JP6551046B2 - engine - Google Patents

Description

  The present invention relates to an engine, particularly to a turbocharger and an EGR device.

  There is an engine provided with a turbocharger composed of a turbine and a compressor, and an EGR device that circulates part of the exhaust gas as EGR gas from an exhaust pipe downstream of the turbine to an intake pipe upstream of the compressor (see Patent Document 1). . In this engine, the EGR cooler is attached to the opposite side of the turbocharger.

JP 2011-69252 A

By the way, in the EGR device, the differential pressure across the EGR valve runs short on the low load side in the EGR region. For this reason, a normally-open differential pressure device is provided in the intake pipe upstream of the EGR gas discharge port, and the differential pressure device is closed on the low load side in the EGR region. By increasing the differential pressure across the EGR valve by this amount of closure, the differential pressure across the EGR valve is secured. As described above, when the differential pressure device is provided in the intake pipe upstream from the EGR gas discharge port, the following two problems arise. That is,
(1) Warm up the differential pressure device early when the engine is cold started,
(2) To avoid overheating of the differential pressure device during high load operation of the engine.

  However, the technique of Patent Document 1 does not describe any of these problems.

  Therefore, an object of the present invention is to provide an engine capable of achieving both the early warm-up of the differential pressure device at the time of engine cold start and the overheat avoidance of the differential pressure device at the time of high engine load.

The engine of the present invention includes, as a premise, an intake system component, an exhaust system component, a turbocharger, an EGR device, and a differential pressure device. The intake system component comprises an intake pipe through which intake air flows introduced into an engine block having a cylinder row, an intake manifold connected to the intake pipe for distributing the intake air, and an air cleaner provided at the upstream end of the intake pipe . The exhaust system component includes an exhaust pipe through which gas exhausted from the engine block flows. The turbocharger is composed of a turbine provided in the exhaust pipe and a compressor provided in the intake pipe. The EGR device has an EGR passage, an EGR valve, and an EGR gas cooling device. The EGR passage is a passage through which EGR gas flows, and communicates an exhaust pipe downstream of the turbine and an intake pipe upstream of the compressor. The EGR valve opens and closes the EGR passage. The EGR gas cooling device cools the EGR gas upstream of the EGR valve. The differential pressure device is provided in an intake pipe upstream from the EGR gas discharge port. In the engine of the present invention, when the engine block is viewed from above, the intake manifold is orthogonal to the cylinder row direction and the intake manifold is orthogonal to the cylinder row direction centering on the cylinder row of the engine block. The exhaust system component and the turbocharger are arranged on the other side in the direction. Further, in the engine of the present invention, a vertical space is provided between the exhaust system parts, and the differential pressure device is provided at a position where the exhaust system parts and the differential pressure device overlap when viewed from above, The EGR gas cooling device is provided so as to pass through a space between the exhaust system component and the differential pressure device and to be interposed between the differential pressure device and the exhaust system component.

  Since the EGR gas cooling device functions as an exhaust system component at the time of cold start of the engine, the radiation heat of the exhaust gas from the EGR gas cooling device can warm up the differential pressure device early. Since the icing of the operating device is eliminated before the engine warm-up is completed when the engine is cold started, the low-pressure EGR device can be operated immediately after the engine warm-up is completed. Due to the icing of the operating device, the fuel efficiency can be improved compared to the case where the low pressure EGR device cannot be operated immediately after the engine warm-up is completed. In addition, since the differential pressure device can be warmed up promptly by changing the layout of parts, the hot water piping system for preventing differential pressure device freezing can be eliminated. On the other hand, when the engine is heavily loaded, the radiant heat of the exhaust from the exhaust system parts is greater than immediately after the engine is cold started. For this reason, since the radiant heat of the exhaust from the exhaust system components directly hits the differential pressure device, the differential pressure device is exposed to a high temperature. In this case, since the EGR gas cooling device is interposed between the differential pressure device and the exhaust system component, the EGR gas cooling device shuts off the radiation heat from the exhaust system component to the differential pressure device. The radiant heat of the exhaust from the exhaust system components that collide with the EGR gas cooling device does not reach the differential pressure device. Thus, overheating of the differential pressure device can be avoided by blocking the radiant heat of the exhaust from the exhaust system components by the EGR gas cooling device. In addition, the temperature of the entire EGR gas cooling device is maintained at a temperature lower than that of the exhaust system components by the heat absorption effect of the circulating refrigerant inside the EGR gas cooling device. As a result, an increase in the atmospheric temperature of the differential pressure device is suppressed, so that the influence of the radiant heat of the exhaust can be mitigated at a high engine load. Thus, according to the present invention, the differential pressure device can be warmed up early by the radiant heat of the exhaust gas from the EGR gas cooling device at the time of cold start of the engine, and the EGR gas cooling device can radiate the radiant heat of the exhaust gas from the exhaust system parts at a high engine load. The overpressure of the differential pressure device can be avoided.

1 is a schematic configuration diagram of an engine system according to a first embodiment of the present invention. It is the whole view which looked at the horizontal engine of a 1st embodiment from the top. It is the whole view which looked at the transverse engine of a 1st embodiment from the vehicles back side. It is a longitudinal cross-sectional view in alignment with the flow of the suction | inhalation air of a differential pressure device and its downstream intake pipe. It is sectional drawing orthogonal to the flow of the intake air which looked at the butterfly valve of the differential pressure device from the downstream of the flow.

  Hereinafter, embodiments of the present invention will be described based on the drawings.

First Embodiment
FIG. 1 is a schematic configuration diagram of an engine system according to a first embodiment of the present invention. The engine system is outlined above using FIG.

  The engine 1 is a gasoline engine and is mounted on a vehicle (not shown). The engine 1 includes an intake passage 4 and an exhaust passage 11. The intake passage 4 includes an intake pipe 4a, an intake collector 4b, and an intake manifold 4c.

  The intake pipe 4a immediately upstream of the intake collector 4b is provided with an electronically controlled throttle device 5 responsive to the amount of depression of the accelerator pedal. The throttle device 5 includes a throttle body 6, a valve body disposed inside the throttle body 6, and an actuator 8 for driving the valve body. Inside the throttle body 6, for example, a butterfly valve 7 as a valve body is arranged. A motor (rotating electric machine) 8 as an actuator is attached to the outer periphery of the throttle body 6.

  The intake air is metered by the throttle device 5 through the intake pipe 4a. The measured air is stored in the intake collector 4b, and distributed and supplied from the intake collector 4b to the cylinders 9 (combustion chambers) of the cylinders via the intake manifold 4c. Although the embodiment is an electronically controlled throttle device, the throttle valve and the accelerator pedal may be connected by a wire.

