered air through the hollow interior portion 116. The suction member 124 is attached to an air-intake pipe 130. The suction member 124 is mounted at the hole 126 on an inner surface of the air outlet 106, whereas the air-intake pipe 130 is mounted at the hole 126 on an outer surface of the air outlet 106. In an embodiment, the suction member 124 is a cylindrical tube. In various embodiments, the air-intake pipe 130 is both flexible and rigid in nature based on the design requirements for the air filter assembly 100.

[0023] In an embodiment, the suction member 124 is welded to the hole 126 and the air-intake pipe 130 is bolted to the hole 126. Here, the hole 126 has internal threads (not shown) that allows easy installation of the air-intake pipe 130 to the air filter assembly 100. In another embodiment, the suction member 124 and the intake-air pipe 130 are formed as a single pipe-like member. As may be seen, the single pipe-like member would be of L-shape. The suction member 124 and the air-intake pipe 130 may be made of a metal, aluminum, steel, copper, plastic or resin material.

[0024] The suction member 124 serves as an inlet passage for fresh air that needs to be supplied to an auxiliary unit (not shown), in particular an air compressor. The air-intake pipe 130 has an air outlet opening (not shown) which is connected to an intake duct (not shown) of the auxiliary unit, in particular the air compressor. Air compressors are commonly used to provide compressed air for compressed air systems, such as air brakes in commercial and / or motor vehicles. In various embodiments, the air compressor is for a compressed air braking system (not shown).

[0025] As the inlet port 128 of the suction member 124 is disposed at a location upstream of the mass air flow sensor 122, the flow rate Q of the filtered air introduced ultimately into the internal combustion engine can be measured with high accuracy. Moreover, arrangement of the mass air flow sensor 122 and the suction member 124 leads to removal of dead volume space, especially ancillary chamber, developed in prior art systems, thereby reducing the size of the air filter assembly 100. This in turn reduces the size of an air intake system as in order to utilize effectively the space for installation of the internal combustion engine and accessories thereof as well as for the purpose of reducing the manufacturing cost.

[0026] Moreover, the distance between the mass air flow sensor 122 and the inlet port 128 of the suction member 124 should be preferably selected greater than half of the length of the air filter 114, in order to prevent or reduce disturbances or non-uniformities in air stream that flows through the mass air flow sensor 122. The arrangement contributes to the high-accuracy detection of the flow rate Q of the filter air. With the structure described above, the distance from the mass air flow sensor 122 to the inlet port 128 of the suction member 124 is adjusted by an extent corresponding to the length of the air filter 114.

[0027] Furthermore, when the suction member 124 is disposed in close vicinity of the inner surface of the air filter 114 as may be viewed in the Fig. 1B, fluid resistance for the filtered air can be suppressed, whereby the intake air flow rate Q can be detected with more enhanced efficiency. Thus, no deviation or non-uniformity can take place in the air flow along the periphery of the mass air flow sensor 122. The disposition of the suction member 124 closely adjacent to the inner surface of the air filter 114 leads to suppression of the pressure loss in the air intake system.

[0028] In an embodiment, the hole 126 can be enlarged to house a restriction indicator (not shown). The restriction indicator indicates clogging of the air filter 114. The arrangement of suction member 124 and the restriction indicator at the hole 126 leads to space optimization. As may be seen in Fig. 1A, the air filter assembly 100 may be secured through a set of flanges 132a and 132b to the internal combustion engine (not shown). The set of flanges 132a and 132b help in fastening the air filter assembly 100 using a set of bolts (not shown).

[0029] The arrangement of the mass air flow sensor 122 and the suction member 124 in the air intake system allows accurate measurement of the intake air flow rate to the internal combustion engine. The air filter assembly 100 is structurally compact and can be easily installed while accommodating the mass air flow sensor 122 to accurately measure the intake air flow rate of the internal combustion engine. Moreover, the arrangement is advantageous, especially where there is little space available for the installation of the air filter assembly 100.

[0030] Now referring to Fig. 1C, a cross-section of the suction member 124 is depicted to describe the constructional features. As may be seen, the suction member 124 includes an inner periphery and an outer periphery. In the embodiment shown in Fig. 1C, the suction member 124 includes the inner periphery having a circular shape and the outer periphery having an oval shape. In another embodiment, the suction member 124 includes the inner periphery having a circular shape and the outer periphery having a circular shape. The circular or oval shaped outer periphery of the suction member 124 helps in ensuring a laminar flow within the hollow interior portion 116 of the air filter 114, according to various embodiments of the present disclosure.

[0031] The present invention has been described herein with reference to a particular embodiment for a particular application. Although selected embodiments have been illustrated and described in detail, it may be understood that various substitutions and alterations are possible. Those having ordinary skill in the art and access to the present teachings may recognize additional various substitutions and alterations are also possible without departing from the spirit and scope of the present invention. ,CLAIMS:WE CLAIM:

1. An air filter assembly, comprising:

a housing having an air inlet and an air outlet;

an air filter mounted within the housing, the air filter having a hollow interior portion;

a mass air flow sensor mounted at the air outlet, the mass air flow sensor positioned downstream of the air filter for detecting flow rate of filtered air that discharges from the air outlet; and

characterized in that:

a suction member is mounted in the air outlet, the suction member includes an inlet port formed at an end portion of the suction member;

the end portion of the suction member extends towards an end of the housing opposite to the air outlet into the hollow interior portion of the air filter;

the inlet port formed at the end portion of the suction member is at a position upstream of the mass air flow sensor and within the hollow interior portion of the air filter.

2. The air filter assembly of claim 1, wherein the distance between the mass air flow sensor and the inlet port of the suction member is greater than half of the length of the air filter element.

3. The air filter assembly of claim 1, wherein the suction member is attached to an air-intake pipe mounted and extending from the outer surface of the air outlet.

4. The air filter assembly of claim 4, wherein the suction member and the air-intake pipe are formed as a single pipe-like member.

5. The air filter assembly of claim 5, wherein the single pipe-like member is L-shaped.

6. The air filter assembly of claim 1, wherein the air filter is a cylindrical or drum-shaped air filter element.

7. The air filter assembly of claim 1, further comprising a housing cover that is latched at a bottom end of the housing.

8. The air filter assembly of claim 8, wherein the housing cover includes a particulate collection trap and a dust discharge port is mounted to the housing cover to discharge dust collected in the particulate collection trap.

9. The air filter assembly of claim 1, wherein the suction member includes an inner surface having a circular shape and an outer surface having an oval shape.

10. The air filter assembly of claim 1, wherein the suction member includes an inner surface having a circular shape and an outer surface having a circular shape.