JP2017180422A - Intake/exhaust system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intake/exhaust system for a multiple cylinder engine that can improve intake efficiency by a simple configuration to improve engine torque and fuel consumption performance.SOLUTION: In the intake/exhaust system for an internal combustion engine, a flow passage area providing an intersection point X between a change curve of a first clearance formed between an inner peripheral surface of an outer pipe 55 as a slide valve and an outer peripheral surface of an inner pipe 54 relative to a flow passage area and a change curve of a second clearance formed between an outer peripheral surface of the outer pipe 55 and an inner peripheral surface of a storage pipe 51a relative to a flow passage area is disposed on a side of a maximum flow passage area.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an intake / exhaust device for an internal combustion engine.

  2. Description of the Related Art Conventionally, in an engine such as an automobile, it has been known to employ a slide type dynamic pressure variable valve in an intake / exhaust device for the purpose of increasing engine torque (see, for example, Patent Document 1).

  The dynamic pressure variable valve mainly improves the scavenging performance when the engine is operated in the low rotation range. In the high rotation range, to suppress the influence of the exhaust resistance accompanying the increase in the exhaust gas flow rate. Then, the variable dynamic pressure valve is operated so as to enlarge the cross-sectional area of the exhaust gas passage.

JP2013-57255A

  By the way, in what was described in patent document 1, the outer pipe | tube as a dynamic pressure variable valve is arrange | positioned so that relative movement with respect to an inner pipe | tube is possible. Therefore, when the outer pipe slides, there is a problem that the outer pipe may vibrate and a rattling noise may occur if the exhaust gas pressure becomes high, and there is room for improvement.

  Accordingly, an object of the present invention is to provide an intake / exhaust device including a dynamic pressure variable valve that can suppress the generation of rattling noise even when the exhaust gas pressure is high during the operation of the dynamic pressure variable valve.

  In order to achieve the above object, in the present invention, a change curve of the clearance formed between the inner surface of the outer tube as the slide valve and the outer surface of the inner tube with respect to the flow area of the exhaust gas passage, the outer surface of the outer tube and the housing The channel area that gives the intersection of the clearance formed between the inner surface and the change curve with respect to the channel area of the exhaust gas passage is arranged on the maximum channel area side.

  That is, an intake / exhaust device for an internal combustion engine disclosed herein includes a plurality of intake ports and exhaust ports, and an intake valve capable of opening and closing the intake port and an exhaust valve capable of opening and closing the exhaust port. A plurality of independent exhaust passages whose upstream ends are respectively connected to the downstream ends of exhaust ports of one cylinder or a plurality of cylinders whose exhaust sequences are not continuous with each other; A throttle part connected to the downstream end of the independent exhaust passage and having a flow passage area at least downstream that is smaller than each upstream independent exhaust passage, and connected to the downstream end of the throttle part, and each independent exhaust passage And a collecting portion where the exhaust gas that has passed through the restricting portion gathers inside, and an accommodating portion that accommodates the restricting portion and the collecting portion, and the restricting portion is connected so that the independent exhaust passages are close to each other 1 done An inner pipe and an outer pipe fitted to the inner pipe so as to be relatively movable in the upstream and downstream directions at the upstream side portion, and the gathering portion is a downstream side extended to the downstream side of the outer pipe The inner pipe is provided so as to pass through a plurality of communication passages that connect the independent exhaust passages and the collective portion, and a wall portion of the inner pipe, and an upstream end of each communication passage. And a plurality of communication ports for communicating an intermediate portion between the downstream end and a gap space formed between the inner tube and the outer tube, and when the outer tube moves to the closed position of the upstream moving end, The inner surface of the outer pipe closes the communication port so that the opening of the communication port is minimized, and the flow channel area at the downstream end of the throttle portion is the minimum flow channel area, while the outer tube is open at the downstream moving end. When the movement is performed, the opening of the communication port is maximized and the flow path area at the downstream end of the throttle portion is the maximum flow area. As described above, by changing the amount of movement of the outer pipe in the upstream / downstream direction, it is possible to change the opening of the communication port and change the flow passage area of the throttle portion downstream end, and the throttle portion downstream end A first clearance that increases along a first curve is formed between the inner surface of the outer tube and the outer surface of the inner tube as the flow path area increases, and the outer surface of the outer tube and the housing portion A second clearance that decreases along a second curve is formed between the first curve and the second curve, wherein the first curve and the second curve are within the change range of the flow path area at the downstream end of the throttle portion. The clearance area where the clearance amounts of the first clearance and the second clearance are equal to each other, and the flow path area at the downstream end of the throttle portion at the intersection of the first curve and the second curve is the minimum flow path area and the maximum flow path It is characterized by being larger than the intermediate value with the area.

  The first clearance and the second clearance are the same at the outer pipe position of the flow path area at the downstream end of the throttle portion that gives the intersection of the first curve and the second curve. At this time, the outer pipe is the inner pipe and It is the position farthest away from any of the housing parts. If the exhaust gas pressure increases in this state, the outer tube vibrates and causes a rattling sound.

  According to the present invention, the first and second clearances are set so that the flow path area of the downstream end of the throttle portion at the intersection is larger than the intermediate value between the minimum flow path area and the maximum flow path area. When the flow passage area is relatively large, that is, when the exhaust gas pressure is relatively low, the outer tube is the most distant from both the inner tube and the accommodating portion, so the outer tube is most prone to vibration. Even in the state, the input of exhaust gas pressure is small, and the generation of rattling noise can be suppressed.

  In the present invention, the “first curve” and the “second curve” are concepts including a straight line.

  In a preferred aspect, the inner pipe has an inner pipe abutting portion that abuts the inner peripheral surface of the outer pipe at the outer peripheral portion when the flow passage area at the downstream end of the throttle portion is the minimum flow passage area. On the other hand, the outer tube includes, on the outer peripheral surface thereof, an outer tube contact portion that contacts the inner peripheral surface of the housing portion at the outer peripheral portion when the flow passage area at the downstream end of the throttle portion is the maximum flow passage area. The first clearance is a clearance between the outer peripheral portion of the inner tube contact portion and the inner peripheral surface of the outer tube, and the second clearance is the outer periphery portion of the outer tube contact portion and the housing. It is clearance with the inner peripheral surface of a part.

  According to this configuration, when the outer tube is in the closed position or the open position, the outer tube is supported by the inner peripheral surface of the inner tube abutting portion or the accommodating portion, respectively, so that the outer tube can be stably held. it can.

  In a preferred aspect, the outer peripheral portion of the inner tube abutting portion and the outer peripheral portion of the outer tube abutting portion are inclined such that the outer diameter of the throttle portion axial section increases toward the upstream side of the throttle portion. The outer circumferential surface of the inner tube is in contact with the inner circumferential surface of the outer tube, and the inner circumferential surface of the receiving tube that is in contact with the outer tube contacting portion. And an arcuate surface shape in which the corresponding contact portion is inverted so as to come into airtight contact with the outer peripheral portion of the outer tube contact portion.

  According to this configuration, when the outer tube comes into contact with the inner tube or the housing portion, it comes into contact with the arc surface as described above, so that it is possible to receive the impact force due to the contact of these parts over a wider area. It is possible to suppress the deterioration of the parts accompanying the movement of the tube and improve the durability of the apparatus.

