Intake device for multi-cylinder internal conbustion engine

Abstract: An intake device for first and second cylinder groups (3l,3r) comprises a pair of resonance chambers (Cr-l,Cr-r) and a pair of resonance passages (18l,18r). A communication chamber (Cs) is connected to the resonance chambers, and valves (28) permits the resonance chambers to be put into communication with each other via the communication chamber. The communication chamber and resonance chambers are each formed of a substantially tubular configuration disposed adjacent to one another but separated by partition walls in which are disposed the valves.

Description: The present invention relates to an intake device designed to provide an increase in volume efficiency of a multi-cylinder combustion engine by controlling the variation in intake gas pressure in an intake system. There is an already known intake device for multi-cylinder internal combustion engines, which is designed to increase the volume efficiency in a region from a lower speed to a higher speed by controlling the length and volume of the intake system in a variable manner in accordance with the operational condition of the engine to exhibit one of two effects: a resonance effect that variations in intake gas pressure resonate between cylinders which produce no suction interference and an inertia effect utilizing the fact that a negative pressure wave produced at the beginning of suction for every cylinder is reflected at an increased volume portion provided in the intake system back to an intake port (for example, see Japanese Patent Application Laid-open No 60-169627). The above intake device comprises a pair of resonance chambers defined in the increased volume portion provided in the intake system and communicating with groups of cylinders having such an order of ignition that any one of the cylinders is not ignited immediately before or after ignition of the other cylinders of the same group, and an on-off valve provided between the chambers for permitting the chambers to be put into and out of communication with each other, whereby controlling of the opening and closing of the on-off valve causes the intake system to be switched to a resonance supercharge system or an inertia supercharge system. Further, controlling of the opening and closing of another on-off valve provided between a pair of resonance passages connected to upstream sides of the pair of resonance chambers causes the speed region of the engine permitting exhibition of a resonance supercharge effect in a lower speed region to be switched at two stages, thereby increasing the volume efficiency over a totally wider speed region of the engine. When such intake device is disposed in a V-shaped space in a V-shaped multi-cylinder internal combustion engine, it is difficult to suitably dispose the resonance passages and the resonance chambers without hindering the suction efficiency, because the space is extremely narrow. An on-off valve capable of changing the suction characteristics is also provided in a resonance chamber assembly box provided with the resonance passages and the resonance chambers. However, the disposition of the on-off valve within the resonance chamber assembly box causes problems of not only an increase in size of the intake system to provide an interference with the layout thereof, but also of a complication of the structure, resulting in an increased cost of manufacture. Further, in an intake device which is designed to establish a resonance supercharge system or an inertia supercharge system by permitting the resonance passages and the resonance chambers to be put into or out of communication each other through the on-off valve, it is extremely difficult to set the volumes of the resonance passages and the resonance chambers so that any of the resonance supercharge effect and the inertia supercharge effect may be optimally exhibited. It is an object of the present invention to optimally exhibit any of a resonance supercharge effect and an inertia supercharge effect in an intake device designed to establish a resonance supercharge system and an inertia supercharge system by permitting the resonance passages and the resonance chambers to be put into or out of communication with each other through on-off valves. According to the present invention, there is provided an intake device for a multi-cylinder internal combustion engine, said engine including first and second groups of cylinders which have such an order of ignition that any one of the cylinders is not ignited immediately before or after ignition of the other cylinders in the same group, said intake device comprising: a pair of resonance chambers which communicate with the cylinders of the respective groups; and a pair of resonance passages which communicate at downstream sides thereof with said resonance chambers and at upstream sides thereof with the atmosphere via a throttle valve; and a communication chamber connected