JP2013044236A - Intake and exhaust device for multi-cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intake and exhaust device for a multi-cylinder engine that can improve engine torque and fuel economy performance with a simple configuration.SOLUTION: The intake and exhaust device for the multi-cylinder engine includes a throttle part 53 interposed between independent exhaust passages 52 and a collecting part 58, and switching means 56, 56b, 56c capable of switching the state of the throttle part 53 into an independent flow state of partitioning the throttle part into a plurality of gas passing spaces 57 individually communicating with the respective independent exhaust passages 52, and a communicating state in which the gas passing spaces 57 communicate with one another. The gas passing spaces 57 are shaped to be smaller in passage area downstream than upstream. In a first operating region A1 including a low-speed high-load region, the valve opening period of an intake valve 19 and that of an exhaust valve 20 overlap with each other, exhaust valves 20 of other cylinders are opened during an overlap period, and the spaces in the throttle part 53 are placed in the independent flow state. In a second operating region A2 including a high-speed high-load region, the spaces in the throttle part 53 are placed in the communicating state.

Description

  The present invention relates to intake and exhaust of a multi-cylinder engine having a plurality of cylinders each having an intake port and an exhaust port and provided with an intake valve capable of opening and closing the intake port and an exhaust valve capable of opening and closing the exhaust port. Relates to the device.

  2. Description of the Related Art Conventionally, an intake / exhaust device has been developed for the purpose of increasing engine torque in an engine such as an automobile.

  For example, Patent Document 1 is a device having a turbocharger, which is connected to an exhaust port of each cylinder and independent from each other, and an independent passage provided upstream of the turbocharger. Are provided, and a valve provided in the collecting portion and capable of changing the flow area of each independent passage is disclosed. In this apparatus, the flow area of the independent exhaust passage is reduced by the valve, so that the exhaust of the cylinder in the exhaust stroke flows from the predetermined independent passage into the collecting portion at a relatively high speed. The amount of gas supplied to the turbocharger is reduced by sucking the exhaust gas in the other independent passage downstream by the so-called ejector effect that causes the negative pressure generated in the surrounding area to act on the other independent passage in the collecting portion. The engine torque is increased to increase the engine torque.

JP 2009-97335 A

  In engines such as automobiles, there is still a high demand for improvement of engine torque and the like, and it is required to further increase engine torque with a simple configuration.

  In view of such circumstances, an object of the present invention is to provide an intake / exhaust device for a multi-cylinder engine that can increase intake efficiency with a simple configuration and thereby increase engine torque.

  In order to solve the above problems, the present invention provides a plurality of cylinders each having an intake port and an exhaust port and provided with an intake valve capable of opening and closing the intake port and an exhaust valve capable of opening and closing the exhaust port. And an independent exhaust passage that is connected to exhaust ports of one cylinder or a plurality of cylinders whose exhaust sequences are not continuous with each other and through which the exhaust passes, and each of the independent exhaust passages Provided on the downstream side of the exhaust gas, and the exhaust gas passing through the independent exhaust passages is gathered inside, and is interposed between the independent exhaust passages and the collective portion, and the inner side of the independent exhaust gas. A throttle part through which the exhaust discharged from the passage passes, and each independent exhaust passage so that the exhaust discharged from each independent exhaust passage passes through the throttle part independently of each other. The state of the restrictor is divided into an independent flow state that divides a space in the restrictor into a plurality of gas passage spaces that pass therethrough, and a communication state in which the gas pass spaces corresponding to the independent exhaust passages communicate with each other. Switching means, valve driving means capable of driving the intake valve and exhaust valve of each cylinder, and control means capable of controlling the switching means and the valve driving means, each gas passage space In the independent flow state, the exhaust gas is discharged from the exhaust port of each cylinder through the independent exhaust passage and the gas passage space to the collecting portion, and adjacent to the gas passage space and the gas passage space. The flow area on the downstream side is smaller than the flow area on the upstream side so that a negative pressure is generated by the ejector effect in the exhaust port connected to the communicating independent exhaust passage. The gas passage spaces corresponding to the independent exhaust passages connected to the cylinders in which the exhaust order is continuous are arranged adjacent to each other, and the control means sets the engine speed in advance. In the first operation region including at least a low speed and high load region in which the engine load is lower than the predetermined reference speed and higher than a predetermined load set in advance, the intake valve opening period and the exhaust valve opening of each cylinder are set. The valve period overlaps with a predetermined overlap period, and the overlap period of one cylinder overlaps with the time when the exhaust valve of the other cylinder is opened between the cylinders in which the exhaust order continues. While the valve driving means drives the intake valve and the exhaust valve of each cylinder, the switching means changes the state of the throttle portion to the independent flow state. In the second operation region including at least a high-speed and high-load region where the engine speed is higher than the reference speed and the engine load is higher than a predetermined load set in advance, the state of the throttle unit is changed by the switching means. Provided is an intake / exhaust device for a multi-cylinder engine that is in a communicating state.

  According to the present invention, scavenging in the cylinder can be promoted by effectively using the ejector effect in the first operation region including the low speed and high load region, and exhaust is performed in the second operation region including the high speed and high load region. The resistance can be kept small, and the intake torque can be increased and the engine torque can be increased in a wider operating range.

  Specifically, in this configuration, in the first operation region, the overlap period of a predetermined cylinder and the timing when the exhaust valves of other cylinders are opened overlap each other, and each independent The exhaust passage is individually configured to communicate with each gas passage space in the throttle portion. Then, in the state in the first operation region, as the exhaust gas is discharged from the predetermined cylinder in the exhaust stroke to each gas passage space, the other adjacent gas passage space and the exhaust port (described above) connected to this gas passage space The flow passage area of each gas passage space is set to be smaller on the downstream side than on the upstream side so that a negative pressure is generated by the ejector effect in the exhaust port during the overlap period. Therefore, in the first operating region, negative pressure due to the ejector effect can be applied to the exhaust port of the cylinder in the overlap period, so that more residual gas in the cylinder can be sucked out to the exhaust port side, and scavenging performance is improved. Can do. As the scavenging performance is improved, an increase in intake efficiency and a suppression of knocking associated with a reduction in residual gas can be realized, and a high engine torque can be obtained.

  Here, each gas passage space has a shape in which the flow area is smaller on the downstream side than on the upstream side, that is, a throttle shape so that a high ejector effect is exhibited. For this reason, when the engine speed and load increase and the exhaust flow rate increases, the exhaust resistance increases and the scavenging performance may be deteriorated. On the other hand, in this configuration, in the second operation region including the high-speed and high-load region, the gas passage spaces communicate with each other, and the exhaust gas discharged from the independent exhaust passage has a larger flow area in the throttle portion. It is switched to pass. Therefore, it is possible to suppress the exhaust resistance that increases in the second operation region, reduce the exhaust pumping loss, and increase the intake efficiency. Also in this second operation region, high engine torque and high thermal efficiency, that is, fuel efficiency performance. Can be obtained.

  In the present invention, the second operating region includes a high speed region in which the engine speed is higher than the reference speed and a low speed excluding the low speed and high load region in a region in which the engine speed is lower than the reference speed. It is preferable to include a low load region (claim 2).

