JP2009167899A - Air intake structure of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air intake structure of an internal combustion engine, reducing variations of the numbers of revolutions between cylinders in a resonance synchronization engine even when a surge tank capacity is low. <P>SOLUTION: The air intake structure of the internal combustion engine comprises: a surge tank having an intake pipe opening part; and a plurality of manifold opening parts, and a plurality of manifolds connected downstream of the surge tank and is characterized in that the manifold longest in distance from the intake pipe opening part to the manifold opening part is shorter than the manifold shortest in the distance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an intake structure for an internal combustion engine, and more particularly to an intake structure for an internal combustion engine that can be suitably used for an internal combustion engine having a small-capacity surge tank.

  In an internal combustion engine having a plurality of cylinders, the intake sound characteristics can be improved as the intervals between the intake passages for introducing intake air to the cylinders are equal. For example, the internal combustion engine shown in Patent Document 1 includes a surge tank and a plurality of manifolds of equal length. The distance of the intake passage from the intake pipe opening to each manifold opening of the surge tank (hereinafter also referred to as “intake pipe length”) is equalized. As a result, the intake sound characteristic can be improved.

JP 2005-113853 A JP 2005-133617 A JP-A-9-264213 Japanese Utility Model Publication No. 61-159624

  By the way, an internal combustion engine is required to improve the volume efficiency by reducing the variation in the rotational speed of the resonance-tuned engine between cylinders. This variation can be improved by making the intake pipe lengths equal. In Patent Document 1, since the intake pipe length is made equal, this variation can be improved and the volume efficiency can be improved.

  However, recent automobiles are required to save space in the engine room. That is, it is required to make the contents of the internal structure of the internal combustion engine including the surge tank compact. In such a situation, the conventional technology based on a sufficient surge tank capacity cannot always realize the reduction of the variation.

  The present invention has been made to solve the above-described problem, and provides an intake structure for an internal combustion engine that can reduce variation in the resonance-tuned engine speed between cylinders even if the surge tank volume is reduced. Objective.

In order to achieve the above object, a first invention is an intake structure for an internal combustion engine,
A surge tank comprising an intake pipe opening and a plurality of manifold openings;
A plurality of manifolds connected downstream of the surge tank;
The manifold having the longest distance from the intake pipe opening to the manifold opening is characterized by being shorter than the manifold having the shortest distance.

  According to a second aspect, in the first aspect, the manifold connecting the intake port opening and the surge tank is shorter as the distance is longer.

The third invention is the first or second invention, wherein the surge tank includes the intake pipe opening at one end in a longitudinal direction,
The manifolds are arranged in order along the longitudinal direction, and are designed to be shorter as they move away from the one end.

Moreover, 4th invention is set in 3rd invention,
The surge tank includes a variable intake valve that divides an internal space into two in a longitudinal direction.

  According to the first invention, even if the surge tank volume is reduced, it is possible to improve the variation in the resonance tuning engine speed among a plurality of cylinders. Therefore, it is possible to provide an intake structure for an internal combustion engine that simultaneously improves the problem of engine mountability and the problem of volume efficiency.

  According to the second aspect of the present invention, it is possible to improve the dispersion of the resonance-tuned engine speed among a plurality of cylinders regardless of the arrangement of the intake pipe opening and the manifold opening of the surge tank. Therefore, it is possible to provide an intake structure for an internal combustion engine that simultaneously improves the problem of the demand for compactness of the entire intake device including the surge tank and the problem of volume efficiency.

  According to the third aspect of the invention, it is possible to improve the variation in the resonance tuning engine speed between the cylinders arranged in order along the longitudinal direction of the surge tank. Therefore, it is possible to provide an intake structure for an internal combustion engine that can simultaneously improve the problem of realistic engine mountability and the problem of volumetric efficiency.