to the pair of resonance chambers via at least a pair of on-off valves such that when the on-off valves are opened, the pair of resonance chambers are communicated with each other via the communication chamber whereas when the on-off valves are closed, the volume of the communication chamber is cancelled for the resonance chambers, characterised in that the communication chamber and resonance chambers are each formed of a substantially tubular configuration disposed adjacent to one another but separated from one another by partition walls which are formed as at least partially common to each other, said on-off valves being provided in openings through common portions of the partition walls, and in that the valve opening area of each on-off valve opening into the communication chamber is smaller than the cross-sectional area of the communication chamber substantially normal to fluid flow downstream of the valve, when air flows from the resonance chamber to the communication chamber, so that the intake air flowing through the on-off valve from the resonance chamber to the communication chamber expands, this expansion substantially preventing the passage of a negative pressure wave across the valve and thus substantially preventing a resonance supercharging effect from occurring in the resonance chambers and resonance passages in certain operational ranges of the engine. With the above construction, even if the volume of each of the resonance chambers is set at a value enough to provide an optimal resonance supercharge effect, the volume of a chamber resulting from the communication of the resonance chambers with each other to establish an inertia supercharge system in a higher speed operation region can be set at a sufficiently large and optimal value proper by setting of the volume of the communication chamber. Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal sectional view of details of a V-type six cylinder internal combustion engine equipped with an intake device according to a first embodiment of the present invention; Fig. 2 is an enlarged partial plan view taken along a line XVIII-XVIII in Fig. 1; Fig. 3 is an enlarged partial plan view taken along a line XIX-XIX in Fig. 1; Fig. 4 is a sectional view taken along a line XX-XX in Fig. 2; and Fig. 5 is a sectional view taken along a line XXI-XXI in Fig. 2; Fig. 6 is a sectional view of an intake system, similar to Fig. 2, but illustrating a second embodiment of the present invention: Figs. 7 to 10 illustrate a third embodiment of the present invention, wherein Fig. 7 is a longitudinal sectional view of details of a V-type six cylinder internal combustion engine equipped with an intake device according to a third embodiment of the present invention; Fig. 8 is an enlarged partial plan view taken along a line XXIV-XXIV in Fig. 7; Fig. 9 is a sectional view taken along a line XXV-XXV in Fig. 8; Fig. 10 is a sectional view taken along a line XXVI-XXVI in Fig. 8: and Fig. 11 is a sectional view of an intake system, similar to Fig. 8, but illustrating a fourth embodiment of the present invention. Figs. 1 to 5 illustrate a first embodiment of the present invention. Referring to Figs. 1 and 2, a sixcylinder type internal combustion engine E comprises a pair of left and right engine blocks Bℓ and Br located in a V-shaped arrangement. Each of the left and right engine blocks Bℓ and Br comprises a cylinder block 1ℓ, 1r and a cylinder head 2ℓ, 2r joined or bonded to a deck surface of the cylinder block, respectively. Three left cylinders 3ℓ are formed in series in the left cylinder block 1ℓ, and three cylinders 3r are formed in series in the right cylinder block lr. The three left cylinders 3ℓ constitute a left cylinder group Cℓ. The three right cylinders 3r also constitute a right cylinder group Cr. These cylinders have such an order of ignition that any one of the cylinders is not ignited immediately before or after ignition of the other cylinders of the same group, i.e., intake valves 10 which will be described hereinafter are not overlapped. A piston 4 is slidably received in each of the left and right cylinders 3ℓ and 3r in a usual manner. The pistons 4 are operatively connected to a crank shaft 6 through connecting rods 5. Each of the left and right cylinder heads 2ℓ and 2r is provided with a combustion chamber 7 and intake and exhaust ports 8 and 9 communicating with the combustion chamber 7. Each intake port 8 has an intake valve 10 provided therein for opening and closing the intake port 8, and each exhaust port 9 has an exhaust valve 11 provided therein for opening and closing the exhaust port 9. The intake and exhaust valves 10 and 11 may be opened and closed with a predetermined timing by a conventionally known valve operating mechanism 12. An intake system In which will be described hereinafter is connected to the plurality of intake ports 8 in the left and right cylinder heads 2ℓ and 2r, and a conventionally known exhaust system