Claims:We claim:

1. A plastic air-intake manifold stiffening with at least one profiled metallic structure to reduce engine surface vibrations and noise levels, wherein the air-intake manifold comprises:

(a) an air intake pipe configured with a plurality of intermediate connections leading to the corresponding plurality of profiled air-distribution tubes adapted to be attached to the respective inlet ports of the cylinder head of a direct injection engine,

(b) a plurality of internally threaded bosses configured at predetermined locations on the plurality of intermediate connections and extending perpendicularly towards the top-cover of the air-intake manifold,

(c) at least one profiled metallic bracket consisting of a plurality of interconnected stiffening arms configured in a predetermined profile adapted to be fastened around the top-cover attachment location for stiffening of the intermediate connections area,

(d) a plurality of supporting legs configured substantially perpendicular to the intermediate connections and extending away from the top cover attachment location, each supporting leg provided with through holes for attachment of the respective threaded bosses on the intermediate connections, and

(e) a plurality of fasteners for fastening the metallic bracket configured with supporting legs at the respective threaded bosses configured at the predetermined points on the intermediate connections of the profiled metallic structure.

2. Stiffened plastic air-intake manifold as claimed in claim 1, wherein the profiled metallic bracket is configured as a triangular bracket configured with a plurality of interconnected stiffening arms and at least four supporting legs disposed under the joints thereof and extending towards the respective threaded bosses for fastening the metallic bracket thereon.

3. Stiffened plastic air-intake manifold as claimed in claim 2, wherein the supporting legs are configured on the triangular metallic bracket such that one leg is supported on a corresponding threaded boss configured on the air-intake pipe side of the intermediate connections and the remaining three supporting legs are supported on the other three corresponding threaded bosses disposed on the distribution tube side of the intermediate connections.

4. Stiffened plastic air-intake manifold as claimed in claim 2, wherein the triangular metallic bracket weighs approximately 10 to 20% of the weight of the plastic air-intake manifold.

5. Stiffened plastic air-intake manifold as claimed in claim 1, wherein the metallic bracket is configured circular, oval, rectangular, square or in any other shape and with a plurality of straight, curved or profiled stiffening arms of any size and cross-section.

6. Stiffened plastic air-intake manifold as claimed in claim 1, wherein the metallic bracket is adapted to the dimensions of the weakest portion of the plastic air-intake manifold of different models.

7. Stiffened plastic air-intake manifold as claimed in claim 1, wherein the metallic bracket is made of steel, e.g. mild steel.

8. Stiffened plastic air-intake manifold as claimed in claim 1, wherein the metallic bracket is made of cast aluminum.

9. Stiffened plastic air-intake manifold as claimed in claim 1, wherein the supporting legs are configured integral to the metallic bracket, for example by welding or casting.

10. Stiffened plastic air-intake manifold as claimed in claim 1, wherein the bosses are configured integral to the metallic bracket, for example by welding or casting and subsequently internally threaded.

Dated: this day of 21st August, 2015. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT , Description:FIELD OF INVENTION

The present invention relates to the reducing noise, vibration and harshness (NVH) of the air intake manifold in an automobile engine. In particular, the invention relates to optimizing the plastic air intake manifold (AIM) in automobile engine. More particularly, the invention relates to a profiled metallic structure for stiffening plastic air-intake manifolds in direct injection engines.

BACKGROUND OF THE INVENTION

With the advent of improved properties of various plastic materials, the plastics are playing an ever-increasing role in the areas, which were earlier dominated by the application of metals and alloys. This is particularly true for automotive components. One of the important characteristics of plastics is its low-weight and ease of manufacture due to excellent suitability for moulding intricate designs. This also leads to less material wastage and even the materials obtained as scraps can be reworked and remoulded for manufacturing other components.

