AIR INTAKE STRUCTURE FOR AN INTERNAL COMBUSTION ENGINE

Abstract

In an air intake structure for an internal combustion engine having a plurality of cylinders 7, the air intake structure includes: an intake passage 30 that introduces air from an air cleaner 106 into a combustion chamber 9; a fuel injector 22 that supplies fuel to the intake passage 30; and a throttle valve 55 that adjusts a flow rate of air to be introduced into the combustion chamber 9, wherein a plurality of intake passages 31, 32 for generating a tumble flow and a tumble valve 57 are provided downstream of the throttle valve 55, and a resonator 45 that connects the plurality of intake passages 31, 32 downstream of the tumble valve 57.The disclosed air intake structure for the internal combustion engine, although the resonator is provided in the internal combustion engine having a plurality of cylinders and generating the tumble flow, makes it possible to avoid an increase in the size of the internal combustion engine without providing a resonator for each intake port.

Description

[Technical field]

[0001] The present invention relates to an air intake structure for an internal combustion engine having a plurality of cylinders, in which a resonator is provided in an intake passage communicating with each cylinder and introducing intake air. [Background]

[0002] In recent years, research and development work has been conducted to improve fuel efficiency, contributing to energy efficiency and providing more people with easy and reliable access to sustainable and advanced energy. An air intake structure for an internal combustion engine, in which a resonator is provided in an intake duct communicating with the cylinders of the internal combustion engine, directs intake air to branch off from the intake duct and reduce intake noise, is commonly known. [State of the art document][Patent document]

[0003] Patent Document 1: JP 2011-94633 A [Summary of the Invention][Basic Problems to be Solved by the Invention]

[0004] Incidentally, in the present fuel efficiency improvement technique, in an internal combustion engine equipped with a tumble flow generation structure, a larger amount of intake air is required to generate the tumble flow, thus requiring a resonator with a large volume. In particular, in an internal combustion engine with multiple cylinders and multiple intake ports, a resonator is required for each intake port, resulting in the problem of requiring an increased engine size.

[0005] To solve the above problem, an object of the present application is to provide an internal combustion engine that enables cost reduction while achieving downsizing of the internal combustion engine. This also contributes to energy efficiency. [Means of solving the problem]

[0006] In view of the above problem, the present invention relates to an air intake structure for an internal combustion engine having a plurality of cylinders, the air intake structure comprising: an intake duct that directs air from an air filter into a combustion chamber; a fuel injector that supplies fuel to the intake port; and a throttle valve which adjusts a flow rate of the air to be introduced into the combustion chamber, whereby a plurality of intake ports for generating a tumble flow and a tumble valve are provided downstream of the throttle valve, and a resonator that connects the majority of intake ports downstream of the tumble valve.

[0007] According to the above configuration, the resonator connecting the plurality of intake ports is arranged downstream of the tumble valve, so that the flow rate of the tumble flow can be increased. Therefore, air intake can be performed in a state where the air-fuel mixture is swirled, so that the combustion of the internal combustion engine can be brought into an adequate combustion state. This enables an improvement in fuel efficiency and a reduction in unburned gases, and also enables the cost of the exhaust gas catalyst device to be reduced. In addition, the resonator is located between the plurality of intake ports, eliminating the need to arrange the resonator downstream of the tumble valve for each cylinder. This enables cost reduction and downsizing of the internal combustion engine.

[0008] In the above configuration, the resonator may include: a resonator chamber located in the center; and a communication hole connecting the plurality of intake ports to the resonator chamber, wherein a volume of the resonator chamber can be larger than a volume of the connection hole.

[0009] According to the above configuration, the volume of the resonator chamber is larger than that of the connecting hole, so that a tumble flow can be formed that responds well to changes in the opening degree of the throttle valve, the tumble valve, and the engine speed. Therefore, air intake can be performed in a state where the air-fuel mixture is further swirled, so that an adequate combustion state can be achieved. This enables an improvement in fuel efficiency and a reduction in unburned gases, while also reducing the cost of the catalyst device. Furthermore, it becomes possible to obtain an internal combustion engine with good acceleration responsiveness.

