JP2005147011A - Exhaust gas recirculation system for turbo supercharged engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation system capable of securely performing EGR even under high supercharging by a turbo charger. <P>SOLUTION: In this exhaust gas recirculation system for a turbo supercharged engine, an exhaust manifold of the engine equipped with the turbo charger is divided into a first exhaust manifold part and a second exhaust manifold part in each cylinder of which exhaust stroke is not overlapped, and an exhaust gas recirculation passage equipped with a check valve is connected between each of the exhaust manifold parts and an intake system of the engine. In each of the exhaust manifold parts, a nozzle part of which cross section gradually decreases toward an exhaust gas confluence part of a turbine housing is provided for a connection part of the both exhaust manifold parts and the turbine housing of the turbo charger. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust gas recirculation device for a turbocharged engine.

In order to reduce NOx (NOx) generated during combustion of a diesel engine, an exhaust gas recirculation device (EGR device) that recirculates exhaust gas (hereinafter referred to as “EGR”) to the intake side of the engine as an EGR gas today. It has been known.
Since NOx is produced by the reaction of oxygen and nitrogen in the air under high-temperature exhaust gas, this exhaust gas recirculation device lowers the combustion temperature with EGR and suppresses the generation of NOx.

Conventionally, many vehicles are equipped with a turbocharger for the purpose of improving engine output, and an exhaust gas recirculation device is also attached to a turbocharged engine equipped with a turbocharger.
The EGR of the turbocharged engine is performed using the pressure difference from the upstream side of the turbocharger turbine to the downstream side of the compressor. In the turbocharged engine, the supply air pressure is higher than the exhaust pressure. There is an operation region (especially a low speed and high load region), and there is a possibility that EGR cannot be sufficiently performed in this operation region.

Therefore, as an exhaust gas recirculation device for a turbocharged engine that solves such problems and enables EGR even in a high load range, those disclosed in Patent Document 1 and Non-Patent Document 1 are known.
Each of these exhaust gas recirculation devices is provided with one common venturi in a portion where the intake air of all cylinders flows, and EGR is performed on an intake manifold in which each cylinder is integrated. According to this structure, Since the intake pressure at the EGR junction becomes lower than the exhaust force due to the venturi effect, the flow velocity of the intake air passing through the throat increases, so the exhaust gas that is EGR from the EGR passage is pulled by the intake air that flows through the throat of the venturi. Will join.

As other EGR methods, an internal EGR method and a check valve type EGR method using exhaust pulsation are known.
In the internal EGR system, the exhaust valve closing timing is advanced so that a part of the exhaust gas remains in the combustion chamber and is mixed and combusted with the intake air. Recently, however, the exhaust valve is opened during the intake stroke, and the exhaust gas is exhausted. A method of introducing exhaust gas from the manifold side into the combustion chamber is also known as an internal EGR system.
JP 2002-221103 A Technical Review 2003 No. issued by Nissan Diesel Industry Co., Ltd. 15 Pages 18-24

However, as described above, the exhaust gas recirculation device disclosed in Patent Document 1 and Non-Patent Document 1 is provided with a common venturi for all the cylinders and is EGRed into an integrated intake manifold. There is a drawback (so-called intake interference) that intake negative pressure becomes small because intake pulsation is not used.
In order to increase the intake negative pressure and increase the EGR rate, the venturi throat must be squeezed greatly. As the throat is squeezed, the intake resistance increases, leading to a decrease in engine output and fuel consumption. was there.

Further, it has been pointed out that the above-described internal EGR system has a drawback that the exhaust gas temperature is high, so that the effect of reducing NOx cannot be sufficiently obtained.
On the other hand, in the check valve type EGR system, when the turbocharger mounted on the engine is a so-called “one-port” turbine inlet (exhaust gas confluence) like a variable nozzle turbocharger, the exhaust from the exhaust manifold When the gases merge together at the inlet of the turbine housing, the exhaust pulses in opposite phases cancel each other (so-called exhaust interference), and the check valve in the EGR passage does not operate effectively.

Moreover, as a result of the exhaust pulse being weakened in this way, it has been pointed out that the power of turning the turbine is weakened and the turbine efficiency is lowered.
The present invention has been devised in view of such circumstances, and solves the above-described problems, and the exhaust gas recirculation of a turbocharged engine that can perform EGR reliably even under high supercharging by a turbocharger. An object is to provide an apparatus.