One area in automobile application, where plastic is fast replacing the metallic components/subassemblies is air-intake manifolds in direct injection engines. The main function of the intake manifold is to uniformly distribute air to each intake port in the cylinder heads of a direct injection engine. This uniform distribution is very important for optimizing the efficiency and performance of the direct injection engines. This air-intake manifold may also be used as a structure for mounting the carburetor, throttle body, fuel injectors and other components of the engine. Plastic is now being preferred for the simple reason that aluminum or cast iron conventionally used for producing air-intake manifolds is quite expensive and weighs substantially more than the plastic materials. However, plastics being weaker than the metals in terms of mechanical properties, an optimum solution has to be achieved for meeting demanding operational and well as customer satisfaction, e.g. acceptable engine noise levels. Therefore, the engine surface vibrations should not only be within statutorily prescribed levels, but in fact, they should be much lower than that for favorable customer experience. Air-intake manifold is one of the most important engine components, which has a great contribution in controlling the levels of engine NVH (Noise, Vibration, and Harshness). The problem with plastics being used for AIMs is not only their poor acoustical properties as compared to the metallic AIMs, but their low density and stiffness are also a challenge for the designers of plastic air-intake manifolds. For this purpose, the air-intake manifolds made of plastics have to be stiff enough to avoid excessive vibrations, which greatly affect the engine NVH levels.

DISADVANTAGES WITH THE PRIOR ART

During testing with the currently available engines, the vibration levels of the air-intake manifold were measured and found to be beyond the desirable limits. Subsequently, the surface vibration levels of the air-intake manifold were specifically measured and found to be excessively higher than the target values. The design of the air-intake manifold was also weak in terms of the NVH properties thereof. Therefore, it was felt necessary in order to reduce the vibration levels and to meet the targeted levels that the AIM needs to be strengthened by suitable means. The conventional method for improving the NVH performance of any air-intake manifold was to use local stiffening, changing the material or changing the design itself. Out of the abovementioned three possible options contemplated, neither changing the material nor changing the design is feasible at a later stage of AIM design and may demand substantial costs to implement. The local stiffening of air-intake manifold increases the weight of the AIM, which is not favorable due to weak material strength of plastics and due to several manufacturing constraints. Therefore, there was an existing need for improving the design of the air-intake manifolds for automobile engines by suitable stiffening of AIM structure.

DESCRIPTION OF THE PRESENT INVENTION

The characteristics of the vibration behavior of any component are based on its modal characteristics, which in turn depend on the shape, mass and stiffness of the structure thereof. Since plastics have weaker mechanical strength, they are prone to higher modal density and higher vibration levels as compared to the similar components made of any other conventional materials, such as steel or aluminum. This higher modal density along with higher modal displacements causes relatively higher vibrations over the surface of the components. Therefore, in order to reduce the excessively higher vibration levels of the plastic air-intake manifolds, an attempt is made further stiffen the area of the AIM prone to high NVH levels by using a steel-beam structure fastened to the air-intake manifold adjacent the location of the top cover attachment, however without carrying out any structural design changes in the air-intake manifold itself. Attaching this steel-beam structure at the top cover attachment as an additional stiffener has resulted in excellent improvement in the surface vibration levels.

The addition of this steel beam-structure in accordance with the present invention has also increased the stiffness of the base plastic AIM. This has also reduced the modal density and thus the modal displacements thereof, which in turn has caused a substantial reduction in the vibration response of the air-intake manifold. Therefore, the drawbacks of the local stiffening of air-intake manifold are also successfully obviated, while the use of plastic materials was successfully implemented, which resulted in a significant weight-reduction and thereby overall cost reduction in the AIM and thus the entire cost of the automotive engines.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide a plastic air-intake manifold, which meets the desirable NVH levels.

Another object of the present invention is to provide a plastic air-intake manifold, which is can be implemented even at a later stage of designing.

Still another object of the present invention is to provide a plastic air-intake manifold without any change in the structural design thereof.