  A fuel injection valve 47 is provided in the intake manifold 4c and an ignition plug 48 directly faces the cylinder 9, and fuel is injected from the fuel injection valve 47 into the intake manifold 4c (intake port). The injected fuel is mixed with the air regulated by the throttle device 5 to form a gas, which is ignited and burned by the spark plug 48. The burning gas is discharged into the exhaust passage 11 after performing the work of pushing down the piston 10. The position where the fuel injection valve 47 is provided is not limited to the intake manifold. The fuel injection valve may be provided directly facing the cylinder 9.

  The exhaust passage 11 includes an exhaust manifold 11a into which exhaust gas from the cylinders 9 of the respective cylinders flows, and an exhaust pipe 11b connected to a collecting portion of the exhaust manifold 11a. Since exhaust contains harmful three components of HC, CO and NOx, the exhaust pipe 11b is provided with the manifold catalyst 12 and the exhaust pipe 11b downstream thereof is provided with the main catalyst 13 in order to purify all of them. The main catalyst 13 is provided, for example, under the floor of the vehicle. Each of these catalysts 12 and 13 is composed of, for example, a three-way catalyst. A muffler 29 is provided at the end of the exhaust pipe 11b.

  The engine 1 further includes a turbocharger 21. The turbocharger 21 includes a turbine 22 provided in the exhaust pipe 11b, a compressor 25 provided in the intake pipe 4a, and a shaft 28 connecting the turbine 22 and the compressor 25. The turbine 22 mainly includes a turbine housing 23 and a turbine wheel 24. The turbine wheel 24 is disposed inside the turbine housing 23. On the other hand, the compressor 25 mainly includes a compressor housing 26 and a compressor wheel 27, and the compressor wheel 27 is disposed inside the compressor housing 26.

  The turbine 22 is rotated by the energy of the exhaust gas flowing through the exhaust pipe 11b, and drives a compressor 25 coaxial with the turbine 22. The compressor 25 compresses the intake air taken in via the air cleaner 47. The compressed air that is compressed and exceeds the atmospheric pressure is sent to the intake collector 4b. By operating the turbocharger 21, it is possible to obtain the target boost pressure.

  The turbocharger 21 is provided with a bypass passage 41 bypassing the turbine 22 and a normally closed waste gate valve 42 opening and closing the bypass passage 41. The waste gate valve 42 includes a main body 43 as a housing, a valve body disposed inside the main body 43, and an actuator for driving the valve body. For example, a swing valve 44 as a valve body is disposed inside the main body. A motor (rotating electric machine) 45 as an actuator is attached to the outer periphery of the main body 43.

  For example, when the actual boost pressure detected by the boost pressure sensor becomes higher than the target boost pressure, by driving the motor 45, the waste gate valve 42 is opened and a part of the exhaust gas flowing into the turbine 22 is The turbine 22 is bypassed to flow. As a result, the turbine rotation speed is lowered before the waste gate valve 42 is opened, and the compressor rotation speed coaxial with the turbine 22 is also lowered. When the compressor rotational speed decreases, the actual boost pressure decreases and matches the target boost pressure. The opening degree of the waste gate valve 42 is held at the timing when the actual boost pressure matches the target boost pressure.

  The intake collector 4b includes a water-cooled intercooler 51. The intercooler 51 is for cooling the air compressed by the compressor 25 with the cooling water flowing through the cooling water passage. Specifically, the intercooler 51 is composed of a cooling water passage and an air passage provided on the outer periphery thereof. The cooling water passage of the intercooler 51 and the air-cooled sub radiator 52 are connected by cooling water passages 53 and 54. For example, the sub-radiator 52 is arranged in series with a radiator for cooling engine coolant so that the traveling wind passes therethrough. The coolant passage 53 is provided with a pump 55 for circulating the coolant.

  In the sub radiator 52, the cooling water carried from the intercooler 51 is cooled by traveling wind. The cooling water cooled by the sub radiator 52 is guided to the intercooler 51. The intercooler 51 exchanges heat between the air whose temperature has been increased by the air compression by the compressor 25 and the cooling water flowing through the cooling water passage to cool the air. The air whose temperature has been increased by the air compression by the compressor 25 is cooled by the intercooler 51, whereby the supercharging efficiency can be increased.

  Also in the engine 1 provided with the turbocharger 21, a rope lesser loop EGR device (hereinafter referred to as “low pressure EGR device”) 14 is provided in order to suppress knocking in the supercharging region. The low pressure EGR device 14 includes an EGR passage 15, an EGR cooler 16 interposed in the EGR passage 15, and an EGR valve 17 for opening and closing the EGR passage 15.

  The EGR valve 17 includes a main body 18 as a housing, a normally closed valve body disposed inside the main body 18, and an actuator for driving the valve body. For example, a butterfly valve 19 as a valve body is disposed inside the main body 18. A motor (rotating electric machine) 20 as an actuator is attached to the outer periphery of the main body 18.

  The EGR passage 15 is branched from the exhaust pipe downstream of the turbine 22, specifically, the exhaust pipe 11 b between the manifold catalyst 12 and the main catalyst 13, and merges with the intake pipe 4 a upstream of the compressor 23.

  An operating region in which the EGR valve 17 is opened is set in advance as an EGR region, and when the operating point of the engine enters the EGR region, the EGR valve 17 is opened. As a result, the exhaust pipe 11 b downstream of the turbine 22 and the intake pipe 4 a upstream of the compressor 25 are communicated via the EGR passage 15. At this time, a gas (a part of the exhaust gas) flows through the EGR valve 17 by a differential pressure between the exhaust pipe pressure downstream of the turbine and the intake pipe pressure upstream of the compressor. Since the differential pressure between the exhaust pipe pressure downstream of the turbine and the intake pipe pressure upstream of the compressor is as small as about 1 kPa, for example, it is called a low pressure EGR device.

  A part of the exhaust gas flowing from the exhaust pipe 11b to the EGR passage 15 is referred to as “EGR gas”. Further, since the EGR gas is taken out from the exhaust pipe 11b to the EGR passage 15, the opening end of the EGR passage 15 to the exhaust pipe 11b is referred to as an “EGR gas outlet”. The symbol A is attached to the EGR gas outlet. Since the EGR gas is discharged from the EGR passage 15 to the intake pipe 4a, the opening end of the EGR passage 15 to the intake pipe 4a is referred to as "EGR gas discharge port". The symbol B is attached to the EGR gas discharge port.

  The EGR cooler 16 is water-cooled and is provided in the EGR passage 15 upstream of the EGR valve 17. The water-cooled EGR cooler 16 cools EGR gas with cooling water. For this reason, the cooled EGR gas flows through the EGR valve 17 in the EGR region. Although the cooling target of the EGR cooler 16 is EGR gas, the cooling target of the intercooler 51 is different in that it is air containing EGR gas. However, the configuration itself is different between the EGR cooler 16 and the intercooler 51. There is not much difference between the two. For this reason, the detailed description about the EGR cooler 16 is omitted.