  According to the fourth aspect of the invention, even when a variable intake valve is installed in the surge tank, it is possible to improve the variation in the resonance-tuned engine speed among a plurality of cylinders.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 shows a cross-sectional view of an intake structure for an internal combustion engine in the first embodiment. FIG. 1 is a cross-sectional view of an in-line four-cylinder intake structure. The vehicle 10 in FIG. 1 is equipped with an internal combustion engine. The internal combustion engine includes a surge tank 11. An air cleaner 12 is installed upstream of the surge tank 11, and these communicate with each other via an intake pipe. The air cleaner 12 may be an intercooler. A throttle body 13 having a throttle valve is installed between the surge tank 11 and the air cleaner 12. An air duct 14 is installed upstream of the air cleaner 12.

  The surge tank 11 includes an intake pipe opening 15 and manifold openings 18a, 18b, 18c, and 18d. The surge tank 11 is connected to intake port openings 19a, 19b, 19c, 19d provided in the cylinder head 20 via manifolds 17a, 17b, 17c, 17d. Intake gas (intake air) flows from the air duct 14 into the air cleaner 12, the throttle body 13, and the surge tank 11 in this order, and passes through the manifolds 17a, 17b, 17c, and 17d to # 1 and # 2 in the cylinder head 20. , # 3, # 4 flows into each cylinder.

  In FIG. 1, the manifold 17a having the longest distance (intake pipe length) of each intake passage from the intake pipe opening 15 to the manifold openings 18a, 18b, 18c, and 18d is changed to the manifold 17d having the shortest intake pipe length. Shorter than that. The manifold 17a having a long intake pipe length is shorter than the manifold 17b having a relatively short intake pipe length. The manifold 17b is shorter than the manifold 17c having a relatively short intake pipe length. Similarly, the manifold 17c is shorter than the manifold 17d.

  Generally, providing a surge tank has an effect of increasing the volume of intake air. For this reason, the influence which arises between each cylinder, for example, the influence of the resonance tuning engine speed between each cylinder, can be reduced. However, recent automobiles are required to save space in the engine room. Therefore, the surge tank 11 itself is also required to be compact. If the surge tank 11 is made compact, that is, if the volume of the surge tank 11 is reduced, the surge tank 11 functions like an intake pipe. Then, the influence of the intake pulsation from the air cleaner 12 cannot be ignored. Specifically, intake pulsation from the air cleaner 12 is generated by opening and closing the throttle valve, which affects the resonance-tuned engine speed of each cylinder.

  This effect can be explained by the following principle. By opening the throttle valve of the throttle body 13, pulsation occurs in the intake air from the air cleaner 12. When the capacity of the surge tank 11 is large, the influence of this intake pulsation on each cylinder is small. However, when the capacity of the surge tank 11 decreases, the surge tank itself functions as a single intake pipe. The low-frequency intake pulsation in the intake pulsation affects the resonance tuning engine speed of each cylinder. This effect increases as the intake pipe length increases. As a result, the resonance tuning engine speed decreases as the length of the intake pipe increases.

  Therefore, in the first embodiment, paying attention to the length of the manifold, the variation in the resonance tuning engine speed of each cylinder is reduced. Specifically, the manifold 17a having the longest intake pipe length is made shorter than the manifold 17d having the shortest intake pipe length. This reduces the variation in resonance tuning engine speed between these two manifolds.

  Further, the length of the manifold may be shortened as the intake pipe length is longer. By doing so, it is possible to reduce variations in the resonance tuning engine speed of each cylinder. As described above, in FIG. 1, the manifold 17a having a long intake pipe length is shorter than the manifold 17b having a relatively short intake pipe length. The manifold 17b is shorter than the manifold 17c. Similarly, the manifold 17c is shorter than the manifold 17d. That is, the lengths of the manifolds 17a, 17b, 17c, and 17d may be changed according to the arrangement of the intake pipe opening 11 and the manifold openings 18a, 18b, 18c, and 18d of the surge tank.

  Further, when the intake pipe opening 15 is provided at one end in the longitudinal direction of the surge tank 11, the manifolds 17 a, 17 b, 17 c, and 17 d are arranged in order along the longitudinal direction of the surge tank 11. At the same time, these manifolds are designed to be short enough away from the intake pipe opening 15.