Yet another object of the present invention is to provide a plastic air-intake manifold, which can be easily adapted to different desirable NVH levels or various engine models simply by changing the stiffener structure thereof.

These and other objects and advantages of the present invention will become more apparent from the following description when read with the accompanying figures of drawing, which are, however, not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a plastic air-intake manifold stiffened with at least one profiled metallic structure to reduce engine surface vibrations and noise levels, wherein the air-intake manifold comprises:

a) an air intake pipe configured with a plurality of intermediate connections leading to the corresponding plurality of profiled air-distribution tubes adapted to be attached to the respective inlet ports of the cylinder head of a direct injection engine,

b) a plurality of internally threaded bosses configured at predetermined locations on the plurality of intermediate connections and extending perpendicularly towards the top-cover of the air-intake manifold,

c) at least one profiled metallic bracket consisting of a plurality of interconnected stiffening arms configured in a predetermined profile adapted to be fastened around the top-cover attachment location for stiffening of the intermediate connections area,

d) a plurality of supporting legs configured substantially perpendicular to the intermediate connections and extending away from the top cover attachment location, each supporting leg provided with through holes for attachment of the respective threaded bosses on the intermediate connections, and

e) a plurality of fasteners for fastening the metallic bracket configured with supporting legs at the respective threaded bosses configured at the predetermined points on the intermediate connections of the profiled metallic structure.

Typically, the profiled metallic bracket is configured as a triangular bracket configured with a plurality of interconnected stiffening arms and at least four supporting legs disposed under the joints thereof and extending towards the respective threaded bosses for fastening the metallic bracket thereon.

Typically, the supporting legs are configured on the triangular metallic bracket such that one leg is supported on a corresponding threaded boss configured on the air-intake pipe side of the intermediate connections and the remaining three supporting legs are supported on the other three corresponding threaded bosses disposed on the distribution tube side of the intermediate connections.

Typically, the triangular metallic bracket weighs approximately 10 to 20% of the weight of the plastic air-intake manifold.

Typically, the metallic bracket is configured circular, oval, rectangular, square or in any other shape and with a plurality of straight, curved or profiled stiffening arms of any size and cross-section.

Typically, the metallic bracket is adapted to the dimensions of the weakest portion of the plastic air-intake manifold of different models.

Typically, the metallic bracket is made of steel, e.g. mild steel.

Typically, the metallic bracket is made of cast aluminum.

Typically, the supporting legs are configured integral to the metallic bracket, for example by welding or casting.

Typically, the bosses are configured integral to the metallic bracket, for example by welding or casting and subsequently internally threaded.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, which include:

Figure 1 shows a typical structure of an air-intake manifold for an automotive internal combustion engine illustrating the weak portion thereof requiring stiffening for reduce engine surface vibrations and noise levels.

Figure 1a shows a metallic beam-structure in accordance with the invention for stiffening the weak portion of the air-intake manifold shown in Figure 1 for reducing the engine surface vibrations and noise levels.

Figure 2 shows a schematic layout of the metallic beam-structure of Figure 1a mounted on the weak portion of the air-intake manifold shown in Figure 1 for stiffening thereof.

Figure 3 shows one of the graphs illustrating the driving point mobility taken at one location of the intake manifold structure strengthened by the metallic beam –structure (Fig. 1a) in accordance with the present invention.

Figure 4 shows another graph illustrating the driving point mobility taken at a different location of the intake manifold structure strengthened by the metallic beam –structure (Fig. 1a) in accordance with the present invention.

Figure 5 shows still another graph illustrating the driving point mobility taken at one more location of the intake manifold structure strengthened by the metallic beam –structure (Fig. 1a) in accordance with the present invention.

Figure 6 shows yet another graph illustrating the driving point mobility taken at another location of the intake manifold structure strengthened by the metallic beam –structure (Fig. 1a) in accordance with the present invention.

