Air intake apparatus

Abstract

This air intake apparatus includes an air intake apparatus main body including a plurality of pieces bonded to each other along a split plane and an external gas passage formed inside the air intake apparatus main body by bonding the plurality of pieces to each other and including an external gas receiving port that directly receives external gas from a cylinder head and an external gas introduction port that introduces the external gas into a surge tank.

Claims

1. An air intake apparatus comprising: an air intake apparatus main body including a plurality of pieces bonded to each other along a predetermined split plane in a state where a surge tank and an air intake port provided between the surge tank and a cylinder head of an internal combustion engine are split by the split plane, and an external gas passage formed inside the air intake apparatus main body by bonding the plurality of pieces to each other and including an external gas receiving port that directly receives external gas from the cylinder head and an external gas introduction port that introduces the external gas into the surge tank, wherein the air intake port includes a plurality of air intake pipes respectively connected to cylinders of the internal combustion engine, and the external gas receiving port faces the cylinder head and is disposed between outlets of the air intake pipes adjacent to each other, the outlets being connected with the cylinder head.

2. The air intake apparatus according to claim 1, wherein the external gas passage further includes a chamber provided between the external gas receiving port and the external gas introduction port and having a passage sectional area larger than those of the external gas receiving port and the external gas introduction port.

3. The air intake apparatus according to claim 2, wherein in a state where the air intake apparatus main body is mounted on the cylinder head, the external gas introduction port is disposed below the chamber and connected to an upper inner surface of the surge tank.

4. The air intake apparatus according to claim 1, wherein an end of the surge tank on one side in an array direction of the plurality of air intake pipes is connected to a throttle valve, and the external gas introduction port is disposed between the air intake pipes adjacent to each other on a side closer to the throttle valve.

5. The air intake apparatus according to claim 4, wherein the external gas receiving port faces the cylinder head and is disposed between outlets of the air intake pipes adjacent to each other on a side closer to the throttle valve.

6. The air intake apparatus according to claim 1, wherein the external gas is blow-by gas.

7. The air intake apparatus according to claim 1, wherein the air intake port has an arcuate shape that is convex in a direction away from the internal combustion engine, and the external gas passage is disposed on a concave side of the arcuate air intake port and between the air intake port and the surge tank.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 A diagram schematically showing the arrangement of an engine and an air intake apparatus according to a first embodiment of the present invention.

(2) FIG. 2 A perspective view of the air intake apparatus according to the first embodiment of the present invention.

(3) FIG. 3 An exploded perspective view of the air intake apparatus according to the first embodiment of the present invention.

(4) FIG. 4 An enlarged sectional view of a blow-by gas passage in the air intake apparatus according to the first embodiment of the present invention.

(5) FIG. 5 A front view of a middle piece that constitutes the air intake apparatus according to the first embodiment of the present invention.

(6) FIG. 6 A rear view of the middle piece that constitutes the air intake apparatus according to the first embodiment of the present invention.

(7) FIG. 7 An exploded perspective view of an air intake apparatus according to a second embodiment of the present invention.

(8) FIG. 8 An enlarged sectional view of a blow-by gas passage in the air intake apparatus according to the second embodiment of the present invention.

MODES FOR CARRYING OUT THE INVENTION

(9) Embodiments of the present invention are hereinafter described on the basis of the drawings.

First Embodiment

(10) The structure of an air intake apparatus 100 according to a first embodiment of the present invention is now described with reference to FIGS. 1 to 6.

(11) The air intake apparatus 100 according to the first embodiment of the present invention is mounted on an in-line four-cylinder engine 110, as shown in FIG. 1. The air intake apparatus 100 partially constitutes an air intake system that supplies air to the engine 110, and the air intake apparatus 100 includes an air intake apparatus main body 80 including a surge tank 10 and an air intake port 20 disposed downstream of the surge tank 10. In the air intake apparatus 100, intake air (incoming air) that reaches an air intake 12 (see FIG. 2) via an air cleaner 120 and a throttle valve 130 flows into the surge tank 10. Then, the intake air is introduced from the surge tank 10 into a cylinder head 111 of the engine 110 via the air intake port 20.