  In this way, excessive scavenging can be suppressed in the low-speed and low-load region to secure the residual gas amount in the cylinder, thereby reducing the pumping loss and cooling loss of the intake air, and high thermal efficiency and consequently high fuel efficiency. Performance can be obtained. Specifically, in the low-speed and low-load region, the intake pressure is low and the in-cylinder gas amount is small. Therefore, when high scavenging is performed due to the ejector effect, the pumping of intake air that occurs due to the decrease in the residual gas amount in the cylinder The influence of the increase in the loss of cooling and the increase in the cooling loss due to the increase in the combustion temperature is increased, and the thermal efficiency may be deteriorated. On the other hand, if the passage area through which the gas passes is increased by communicating with the gas passage space in the low-speed and low-load region as in this configuration, the exhaust speed is kept low and the negative pressure generated around is reduced. As a result, it is possible to suppress the excessive ejector effect, and thus excessive scavenging, and to secure the residual gas amount in the cylinder.

  Further, according to this configuration, it is possible to obtain high thermal efficiency while suppressing exhaust resistance in the entire high speed region.

  In the present invention, the independent exhaust passage and three or more gas passage spaces corresponding to the independent exhaust passage are provided, and the throttle portion has a shape in which all the gas passage spaces communicate with each other in the communication state. It is preferable to have (claim 3).

  In this way, in the second operation region, it is possible to further increase the flow path area of the region through which the exhaust discharged from each independent exhaust passage passes in the throttle portion. Thus, exhaust resistance can be suppressed, and excessive scavenging due to the ejector effect can be suppressed.

  Further, in the present invention, a partition wall capable of partitioning the space in the throttle unit is provided in the throttle unit, and the switching unit is located at a position where the plurality of gas passage spaces are partitioned in the throttle unit. It is preferable that the space in the throttle portion is placed in the independent circulation state by disposing the partition wall, and the space in the throttle portion is brought into the communication state by shifting the partition wall from the position in the independent circulation state by a predetermined amount. Item 4).

  If it does in this way, the state of the space in an aperture | diaphragm | squeeze part can be easily switched by the simple structure of changing the position of a partition.

  In the above configuration, the independent exhaust passages and the gas passage spaces are arranged substantially on a circumference, and the partition wall is a center extending in the upstream / downstream direction through the center of the circumference where the gas passage spaces are arranged. It is preferable that the shaft extends radially outward from the shaft, and the switching unit rotates the partition wall around the central axis.

  In this way, the partition wall extends in the upstream / downstream direction, that is, the exhaust flow direction in both the independent flow state and the communication state, and the partition wall prevents the exhaust flow from being inhibited in either state. It can be avoided.

  In the above-described configuration, the second operation region includes a high speed region where the engine speed is higher than the reference speed and a low speed excluding the low speed and high load region among regions where the engine speed is lower than the reference speed. A low load area, and the control means causes the switching means to switch the partition wall as the engine speed is higher than the low speed and high load area or as the engine load is lower than the low speed and high load area. It is preferable to increase the amount of rotation of the above (claim 6).

  In this configuration, in the communication state, the amount of the exhaust discharged from the independent exhaust passage so as to be directed to the other gas passage space side by the partition wall increases as the engine speed increases and the engine load decreases. Is done. Therefore, the exhaust resistance can be appropriately suppressed according to the exhaust flow rate that increases as the engine speed increases.

  In this way, excessive scavenging can be suppressed in the low-speed and low-load region to secure the residual gas amount in the cylinder, thereby reducing the pumping loss and cooling loss of the intake air, and high thermal efficiency and consequently high fuel efficiency. In addition to being able to obtain performance, it is possible to obtain high thermal efficiency by reducing the exhaust resistance in the entire high-speed region. Further, in this configuration, the amount of exhaust that is divided by the partition toward the other gas passage space side among the exhaust discharged from the independent exhaust passage is higher as the engine speed is higher than the low-speed high-load region, Alternatively, it is increased as the engine load is lower than in the low-speed and high-load region. Therefore, the exhaust resistance can be appropriately suppressed according to the exhaust flow rate that increases as the engine speed increases, and the residual gas amount that increases from the viewpoint of improving thermal efficiency as the engine load decreases. Accordingly, excessive scavenging can be appropriately suppressed, and engine torque and fuel consumption performance can be further improved in the entire operation region.

  Here, as described above, in the present invention, the flow path area of the space through which the exhaust discharged from the independent exhaust passage passes is changed by changing the state of the space in the throttle portion. Therefore, for example, in order to change the flow path area, the structure of the exhaust system extending from the engine body is simplified compared to the case where a passage having a large flow path area is provided separately from the throttle portion, and the length of the exhaust system is reduced. Can be shortened. Therefore, in the present invention, if it has a catalyst device that can purify the exhaust discharged from each cylinder, and the catalyst device is directly connected to the downstream end of the collecting portion, from the engine body to the catalyst device By shortening the distance, the temperature of the exhaust gas flowing into the catalyst device can be increased (claim 6). That is, according to this configuration, the temperature of the exhaust gas flowing into the catalyst device can be increased, and the scavenging activation or the activity maintenance of the catalyst device can be promoted.

  As described above, according to the present invention, the intake efficiency can be increased in a wider operating range.

1 is a schematic configuration diagram of an intake / exhaust device for a multi-cylinder engine according to an embodiment of the present invention. It is a schematic side view of FIG. It is a block diagram for demonstrating the control system of the intake / exhaust apparatus of the multicylinder engine which concerns on embodiment of this invention. It is a figure for demonstrating the valve opening timing and valve closing timing of an intake valve and an exhaust valve in the intake / exhaust apparatus of the multicylinder engine which concerns on embodiment of this invention. It is the VV sectional view taken on the line of FIG. It is sectional drawing which expanded and showed the narrowing part and gathering part vicinity in an independent distribution state. It is the figure of the cut surface which cut | disconnected FIG. 6 by the VII-VII line. It is the figure of the cut surface which cut | disconnected FIG. 6 by the VIII-VIII line. It is the figure which showed the mode inside the aperture | diaphragm | squeeze part in FIG. It is sectional drawing which expanded and showed the aperture | diaphragm | squeeze part and the gathering part vicinity in a communication state. It is the figure of the cut surface which cut | disconnected FIG. 10 by the XI-XI line. It is the figure of the cut surface which cut | disconnected FIG. 10 by the XII-XII line. It is the figure which showed the mode inside the aperture | diaphragm | squeeze part in FIG. It is the figure which removed the partition from FIG. 7, Comprising: It is the figure which looked at the upstream end of the aperture | diaphragm | squeeze part main body from the upstream. It is the figure which removed the partition from FIG. 8, Comprising: It is the figure which looked at the downstream end of the aperture | diaphragm | squeeze part main body from the downstream. It is the figure which showed the control map used with the intake / exhaust apparatus of the multicylinder engine which concerns on embodiment of this invention. It is a figure for demonstrating the valve timing of an intake valve and an exhaust valve. It is the figure which showed the control map used with the intake / exhaust apparatus of the multicylinder engine which concerns on other embodiment of this invention. FIG. 8 is a view corresponding to FIG. 7 in an intake / exhaust device for a multi-cylinder engine according to another embodiment of the invention. FIG. 9 is a view corresponding to FIG. 8 in an intake / exhaust device for a multi-cylinder engine according to another embodiment of the invention.

(1) Overall Configuration of Device FIG. 1 is a schematic configuration diagram of an intake / exhaust device 100 for a multi-cylinder engine according to a first embodiment of the present invention. FIG. 2 is a schematic side view of FIG. The apparatus 100 includes an engine body 1 having a cylinder head 9 and a cylinder block 10 (see FIG. 2), an ECU (control means, see FIG. 3) 90, an exhaust manifold 50 connected to the engine body 1, and an exhaust manifold. 50 and a catalytic device 60 connected to 50.