  In the low pressure EGR device 14, the differential pressure across the EGR valve 17 becomes small particularly in the low load side of the EGR region, and the EGR gas can not be sufficiently discharged from the EGR gas discharge port B to the intake pipe 4a. In order to cope with this, the differential pressure device 50 is provided in the intake pipe 4a upstream of the EGR gas discharge port B. The differential pressure device 50 includes a main body 51 as a housing, a normally open valve body disposed in the main body 51, and an actuator for driving the valve body. For example, a butterfly valve 52 as a valve body is disposed inside the main body 51. A motor (rotating electric machine) 53 as an actuator is attached to the outer periphery of the main body 51.

  In the EGR region, the low load side region is set in advance as a differential pressure device operating range, and when the engine operating point enters the differential pressure device operating range, the differential pressure device 50 moves from the fully open position to a predetermined opening. It is closed. As a result, the pressure of the intake air at the EGR gas discharge port B is smaller than when the differential pressure device 50 is in the fully open position. The differential pressure across the EGR valve 17 is increased by the decrease, and the amount of EGR gas discharged from the EGR gas discharge port B is increased. This is because the amount of EGR gas discharged from the EGR gas discharge port B is proportional to the opening area of the EGR valve 17 and the differential pressure across the EGR valve 17, so when the differential pressure across the EGR valve 17 becomes large, This is because the amount of EGR gas discharged from the EGR gas discharge port B increases. Thus, by operating the differential pressure device 50 in the region on the low load side in the EGR region, the differential pressure across the EGR valve 17 is secured.

  Furthermore, a bypass passage 31 that bypasses the compressor 23 is provided. A recirculation valve 32 is provided in the bypass passage 31. The recirculation valve 32 includes a main body 33 as a housing, a valve body disposed inside the main body 33, and an actuator for driving the valve body. For example, a butterfly valve 34 as a valve body is disposed inside the main body 33. A motor (rotating electric machine) 35 as an actuator is attached to the outer periphery of the main body 33.

  When the throttle device 5 is closed to decelerate the vehicle, the valve 32 recirculates pressurized air trapped in the intake pipe 4a from the throttle device 5 to the compressor 25 to the upstream side of the compressor 25 (recirculation). It is for making it happen. On the other hand, when supercharging is performed by the turbocharger 21 in an operating range other than when the vehicle is decelerating, the valve 32 is basically fully closed and air on the upstream side of the compressor 25 (including EGR gas ) Are led to the compressor 25.

  The engine 1 is a so-called landscape engine that is placed horizontally on a vehicle. That is, the engine 1 is mounted such that the crankshaft is positioned in the direction perpendicular to the front-rear direction of the vehicle. And since the vehicle is a front-wheel drive vehicle, the engine 1 is mounted in front of the vehicle. This completes the overview of the engine system.

  FIG. 2 is an overall view of the above-described horizontal engine 1 viewed from above, and FIG. 3 is an overall view of the above-described horizontal engine 1 viewed from the vehicle rear side. However, in FIG. 2 and FIG. 3, the description of the engine parts not related to the present invention is omitted from the engine parts shown in FIG.

  Conversely, FIGS. 2 and 3 show the air cleaner 47 to the compressor 25, the intake collector 4b, the intake system parts of the intake manifold 4c, and the exhaust system parts from the exhaust manifold 11a to the manifold catalyst 12. These other components are the low pressure EGR device 14, the turbocharger 21, and the differential pressure device 50. And the main part of the present invention is in the layout (arrangement) of these parts.

  Here, when a component through which the exhaust gas passes is defined as an "exhaust system component", the exhaust system component includes an exhaust manifold 11a, an exhaust pipe 11b, a manifold catalyst 12, and a low pressure EGR device 14. In this case, the temperature of the exhaust system components other than the low pressure EGR device 14 increases as the exhaust heat increases. However, since the coolant water flows inside the water-cooled EGR cooler 16, the exhaust heat is Although the temperature rises as it increases, it does not rise above a certain temperature. In other words, the water-cooled EGR cooler 16 has an endothermic effect due to the internal circulating cooling water. The EGR valve 17 adjacent to the downstream side of the EGR cooler 16 is also thermally similar to the EGR cooler 16. Therefore, in this embodiment, the low-pressure EGR device 14 is not included in the exhaust system parts. Further, since the exhaust manifold 11a, the exhaust pipe 11b, and the manifold catalyst 12 occupy a large thermal mass, in the following, the exhaust system parts mainly mean these three (11a, 11b, 12). It shall be. It is not always essential to provide the catalyst 12. When the catalyst 12 is not provided, the exhaust manifold 11a and the exhaust pipe 11b (that is, the exhaust passage 11) occupy the thermally large mass.

  In order to simplify the description, it is assumed that the transversely mounted engine 1 shown in FIGS. 2 and 3 is substantially upright. Engine 1 is, for example, an in-line four-cylinder engine. The position of the see-through cylinder is shown by a broken line in FIG. 2 and each cylinder is assigned a cylinder number, but each cylinder can not be seen directly. Since it is an inline engine, four cylinders are arranged in a line.

  The whole of the cylinder block, the cylinder head provided on the upper part of the cylinder block, and the valve operating mechanism provided on the upper part of the cylinder head is defined as an “engine block”. And the engine block 61 is simplified and described in the rectangular parallelepiped. Here, the cylinder head cover provided at the top of the cylinder head is assumed to be included in the cylinder head. In order to improve appearance and quietness, an engine cover may be provided on the upper part of the cylinder head cover. When the engine cover is provided, the engine cover is also included in the cylinder head. In short, the cylinder head cover is the upper surface 61d of the engine block 61 when the engine cover is not provided, and the engine cover is the upper surface 61d of the engine block when the engine cover is provided. In FIG. 2, the left-right direction is the cylinder row direction of the engine block 61, the right side in the cylinder row direction is the front side of the horizontally placed engine 1, and the left side in the cylinder row direction is the rear side of the horizontally placed engine 1.

  When the engine 1 is viewed from above, the intake system components are on the vehicle rear side on the side surface 61a on the vehicle front side (one side in the direction orthogonal to the cylinder column direction) with the cylinder row of the engine block 61 as the center. Exhaust system components are disposed on the side surface 61 b (the other side in the direction orthogonal to the cylinder row direction). Hereinafter, the side surface of the engine block 61 on the vehicle front side is simply referred to as “vehicle front side surface”. The side surface of the engine block 61 on the vehicle rear side is simply referred to as “vehicle rear side surface”. That is, when the horizontally mounted engine 1 is viewed from above, as shown in FIG. 2, the intake collector 4b and the intake manifold 4c are attached to the vehicle front side surface 61a, and the exhaust manifold 11a is attached to the vehicle rear side surface 61b. The exhaust manifold 11a is positioned horizontally above the vehicle rear side surface 61b as shown in FIG. 3 when the horizontally mounted engine 1 is viewed from the vehicle rear side.

