JP7521366B2 - Internal combustion engine - Google Patents

Description

This disclosure relates to an internal combustion engine having an exhaust gas recirculation system.

Internal combustion engines are known that have an exhaust gas recirculation device that recirculates a portion of the exhaust gas discharged from the internal combustion engine to the intake air as exhaust gas recirculation gas (see, for example, Patent Document 1). In the internal combustion engine of Patent Document 1, a portion of the exhaust gas discharged from the cylinder and passed through the exhaust purification device is introduced into the intake air.

The internal combustion engine of Patent Document 1 is provided with a cooling device for cooling the recirculated exhaust gas. In the exhaust purification device of Patent Document 1, the cooling device is cooled by a coolant, and the exhaust recirculated gas is introduced into the intake air at a reduced temperature. In the exhaust purification device of Patent Document 1, the cooling device is arranged below the exhaust manifold, allowing the exhaust purification device to be arranged compactly.

International Publication No. 2012/056885

However, in the internal combustion engine of Patent Document 1, the cooling device is placed in a space surrounded by the cylinder block and the exhaust purification device from the front to the rear, and surrounded by the exhaust manifold from above. This type of space makes it difficult for the wind flowing toward the internal combustion engine to escape. For this reason, heat released from the exhaust manifold and the exhaust purification device tends to be trapped in the space. This makes it easy for the coolant flowing through the cooling device to heat up. When the coolant is heated, the temperature of the exhaust recirculation gas increases, and the intake air temperature tends to rise.

The objective of this disclosure is to provide an internal combustion engine that can prevent excessive heating of the cooling device.

The internal combustion engine according to the present disclosure is an internal combustion engine mounted on a vehicle, and includes a cylinder block, an intake passage, a supercharger, an exhaust purification device, an exhaust recirculation passage, an exhaust recirculation valve, and a cooling device. The cylinder block has cylinders formed therein and holds a crankshaft. The intake passage supplies intake air to the cylinders. The supercharger supercharges the intake air flowing through the intake passage. The exhaust purification device is disposed displaced in the extension direction of the crankshaft relative to the supercharger, and extends in the extension direction of the cylinders. The exhaust recirculation passage is connected to the intake passage from downstream of the exhaust purification device. The exhaust recirculation valve is disposed on the exhaust recirculation passage, displaced in the extension direction of the crankshaft relative to the exhaust purification device. The cooling device is disposed on the exhaust recirculation passage, and cools exhaust recirculation gas flowing through the exhaust recirculation passage with a coolant. The exhaust recirculation valve, the cooling device, and the exhaust purification device are disposed in this order along the extension direction of the crankshaft. One side of the cooling device is disposed between the exhaust purification device and the cylinder block, and the other side is disposed in a space surrounded by the turbocharger, the exhaust purification device, and the exhaust recirculation valve, with the lower side of the turbocharger being between the exhaust recirculation valve and the exhaust purification device .

With this internal combustion engine, one side of the cooling device is disposed between the cylinder block and the exhaust purification device, so the coolant can be easily heated. This makes it easier to raise the temperature of the cold coolant during a cold start of the internal combustion engine, for example. As a result, it is easier to promote warming up of the internal combustion engine. Meanwhile, the other side of the cooling device is disposed in the space between the turbocharger and the exhaust recirculation valve and the exhaust purification device, so heat escapes from this space. This makes it possible to prevent excessive heating of the cooling device, for example, when the temperature of the internal combustion engine is high.

The vehicle 's driveline may be located below the cooling system.

With this configuration, debris flying from underneath the vehicle is directed toward the power transmission device, which has a relatively robust structure, preventing damage to the cooling device.

The cooling device may be arranged at an angle so that it approaches the cylinder block as it approaches the exhaust purification device.

This configuration allows the cooling device to be arranged compactly. Furthermore, by arranging it in this way, the cooling device is arranged alongside the exhaust purification device, making it easier to raise the temperature of the chilled coolant, for example, during a cold start of the internal combustion engine.

The internal combustion engine may further include a coolant supply passage that supplies coolant to the cooling device. The coolant supply passage may pass between the exhaust purification device and the cooling device.

This configuration makes it easier to increase the temperature of the coolant flowing through the coolant supply passage. This makes it easier to increase the temperature of the cold coolant, for example, during a cold start of an internal combustion engine.