  For comparison with the first embodiment, FIG. 2 shows a form in which the manifolds 17a, 17b, 17c, and 17d have the same length. In FIG. 2, the intake pipe length from the intake pipe opening 15 to the manifold openings 18a, 18b, 18c, and 18d is the longest in the manifold 17a and is shorter in the order of 17b, 17c, and 17d.

  FIG. 3 is a diagram showing the distance of each intake passage in FIG. Here, attention is focused on cylinders # 1 and # 4 corresponding to the manifolds 17a and 17d, respectively. As shown in FIG. 3, the relationship between the intake pipe lengths in these two cylinders is # 1> # 4. The lengths of the manifold 17a and the manifold 17d are equal. By opening the throttle valve of the throttle body 13, pulsation occurs in the intake air from the air cleaner 12. When the capacity of the surge tank 11 is large, the influence of the intake pulsation on these two cylinders is small. However, when the capacity of the surge tank 11 decreases, the low-frequency intake pulsation flowing from the air cleaner 12 affects the # 1 cylinder having a long intake pipe length. Then, as the intake pipe length is longer, the # 1 cylinder has a lower resonance tuning engine speed. In FIG. 3, 32 and 33 visually indicate the influence of the intake pulsation corresponding to # 1 and # 4, respectively.

[Effect of Embodiment 1]
FIG. 4 shows the relationship between the number of cylinders and the resonance-tuned engine speed (resonance frequency) of each cylinder. FIG. 4A shows a relationship in an intake structure in which all manifolds have the same length. On the other hand, FIG. 4B shows the relationship in the first embodiment. In addition, 1-4 of the horizontal axis of Fig.4 (a), (b) has shown each cylinder of # 1- # 4, respectively. The resonance frequency is a substitute value of the resonance tuning engine speed, and can be measured by an acoustic vibration test of each manifold.

  FIG. 4A shows that the resonance frequency of each cylinder decreases as the intake pipe length increases. On the other hand, in Embodiment 1, as shown in FIG.4 (b), it turns out that the dispersion | variation in the resonant frequency of each cylinder is reduced. That is, in the first embodiment, variation in the resonance tuning engine speed of each cylinder is reduced.

  FIG. 5 shows the relationship between the rotation angle of the crankshaft and the pressure in each cylinder. FIG. 5A shows the relationship in the intake structure in which all the manifolds have the same length. On the other hand, FIG. 5B shows the relationship in the first embodiment. In addition, the horizontal axis | shaft of Fig.5 (a), (b) has shown the crank angle at the time of 4 cycles. The pressure in each cylinder can be obtained by measuring the pressure (negative pressure) of each manifold.

  In FIG. 5A, it can be seen that the pressure waveform is not uniform between the cylinders. On the other hand, in Embodiment 1, they are aligned as shown in FIG. This result shows that the variation in the resonance tuning engine speed between the cylinders is reduced by the first embodiment.

  The effect by Embodiment 1 is shown in FIGS. First, FIG. 6 shows the relationship between engine speed and volumetric efficiency. According to the first embodiment, the variation in the resonance-tuned engine speed between the cylinders is reduced. As a result, the volumetric efficiency of the internal combustion engine is improved. Next, FIG. 7 shows the relationship between the engine speed and the corrected shaft torque. According to the first embodiment, the torque is improved. The corrected shaft torque is obtained by adding a correction coefficient to the calculated shaft torque. FIG. 8 shows the relationship between the engine speed and the corrected shaft output. Like the corrected shaft torque, the corrected shaft output can be improved. From these effects, it was shown that engine performance improved.

  By taking the first embodiment, in addition to the above effects, the surge tank can be reduced in shape. Specifically, it is shown in FIG. In FIG. 9, the shape of the surge tank 91 having the same length of all the manifolds is indicated by a dotted line. On the other hand, the shape of surge tank 92 obtained by taking Embodiment 1 is shown by a solid line. That is, the entire intake device including the surge tank can be made compact.

  Further, by taking the first embodiment, a variable intake valve can be provided in the surge tank. If space saving of the surge tank can be achieved, a variable intake valve can be installed in the surge tank to further improve volumetric efficiency. FIG. 10 is a view in which a variable intake valve 101 is provided in the surge tank.

