Intake device for multi-cylinder internal combustion engine

Abstract: In an intake device for a multi-cylinder internal combustion engine, comprising a pair of resonance chambers (Cr-l,Cr-r) and a pair of resonance passages (18), the resonance chambers and the resonance passages are disposed in parallel in a V-space in the internal combustion engine with a dividing wall (24) interposed therebetween, thereby providing a compactified intake system. In the intake device, the resonance chambers are defined in one of upper and lower assembly box portions (21), while the resonance passages are defined in the other assembly box portion, and an on-off valve (25) capable of changing suction characteristics of the internal combustion engine being provided in a plate-like valve unit dividing opened surfaces of the two box portions. This enables a reasonable layout of the on-off valve. Further, in the intake device, the resonance chambers are capable of communicating with each other through a communication chamber having a predetermined volume. This ensures both of a resonance supercharge effect and an inertia supercharge effect.

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 of engine operation 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 accomplish 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. 169627/85). The above intake device comprises a pair of resonance chambers defined in the increased volume portion provided in the intake system and communicating with grips 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 accomplishment 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 create a difficulty in the layout thereof, but also 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 both the resonance supercharge effect and the inertia supercharge effect may be optimally accomplished. As examples of the prior art one may cite EP-A-0312979 and EP-A-0200930 which disclose the preamble of claim 1. Neither of these documents, however, teach an arrangement in which the above problems, with regard to the difficulties of suitable location, are overcome. Accordingly, the present invention provides an intake device for a multi-cylinder internal combustion engine, said engine being V-shaped and including a pair of engine blocks defining a V-space therebetween, cylinders being provided in the respective engine blocks and having 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 engine block, said intake device comprising: a pair of resonance chambers which communicate with the cylinders of the respective engine blocks; and a pair of resonance passages which communicate at downstream sides thereof with said pair of resonance chambers, respectively, and at upstream sides thereof with the atmosphere via a throttle valve, the resonance chambers and the resonance passages each being tubular elements formed of a substantially tubular configuration elongated to extend parallel to the crankshaft of the engine and being adjacent to one another; characterised in that four tubular elements defining the resonance chambers and the resonance passages are disposed adjacent one another but separated from one another by a plurality of partition walls which include one common partition wall separating one resonance chamber and associated resonance passage, and in that an on-off valve is provided in at least one of the plurality of partition walls for changing the intake characteristics of the engine. With the above construction, the resonance chambers and the resonance passages for establishing a resonance supercharge system are disposed in parallel in the V-space defined between the left and right groups of cylinder in the V-shaped multi-cylinder internal combustion engine and both of the resonance chambers and the resonance passages are reasonably contained within the V-space. This provides a compact sized intake system to enable an effective utilization of a space within an engine room. In a preferred embodiment 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 the intake characteristics of the engine being provided in the valve unit. With the above construction, among the upper assembly box portion, the lower assembly box portion and the plate-like valve unit dividing the opened surfaces 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 manufacturing cost. The on-off valve may include 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 preferably 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 reduction in the size of the intake system and a simplified structure. Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:- Figs. 1 to 5 illustrate a first embodiment of the present invention, wherein Fig. 1 is a front view in longitudinal section of details of a in-type six cylinder internal combustion engine equipped with an intake device according to a first embodiment of the present invention; Fig. 2 is a plan view of a cylinder block in the engine; Fig. 3 is an enlarged partial plan view taken along a line XI-XI in Fig. 1; Fig. 4 is a sectional view taken along a line XII-XII in Fig. 3; and Fig. 5 is a sectional view taken along a line XIII-XIII in Fig. 4; Fig. 6 is a sectional view of an intake system, similar to Fig. 3, but illustrating a second embodiment of the present invention; Figs. 7 and 8 illustrate a third embodiment of the present invention, Fig. 7 being a sectional view of an intake system, similar to Fig. 3, and Fig. 8 being a sectional view taken along a line XVI-XVI in Fig. 7; Fig. 9 is a longitudinal sectional view of details of a in-type six cylinder internal combustion engine equipped with an intake device according to the fourth embodiment of the present invention; Fig. 10 is an enlarged partial plan view taken along a line XVIII-XVIII in Fig. 9; Fig. 11 is an enlarged partial plan view taken along a line XIX-XIX in Fig. 9; Fig. 12 is a sectional view taken along a line XXXX in Fig. 10; and Fig. 13 is a sectional view taken along a line XXI XXI in Fig. 10. Figs. 1 to 5 illustrate a first embodiment of the present invention. Referring to Figs. 1 and 2, a six-cylinder 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 1r. 