(12) As shown in FIG. 2, the air intake apparatus main body 80 is made of resin (polyamide resin, for example). Specifically, as shown in FIG. 3, an upper piece 81, a middle piece 82, a lower piece 83, and an EGR gas piece 84 are integrally bonded to each other by vibration welding. Thus, the surge tank 10 and the air intake port 20 are configured. As shown in FIGS. 2 and 3, the air intake port 20 is curved with an arcuate shape that is convex in an arrow Y2 direction away from the engine 110 (see FIG. 4).

(13) The upper piece 81 constitutes the outer peripheral side of the curved air intake port 20 and the inner peripheral side of an EGR gas passage 40 described later. The middle piece 82 constitutes the inner peripheral side of the curved air intake port 20 and the upper half of the surge tank 10. The lower piece 83 constitutes the lower half of the surge tank 10 and a distribution passage portion to the air intake port 20. Therefore, in a state where the surge tank 10 and the air intake port 20 provided between the surge tank 10 and the cylinder head 111 (see FIG. 4) are split in advance by a predetermined split plane (a mating surface A described later), the air intake apparatus main body 80 is formed by bonding the surge tank 10 and the air intake port 20 to each other along this mating surface A.

(14) The surge tank 10 includes a hollow body 11 that extends along a cylinder row (X-axis direction) of the engine 110 (see FIG. 1). Upstream ends of air intake pipes 20a, 20b, 20c, and 20d respectively connected to cylinders of the cylinder head 111 (see FIG. 1) are connected to a bottom portion of the body 11. The air intake port 20 includes the air intake pipes 20a to 20d. The air intake pipes 20a to 20d include outlets 21a to 21d. In the air intake apparatus main body 80, an end 13 of the air intake 12 on one side (X1 side) in the array direction (X-axis direction) of the air intake pipes 20a to 20d in the surge tank 10 is connected to the throttle valve 130 (see FIG. 1).

(15) According to the first embodiment, as shown in FIG. 1, the air intake apparatus 100 includes a blow-by gas passage 50 (an example of an external gas passage). That is, blow-by gas (PCV gas) as external gas is recirculated to the engine 110 through the air intake apparatus 100. The blow-by gas denotes an unburned air-fuel mixture containing hydrocarbons (combustion gas) and blown out from gaps between the inner wall surfaces of cylinders 2 and pistons 1 to a crankcase 3 below the cylinders 2 during driving of the engine 110. In the engine 110, after the blow-by gas is discharged from the crankcase 3 to the outside, the blow-by gas is introduced into the air intake apparatus 100 (surge tank 10) via a PCV valve 5 loaded in the cylinder head 111 in a state where particulate oil mist is separated by an oil separator 4.

(16) (Structure of Blow-by Gas Passage)

(17) The blow-by gas passage 50 is not a hose member or the like as a separate component but formed integrally with the air intake apparatus main body 80. In addition, the blow-by gas passage 50 is configured as a passage (pipeline) that connects the crankcase 3 of the engine 110 to the surge tank 10. Specifically, as shown in FIG. 4, the blow-by gas passage 50 as well as the air intake pipes 20a to 20d is formed by vibration welding in a state where a rib-like and circumferential bonding portion 81a of the upper piece 81 and a rib-like and circumferential bonding portion 82a of the middle piece 82 face each other. Furthermore, the surge tank 10 is formed by vibration welding in a state where a rib-like and circumferential bonding portion 82b of the middle piece 82 and a rib-like and circumferential bonding portion 83a of the lower piece 83 face each other. FIG. 4 showing the sectional structure of the blow-by gas passage 50 corresponds to a cross section taken along the line 150-150 in FIGS. 5 and 6.