  In a preferred aspect, the flow passage area changing means capable of changing the flow passage area at the downstream end of the throttle portion, the valve driving means capable of driving the intake valve and the exhaust valve of each cylinder, the flow passage area changing means, and the And a control means capable of controlling the valve drive means, wherein the control means is configured such that the engine speed of the internal combustion engine is higher than a preset reference speed by the flow path area changing means, and the load of the internal combustion engine is increased. In the first operation region including at least a high speed and high load region higher than a predetermined load set in advance, the flow passage area at the downstream end of the throttle portion is set as the maximum flow passage area, while the engine speed of the internal combustion engine is set to the reference In a second operation region including at least a low-speed and high-load region in which the load of the internal combustion engine is lower than the rotational speed and higher than a predetermined load set in advance, the flow passage area at the downstream end of the throttle portion is set to the maximum flow passage area. With the valve driving means, the opening period of the intake valve and the opening period of the exhaust valve of each cylinder overlap each other by a predetermined overlap period, and one of the cylinders in which the exhaust sequence is continued The intake valve and the exhaust valve of each cylinder are operated so that the overlap period of the cylinder overlaps with the time when the exhaust valve of the other cylinder is open.

  In this configuration, in the first operation region including the high speed and high load region, the flow passage area at the downstream end of the throttle portion is the maximum flow passage area, and the exhaust gas discharged from each independent exhaust passage has a smaller resistance in the throttle portion. It is controlled to pass in the state. Therefore, in this first operating region, it is possible to suppress the exhaust resistance that increases as the exhaust gas flow rate increases, to reduce the exhaust pumping loss, and to increase the intake efficiency. In this case, high engine torque and high thermal efficiency can be obtained.

  Further, in a state where the engine is operated in the second operation region and the flow path area at the downstream end of the throttle portion is smaller than the maximum flow path area, the engine collects from the exhaust port of each cylinder through each communication path. As the exhaust gas is discharged to the part, negative pressure is generated by the ejector effect in the other communication path and the exhaust port communicating with the communication path. Thus, scavenging performance can be improved by effectively utilizing the ejector effect in the second operation region including the low speed and high load region, and thus high engine torque can be obtained. Further, since the exhaust resistance can be kept small in the second operation region including the low speed and high load region, high engine torque and high thermal efficiency can be obtained.

  As described above, according to the present invention, in the wider operation region including the first operation region and the second operation region, the flow path area at the downstream end in the throttle portion interposed between the independent exhaust passage and the collecting portion. The engine torque, thermal efficiency, and consequently fuel efficiency can be improved with a simple configuration of changing the engine.

  In a preferred aspect, the control means causes the flow area at the downstream end of the throttle portion to be the minimum flow area in the second operation region by the flow area changing means.

  In the second operation region A2, the flow area of the gas passage is made small so that the ejector effect is exhibited, thereby increasing the intake efficiency and the engine torque, while increasing the flow passage area of the gas passage in the first operation region A1. Resistance and pump loss can be suppressed, thereby increasing engine torque. In addition, by adopting a configuration in which the flow path area at the downstream end of the throttle portion is switched to one of the minimum flow path area and the maximum flow path area, the outer tube can be arranged at the closed position or the open position, thereby generating rattling noise. Can be effectively suppressed.

  In a preferred aspect, the control means causes the flow path area changing means to set the flow area at the downstream end of the throttle portion to the minimum flow area only when the engine speed of the internal combustion engine is on the low rotation side.

  For example, when the outer pipe is at the closed position where the flow path area at the downstream end of the throttle portion is minimized, if the exhaust gas temperature rises as the engine speed increases, the outer pipe adheres to the inner pipe at the closed position. There is a risk of doing. In this case, since the flow passage area at the downstream end of the throttle portion is the minimum flow passage area, the engine speed cannot be further increased.

  According to the present invention, since the stage of minimizing the flow passage area at the downstream end of the throttle portion is on the low rotation side of the engine speed, the possibility of the outer tube sticking to the inner tube at the closed position is reduced, and the durability of the device is reduced. Can be improved.

  As described above, according to the present invention, even when the outer tube is located farthest from both the inner tube and the housing portion, and the outer tube is most prone to vibration, the exhaust gas pressure rises gently, and rattling occurs. Generation of sound can be suppressed.

1 is a schematic configuration diagram of an intake / exhaust device for a multi-cylinder engine according to a first embodiment of the present invention. The schematic side view of FIG. The block diagram for demonstrating the control system of the intake / exhaust apparatus of the multicylinder engine of FIG. The figure for demonstrating the valve timing of an intake valve and an exhaust valve. The VV sectional view taken on the line of FIG. FIG. 6 is a cross-sectional view of the periphery of the throttle portion in a state where the outer tube is at a position where the flow path area is minimum. VII-VII line sectional drawing of FIG. VIII-VIII sectional view taken on the line of FIG. FIG. 6 is a cross-sectional view of the periphery of the throttle portion in a state where the outer tube is in the vicinity of the intermediate position of the flow path area. XX sectional drawing of FIG. FIG. 6 is a cross-sectional view of the periphery of the throttle portion in a state where the outer tube is at the maximum position of the flow path area. XII-XII sectional view taken on the line of FIG. The graph which shows the relationship between the ratio of the movable stroke of an outer tube with respect to the nozzle diameter of a throttle part downstream end, and exhaust gas pressure. The graph which shows the relationship of the 1st and 2nd clearance with respect to the opening degree of a communicating port, the flow-path area of a gas passage, and the movable stroke of an outer tube. The figure which showed the control map used with the intake / exhaust apparatus of the multicylinder engine which concerns on embodiment of this invention. The figure which showed the example of control of the flow-path area of a gas passage, and the position of an outer tube | pipe. The figure which showed the example of control of the flow-path area of the gas channel in all loads, and the position of an outer tube | pipe. The figure for demonstrating the valve opening timing and valve closing timing of an intake valve and an exhaust valve. FIG. 7A is a view corresponding to FIG. 7A of the aperture portion according to the third embodiment of the present invention. FIG. 7A is a view corresponding to FIG. 7A of the aperture portion according to the fourth embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or its application.

(First embodiment)
(1) Overall Configuration of Device FIG. 1 is a schematic configuration diagram of an intake / exhaust device (intake / exhaust device for an internal combustion engine) 100 for a multi-cylinder engine according to an embodiment of the present invention. FIG. 2 is a schematic side view of a part of FIG. FIG. 3 is a block diagram showing a control system of the intake / exhaust device 100 of the multi-cylinder engine. 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 the combustion chamber defined above the piston.

  The engine body 1 is a four-cycle engine, and as shown in FIG. 4, the cylinders 12a to 12d are ignited by the spark plug 15 at a timing shifted by 180 ° CA, and the intake stroke, compression stroke, and expansion stroke are performed. The stroke and the exhaust stroke are each configured to be shifted by 180 ° CA. 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 (intake ports) 17 and two exhaust ports (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 three independent exhaust passages 52 and a movable portion 51 in order from the upstream side.

(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, among the cylinders 12, the exhaust port 18 of the first cylinder 12a and the exhaust port 18 of the fourth cylinder 12d are individually connected to 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, in which the exhaust strokes are not adjacent to each other and the exhaust order is not continuous with each other, do not discharge exhaust from these cylinders 12b and 12c at the same time. 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. Further, 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 cross-sectional shape (opening shape) of the downstream end 52a of each independent exhaust passage 52 is circular. These circular downstream ends 52a are arranged at equal intervals on the circumference of a circle centered on a point O1 on an axis L (see FIG. 2) extending obliquely downward rearward.