  In the first embodiment described above, the intake structure of the in-line four-cylinder internal combustion engine is adopted. However, it is possible to adopt a V-type 8-cylinder or V-type 6-cylinder intake structure. Further, in this case, an embodiment in which a variable intake valve is provided in the surge tank can be employed.

Embodiment 2. FIG.
[Configuration of Embodiment 2]
In the following description, a characteristic configuration of the present embodiment will be described, and description of other points similar to those of the first embodiment will be omitted.
A second embodiment of the present invention will be described with reference to FIGS. FIG. 11 is a view of the intake structure of the internal combustion engine in the second embodiment as viewed from above. FIG. 11 is a view of the V-type 6-cylinder intake structure as viewed from above. The intake structure in FIG. 11 includes a surge tank 111. An air cleaner 112 is installed upstream of the surge tank 111, and these are communicated via an intake pipe. The air cleaner 112 may be an intercooler. The surge tank 111 includes manifolds 113a, 113b, 113c, 113d, 113e, and 113f. These manifolds are manifolds corresponding to # 1 to # 6, respectively. Further, these manifolds communicate with a cylinder head (not shown) in the downward direction of the drawing.

  In FIG. 11, the manifold 113a having the longest intake pipe length is shorter than other manifolds. The structure of the surge tank 111 in this case is such that the manifold opening 114a is closer to the # 1 direction. For comparison, FIG. 11 shows the shape of the surge tank 115 when all the manifolds are equal to each other with a dotted line.

  FIG. 12 is shown for comparison with the second embodiment. FIG. 12 is a side view when an intake structure having the same length of the manifolds 113a, 113b, 113c, 113d, 113e, and 113f is mounted on the vehicle. The arrow in FIG. 12 indicates the front direction of the vehicle. And the engine hood 121 of FIG. 12 inclines below toward the vehicle front.

  FIG. 13 is a view of the intake structure of FIG. 12 as viewed obliquely from above. As shown in the description of FIG. 12, the engine hood 121 is inclined downward toward the front of the vehicle. That is, the space of the surge tank height decreases toward the front of the vehicle. Therefore, the surge tank 115 of FIG. 13 has a structure that is inclined downward toward the front of the vehicle.

  FIG. 14 shows a view of the intake structure of FIG. 12 as viewed from above. The length of the manifold of each cylinder in FIG. 14 is equal. The length of the intake pipe is the longest in the manifold 113a and decreases in the order of 113b, 113c, 113d, 113e, and 113f. Since the surge tank 115 is inclined downward toward the front of the vehicle, the manifold 113b has a shape that fits into the surge tank 115. As shown in FIG. 14, the manifold opening 141b corresponding to the manifold 113b has a shape that is recessed into the surge tank 115 from the original position. On the other hand, the manifold opening 141a is located further downward in the vehicle front direction than the manifold opening 141b.

  When the volume of the surge tank 115 is reduced and the surge tank shape and the manifold are arranged as described above, low-frequency intake pulsation flowing from the air cleaner 112 has an effect. Specifically, the vicinity 142 upstream of the manifold opening 141a functions like an intake pipe. The low-frequency intake pulsation in the intake pulsation affects the resonance tuning engine speed of each cylinder. As a result, the resonance-tuned engine speed of the # 1 cylinder having the longest intake pipe length is reduced as compared with other cylinders.

  Therefore, in the second embodiment, only the manifold 113a having the longest intake pipe length is made shorter than the other manifolds. By doing so, the resonance tuning engine speed of the # 1 cylinder can be made equal to the resonance tuning engine speed of the other cylinders.

[Effect of Embodiment 2]
FIG. 15 shows the relationship between the number of cylinders and the resonance-tuned engine speed (resonance frequency) of each cylinder. FIG. 15A shows a relationship in an intake structure in which all manifolds have the same length. On the other hand, FIG. 15B shows the relationship in the second embodiment. In addition, 1-6 of the horizontal axis of Fig.15 (a), (b) has shown each cylinder of # 1- # 6, respectively.