(18) The inner wall surface 50a of the blow-by gas passage 50 is formed by the mating surface A (an example of a split plane) between the bonding portion 81a and the bonding portion 82a. That is, the upper piece 81 alone includes an opening 81e (see FIG. 4) that opens in the mating surface A, and the middle piece 82 alone includes an opening 82e (see FIG. 5) that opens in the mating surface A. The opening 81e and the opening 82e have the same sectional shape. The upper piece 81 and the middle piece 82 are circumferentially bonded to each other such that the openings 81e and 82e communicate with each other. Thus, one blow-by gas passage 50 is formed solely in the air intake apparatus main body 80 separately from the four air intake pipes 20a to 20d.

(19) As shown in FIG. 4, the blow-by gas passage 50 includes a receiving port 51 (an example of an external gas receiving port) that directly receives the blow-by gas from the cylinder head 111 and an introduction port 52 (an example of an external gas introduction port) that introduces the blow-by gas into the surge tank 10. The introduction port 52 is connected to the upper inner surface 10a of the surge tank 10. The blow-by gas passage 50 is connected to the cylinder head 111 via the PCV valve 5. The PCV valve 5 is a check valve, and has a function of controlling the discharge amount of the blow-by gas. Furthermore, the PCV valve 5 is opened according to the pressure difference when the pressure on the blow-by gas passage 50 side is lower than the pressure on the crankcase 3 (see FIG. 1) side.

(20) Specifically, one gas passage 7 that extends from the crankcase 3 (see FIG. 1) into a cylinder block 112 and the cylinder head 111 is formed inside the cylinder head 111. The PCV valve 5 is inserted into an exit 7a of the gas passage 7 via a seal member 8a to a predetermined extent. Furthermore, a seal member 8b is fitted into a portion of the PCV valve 5 exposed from the exit 7a. When the air intake apparatus main body 80 is assembled to the cylinder head 111, the PCV valve 5 is inserted into an end region of the receiving port 51 in the blow-by gas passage 50 via the seal member 8b. In this state, an outlet-side end of the air intake port 20 is fixed to the cylinder head 111 by fastening members (not shown). Thus, the blow-by gas passage 50 is directly connected to the cylinder head 111 via the PCV valve 5.

(21) As shown in FIG. 4, the blow-by gas passage 50 includes a chamber 53 between the receiving port 51 and the introduction port 52. The mating surface A is located in the chamber 53. Furthermore, in a state where the air intake apparatus main body 80 is mounted on the cylinder head 111, the introduction port 52 is disposed below the chamber 53 and connected to the upper inner surface 10a of the surge tank 10. The passage sectional area of the chamber 53 is larger than those of the receiving port 51 and the introduction port 52. Therefore, the flow rate of the blow-by gas taken in from the receiving port 51 is reduced in the chamber 53 having a larger passage sectional area. In this case, the flow velocity is adjusted to a desired magnitude. The blow-by gas is introduced into the surge tank 10 from the introduction port 52 that opens on the upper inner surface 10a of the surge tank 10 in a state where the blow-by gas has reached an optimum flow velocity. Thus, the intake air and the blow-by gas are mixed in the optimum state in the surge tank 10.

(22) As shown in FIGS. 5 and 6, both the receiving port 51 and the introduction port 52 are provided in the middle piece 82. The receiving port 51 from the gas passage 7 is disposed between the outlet 21a of the air intake pipe 20a and the outlet 21b of the air intake pipe 20b (see FIG. 6) adjacent to each other on the side (the X1 side closer to the air intake 12) closer to the throttle valve 130 (see FIG. 1). Furthermore, the receiving port 51 faces the cylinder head 111 (see FIG. 4) in a state where the receiving port 51 is disposed between the outlet 21a and the outlet 21b. The introduction port 52 to the surge tank 10 is also disposed between the air intake pipe 20a and the air intake pipe 20b adjacent to each other on the side closer to the throttle valve 130 (air intake 12).

(23) The blow-by gas passage 50 is disposed on the concave side of the arcuate air intake port 20 (see FIG. 3) and between the air intake port 20 and the surge tank 10. Therefore, the blow-by gas passage 50 is enclosed in the air intake apparatus main body 80 by effectively using a space between a curved inner portion of the curved air intake port 20 and the cylinder block 112 (see FIG. 1).