  In order to achieve such an object, an exhaust gas recirculation device for a turbocharged engine according to claim 1 is configured such that an exhaust manifold of an engine provided with a turbocharger is connected to a first exhaust manifold portion for each cylinder whose exhaust strokes do not overlap each other. An exhaust gas recirculation passage having a check valve is connected between each exhaust manifold portion and the engine intake system, and the exhaust manifold portion and the turbine housing of the turbocharger are connected to each other. A nozzle portion whose cross section gradually decreases toward the exhaust gas merging portion of the turbine housing is provided for each exhaust manifold portion in the connection portion.

  According to a second aspect of the present invention, in the exhaust gas recirculation device for a turbocharged engine according to the first aspect, the nozzle portion directs the exhaust gas outlet side of each exhaust manifold portion toward the exhaust gas merging portion. The invention according to claim 3 is an exhaust gas recirculation device for a turbocharged engine according to claim 1 or 2, wherein A throttling portion is provided immediately downstream of the exhaust gas merging portion.

According to a fourth aspect of the present invention, in the exhaust gas recirculation device for a turbocharged engine according to the first or second aspect, a spacer is interposed at a connection portion between the two exhaust manifold portions and the turbine housing, The diaphragm is provided with a throttle portion.
Furthermore, the invention according to claim 5 is the exhaust gas recirculation device for the turbocharged engine according to claim 1, wherein a spacer is interposed in the connection portion between both the exhaust manifold portion and the turbine housing, and the spacer is attached to the spacer. The invention according to claim 6 is characterized in that, in the exhaust gas recirculation device for a turbocharged engine according to claim 5, a diffuser is disposed at an exhaust gas merging portion of the turbine housing. Features.

  According to a seventh aspect of the present invention, in the exhaust gas recirculation device for a turbocharged engine according to any one of the first to sixth aspects, the intake manifold of the turbocharged engine is provided with The two intake manifold sections are divided into a first intake manifold section and a second intake manifold section for each cylinder whose intake strokes do not overlap with each other, and an ejector is attached to each intake inlet, and the first intake manifold section An exhaust gas recirculation passage is connected between the ejector on the side and the first exhaust manifold portion, and between the ejector on the side of the second intake manifold portion and the second exhaust manifold portion.

  According to the invention according to each claim, the exhaust manifold is divided into a first exhaust manifold portion and a second exhaust manifold portion for each cylinder whose exhaust strokes do not overlap each other, and both the exhaust manifold portions and the turbine of the turbocharger are divided. Since the nozzle portion whose cross section gradually decreases toward the exhaust gas merging portion of the turbine housing is provided for each exhaust manifold portion at the connection portion with the housing, the exhaust pulse from the first exhaust manifold portion or the second exhaust manifold portion However, even if the inlet of the turbine housing of the turbocharger is “single”, the high-pressure exhaust pulse is transmitted to the check valve so that they do not escape to the second exhaust manifold part or the first exhaust manifold part. By operating, a high EGR rate is obtained and a high-pressure exhaust pulse is transmitted to the turbine. Te output because the turbine efficiency becomes good is improved, also it has the advantage that low NOx and low fuel consumption can be compatible with high EGR combinations by the check valve and a turbocharger 7.

  According to the inventions according to claim 3 and claim 4, the exhaust gas flowing out from each exhaust manifold portion to the exhaust gas merging portion of the turbocharger further increases the flow velocity at the throttle portion, and the invention according to claim 6 Since the exhaust gas from each exhaust manifold portion smoothly flows out to the exhaust gas merging portion by the diffuser, the exhaust pulse from the first exhaust manifold portion or the second exhaust manifold portion is changed to the second exhaust manifold portion or the second exhaust manifold portion. Escape to one exhaust manifold can be more reliably prevented, and the turbine efficiency is increased.

  In the invention according to claim 7, the intake manifold and the exhaust manifold are divided into cylinders whose intake and exhaust strokes do not overlap each other, and an exhaust gas recirculation passage fitted with a check valve is connected between them. Therefore, it has the advantage of preventing intake / exhaust interference, operating the check valve effectively using pulsation (intake / exhaust pulse), and further increasing the EGR rate even in a high load range where the boost pressure is high. Have.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 3 show a first embodiment of an exhaust gas recirculation apparatus according to claims 1 to 3, in which 1 is an in-line 6-cylinder diesel engine (hereinafter referred to as "engine"), 3 Is an exhaust manifold mounted on the engine 1, and the engine 1 has an ignition sequence of 1-4-2-6-3-5.