(2-2) Configuration of Movable Part 51 The movable part 51 has a triple-pipe structure, and is connected to the throttle part 53 connected to the downstream end of each independent exhaust passage 52 and to the downstream end of the throttle part 53. A merging portion 58 and an accommodating pipe (accommodating portion) 51 a that accommodates the constricted portion 53 and the merging portion 58 inside are provided. The throttle portion 53 and the merging portion 58 are arranged in this order from the upstream side.

(2-2-1) Configuration of Restriction Unit 53 FIG. 6 shows a movable unit in a state where an outer tube 55 to be described later is located most upstream, that is, in a closed position of the upstream moving end (hereinafter referred to as a minimum channel area position). It is sectional drawing which expanded 51 vicinity and showed typically. 7 is a sectional view taken along the line VII-VII in FIG. 6 in order from the upper side. FIG. 7A shows only the throttle portion 53, FIG. 7B shows only the inner tube 54 described later, and FIG. FIG. FIG. 8 is a view showing only the throttle portion 53, (b) the inner tube 54, and (c) only the outer tube 55 in the sectional view taken along the line VIII-VIII of FIG.

  FIG. 9 is a view corresponding to FIG. 6, and is a cross-sectional view schematically showing an enlarged vicinity of the movable portion 51 in a state in which the outer tube 55 is slid downstream from the flow path area minimum position. . FIG. 11 is a diagram corresponding to FIG. 6, and is a cross-sectional view schematically showing an enlarged vicinity of the movable portion 51 in a state where the outer tube 55 has been slid to the position where the flow path area is maximum.

  The throttle unit 53 includes an inner tube 54 and an outer tube 55.

<About inner pipe>
The inner tube 54 is a tubular member extending in the upstream / downstream direction. Inside the inner pipe 54, first passages (communication passages) 54a extending in the upstream and downstream directions and corresponding to the independent exhaust passages 52 are formed. The first passage communicates each independent exhaust passage 52 with a collecting portion 58a described later. In the present embodiment, three first passages 54a are formed. In other words, the individual exhaust passages 52 are connected to each other by a single inner pipe 54.

  The inner tube 54 has an outer shape in which the upstream portion has a cylindrical shape centering on the axis L of the receiving tube 51a, and the downstream portion has a substantially truncated cone shape whose diameter decreases toward the downstream centering on the axis L. doing. That is, the outer peripheral surface (outer surface) 54g of the inner tube 54 is provided at the upstream side portion thereof and extends in parallel with the axis L, and is provided at the downstream side portion thereof and toward the downstream side. Accordingly, the inner tube side inclined surface 54g-2 having a substantially truncated cone surface shape inclined toward the axis L side. The diameter of the downstream end of the outer peripheral surface 54g of the inner tube 54 is set to about 2/3 of the diameter of the upstream end of the outer peripheral surface 54g of the inner tube 54, for example.

  An annular inner tube abutting portion 71 centering on the axis L is provided on the upstream partial cylindrical surface 54g-1 of the inner tube 54. The inner pipe abutting portion 71 has an outer peripheral portion 71a at the inner peripheral surface of the outer pipe 55 when an outer pipe 55 (to be described later) is at the minimum flow area (the flow area at the downstream end of the throttle portion is the minimum flow area). It abuts on the first abutment surface 72 formed on the (inner surface). In the present embodiment, the outer peripheral portion 71 a of the inner tube contact portion 71 has an arcuate surface shape in which the cross section in the axis L direction of the throttle portion 53 is inclined so that the outer diameter increases toward the upstream side of the throttle portion 53. Is formed. Then, the first abutment surface 72 as the outer peripheral surface of the outer tube with which the inner tube abutting portion 71 abuts causes the inner tube abutting portion 71 to be in airtight contact with the outer peripheral portion 71a of the inner tube abutting portion 71. It has an inverted arc surface shape. As a result, when the outer tube 55 is at the minimum flow channel area position, the outer tube 55 can be reliably supported by the inner tube 54 and the state of the minimum flow channel area can be stably maintained. Further, the impact force caused by the contact between the inner tube 54 and the outer tube 55 can be received over a wider area, the deterioration of both parts accompanying the movement of the outer tube 55 can be suppressed, and the durability of the apparatus can be improved. .

  The first passages 54a are arranged at equal intervals on the circumference of a circle centered on the axis L. Each of the first passages 54a has a portion on the axis L side of the inner peripheral surface thereof extending obliquely toward the axis L, and a portion of the inner peripheral surface on the side away from the shaft L is the inner tube 54. It has a shape extending along the outer peripheral surface 54g. With this shape, the flow area of each first passage 54a is smaller on the downstream side than on the upstream side.

  Specifically, the upstream end 54b of each first passage 54a has a circular shape as shown in FIG. On the other hand, as shown in FIG. 8, the downstream end 54c of each first passage 54a is an intersection of the axis L and the downstream end of the inner tube 54, that is, a point O2 that is the center point of the downstream end of the inner tube 54. Each of the three circles is divided into three regions, each having a substantially oval shape, and the opening area (flow channel area) is configured to be smaller than the opening area of the circular upstream end 54b of each first passage 54a. Yes. Each first passage 54a extends from the circular upstream end 54b to the downstream side with the same flow path area, and then gradually flows toward the downstream end 54c having a flow path area smaller than the upstream end 54b. It extends while reducing the area, that is, while reducing the diameter.

  The inner pipe 54 is disposed such that the circular upstream end 54 b of each first passage 54 a coincides with the downstream end 52 a of each independent exhaust passage 52. Therefore, the exhaust discharged from the downstream end 52a of each independent exhaust passage 52 individually (independently) flows into the corresponding first passage 54a.

  An intermediate portion between the upstream end 54b and the downstream end 54c of each first passage 54a is formed in the wall portion of the inner pipe 54 at a position corresponding to each first passage 54a. A communication port 54d is formed to communicate with a second passage (gap space) 55a formed between the inner tube 54 and the outer tube 55. Each communication port 54d opens to the inner tube side inclined surface 54g-2 of the outer peripheral surface 54g of the inner tube 54, and opens in the upstream / downstream direction, that is, in the direction parallel to the axis L. In the present embodiment, each communication port 54d is substantially circular. A total of three communication ports 54 d are formed in the wall portion of the inner tube 54.

<About the outer tube>
The outer tube 55 is a tubular member extending in the upstream / downstream direction. As shown in FIG. 6, one passage is formed inside the outer tube 55, and the inner tube 54 is accommodated in this passage. The inner peripheral surface 55g of the outer tube 55 extends along the outer peripheral surface 54g of the inner tube 54 in a state where the outer tube 55 is at the minimum position of the flow path area. That is, the inner peripheral surface 55g of the outer tube 55 includes a curved surface 55g-1 provided in the upstream portion thereof and forming a first contact surface 72 that contacts the inner tube contact portion 71, and a downstream portion thereof. The outer tube side inclined surface 55g-2 having a substantially frustoconical surface shape that is inclined toward the axis L as it goes downstream. The outer tube side inclined surface 55g-2 of the outer tube 55 is in contact with the inner tube side inclined surface 54g-2 of the inner tube 54 in a state where the outer tube 55 is at the position where the flow path area is minimum. The communication ports 54d are configured to be closed. In FIG. 6, the outer tube side inclined surface 55 g-2 and the inner tube side inclined surface 54 g-2 are shown a little apart for explanation.