(24) As shown in FIG. 1, EGR gas, which is a portion of exhaust gas discharged from the cylinders 2 (combustion chambers 6) to the outside, is recirculated to the engine 110 through the air intake apparatus 100. The EGR gas separated from the exhaust gas is cooled to a predetermined temperature (about 100 C.) by an EGR cooler 9 and then introduced into the air intake apparatus main body 80. Specifically, as shown in FIGS. 2 and 3, the air intake apparatus main body 80 includes the EGR gas passage 40 that distributes the EGR gas to each of the air intake pipes 20a to 20d. The inner peripheral side of the EGR gas passage 40 is constituted by the upper piece 81, and the outer peripheral side thereof is constituted by the EGR gas piece 84. The EGR gas passage 40 includes an EGR gas inlet 41 and an EGR gas distributor 42 (see FIG. 3). The EGR gas distributor 42 is formed in a hierarchically branched tournament shape. An EGR gas inlet (not shown) is provided at the downstream end of the EGR gas distributor 42 divided in a tournament shape, and the EGR gas inlet communicates with each of the air intake pipes 20a to 20d.

Effects of First Embodiment

(25) According to the first embodiment, the following effects can be obtained.

(26) According to the first embodiment, as hereinabove described, the air intake apparatus 100 includes the blow-by gas passage 50 formed inside the air intake apparatus main body 80 by bonding the upper piece 81 and the middle piece 82 to each other. Thus, the blow-by gas passage 50 does not project (does not protrude) outward from the outer wall surface of the air intake apparatus main body 80, and hence it is possible to significantly reduce or prevent an increase in the size of the air intake apparatus main body 80. Furthermore, the blow-by gas passage 50 includes the receiving port 51 that directly receives the blow-by gas from the cylinder head 111 of the engine 110 such that a hose member (connection member) that connects the cylinder head 111 to the blow-by gas passage 50 is not necessary. Thus, the number of components that constitute the air intake apparatus 100 can be reduced. Consequently, the air intake apparatus 100 downsized while significantly reducing or preventing an increase in the number of components can be obtained.

(27) In addition, the blow-by gas passage 50 is enclosed in (built into) the air intake apparatus main body 80, and hence the direct influence of outside air (running air in an engine room of a vehicle on which the engine 110 is mounted) on the blow-by gas that flows through the blow-by gas passage 50 is significantly reduced or prevented. Therefore, even when the engine 110 is operated under the condition of a low outside air temperature (below the freezing point), cooling of the warm blow-by gas from the crankcase 3 in the blow-by gas passage 50 is significantly reduced or prevented by heat received from the cylinder head 111 and the heat retaining property of the blow-by gas passage 50 itself. That is, it is possible to significantly reduce or prevent condensation and freezing of moisture contained in the blow-by gas for ventilating the crankcase 3 due to cooling in the blow-by gas passage 50.

(28) According to the first embodiment, the opening 81e that opens in the mating surface A is provided in the upper piece 81, and the opening 82e that opens in the mating surface A is provided in the middle piece 82. Furthermore, the blow-by gas passage 50 is formed by bonding the upper piece 81 and the middle piece 82 to each other such that the openings 81e and 82e communicate with each other. Thus, when the upper piece 81 and the middle piece 82 are bonded to each other, the openings 81e and 82e that open in the mating surface A are joined together such that the continuous blow-by gas passage 50 that extends from the receiving port 51 to the introduction port 52 can be formed inside the air intake apparatus main body 80. In other words, it is not necessary to incorporate a dedicated member for forming the blow-by gas passage 50 in the air intake apparatus main body 80, and hence it is possible to significantly reduce or prevent an increase in the number of components that constitute the air intake apparatus main body 80.