  A plurality of cylinders 12 into which pistons are respectively inserted are formed in the cylinder head 9 and the cylinder block 10. In the present embodiment, the engine body 1 is an in-line four-cylinder engine, and is formed in a state where four cylinders 12 are arranged in series inside the cylinder head 9 and the cylinder block 10. Specifically, a first cylinder 12a, a second cylinder 12b, a third cylinder 12c, and a fourth cylinder 12d are formed in order from the right in FIG. Each cylinder head 9 is provided with a spark plug 15 so as to face a combustion chamber partitioned above the piston.

  The engine body 1 is a four-cycle engine. As shown in FIG. 4, in each of the cylinders 12 a to 12 d, ignition is performed by the spark plug 15 at a timing shifted by 180 ° C., and the intake stroke, the compression stroke, The expansion stroke and the exhaust stroke are each shifted by 180 ° C. In the present embodiment, ignition is performed in the order of the first cylinder 12a → the third cylinder 12c → the fourth cylinder 12d → the second cylinder 12b, and the exhaust stroke and the like are performed in this order.

  The cylinder head 9 is provided with two intake ports 17 and two exhaust ports 18 each opening toward the combustion chamber. The intake port 17 is for introducing intake air into each cylinder 12. The exhaust port 18 is for exhausting the exhaust from each cylinder 12. Each intake port 17 is provided with an intake valve 19 for opening and closing the intake port 17 to communicate or block the intake port 17 and the inside of the cylinder 12. Each exhaust port 18 is provided with an exhaust valve 20 for opening and closing these exhaust ports 18 to communicate or block these exhaust ports 18 and the inside of the cylinder 12. The intake valve 19 is driven by an intake valve drive mechanism (valve drive means) 30 to open and close the intake port 17 at a predetermined timing. The exhaust valve 20 is driven by an exhaust valve drive mechanism (valve drive means) 40 to open and close the exhaust port 18 at a predetermined timing.

  The intake valve drive mechanism 30 has an intake camshaft 31 and an intake VVT 32 connected to the intake valve 19. The intake camshaft 31 is connected to the crankshaft via a known power transmission mechanism such as a chain / sprocket mechanism, and rotates with the rotation of the crankshaft to drive the intake valve 19 to open and close.

  The intake VVT 32 is for changing the valve timing of the intake valve 19. The intake VVT 32 is arranged coaxially with the intake camshaft 31 and changes the phase difference between a predetermined driven shaft that is directly driven by the crankshaft and the intake camshaft 31, thereby the crankshaft and the intake air The valve timing of the intake valve 19 is changed by changing the phase difference from the camshaft 31. As a specific configuration of the intake VVT 32, for example, a plurality of liquid chambers arranged in the circumferential direction are provided between the driven shaft and the intake camshaft 31, and a pressure difference is provided between the liquid chambers to thereby change the position. A hydraulic mechanism that changes the phase difference, an electromagnetic mechanism that has an electromagnet provided between the driven shaft and the intake camshaft 31, and changes the phase difference by applying electric power to the electromagnet, etc. Is mentioned. The intake VVT 32 changes the phase difference based on the target valve timing of the intake valve 19 calculated by the ECU 90.

  The exhaust valve drive mechanism 40 has the same structure as the intake valve drive mechanism 30. That is, the exhaust valve drive mechanism 40 changes the valve timing of the exhaust valve 20 by changing the phase difference between the exhaust camshaft 41 and the crankshaft, and the exhaust camshaft 41 connected to the exhaust valve 20 and the crankshaft. And an exhaust VVT 42 to be used. The exhaust VVT 42 changes the phase difference based on the target valve timing of the exhaust valve 20 calculated by the ECU 90. The exhaust camshaft 41 rotates with the rotation of the crankshaft under this phase difference to drive the exhaust valve 20 to open and close at the target valve timing.

  In the present embodiment, the intake VVT 32 and the exhaust VVT 42 open the intake valve 19 and the exhaust valve 20 while keeping the valve opening period and the lift amount, that is, the valve profile, of the intake valve 19 and the exhaust valve 20 constant, respectively. Change the timing and valve closing timing respectively.

(2) Configuration of Exhaust System Details of the exhaust system including the exhaust manifold 50 and the catalyst device 60 will be described next. The exhaust manifold 50 includes, in order from the upstream side, three independent exhaust passages 52, a throttle portion 53, and a substantially cylindrical gathering portion 58.

(2-1) Configuration of Independent Exhaust Passage 52 As shown in FIG. 1, each independent exhaust passage 52 is connected to the exhaust port 18 of each cylinder 12 formed in the cylinder head 9. Specifically, in the cylinder 12, the exhaust port 18 of the first cylinder 12a and the exhaust port 18 of the fourth cylinder 12d are individually connected to the independent exhaust passages 52 and 52, respectively. On the other hand, the exhaust ports 18 of the second cylinder 12b and the third cylinder 12c, whose exhaust strokes are not adjacent to each other and the exhaust order is not continuous, are not exhausted from these cylinders 12b, 2c at the same time, thus simplifying the structure. From this point of view, it is connected to one independent exhaust passage 52 formed in a bifurcated shape. Specifically, the independent exhaust passage 52 connected to the exhaust ports 18 of the second cylinder 12b and the third cylinder 12c is separated into two passages on the upstream side, and one of the second cylinders 12b is connected to one of them. The exhaust port 18 is connected, and the exhaust port 18 of the third cylinder 12c is connected to the other.

  In the present embodiment, the independent exhaust passage 52 corresponding to the exhaust port 18 of the second cylinder 12b and the third cylinder 12c is linearly opposed to the intermediate position between the cylinders 12b and 12c, that is, the substantially central portion of the engine body 1. The independent exhaust passages 52 that extend and correspond to the exhaust ports 18 of the other cylinders 12a and 12d are independent exhaust passages that correspond to the second cylinder 12b and the third cylinder 12c from positions corresponding to the corresponding exhaust ports 18. Curved and extended toward 52. As shown in FIG. 2, each independent exhaust passage 52 extends from the cylinder head 9 in the horizontal direction and then extends obliquely downward and rearward in the vehicle front-rear direction.

  5 is a cross-sectional view taken along line VV in FIG. As shown in FIG. 5, the sectional shape of the downstream end 52a of the independent exhaust passage 52, that is, the opening shape of the downstream end 52a is circular, and the circular downstream end 52a has an axis extending obliquely downward rearward. They are arranged at equal intervals on a circumferential surface centered on the point O1 on L.

(2-2) Configuration of Restriction Unit 53 As shown in FIG. 2 and the like, the restriction unit 53 extends rearward and obliquely downward along the downstream end portion of the independent exhaust passage 52.

  FIG. 6 is an enlarged cross-sectional view showing the vicinity of the narrowed portion 53 and the gathering portion 58 in an independent distribution state to be described later. FIG. 7 is a view of the cut surface of FIG. 6 cut along the line VII-VII, and is a view of the upstream end of the throttle portion 53 in the independent flow state as viewed from the upstream side. FIG. 8 is a view of the cut surface of FIG. 6 cut along the line VIII-VIII, and is a view of the downstream end of the throttle portion 53 in the independent flow state as viewed from the downstream side. FIG. 9 is a perspective view showing a part of the inside of the throttle portion 53 in the independent circulation state shown in FIG.

  FIG. 10 is a view corresponding to FIG. 6 and is an enlarged cross-sectional view showing the vicinity of the throttle portion 53 and the gathering portion 58 in a communication state to be described later. FIG. 11 is a view of the cut surface of FIG. 10 cut along the line XI-XI, and is a view of the upstream end of the throttle portion 53 in the communication state as viewed from the upstream side. FIG. 12 is a cross-sectional view of FIG. 10 taken along the line XII-XII, and is a view of the downstream end of the throttle portion 53 in the communication state as viewed from the downstream side. FIG. 13 is a perspective view showing a part of the inside of the throttle portion 53 in the communication state shown in FIG.