Figure 7 shows a graph of vibration point mobility improvement by using the metallic beam-structure in accordance with the present invention.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, different embodiments of the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1 shows a typical structure of an air-intake manifold 10 with an air-intake side 6 and a plurality of corresponding air distribution side 8 for supplying air to the intake ports in the cylinder head of an automotive internal combustion engine (not shown). The figure illustrates an air intake pipe 10 configured with a plurality of intermediate connections requiring a stiffener to reduce engine surface vibrations and noise levels. These intermediate connections 12 are connected to the corresponding plurality of profiled air-distribution tubes 28 to be attached to the respective inlet ports at the respective points 8 of the cylinder head in a direct injection engine. The intermediate connections 12 are configured with a plurality of internally threaded bosses 30 disposed perpendicular to it and extend towards the top-cover of the air-intake manifold (not shown).

Figure 1a shows a profiled metallic structure 20 configured as a stiffener in accordance with the invention for stiffening the weak portion 12 shown in Fig.1. The metallic structure 12 consists of, e.g. a triangular bracket 20 provided with four supporting legs 24 having through holes for bolting it on the respective threaded bosses configured on the weak intermediate connections 12 located around the top-cover of the of the air-intake manifold 10 (Figure 2).

Figure 2 shows a schematic layout of a triangular metallic bracket 20 of Figure 1a mounted on weak intermediate connections 12 of the air-intake manifold 10 shown in Figure 1 for stiffening the area around the top-cover attachment location thereof. A plurality of straight supporting leg 24 (four here) of the triangular metallic bracket 20 are attached substantially perpendicular to the intermediate connections 12 and extend away from the top cover attachment location on the air-intake manifold 10. These supporting legs 24 are disposed such that one leg 24 is supported on a respective threaded boss 30 configured on the air-intake pipe 6 side of the intermediate connections 12 and the remaining three supporting legs 24 are supported on the other three respective threaded bosses 30 disposed on the distribution tubes 28 side of the intermediate connections 12. The triangular bracket 20 is bolted by means of bolts 26 on the respective threaded boss configured on the intermediate connections 12 for the purpose of stiffening thereof. The weight of the original plastic air-intake manifold 10 is about 2 kg and by addition of this triangular bracket 20, it weighs about 2.3 kg, which is very less in proportion to the benefits accrued by incorporating this metallic bracket 20 on the plastic air-intake manifold 10. This is also economical in comparison to the local stiffening, if provided on the air-intake manifold 10, which would also have serious manufacturing constraints because different models would require different local stiffening designs, whereas adapting this simple metallic bracket 20 to different air-intake manifolds would be much easier and more cost-effective. The size of the metallic bracket 20 in this embodiment is 200 x 150 x 50 mm3. However, it can be made of any size, profile and cross-section depending on the space available and stiffness required for different models of vehicles.

According to the paragraph 4.3 of the Research Report BVAL37-021228 dated 05.11.2002, entitled “Mechanical Mobility Technique” by Pertti Hynna available online (Link), the driving-point mobility or direct (mechanical) mobility Yii is a complex ratio of velocity and force taken at the same point in a mechanical system during simple harmonic motion [ISO 2041, 1990, Vibration and shock – Vocabulary – Geneva: International Organization for Standardization, 23 pp.]. Here, point means both a location and a direction. Sometimes the term co-ordinate is used instead of the point.

Accordingly, driving-point mobility tests were carried out at four locations of the air-intake manifold 10 for assessing the performance of this metallic beam-structure 20 as against the original air-intake manifold 10 without the metallic beam-structure 20 in accordance of the present invention. The results obtained are illustrated in Figures 3 to 6 and described in details subsequently.

Figure 3 shows one of the graphs illustrating the driving point mobility taken at one of the locations of the intake manifold structure on the top-cover attachment to strengthen it by the metallic beam–structure in accordance with the present invention as discussed above in respect of the Figs. 1, 1a and 2). Here, the solid-line represents the behavior with the original air-intake manifold 10 shown in Figure 1 and dashed-line represents the behavior with the metallic beam-structure 20 (Fig. 1a) fixed on the original AIM 10 (Fig. 2).