(29) According to the first embodiment, the blow-by gas passage 50 includes the chamber 53 provided between the receiving port 51 and the introduction port 52 and having a passage sectional area larger than those of the receiving port 51 and the introduction port 52. Thus, the flow velocity of the blow-by gas taken in from the receiving port 51 can be reduced in the chamber 53 and adjusted to a desired flow velocity. Therefore, the blow-by gas can be introduced into the surge tank 10 from the introduction port 52 at the optimum flow velocity, and hence the intake air and the blow-by gas can be mixed in the optimum state in the surge tank 10.

(30) According to the first embodiment, the introduction port 52 is disposed between the air intake pipes 20a and 20b. Thus, the blow-by gas passage 50 including the introduction port 52 can be efficiently disposed in the air intake apparatus main body 80 by effectively using an empty space between the air intake pipes 20a and 20b. Therefore, downsizing of the air intake apparatus main body 80 can be easily achieved.

(31) According to the first embodiment, the introduction port 52 is disposed between the air intake pipes 20a and 20b on the side closer to the throttle valve 130. Thus, the blow-by gas can be rapidly mixed with the intake air by effectively using air flow immediately after the air flow passes through the throttle valve 130 into the surge tank 10. Therefore, the intake air (mixed air of fresh air and the blow-by gas) that has been sufficiently mixed with the blow-by gas in the surge tank 10 can be easily distributed to a plurality of air intake pipes 20a to 20d.

(32) According to the first embodiment, the receiving port 51 faces the cylinder head 111 and is disposed between the outlets 21a and 21b of the adjacent air intake pipes 20a and 20b. Thus, the cylinder head 111 and the receiving port 51 of the blow-by gas passage 50 can be easily connected to each other by simply connecting the air intake apparatus main body 80 to the cylinder head 111 of the engine 110. In addition, the receiving port 51 can be efficiently disposed in the air intake apparatus main body 80 by effectively using the empty space between the air intake pipes 20a and 20b. Therefore, downsizing of the air intake apparatus main body 80 can be easily achieved.

(33) According to the first embodiment, the blow-by gas passage 50 is disposed on the concave side of the arcuate air intake port 20 and between the air intake port 20 and the surge tank 10. Thus, the blow-by gas passage 50 can be enclosed by effectively using the space between the air intake port 20 and the engine 110, and hence the air intake apparatus main body 80 can be downsized. Furthermore, the air intake apparatus main body 80 is downsized, and hence the mountability of the air intake apparatus main body 80 in an engine room of an automobile can be improved.

(34) According to the first embodiment, in a state where the air intake apparatus main body 80 is mounted on the cylinder head 111, the introduction port 52 of the blow-by gas passage 50 is disposed below the chamber 53 and connected to the upper inner surface 10a of the surge tank 10. Thus, the blow-by gas can be introduced into the surge tank 10 from the upper inner surface 10a where air flow stagnates due to deviation from main flow of the intake air that flows into the surge tank 10, and hence the intake air and the blow-by gas can be homogeneously mixed. Furthermore, the introduction port 52 is disposed below the chamber 53, and hence when the blow-by gas flows through the blow-by gas passage 50, it is possible to prevent accumulation of a large amount of moisture (condensed water) contained in the blow-by gas in the blow-by gas passage 50.

(35) According to the first embodiment, the receiving port 51 faces the cylinder head 111 and is disposed between the outlets 21a and 21b of the adjacent air intake pipes 20a and 20b on the side closer to the throttle valve 130. Thus, not only the introduction port 52 but also the receiving port 51 is disposed between the outlets 21a and 21b of the air intake pipes 20a and 20b adjacent to each other on the side closer to the throttle valve 130, and hence the path length of the blow-by gas passage 50 can be minimized.

Second Embodiment

(36) A second embodiment is now described with reference to FIGS. 7 and 8. In this second embodiment, an example in which a blow-by gas passage 250 (an example of an external gas passage) is constituted by three members of an upper piece 281, a middle piece 282, and a lower piece 283 is described.