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 some group, i.e., the operation of the 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 crankshaft 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 within a V-space C between the left and right cylinder blocks 1ℓ and 1r 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 pipe 14 connected to the air cleaner Ac, as shown in Fig. 11. The intake pipe 14 is formed into a hollow cylindrical shape so that intake gas from the air cleaner Ac may be drawn thereinto, and the throttle body 15 is bifurcated, at a position downstream of its junction with the intake pipe 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 controlled for opening and closing by a common control means 19. The resonance chamber assembly box Bg is integrally connected to a downstream end of the throttle body 15 by bolts 16. As seen from Figs. 4 and 5, 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 upper 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 to provide a partition wall. These three components are assembled in a vertically stacked relation by bolts 23. It can be seen from Figs. 3 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 extending in parallel to each other in a direction of a crankshaft 6 of an engine, i.e., in a direction of a flow of 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. One of the resonance chambers Cr-ℓ is located above corresponding one of the resonance passages 25ℓ, and the other resonance chamber Cr-r is located above the other resonance passage 25r. 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, and left and right 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. The valve unit 22 is further provided with on-off valves 28ℓ and 28r which are capable of opening the left and right 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. More specifically, two valve stems 3Oℓ 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 31ℓ and 31r provided in the valve bores 27ℓ and 27r are secured to the valve stems 30ℓ and 30r by machine screws 32. The actuator 29 is adapted to be controlled for operation in accordance with the operational condition of the engine, so that the on-off valves 28ℓ and 28r may be controlled for opening and closing. For example, during a lower speed operation of the engine, the on-off valves 28ℓ and 28r may be closed, and during a higher speed operation of the engine, the on-off valves 28ℓ and 28r may be closed. Three elliptically-shaped left and right outlet ports 34ℓ and 34r are opened in upper walls of the left and right resonance chambers Cr-ℓ and Cr-r along their longitudinal axes. The three outlet ports 34ℓ of the left resonance chamber Cr-ℓ communicate with the three cylinders 3r (in which the intake 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 outlet ports 34r of the right resonance chamber Cr-r likewise communicate with the three cylinders 3ℓ (in which the intake sequence is not continuous), respectively, in the left cylinder block 1r located on the opposite side from the right resonance chamber Cr-r through the intake manifold Mi. The operation of this 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, the on-off valves 281 and 28r are controlled to be closed as shown by a solid line in Figs. 11 to 13 to close their valve bores 271 and 27r, so that the communication of the resonance passages 251 and 25r with the left and right resonance chambers Cr-l and Cr-r via the valves is cut off. In this state, there are established two series of intake systems for each cylinder group comprised of the branch passage 181, 18r, the resonance passage 251, 25r, left or right resonance chamber Cr-l, Cr-r, and left or right distributor pipes 35₁, 35₂, 35₃, 35₄, 35₅ and 35₆, i.e., two series of resonance supercharge intake systems which produce no suction interference and each extend from the three cylinders 31, 3r to the outlet of the throttle body 15. The length of such intake system is relatively long and 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 a resonance supercharge effect is effectively accomplished 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 actuator 29 is operated to open the left and right on-off valves 281 and 28r, so that the left and right resonance chambers Cr-1 and Cr-r and the resonance passages 251 and 25r which have been hitherto in communication with each other through the inlet ports 261 and 26r are short-circuited. This reduces the substantial length of the resonance passages 251 and 25r and causes the resonance passages 251 and 25r to serve as portions of the resonance chambers Cr-ℓ and Cr-r, thereby increasing the volume of the resonance chambers Cr-ℓ and Cr-r to ensure that the natural frequency of the resonance supercharge system is increased so as to substantially accord with the period of opening and closing of each intake valve 10 in the higher speed operation region of the engine. As a result, the resonance supercharge effect is effectively accomplished to increase the volume efficiency in the higher speed rotation region of the engine. By selectively