  As described above, the layout in which the intake system components are arranged on the front side of the vehicle and the exhaust system components are arranged on the rear side of the horizontal engine 1 is referred to as “front intake / rear exhaust layout”. On the other hand, the layout in which the intake system parts are arranged on the rear side of the vehicle and the exhaust system parts are arranged on the front side of the vehicle in the horizontally mounted engine 1 is referred to as “front exhaust / rear intake layout”. In this embodiment, although the case of the front intake / rear exhaust layout is described, the present invention can be applied to the front exhaust / rear intake layout. The transmission 62 is connected to the rear surface 61 c of the engine block 61.

  When the transversely-mounted engine 1 is viewed from the rear side of the vehicle, a turbocharger 21 is provided below the exhaust manifold 11 a on the rear side 61 b of the vehicle. In this case, in order to arrange the air cleaner 47 and the compressor 25 on the opposite side of the engine block 61 in the cylinder row direction, the compressor 25 is arranged on the engine front side in the cylinder row direction, and the turbine 22 is arranged on the engine rear side in the cylinder row direction.

  When the horizontally mounted engine 1 is viewed from the rear side of the vehicle, the manifold catalyst 12 is provided next to the rear side of the turbine 22 in the cylinder row direction, and the outlet of the turbine 22 and the inlet of the manifold catalyst 12 are connected by the exhaust pipe 11b. When the manifold catalyst 12 has a cylindrical shape, it is provided in the horizontal direction as shown in FIG. 3 when the horizontally placed engine 1 is viewed from the rear side of the vehicle.

  An intake pipe 4a is connected to the inlet of the compressor 25 on the front side of the engine in the column direction. When the transversely mounted engine 1 is viewed from the rear side of the vehicle, the intake pipe 4a connected to the inlet of the compressor 25 as shown in FIG. After bending, the intake pipe 4a is provided to extend above the upper surface 61d of the engine block toward the rear side of the engine in the cylinder row direction. The upstream end of the intake pipe 4a is extended to a position slightly beyond the rear surface 61c of the engine block 61, and an air cleaner 47 is provided at the upstream end of the intake pipe 4a. Thus, the distance between the air cleaner 47 and the compressor 25 is secured.

  The reason why the air cleaner 47 and the compressor 25 are arranged on the opposite side of the engine block 61 in the cylinder row direction is as follows. That is, when the position of the EGR gas discharge port B is too close to the compressor 25, the EGR gas having a high temperature flows into the compressor 25 without being sufficiently diffused in the intake pipe 4a up to the compressor 25. As a result, non-uniformity (non-uniformity) of the thermal expansion of the compressor housing 26 occurs. Then, the clearance between the compressor wheel 27 and the compressor housing 26 becomes uneven, so the efficiency of the compressor 25 is reduced. On the other hand, when the position of the EGR gas discharge port B is close to the differential pressure device 50, there is a concern that the differential pressure device 50 may be contaminated by blowing back EGR gas when the engine is stopped. In order to avoid such a situation, the EGR gas is discharged so that the EGR gas discharged from the EGR gas discharge port B sufficiently diffuses into the intake air (fresh air) in the intake pipe 4a and then flows into the compressor 25. This is to increase the pipe distance of the intake pipe 4a from the outlet B to the compressor 25. Further, in order to prevent the differential pressure device 50 from being contaminated by the blow-back of EGR gas when the engine is stopped, the pipe distance of the intake pipe 4a between the differential pressure device 50 and the EGR gas discharge port B is increased. Therefore, the air cleaner 47 and the compressor 25 are arranged on the opposite side of the engine block 61 in the cylinder row direction so that the pipe distance of the intake pipe from the differential pressure device 50 to the compressor 25 is ensured.

  And, the intake pipe 4a connecting the air cleaner 47 and the compressor 25 is disposed above the upper surface 61d of the engine block 61 and on the exhaust system component side when the engine 1 is viewed from above. That is, the air cleaner 47 and the compressor 25 are extended above the upper surface 61 d of the engine block and above the part where the exhaust system components are attached with a predetermined space left toward the engine rear side in the cylinder row direction. Is provided. The intake pipe connecting the air cleaner 47 and the compressor 25 is hereinafter referred to as a “compressor upstream intake pipe”. As shown in FIG. 3, a differential pressure device 50 is provided at a position almost directly above the compressor upstream intake pipe 4a with a predetermined space between the exhaust system parts and the above space. An EGR cooler 16 is provided.

  Here, if the compressor upstream side intake pipe 4a is described in FIG. 2, the positional relationship with the exhaust system parts arranged below the intake pipe 4a becomes unclear. Therefore, in FIG. 2, the compressor upstream side intake pipe 4a is indicated by a virtual line (broken line) so that the positional relationship with the exhaust system parts (11a, 11b, 12) becomes clear. That is, the exhaust manifold 11a is attached to the vehicle rear side surface 61b. Further, the turbocharger 21, the exhaust pipe 11 b and the manifold catalyst 12 are provided substantially in line and in parallel with the cylinder row of the engine block 61 so as to project from the exhaust manifold 11 a to the rear side of the vehicle. Then, an intake pipe 4a connecting the air cleaner 47 and the compressor 25 is positioned above substantially the center of the entire exhaust manifold 11a, the exhaust pipe 11b and the manifold catalyst 12 (see a broken line in FIG. 2). The differential pressure device 50 is present in the upper part of the position which is applied to both a part of the center of the exhaust manifold 11 a and a part of the manifold catalyst 12 in FIG. The EGR cooler 16 and the EGR valve 17 can be seen below the differential pressure device 50, and the EGR cooler 16 is disposed in the space in the vertical direction between the differential pressure device 50 and the exhaust system parts (11a, 11b, 12) You can see that

  The reason for providing the differential pressure device 50 at a position almost right above the compressor intake-side intake pipe 4a and a predetermined space with the exhaust system components and for providing the EGR cooler 16 in the above space is as follows: It is street. That is, in the case of the low-pressure EGR device 14, the EGR gas discharge port B is provided in the intake pipe 4 a between the compressor 25 and the differential pressure device 50, so that the steam atmosphere in the exhaust gas from the gap of the EGR valve 17 at the time of engine key-off Causes the differential pressure device 50 to be exposed to condensation. Due to this condensation, icing occurs in the movable parts of the butterfly valve 52 and the rotating shaft 54 in an area where the outside air temperature is low. Therefore, when the differential pressure device 50 is disposed above the intake system components or above the transmission 62, icing is eliminated at the movable portion of the butterfly valve 52 and the pivot shaft 54 even after warm-up of the engine is completed in areas where the outside air temperature is low. I will not. The operation of the low pressure EGR device 14 cannot be started for a while until icing is eliminated at the movable parts of the butterfly valve 52 and the rotating shaft 54. On the other hand, if the differential pressure device 50 is provided in the vicinity of the exhaust system component, the differential pressure device 50 is exposed to an excessively high temperature atmosphere when the engine is under high load. Therefore, when the engine is cold started, it is necessary to warm up the differential pressure device 50 early to eliminate icing in the movable parts of the butterfly valve 52 and the rotating shaft 54. For this reason, if the hot water piping system is employed for preventing the differential pressure device from freezing, the cost increases. In addition, when the engine load is high, it is necessary to reduce the influence of the radiant heat of the exhaust.