  The outer tube 55 is movable relative to the inner tube 54 in the upstream / downstream direction. That is, the outer tube 55 is externally fitted to the inner tube 54 so as to be relatively movable in the upstream / downstream direction on the upstream side. In this embodiment, the inner tube 54 does not move, and the outer tube 55 slides in the upstream / downstream direction parallel to the axis L. In the present embodiment, the outer tube 55 is formed integrally with the junction 58, that is, slides in the upstream and downstream direction together with the junction 58.

  Specifically, as shown in FIG. 1, a slide actuator (flow path area changing means) 55f is disposed on the outer peripheral surface of the accommodating tube 51a. Upon receiving a command from the ECU 90, the slide actuator 55f moves the slider 76 disposed on the surface of the outer tube 55, and moves the outer tube 55 in parallel with the axis L to the position shown in FIG. 11 and the most downstream position shown in FIG. 11, that is, the open position of the downstream moving end (hereinafter referred to as the maximum flow path area position). The slide actuator 55f continuously changes the position of the outer tube 55 between the minimum flow path area position and the maximum flow path area position. Hereinafter, the amount of movement in the upstream / downstream direction from the minimum flow path area position of the outer pipe 55 is referred to as a movable stroke S.

  Further, on the outer peripheral surface side of the outer tube 55, an annular outer tube contact portion 73 centering on the axis L is provided. When the outer tube 55 is at the maximum flow channel area position (the flow channel area at the downstream end of the throttle portion is the maximum flow channel area), the outer tube abutting portion 73 is an inner peripheral surface of the accommodating tube 51a described later on the outer peripheral portion 73a. It abuts on the second abutment surface 74 formed on the surface. The outer peripheral portion 73a of the outer tube contact portion 73 is formed in an arcuate surface shape that is inclined so that the outer diameter increases toward the upstream side. The second abutment surface 74 as the inner circumferential surface of the receiving tube with which the outer tube abutting portion 73 abuts is inverted from the outer tube abutting portion 73 so as to abut on the outer peripheral portion 73a of the outer tube abutting portion 73 in an airtight manner. It has an arcuate surface shape. As a result, when the outer tube 55 is at the maximum flow channel area position, the outer tube 55 can be reliably supported by the housing tube 51a and the state of the maximum flow channel area can be stably maintained. Further, the impact force due to the contact between the outer tube 55 and the housing tube 51a can be received in a wider area, so that the deterioration of both parts accompanying the movement of the outer tube 55 can be suppressed, and the durability of the apparatus can be improved.

<About the gas passage of the throttle>
6, the outer tube 55 extends from the inner tube contact portion 71 of the inner tube 54 to the downstream end of the inner tube 54. As described above, in this state, the inner peripheral surface 55g of the outer tube 55 is in contact with the outer peripheral surface 54g of the inner tube 54, and the inner peripheral surface of the outer tube closes the communication port 54d. Opening is minimized. When the communication port 54d is closed, the exhaust discharged from each independent exhaust passage 52 flows through only the first passage 54a in the throttle portion 53. As described above, in a state where the outer tube 55 is at the minimum flow path area position, the gas passage formed in the throttle portion 53 and through which the exhaust can pass is constituted by only the first passage 54a, and the flow passage area of the gas passage. (Flow path area at the downstream end of the throttle portion) K is the minimum flow path area.

  On the other hand, as shown in FIG. 9, when the outer tube 55 slides downstream from the minimum flow path area position shown in FIG. 6, the inner peripheral surface 55 g of the outer tube 55 is downstream and the diameter from the outer peripheral surface 54 g of the inner tube 54. It is separated outward in the direction (direction away from the axis L). Therefore, as shown in FIG. 10, at the downstream end of the throttle portion 53, each communication port 54d opens as the inner peripheral surface 55g of the outer tube 55 and the outer peripheral surface 54g of the inner tube 54 are separated from each other. A second passage 55 a appears between the inner peripheral surface 55 g of the outer tube 55 and the outer peripheral surface 54 g of the inner tube 54.

  Thus, in a state where the outer tube 55 has slid downstream from the position of the smallest flow area shown in FIG. 6 to the position shown in FIG. 9, the gas passage formed in the throttle portion 53 is the first passage 54a and the second passage. The flow passage area K of each gas passage is larger than the minimum flow passage area shown in FIG. Then, after the exhaust discharged from each independent exhaust passage 52 flows into the first passage 54a, a part thereof also flows into the second passage 55a through the communication port 54d.

  In the present embodiment, the second passage 55a extends over the plurality of first passages 54a. However, the first passage 54a and the second passage 55a formed on the inner pipe-side inclined surface 54g-2 are provided. The communication port 54d that communicates with each other is opened in the upstream and downstream directions, and the flow passage cross-sectional area of the collecting portion 58a is larger than that of the second passage 55a, and therefore flows into the second passage 55a from the predetermined first passage 54a. The exhausted gas is maintained in the downstream direction, and flows down through the second passage 55a without going toward the other first passage 54a. Therefore, the occurrence of disturbance in the exhaust flow direction in the second passage 55a is suppressed, and a high ejector effect is exhibited.

  The flow passage area of the second passage 55a, that is, the flow passage area K of the gas passage of the throttle portion 53 increases as the sliding amount of the outer pipe 55 to the downstream side increases. Specifically, as the outer tube 55 slides downstream, the radial distance between the inner peripheral surface 55g of the outer tube 55 and the outer peripheral surface 54g of the inner tube 54 increases, and the second passage 55a accordingly. And the flow passage area of the gas passage is increased.

  In a state where the outer tube 55 is slid downstream to the maximum flow path area position shown in FIG. 11, as shown in FIG. 12, the inner peripheral surface 55g of the outer tube 55 and the outer periphery of the inner tube 54 at the downstream end of the throttle portion 53 The radial distance from the surface 54g is maximized, the opening of the communication port 54d is maximized, and the flow passage area K of the second passage 55a and the gas passage is the maximum flow passage area.

  The flow path area K of the gas passage in the throttle 53 is the same as when the gas passage is constituted by the first passage 54a and the second passage 55a, as in the case where the gas passage is constituted by only the first passage 54a. The downstream side is configured not to be larger than the upstream side. That is, the throttle portion 53 is formed so that the flow passage area K of each gas passage is equal to or smaller than the flow passage area of the downstream end 52a of each upstream independent exhaust passage 52. In the present embodiment, the channel area K of the gas passage is set to be the same as the channel area of the upstream end 54b of the first passage 54a at the maximum channel area position shown in FIG. By setting in this way, even if the exhaust gas flow rate in the high-load operation region is relatively large, the flow resistance is increased by reducing the flow passage area by the throttle portion 53, and the scavenging performance is reduced. That is restrained.

  Then, by changing the movable stroke S of the outer tube 55, the opening degree of the communication port 54d can be changed, and the flow path area K of the gas passage of the throttle portion 53 can be changed.

(2-2-2) Configuration of Merging Port Merging portion 58 is a portion where exhaust gas discharged from each independent exhaust passage 52 and passing through throttle portion 53 merges. Regardless of the position of the outer tube 55, the exhaust gas discharged from each independent exhaust passage 52 and flowing into each gas passage of the throttle portion 53 flows into the merge portion 58.