permitting 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 to be short-circuited and to be put out of communication with each other through the on-off valves 28ℓ and 28r as described above, it is possible to provide a higher volume efficiency in a wider operation range of the engine from a lower speed to a higher speed. In addition, since the resonance chamber assembly box Bg is comprised of the upper and lower assembly box portions 21₂ and 21₁ and the valve unit 22 which are vertically stacked with the left and right resonance chambers Cr-ℓ and Cr-r being defined in the upper assembly box portion 21₂, with the resonance passages 25ℓ and 25r being defined in the lower assembly box portion 21₁ and with the inlet ports 26ℓ and 26r and the on-off valves 28ℓ and 28r being provided in the unit 22, it is possible to form the resonance chamber assembly box Bg extremely compactly and 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 the same intake system as in Fig. 3, wherein the same reference characters as in the previous embodiment designate the same components. In the second embodiment, two on-off valves 28ℓ₁, 28ℓ₂ and 28r₁ 28r₂ are used corresponding to the left and right on-off valves 28ℓ and 28r of the foregoing embodiment for short-circuiting the left and right resonance chambers Cr-ℓ and Cr-r and the resonance passages 25ℓ and 25r described in the previous embodiment, respectively. The on-off valves 28ℓ₁ and 28r₁ are mounted on valve stems 3Oℓ₁ and 30r₁ rotatably driven by an actuator 29₁, respectively and the on-off valves 28ℓ₂ and 28r₂ are mounted on valve stems 30ℓ₂ and 30r₂ rotatably driven by an actuator 29₂, respectively. According to this embodiment, all the on-off valves 28ℓ₁, 28r₁; 28ℓ₂, 28r₂ are closed in a lower speed rotation region of the engine, as in the previous embodiment, and the volume efficiency is increased in such lower speed rotation region. In a middle speed rotation region of the engine, one of the actuators 29₁ is driven to open the on-off valves 28ℓ₁ and 28r₁ closer to the inlet ports 26ℓ and 26r. This reduces the substantial length of the resonance passages 25ℓ and 25r slightly and causes portions of the resonance passages 25ℓ and 25r to serve as portions of the resonance chambers Cr-ℓ and Cr-r, thereby slightly increasing the substantial volume of the resonance chambers Cr-1 and Cr-r to ensure that the natural frequency of the resonance supercharge system is increased to be in substantial compliance with the period of opening and closing of each intake valve 10. Further, in a higher speed operation region of the engine, both the actuators 29₁ and 29₂ are driven to open all the on-off valves 28ℓ₁, 28r₁, 28ℓ₂ and 28r₂ as in the previous embodiment, thereby increasing the volume efficiency in such higher speed rotation region. According to the second embodiment, the natural frequency of the resonance supercharge system can be switched at three stages in this manner and therefore, the resonance supercharge effect is effectively accomplished in a wider range of engine operation from a lower speed operation region to a higher speed operation region to increase the volume efficiency of the engine. A third embodiment of the present invention will be described below with reference to Figs. 7 and 8. Figs. 7 and 8 are sectional views of the same intake system as in Figs. 3 and 4, wherein the same reference characters denote the same components. In the third embodiment, a resonance chamber assembly box Bg is connected to a downstream end of a throttle body 15' including a throttle valve 20' provided therein and is comprised of an assembly body 21₁' and a lid 21₂' covering an upper surface of the body 21₁'. The interior of the resonance chamber assembly box Bg is divided laterally by a dividing wall 24' extending longitudinally of the crankshaft 6. A pair of valve units 22ℓ' and 22r' forming partition walls are mounted on the left and right sides of the dividing wall 24' and sandwiched vertically between the assembly box body 21₁' and the lid 21₂', and a pair of resonance passages 25ℓ' and 25r' are defined between the left and right valve units 22ℓ' and 22r' and the dividing wall 24'. Left and right resonance chambers Cr-ℓ, Cr-r are defined outside the left and right valve units 22ℓ' and 22r', and the two resonance chambers Cr-ℓ and Cr-r communicate with downstream ends of the resonance passages 25ℓ' and 25r' through inlet ports 26ℓ' and 26r' made in the valve units 22ℓ' and 22r' respectively. Valve bores 27ℓ' and 27r' are opened in the valve units 22ℓ' and 22r', respectively, and on-off valves 28ℓ' and 28r' are mounted for opening and closing the valve bores 27ℓ' and 27r' and connected to an actuator 29. The on-off valves 28r' and 28ℓ' have the same structure as the on-off valves 28ℓ and 28r in the previous embodiments, i.e., a structure with rectangular valve members 31ℓ' and 31r' secured by machine screws 32' to valve stem 30ℓ' and 30r' extending through the valve bores 27ℓ' and 27r' made in the valve units 22ℓ' and 22r'. According to this embodiment, the on-off valves 28ℓ' and 28r' are closed in a lower speed operation region of the engine, so that the left and right resonance passages 25ℓ' and 25r' are put into communication through their entire lengths with the left and right resonance chambers Cr-ℓ and Cr-r. This establishes a resonance supercharge intake system having an increased passage length and a lower natural frequency to increase the volume efficiency in a lower speed rotation region. When the engine has been brought into a higher speed operation, the actuator 29 is operated to open the left