which is not shown is connected to the plurality of exhaust ports 9 in the left and right cylinder heads 2ℓ and 2r. The construction of the intake system In will be described below with reference to Figs. 2 to 5. The intake system In is disposed in a V-space C between the left and right cylinder blocks 1ℓ and lr and comprises an air cleaner Ac, an intake passage Pi connected to an outlet of the air cleaner Ac, a resonance chamber assembly box Bg having a pair of left and right resonance chambers Cr-ℓ and Cr-r and connected to a downstream end of the intake passage Pi, and an intake manifold Mi joined to those ends of the left and right cylinder blocks 1ℓ and lr at which the intake ports 8 are opened, thereby permitting the communication between the left and right resonance chambers Cr-ℓ and Cr-r and the right and left cylinder groups Cr and Cℓ respectively. The passage Pi is constructed with a throttle body 15 integrally connected to a downstream end of an intake passage 14 connected to the air cleaner Ac, as shown in Fig. 2. The intake passage 14 is formed into a hollow cylindrical shape so that an intake gas may be drawn thereinto from the air cleaner Ac. The throttle body 15 is bifurcated into left and right branch passages 18ℓ and 18r downstream its connection with the intake passage 14, and throttle valves 20ℓ and 20r are provided in the branch passages 18ℓ and 18r and controllable for opening and closing by a common control 19. The resonance chamber assembly box Bg is integrally connected to a downstream end of the throttle body 15 by bolts 16. It can be seen from Figs. 4 and 5 that the resonance chamber assembly box Bg is comprised of a substantially rectangular parallelepiped-shaped lower assembly box portion 21₁ opened at its upper surface and connected to the throttle body 15, a substantially rectangular parallelepiped-shaped upper assembly box portion 21₂ opened at its lower surface and formed integrally with an intake manifold Mi, and a plate-like valve unit 22 air-tightly secured at its upper and lower surfaces to the opened surfaces of the assembly box portions 21₁ and 21₂. These three components are assembled in a vertically stacked relation by bolts 23. It can be seen from Figs. 2 to 5 that the lower assembly portion 21₁ of the resonance chamber assembly box Bg is divided into left and right resonance passages 25ℓ and 25r parallel to each other and a communication chamber portion Cs as communication passages located between the left and right resonance passages 25ℓ and 25r by two partition walls 24ℓ and 24r extending in a direction of a crank shaft 6 of an engine, i.e., in a direction of a flow of an intake gas within the box Bg. Downstream ends of the left and right branch passages 18ℓ and 18r of the throttle body 15 communicate with upstream ends of the left and right resonance passages 25ℓ and 25r, respectively. The upper assembly box portion 21₂ is also divided into left and right parallel resonance chambers Cr-ℓ and Cr-r by a partition wall 24 curved like a crank. Such curved portion of the partition wall 24s is located just above the communication chamber portion Cs defined in the lower assembly box portion 21₁. Opened in the valve unit 22 are left and right inlet ports 26ℓ and 26r permitting upstream ends of the left and right resonance chambers Cr-ℓ and Cr-r to communicate with downstream ends of the corresponding resonance passages 25ℓ and 25r, respectively, left and right two valve bores 27ℓ and 27r which short-circuit the left and right resonance chambers Cr-ℓ and Cr-r and the resonance passages 25ℓ and 25r at points short of the inlet ports 26ℓ and 26r, and two valve bores 27s permitting left and right resonance chambers Cr-ℓ and Cr-r to communicate with each other through the communication chamber portion Cs. The valve unit 22 is further provided with on-off valves 28ℓ and 28r capable of opening the left and right two valve bores 27ℓ and 27r to short-circuit the left and right resonance chambers Cr-ℓ and Cr-r and the resonance passages 25ℓ and 25r, and an on-off valve 28s capable of opening the valve bore 27s to put the left and right resonance chambers Cr-ℓ and Cr-r into integral communication with each other through the communication chamber Cs. More specifically, two left and right valve stems 30ℓ and 30r are carried in the valve unit 22 to extend through central portions of inlet ports 26ℓ and 26r and the valve bores 27ℓ and 27r and adapted to be rotatably driven by a common actuator 29. Rectangular plate-like valve members 31a and 31b provided in the valve bores 27ℓ and 27r are secured to the valve stems 30ℓ and 30r by machine screws 32. A central valve stem 30s is also carried in the valve unit 22 to extend through the central valve bore 27s and adapted to be rotatably driven by another actuator 33, and a rectangular plate-like valve member 31s provided in the valve bore 27s is secured to the valve stem 30s by machine screws 32. The two actuators 29 and 30 