  Thus, the exhaust manifold 3 includes a first exhaust manifold portion 3a mounted on each cylinder where the exhaust strokes do not overlap each other, that is, on the # 1 to # 3 cylinders (front three cylinders) side, and # 4 to # 6. It is divided into a second exhaust manifold portion 3b mounted on the cylinder (rear three cylinders) side. Then, as shown in FIG. 2, the exhaust gas outlets 3a-1 and 3b-1 of both exhaust manifold portions 3a and 3b are partitioned by a partition wall 5 to be a variable nozzle type turbocharger (hereinafter referred to as “turbocharger”). The exhaust gas G flows out from the exhaust gas outlets 3a-1 and 3b-1 to the so-called "one-port" exhaust gas junction 11 of the turbine housing 9 alternately. It is like that.

  As shown in FIG. 2, the exhaust gas outlets 3 a-1 and 3 b-1 are tapered nozzle portions 13 and 15 whose cross sections gradually decrease toward the exhaust gas merging portion 11. The exhaust gas G exhausted from the # 3 cylinder side is made to flow out to the exhaust gas merging unit 11 at a higher speed by the nozzle unit 13, and the exhaust gas G exhausted from the # 4 to # 6 cylinder side is output from the nozzle unit 15. The flow rate is increased and the exhaust gas flows out to the exhaust gas merging portion 11. With this configuration, the exhaust pulse from the first exhaust manifold portion 3 a or the second exhaust manifold portion 3 b is sent to the second exhaust manifold portion 3 b or the second exhaust manifold portion 3 b. 1 The exhaust manifold portion 3a is prevented from escaping.

  Further, as shown in FIGS. 2 and 3, the turbine housing 9 is provided with a throttle portion 17 in which the downstream side of the exhaust gas merging portion 11 is narrowed in a venturi shape, and each of the exhaust gas flowing into the exhaust gas merging portion 11 is provided. The exhaust gas G from the exhaust manifold portions 3a and 3b is further discharged at a reduced speed through the exhaust passage 19 after rotating the turbine 7a in the turbine housing 7 by further increasing the flow velocity at the throttle portion 17, respectively. It has become.

As shown in FIG. 1, a compressor 7b is directly connected to the turbine 7a and is mounted in the intake passage 21, and the compressor 7b rotated by the turbine 7a compresses the intake air A so as to supercharge the compressed air A−. 1 is sent from the intake passage 21 to the engine 1 through the intake manifold 23.
As in the prior art, the intake passage 21 is provided with an intercooler 25 that lowers the temperature of the compressed air A-1 supercharged by the turbocharger 7 and improves the charging efficiency of the intake air, and is upstream of the compressor 7b. An air filter 27 is attached to the intake passage 21 on the side, and a silencer 29 is attached to the exhaust passage 19 on the downstream side of the turbine 7a.

EGR passages (exhaust gas recirculation passages) 31 and 33 are connected between the exhaust manifold 3 and an ejector 30 attached to the intake passage 21 on the downstream side of the intercooler 25.
The exhaust gas inlet of one EGR passage 31 is connected to the first exhaust manifold portion 3a, and the exhaust gas inlet of the other EGR passage 33 is connected to the second exhaust manifold portion 3b. In the EGR passage 31 and the EGR passage 33, EGR coolers 35 and 37 and check valves 39 and 41 are sequentially mounted from the exhaust manifold 3 side, but the downstream sides of both EGR passages 31 and 33 are joined together. An EGR valve 43 is mounted between the junction and the ejector 30.

The EGR gas flowing down the EGR passages 31 and 33 is pulled by the compressed air A-1 (intake air) flowing through the throat portion 30a of the ejector 30 and is EGRed into the intake manifold 23.
Since the exhaust gas recirculation device 45 according to the present embodiment is configured as described above, the compressed air A-1 supercharged by the turbocharger 7 passes through the intercooler 25 and the ejector 30 to the intake manifold 23 of the engine 1. The EGR gas that is supplied and flows into the EGR passages 31 and 33 by opening the check valves 39 and 41 is pulled by the compressed air A-1 flowing through the throat 30a of the ejector 30 and is then supplied to the intake manifold 23 by EGR. In addition, the EGR coolers 35 and 37 lower the temperature of the EGR gas flowing into the EGR passages 31 and 33 to suppress the deterioration of smoke during combustion to reduce NOx, and are attached to the EGR passages 31 and 33. The check valves 39 and 41 thus prevented prevent the backflow of EGR gas due to exhaust pulsation.