  On the other hand, by providing the EGR cooler 16 in the space in the vertical direction between the exhaust system parts (11a, 11b, 12) and the differential pressure device 50, exhaust flows into the EGR cooler 16 and the exhaust system parts when the engine is cold started. Therefore, the temperatures of the EGR cooler 16 and the exhaust system components rise. When the temperatures of the EGR cooler 16 and the exhaust system components rise, radiant heat of the exhaust gas is emitted to the four sides from the EGR cooler 16 and the exhaust system components. In this case, the differential pressure device 50 is quickly warmed up by the radiant heat of the exhaust gas directed upward from the EGR cooler 16 and the exhaust system components. The early warming up of the differential pressure device 50 eliminates the icing on the butterfly valve 52 and the movable portion of the pivot shaft 54.

  On the other hand, when the engine is heavily loaded, the radiant heat of the exhaust from the exhaust system parts becomes large. If the differential pressure device 50 is exposed to this large amount of radiant heat, the performance of the differential pressure device 50 may be affected. For this reason, although it can be considered to provide a heat shielding member between the EGR cooler 16 and the exhaust system components, providing the heat shielding member raises the cost.

  On the other hand, in the present embodiment, the EGR cooler 16 provided in the space in the vertical direction between the exhaust system components (11a, 11b, 12) and the differential pressure device 50 functions as a heat shield at high load. That is, since the EGR cooler 16 is interposed between the differential pressure device 50 and the exhaust system component, the EGR cooler 16 shuts off a large amount of radiant heat from the exhaust system component to the differential pressure device 50. Overheating of the differential pressure device 50 can be avoided by blocking the radiant heat of the exhaust from the exhaust system components by the EGR cooler 16. In this case, if the EGR cooler 16 is a component that raises the temperature according to the amount of heat absorption of exhaust as well as the exhaust system components (11a, 11b, 12), the exhaust from the EGR cooler 16 at high load The differential pressure device 50 can be overheated by radiant heat. However, this is not the case. That is, even if the outside of the EGR cooler 16 becomes high temperature due to the radiant heat of the exhaust when the load is high, the high temperature heat is transmitted to the internal EGR gas, and the EGR gas becomes high temperature. Then, since the cooling water exchanges heat with the EGR gas having a high temperature in the EGR cooler 16, the temperature of the EGR gas having a high temperature is lowered. That is, the cooling water lowers the overall temperature of the EGR cooler 16. The increase in the ambient temperature of the differential pressure device 50 is suppressed by the endothermic action of the circulating cooling water inside the EGR cooler 16. Thus, since the water-cooled EGR cooler 16 functions as a heat shield at high load, overheating of the differential pressure device 50 at high engine load can be avoided. As described above, the differential pressure device 50 is provided almost right above the space between the exhaust system components and the EGR cooler 16 in the above space because the differential pressure device is warmed up early during cold start. This is to achieve both the machine and the overheat avoidance of the differential pressure device under high load.

  Although FIG. 3 shows a case where the entire EGR cooler 16 is formed in an elongated cylindrical shape, the overall shape of the EGR cooler 16 is not limited to this shape. Since the EGR cooler 16 can take various shapes, various shapes of EGR coolers 16 may be provided so as to pass (obstruct) the space between the differential pressure device 50 and the exhaust system components.

  Next, an EGR valve 17 is provided adjacent to the EGR cooler 16. As described above, since the rise in the ambient temperature of the differential pressure device 50 is suppressed by the heat absorption effect of the circulating cooling water inside the EGR cooler 16, the EGR valve 17 is provided adjacent to the EGR cooler 16 as well. Operation is guaranteed.

  When the engine 1 is viewed from the rear of the vehicle, as shown in FIG. 3, the differential pressure device 50 is provided above the upper surface 61d of the engine block, and the manifold catalyst 12 is provided below the rear surface 61a of the vehicle. There is. Therefore, the EGR gas discharge port B is located above the EGR gas extraction port A. In this case, when the horizontally mounted engine 1 is viewed from the vehicle rear side, the EGR cooler 16 is inclined so that the downstream end 16a of the EGR cooler 16 is positioned above the upstream end 16b of the EGR cooler 16. Set up. As shown in FIG. 3, an acute angle, which is an angle formed by a line passing through the center of the cylindrical EGR cooler 16 (shown by a one-dot chain line) and a horizontal line drawn by a cylinder row direction (shown by a one-dot chain line), is a predetermined value α. (0 ° <α <90 °).

  The EGR passage 15 is constituted by an EGR gas inlet pipe 15 a on the upstream side of the EGR cooler 16 and an EGR gas outlet pipe 15 b on the downstream side of the EGR valve 17. As described above, when the EGR passage 15 is distinguished between the upstream side and the downstream side, the EGR gas inlet pipe 15a is formed by bending to connect the downstream end 12a of the manifold catalyst 12 and the upstream end 16b of the EGR cooler 16. On the other hand, the EGR gas outlet pipe 15b is formed by bending so as to connect the downstream end 17a of the EGR valve 17 and the intake pipe 4a downstream of the differential pressure device 50. Thus, when the engine 1 is viewed from the rear side of the vehicle, the reason why the EGR cooler 16 is inclined as shown in FIG. 3 is the length of the EGR gas inlet pipe 15a and the EGR gas outlet pipe 15b. This is to keep it shorter.

  FIG. 4 is a longitudinal sectional view along the flow of the intake air in the differential pressure device 50 and the intake pipe 4a on the downstream side thereof. FIG. 5 is a cross-sectional view orthogonal to the flow of intake air when the butterfly valve 52 of the differential pressure device 50 is viewed from the downstream side of the flow. Here, it is assumed that the rotation shaft 54 of the butterfly valve 52 is disposed in the horizontal direction when viewed in a cross section orthogonal to the flow of intake air as shown in FIG. And when it sees in the cross section along the flow of intake air as shown in FIG. 4, the butterfly valve 52 shall be closed from the full open position to predetermined opening degree (partial opening degree) (beta).

  Since the EGR gas is hotter than the intake air, when the EGR gas is discharged from the EGR gas discharge port B to the intake pipe 4a and does not immediately mix with the intake air in the intake pipe 4a, the intake pipe 4a at the portion in contact with the EGR gas The inner wall is partially exposed to high temperatures. In order to cope with this, if the intake pipe 4a near the EGR gas outlet B is made to be a high-temperature compatible material, the cost is increased because the high-temperature compatible material is expensive.