The graph shows Frequency on X-axis and “Velocity / Force” ratio on LHS and “Amplitude” on the RHS on the Y-axis. The graph also shows inset the comparative values for “Maximum Amplitude”, “Root Sum Square” (RSS) and “Root-Mean Square” (RMS) for the Original as well as stiffened air-intake manifold 10 at this location, which are reduced by 37.34%, 27.51% and 27.52% respectively. Therefore, the air-intake manifold stiffened according to the present invention shows a substantial improvement in the performance of the original air-intake manifold, which is very cost-effective and easy to implement in different models of air-intake manifolds.

Figure 4 shows another similar graph illustrating the driving point mobility taken at a different location of the intake manifold structure strengthened by the metallic beam –structure (Fig. 1a) in accordance with the invention. Here, the values of Maximum Amplitude, RSS and RMS for the beam-structure stiffened air-intake manifold are reduced by 49.16%, 17.13% and 17.14% respectively.

Figure 5 shows still another graph illustrating the driving point mobility taken at one more location of the intake manifold structure strengthened by the metallic beam –structure (Fig. 1a) in accordance with the present invention. Here again, the values of Maximum Amplitude, RSS and RMS for the beam-structure stiffened air-intake manifold are reduced by 41.40%, 30.96% and 30.91% respectively.

Figure 6 shows yet another graph illustrating the driving point mobility taken at another location of the intake manifold structure strengthened by the metallic beam –structure (Fig. 1a) in accordance with the present invention. Even at this location, the values of Maximum Amplitude, RSS and RMS for the beam-structure stiffened air-intake manifold are reduced by 43.16%, 18.19% and 17.90% respectively.

Figure 7 shows a graph of vibration point mobility improvement by using the metallic beam-structure in accordance with the present invention, wherein Frequency is shown on X-axis and decibel “dB” values in (m/s)/N (dB reference 1 m/s) on LHS of the Y-axis and “Amplitude” on RHS on the Y-axis. The upper (red) line represents the values for the original air-intake manifold of plastic and the lower (green) line represents the values for the same manifold, however stiffened by attaching a metallic beam-structure in accordance with the present invention. The arrow pointing downwards shows the substantial reduction in decibel (dB) values and amplitude of vibrations due to this important intervention in the air-intake manifold.

Working of the Invention:

Since the modal characteristics of any component govern its vibration behavior, which in turn depend on its shape, mass and stiffness of the structure. The addition of steel beam structure has increased the stiffness of the plastic based Air Intake Manifold. This has reduced modal density as well as the modal displacements, thereby reducing the vibration response thereof.

Technical advantages and economic significance

The steel beam-structure for stiffening of plastic intake manifold for reducing the engine surface vibrations and noise levels configured in accordance with the present invention has the following advantages:

• Significant improvement achieved in the vibration response.

• Reduced manufacturing cost, so higher benefit to cost ratio achieved.

• Desirable NVH levels for AIM achieved.

• Steel beam structure can be implemented even at a later stage of designing.

• No change required in the basic structural design of the AIM.

• AIM can be easily adapted to different desirable NVH levels or various engine models just by changing the stiffener structure, e.g. size and cross-section.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention. Although, only the preferred embodiments have been described herein, the skilled person in the art would readily recognize to apply these embodiments with any modification possible within the spirit and scope of the present invention as described in this specification.

Therefore, innumerable changes, variations, modifications, alterations may be made and/or integrations in terms of materials and method used may be devised to configure, manufacture and assemble various constituents, components, subassemblies and assemblies according to their size, shapes, orientations and interrelationships. The description provided herein is purely by way of example and illustration.

The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention.

The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.

While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.