  As described above, in the present embodiment, the exhaust manifold 3 is divided into the first exhaust manifold portion 3a and the second exhaust manifold portion 3b for each cylinder in which the exhaust strokes do not overlap with each other. Tapered nozzle portions 13 and 15 whose cross sections gradually decrease toward the exhaust gas merging portion 11 at the exhaust gas outlets 3a-1 and 3b-1 of the connected first and second exhaust manifold portions 3a and 3b. In addition, since the venturi-shaped throttle portion 17 is provided immediately downstream of the exhaust gas merging portion 11 of the turbine housing 9, the exhaust gas G exhausted from the first exhaust manifold portion 3a speeds up the flow velocity at the nozzle portion 13. The exhaust gas G that has flowed out into the exhaust gas merging portion 11 and exhausted from the second exhaust manifold portion 3b side has its flow velocity increased by the nozzle portion 15, respectively. 11, the flow rate is further increased by the throttle unit 17 and flows down to the turbine 7a. The exhaust pulse from the first exhaust manifold unit 3a or the second exhaust manifold unit 3b is transferred to the second exhaust manifold unit 3b or the first There is no escape to the exhaust manifold portion 3a.

  Therefore, according to the present embodiment, even if the inlet of the turbine housing 9 of the turbocharger 7 is “one-port”, the high-pressure exhaust pulse is transmitted to the check valves 39 and 41 and they operate well so that the high EGR rate is increased. As a result, a high-pressure exhaust pulse is transmitted to the turbine 7a and the turbine efficiency is improved, so that the output is improved, and the combination of high EGR by the turbocharger 7 and the check valves 39 and 41 provides low NOx and low fuel consumption. Has the advantage of being compatible.

  FIG. 4 shows a cross-sectional view of the connecting portion between the exhaust manifold 3 and the turbocharger 7-1 of the exhaust gas recirculation apparatus according to one embodiment of the first, second and fourth aspects. In the above embodiment, FIG. As shown, the throttle portion 17 is provided in the turbine housing 9 itself immediately downstream of the exhaust gas merging portion 11. However, in this embodiment, an existing “one-port” turbocharger 7-1 is used, and the turbine housing 9-1 is used. In connecting the first and second exhaust manifold portions 3a and 3b to each other, a spacer 51 in which a venturi-shaped throttle portion 49 is formed in the exhaust passage 47 is interposed in the connection portion. In order to reduce exhaust resistance, the inner wall 53 of the inner wall 55 of the exhaust gas merging portion 11-1 of the turbine housing 9-1 and the exhaust gas outlets 3a-1, 3b- of the first and second exhaust manifold portions 3a, 3b are provided. 1 inner wall 57, 59 It is formed so as gently and continuously.

Since other configurations are the same as those of the embodiment of FIG. 1, the same components are denoted by the same reference numerals and description thereof is omitted.
Thus, also according to the present embodiment, the exhaust gas exhausted from the first exhaust manifold portion 3a side flows out to the exhaust gas merging portion 11 with the flow velocity increased by the nozzle portion 13 and also to the second exhaust manifold portion 3b side. The exhaust gas exhausted from the exhaust gas flows out into the exhaust gas merging unit 11-1 at the nozzle unit 15 at a higher flow rate, and further flows down to the turbine 7a-1 at the throttle unit 49 at a higher flow rate. The exhaust pulse from the part 3a or the second exhaust manifold part 3b does not escape to the second exhaust manifold part 3b or the first exhaust manifold part 3a.

  Therefore, even if the inlet of the turbine housing 9-1 of the turbocharger 7-1 is one, a high-pressure exhaust pulse is transmitted to the check valves 39 and 41 to obtain a high EGR rate, and a high-pressure exhaust is supplied to the turbine 7a-1. Since the pulse is transmitted and the turbine efficiency is improved, the output and fuel consumption are improved, and the combination of high EGR by the turbocharger 7-1 and the check valves 39 and 41 makes it possible to achieve both low NOx and low fuel consumption.