  Therefore, in the present embodiment, in order to diffuse (disperse) the EGR gas discharged from the EGR gas discharge port B early in the space of the intake pipe 4a, the separation vortex generated downstream of the butterfly valve 52 with the partial opening β is used. Do. This will be described. By closing the butterfly valve 52 to the partial opening degree β shown in FIG. 4, the intake air flows upstream through the gap between the outer periphery 52 a of the butterfly valve 52 and the inner periphery 51 a of the cylindrical main body 51 (see FIG. 4 from the left side to the downstream side (right side in FIG. 4). At this time, a large number of separation vortices V are generated in the intake air passing through the space between the outer periphery 52a of the butterfly valve 52 and the main body inner periphery 51a in the clearance region R1 near the pivot shaft 54. Moves downstream toward the flow of intake air while preserving the state of the vortex. The separation vortex V is generated in the gap between the outer periphery 52a of the butterfly valve 52 and the inner periphery 51a of the main body and does not disappear immediately, but is stored in a vortex state and is on the downstream side with the flow of intake air. It disappears after flowing through the distance. On the other hand, the separation vortex V no longer occurs in the suction air passing through the gap between the outer periphery 52a of the butterfly valve 52 and the inner periphery 51a of the butterfly valve 52 in the gap region R2 that is separated from the rotation shaft 54 to some extent, and rectification without vortex is performed. Inhalation air moves in the state of the contact (see the long arrow in FIG. 4). Hereinafter, when the butterfly valve 52 is viewed from the downstream side of the flow, as shown in FIG. 5, the suction passing through the gap between the outer periphery 52a of the butterfly valve 52 and the inner periphery 51a of the main body about the rotation shaft 54. The clearance area R1 in which the separation vortex is generated in the air is referred to as "a separation vortex main generation area". A gap region R2 in which no separation vortex is generated in the intake air passing through the gap between the outer periphery 52a of the butterfly valve 52 and the inner periphery 51a of the main body is referred to as a “main flow region”.

  Downstream of the butterfly valve 52 with the partial opening degree β, the main flow region R2 and the separation vortex main generation region R1 are distributed and generated in the circumferential direction of the cylindrical main body 51. In this case, when viewed from the downstream side of the flow, as shown in FIG. 5, the main flow region R2 and the separation vortex main generation region R1 occur in symmetrical positions in the left-right direction. Specifically, as shown in FIG. 5, in the right half region, a range of a predetermined angle γ / 2 above and below the rotation axis 54 located in the horizontal direction is a separation vortex main generation region R1, The range that remains above and below is the right half of the mainstream region R2. Similarly, in the left half area, a range with a predetermined angle γ / 2 at each of the upper and lower sides with respect to the rotation axis 54 positioned in the horizontal direction is the main peeling vortex generation area R1 and the remaining area at the upper and lower areas is the main flow area R2. The left half.

  In this case, the range of the two regions R1 and R2 does not necessarily coincide with the angles γ and δ, respectively, when viewed in a cross section separated by a predetermined distance from the rotation shaft 54 to the downstream side. However, it is considered that the range of the two regions R1 and R2 generated in the vicinity of the rotation shaft 54 is stored as it is in the range of the predetermined length L0 from the rotation shaft 54 on the downstream side in the flow direction it can. That is, the boundaries R1 and R2 between the two regions are stored as they are within a predetermined length L0 from the rotation shaft 54.

  As described above, when the cross section perpendicular to the flow and the cross section along the flow are distinguished into the two regions R1 and R2, a predetermined length from the rotation shaft 54 near the boundary between the main flow region R2 and the separation vortex main generation region R1. An EGR gas discharge port B is provided in the intake pipe 4a on the downstream side away from L1. That is, when the butterfly valve 52 is viewed from the downstream side of the flow as shown in FIG. 5, the EGR gas discharge is directed in the direction inclined at a predetermined angle (= γ / 2) which is an acute angle in the circumferential direction from the cross section center C of the flow. An outlet B is provided. This is because by utilizing the separation vortex V for stirring the EGR gas and the intake air discharged from the EGR gas discharge port B, it is possible to rapidly mix the EGR gas and the intake air. As a result, it is possible to avoid making the intake pipe 4a an expensive high temperature compatible material.

  The reason for providing the EGR gas discharge port B in the intake pipe 4a on the downstream side away from the rotating shaft 54 by the predetermined length L1 is as follows. That is, when the EGR gas discharge port B is immediately downstream of the butterfly valve 52, the EGR gas may flow backward toward the upstream side when the engine is stopped. At this time, it is conceivable that components in the EGR gas adhere to the butterfly valve 52 and contaminate the butterfly valve 52. Therefore, when viewed in a cross section along the flow of intake air, the range of the two regions R1 and R2 is as shown in FIG. 4 in the range of the intake pipe 4a stored as it is downstream of the rotary shaft 54. The EGR gas discharge port B is provided in the intake pipe 4a on the downstream side that is a predetermined length L1 away from the moving shaft 54. Here, the predetermined length L1 is equal to or less than the predetermined length L0 from the rotation shaft 54 in which the boundaries R1 and R2 of the two regions are stored as they are on the downstream side.

  As a result, even if the EGR gas reversely flows from the EGR gas discharge port B toward the upstream side when the engine is stopped, the backflowing EGR gas stops flowing while flowing through the predetermined distance L1, and the butterfly valve 52 Never reach. It is possible to prevent the differential pressure device 50 from becoming dirty when the engine is stopped. As described above, by providing the EGR gas discharge port B in the intake pipe 4a separated by the predetermined distance L1 downstream of the butterfly valve 52, the overheating of the intake pipe 4a by the EGR gas can be avoided and the differential pressure device at engine stop 50 dirt can be prevented.

  Here, if the separation vortex V is not used, the intake pipe length from the rotary shaft 54 until the EGR gas discharged from the EGR gas discharge port B finishes diffusing into the intake air is the predetermined length L1. Will be longer. In other words, by using the separation vortex V generated in the differential pressure device 50 with the partial opening β for stirring the EGR gas discharged from the EGR gas discharge port B, the differential pressure device is compared with the case where the separation vortex V is not used. The intake pipe distance from 50 to the EGR gas discharge port B can be shortened.

  In FIG. 5, the EGR gas outlet B is provided at the upper right boundary of the two regions R1 and R2, but the present invention is not limited to this position. As shown in FIG. 5, the boundary between the two regions R1 and R2 has four positions of upper right, lower right, upper left, and lower left, so that the four positions of the EGR gas outlet pipe 15b are not increased. Either of these may be adopted.

  The position of the boundary between the two regions R1 and R2 in the cross section perpendicular to the flow and the cross section along the flow corresponds to the flow velocity of the intake air or the partial angle β of the butterfly valve 52 if the diameter of the main body 51 is determined. Depending on it can be different. Therefore, finally, the position of the EGR gas outlet B and the predetermined length L1 are determined by adaptation.

  Here, the operation and effect of the present embodiment will be described including problems and requirements.