The exhaust recirculation passage may be arranged to slope downward as it approaches the exhaust purification device from the intake passage.

This configuration helps prevent condensed water from flowing into the intake passage.

The vehicle may have a heater device for heating the interior of the vehicle. The coolant may flow through the cooling device and then to the heater device.

This configuration improves the vehicle's heater performance.

This disclosure provides an internal combustion engine that can prevent excessive heating of the cooling device.

1 is a conceptual diagram of an internal combustion engine according to an embodiment of the present disclosure mounted on a vehicle; 1 is a rear view of an internal combustion engine according to an embodiment of the present disclosure. IV-IV cross-sectional view of FIG. 2 is a cross-sectional view taken along the line VV in FIG. FIG. 1 illustrates an inlet fitting according to an embodiment of the present disclosure. 1 is a cross-sectional view of an inlet fitting according to an embodiment of the present disclosure, taken near the center of a through hole.

One embodiment of the present disclosure will be described below with reference to the drawings. In the following specification, the longitudinal direction of the vehicle is indicated as Q in the drawings, and the front is indicated as F. The width direction of the vehicle is indicated as P in the drawings, and the right side as viewed from the rear of the vehicle is indicated as R. Furthermore, the vertical direction of the vehicle is indicated as G in the drawings, and the upper side is indicated as U.

As shown in Figures 1 and 2, the internal combustion engine 1 includes a cylinder block 2, a cylinder head 4, an intake passage 6, a turbocharger 8, an exhaust purification device 10, an exhaust gas recirculation passage 12, an exhaust gas recirculation valve 14, a cooling device 16, a coolant supply passage 18, and a coolant discharge passage 20.

In this embodiment, the internal combustion engine 1 is an in-line four-cylinder type internal combustion engine in which four cylinders 2a are formed in-line in the cylinder block 2. The internal combustion engine 1 has a crankshaft 2b extending in the direction in which the cylinders 2a are arranged. The crankshaft 2b is held by the cylinder block 2. However, the type and arrangement direction of the internal combustion engine 1 are not limited to an in-line type, and may be, for example, a horizontally opposed type or a V-type.

The internal combustion engine 1 is mounted on a vehicle C. The vehicle C has a transmission 21, a differential gear box (an example of a power transmission device) 22, and a heater device 24. The transmission 21 changes the speed of the power of the internal combustion engine 1 and transmits it to the differential gear box 22. The differential gear box 22 reduces the speed of the power transmitted from the transmission 21 and drives the wheels W via a drive shaft 26. The heater device 24 is a device that uses the heat of the coolant flowing through the internal combustion engine 1 to heat the interior of the vehicle C. In this embodiment, the heater device 24 is disposed behind the dash panel (not shown) of the vehicle C.

When the internal combustion engine 1 is started in a cold state, the coolant absorbs heat by passing through the internal combustion engine 1 and the cooling device 16. The absorbed heat warms up, warming up the internal combustion engine 1, and also warms the interior of the vehicle by passing through the heater device 24.

After the internal combustion engine 1 is warmed up, a thermostat (not shown) opens and coolant is supplied to a radiator (not shown) to cool the coolant. The coolant that passes through the radiator cools the internal combustion engine 1 and is also supplied to the cooling device 16 to cool the exhaust gas recirculation gas described below.

In this embodiment, the internal combustion engine 1 is disposed with the extension direction of the crankshaft 2b (hereinafter referred to as the crankshaft extension direction in the specification) of the vehicle C aligned with the vehicle width direction P of the vehicle C. The transmission 21 is disposed on the left side of the internal combustion engine 1. The differential gear box 22 is formed with a relatively robust structure using aluminum die casting or the like, and is disposed on the right side R of the transmission 21. In other words, the vehicle C of this embodiment is a front-wheel drive type with the internal combustion engine 1 disposed transversely.

The cylinder head 4 is disposed on top of the cylinder block 2. The cylinder head 4 is formed with an intake port that supplies intake air to the cylinders 2a, and the intake port is connected to the intake passage 6 via an intake manifold (not shown), an intercooler (not shown), and a turbocharger 8. In this embodiment, an exhaust collection section 4a that collects exhaust gas discharged from the four cylinders 2a is formed integrally inside the cylinder head 4 (see FIG. 3).