and right on-off valves 28ℓ' and 28r', so that the left and right resonance chambers Cr-ℓ and Cr-r and the resonance passages 25ℓ' and 25r' which have been hitherto in communication with each other through the inlet ports 26ℓ' and 26r' are short-circuited through the valve bores 27ℓ' and 27r' to reduce the substantial length of the resonance passages 25ℓ' and 25r', and the resonance passages 25ℓ' and 25r' serve as portions of the resonance chambers Cr-ℓ and Cr-r to increase the substantial volume of the chambers Cr-ℓ and Cr-r and enhance the volume efficiency in the higher speed rotation region. Also in the third embodiment, it is possible to simplify and reduce the size of the structure of the intake system by virtue of a reasonable layout of the resonance passages 25ℓ' and 25r', the resonance chambers Cr-ℓ and Cr-r the valve units 22ℓ' and 22r' and the on-off valves 28ℓ' and 28r'. Figs. 9 to 13 illustrate a fourth embodiment of the present invention. In this embodiment, an intake system In is disposed within a V-space C between left and right cylinder blocks 1ℓ and 1r 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 including a pair of left and right resonance chambers Cr-ℓ and Cr-r, and an intake manifold Mi joined to that end faces of the left and right cylinder blocks 1ℓ and 1r to which intake ports 8 are opened, thereby permitting the communication between the left and right resonance chambers Cr-ℓ and Cr-r and the left and right cylinder groups Cr and Cℓ. The passage Pi is constructed with a throttle body 15 integrally connected to a downstream end of an intake pipe 14 connected to the air cleaner Ac, as shown in Fig. 10. The intake pipe 14 is formed into a hollow cylindrical shape so that intake gas may be drawn there into from the air cleaner Ac. The throttle body 15 is bifurcated into left and right branch passages 18ℓ and 18r at a position downstream of 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 means 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. 12 and 13 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 the intake nanifold 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. 10 to 13 that the interior of 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 a communication passage located between the left and right resonance passages 25ℓ and 25r by two partition walls 24ℓ and 24r extending in a direction of a crankshaft 6 of an engine, i.e., in a direction of a flow of 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 interior of 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 24s 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, 27ℓ and 27r, 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 bores 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 the 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 3lℓ and 31r 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 bores 27s and adapted to be rotatably driven by another actuator 33, and a rectangular plate-like valve member 31s provided in each valve bore 27s is secured to the valve stem 30s by machine screws 32. The two actuators 29 and 33 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 outlet ports 34ℓ and 34r are opened at upper walls of the left and right resonance chambers Cr-ℓ and Cr-r along their longitudinal axes. The three outlet 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 outlet 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 fourth 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, all the on-off valves 28ℓ, 28r and 28s are controlled to be closed as shown by a solid line in Figs. 10 to 13 to close their valve bores 27ℓ, 27r and 27s, so that 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 with the left and right resonance chambers Cr-ℓ and Cr-r via valves 28ℓ, 28r is also cut off. In this state, there are established two series of intake systems for each cylinder group, which are each comprised of the branch passage 18ℓ, 18r, the resonance passage 25ℓ, 25r, left or right resonance chamber Cr-ℓ, Cr-r, and left or right distributor pipes 35₁, 35₂, 35₃, 35₄, 35₅ and 35₆ ie. 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 accomplished 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 niddle 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 heen 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 accomplished 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. 20 and 21, 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 in which a negative pressure wave produced in an intake stroke of the engine is reflected and turned in the larger volume inertia supercharge distributing chamber Ch and a positive pressure wave is 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 accomplishing 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 connecting and disconnecting the left and right resonance chambers Cr-ℓ and Cr-r with and from each other or with and from the resonance passages 25ℓ and 25r provided in the resonance assembly box Bg 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 engine 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, and since the left and right resonance chambers Cr-ℓ and Cr-r are defined in the upper assembly box portion 21₂, the pair of resonance passages 25ℓ and 25r and the communication chamber Cs are defined in the lower assembly box portion 21₁ and the inlet ports 26ℓ and 26r and the on-off valves 28ℓ, 28r and 28s are 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. In the fourth embodiment, the duties of the upper and lower assembly box portions 21₁ and 21₂ may be 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.