The differential pressure device 50 provided in the intake pipe 4 a on the upstream side of the EGR gas discharge port B has the following two problems 1 and 2. That is,
Problem 1: Warm up differential pressure device 50 early at cold start of the engine (cancel freezing),
Problem 2: avoiding overheating of the differential pressure device 50 when the engine is heavily loaded,
Two.

The requirements 1 and 2 for the tasks 1 and 2 are as follows. That is,
Requirement 1: To make the differential pressure device 50 close to the exhaust system parts (11a, 11b, 12) so that the differential pressure device 50 is easily subjected to radiant heat of the exhaust during warm-up.
Requirement 2: To reduce the influence of exhaust heat from the exhaust system parts (11a, 11b, 12) to the differential pressure device 50 when the engine is heavily loaded.
It is said that.

  In order to meet the above two requirements 1 and 2, in this embodiment, as a premise, an intake system component, an exhaust system component, a turbocharger 21, a low pressure EGR device 14 (EGR device), and a differential pressure device 50. The intake system parts include an intake pipe 4a through which intake air introduced into an engine block 61 having a cylinder row flows, an intake manifold 4c connected to the intake pipe 4a and distributing intake air, and an air cleaner 47 provided at an upstream end of the intake pipe 4a. Configured The exhaust system component is composed of an exhaust pipe 11 b through which gas exhausted from the engine block 61 flows. The turbocharger 21 includes a turbine 22 provided in the exhaust pipe 11b and a compressor 25 provided in the intake pipe 4a. The low-pressure EGR device 15 includes an EGR passage 15, an EGR valve 17, and a water-cooled EGR cooler 16. The EGR passage 15 communicates the exhaust pipe 11b downstream of the turbine 22 and the intake pipe 4a upstream of the compressor 25. The EGR valve 17 opens and closes the EGR passage 15. The water-cooled EGR cooler 16 cools the EGR gas upstream of the EGR valve 17. The differential pressure device 50 is provided in the intake pipe 4a upstream of the EGR gas discharge port (EGR gas discharge port). In this embodiment, when the engine block 61 is viewed from above, the intake manifold 4c is on the front side of the vehicle centering on the cylinder row of the engine block 61, and the exhaust system component (11b) and the turbocharger 21 on the rear side of the vehicle. Is placed. Further, in the present embodiment, the differential pressure device 50 is provided on the upper side with a predetermined space between the exhaust system parts, so as to pass through the space between the exhaust system parts (11 b) and the differential pressure device 50. An EGR cooler 16 is provided. Since the water-cooled EGR cooler 16 functions as an exhaust system component at the time of cold start of the engine, the radiation heat of the exhaust gas from the EGR cooler 16 can warm up the differential pressure device 50 at an early stage. Since icing on the butterfly valve 52 of the actuating device 50 and movable parts of the pivot shaft 54 is eliminated before engine warm-up is completed during cold start of the engine, low-pressure EGR is performed immediately after engine warm-up is completed. The device 14 can be activated. Compared with the case where the low pressure EGR device 14 cannot be operated immediately after the engine warm-up is completed due to icing in the movable parts of the butterfly valve 52 and the rotating shaft 54, fuel consumption can be improved. . In addition, since the differential pressure device 50 can be warmed up promptly by changing the layout of parts, the hot water piping system for preventing differential pressure device freezing can be eliminated. Further, since the traveling air does not easily hit the differential pressure device 50 because of the front intake / rear exhaust layout, the icing at the movable portion of the butterfly valve 52 and the pivot shaft 54 can be eliminated more quickly.

  On the other hand, at the time of high engine load, the radiant heat of the exhaust from the exhaust system part (11b) becomes larger than immediately after the cold start of the engine. For this reason, if the radiant heat of the exhaust from the exhaust system component directly strikes the differential pressure device 50, the differential pressure device 50 is exposed to high temperature. In this case, since the water-cooled EGR cooler 16 is interposed between the differential pressure device 50 and the exhaust system components, the EGR cooler 16 blocks the radiation heat from the exhaust system components to the differential pressure device 50. The radiant heat of the exhaust gas from the exhaust system components colliding with the EGR cooler 16 does not reach the differential pressure device 50. Thus, overheating of the differential pressure device 50 can be avoided by blocking the radiant heat of the exhaust from the exhaust system components by the EGR cooler 16. In addition, the temperature of the entire EGR cooler 16 is maintained at a temperature lower than that of the exhaust system components by the heat absorbing action of the circulating cooling water inside the EGR cooler 16. As a result, an increase in the ambient temperature of the differential pressure device 50 is suppressed, so that the influence of exhaust radiant heat can be mitigated when the engine is heavily loaded. Further, the heat shield member can be simplified. As described above, in the present embodiment, it is possible to achieve both early warming up of the differential pressure device 50 at the time of engine cold start and overheat avoidance of the differential pressure device 50 at the time of high engine load.

  Note that the maximum effect is obtained when the EGR cooler 16 passes through (shuts off) the entire space between the differential pressure device 50 and the exhaust system components, but between the differential pressure device 50 and the exhaust system components It is sufficient to pass through at least a part of the space.

In the present embodiment, the differential pressure device 50 is disposed at the upper part of the engine block 61 and on the exhaust system component side.
By this, as the differential pressure device 50 approaches exhaust system parts, it becomes easy to receive the radiant heat of the exhaust gas from the EGR cooler 16 and the exhaust system parts, and early warm-up of the differential pressure device 50 can be further promoted.

  In the present embodiment, the EGR gas outlet B is disposed above the EGR gas outlet A, and the downstream end 16a of the EGR cooler 16 is positioned above the upstream end 16b of the EGR cooler 16. The EGR cooler 16 is provided to be inclined. Thereby, the tube length of the EGR gas inlet pipe 15a and the EGR gas outlet pipe 15b can be suppressed to be shorter than the case where the EGR cooler 16 is provided in parallel.

Further, under the above-described problems 1 and 2, there are the following two sub-tasks 1 and 2. That is,
Sub-task 1: Avoiding a decrease in the efficiency of the compressor 25 due to the EGR gas discharged from the EGR gas discharge port B flowing into the compressor 25 without being diffused.
Sub-task 2: Avoiding the contamination of the differential pressure device 50 due to the EGR gas blowing back when the engine is stopped,
Two.

The requirements 3 and 4 for the sub-tasks 1 and 2 are as follows. That is,
Demand 3: To ensure the intake pipe distance from the EGR gas outlet B to the compressor 25 so that the EGR gas discharged from the EGR gas outlet B sufficiently diffuses into the intake air and then flows into the compressor 25.
Requirement 4: In order to prevent the differential pressure device 50 from becoming dirty due to the backflow of EGR gas when the engine is stopped, it is necessary to secure the intake pipe distance between the differential pressure device 50 and the EGR gas discharge port B.
It is said that.