  7, 8, 11, and 12, the exhaust can pass through so that the position of the throttle body 54, the partition wall 55, and the space through which the exhaust can pass becomes clearer. The space is shown in black.

  The throttle unit 53 includes a main body 54 and a plurality of partition walls 56. The main body 54 of the throttle portion 53 is a cylindrical member having the axis L as a central axis, and a space through which the exhaust discharged from each independent exhaust passage 52 passes is formed inside thereof. Each partition wall 56 is a member that can partition the inside of the throttle body 54 into a plurality of spaces.

  FIG. 14 is a view in which the partition wall 56 is removed from FIG. 7 and is a view of the upstream end of the throttle body 54 viewed from the upstream side. FIG. 15 is a view in which the partition wall 56 is removed from FIG. 8, and is a view of the downstream end of the throttle portion main body 54 as viewed from the downstream side.

  As shown in FIG. 14 and the like, the opening 54a at the upstream end of the throttle body 54 has three first virtual circles 201 arranged at equal intervals on a circumference centered on a point O2 on the central axis L. (Indicated by a chain line in FIG. 14) and a portion between these first virtual circles 201. The portion between the first virtual circles 201 forms part of the second virtual circle 202 passing through the vicinity of the center of each of the three first virtual circles 201 with the point O2 as the center, and the upstream end of the throttle body 54 The opening 54a has a three-leaf shape that bulges radially outward from three circular arcs arranged at equal intervals on the circumference of the second virtual circle 202. The first virtual circles 201 do not overlap each other, and the diameter of the second virtual circle 202 is slightly larger than the diameter of the first virtual circle 201.

  On the other hand, as shown in FIG. 15 and the like, the opening 54b at the downstream end of the throttle unit main body 54 has a circular shape centered on the point O3 on the axis L, and the throttle unit main body 54 has a corresponding shape. The opening edge at the downstream end has a circular ring shape. The diameter of the opening 54b at the downstream end of the throttle unit main body 54 is set to be the same as the diameter of the second virtual circle 202, and the downstream end opening 54b of the throttle unit main body 54 and the second virtual circle are viewed from the upstream and downstream directions. The circle 202 matches.

  Thus, the opening 54b at the downstream end of the throttle unit main body 54 is smaller than the opening 54a at the upstream end of the throttle unit main body 54, and the flow path area of the inner space of the throttle unit main body 54 is reduced toward the downstream. Yes.

  Specifically, from the three arc portions forming part of the circumference of the second imaginary circle 202 in the opening edge of the upstream end of the throttle body 54, surfaces parallel to the central axis L respectively toward the downstream side. 55a (hereinafter referred to as a straight surface) extends. As described above, the second virtual circle 202 and the opening 54b at the downstream end of the throttle body 54 have the same circular shape, and each straight surface 55a has the circumference of the second virtual circle 202 and the downstream of the throttle body 54. A part of the cylindrical surface of the virtual cylinder extending between the end opening edges is formed.

  On the other hand, from the opening edge at the upstream end of the throttle body 54, the surfaces that incline in the direction approaching the central axis L from the three arc portions forming part of the circumference of the first virtual circle 201 toward the downstream side. 55b (hereinafter, this portion is referred to as a reduced diameter surface) extends.

  The inner peripheral surface of the throttle portion main body 54 is constituted by the straight surface 55a and the diameter-reduced surface 55b, and each cross section of the throttle portion main body 54, that is, the flow path area, is reduced toward the downstream.

  Each first virtual circle 201 is set to have the same shape as the opening of the circular downstream end 52 a of each independent exhaust passage 52. The throttle body 54 is connected to the downstream end 52a of each independent exhaust passage 52 at a position where each first virtual circle 201 matches the opening of the downstream end 52a of each independent exhaust passage 52.

  The partition wall 56 is a plate-like member extending in the upstream / downstream direction with a constant cross-sectional shape. The cross section of the partition wall 56 has the same shape as the portion excluding the three first virtual circles 201 from the opening 54 a at the upstream end of the throttle body 54. As shown in FIGS. 7 to 9, the partition wall 56 is arranged at the upstream end thereof at a portion excluding the three first virtual circles 201 in the opening 54 a at the upstream end of the throttle body 54. The space in the part main body 54 is partitioned into three gas passage spaces 57 extending downstream from these three first virtual circles 201.

  Specifically, the partition wall 56 includes three partition walls 56a formed integrally with each other and extending in the upstream / downstream direction. Each partition wall 56a extends radially from the central axis L toward each straight surface 55a. The radial length of each partition wall 56 a matches the radius of the second virtual circle 202, and the radial front end portion (hereinafter simply referred to as the front end portion) 56 a </ b> _ 1 of each partition wall 56 a is the second virtual circle 202. A part of the cylindrical surface of the virtual cylinder extending between the circumference and the opening edge of the downstream end of the throttle body 54 is configured. Therefore, in a state where each partition wall 56a is disposed at the position shown in FIGS. 6 to 9 (hereinafter referred to as a partition position), the tip portion 56a_1 of each partition wall 56a is a surface over the straight surface 55a and the entire upstream and downstream direction. Contact.

  Of the outer peripheral surface of the partition wall 56a, a portion 56a_2 extending between the front end portions 56a_1 has a shape constituting a part of a virtual cylindrical surface extending downstream from the circumference of the first virtual circle 201 in parallel with the central axis L. ing. Therefore, the opening 54a at the upstream end of the throttle body 54 is shown in FIG. 7 in a state where the partition walls 56a are arranged at the partition positions and the front end portions 56a_1 of the partition walls 56a are in surface contact with the straight surface 55a. In addition, the partition wall 56a is divided into three regions consisting of the first virtual circle 201, and the opening 54b at the downstream end of the throttle body 54, as shown in FIG. It is divided into three fan-shaped regions. The space in the throttle body 54 is partitioned into three gas passage spaces 57 whose flow area decreases from the first virtual circle 201 region at the upstream end toward the fan-shaped region at the downstream end. That is, three passages that do not communicate with each other are formed in the throttle body 54 with the reduced diameter surface 55b and the outer peripheral surface 56a_2 of the partition wall 56a as the inner peripheral surface. Hereinafter, a state in which the partition wall 56a is in the partition position and three passages that do not communicate with each other are formed in the throttle body 54 is referred to as an independent circulation state.

  As described above, each first virtual circle 201 and the opening of the downstream end 52a of each independent exhaust passage 52 coincide with each other. Therefore, in the independent circulation state, the exhaust discharged from each independent exhaust passage 52 individually flows into the three gas passage spaces 57. Specifically, the exhaust gas discharged from the second cylinder 12b or the third cylinder 12c, the exhaust gas discharged from the first cylinder 12a, and the exhaust gas discharged from the fourth cylinder 12d respectively correspond to gas passage spaces. It flows into 57 individually. Further, as described above, each gas passage space 57 has a shape that decreases as the flow path area goes downstream. Therefore, in the independent circulation state, the exhaust gas discharged from each independent exhaust passage 52 is increased in speed by passing through each gas passage space 57 and flows into the collecting portion 58 at a high speed.