are adapted to be controlled for operation in accordance with the operational condition of the engine, so that the opening and closing of the on-off valves 28ℓ, 28r and 28s may be controlled. Three elliptically-shaped left and right exhaust ports 34ℓ and 34r are opened in upper walls of the left and right resonance chambers Cr-ℓ and Cr-r along their longitudinal axis. The three exhaust ports 34ℓ of the left resonance chamber Cr-ℓ communicate with the three cylinders 3r (in which the suction sequence is not continuous), respectively, in the right cylinder block 1r located on the opposite side from the left resonance chamber Cr-ℓ through the intake manifold Mi, and the three exhaust ports 34r of the right resonance chamber Cr-r likewise communicate with the three cylinders 3ℓ (in which the suction sequence is not continuous), respectively, in the left cylinder block 1ℓ located on the opposite side from the right resonance chamber Cr-r through the intake manifold Mi. The operation of the first embodiment will be described below. The two actuators 29 and 33 are controlled for operation in accordance with the operational condition of the engine. For example, in a low-level lower speed operation condition in which the rotational speed of the engine is extremely low, when all the on-off valves 28ℓ, 28r and 28s are controlled to be closed as shown by a solid line in Figs. 2 to 5 to close their valve bores 27ℓ, 27r and 27s, the communication of the left and right resonance chambers Cr-ℓ and Cr-r is cut off, and the communication of the resonance passages 25ℓ and 25r corresponding to the left and right resonance chambers Cr-ℓ and Cr-r is also cut off. In this state, there are established two series of intake systems which are comprised of the branch passages 18ℓ and 18r for each cylinder group, the resonance passages 25ℓ and 25r for each cylinder group, left and right resonance chambers Cr-ℓ and Cr-r for each cylinder group, and left and right distributor pipes 35₁, 35₂, 35₃, 35₄, 35₅ and 35₆ for each cylinder group, i.e., two series of resonance supercharge intake system which produce no suction interference and each extend from the three cylinders 3ℓ and 3r to the outlet of the throttle body 15. Moreover, the volume of the resonance chambers Cr-ℓ and Cr-r is set such that the natural frequency of the resonance supercharge system may accord with the period of opening and closing of each intake valve 10 in the low-level lower speed rotation region of the engine and hence, the resonance supercharge effect is effectively exhibited to increase the volume efficiency in the low-level lower speed rotation region of the engine. When the rotational speed of the engine has been slightly increased into a high-level lower speed operational condition in which the rotational speed of the engine is higher than the low-level lower speed operation condition but lower than the middle speed operational condition the actuator 29 is operated to open the left and right on-off valves 28ℓ and 28r, thereby permitting the left and right resonance chambers Cr-ℓ and Cr-r and the resonance passages 25ℓ and 25r which have been hitherto in communication through the inlet ports 26ℓ and 26r to be short-circuited through the valve bores 27ℓ and 27r. This reduces the substantial length of the resonance passages 25ℓ and 25r to increase the natural frequency of the resonance supercharge system so as to substantially accord with the period of opening and closing of each intake valve 10 in the high-level lower speed rotation region of the engine. As a result, the resonance supercharge effect is effectively exhibited to increase the volume efficiency in the high-level lower speed rotation region of the engine. When the engine has been brought into a higher speed rotational condition, the actuator 33 is further operated to open the on-off valve 28s to put the left and right resonance chambers Cr-ℓ and Cr-r and the communication chamber Cs into communication with one another through the two valve bores 27s, thereby establishing an inertia supercharge distributing chamber Ch of a larger volume shown by a two-dashed line in Figs. 4 and 5, which commonly communicates with the left and right three cylinders 3ℓ and 3r. In this state, the above-described two series of resonance intake systems are cancelled and instead, an inertia supercharge system is established with a negative pressure wave produced in an intake stroke of the engine being reflected and turned in the larger volume inertia supercharge distributing chamber Ch and with a positive pressure wave being propagated to the intake port 8 of each cylinder 3ℓ, 3r. Moreover, the passage length of propagation of the negative positive pressure wave is reduced to enable the period of intake pressure to accord with the period of opening and closing of intake valve 10 during a high speed rotation of the engine. At this time, proper setting of the volume of the communication chamber Cs makes it possible