  FIG. 5 shows an embodiment of claims 1 and 5. In this embodiment, the exhaust manifold 61 is also divided into first exhaust manifold portion 61 a and second exhaust manifold portion 61 b for each cylinder whose exhaust strokes do not overlap each other. The exhaust gas outlets 61a-1 and 61b-1 are partitioned by a partition wall 63 and assembled and connected to the turbine housing 9-1 of the turbocharger 7-1. Is intervening.

In this embodiment, the exhaust gas outlets 61a-1 and 61b-1 are not tapered toward the exhaust gas merging portion 11-1 of the turbine housing 9-1. The nozzle portions 67 and 69 corresponding to the exhaust gas outlets 61a-1 and 61b-1 are provided.
In other words, the spacer 65 is provided with two exhaust passages 73 and 75 partitioned by a partition wall 71 coinciding with the partition wall 63 corresponding to the exhaust gas outlets 61a-1 and 61b-1. The exhaust passages 73 and 75 are tapered nozzle portions 67 and 69 whose cross sections gradually decrease toward the exhaust gas joining portion 11-1, and the inner walls 77 and 79 of the exhaust passages 73 and 75 are The inner wall 55 of the exhaust gas merging portion 11-1 and the inner walls 81 and 83 of the exhaust gas outlets 61a-1 and 61b-1 are formed so as to be smoothly continuous.

Since other configurations are the same as those of the embodiment of FIG. 1, the same components are denoted by the same reference numerals and description thereof is omitted.
Thus, according to the present embodiment, the exhaust gas exhausted from the first exhaust manifold 61a side is accelerated by the nozzle portion 67 and flows out to the exhaust gas junction 11-1, and the second exhaust manifold Since the exhaust gas exhausted from the portion 61b side is accelerated by the nozzle portion 69 and flows out to the exhaust gas merging portion 11-1, the exhaust pulse from the first exhaust manifold portion 61a or the second exhaust manifold portion 61b 2 No escape to the exhaust manifold portion 61b or the first exhaust manifold portion 61a.

Therefore, also in this embodiment, a high EGR rate is obtained by transmitting high-pressure exhaust pulses to the check valves 39 and 41, and a high-pressure exhaust pulse is transmitted to the turbine 7a-1 to improve turbine efficiency, so that the output is increased. In addition, the combination of high EGR with the turbocharger 7-1 and the check valves 39, 41 has the advantage that both low NOx and low fuel consumption can be achieved.
FIGS. 6 to 8 show an embodiment of the exhaust gas recirculation apparatus according to claims 1, 5 and 6, and this embodiment is the same as the embodiment of FIG. The exhaust manifold 61 and the turbocharger 7-1 are connected using a spacer 91 having two exhaust passages 87 and 89, and the exhaust passages 87 and 89 are connected to the exhaust gas junction 11-1 of the turbine housing 9-1. The nozzle sections 93 and 95 are tapered so that the cross section gradually decreases toward the end, but the total outlet area of the nozzle sections 93 and 95 is smaller than the flow path area of the exhaust gas merging section 11-1. Yes.

  In the vicinity of the jet port of the spacer 91, there are two opposing guide plates 97 and 99 which are inserted into the exhaust gas merging portion 11-1 and expand the exhaust gas from the nozzle portions 93 and 95 along therewith. A diffuser is attached, and by arranging the diffuser in the exhaust gas merging portion 11-1, the exhaust gas from each of the exhaust manifold portions 61a and 61b flows smoothly to the exhaust gas merging portion 11-1. It has become.

  Thus, according to the present embodiment, the exhaust gas from the exhaust manifold portions 61a and 61b smoothly flows out and expands to the exhaust gas merging portion 11-1 by the diffuser, and as a result, the first exhaust manifold portion 61a or Since the exhaust pulse from the second exhaust manifold portion 61b does not escape to the second exhaust manifold portion 61b or the first exhaust manifold portion 61a and the total pressure loss of the exhaust gas is reduced, the same as in the above-described embodiments. The purpose of the period can be achieved.

  FIG. 9 shows a second embodiment of the exhaust gas recirculation apparatus according to claims 1 to 3. The exhaust gas recirculation apparatus 101 according to the present embodiment replaces the variable nozzle type turbocharger 7 of FIG. A turbocharger 103 side turbine housing 9 connected to the exhaust manifold 3 (not shown) is connected to the turbine housing 9 of FIG. 2 using a two-stage turbocharger (two-stage turbocharger) 103, 105. It has the same structure.