[0010] In the above configuration, the resonator may include: a resonator chamber located in the center; and a communication hole connecting the plurality of intake ports to the resonator chamber, wherein the resonator chamber may have inner walls (46a) each having an arcuate shape along each of the plurality of intake channels.

[0011] According to the above configuration, the volume of the resonator chamber can be increased as much as possible, so that a tumble flow can be formed that responds well to changes in the opening degree of the throttle valve, the tumble valve, and the engine speed. Therefore, air intake can be performed in a state where the air-fuel mixture is further swirled, so that an adequate combustion state can be achieved. This enables an improvement in fuel efficiency and a reduction in unburned gases, and also reduces the cost of the catalyst device. Furthermore, it becomes possible to obtain an internal combustion engine with good acceleration responsiveness. [Advantageous effects of the invention]

[0012] According to the present invention, it is possible to suppress an increase in the size of the internal combustion engine without providing a resonator for each intake port even though a resonator is provided in a tumble flow internal combustion engine having a plurality of cylinders. [Brief description of the drawings] Fig. 1 is an enlarged side view of a motorcycle to which an air intake structure for an internal combustion engine according to an embodiment of the present invention is attached. Fig. 2 is a left side view of the internal combustion engine. Fig. 3 is a longitudinal sectional view of the main components of the internal combustion engine. Fig. 4 is a bottom view of a cylinder head of the internal combustion engine. Fig. Figure 5 is a schematic diagram of the air intake structure for the internal combustion engine. Fig. 6 is an exploded perspective view of the main components of the air intake structure. Fig. 7 is a longitudinal sectional view taken along a direction orthogonal to a suction flow of a connecting pipe. Fig. 8 is a cross-sectional view in the direction of arrows VIII in Fig. 7. [Mode(s) of carrying out the invention]

[0013] Fig. 1 is a left side view of a motorcycle 100 to which an air intake structure for an internal combustion engine according to an embodiment of the present invention is mounted. The motorcycle 100 is illustrated as an example of a vehicle to which an internal combustion engine 1 according to the present invention is mounted, but the vehicle is not limited to a motorcycle as long as it is a vehicle to which an internal combustion engine is mounted.

[0014] A vehicle frame 110 of the motorcycle 100 includes: a head pipe 111 steerably supporting a front fork 102 for pivotally supporting a front wheel 101; a pair of left and right main frame members 112 extending rearward and downward from the head pipe 111; a pair of left and right engine mounts 113 continuously connected to front portions of the head pipe 111 and the left and right main frame members 112 and also extending rearward and downward under the main frame members 112; a pair of left and right swing frame members 114 connected to rear end portions of the main frame members 112 and extending downward; and a pair of left and right seat rails 115 extending rearward and upward from rear portions of the main frame members 112.

[0015] The internal combustion engine 1 is mounted on the vehicle frame 110 under the main frame members 112, while the front and rear wheels are suspended from the engine mounts 113 and the swing frame members 114. A swing arm 103, the front end of which is pivotally mounted on the swing frame members 114, extends rearwardly, and a rear wheel 104 is pivotally mounted at its rear end portion. An endless drive chain 66 is wound around a drive sprocket 65 mating with an output shaft 64 of the internal combustion engine 1 and a driven sprocket 105 mating with a rear axle.

[0016] An air cleaner 106 is arranged above the internal combustion engine 1, positioned at the rear of the head pipe 111 in the vehicle frame 110. A fuel tank 107 of a fuel supply device 120 is attached to both main frame members 112 of the vehicle frame 110 to cover a rear and an upper part of the air cleaner 106. A main seat 108 is provided at the rear of the fuel tank 107 and supported by the seat rails 115.

[0017] As in Fig. 2, a left side view of the internal combustion engine 1, the internal combustion engine 1 is a so-called unit with a transmission 60 in a crankcase 2. The internal combustion engine 1 is a four-stroke internal combustion engine with two cylinders (cylinders) 7. In the present embodiment, two cylinders 7 are formed, but it is sufficient to provide two or more cylinders 7 instead of two cylinders 7.