  FIG. 15 (a) shows that the resonance-tuned engine speed of the # 1 cylinder is lower than that of the other cylinders. On the other hand, in the second embodiment, as shown in FIG. 15 (b), the resonance-tuned engine speed of the # 1 cylinder is increased, and the variation from the resonance-tuned engine speed of the other cylinders is reduced. As a result, the volume efficiency of the internal combustion engine is improved and the torque and output are improved, so that the engine performance is improved.

Embodiment 3 FIG.
[Configuration of Embodiment 3]
In the following description, a characteristic configuration of the present embodiment will be described, and description of other points similar to those of the first and second embodiments will be omitted.
A third embodiment of the present invention will be described with reference to FIGS. FIG. 16 is a view of the intake structure of the internal combustion engine in the third embodiment as viewed from above. FIG. 16 is a view of the intake structure of the V-type 6 cylinder with the variable intake valve 160 as viewed from above. Here, the variable intake valve 160 opens and closes based on instructions from an engine control computer (not shown). Thereby, the variable intake valve 160 divides the internal space of the surge tank 161 into two.

  An air cleaner 162 is installed upstream of the surge tank 161, and these are communicated with each other via an intake pipe. The air cleaner 162 may be an intercooler. The surge tank 161 includes manifolds 163a, 163b, 163c, 163d, 163e, and 163f. These manifolds are manifolds corresponding to # 1 to # 6, respectively. Further, these manifolds communicate with a cylinder head (not shown) in the downward direction of the drawing.

  In FIG. 16, manifolds 163a and 163b are shorter than other manifolds. Further, the manifold 163a having the longest intake pipe length is shorter than the manifold 163b. The structure of the surge tank 161 in this case is such that the manifold openings 164a and 164b are closer to the # 1 and # 2 directions, respectively. For comparison, FIG. 16 shows the shape of the surge tank 165 when all the manifolds are equal to each other with a broken line.

  FIG. 17 is shown for comparison with the third embodiment. FIG. 17 is a side view when an intake structure having the same length of the manifolds 163a, 163b, 163c, 163d, 163e, and 163f is mounted on the vehicle. The arrow in FIG. 17 indicates the front direction of the vehicle. And the engine hood 171 of FIG. 17 inclines below toward the vehicle front.

  18 is a view of the intake structure of FIG. 17 as viewed obliquely from above. As described above, the engine hood 171 is inclined downward toward the front of the vehicle. That is, the space of the surge tank height decreases toward the front of the vehicle. Therefore, the surge tank 165 has a structure that is inclined downward toward the front of the vehicle.

  FIG. 19 shows a view of the intake structure of FIG. 17 as viewed from above. The length of the manifold of each cylinder in FIG. 19 is equal. In addition, the length of the intake pipe is the longest in the manifold 163a, and decreases in the order of 163b, 163c, 163d, 163e, and 163f. As described above, the surge tank 165 is inclined downward in the vehicle front direction. Here, when the variable intake valve 160 is installed in the surge tank 165, the surge tank 165 has a structure as shown in FIG.

  FIG. 20 shows a view of the intake structure of FIG. 17 as viewed from above. In the structure of the surge tank as shown in FIG. 19, when the variable intake valve 160 is opened, low-frequency intake pulsation from the air cleaner 162 has an effect. Specifically, when the variable intake valve 160 is opened, the vicinity 202a upstream of the manifold opening 201a and the vicinity 202b upstream of the manifold opening 201b function as an intake pipe. The low-frequency intake pulsation in the intake pulsation affects the resonance tuning engine speed of each cylinder. Then, when the variable intake valve 160 is opened, the resonance-tuned engine speeds of the # 1 and # 2 cylinders with long intake pipe lengths are lower than the resonance-tuned engine speeds of the other cylinders.

  Therefore, in the third embodiment, the manifolds 163a and 163b are made shorter than the other manifolds. The manifold 163a is shorter than the manifold 163b. By doing so, the resonance-tuned engine speeds of the cylinders of # 1 and # 2 can be aligned with those of the other cylinders.

