please someone explain to me in as much detail as possible how the expansion-type intake manifold works thank

do your own auto shop homework

Did a quick search & found this very good answer, hope it helps.

The air intake manifold on the new 911 GT2 employs a totally new principle unlike anything ever featured on exiting induction systems. Our ‘expansion’ intake manifolds is a radical new development that is the polar opposite of the resonance principle used on conventional turbocharged engines.

A resonance manifold increases engine output by forcing additional air into the combustion chambers. To do this, the manifold is designed in such a way that the air – which vibrates due to the action of the valves – is in a compression phase as it passes through the inlet ports. Unfortunately, compression not only increases air volume, it also increases air temperature. The result is poorer ignition.

Our new expansion manifold simply turns that principle around. The internal geometry is radically different from that on a resonance intake system. Key modifications include a longer distributor pipe, with a smaller diameter & shorter intake ports.

As a s result, the air is in the expansion phase as it enters the combustion chambers. Since expansion always cools, the air/fuel temperature is lower & ignition is significantly improved – thereby increasing performance. Of course, the amount of air that enters the engine under expansion is less than it would be under compression.

To compensate for this, we’ve simply increased the boost pressure from the turbos by approximately 2.9psi. The resulting increase in temperature – again through compression – is immediately offset by the up rated intercoolers.

Instead of hot compressed air entering the combustion chambers, we now have cooler air generating more power & torque. The result: a major improvement in engine efficiency & therefore lower fuel consumption even under heavy loads & high rpm.

A simple solution, but then that’s often the way when u take a new approach to old ideas.

1. Field of the Invention

The present invention relates to an intake muffler duct for motor vehicles which guide air to the motor vehicle engine as well as reduce the intake noise.

2. Description of the Prior Art

The intake duct which supplies air to the engine of a motor vehicle is equipped with an intake muffler in order to reduce the intake noise, & with regard to such intake mufflers there r expansion type mufflers, Helmholtz type mufflers, side branch type mufflers, etc. Since it is difficult to reduce the intake noise in all frequency regions using a single intake muffler, multiple intake mufflers each of which reduces the intake noise in a specific frequency range r combined so as to reduce the intake noise over a wide frequency range (see for example Japanese Patent Application Laid-open No. 4-318269).

However, since an engine & a large number of accessories r placed in the motor vehicle engine compartment, it is difficult to ensure that there is space to install multiple intake mufflers. In addition, if multiple intake mufflers r installed independently, the number of components, the number of processing steps & the number of assembly steps increase, resulting in an increase in cost.

SUMMARY OF THE INVENTION

The present invention has been conducted in view of the above-mentioned circumstances, & it is an objective of the present invention to provide a motor vehicle intake muffler duct which has a compact structure with a small number of components & can effectively reduce intake noise.

In accordance with a first feature of the present invention in order to achieve the above-mentioned objective, a motor vehicle intake muffler duct which introduces air to the engine of the motor vehicle & reduces the intake noise is characterized in that it is formed by integrally bonding a flattened upper duct & a flattened lower duct with a board or plate-shaped separator interposed between them. An airway whose ends r communicated with an air inlet & an air outlet, is formed between the upper duct & the separator, & a multiple number of muffler chambers which r separated from each other by partitions, r formed between the lower duct & the separator. The airway & the muffler chambers r communicated with each other through vent holes which r formed in the separator.

In accordance with the above-mentioned arrangement, since the airway is formed between the upper duct & the separator, the multiple number of muffler chambers r formed between the lower duct & the separator & the airway & the multiple number of muffler chambers r communicated with each other through the vent holes which r formed in the separator, not only can an intake muffler duct integrally comprising an airway & multiple muffler chambers be formed from only the three components of the upper duct, lower duct & separator, but intake noise can also be reduced effectively. In addition, the entire intake muffler duct has a flattened shape & therefore it can be compactly stored in a small space inside motor vehicle engine compartment. Furthermore, the partitions which separate the multiple muffler chambers function as reinforcing ribs thus enhancing the rigidity of the lower duct.

In accordance with a second feature of the present invention, the motor vehicle intake muffler duct is characterized in that multiple airways r formed in parallel by partitions which r formed in the upper duct.

In accordance with the above-mentioned arrangement, since the multiple airways r formed in parallel by forming the partitions in the upper duct, it becomes easier to tune the muffler characteristics in comparison with the case where there is only one airway. Furthermore, since the partitions which separate the multiple airways function as reinforcing ribs, the rigidity of the upper duct is thus enhanced.

In accordance with a third feature of the present invention, the motor vehicle intake muffler duct is characterized in that a side branch type muffler is formed by introducing one vent hole into one muffler chamber.