[0018] The internal combustion engine 1 is attached to the vehicle frame 110 with a crankshaft 20 aligned in the vehicle width direction (left-right direction).

[0019] As in Fig. 3, the internal combustion engine 1 comprises an upper and a lower half-cut crankcase 2 with an upper crankcase 2A and a lower crankcase 2B. In a front upper portion of the upper crankcase 2A, a cylinder block 3 is formed integrally with a forwardly inclined cylinder axis Lc of the two cylinders 7 (in Fig. 1 only the left cylinder 7 is shown).

[0020] A cylinder head 4 is mounted overlapping on the cylinder block 3, with a cylinder head cover 5 covering the cylinder head 4. An oil pan 6 is mounted below the crankcase 2.

[0021] The crankshaft 20 is rotatably mounted in the crankcase 2, and the transmission 60 is also installed at the rear of the crankshaft 20. A main shaft 61 of the transmission 60 includes a clutch device (not shown) at a right end portion and is pivotally arranged parallel to the crankshaft 20, wherein a countershaft 62 is pivotally arranged parallel to the crankshaft 20 and slightly offset rearwardly on upper and lower clutch surfaces 2a of the crankcase 2. As shown in Fig. 1, the drive sprocket 65 described above fits onto a left shaft end of the countershaft 62 which projects through the crankcase 2, the countershaft 62 forming an output shaft 64 of the internal combustion engine 1.

[0022] As in Fig. 2, the cylinders 7 are formed in the cylinder block 3 of the internal combustion engine 1, wherein the pistons 8 reciprocating in the cylinders 7 fit slidably into the cylinders 7. The cylinders 7, the tops of the pistons 8 and a bottom of the cylinder head 4 facing the top of the pistons 8 form a combustion chamber 9. As shown in Fig. 3, a spark plug 19 is attached to the cylinder head 4 such that its front end faces the combustion chamber 9.

[0023] As in Fig. 3, an intake port 10 and an exhaust port 11 are formed in the cylinder head 4, which communicate with the combustion chamber 9. The internal combustion engine 1 is a four-valve internal combustion engine with two intake valves 17 and two exhaust valves 18 per cylinder 7. The intake valve 17 and the exhaust valve 18 are arranged in the cylinder head 4, each of which controls an intake quantity flowing from the intake port 10 into the combustion chamber 9 and an exhaust quantity expelled from the combustion chamber 9 into the exhaust port 11.

[0024] Fig. 4 is a bottom view of the cylinder head 4 seen from a counter surface 4a, which is matched to the cylinder block 3. On a combustion chamber ceiling 9a facing the piston top of the cylinder head 4, two intake valve openings 9b, which are opened and closed by the intake valve 17, and two exhaust valve openings 9c, which are opened and closed by the exhaust valve 18, are provided next to one another.

[0025] The surface of the combustion chamber ceiling 9a represents a curved, dome-shaped concave surface, with the intake valve openings 9b arranged next to each other on the left and right substantially on a rear half-surface of the combustion chamber ceiling 9a, while the exhaust valve openings 9c are arranged next to each other on the left and right substantially on a front half-surface of the combustion chamber ceiling 9a. The inner diameters of the exhaust valve openings 9c are smaller than the inner diameters of the intake valve openings 9b.

[0026] As in Fig. 3, in the cylinder head 4 the intake port 10 is curved rearward from the intake valve port 9b and the exhaust port 11 is curved forward from the exhaust valve port 9c.

[0027] In Fig. 4, the intake openings 10, 10 extending rearward from the intake valve openings 9b, 9b arranged next to each other on the left and right are brought together on an upstream side. As in Fig. 3, a connecting piece 40 is connected to an upstream end of the intake opening 10.

[0028] As in Fig. 4, the outlet openings 11, 11 extending forward from the outlet valve openings 9c, 9c arranged next to each other on the left and right are brought together on a downstream side. As shown in Fig. 3, an outlet pipe 13 is connected to a downstream end of the outlet opening 11.