[Effect of Embodiment 3]
FIG. 21 shows the relationship between the number of cylinders and the resonance-tuned engine speed (resonance frequency) of each cylinder. FIG. 21A shows a relationship in an intake structure in which all manifolds have the same length. On the other hand, FIG. 21B shows the relationship in the third embodiment. In addition, 1-6 of the horizontal axis of FIG. 21 (a), (b) has shown each cylinder of # 1- # 6, respectively.

  From FIG. 21 (a), it can be seen that the resonance-tuned engine speeds of the # 1 and # 2 cylinders are lower than those of the other cylinders. On the other hand, in the third embodiment, as shown in FIG. 21 (b), the resonance-tuned engine speeds of the # 1 and # 2 cylinders are increased, and variations from the resonance-tuned engine speeds of the other cylinders are reduced. . As a result, the volume efficiency of the internal combustion engine is improved and the torque and output are improved, so that the engine performance is improved.

It is sectional drawing of the intake structure of the internal combustion engine in Embodiment 1 of this invention. 2 is a cross-sectional view of an intake structure for an internal combustion engine for comparison with the first embodiment. FIG. It is a figure which shows the distance of each intake passage in FIG. It is a figure which shows the relationship between the number of cylinders in Embodiment 1 of this invention, and the resonant frequency of each cylinder. It is a figure which shows the relationship between the rotation angle of a crankshaft, and the pressure in each cylinder in Embodiment 1 of this invention. It is a figure which shows the relationship between an engine speed and volumetric efficiency in Embodiment 1 of this invention. It is a figure which shows the relationship between an engine speed and corrected shaft torque in Embodiment 1 of this invention. It is a figure which shows the relationship between an engine speed and corrected shaft output in Embodiment 1 of this invention. It is a figure which shows the effect which can make the shape of a surge tank small in Embodiment 1 of this invention. It is a figure which shows the effect which can provide a variable intake valve in a surge tank in Embodiment 1 of this invention. FIG. 6 is a view of an intake structure for an internal combustion engine according to a second embodiment as viewed from above. 6 is a cross-sectional view of an intake structure of an internal combustion engine for comparison with Embodiment 2. FIG. It is the figure which looked at the intake structure of FIG. 12 from diagonally upward. It is the figure which looked at the intake structure of FIG. 12 from upper direction. It is a figure which shows the relationship between the number of cylinders in Embodiment 2 of this invention, and the resonant frequency of each cylinder. FIG. 6 is a view of an intake structure for an internal combustion engine according to Embodiment 3 as viewed from above. FIG. 6 is a cross-sectional view of an intake structure for an internal combustion engine for comparison with a third embodiment. It is the figure which looked at the intake structure of FIG. 17 from diagonally upward. It is the figure which looked at the air intake structure of Drawing 17 from the upper part. It is the figure which looked at the air intake structure of Drawing 17 from the upper part. It is a figure which shows the relationship between the number of cylinders and the resonant frequency of each cylinder in Embodiment 3 of this invention.

Explanation of symbols

11 Surge tank 15 Intake pipe opening 17a, 17b, 17c, 17d Manifold 18a, 18b, 18c, 18d Manifold opening 19a, 19b, 19c, 19d Inlet port opening

Claims (4)

A surge tank comprising an intake pipe opening and a plurality of manifold openings;
A plurality of manifolds connected downstream of the surge tank;
An intake structure for an internal combustion engine, wherein the manifold having the longest distance from the intake pipe opening to the manifold opening is shorter than the manifold having the shortest distance.   The intake structure for an internal combustion engine according to claim 1, wherein the manifold connecting the intake port opening and the surge tank is shorter as the distance is longer. The surge tank includes the intake pipe opening at one end in the longitudinal direction,
3. The intake structure for an internal combustion engine according to claim 1, wherein the manifold is arranged in order along the longitudinal direction, and is designed to be shorter as it is farther from the one end. 4.   The intake structure for an internal combustion engine according to claim 3, wherein the surge tank includes a variable intake valve that divides the internal space into two in the longitudinal direction.

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