to insure a larger volume of the inertia supercharge distributing chamber Ch required to enhance the inertia supercharge effect in a high speed rotation region of the engine, thereby effectively exhibiting the inertia supercharge effect in such operational region to increase the volume efficiency. It should be noted that even if the on-off valves 28l and 28r are in any of opened and closed states in such higher speed rotational region of the engine, there is no substantial influence, because the two series of resonance intake systems have been already cancelled and the inertia supercharge system has been established. By putting the left and right resonance chambers Cr-ℓ and Cr-r and the resonance passages 25l and 25r provided in the resonance assembly box Bg or the left and right resonance chambers Cr-ℓ and Cr-r into and out of communication with each other through the on-off valves 28ℓ, 28r and 28s as described above, it is possible to provide a higher volume efficiency in a wider operation range of from a lower speed to a higher speed. In addition, since the resonance chamber assembly box Bg is comprised of the vertically stacked upper and lower assembly box portions 21₂ and 21₁ and the valve unit 22, with the left and right resonance chambers Cr-ℓ and Cr-r being defined in the upper assembly box portion 21₂, with the pair of resonance passages 25ℓ and 25r and the communication chamber being defined in the lower assembly box portion 21₁ and with the inlet ports 26ℓ and 26r and the on-off valves 28ℓ, 28r and 28s being provided in the valve unit 22, it is possible to form the resonance chamber assembly box Bg extremely compactly and moreover to reduce the manufacturing cost thereof. A second embodiment of the present invention will be described below with reference to Fig. 6. Fig. 6 is a sectional view of an intake system, similar to Fig. 2, wherein the same reference characters as in the previously described first embodiment designate the same components. Omitted in the second embodiment are the left and right on-off valves 28ℓ and 28r for short-circuiting the left and right resonance chambers Cr-ℓ and Cr-r and the resonance passages 25ℓ and 25r, and the actuator 29 for driving the on-off valves 28ℓ and 28r, which have been used in the previous embodiment. The difference between this embodiment and the previous embodiment is that the resonance supercharge effect is obtained at two stages in the lower speed rotation region of the engine in the previous embodiment, whereas the resonance supercharge is obtained only at one stage in the lower speed rotation region of the engine in this embodiment. However, with regard to the compactification of the resonance chamber assembly box Bg and for the reduction of the manufacturing cost, this embodiment has the same effect as in the previous embodiment. In the first and second embodiments, the duties of the upper and lower assembly box portions 21₁ and 21₂ be may exchanged from each other and hence, the left and right resonance chambers Cr-ℓ and Cr-r can be defined in the lower assembly box portion 21₁, and the pair of resonance passages 25r and 25ℓ and the communication chamber Cs can be defined in the upper assembly box portion 21₂. Figs. 7 to 10 illustrate a third embodiment of the present invention. In this embodiment, an intake system In is disposed within a V-space C between the left and right cylinder blocks 1ℓ and lr and comprises an air cleaner Ac, an intake passage Pi connected to an outlet of the air cleaner Ac, a resonance chamber assembly box Bg having a pair of left and right resonance chambers Cr-ℓ and Cr-r and connected to a downstream end of the intake passage Pi, and an intake manifold Mi joined to those end faces of the left and right cylinder blocks 1ℓ and 1r at which the intake ports 8 are opened, thereby permitting the communication between the left and right resonance chambers Cr-ℓ and Cr-r and the right and left cylinder groups Cr and Cℓ, respectively. The intake passage Pi is constructed with a throttle body 15 being integrally connected to a downstream end of an intake passage 14 connected to the air cleaner Ac, as shown in Fig. 8. The intake passage 14 is formed into a hollow cylindrical shape so that an intake gas from the air cleaner Ac may be drawn thereinto, and the throttle body 15 is bifurcated, at a downstream of the junction with the intake passage 14, into left and right branch passages 18ℓ and 18r. Throttle valves 20ℓ and 20r are mounted within the branch passages 18ℓ and 18r, respectively and controllable for opening and closing by a common control 19. The resonance chamber assembly box Bg is integrally connected to a downstream end of the throttle body 15 by bolts 16. The resonance chamber assembly box Bg is comprised of a substantially rectangular parallelepiped-shaped lower assembly box body 21 opened at its upper surface and connected to the throttle body 15, and a lid 22 air-tightly mounted on the opened