  A rotation shaft 56b (see FIGS. 1 and 9) extending along the central axis L is connected to the partition wall 56. The rotating shaft 56 b extends from the upstream end of the partition wall 56 to the upstream side, and the tip thereof is exposed outside the throttle portion 53 and the independent exhaust passage 52. A rotation actuator 56c (see FIGS. 1 and 3) for rotating the rotation shaft 56b and the partition wall 56, that is, each partition wall 56a, is attached to the tip of the rotation shaft 56b. The rotation actuator 56c rotates the rotation shaft 56b and the partition walls 56a around the central axis L in response to a command from the ECU 90 described later. When each partition wall 56a is rotated from the partition position (the position in FIGS. 6 to 9 corresponding to the independent circulation state), the partition state in the throttle body 54 changes and is partitioned by each partition wall 56a. Each gas passage space 57 communicates with each other. Hereinafter, the state where the gas passage spaces 57 communicate with each other is referred to as a communication state.

  Specifically, as described above, the front end portion 56a_1 of each partition wall 56a is a cylindrical surface of a virtual cylinder extending between the circumference of the second virtual circle 202 and the opening edge of the downstream end of the throttle body 54. Part of it. Therefore, the tip end portion 56a_1 of each partition wall 56a is driven along the cylindrical surface of the virtual cylinder by being driven by the rotation actuator 56c. Therefore, when the front end portion 56a_1 of each partition wall 56a deviates from the partition position in surface contact with the straight surface 55a, the inner end of the front end portion 56a_1 of each partition wall 56a and the throttle portion main body 54 at the downstream end of the throttle portion main body 54. Contact with the peripheral surface (opening edge at the downstream end of the throttle body 54) is maintained. On the other hand, in this case, at the portion upstream of the downstream end of the throttle body 54, as shown in FIG. 11, the tip 56a_1 of each partition wall 56a is the inner peripheral surface (reduced diameter surface) of the throttle body 54. 55b), the contact between the tip 56a_1 and the inner peripheral surface 55b of the throttle body 54 is released. The three gas passage spaces 57 are partitioned into spaces that do not communicate with each other when the tip portion 56a_1 and the inner peripheral surface 55b of the throttle body 54 are in contact with each other. The passage spaces 57 communicate with each other.

  In the present embodiment, the rotation actuator 56c can rotate the rotation shaft 56b and the partition wall 56, that is, each partition wall 56a, by 60 degrees, and each partition wall 56a is defined as a partition position, as shown in FIG. The partition wall 56a extends from the central axis L toward the center of each gas passage space 57 and is rotated between positions where the three gas passage spaces 57 communicate with each other (hereinafter, this position is referred to as a communication position).

  As described above, when each partition wall 56a is rotated from the partition position to the communication position so that the gas passage spaces 57 communicate with each other and the state in the throttle portion 53 is brought into the communication state, the gas is discharged from each independent exhaust passage 52. After the exhaust gas flows into the corresponding gas passage space (gas passage space having an upstream end coinciding with the downstream end of the independent exhaust passage 52) 57, the exhaust gas also enters the other gas passage space 57 in addition to this gas passage space. Inflow. Therefore, the volume and flow path area of the space through which the exhaust discharged from each independent exhaust passage 52 passes in the inner space of the throttle body 54 is larger than in the independent circulation state. Accordingly, the exhaust gas passes through the throttle portion 53 in a state where the resistance is smaller than that in the independent circulation state.

  In particular, in the present embodiment, in a state where each partition wall 56a is in the communicating position, each partition wall 56a extends from the central axis L toward the central axis of each gas passage space 57, and each partition wall 56a and each gas A sufficient distance from the inner peripheral surface (the reduced diameter surface 55b) of the passage space 57 is secured. Therefore, a large amount of exhaust gas discharged from each independent exhaust passage 52 can flow into the gas passage space 57 side corresponding to the other independent exhaust passages 52, and the exhaust gas reliably passes through the throttle portion 53 in a state of low resistance. pass.

  Here, each partition wall 56a extends in the upstream / downstream direction, that is, in the exhaust flow direction, regardless of whether the partition wall 56a is located at the partition position or the communication position. Therefore, the partition wall 56a does not hinder the flow of exhaust gas, and the exhaust gas passes through the throttle body 54 with low resistance. Each partition wall 56a extends along a central axis L extending obliquely downward and rearward. For this reason, even when moisture contained in the exhaust gas adheres to the partition wall 56a, the moisture flows downstream, and corrosion of the partition wall 56a due to moisture is suppressed.

  As described above, in the present embodiment, the partition wall 56, the rotation shaft 56b, and the rotation actuator 56c allow the exhaust discharged from each independent exhaust passage 52 to pass through the throttle portion 53 independently of each other. As described above, there are independent flow states in which the space in the throttle portion 53 is divided into a plurality of gas passage spaces 57 individually communicating with the individual exhaust passages 52, and a plurality of gas passage spaces 57 corresponding to the individual exhaust passages 52. It functions as a switching means capable of switching the state of the throttle portion 53 to a communication state communicating with each other.

(2-3) Configuration of Aggregation Portion 58 The aggregation portion 58 is a portion where exhaust exhausted from each independent exhaust passage 52 and passing through the throttle portion 53 joins. As shown in FIGS. 1, 6, and 10, the collecting portion 58 includes a nozzle portion 58 a, a straight portion 58 b, and a diffuser portion 58 c in order from the upstream side.

  As described above, in the independent circulation state, the exhaust discharged from each independent exhaust passage 52 individually flows at a high speed through the gas passage space 57 and flows into the collecting portion 58. Therefore, in the independent flow state, a negative pressure is generated in the other gas passage space 57 adjacent to the gas passage space 57 from which the exhaust gas is discharged at a high speed due to the ejector effect.

  The nozzle portion 58a can obtain the ejector effect more effectively, and can be communicated with the other gas passage space 57 and the gas passage space 57 by the exhaust gas discharged from the predetermined independent exhaust passage 52 and the gas passage space 57. It has such a shape that a high negative pressure is generated in the exhaust port 18 to which the exhaust passage 52 is connected.

  Specifically, the nozzle portion 58a has a shape in which the flow passage area decreases toward the downstream side so that the exhaust discharged from each gas passage space 57 flows downstream while maintaining a high speed. In the present embodiment, the flow path area at the downstream end of the nozzle portion 58 a is set smaller than the total flow path area at the downstream end 52 a of each independent exhaust passage 52.

  Here, the diameter of a perfect circle having the same area as the flow path area at the downstream end of one gas passage space 57 and about 1/3 of the opening area at the downstream end of the throttle body 54 is represented by a (FIG. 6). And the diameter of a perfect circle having the same area as the flow path area at the downstream end of the nozzle portion 58a is D (see FIG. 6), a / D is set in a range of a / D ≧ 0.5. In this case, it has been found that the exhaust passes through the nozzle portion 58a at a sufficiently high speed to obtain a high ejector effect. Therefore, in the present embodiment, the flow path area at the downstream end of the nozzle portion 58a is configured to satisfy a / D ≧ 0.5.

  Further, in the present embodiment, in order to prevent pressure non-uniformity from occurring in the nozzle portion 58a and the downstream straight portion 58b, thereby reducing the exhaust suction force to the downstream side, the upstream side of the nozzle portion 58a. The inner surface of the portion 58a_1 bulges in the direction perpendicular to the gas flow direction with respect to the downstream end of the independent exhaust passage 52. Specifically, the upstream portion 58a_1 of the nozzle portion 58a is formed of a cylinder having an inner diameter larger than the inner diameter of the downstream end of the throttle portion main body 54, and the downstream portion 58a_2 of the nozzle portion 58a is directed downstream. Accordingly, the channel area is reduced.

  The straight part 58b is a cylinder extending downstream from the downstream end of the nozzle part 58a, and extends in the upstream / downstream direction with the same flow area as the flow area at the downstream end of the nozzle part 58a. The diffuser portion 58c is a substantially frustoconical cylindrical member whose flow path area increases from the downstream end of the straight portion 58b toward the downstream side.