A two-stage turbocharger is usually used to ensure high output with a small engine, and since one turbocharger has a limit on the compression ratio, a two-stage turbocharger is used to supercharge at a high pressure. It has become.
Since other configurations are the same as those of the embodiment of FIG. 1, the same components are denoted by the same reference numerals, and description thereof is omitted.

Thus, according to the present embodiment, as with the exhaust gas recirculation device 45 of FIG. 1, the intended purpose can be achieved, and the turbochargers 103 and 105 of the two-stage supercharging type can be supercharged at a high pressure. Since a large amount of intake air can be fed into the combustion chamber of the engine 1, particulates and NOx are reduced, and the output and fuel consumption are further improved.
FIG. 10 shows a first embodiment of the exhaust gas recirculation device according to claims 1 to 3 and claim 7. An exhaust gas recirculation device 107 according to this embodiment is replaced with an intake manifold 109 in place of the intake manifold 23 of FIG. Is divided into a first intake manifold portion 109a and a second intake manifold portion 109b for each cylinder in which the intake strokes do not overlap with each other corresponding to the first and second exhaust manifold portions 3a and 3b. EGR coolers are mounted between the ejector 111 throat portion 111a and the first exhaust manifold portion 3a, and between the ejector 113 throat portion 113a and the second exhaust manifold portion 3b. 35, 37, check valves 39, 41, and EGR valves 115, 117 are sequentially mounted from the exhaust manifold 3 side. It is obtained by connecting the R channel 19, 12.

Since other configurations are the same as those of the embodiment of FIG. 1, the same components are denoted by the same reference numerals and description thereof is omitted.
Thus, according to the present embodiment, as shown in FIG. 11, between the first intake manifold portion 109a and the first exhaust manifold portion 3a, and between the second intake manifold portion 109b and the second exhaust manifold portion 3b. Since the timing of each exhaust pulse (positive pressure) peak and intake pulse (negative pressure) valley substantially coincides with each other, a large differential pressure ΔP is generated on both sides of each of the EGR passages 119 and 121, and the check valve 39 and 41 function more satisfactorily, and more reliable EGR can be performed even under supercharging by the turbocharger 7.

  However, as described above, the intake manifold 109 is divided into the first intake manifold portion 109a and the second intake manifold portion 109b for each cylinder in which the intake strokes do not overlap with each other. During the intake period of each cylinder, the valves of the other cylinders do not open and intake interference does not occur, and the intake pulse generated in the intake stroke is transmitted as pressure waves to the respective ejectors 111 and 113. The EGR gas is introduced from the EGR passages 119 and 121 into the portions where the flow velocity increases at the throat portions 111a and 113a of the 111 and 113 and the positive pressure of the intake air decreases.

As described above, according to the present embodiment, the intake manifold 109 and the exhaust manifold 3 are divided for each cylinder in which the intake and exhaust strokes do not overlap each other, so that intake and exhaust interference can be prevented and pulsation (intake and exhaust pulses) is generated. Since the check valves 39 and 41 can be operated effectively, there is an advantage that a higher EGR rate can be obtained as compared with the exhaust gas recirculation device 45 of FIG.
FIG. 12 shows a second embodiment of the exhaust gas recirculation device according to claims 1 to 3 and claim 7, and the exhaust gas recirculation device 123 according to this embodiment is replaced with the turbocharger 7 of FIG. The two-stage supercharging turbochargers 103 and 105 described in the exhaust gas recirculation apparatus 101 are used, and other configurations are the same as those in the embodiment of FIG. Their description is omitted.

  Thus, according to the present embodiment, as in the embodiment of FIG. 10, not only the intended purpose can be achieved, but also supercharging at a high pressure is performed by the two-stage turbochargers 103 and 105. Since a large amount of intake air can be sent into the combustion chamber, there is an advantage that particulates and NOx are reduced, and output and fuel consumption are further improved.