  As shown in FIG. 6 and the like, the merging portion 58 includes a collecting portion 58a, a mixing portion 58b, and a diffuser portion 58c in order from the upstream side. The gathering portion 58 a extends downstream from the downstream end of the outer tube 55. In other words, the gathering portion 58a is formed in the downstream side portion extending downstream of the outer tube 55. Accordingly, the exhaust gas that has passed through each of the independent exhaust passages 52 and the throttle portion 53 gathers inside the gathering portion 58a. In the present embodiment, as described above, the merging portion 58 is coupled to the outer tube 55 so as to be slidable.

  As shown in FIG. 9 and FIG. 11, in a state where the outer tube 55 is slid downstream from the position where the flow path area is minimum, the outer tube 55 extends downstream from the inner tube 54, and The volume increases over time. Then, the exhaust gas that has passed through the first passage 54a in the throttle portion 53 flows into the outer pipe 55, merges with the exhaust gas that has passed through the second passage 55a, and then flows into the collecting portion 58a.

  As will be described later, in the present apparatus, in a predetermined operation region (second operation region A2), the exhaust discharged from the predetermined cylinder 12 is discharged from the throttle portion 53 into the collecting portion 58a at a high speed, so that the ejector effect is achieved. And a negative pressure is generated in the exhaust port 18 of the other cylinder 12 to improve the scavenging performance of the cylinder 12. Therefore, the collecting portion 58a is set to have a shape in which the flow passage area becomes smaller toward the downstream side so that the exhaust discharged from the throttle portion 53 flows down while maintaining a high speed. In the present embodiment, the collective portion 58a has a substantially truncated cone shape that decreases in diameter toward the downstream. In addition, the inner peripheral surface of the collecting portion 58a has an inner peripheral surface of the downstream side portion of the outer tube 55, that is, an outer tube-side inclined surface, so that the exhaust gas flowing out from the throttle portion 53 smoothly flows along the inner peripheral surface. Continuing from 55g-2, it is inclined in a direction approaching the axis L as it goes downstream. In addition, the inclination angle with respect to the axis L of the collective portion 58a may be set to be substantially the same as the inclination angle of the outer tube side inclined surface 55g-2 of the outer tube 55.

  The mixing portion 58b has a cylindrical shape that extends downstream from the downstream end of the collecting portion 58a, and extends downstream while maintaining the same flow area as the downstream end of the collecting portion 58a. The diffuser portion 58c has a substantially frustoconical shape in which the flow path area increases as it goes downstream from the downstream end of the mixing portion 58b.

  Thus, in the gathering part 58a, the upstream flow path area is larger than the downstream side. Therefore, the exhaust gas passes through the collecting portion 58a and the mixing portion 58b at a high speed. During this passage, the pressure and temperature of the exhaust gas decrease. For this reason, in the collecting portion 58a and the mixing portion 58b, the amount of heat released to the outside of the exhaust is kept small. Then, the exhaust gas that has passed through the mixing portion 58b flows into the diffuser portion 58c whose flow area increases as it goes downstream, so that its pressure and temperature are recovered, and is discharged downstream while maintaining a high temperature. The

  Further, as described above, in the present embodiment, the merging portion 58 and the throttle portion 53 are inserted into the hollow housing tube 51a. Therefore, heat radiation to the outside of the exhaust when passing through the junction 58 and the throttle 53 is further suppressed, and high temperature exhaust is discharged from the junction 58 to the downstream side.

(2-2-3) Constitution of the containment tube As shown in FIG. 6, the containment tube 51a is a tubular member centered on the axis L, and has a substantially truncated cone shape whose diameter is mainly reduced toward the downstream. A portion that accommodates the throttle portion 53 and the collecting portion 58a, a convex portion that accommodates the mixing portion 58b including the slider 76, and a substantially frustoconical shape whose diameter increases mainly toward the downstream, and a diffuser portion 58c. And a receiving portion. In other words, the storage tube 51a is a tubular member having a shape that follows the outer peripheral surface of the outer tube 55 around the axis L. As described above, the outer tube contact portion 73 formed on the outer peripheral surface of the outer tube 55 contacts the second contact surface at the position where the flow path area is maximum as described above at a position near the collecting portion 58a on the inner peripheral surface of the housing tube 51a. 74 is formed.

(2-2-4) Clearance between Inner Tube-Outer Tube and Outer Tube-Accommodating Tube FIG. 13 is formed on the outer peripheral portion 71a of the inner tube contact portion 71 and the inner peripheral surface of the outer tube 55. The clearance between the first contact surface 72 is the first clearance C1, and the clearance between the outer peripheral portion 73a of the outer tube contact portion 73 and the second contact surface 74 formed on the inner peripheral surface of the housing tube 51a. The change with respect to the flow area K of the gas passage of the 1st and 2nd clearance C1, C2 when it is set as the 2nd clearance C2 is shown. The opening of the communication port 54d and the movable stroke S of the outer pipe 55 are 0 when the flow passage area K of the gas passage is minimum, while the communication opening is when the flow passage area K of the gas passage is maximum. The opening degree of 54d and the movable stroke S of the outer tube 55 are maximized.

  As shown in FIG. 13, the first clearance C <b> 1 increases along the first curve A as the flow area K of the gas passage increases.

  Further, the second clearance C2 decreases along the second curve B as the flow path area K of the gas passage increases.

  At this time, the first curve A and the second curve B have an intersection X where the clearance amounts of the first clearance C1 and the second clearance C2 are equal within the change range of the flow passage area K of the gas passage. . The first clearance C1 represented by the first curve A is kept smaller than the clearance amount given by the intersection point X from the minimum flow path area position to the flow path area position of the intersection point X. Further, the second clearance C2 represented by the second curve B is kept smaller than the clearance amount given by the intersection X from the flow path area position of the intersection X to the maximum flow path area position.

  Since high-temperature exhaust gas flows from each independent exhaust passage 52 to the throttle portion 53 and the confluence portion 58, the first tube is provided so that the outer tube 55 as a slide valve does not adhere to the inner tube 54 or the housing tube 51a during the slide. The clearance C1 and the second clearance C2 are set so as not to become 0 except for the minimum / maximum position of the flow path area, that is, the outer tube 55 is not in contact with the inner tube 54 or the housing tube 51a.

  Accordingly, the outer tube 55 is kept closer to the inner tube 54 than the housing tube 51a from the minimum flow channel area position to the flow channel area position of the intersection X, so to speak, it is in a non-contact state with the inner tube 54. It is supported by. Further, from the flow path area position of the intersection X to the maximum flow path area position, the outer tube 55 is kept closer to the housing tube 51a than the inner tube 54, and is so supported by the housing tube 51a in a non-contact manner. It will be in the state.

  And in the flow-path area position which gives the intersection X of the 1st curve A and the 2nd curve B, the 1st clearance C1 and the 2nd clearance C2 become the same. At this time, the outer tube 55 is located farthest from both the inner tube 54 and the housing tube 51a, and at this position, the support by the inner tube 54 is switched to the support by the housing tube 51a. Therefore, when the outer pipe 55 is at the flow path area position of the intersection point X, the outer pipe 55 is in a state where it is most likely to vibrate, and the possibility of rattling noise increases as the exhaust gas pressure increases.

  Here, in the intake / exhaust device according to the present embodiment, the channel area K of the gas passage at the intersection of the first curve A and the second curve B is an intermediate value between the minimum channel area and the maximum channel area. The first and second clearances C1 and C2 are set so as to be closer to the maximum flow path area than M.

  Hereinafter, the effect of this structure is demonstrated.