In accordance with the above-mentioned arrangement, since one vent hole is introduced into the one muffler chamber, the side branch type muffler is formed & thus a muffler effect can be exhibited.

In accordance with a fourth feature of the present invention, the motor vehicle intake muffler duct is characterized in that an interference type muffler is formed by introducing two vent holes into one muffler chamber.

In accordance with the above-mentioned arrangement, since the two vent holes r introduced into the one muffler chamber, the interference type muffler is formed & thus a muffler effect can be exhibited.

In accordance with a fifth feature of the present invention, the motor vehicle intake muffler duct is characterized in that the periphery of a vent hole is made so as to protrude with a tubular or cylindrical shape.

In accordance with the above-mentioned arrangement, since the periphery of the vent hole is made so as to protrude with a tubular shape, the above-mentioned vent hole functions as a vent tube having a predetermined length & thus the degrees of freedom in setting the muffler characteristics can be increased.

The above-mentioned objectives, other objectives, characteristics & advantages of the present invention will be elucidated by a preferred embodiment described in detail below by reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an entire intake muffler duct according to one embodiment of the present invention.

FIG. 2 is a view in the direction shown by arrow 2 in FIG. 1.

FIG. 3 is a view in the direction shown by arrow 3 in FIG. 1.

FIG. 4 is a cross-sectional view at line 4--4 in FIG. 3.

FIG. 5 is a cross-sectional view at line 5--5 in FIG. 3.

FIG. 6 is a cross-sectional view at line 6--6 in FIG. 3.

FIG. 7 is a perspective view of a disassembled intake muffler duct.

FIG. 8 is a schematic of an intake muffler duct.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is described below by reference to the Embodiment of the present invention shown in the attached drawings.

FIG. 1 to FIG. 8 illustrate one embodiment of the present invention.

As shown in FIG. 1, an intake path which introduces air to an engine mounted in a motor vehicle engine compartment comprises a first intake duct D1 which forms the intake muffler duct of the present invention, a second intake duct D2 which is communicated with the downstream side of the first intake duct D1 & is integrally equipped with a resonator type intake muffler R & a third intake duct D3 which is communicated with the downstream side of the second intake duct D2 via an air cleaner C. The first intake duct D1 has a flattened shape in its vertical direction & by placing this within the engine compartment so as to abut the underside of the bonnet of the motor vehicle, the small space inside the engine compartment can be used effectively.

The structure of the first intake duct D1 is explained in detail below by reference to FIG. 1 to FIG. 7.

The first intake duct D1 is formed from three components, which r an upper duct UD, a lower duct LD & a separator S, all being formed by the injection moulding of a synthetic resin. The upper duct UD is a flattened component having a generally pentagonal outline & an open base & integrally comprises a flat top wall 1, two side wall sheets 2, 2 which hang down from the right & left edges of the top wall 1, two partition sheets 3, 4 which project downwards from the lower surface of the top wall 1, & an air convergence part 5 which extends backwards from the back edges of the top wall 1 & the side walls 2, 2. At the upstream end of the upper duct UD an air inlet 6 is formed having a long horizontal rectangular shape which is directly open to the air. At the downstream end of the upper duct UD the air convergence part 5 changes its cross section from rectangular to semicircular so as to form the upper half of an air outlet 7. Since the two partition sheets 3, 4 also function as reinforcing ribs, the rigidity of the upper duct UD can be enhanced.

The lower duct LD is a flattened component having the same outline shape as that of the above-mentioned upper duct UD & an open top & comprises a flat base wall 8, four side wall sheets 9 which rise from the periphery thereof, multiple partitions 10 which multiply partition tray-shaped space surrounded by the base wall 8 & the side walls 9, an air guide 11 which extends forwards & downwards from the top of the front side wall 9 so as to form the tail of the above-mentioned air inlet 6, & an air convergence part 12 which extends rearward & downwards from the top of the rear side wall 9. The cross section of the rear edge of the air convergence part 12 has a semicircular shape & together with the air convergence part 5 of the upper duct UD forms the above-mentioned outlet 7 whose cross section has a circular shape. Since the partitions 10 function as reinforcing ribs, the rigidity of the lower duct LD can be enhanced.

The separator S is a square-shaped plate or board component in which eight vent holes 131 to 138 r formed, & two lines of locating channels 14, 15 r formed so as to project from the top surface thereof. The separator S is fitted into the top end parts of the four side walls 9 of the lower duct LD & on the top thereof the upper duct UD is further superimposed. The lower duct LD, the separator S & the upper duct UD r integrally bonded by melt bonding the parts thereof which r in contact with each other.