upper surface by bolts 23. The lid 22 is formed in an integral relation to the intake manifold Mi. It can be seen from Figs. 9 and 10 that the resonance chamber assembly box Bg is divided into left and right resonance chambers Cr-ℓ and Cr-r extending in parallel to each other and a communication chamber Cs located between the resonance chambers Cr-ℓ and Cr-r by two partition walls 24ℓ and 24r extending in a direction of a crank shaft 6 of an engine, i.e., in a direction of a flow of an intake gas within the box Bg. Downstream ends of the left and right branch passages 18ℓ and 18r of the throttle body 15 communicate with upstream ends of the left and right resonance chambers Cr-ℓ and Cr-r, respectively. On-off valves 25ℓ and 25r are mounted in the two partition walls 24ℓ and 24r for permitting the left and right resonance chambers Cr-ℓ and Cr-r and the communication chamber Cs to be put into and out of communication with each other. More specifically, quadrilateral valve bores 26ℓ and 26r are opened in the partition walls 24ℓ and 24r, respectively, and rotatable valve stems 27ℓ and 27r are inserted into central portions of the partition walls 24ℓ and 24r from the outside of the assembly box body 21 in a longitudinal direction of the intake system to extend through central portions of the valve bores 26ℓ and 26r, respectively. Rectangular plate-like valve members 28ℓ and 28r mounted in the valve bores 26ℓ and 26r are secured to the valve stems 27ℓ and 27r by machine screws 30, respectively. A portion of each of the valve stems 27ℓ and 27r passes through a rear end wall of the assembly box body 21 to project outside the rear end wall, and a conventionally known actuator 29 is connected to such projecting ends. The actuator 29 is controlled for operation in accordance with the operational condition of the engine so as to control the opening and closing of the on-off valves 25ℓ and 25r. For example, during a lower speed operation of the engine, the on-off valves 25ℓ and 25r may be controlled to be closed, and during a higher speed operation, the on-off valves 25ℓ and 25r may be controlled to be opened. The volume of the left and right resonance chambers Cr-ℓ and Cr-r with the on-off valves 25ℓ and 25r closed is set at a level such that an optimal resonance supercharge effect may be obtained in a lower speed rotation region of the engine. The volume of the communication chamber Cs is set at a level such that when the on-off valves 25ℓ and 25r have been controlled to be opened, thereby putting the left and right chambers Cr-ℓ and Cr-r and the communication chamber Cs into communication with one another to establish a larger-volume inertia supercharge distributing chamber Ch shown by a two-dashed line in Fig. 8, the volume of this larger-volume inertia supercharge distributing chamber Ch may be equal to a volume enough to provide an optimal inertia supercharge effect in a higher speed rotation region of the engine. Three elliptically-shaped left and right exhaust ports 34ℓ and 34r are opened in upper walls of the left and right resonance chambers Cr-ℓ and Cr-r along their longitudinal axis. The three exhaust ports 34ℓ of the left resonance chamber Cr-ℓ communicate with the three cylinders 3r (in which the suction sequence is not continuous), respectively, in the right cylinder block 1r located on the opposite side from the left resonance chamber Cr-ℓ through the intake manifold Mi, and the three exhaust ports 34r of the right resonance chamber Cr-r likewise communicate with the three cylinders 3ℓ (in which the suction sequence is not continuous), respectively, in the left cylinder block 19 located on the opposite side from the right resonance chamber Cr-r through the intake manifold Mi. The operation of the third embodiment will be described below. The actuator 29 is controlled for operation in accordance with the operational condition of the engine. For example, in a lower speed operation condition of the engine and when the on-off valves 25ℓ and 25r are controlled to be closed as shown by a solid line in Figs. 8 to 10 to close their valve bores 26ℓ and 26r, the communication of the left and right resonance chambers Cr-ℓ and Cr-r is cut off. In this state, there are established two series of intake systems comprising the resonance passages 18ℓ and 18r for each cylinder group, the left and right resonance chambers Cr-ℓ and Cr-r for each cylinder group, and the left and right distributor pipes 35₁, 35₂, 35₃, 35₄, 35₅ and 35₆ for each cylinder group, i.e., two series of resonance supercharge intake systems which produce no suction interference and each extend from the three cylinders 3ℓ, 3r to the outlet of the throttle body 15. Moreover, the volume of the resonance chambers Cr-ℓ and Cr-r is set such that the natural frequency of the resonance supercharge system may substantially accord with the period of opening and closing of each intake valve 10 in a lower speed rotation region of the engine. This ensures