  For example, as shown in FIGS. 6 and 8 to 12, a point closest to the center point O2 at the opening edge of the downstream end 54c of each first passage 54a with respect to the center point O2 at the downstream end of the inner pipe 54 is shown. The first point P2 is defined as the second point Q2 where the inner pipe downstream end center point O2 and the straight line passing through the first point P2 intersect the inner peripheral surface of the outer pipe 55. And let the distance from the said 1st point P2 to the said 2nd point Q2 be the nozzle diameter D of each gas passage when assuming the equivalent circular diameter about the flow path area K of each gas passage. FIG. 14 shows a ratio S / D between the nozzle diameter D and the movable stroke S as the amount of movement in the upstream / downstream direction of the outer pipe 55, and plots the exhaust gas pressure against the ratio S / D. The engine speed (engine speed) is, for example, 4000 rpm.

  In FIG. 14, when the outer tube 55 is at the minimum position of the flow path area, the movable stroke S is 0 and the ratio S / D is 0. On the other hand, when the outer tube 55 is at the maximum position of the flow path area, the ratio S / D is 0.42. Then, when the outer pipe 55 is located at the flow path area position where the flow path area is the intermediate value M in FIG. 13, the ratio S / D is 0.23.

  As shown in FIG. 14, the exhaust gas pressure gradually decreases with an increase in the ratio S / D from 0 to 0.24, rapidly decreases from a point exceeding 0.24 to 0.33, At 0.33 or more, it is almost constant.

  Therefore, when the engine speed is a constant predetermined speed, in this case 4000 rpm, the first and second clearances C1 and C2 are set so that the ratio S / D exceeds 0.23, for example. The flow path area K of the gas passage that gives X can be made larger than the intermediate value M between the minimum flow path area and the maximum flow path area. As described above, the outer tube 55 is in a state where it is most likely to vibrate at the position of the outer tube 55 that gives the intersection point X. Therefore, by adopting this configuration, the flow passage area is increased and the exhaust gas pressure is relatively lowered. In this state, the intersection X is reached, so that the vibration of the outer tube 55 can be suppressed, and hence the generation of rattling noise can be suppressed.

  From the viewpoint of more effectively suppressing the vibration of the outer tube 55 and suppressing the generation of rattling noise, the ratio S / D is more preferably 0.24 or more, and particularly preferably 0.33 or more. It is desirable to set the first and second clearances C1 and C2.

  The flow passage area K of the gas passage is assumed to be an area of a circle having the nozzle diameter D as an equivalent circular diameter, that is, an equivalent circular area, and the maximum flow passage area K and the minimum flow passage area of the flow passage area K of the gas passage When the ratio Kp (%) of the change amount from the minimum flow passage area to the total flow change amount is calculated, the ratio S / D is 0.23, that is, the intermediate value M of the flow passage area K of the gas passage. When the ratio Kp is 53%, the ratio Kp is 56% when the S / D is 0.24, and the ratio Kp is 78% when the ratio S / D is 0.33. It is desirable to set the first and second clearances C1 and C2 so that the ratio Kp is preferably 54% or more, more preferably 56% or more, and particularly preferably 78% or more.

  As described above, according to this configuration, in the state in which the outer tube 55 is most likely to vibrate, the flow passage area K of the gas passage is larger than the intermediate value M, so that the input of exhaust gas pressure is small, and rattling noise is reduced. Occurrence can be suppressed.

(2-3) Configuration of 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 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 merging portion 58, specifically, the downstream end of the diffuser portion 58 c is connected to the upstream end 61 of the casing 62, and the exhaust discharged from the diffuser portion 58 c flows into the upstream end 61 of the casing 62. Then, the process proceeds to the catalyst body 64 side.

  As described above, high-temperature exhaust is discharged from the junction 58 to the downstream side. Therefore, the catalyst device 60 is directly connected to the merge portion 58 as described above, 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 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. Specifically, 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 (engine) Various information such as the number of revolutions (Ne), the intake air amount, and the engine load T is acquired.

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

  Based on the engine speed Ne and the engine load T, the determination means 91 determines in what manner the engine should be controlled. FIG. 15 is a setting diagram (control map) showing 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. 15, the second operation region A2 is set in the low speed and high load region where the engine load T is the reference load T1 or more in the low speed region where the engine speed Ne is the reference rotation number N1 or less. The first operation area A1 is set in this area. In the present embodiment, the reference load T1 is set so as to increase as the engine speed Ne increases. Further, the reference rotational speed N1 is set to, for example, around 4000 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 to FIG. 3 again, the intake / exhaust control means 92 changes the opening / closing timing of the intake valve 19 by driving the intake VVT 32.

  The actuator control means 94 drives the slide actuator 55 f to change the position of the outer tube 55, thereby changing the flow area of each gas passage in the throttle portion 53.

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

(4) Control contents The control contents in each operation region (first operation region A1, second operation region) implemented by the ECU 90 will be described.

  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. 15 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) Second operation area A2
In the second operation region A2 composed of the low speed and high load region, 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 the intake top dead center (TDC) interposed therebetween. In addition, the exhaust valve 20 is adjusted to start 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 second operation region A2, the position of the outer tube 55 is set upstream of the maximum flow channel area position, and the flow channel area K of each gas passage in the throttle portion 53 is smaller than the maximum area. Is done. Further, the position of the outer tube 55 is changed according to the engine speed Ne within a range where the flow area K of each gas passage is smaller than the maximum area.

  Specifically, as shown in FIG. 16 showing the flow passage area of the gas passage for each operation region and FIG. 17 showing the change of the flow passage area with respect to the engine speed, the unit increases as the engine speed Ne increases. Since the exhaust gas flow rate per hour increases, the position of the outer pipe 55 is changed to the downstream side, and the flow passage area of the gas passage is increased. That is, in the second operation region A2, when the load is constant, the position of the outer pipe 55 gradually decreases from the minimum flow path area position to the position immediately before the maximum flow path area position as the engine speed Ne increases. Is changed to the side.

  As will be described later, in the first operation region A1-1 on the higher rotation side than the second operation region A2, the position of the outer tube 55 is set to the maximum flow path area position. Therefore, by changing the position of the outer tube 55 as described above, the position of the outer tube 55 is smoothly switched at the boundary between the second operation region A2 and the first operation region A1. FIG. 17 shows the engine speed Ne and the position of the outer pipe 55 at the full load Tmax (see FIG. 15).

  Thus, in 2nd operation area | region A2, the flow-path area of the gas path in the throttle part 53 is controlled to the area below a maximum area. As a result, in the second operation region A2, the exhaust discharged from each independent exhaust passage 52 passes through the throttle portion 53 at a high speed and flows into the collecting portion 58a. In particular, as the engine speed Ne increases and the exhaust flow rate increases, the flow passage area of the gas passage is increased, and an increase in back pressure accompanying an increase in the exhaust flow rate is suppressed, so that the exhaust speed is appropriately increased. In this way, exhaust gas is discharged from the gas passage in the throttle portion 53 to the merging portion 58 at a high speed, so that a relatively negative pressure state is obtained compared to the upstream side, and the other adjacent gas passages are scavenged by the ejector effect. Is promoted.