[0029] As in Fig. As shown in Figure 4, a spark plug hole 4b is provided in the combustion chamber ceiling 9a of each combustion chamber 9 in the cylinder head 4 near the cylinder axis Lc in the central part, into which a spark plug 19 is screwed, with the intake valve channels 9b, 9b and the exhaust valve channels 9c, 9c being largely open around the spark plug hole 4b. The spark plug 19 screwed into the spark plug hole 4b in the central region of the combustion chamber ceiling 9a causes an electrode portion at its frontmost end to face the combustion chamber 9.

[0030] As in Fig. 3, in the intake valve 17, a valve stem part 17s is slidably supported by a valve guide 23 fitting to an upper wall of the intake port 10, and at a frontmost end of the valve stem part 17s, a shield member 17u opens and closes the intake valve port 9b.

[0031] Similarly, in the exhaust valve 18, a valve stem portion 18s is slidably supported by a valve guide 23 fitting to an upper wall of the exhaust port 11, and at a foremost end of the valve stem portion, an umbrella member 18u 18s opens and closes the exhaust valve port 9c.

[0032] The valve mechanism controlling the intake valve 17 and the exhaust valve 18 is of the DOHC type. An intake camshaft 71 and an exhaust camshaft 72, which are parallel to each other, rotate. In this way, an intake cam 73 provided on the intake camshaft 71 and an exhaust cam 74 provided on the exhaust camshaft 72 press valve lifters 75, 75, which cover upper end portions of the intake valve 17 and the exhaust valve 18, respectively. The intake valve 17 and the exhaust valve 18 reciprocate in time according to the rotational position of the crankshaft 20, opening and closing the intake valve port 9b and the exhaust valve port 9c.

[0033] The connecting piece 40 for sucking in the outside air is connected to an upstream end of the intake opening 10. An intake pipe 56, in which a tumble valve 57 is arranged, and a throttle valve housing 54, in which a throttle valve 55 is arranged, are connected to an upstream end of the connecting piece 40.

[0034] As in Fig. 1, an air funnel 35 is mounted on an upstream side of the throttle valve housing 54. The air funnel 35 is fitted into the clean-side interior of the outside air purifying air filter 106, and the purified intake air is supplied to the internal combustion engine 1. The intake port 10, the connecting piece 40, the intake pipe 56, the throttle valve housing 54, and the air funnel 35 form an intake duct 30.

[0035] The throttle valve 55 is rotatably and pivotably supported within the throttle valve housing 54 by a throttle valve shaft 55a which is oriented substantially horizontally and perpendicular to the flow direction of the intake passage 30 and variably controls the passage area of ​​the intake passage 30 to adjust the amount of intake air from the upstream side.

[0036] The exhaust pipe 13 is connected to the exhaust port 11, and a catalyst device 26 incorporating a three-way catalyst or the like is arranged along the exhaust pipe 13 to purify the exhaust gas. A downstream end of the exhaust pipe 13 is connected to a muffler 14, and the muffler 14 reduces the exhaust noise. The exhaust port 11, the exhaust pipe 13, the catalyst device 26, and the muffler 14 form an exhaust passage 16.

[0037] Then, the intake passage 30 is divided into a main passage 30A and a tumble passage 30B by a partition wall 33 between an intake passage from the intake pipe 56 via the connecting piece 40 to the intake port 10 and a downstream portion of the intake pipe 56 to a curved portion of the intake port 10, each of the intake passages defining a substantially semicircular cross section.

[0038] The tumble channel 30B is rotatably mounted on a tumble valve shaft 57a, which runs parallel to the throttle valve shaft 55a, wherein the flow rate is changed by the tumble valve 57.

[0039] A fuel injection valve 22 is attached to the intake pipe 56. The fuel injection valve 22 opens into an upper outer portion of the main passage 30A to inject and supply the fuel thereto.

[0040] Fig. 5 is a schematic diagram showing an air intake structure for the internal combustion engine according to the present embodiment. The internal combustion engine in the present embodiment is a two-cylinder internal combustion engine, wherein the intake passage 30 includes a first intake passage 31 and a second intake passage 32. The first intake passage 31 and the second intake passage 32 each include the throttle valve 55 and the tumble valve 57 for controlling the intake air. The connecting port 40 is connected to the intake port 10 via a first gasket 51 and an O-ring 53, and to the intake pipe 56 via a second gasket 52 and an O-ring 53 (see Fig. 5 and Fig. 6).