  As described above, in the portion from the nozzle part 58a to the straight part 58b, the flow area on the upstream side is set larger than that on the downstream side. Therefore, the exhaust discharged from the throttle body 54 passes through the nozzle portion 58a and the straight portion 58b at high speed. At this time, since the pressure and temperature of the exhaust gas are reduced, the amount of heat released to the outside of the exhaust gas can be kept small in the nozzle portion 58a and the straight portion 58b. And the exhaust which passed the straight part 58b flows in into the diffuser part 58c which a flow-path area expands as it goes downstream, the pressure and temperature are recovered | restored, and it is discharged | emitted downstream, maintaining a high temperature. .

  In this embodiment, the nozzle part 58a, the straight part 58b, and the diffuser part 58c are inserted into the hollow outer pipe 58d, and the part from the nozzle part 58a to the diffuser part 58c has a double pipe structure. . For this reason, when passing through the collecting portion 58 composed of these nozzle portions 58a and the like, heat radiation to the outside of the exhaust gas is further suppressed, and exhaust gas at a high temperature is discharged from the collecting portion 58 to the downstream side.

(2-4) Configuration of the Catalyst Device 60 As shown in FIG. 1, the catalyst device 60 is a device for purifying the exhaust discharged from the engine body 1. The catalyst device 60 includes a catalyst body (catalyst) 64 and a casing 62 that houses the catalyst body 64. The casing 62 has a substantially cylindrical shape extending in parallel with the exhaust flow direction. The catalyst body 64 is for purifying harmful components in the exhaust. The catalyst main body 64 has, for example, a three-way catalyst function in an atmosphere having a theoretical air-fuel ratio, and contains a three-way catalyst.

  The catalyst main body 64 is accommodated in a central portion in the upstream / downstream direction of the casing 62, and a predetermined space is formed at the upstream end 61 of the casing 62. The downstream end of the collecting portion 58, specifically, the downstream end of the diffuser portion 58c is connected to the upstream end 61 of the casing 62, and the exhaust discharged from the diffuser portion 58c flows into the upstream end 61 of the casing 62. Progress toward the catalyst body 64 side.

  As described above, the exhaust gas having a high temperature is discharged from the collecting portion 58 to the downstream side. Therefore, the catalyst device 60 is directly connected to the gathering portion 58 in this manner, so that high-temperature exhaust gas flows into the catalyst device 60, whereby the catalyst body 64 is activated early. The active state of the main body 64 is reliably maintained.

(3) Control System FIG. 3 is a block diagram showing an engine control system. The ECU 90 shown in FIG. 3 is a device (control means) for comprehensively controlling each part of the engine, and includes a known CPU, ROM, RAM, and the like.

  Various information is input to the ECU 90 from various sensors provided in the engine. The ECU 90 is electrically connected to a crank angle sensor SW2 and an intake air amount sensor SW4 provided in the engine, and based on input signals from these sensors SW2 and SW4, the engine speed Ne, the intake air amount, and thus the engine load. Various information such as T is acquired.

  The ECU 90 includes a determination unit 91, an intake / exhaust control unit 92, and a rotation actuator control unit 94 as main functional elements.

  The determination means 91 determines in what manner the engine should be controlled on the basis of the engine speed Ne and the engine load T. FIG. 16 is a setting diagram (control map) showing separately the types of control determined based on the engine speed Ne and the load T. During operation of the engine, the determination unit 91 determines the control content of the engine so as to follow the control map of FIG.

  In the control map of FIG. 16, the first operation region A1 is set in the low speed and high load region where the engine load T is the reference load T1 or more out of the low speed region where the engine speed Ne is the reference rotation number N1 or less. The second operation area A2 is set in the other area. The second operation region A2 includes a high speed region A2_1 where the engine speed Ne is equal to or higher than the reference speed N1, and a low speed low where the engine load T is equal to or lower than the reference load T1 in a low speed region where the engine speed Ne is less than the reference speed N1. The load area A2_2. In the present embodiment, the reference load T1 is set so as to increase as the engine speed Ne increases. Further, the reference rotation speed N1 is set, for example, in the vicinity of 2500 rpm.

  The determination means 91 determines whether the engine operating point (the point on the control map specified from each value of the load T and the rotational speed Ne) is the first operating area A1 or the second operating area A2 during engine operation. Always determine whether it is.

  Returning again to FIG. 3, the intake / exhaust control means 92 changes the opening / closing timing of the intake valve 19 and the exhaust valve 20 by driving the intake VVT 32 and the exhaust VVT 42.

  The rotation actuator control means 94 drives the rotation actuator 56c to rotate the rotation shaft 56b and the partition wall 56, and thus each partition wall 56a, so that the position of each partition wall 56a is divided between the partition position and the communication position. Switching, the state of the throttle body 54 is switched between the independent distribution state and the communication state.

  In addition, the ECU 90 appropriately controls the spark plug 15 and the like according to the operating state.

(4) Control contents in each operation region Next, based on the control of the ECU 90 having the above functions, what kind of control is performed in each operation region (A1, A2) shown in FIG. I will explain. The ECU 90 sequentially determines which operating region the engine operating point (load T and rotation speed Ne) corresponds to in the control map of FIG. 16 based on the detected values of the crank angle sensor SW2 and the intake air amount sensor SW4. . Then, the following control is executed depending on whether the determined operation region is the first operation region A1 or the second operation region A2 in FIG.

(I) 1st operation area A1
In the first operation region A1, as shown in FIG. 4, the valve opening period of the exhaust valve 20 and the valve opening period of the intake valve 19 overlap with each other with the intake top dead center (TDC) interposed therebetween, and the exhaust valve 20 is adjusted to start valve opening during the overlap period T_O / L of the other cylinders 12. Specifically, the exhaust valve 20 of the third cylinder 12c is opened during the period in which the intake valve 19 and the exhaust valve 20 of the first cylinder 12a overlap, and the intake valve 19 and the exhaust valve of the third cylinder 12c are opened. The exhaust valve 20 of the fourth cylinder 12d is opened during the period in which the second cylinder 12d overlaps with the exhaust valve 20, and the second cylinder 12b during the period in which the intake valve 19 and the exhaust valve 20 of the fourth cylinder 12d overlap. The exhaust valve 20 of the first cylinder 12a is opened, and the exhaust valve 20 of the first cylinder 12a is adjusted to open during the period in which the intake valve 19 and the exhaust valve 20 of the second cylinder 12b overlap.

  Further, in the first operation region A1, the position of each partition wall 56a is set as the partition position, and the state in the throttle portion 53 is set to the independent circulation state. That is, the exhaust gas discharged from each independent exhaust passage 52 individually passes through each gas passage space 57 corresponding to each independent exhaust passage 52 and has a channel area set smaller toward the downstream side. Then, it is controlled so as to flow into the collecting portion 58.

  By controlling in this way, in the first operation region A1, the exhaust valve 20 of the predetermined cylinder (exhaust stroke cylinder) 12 is opened, and the collecting portion passes from the exhaust stroke cylinder 12 through the predetermined gas passage space 57. When the exhaust gas is discharged to 58 at a high speed, a gas passage space corresponding to another cylinder (intake stroke cylinder) whose exhaust sequence is set immediately before the exhaust stroke cylinder 12 and an exhaust port connected to the cylinder 12 A negative pressure is generated in 18 by the ejector effect. Since the intake stroke cylinder is in the overlap period when the exhaust valve 20 of the exhaust stroke cylinder 12 is opened, most of the residual gas in the intake stroke cylinder 12 is sucked out to the exhaust port 18 side by the negative pressure. The scavenging of the intake stroke cylinder 12 is promoted. In particular, immediately after the exhaust valve 20 starts to open, exhaust (so-called blowdown gas) is discharged from the cylinder 12 at a very high speed. Therefore, immediately after the blowdown gas is discharged, the residual gas in the intake stroke cylinder 12 is exhausted. Most of the air is sucked out to the exhaust port 18 side. When scavenging is promoted, the intake efficiency increases. Accordingly, a high engine torque is realized in the first operation region A1. Moreover, high engine torque is also realized by enabling the ignition timing to be advanced as the amount of residual gas in the cylinder 12 decreases and knocking is suppressed.