  Here, in the second operation region A2, as described above, 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 gas is exhausted. The valve 20 is adjusted so as to start opening during the overlap period T_O / L of the other cylinders 12. Therefore, when the exhaust valve 20 of the predetermined cylinder (exhaust stroke cylinder) 12 is opened and the exhaust gas is discharged from the exhaust stroke cylinder 12 through the predetermined gas passage to the merging portion 58 at a high speed, the exhaust sequence is changed. A negative pressure is generated by an ejector effect in a gas passage corresponding to another cylinder (intake stroke cylinder) set immediately before the exhaust stroke cylinder 12 and in an exhaust port 18 connected to the intake stroke cylinder 12. . Then, when the exhaust valve 20 of the exhaust stroke cylinder 12 is opened, since the intake stroke cylinder is in the overlap period, the residual gas in the intake stroke cylinder 12 is sucked out to the exhaust port 18 side, and the intake stroke cylinder Scavenging within 12 is facilitated. 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 the scavenging is promoted, the intake efficiency increases, so that a high engine torque can be obtained. Further, since the residual gas amount in the cylinder 12 is reduced and knocking is suppressed, the ignition timing can be advanced, so that a high engine torque can be obtained.

  In this device, the opening timing and closing timing of the intake valve 19 and the exhaust valve 20 are respectively shown in FIG. 18, 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 region A1-1 of the first operation region A1
In the first operating range A1, the exhaust flow rate is large in the high speed range A1-1 where the engine speed Ne is equal to or higher than the reference speed N1. Therefore, in the high speed region A1-1, as in the second operation region A2, when the flow passage area of each gas passage is reduced, scavenging due to higher back pressure than the scavenging performance improvement effect due to the ejector effect. Degradation of performance is increased. Therefore, the following control is performed in the high speed region A1-1.

  In the high speed region A1-1, 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. In the high speed region A <b> 1-1, the position of the outer tube 55 is the maximum flow channel area position, and the flow channel area of each gas passage in the throttle 53 is the maximum area.

  By being controlled in this way, in the high speed region A1-1 in the first operation region A1, the exhaust discharged from each independent exhaust passage 52 passes through the throttle portion 53 in a state where the resistance is suppressed to a small value. . Therefore, in this high speed region A1-1, the exhaust resistance is suppressed to a low level, the pumping loss of the exhaust is suppressed to a low 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 A1-2 of the first operation region A1
In the first operating range A1, in the low speed and low load range A1-2 where the engine speed Ne is lower than the reference speed N1 and the engine load T is lower than the reference load T1, the intake pressure is low and the in-cylinder gas amount is low. Few. 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 A1-2, the required amount of fresh air 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 A1-2, as in the high speed region A1-1, the ejector effect is suppressed to be small, that is, the speed at which the exhaust gas flows into the merging portion 58 is suppressed to be small. With the position of the pipe 55 as the maximum channel area position, the channel area of each gas passage in the throttle 53 is the maximum area.

  However, in the low-speed and low-load region A1-2, since it is desirable that the residual gas is large as described above, the valve opening period of the exhaust valve 20 and the valve opening period of the intake valve 19 are obtained so that more residual gas can be obtained. Is adjusted to overlap.

  By being controlled in this way, in the low speed and low load region A1-2 of the first operation region A1, the exhaust discharged from each independent exhaust passage 52 passes through a space having a larger flow path area in the throttle portion 53. In addition, the ejector effect and thus scavenging is suppressed. By suppressing the scavenging, more residual gas remains in the cylinder 12. Therefore, intake pumping loss and cooling loss are reduced, and high thermal efficiency, that is, fuel efficiency performance is realized.

  As described above, the apparatus according to the present embodiment has a simple configuration in which the flow area of each gas passage in the throttle 53 into which the exhaust from each independent exhaust passage 52 flows independently is changed. In the second operation region A2, while obtaining high engine torque using the ejector effect, it is possible to obtain high engine torque and fuel efficiency by suppressing exhaust resistance in the high speed region A1-1 of the first operation region A1, In the low speed and low load region A1-2 of the first operation region A1, scavenging can be suppressed to ensure residual gas, and high fuel efficiency can be obtained.

  In particular, in the present embodiment, the flow area of each gas passage is increased as the engine speed Ne is increased in the second operation region A2. Therefore, in the second operation region A2, it is possible to effectively suppress the exhaust resistance, that is, the pump loss, which increases with the increase in the engine speed and thus the exhaust flow rate, and to effectively obtain the ejector effect.

(6) Other Embodiments Hereinafter, other embodiments according to the present invention will be described in detail. In the description of these embodiments, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

(6-1) Second Embodiment In the first embodiment, the case where the flow passage area K of the gas passage is increased as the engine speed Ne increases in the second operation region A2 is described. In this case, the flow path area K of the gas passage may be controlled to be fixed to an area (for example, the minimum area) smaller than the flow path area (maximum area) in the first operation region A1. Specifically, the slide actuator 55f is configured to switch the position of the outer tube 55 between the minimum flow channel area position and the maximum flow channel area position, and the outer tube 55 is set to the minimum flow channel area position in the second operation region A2. The first passage 54a and the second passage 55a are not in communication with each other, and the first passage 54a and the second passage 55a are in communication with each other in the first operation region A1 with the outer tube 55 as the maximum flow area. Also good. Even in this case, the ejector effect is exhibited by reducing the flow passage area of the gas passage in the second operation region A2, thereby increasing the intake efficiency and the engine torque, and the flow of the gas passage in the first operation region A1. The road area can be increased to suppress exhaust resistance and pump loss, thereby increasing engine torque.

  In addition, the outer pipe 55 can be disposed at the minimum flow path area position or the maximum flow path area position by switching the flow path area K of the gas passage to one of the minimum flow path area and the maximum flow path area. Therefore, generation of rattling noise can be effectively suppressed.

  In both the first embodiment and the second embodiment, from the viewpoint of suppressing scavenging deterioration due to an increase in back pressure, the flow passage area K of the gas passage is the minimum flow passage area. Only when Ne is on the relatively low rotation side.

(6-2) Third Embodiment In the first and second embodiments, an inner tube abutting portion 71 is provided on the cylindrical surface 54g-1 of the inner tube 54. When the outer tube 55 is at the minimum flow channel area position, the outer tube 71 abuts the first contact surface 72 formed on the inner surface of the outer tube 55. In place of providing the first contact surface 72, as shown in FIG. 19, the outer tube 55 is provided with partition walls 55e for partitioning the plurality of second passages 55a, and the inner tube 54 is provided with these partition walls 55e. It is good also as a structure which provides the groove | channel 54e which can slide.

  As shown in FIG. 19, in the tube wall of the inner tube 54, grooves extending from the outer peripheral surface 54g of the inner tube 54 toward the axis L and extending in the upstream / downstream direction at positions corresponding to the first passages 54a. 54e is formed.

  The outer tube 55 is formed with a plurality of partition walls 55e corresponding to the grooves 54e of the inner tube 54, extending from the inner peripheral surface 55g toward the axis L and extending in the upstream and downstream directions. These partition walls 55e are inserted into the respective grooves 54e.

  At this time, the partition walls 55e of the outer tube 55 slide in the grooves 54e of the inner tube 54.

  And between the inner peripheral surface 55g of the outer tube 55 and the outer peripheral surface 54g of the inner tube 54, three second passages 55a are partitioned by a partition wall 55e. Each second passage 55a is located on the radially outer side of each first passage 54a and communicates with the first passage 54a through each communication port 54d.

  In the present embodiment, the first clearance is a clearance between the outer peripheral surface including the groove 54e of the inner tube 54 and the inner peripheral surface including the partition wall 55e of the outer tube 55.