It is explanatory drawing of the exhaust gas recirculation apparatus which concerns on 1st embodiment of Claim 1 thru | or 3. It is a principal part expanded sectional view of the connection part of a turbocharger and an exhaust manifold. It is a principal part expanded sectional view of the connection part of a turbocharger and an exhaust manifold. FIG. 5 is an enlarged cross-sectional view of a main part of a connection portion between an exhaust manifold and a turbocharger of an exhaust gas recirculation apparatus according to one embodiment of claim 1, claim 2, and claim 4. FIG. 7 is an enlarged cross-sectional view of a main part of a connection portion between an exhaust manifold and a turbocharger of an exhaust gas recirculation apparatus according to one embodiment of claim 1 and claim 5. FIG. 6 is an enlarged cross-sectional view of a main part of a connection portion between an exhaust manifold and a turbocharger of an exhaust gas recirculation apparatus according to one embodiment of claim 1, claim 5 and claim 6. It is a principal part expanded sectional view of the connection part of an exhaust manifold and a turbocharger. It is a perspective view of the connection part of an exhaust manifold and a turbocharger. It is explanatory drawing of the exhaust gas recirculation apparatus which concerns on 2nd embodiment of Claim 1 thru | or 3. It is explanatory drawing of the exhaust gas recirculation apparatus which concerns on 1st embodiment of Claim 1 thru | or Claim 3 and Claim 7. It is a wave form diagram of an exhaust pulse and an intake pulse. It is explanatory drawing of the exhaust gas recirculation apparatus which concerns on 2nd embodiment of Claim 1 thru | or Claim 3 and Claim 7.

Explanation of symbols

1 Engine 3, 61 Exhaust manifolds 3a, 61a First exhaust manifold portions 3b, 61b Second exhaust manifold portions 3a-1, 3b-1, 61a-1, 61b-1 Exhaust gas outlets 7, 7-1, 103, 105 Turbocharger 9, 9-1 Turbine housing 11, 11-1 Exhaust gas confluence 13, 13, 67, 69, 93, 95 Nozzle 17, 49 Throttle 23, 109 Intake manifold 25 Intercooler 30, 111, 113 Ejectors 30a, 111a, 113a Throat portions 31, 33, 119, 121 EGR passages 35, 37 EGR coolers 39, 41 Check valves 43, 115, 117 EGR valves 45, 101, 107, 123 Exhaust gas recirculation devices 51, 65, 91 Spacers 73, 75, 87, 89 Exhaust flow path 97, 99 Guide plate 109a First intake manifold Part 109b second intake manifold part

Claims (7)

  An exhaust manifold of an engine equipped with a turbocharger is divided into a first exhaust manifold portion and a second exhaust manifold portion for each cylinder whose exhaust strokes do not overlap each other. An exhaust gas recirculation passage provided with a check valve is connected between them, and a nozzle whose cross section gradually decreases toward the exhaust gas merging portion of the turbine housing at the connection portion between the two exhaust manifold portions and the turbine housing of the turbocharger. An exhaust gas recirculation device for a turbocharged engine, wherein a portion is provided for each exhaust manifold portion.   2. The turbocharged engine according to claim 1, wherein the nozzle portion is provided such that an exhaust gas outlet side of each exhaust manifold portion gradually decreases in cross section toward the exhaust gas merging portion. Exhaust gas recirculation device.   The exhaust gas recirculation device for a turbocharged engine according to claim 1 or 2, wherein a throttle portion is provided immediately downstream of the exhaust gas merging portion of the turbine housing.   The exhaust gas recirculation device for a turbocharged engine according to claim 1 or 2, wherein a spacer is provided at a connection portion between both exhaust manifold portions and the turbine housing, and a throttle portion is provided in the spacer.   2. The exhaust gas recirculation device for a turbocharged engine according to claim 1, wherein a spacer is provided at a connection portion between the two exhaust manifold portions and the turbine housing, and a nozzle portion is provided in the spacer.   6. The exhaust gas recirculation device for a turbocharged engine according to claim 5, wherein a diffuser is disposed at an exhaust gas merging portion of the turbine housing.   The turbocharged engine intake manifold is divided into a first intake manifold portion and a second intake manifold portion for each cylinder in which the intake strokes do not overlap each other corresponding to the first and second exhaust manifold portions, At the same time, an ejector is mounted at each intake inlet, and between the ejector on the first intake manifold section side, the first exhaust manifold section, the ejector on the second intake manifold section side, and the second exhaust manifold section, respectively. The exhaust gas recirculation device for a turbocharged engine according to any one of claims 1 to 6, wherein an exhaust gas recirculation passage is connected.

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