  In this device, the opening timing and closing timing of the intake valve 19 and the exhaust valve 20 are respectively shown in FIG. 17 where the lift rises or falls steeply in the lift curves of the valves 19 and 20, respectively. This is the time (the end of the ramp part or the start time), for example, the time of 0.4 mm lift.

(Ii) High speed area A2_1 of the second operation area A2
In the second operating region A2, the exhaust flow rate is large in the high speed region A2_1 where the engine speed Ne is high. Therefore, in the high speed region A2_1, as in the first operation region A1, the exhaust discharged from each independent exhaust passage 52 is discharged into the gas passage space 57 whose flow area decreases as it goes downstream. The deterioration of the scavenging performance due to the increased back pressure is greater than the scavenging performance improvement effect due to the effect. Therefore, the following control is performed in the high speed region A2_1.

  In the high speed region A2_1, the valve opening period of the exhaust valve 20 and the valve opening period of the intake valve 19 are adjusted so as not to overlap. Moreover, in 2nd driving | operation area | region A2, the position of each partition wall 56a is made into a communication position, and the state in the aperture | diaphragm | squeeze part 53 is made into a communication state. That is, the three gas passage spaces 57 communicate with each other, and the exhaust discharged from each independent exhaust passage 52 flows into the gas passage spaces 57 respectively corresponding to the individual exhaust passages 52, and then enters the gas passage spaces 57. In addition, it is controlled to flow into the gas passage space corresponding to the other independent exhaust passage 52.

  By being controlled in this way, in the high speed region A2_1 of the second operation region A2, the exhaust exhausted from each independent exhaust passage 52 is formed in the throttling portion 53 by the three gas passage spaces 57. It passes through a space having a larger flow path area than one operation region A1. Therefore, the exhaust resistance generated in the throttle portion 53 is suppressed to a small level. Thus, by suppressing the exhaust resistance to a small value, in the high-speed region A2_1, the pumping loss of the exhaust is suppressed to a small level, and the intake efficiency is increased, thereby realizing a high engine torque and a high thermal efficiency.

(Iii) Low speed and low load region A2_2 of the second operation region A2
In the second operating region A2, in the low speed and low load region A2_2 where the engine speed Ne is low and the engine load T is low, the intake pressure is low and the in-cylinder gas amount is small. Therefore, high scavenging is performed by the ejector effect, and accordingly, when the residual gas amount in the cylinder 12 decreases, the pumping loss of the intake air increases, and the combustion temperature increases and the cooling loss increases. An undesirable effect on thermal efficiency occurs. In the first place, in the low-speed and low-load region A2_2, the required fresh air amount is small, and there is little need to obtain high intake efficiency associated with the ejector effect.

  Therefore, in the low-speed and low-load region A2_2, as in the high-speed region A2_1, the position of each partition wall 56a is set to the communication position so that the ejector effect is not exhibited, and the state in the throttle portion 53 is set to the communication state.

  However, in the low speed and low load region A2_2, it is desirable that the residual gas is large as described above. Therefore, in the low-speed and low-load region A2_2, unlike the high-speed region A2_1, the valve opening period of the exhaust valve 20 and the valve opening period of the intake valve 19 are controlled to overlap so that more residual gas can be obtained. The

  By being controlled in this way, in the low speed and low load region A2_2 in the second operation region A2, the exhaust discharged from each independent exhaust passage 52 passes through a space having a larger flow path area in the throttle portion 53. Thus, the ejector effect and thus scavenging is suppressed. When the scavenging is suppressed, more residual gas remains in the cylinder 12. Therefore, in the low-speed and low-load region A2_2, the intake pumping loss and the cooling loss are reduced, and high thermal efficiency, that is, high fuel efficiency performance is realized.

(5) Operational Effect As described above, the present device has a simple configuration in which the state in the throttle unit 53 is switched between the independent flow state and the communication state, and is high using the ejector effect in the first operation region A1. While obtaining the engine torque, the exhaust resistance can be suppressed in the high speed region A2_1 in the second operation region A2 to obtain high engine torque and fuel efficiency, and the low speed and low load region A2_2 in the second operation region A2. The remaining gas can be secured by suppressing scavenging and high fuel efficiency can be obtained.

  In particular, in the present embodiment, when the state in the throttle part 53 is in the communication state, all three gas passage spaces 57 are in communication, and the volume of the space in the throttle part 53 through which the exhaust passes and the flow path area Is secured larger. Therefore, the exhaust resistance can be more reliably suppressed in the high speed region A2_1 of the second operation region A2, and the scavenging is more reliably suppressed in the low speed and low load region A2_2 of the second operation region A2. More can be secured.

  In the present embodiment, the partition 56 is rotated to change the partition state of the inner space of the throttle portion 53, thereby switching the state in the throttle portion 53 between the independent flow state and the communication state. Switching is realized with a simple configuration.

  Further, the configuration is such that the flow passage area of the space through which the exhaust exhausted from each independent exhaust passage 52 passes is changed by changing the partition state of the inner space of the throttle portion 53 in this way. In order to suppress the exhaust resistance in the high speed region and excessive scavenging in the low speed and low load region, the passage is configured so that the flow path area becomes smaller toward the downstream side to obtain the ejector effect. The distance from the independent exhaust passage 52 to the collecting portion 58 can be shortened as compared with the case where the passage for bypassing the ejector passage is provided separately, and flows into the catalyst device 60 directly connected to the collecting portion 58. It is possible to keep the exhaust temperature high. Therefore, scavenging activation of the catalyst body 64 or activity maintenance of the catalyst body 64 can be promoted.

(6) Other Embodiments In the first embodiment, each partition wall 56a is separated from the partition position by 60 degrees from the partition position, and each partition wall 56a is directed from the central axis L toward the center of the first virtual circle 201. Although the case of switching to any one of the communication positions that extend is shown, the position of each partition wall 56a, that is, the partition wall 56 may be changed more finely according to the operating conditions. For example, as shown by the arrow in FIG. 18, the amount of deviation from the partition position, that is, the partition wall, increases as the engine speed Ne increases more than the low speed and high load region (first operation region) A1 and the engine load T decreases. The amount of rotation 56 may be increased. Specifically, in the second operation region A2, in the region A2_2b where the engine speed is lower and the engine load is higher than the second reference load T2 substantially parallel to the reference load T1, each partition wall 56a is separated from the partition position by 30. You may make it deviate. In the region A2_2b, each partition wall 56a may be continuously shifted from the partition position as the engine speed increases and the engine load increases as indicated by the arrows in FIG. For example, the rotation amount of the partition wall 56 may be continuously changed between 0 to 60 degrees.

  Here, when the amount of rotation of the partition wall 56 is small and the amount of deviation from the partition position of the partition wall 56 is small, most of the exhaust exhausted from each independent exhaust passage 52 corresponds to the gas passage space 57 corresponding to the other independent exhaust passage. The amount toward the gas passage space 57 side corresponding to 52 is reduced. Then, more exhaust gas passes through one corresponding gas passage space 57, that is, a space configured to obtain the ejector effect. Therefore, in this case, it is possible to obtain a relatively high ejector effect, that is, a scavenging performance, while appropriately suppressing the exhaust resistance.