Claims: An intake device for a multi-cylinder internal combustion engine, said engine being V-shaped and including a pair of engine blocks (Bl,Br) defining a V-space therebetween, cylinders (3l,3r) being provided in the respective engine blocks (Bl,Br) and having 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 engine block (Bl,Br), said intake device comprising: a pair of resonance chambers (Cr-l, Cr-r) which communicate with the cylinders (3l,3r) of the respective engine blocks (Bl,Br); and a pair of resonance passages (18l,18r; 25l, 25r; 25l',25r') which communicate at downstream sides thereof with said pair of resonance chambers (Cr-l, Cr-r), respectively, and at upstream sides thereof with the atmosphere via a throttle valve (20), the resonance chambers (Cr-l, Cr-r) and the resonance passages (18l,18r; 25l,25r; 25l',25r') each being formed of a substantially tubular configuration elongated to extend parallel to the crankshaft (6) of the engine and being adjacent to one another; characterised in that at least one of the resonance chambers and the associated resonance passage communicating therewith are separated from one another by a partition wall (24₂,24₃; 24₅; 24; 24'; 24s,24l,24r), and in that at least one on-off valve (25;25'; 28l,28r; 28l₁,28l₂,28r₁, 28r₂; 28l',28r'; 28s) is provided in said partition wall for providing connection and disconnection between the said resonance chamber and its associated resonance passage, thereby changing the intake characteristics 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 (21₂) and lower (21₁) assembly box portions for separating their opened surfaces, said resonance chambers (Cr-l, Cr-r) being formed in one of the assembly box portions (21₁,21₂) and said resonance passages (25l,25r) being formed in the other of the assembly box portions, said valve unit (22) including said at least one on-off valve for changing the intake characteristic of the engine. The intake device according to claim 1, or 2 wherein said on-off valve (25; 28l,28r; 28l₁,28l₂,28r₁, 28r₂; 28l',28r') serves to change the length of the resonance passages (18l,18r; 25l,25r; 25l',25r') through opening and closing operations thereof. The intake device according to claim 1 or 2, wherein said on-off valve (25'; 28s) serves to connect said pair of resonance chambers (Cr-l, Cr-r) with each other. The intake device according to claim 1, wherein as said on-off valve there are provided an on-off valve (28l,28r) for changing the length of the resonance passages (25l,25r) through opening and closing operations thereof and another on-off valve (28s) for connection and disconnection between the resonance chambers (Cr-l, Cr-r). The intake device according to claim 2, wherein as said on-off valve there are provided an on-off valve (28l,28r) for changing the length of the resonance passages (25l,25r) through opening and closing operations thereof and another on-off valve (28s) for connection and disconnection between the resonance chambers (Cr-l, Cr-r), these on-off valves being located in a plane which is defined by said valve unit (22). The intake device according to claim 1, wherein said resonance passages (18l,18r; 25l,25r; 25l',25r') each communicate at their longitudinal one end with the associated resonance chamber (Cr-l, Cr-r) and as said on-off valve an on-off valve (25; 28l,28r; 28l₁,28l₂, 28r₁,28r₂; 28l',28r') is provided at the partition wall for connection between the resonance passage and associated resonance chamber at a location remote from said longitudinal end toward the other longitudinal end.

Inventors: ASAKI YASUAKI C O K K HONDA GI, HIRATANI MASAAKI C O K K HONDA, KITAMI YASUO C O K K HONDA GIJ, ASAKI, YASUAKI, C/O K.K. HONDA GIJUTSU KENKYSHO, HIRATANI, MASAAKI, C/O K.K. HONDA GIJUTSU KENKYSHO, KITAMI, YASUO, C/O K.K. HONDA GIJUTSU KENKYSHO
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 1990
Main classification: F02B27
IPC codes: F02B75, F02B27