  According to this configuration, it is possible to effectively avoid the exhaust flowing into the second passage 55a from diffusing in the circumferential direction between the outer pipe 55 and the inner pipe 54 and reducing the speed of the exhaust. In the second operation region A2, a high ejector effect can be obtained while the first passage 54a and the second passage 55a are connected.

  Further, the first clearance from the minimum flow path area position to the flow path area position of the intersection X can be made smaller, and the support of the outer pipe 55 by the inner pipe 54 can be made more reliable.

(6-3) Fourth Embodiment In the first to third embodiments, the communication port 54d provided in the inner tube 54 has a substantially circular shape. However, the present invention is not limited to this, and there are various shapes such as an elliptical shape and a rectangular shape. Can be formed. Further, for example, as shown in FIG. 20, it may have a notch shape opened to the downstream end of the inner tube 54. Thereby, the manufacturing process of the inner tube 54 can be simplified, and the contact area between the inner peripheral surface of the outer tube 55 and the outer peripheral surface of the inner tube 54 is reduced when the outer tube 55 is at the minimum flow path area position. Therefore, deterioration of both parts can be suppressed.

  In the present invention, even when the outer tube is located farthest from both the inner tube and the housing, and the outer tube is most prone to vibrate, the exhaust gas pressure rises gently and the generation of rattling noise can be suppressed. So it is extremely useful.

12 cylinder 17 intake port (intake port)
18 Exhaust port (exhaust port)
19 Intake valve 20 Exhaust valve 30 Intake valve drive mechanism (valve drive means)
40 Exhaust valve drive mechanism (valve drive means)
51a accommodation pipe (accommodating part)
52 Independent exhaust passage 53 Restriction portion 54 Inner pipe 54a First passage (communication passage)
55 Outer tube 55a Second passage (gap space)
54d Communication port 55f Slide actuator (channel area changing means)
58a Collecting portion 71 Inner tube contact portion 71a (outer tube contact portion) outer peripheral portion 72 first contact surface 73 outer tube contact portion 73a (outer tube contact portion) outer peripheral portion 74 second contact surface 90 ECU (control means)
L axis

Claims (6)

An intake / exhaust device for an internal combustion 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,
A plurality of independent exhaust passages connected to the downstream ends of the exhaust ports of one cylinder or a plurality of cylinders whose exhaust order is not continuous with each other,
A throttle portion connected to the downstream end of each independent exhaust passage, and having a flow passage area at least downstream that is smaller than each upstream independent exhaust passage;
A collecting portion connected to a downstream end of the throttle portion, and the exhaust passages passing through the independent exhaust passages and the throttle portion are gathered inside;
A housing portion for housing the throttle portion and the collecting portion;
The throttle section includes one inner pipe connected so that the independent exhaust passages are close to each other, and an outer pipe fitted to the inner pipe so as to be relatively movable in the upstream and downstream directions on the upstream side. Prepared,
The gathering part is formed in a downstream part extending downstream of the outer pipe,
The inner pipe is provided so as to pass through a plurality of communication passages that allow the individual exhaust passages and the collecting portion to communicate with each other and a wall portion of the inner pipe, and between the upstream end and the downstream end of each communication passage. A plurality of communication ports for communicating the intermediate portion with a gap space formed between the inner tube and the outer tube;
When the outer tube moves to the closed position at the upstream moving end, the inner surface of the outer tube closes the communication port, the opening of the communication port is minimized, and the flow path area at the downstream end of the throttle portion is the minimum flow. On the other hand, when the outer pipe moves to the open position of the downstream moving end, the opening of the communication port is maximized, and the flow area of the throttle end downstream is the maximum flow area, By changing the amount of movement of the outer pipe in the upstream / downstream direction, the opening of the communication port is changed, and the flow passage area at the downstream end of the throttle portion can be changed,
As the flow path area at the downstream end of the throttle portion increases, a first clearance that increases along a first curve is formed between the inner surface of the outer tube and the outer surface of the inner tube. A second clearance that decreases along a second curve is formed between the outer surface and the inner surface of the housing portion;
The first curve and the second curve have an intersection where the clearance amounts of the first clearance and the second clearance become equal within a change range of the flow path area at the downstream end of the throttle portion,
The intake and exhaust of the internal combustion engine, wherein a flow path area at the downstream end of the throttle portion at an intersection of the first curve and the second curve is larger than an intermediate value between the minimum flow path area and the maximum flow path area. apparatus. In claim 1,
The inner pipe includes, on its outer peripheral surface, an inner pipe contact portion that contacts the inner peripheral surface of the outer pipe at the outer peripheral portion when the flow passage area at the downstream end of the throttle portion is the minimum flow passage area.
The outer tube includes an outer tube abutting portion that abuts the inner circumferential surface of the housing portion at the outer circumferential portion when the flow channel area at the downstream end of the throttle portion is the maximum flow channel area on the outer circumferential surface,
The first clearance is a clearance between an outer peripheral portion of the inner tube contact portion and an inner peripheral surface of the outer tube,
The intake / exhaust device for an internal combustion engine, wherein the second clearance is a clearance between an outer peripheral portion of the outer tube contact portion and an inner peripheral surface of the housing portion. In claim 2,
The outer peripheral portion of the inner tube abutting portion and the outer peripheral portion of the outer tube abutting portion are arcuate surfaces in which the axial section of the throttle portion is inclined so that the outer diameter increases toward the upstream side of the throttle portion. Is formed,
The outer peripheral surface of the outer tube and the outer peripheral surface of the outer tube contact portion are the outer peripheral portion of the inner tube contact portion and the outer peripheral portion of the outer tube contact portion, respectively. An exhaust system for an internal combustion engine, characterized by having an arcuate surface shape in which a corresponding contact portion is inverted so as to come into airtight contact with the inner surface. In any one of Claim 1 thru | or 3,
Channel area changing means capable of changing the channel area of the downstream end of the throttle part;
Valve driving means capable of driving the intake valve and the exhaust valve of each cylinder;
A control means capable of controlling the flow path area changing means and the valve driving means,
The control means includes
The flow path area changing means includes at least a high-speed and high-load region in which the engine speed of the internal combustion engine is higher than a preset reference speed and the load of the internal combustion engine is higher than a preset predetermined load. In the operating region, the flow passage area at the downstream end of the throttle is set to the maximum flow passage area, while the engine speed of the internal combustion engine is lower than the reference speed and the load of the internal combustion engine is higher than a predetermined load set in advance. In the second operation region including at least a high low speed and high load region, the flow passage area at the downstream end of the throttle portion is made smaller than the maximum flow passage area,
Due to the valve driving means, the valve opening period of the intake valve and the valve opening period of the exhaust valve of each cylinder overlap with each other by a predetermined overlap period, and the overlap of one cylinder is between cylinders in which the exhaust sequence is continuous. An intake / exhaust device for an internal combustion engine, wherein the intake valve and the exhaust valve of each cylinder are operated so that the period overlaps with the timing when the exhaust valve of the other cylinder is opened. In claim 4,
The intake / exhaust device for an internal combustion engine, wherein the control means causes the flow area at the downstream end of the throttle portion to be a minimum flow area in the second operation region by the flow area changing means. In claim 4 or claim 5,
The control means is characterized in that, by the flow path area changing means, the flow path area at the downstream end of the throttle portion is set to the minimum flow path area only when the engine speed of the internal combustion engine is on the low rotation side. An intake / exhaust device for an internal combustion engine.

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