that the resonance supercharge effect is effectively exhibited to increase the volume efficiency in the lower speed rotation region of the engine. When the engine has been brought into a higher speed operation, the on-off valve 25ℓ and 25r are controlled to be opened, permitting the left and right resonance chambers Cr-ℓ and Cr-r and the communication chamber Cs to be put into communication with one another through the valve bores 26ℓ and 26r, thereby establishing a larger volume inertia supercharge distributing chamber Ch which communicates commonly with left and right three cylinders 3ℓ and 3r. In this state, the two series of resonance intake systems are cancelled and instead, an inertia supercharge system is established with a negative pressure wave produced in an intake stroke of the engine being reflected and turned in the larger volume inertia supercharge distributing chamber Ch and with a positive pressure wave being propagated to the intake port 8 of each cylinder 3ℓ, 3r. Moreover, the passage length of propagation of the negative and positive pressure waves is reduced to enable the period of intake pressure to accord with the period of opening and closing of intake valve 10 during a high speed rotation of the engine. Further, proper setting of the volume of the communication chamber Cs makes it possible to insure a larger volume of the inertia supercharge distributing chamber Ch required to enhance the inertia supercharge effect in a high speed rotation region of the engine, thereby effectively exhibiting the inertia supercharge effect in such operational region to increase the volume efficiency. In addition, since the pair of resonance chambers Cr-ℓ and Cr-r and the communication chamber are integrally defined within the resonance chamber assembly box Bg and moreover, since the on-off valves 25ℓ and 25r are provided in the partition walls 24ℓ and 24r, the structure of the intake system can be simplified and the shape thereof can be made compact. Fig. 11 is a sectional view of an intake system, similar to Fig. 10, wherein the same reference characters as in the previously-described third embodiment designate the same components. In this fourth embodiment, two valve bores 26ℓ', 26r' are opened in each of the left and right partition walls 24ℓ and 24r. These four valve bores 26ℓ' and 26r' may be opened and closed all together by the corresponding sets of two on-off valves 25ℓ' and 25r' secured to left and right valve stems 27ℓ' and 27r'. According to this embodiment, the left and right resonance chambers Cr-ℓ and Cr-r may be put in a moment into communication with the communication chamber Cs through the corresponding left and right sets of two valve bores 26ℓ' and 26r' to establish an inertia supercharge distributing chamber Ch. This enables an increase in responsivity thereof. At least in the preferred embodiments, there is thus provided a reasonable layout of on-off valves capable of changing suction characteristics in a resonance chamber assembly box comprising resonance passages and resonance chambers, wherein an intake device for a multi-cylinder internal combustion engine is provided, comprising a pair of resonance chambers independently communicating with groups of cylinders having such an order of ignition that any one of the cylinders is not ignited immediately before or after ignition of the other cylinders of the same group, and a pair of resonance passages communicating at their downstream sides with the resonance chambers and at their upstream sides with the atmosphere through a throttle valve, wherein the intake device further includes a resonance chamber assembly box which comprises an upper assembly box portion opened at a lower surface thereof, a lower assembly box portion opened at an upper surface thereof, and a plate-like valve unit dividing the opened surfaces of the upper and lower assembly box portions, the pair of resonance chambers being formed in one of the assembly box portions, the pair of resonance passages being formed in the other assembly box portion, and an on-off valve capable of changing suction characteristics of the engine being provided in the valve unit. With the above construction, and among the upper assembly box portion, the lower assembly box portion and the plate-like valve unit dividing the opened surface of the two assembly box portions, which constitute the resonance chamber assembly box, the left and right resonance chambers are defined in one of the assembly box portions, the resonance passages are formed in the other assembly box portion, and the on-off valve is provided in the valve unit. This provides a reasonable layout of the pair of resonance chambers, the pair of resonance passages and the on-off valve within the resonance chamber assembly box, leading to not only a compact intake system, but also to a simplified structure thereof, to enable a reduction in manufacture cost. Also, there is provided, at least in the preferred