When the upper duct UD & the separator S r joined, the lower ends of the two partitions 3, 4 of the upper duct UD fit into the two locating channels 14, 15 of the separator S so as to form three airways 16, 17, 18 in parallel above the separator S which r separated by the two partitions 3, 4. The upstream end of each of the airways 16, 17, 18 is communicated with the air inlet 6 & the downstream ends thereof r combined inside the upper & lower air convergence parts 5, 12 & then communicated with the air outlet 7. In the embodiment the forward ends of the partitions 3, 4 only reach a position slightly in from the air inlet 6, but these forward ends may be extended to the position of the air inlet 6.

By integrally forming the lower duct LD & the separator S, seven muffler chambers 191 to 197 r formed. The upper & lower surfaces thereof r made from the separator S & the bottom wall 8 & the side walls thereof r made from the side walls 9 & the partitions 10. Among the seven muffler chambers 191 to 197, six muffler chambers 191 to 196 form side branch type mufflers, & each thereof is communicated with the airways 16, 17, 18 via one of the vent holes 131 to 136. That is to say, as is clear from referring also to FIG. 8, the muffler chambers 191 to 193 r communicated with the airway 16 via the vent holes 131 to 133 respectively, the muffler chambers 194, 195 r communicated with the airway 17 via the vent holes 134, 135 respectively & the muffler chamber 196 is communicated with the airway 18 via the vent hole 136. The remaining muffler chamber 197 forms an interference type muffler (a bypass type muffler) & is communicated with the airway 18 via two vent holes 137, 138 which open at the two ends of the chamber.

As is clear from FIG. 4, FIG. 5 & FIG. 7, among those eight vent holes 131 to 138 formed on the separator S three vent holes 131, 132, 134 have short tubular shapes on their peripheries which project downwards.

Next, the action of the embodiment of the present invention having the above-mentioned arrangement is explained.

Air which is taken in by the vacuum suction generated by the operation of the engine is supplied to the engine through the first intake duct D1, the second intake duct D2 & the third intake duct D3. At this stage, the air taken in via the air inlet 6 of the first intake duct D1 splits into the three airways 16, 17, 18 which r formed by the partitions 3, 4 & then converges in the air convergence parts 5, 12 so as to be supplied to the second intake duct D2 via the air outlet 7.

The three airways 16, 17, 18, through which the air taken in into the first intake duct D1 flows, r communicated with six muffler chambers 191 to 196 via six vent holes 131 to 136 respectively, & therefore by these six muffler chambers 191 to 196 functioning as side branch type mufflers the intake noise can be reduced. Since the airway 18 is communicated with both ends of the muffler chamber 197 in the lengthwise direction via the two vent holes 137, 138, the muffler chamber 197 functions as an interference type muffler so as to reduce the intake noise.

In the above-mentioned embodiment, the three airways 16, 17, 18 r formed by the two partitions 3, 4, but it is possible to easily increase or decrease the number of airways 16, 17, 18 simply by changing the number of partitions 3, 4. Moreover, due to the formation of the three airways 16, 17, 18, it becomes easier to carry out tuning of the muffler characteristics in comparison with the case where only one airway is used. Although seven muffler chambers 191 to 197 r used in the embodiment, it is possible to easily increase or decrease the number & the volume of the muffler chambers 191 to 197 simply by changing the layout of the partitions 10.

Furthermore, by changing only the volume or the length of the muffler chambers 191 to 197 or the aperture area or the shape of the vent holes 131 to 138, it is possible to easily & freely carry out tuning of the muffler characteristics of each of muffler chambers 191 to 197. In addition, since tubular shapes having a predetermined length r formed on the peripheries of the apertures of the three vent holes 131, 132, 134, it becomes possible for these vent holes 131, 132, 134 to function as vent tubes for the muffler chambers 191, 192, 194, & the range over which the muffler characteristics can be tuned can be further enlarged.

As hereinbefore described, since the seven muffler chambers 191 to 197 r integrally formed in the first intake duct D1, it is possible to decrease the number of components, the number of processing steps & the number of assembly steps in comparison with the case in which seven muffler chambers 191 to 197 r formed individually. Moreover, since the overall shape of the first intake duct D1 is flattened, by placing it against the lower surface of a bonnet, a small narrow space inside the engine compartment can be used effectively.

In the embodiment three airways 16, 17, 18 r formed, but the number thereof is not limited to three & it can be any number including one. Furthermore, the number & the layout of the muffler chambers 191 to 197 r not limited to those in the embodiment, & they can be changed appropriately.

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments r therefore to be considered in all respects as illustrative & not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, & all changes which come within the meaning & range of equivalency of the claims are, therefore, to be embraced therein.