[0041] As in Fig. 6, the connecting piece 40 comprises: a first circular pipe section 41 forming the first intake passage 31 and a second circular pipe section 42 forming the second intake passage. The first circular pipe section 41 and the second circular pipe section 42 are arranged such that the central axes of the circular pipes run substantially parallel to each other, wherein the outer peripheral wall sections 41a and 42a of the first circular pipe section 41 and the second circular pipe section 42 are connected to each other by a pair of connecting wall sections 43.

[0042] The first circular pipe section 41 is divided by a partition plate section 41b in the intake flow direction into a first main flow channel 31A and a first tumble flow channel 31B. The second circular pipe section 42 is also divided by a partition plate section 42b in the intake flow direction into a second main flow channel 32A and a second tumble flow channel 32B.

[0043] The interior space defined by the first circular tube portion 41, the second circular tube portion 42, and the pair of connecting wall portions 43 serves as a resonator chamber 46. A wall surface located between the pair of connecting wall portions 43 of the first circular tube portion 41 serves as a partition wall portion 41c that separates the first intake passage 31 and the resonator chamber 46. A wall surface connecting the pair of connecting wall portions 43 of the second circular tube portion 42 serves as a partition wall portion 42c that separates the second intake passage 32 from the resonator chamber 46. As shown in Fig. As shown in Fig. 7, the partition wall portions 41c and 42c constitute inner walls 46a of the resonator chamber 46, which are arcuate along the first intake passage 31 and the second intake passage 32. Since the inner walls 46a are arcuate along the first intake passage 31 and the second intake passage 32, the resonator chamber 46 can be designed to be spacious.

[0044] The first seal 51 and the second seal 52, which are located at a downstream and an upstream end of the connecting piece 40, are plate-shaped elements.

[0045] The first seal 51 has a first main flow passage opening part 51aA, a first tumble flow passage opening part 51aB, a second main flow passage opening part 51bA and a second tumble flow passage opening part 51bB, the openings of which correspond to the first main flow passage 31A, the first tumble flow passage 31B, the second main flow passage 32A and the second tumble flow passage 32B, respectively.

[0046] Similarly, the second seal 52 has a first main flow passage opening part 52aA, a first tumble flow passage opening part 52aB, a second main flow passage opening part 52bA and a second tumble flow passage opening part 52bB, the openings of which correspond to the first main flow passage 31A, the first tumble flow passage 31B, the second main flow passage 32A and the second tumble flow passage 32B, respectively.

[0047] The middle portions of the first gasket 51 and the second gasket 52 serve as closed portions 51c and 52c closing both ends of the resonator chamber 46 of the connecting pipe, and the partition wall portions 41c and 42c and the closed portions 51c and 52c covering the above-mentioned two ends form the resonator chamber 46.

[0048] As in the Fig. 7 and Fig. As shown in Figure 8, the partition wall portions 41c and 42c have a connecting hole 47 that serves as a connecting portion connecting the resonator chamber 46, the first tumble flow channel 31B, and the second tumble flow channel 32B, wherein the resonator chamber 46 and the connecting hole 47c form the resonator 45. The volume of the connecting hole 47 is smaller than the volume of the resonator chamber 46.

[0049] With the formation of the air intake structure for the internal combustion engine in the present embodiment as described above, the following effects are achieved.

[0050] According to the present embodiment, an air intake structure for an internal combustion engine having a plurality of cylinders includes: the intake passage 30 that introduces air from the air cleaner 106 into the combustion chamber 9; the fuel injector 22 that supplies fuel to the intake passage 30; and the throttle valve 55 that adjusts a flow rate of air to be introduced into the combustion chamber 9, wherein the first intake passage 31 and the second intake passage 32 for generating a tumble flow and the tumble valve 57 are provided downstream of the throttle valve 55, and the resonator 45, downstream of the tumble valve 57, connects the first intake passage 31 and the second intake passage 32. Therefore, the resonator 45 connecting the plurality of intake ports is arranged downstream of the tumble valve 57 so that the flow rate of the tumble flow can be increased.Therefore, air intake can be performed in a state where the air-fuel mixture is swirled, so that the combustion of the internal combustion engine 1 can be brought into an adequate combustion state. This enables an improvement in fuel efficiency and a reduction in unburned gases, and also allows the cost of the exhaust gas catalyst device 26 to be reduced. Furthermore, the resonator 45 is arranged between the first intake port 31 and the second intake port 32. This eliminates the need to arrange a resonator 45 for each cylinder downstream of the tumble valve 57. This enables a cost reduction and downsizing of the internal combustion engine 1.