embodiments, an arrangement comprising an intake device for a multi-cylinder internal combustion engine, comprising a pair of resonance chambers independently communicating with groups of cylinders having such an order of ignition that any one of the cylinders is not ignited immediately before or after ignition of the other cylinders of the same group, and a pair of resonance passages communicating at their downstream sides with the resonance chambers and at their upstream sides with the atmosphere through a throttle valve, wherein the intake device further includes a resonance chamber assembly box which comprises an upper assembly box portion opened at a lower surface thereof, a lower assembly box portion opened at an upper surface thereof, and a plate-like valve unit dividing the opened surfaces of the upper and lower assembly box portions, the pair of resonance chambers being formed in one of the assembly box portions, the pair of resonance passages being formed in the other assembly box portion, and the valve unit including an on-off valve for changing the length of the resonance passages and another on-off valve for permitting the resonance chambers to be put into communication with each other, these valves being disposed in a plane where the valve unit lies. With the above construction, the on-off valve for changing the length of the resonance passages and the another on-off valve for permitting the pair of resonance chambers to be put into communication with each other are disposed in the same plane of the valve unit and therefore, it is possible to provide a further compactified intake system and a simplified structure.

Claims: An intake device for a multi-cylinder internal combustion engine, said engine including first and second groups of cylinders (3l,3r) which have such an order of ignition that any one of the cylinders (3l,3r) is not ignited immediately before or after ignition of the other cylinders (3l,3r) in the same group, said intake device comprising: a pair of resonance chambers (Cr-l, Cr-r) which communicate with the cylinders (31, 3r) of the respective groups; and a pair of resonance passages (181,18r) which communicate at downstream sides thereof with said resonance chambers (Cr-l, Cr-r) and at upstream sides thereof with the atmosphere via a throttle valve (20); and a communication chamber (Cs) connected to the pair of resonance chambers (Cr-l, Cr-r) via at least a pair of on-off valves (28) such that when the on-off valves (28) are opened, the pair of resonance chambers (Cr-l, Cr-r) are communicated with each other via the communication chamber (Cs) whereas when the on-off valves (28) are closed, the volume of the communication chamber (Cs) is cancelled for the resonance chambers (Cr-l, Cr-r), characterised in that the communication chamber (Cs) and resonance chambers (Cr-l, Cr-r) are each formed of a substantially tubular configuration disposed adjacent to one another but separated from one another by partition walls (24) which are formed as at least partially common to each other, said on-off valves (28) being provided in openings through common portions of the partition walls (24), and in that the valve opening area (27s) of each on-off valve (28) opening into the communication chamber (Cs) is smaller than the cross-sectional area of the communication chamber (Cs) substantially normal to fluid flow downstream of the valve (28), when air flows from the resonance chamber (Cr-l, Cr-r) to the communication chamber, so that the intake air flowing through the on-off valve (28) from the resonance chamber (Cr-l, Cr-r) to the communication chamber (Cs) expands, this expansion substantially preventing the passage of a negative pressure wave across the valve (28) and thus substantially preventing a resonance supercharging effect from occurring in the resonance chambers and resonance passages in certain operational ranges of the engine. The intake device according to claim 1, wherein a resonance chamber assembly box (Bg) is provided which comprises an upper assembly box portion (21₂) having an opened lower surface, a lower assembly box portion (21₁) having an opened upper surface, and a plate-like valve unit (22) between the upper and lower assembly box portions for separating their opened surfaces, said resonance chambers (Cr-l, Cr-r) being formed in one of the assembly box portions and said resonance passages (18l,18r) being formed in the other of the assembly box portions, said valve unit (22) being provided with said on-off valves (28). The intake device according to claim 2, wherein said valve unit (22) is provided with further on-off valves (28) for changing the length of the resonance chambers (Cr-l, Cr-r) through opening and closing operations thereof.

Inventors: ASAKI YASUAKI, HIRATANI MASAAKI, KITAMI YASUO, ASAKI, YASUAKI, HIRATANI, MASAAKI, KITAMI, YASUO
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 1990
Main classification: F02B27
IPC codes: F02B75, F02B27