(37) An air intake apparatus 200 according to the second embodiment is mounted on an in-line four-cylinder engine 110. As shown in FIG. 7, in the air intake apparatus 200, an air intake apparatus main body 280 is formed by bonding the upper piece 281, the middle piece 282, the lower piece 283, and an EGR gas piece 284 to each other by vibration welding. As shown in FIG. 8, vibration welding is performed in a state where a bonding portion 281a of the upper piece 281 and a bonding portion 282a of the middle piece 282 face each other, and a bonding portion 282b of the middle piece 282 and a bonding portion 283a of the lower piece 283 face each other. Thus, the blow-by gas passages 250 as well as air intake pipes 220a to 220d is formed.

(38) The inner wall surface 250a of the blow-by gas passage 250 is formed by a mating surface A between the bonding portion 281a and the bonding portion 282a and a mating surface B (an example of a split plane) between the bonding portion 282b and the bonding portion 283a. The upper piece 281 alone includes an opening 281e (see FIG. 8) that opens in the mating surface A, and the middle piece 282 alone includes an opening 282e that opens in the mating surface A and an opening 282f (see FIG. 8) that opens in the mating surface B. The lower piece 283 alone includes an opening 283e (see FIG. 8) that opens in the mating surface B. The opening 281e and the opening 282e have the same sectional shape, and the opening 282f and the opening 283e have the same sectional shape. The upper piece 281 and the middle piece 282 are circumferentially bonded to each other such that the openings 281e and 282e communicate with each other, and the middle piece 282 and the lower piece 283 are circumferentially bonded to each other such that the openings 282f and 283e communicate with each other. Thus, one blow-by gas passage 250 is formed solely in the air intake apparatus main body 280 separately from the air intake pipes 220a to 220d.

(39) The blow-by gas passage 250 includes a receiving port 251 (an example of an external gas receiving port) that directly receives blow-by gas from a cylinder head 111 and an introduction port 252 (an example of an external gas introduction port) that introduces the blow-by gas into a surge tank 210. In addition, a chamber 253 is provided between the receiving port 251 and the introduction port 252. In a state where the air intake apparatus main body 280 is mounted on the cylinder head 111, the introduction port 252 is disposed below the chamber 253 and connected to the upper inner surface 210a of the surge tank 210. The passage sectional area of the chamber 253 is larger than those of the receiving port 251 and the introduction port 252. Therefore, the blow-by gas flows from the receiving port 251 to the chamber 253, is guided to the introduction port 252 while being turned back in the chamber 253, and is introduced into the surge tank 210.

(40) The blow-by gas passage 250 bridges the exit side of an air intake port 220 and the surge tank 210 inward of the curve of the air intake port 220. Therefore, the air intake port 220 that extends in a bow shape upward from a bottom portion of the surge tank 210 is also connected by the blow-by gas passage 250, and the rigidity of the air intake apparatus main body 280 made of resin is enhanced. The remaining structures of the second embodiment are similar to those of the aforementioned first embodiment.

Effects of Second Embodiment

(41) According to the second embodiment, as hereinabove described, the air intake apparatus 200 includes the blow-by gas passage 250 formed inside the air intake apparatus main body 280 by bonding the upper piece 281, the middle piece 282, and the lower piece 283 to each other. Thus, the blow-by gas passage 250 does not project outward from the air intake apparatus main body 280, and hence it is possible to significantly reduce or prevent an increase in the size of the air intake apparatus main body 280. Furthermore, the receiving port 251 that directly receives the blow-by gas from the cylinder head 111 of the engine 110 is provided in the blow-by gas passage 250 such that a hose member (connection member) that connects the cylinder head 111 to the blow-by gas passage 250 is not necessary, and hence the number of components that constitute the air intake apparatus 200 can be reduced. Consequently, the air intake apparatus 200 downsized while significantly reducing or preventing an increase in the number of components can be obtained.