  In order to meet the above two requirements 3 and 4, in the present embodiment, the air cleaner 47 and the compressor 25 are disposed on the opposite side of the engine block 61 in the cylinder row direction. That is, the compressor upstream intake pipe 4a is bent after rising upward from the inlet of the compressor 25, and is bent above the upper surface 61d of the engine block 61. The exhaust system component side is directed horizontally and toward the engine rear side. Provide to extend. An air cleaner 47 is provided at the upstream end of the compressor upstream side intake pipe 4a. As a result, the length of the compressor upstream side intake pipe 4a in the cylinder row direction becomes long. The intake pipe distance between the EGR gas discharge port B and the compressor 25 and the distance between the differential pressure device 50 and the EGR gas discharge port B are as much as the length of the compressor upstream side intake pipe 4a in the cylinder row direction can be increased. The intake pipe distance can be secured longer.

Further, under the sub-tasks 1 and 2, there are the following sub-tasks 3 and 4. That is,
Sub-task 3: Avoiding overheating of the intake pipe 4a downstream of the EGR gas outlet B by diffusing the EGR gas discharged from the EGR gas outlet B into the intake air at an early stage.
Sub-task 4: Preventing the differential pressure device 50 from being polluted by the blowback of EGR gas when the engine is stopped,
It is.

The requirements 5 and 6 for the sub-problems 3 and 4 are as follows. That is,
Requirement 5: In order to use the separation vortex generated in the butterfly valve 52 of the differential pressure device with the partial opening β to stir the EGR gas discharged from the EGR gas discharge port B, the differential pressure device 50 to the EGR gas discharge port B Want to reduce the distance between the intake pipes,
Requirement 6: In order to prevent the differential pressure device 50 from becoming dirty due to the blow-back of EGR gas when the engine is stopped, it is necessary to secure the intake pipe distance from the differential pressure device 50 to the EGR gas discharge port B.
It is said that.

  The reason why the peeling vortex V is used in the above requirement 5 is as follows. That is, in order to avoid overheating of the intake pipe downstream of the EGR gas discharge port B, the EGR gas discharge port B needs to be rapidly stirred with the intake air. This is because it is effective to use the stirring effect by the separation vortex generated in the butterfly valve 52 of the differential pressure device with the partial opening degree β in order to make stirring rapidly.

  In order to meet the above two requirements 5 and 6, in the present embodiment, the boundary between the main flow region R2 and the separation vortex main generation region R1 generated circumferentially distributed downstream of the butterfly valve 52 of the differential pressure device with a partial opening degree β. An EGR gas discharge port is provided in the nearby intake pipe 4a. That is, when the butterfly valve 52 is viewed from the downstream side of the flow, the EGR gas discharge port B is provided in a direction inclined by a predetermined angle (γ / 2) in the circumferential direction from the cross section center C of the flow. This is because downstream of the butterfly valve 52 with the partial opening β, the main flow region R2 and the separation vortex main generation region R1 are distributed in the circumferential direction of the cylindrical main body 51 and the downstream intake pipe 4a. This is because the vicinity of the boundary of R2 is a position where the stirring effect by the separation vortex V can be obtained to the most downstream side. As a result, the EGR gas and the intake air can be quickly mixed by utilizing the stirring effect of the separation vortex V at a position distant to the downstream side of the differential pressure device 50. Therefore, the intake pipe 4a downstream of the EGR gas discharge port B can be designed without using an expensive high temperature compatible material. Thus, while securing the intake pipe distance from the differential pressure device 50 to the EGR gas discharge port B, the EGR at a position where the separation vortex generated by the differential pressure device 50 easily reaches the downstream and reaches the flow The gas is discharged, and the separation vortex can be effectively used for stirring.

  In the embodiment, the case where the EGR cooler 16 is a water-cooled type that cools the EGR gas with cooling water has been described. However, the present invention is not limited to this, and any liquid-cooled type that cools the EGR gas with a coolant may be used. .

  In the embodiment, the horizontal engine 1 has been described as being substantially upright. The invention is not limited in this case. For example, the transversely mounted engine 1 may be mounted at a predetermined angle on the vehicle front side or the vehicle rear side, or on the engine front side or the engine rear side. In this case, the present invention can be applied.

  In the embodiment, the water-cooling type EGR cooler 16 which performs heat exchange between the EGR gas and the cooling water is mentioned as the EGR gas cooling device, but the EGR gas cooling device is a liquid cooling type cooling device such as a water cooling type. It is not limited to the case. This is because the EGR gas can be cooled even when the refrigerant performing heat exchange with the EGR gas flows in a non-liquid gaseous state.

1 Horizontal engine 4a Intake pipe 4c Intake manifold 11a Exhaust manifold 11b Exhaust pipe 12 Manifold catalyst 14 Low pressure EGR device (EGR device)
15 EGR passage 16 Water-cooled EGR cooler (EGR gas cooling device)
17 EGR valve 21 Turbocharger 22 Turbine 25 Compressor 47 Air cleaner 50 Differential pressure device 52 Butterfly valve 61 Engine block A EGR gas outlet B EGR gas outlet

Claims (5)

An intake system component including an intake pipe through which intake air introduced into an engine block having a cylinder row flows, an intake manifold connected to the intake pipe for distributing the intake air, and an air cleaner provided at an upstream end of the intake pipe;
An exhaust system component composed of an exhaust pipe through which gas exhausted from the engine block flows;
A turbo charger comprising a turbine provided in the exhaust pipe, and a compressor provided in the intake pipe;
EGR gas is a passage through which an exhaust pipe downstream of the turbine communicates with an intake pipe upstream of the compressor, an EGR valve that opens and closes the EGR passage, and an EGR gas that cools the EGR gas upstream of the EGR valve An EGR device having a gas cooling device;
A differential pressure device provided in an intake pipe upstream from the discharge port of the EGR gas;
Equipped with
When the engine block is viewed from above, the intake manifold is placed on one side in the direction perpendicular to the cylinder row direction, with the cylinder row of the engine block as the center, and on the other side in the direction perpendicular to the cylinder row direction. Arranging the exhaust system parts and the turbocharger;
A vertical space is provided between the exhaust system parts and the differential pressure device is provided at a position where the exhaust system parts and the differential pressure device overlap when viewed from above .
An engine comprising the EGR gas cooling device that passes through the space and is interposed between the differential pressure device and the exhaust system component.   The engine according to claim 1, wherein the differential pressure device is disposed above the upper surface of the engine block and on the exhaust system component side.   The EGR gas discharge port is disposed above the EGR gas outlet, and the downstream end of the EGR gas cooling device is positioned above the upstream end of the EGR gas cooling device. The engine according to claim 1 or 2, wherein the EGR gas cooling device is provided at an incline.   The engine according to any one of claims 1 to 3, wherein the air cleaner and the compressor are disposed on the opposite side of the cylinder block direction of the engine block. The discharge port for the EGR gas is provided in an intake pipe in the vicinity of a boundary between a main flow region generated in a circumferential direction downstream of the differential pressure device having a partial opening and a separation vortex main generation region. The engine according to any one of 4 to 4.

Images