  Thus, as described above, if the rotation amount of the partition wall 56 is increased as the engine speed Ne increases from the low speed and high load region A1, the exhaust flow rate associated with the increase in the engine speed Ne can be obtained while obtaining the ejector effect. The exhaust resistance can be appropriately suppressed according to the increase, and the scavenging performance can be further enhanced. In addition, as the engine load T is lower than the low speed and high load region A1, the required fresh air amount is reduced and the required residual gas amount is increased, the amount of rotation of the partition wall 56 is increased to reduce the ejector effect. By doing so, it is possible to appropriately adjust the residual gas amount according to the engine load and obtain high fuel efficiency.

  Further, the detailed structure of the diaphragm 53 is not limited to the above. For example, as shown in FIG. 19, the opening 254a at the upstream end of the throttle unit body 254 of the throttle unit 253 is circular, and the space in the throttle unit main body 254 has a downstream end with a smaller area than the opening 254a at the upstream end. A substantially frustoconical shape in which the flow path area gradually decreases toward the circular opening 254b may be used. A partition wall 256 having a plurality of partition walls 256a extending radially outward from the central axis of the throttle body 254 is used as a gas passage space 257 having a fan-shaped cross section in the entire upstream and downstream direction. You may make it partition.

  In this embodiment, the partition walls 256 and thus the partition walls 256a are rotated around the central axis of the throttle body 254 as in the first embodiment. Each partition wall 256a divides the space in the throttle body 254 into three gas passage spaces 257 that individually communicate with the independent exhaust passages 52 as shown in FIG. Are separated from each of the compartment positions as shown in FIG. 20 in the independent circulation state where the exhaust discharged from each independent exhaust passage 52 independently flows into the corresponding gas passage space 257. The state moves to a communication position where a plurality of gas passage spaces communicate with each other. Here, FIG. 19 corresponds to FIG. FIG. 20 corresponds to FIG.

  In this embodiment, the leading end portion 256a_1 of each partition wall 256a is always in contact with the inner peripheral surface 254d of the throttle portion main body 254 regardless of the rotational position. Therefore, in a state where each partition wall 256a is rotated to the communication position shown in FIG. 20, the two adjacent gas passage spaces 257 communicate with each other, and the exhaust discharged from each independent exhaust passage 52 becomes two gas passage spaces. 257.

  In this way, only two gas passage spaces 257 of the three gas passage spaces 257 may communicate with each other in the communication state. However, if all of the three gas passage spaces 257 are in communication, the volume of the space through which the exhaust gas in the throttle portion 253 passes and the flow path area can be increased in the communication state, and the exhaust resistance can be suppressed to a lower level. Can do.

12 cylinder 18 exhaust port 19 intake valve 20 exhaust valve 52 independent exhaust passage 53 throttle part 54 partition (switching means)
56c Rotating actuator (switching means)
60 catalytic device 90 ECU (control means)

Claims (7)

An intake / exhaust device for a multi-cylinder engine having a plurality of cylinders each having an intake port and an exhaust port, and provided with an intake valve capable of opening and closing the intake port and an exhaust valve capable of opening and closing the exhaust port. ,
An independent exhaust passage which is connected to exhaust ports of one cylinder or a plurality of cylinders whose exhaust sequences are not continuous with each other and through which exhaust passes,
A collecting portion that is provided on the downstream side of each independent exhaust passage and the exhaust that has passed through each independent exhaust passage gathers inside;
A throttle part interposed between each of the independent exhaust passages and the collecting part, through which the exhaust discharged from the independent exhaust passages passes;
Independent flow that divides the space in the restricting portion into a plurality of gas passage spaces individually communicating with the independent exhaust passages so that the exhaust discharged from the independent exhaust passages passes through the restricting portions independently of each other. Switching means capable of switching the state of the throttle portion between a state and a communication state in which the gas passage spaces corresponding to the independent exhaust passages communicate with each other;
Valve driving means capable of driving the intake valve and the exhaust valve of each cylinder;
Control means capable of controlling the switching means and the valve driving means,
Each gas passage space is adjacent to another gas passage space as exhaust gas is discharged from the exhaust port of each cylinder through the independent exhaust passage and the gas passage space to the collecting portion in the independent flow state. The flow area on the downstream side is smaller than the flow area on the upstream side so that a negative pressure is generated in the exhaust port connected to the independent exhaust passage communicating with the gas passage space by the ejector effect. The gas passage spaces corresponding to the independent exhaust passages connected to the cylinders having the shape and the exhaust order are arranged adjacent to each other,
In the first operation region including at least a low speed and high load region in which the engine speed is lower than a preset reference speed and the engine load is higher than a preset predetermined load, the control means Between the cylinders in which the intake valve opening period and the exhaust valve opening period overlap with each other by a predetermined overlap period and the exhaust sequence is continued, the overlap period of one cylinder is the same as the exhaust valve of the other cylinder. While the valve driving means drives the intake valve and the exhaust valve of each cylinder so as to overlap with the valve opening time, the switching means makes the throttle portion in the independent flow state, while the engine In the second operation region including at least a high speed and high load region in which the engine speed is higher than the reference engine speed and the engine load is higher than a predetermined load set in advance. Serial intake and exhaust system for a multi-cylinder engine, characterized in that to the state of the throttle portion to said communicating state by the switching means. The intake / exhaust device for a multi-cylinder engine according to claim 1,
The second operating region includes a high speed region where the engine speed is higher than the reference speed, and a low speed and low load region excluding the low speed and high load region among regions where the engine speed is lower than the reference speed. An intake / exhaust device for a multi-cylinder engine. The multi-cylinder engine intake / exhaust device according to claim 1 or 2,
Three or more gas passage spaces corresponding to the independent exhaust passage and the independent exhaust passage are provided,
The throttle unit has a shape in which all the gas passage spaces communicate with each other in the communication state, and an intake / exhaust device for a multi-cylinder engine. The multi-cylinder engine intake / exhaust device according to any one of claims 1 to 3,
A partition wall capable of partitioning the space in the throttle part is provided in the throttle part,
The switching means places the partition in a position where the plurality of gas passage spaces are defined in the throttle, thereby setting the space in the throttle to the independent flow state, and the partition in the independent flow state. An intake / exhaust device for a multi-cylinder engine, wherein the space in the throttle portion is brought into the communication state by shifting a predetermined amount from The intake / exhaust device for a multi-cylinder engine according to claim 4,
Each independent exhaust passage and each gas passage space are arranged on a substantially circumference,
The partition wall extends radially outward from a central axis extending in the upstream / downstream direction through the center of the circumference where the gas passage spaces are arranged,
The multi-cylinder engine intake / exhaust device, wherein the switching means rotates the partition wall about the central axis. The intake / exhaust device for a multi-cylinder engine according to claim 5,
The second operating region includes a high speed region where the engine speed is higher than the reference speed, and a low speed and low load region excluding the low speed and high load region among regions where the engine speed is lower than the reference speed. Including
The control means increases the rotation amount of the partition wall by the switching means as the engine speed is higher than the low speed and high load area or as the engine load is lower than the low speed and high load area. A multi-cylinder engine intake and exhaust system characterized by The multi-cylinder engine intake / exhaust device according to any one of claims 1 to 6,
A catalyst device capable of purifying exhaust discharged from each cylinder;
The intake / exhaust device for a multi-cylinder engine, wherein the catalyst device is directly connected to a downstream end of the collecting portion.

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