(42) According to the second embodiment, the opening 281e that opens in the mating surface A is provided in the upper piece 281, and the opening 282e that opens in the mating surface A is provided in the middle piece 282. Furthermore, the opening 282f that opens in the mating surface B is provided in the middle piece 282, and the opening 283e that opens in the mating surface B is provided in the lower piece 283. In addition, the blow-by gas passage 250 is formed by bonding the upper piece 281 and the middle piece 282 to each other such that the openings 281e and 282e communicate with each other and bonding the middle piece 282 and the lower piece 283 to each other such that the openings 282f and 283e communicate with each other. Thus, the openings 281e and 282e that open in the mating surface A are joined together, and the openings 282f and 283e that open in the mating surface B are joined together such that the continuous blow-by gas passage 250 that extends from the receiving port 251 to the introduction port 252 can be easily formed inside the air intake apparatus main body 280. The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

Modified Examples

(43) The embodiments disclosed this time must be considered as illustrative in all points and not restrictive. The range of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and all modifications (modified examples) within the meaning and range equivalent to the scope of claims for patent are further included.

(44) For example, while the blow-by gas passage 50 is formed by bonding the upper piece 81 and the middle piece 82 to each other in the aforementioned first embodiment, and the blow-by gas passage 250 is formed by bonding the upper piece 281, the middle piece 282, and the lower piece 283 to each other in the aforementioned second embodiment, the present invention is not restricted to this. The blow-by gas passage 50 may be formed inside the air intake apparatus main body by bonding four or more piece members to each other.

(45) While the blow-by gas passage 50 (250) is provided between the air intake pipes 20a (220a) and 20b (220b) adjacent to each other in each of the aforementioned first and second embodiments, the present invention is not restricted to this. For example, the blow-by gas passage 50 (250) may be provided along the air intake pipe 20a closest to the throttle valve 130.

(46) While the chamber 53 (253) having a larger passage sectional area is provided between the receiving port 51 (251) and the introduction port 52 (252) in each of the aforementioned first and second embodiments, the present invention is not restricted to this. The blow-by gas passage 50 may be formed without providing the chamber 53.

(47) While the blow-by gas is introduced into the surge tank 10 (210) via the blow-by gas passage 50 (250) in each of the aforementioned first and second embodiments, the present invention is not restricted to this. For example, EGR gas (exhaust recirculation gas) may be introduced as the external gas according to the present invention into the surge tank 10 (210) via the external gas passage enclosed in the air intake apparatus main body 80 (280).

(48) While the example in which no valve is provided in the air intake port 20 (220) to make the length of the air intake port 20 (220) (air intake path length) variable has been shown in each of the aforementioned first and second embodiments, the present invention is not restricted to this. For example, the present invention may be applied to an air intake apparatus including air intake pipes (air intake port) provided with a valve that switches the air intake path length.

(49) While the present invention is applied to the air intake apparatus 100 (200) mounted on the in-line four-cylinder engine 110 in each of the aforementioned first and second embodiments, the present invention is not restricted to this. That is, the air intake apparatus according to the present invention may be applied to a multi-cylinder engine, a V-type multi-cylinder engine, or the like other than the in-line four-cylinder engine. Alternatively, the present invention may be applied to an air intake apparatus of an internal combustion engine (engine) mounted on equipment other than that for an automobile, for example. Furthermore, as the internal combustion engine, a gasoline engine, a diesel engine, a gas engine, or the like can be applied.

DESCRIPTION OF REFERENCE NUMERALS

(50) 10, 210: surge tank 10a, 210a: upper inner surface 20, 220: air intake port 20a to 20d, 220a to 220d: air intake pipe 21a, 21b: outlet 50, 250: blow-by gas passage (external gas passage) 51, 251: receiving port (external gas receiving port) 52, 252: introduction port (external gas introduction port) 53, 253: chamber 80, 280: air intake apparatus main body 81, 281: upper piece (piece) 81e, 82e, 281e, 282e, 282f, 283e: opening 82, 282: middle piece (piece) 83, 283: lower piece (piece) 100, 200: air intake apparatus 110: engine (internal combustion engine) 111: cylinder head 130: throttle valve