[0051] Furthermore, the resonator 45 includes: the resonator chamber 46 located at the center; and the communication hole 47 connecting the first intake port 31 and the second intake port 32 to the resonator chamber 46. The volume of the resonator chamber 46 is larger than the volume of the communication hole 47, so that a tumble flow can be formed that responds well to a change in the opening degree of the throttle valve 55, the tumble valve 57, and the engine speed. Therefore, air intake can be performed in a state where the air-fuel mixture is further swirled, so that an adequate combustion state can be achieved. This enables an improvement in fuel efficiency and a reduction in unburned gases, which also makes it possible to reduce the cost of the catalyst device 26.In addition, it becomes possible to obtain an internal combustion engine 1 with good acceleration responsiveness.

[0052] Furthermore, the resonator 45 includes the resonator chamber 46 located at the center; and the communication hole 47 connecting the first intake port 31 and the second intake port 32. The resonator chamber 46 includes inner walls 46a each having an arc shape along the first intake port 31 and the second intake port 32, so that the volume of the resonator chamber 46 can be increased as much as possible. Therefore, a tumble flow can be generated that responds well to a change in the opening degree of the throttle valve 55, the tumble valve 57, or the engine speed. Therefore, air intake can be performed in a state where the air-fuel mixture is further swirled, so that an adequate combustion state can be achieved. This enables an improvement in fuel efficiency and a reduction in unburned gases, and also makes it possible to reduce the cost of the catalyst device.In addition, it will be possible to obtain an internal combustion engine with good acceleration responsiveness.

[0053] Embodiments of the present invention have been described so far. However, the present invention is not limited to the above-described embodiments, and various changes can be made in the configuration without departing from the concept of the present invention. Suffice it to say that a vehicle, an internal combustion engine, and the like can be formed into various shapes within the concept of the present invention. For example, in one embodiment of the present invention, the valve mechanism may be formed into a DOHC type. However, the present invention is not limited thereto. [Reference drawing list] 1 combustion engine 7 cylinders 9 Combustion chamber 22 Fuel injection device 30 intake duct 31 First intake duct 32 Second intake duct 45 Resonator 46 Resonator chamber 46a Interior walls 47 Connection hole 55 throttle valve 57 Tumble valve 106 air filters QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2011-94633 A

[0003]

Claims

[1] An air intake structure for an internal combustion engine having a plurality of cylinders (7), the air intake structure comprising: an intake duct (30) which introduces air from an air filter (106) into a combustion chamber (9); a fuel injector (22) supplying fuel to the intake passage (30); and a throttle valve (55) which adjusts a flow rate of the air to be introduced into the combustion chamber (9), wherein a plurality of intake channels (31, 32) for generating a tumble flow and a tumble valve (57) are provided downstream of the throttle valve (55), and a resonator (45) connecting the plurality of intake ports (31, 32) downstream of the tumble valve (57). [2] The air intake structure for the internal combustion engine according to claim 1, wherein the resonator (45) comprises: a resonator chamber (46) arranged in a center; and a communication hole (47) connecting the plurality of intake channels (31, 32) to the resonator chamber (46), wherein a volume of the resonator chamber (46) is larger than a volume of the connecting hole (47). [3] The air intake structure for the internal combustion engine according to claim 1, wherein the resonator (45) comprises: a resonator chamber (46) arranged in a center; and a communication hole (47) connecting the plurality of intake channels (31, 32) to the resonator chamber (46), wherein the resonator chamber (46) has inner walls (46a) each having an arc shape along each of the plurality of intake channels (31, 32).

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