The intake passage 6 has a curved portion 6h. The curved portion 6h is formed into a curved shape by the inlet fitting 6a. The inlet fitting 6a is formed into a cylindrical shape using a metal member such as aluminum, and the intake passage 6 is formed inside. In this embodiment, the inlet fitting 6a is formed into a curved shape from the upper U of the vehicle C toward the right side R in the vehicle width direction P. Due to this shape, the inlet fitting 6a smoothly connects the intake passage 6, which extends from the front F side of the vehicle toward the rear and turns downward behind the internal combustion engine 1, to the inlet of the compressor 8b, which will be described later. In addition, the inlet fitting 6a has a through hole 6c that penetrates the wall surface of the intake passage 6, and functions as an introduction portion that introduces the exhaust recirculation gas that has passed through the inside of the nipple 6b into the intake passage 6.

In such an inlet fitting 6a, the pressure of the intake air flowing outside the curved portion 6h is high, and the pressure of the intake air flowing inside the curved portion 6h is low. In addition, due to the rotation of the compressor 8b described below, a swirling flow along the rotation direction of the compressor 8b is likely to occur in the intake passage 6 formed in the inlet fitting 6a. More specifically, the intake air flowing through the intake passage 6 upstream of the compressor 8b is dragged in the rotation direction of the compressor 8b, generating a swirling flow along the rotation direction of the compressor 8b. For this reason, the condensed water that flows into the intake passage 6 is centrifuged by the swirling flow and is likely to scatter toward the inner circumference X of the intake passage 6.

The turbocharger 8 has a turbine 8a and a compressor 8b arranged coaxially with the turbine 8a. As shown in FIG. 3, the turbine 8a is fixed to the outlet flange 4b of the exhaust collection section 4a. In this embodiment, the turbine 8a is attached so that the exhaust flows upward from the outlet flange 4b. By arranging the turbine 8a in this way, the turbine 8a is easily cooled by the running wind passing between the internal combustion engine 1 and the hood covering the engine room in which the internal combustion engine 1 is housed.

The compressor 8b is disposed in the intake passage 6 and rotates counterclockwise when viewed from the transmission 21 side (see FIG. 6). The upstream side of the compressor 8b is connected to the intake passage 6 by an inlet fitting 6a that is curved from the upper side U by a curved portion 6h and then extends in the crankshaft extension direction (in this embodiment, the vehicle width direction P). In the supercharger 8, the turbine 8a rotates due to the exhaust flowing from the exhaust collection portion 4a, which rotates the compressor 8b, supercharging the intake air flowing through the intake passage 6.

As shown in FIG. 2, the exhaust purification device 10 is disposed displaced forward in the crankshaft extension direction (to the right in the vehicle width direction P in this embodiment) relative to the turbocharger 8. Note that the crankshaft 2b is generally referred to as the rear side on the transmission 21 side and the opposite side as the front side. Therefore, in this embodiment, the front side as viewed in the crankshaft extension direction corresponds to the right side in the vehicle width direction P, and the rear side as viewed in the crankshaft extension direction corresponds to the left side in the vehicle width direction P.

The exhaust purification device 10 is disposed downstream of the turbine 8a and purifies the exhaust gas. In this embodiment, the exhaust purification device 10 includes a catalyst section 10a, an inlet pipe 10b, and an outlet pipe 10c. The catalyst section 10a is formed by inserting a honeycomb carrier coated with a three-way catalyst that purifies carbon monoxide and other gases discharged from the cylinder 2a into a metal tubular member. When the internal combustion engine 1 is started in a cold state, the catalyst section 10a is controlled to be at a high temperature.

In the exhaust purification device 10, the catalyst section 10a extends in the extension direction of the cylinder 2a (hereinafter referred to as the cylinder extension direction in the specification). In this embodiment, the cylinder extension direction of the cylinder block 2 is arranged along the vertical direction G of the vehicle C. Therefore, in this embodiment, the cylinder extension direction is approximately the same as the vertical direction G. The cylinder block 2 may be arranged with the upper part of the cylinder 2a slightly tilted toward the rear of the vehicle C (see FIG. 3). That is, in this embodiment, the exhaust purification device 10 has the inlet pipe 10b arranged on the right side R (front side as viewed in the crankshaft extension direction) of the turbine 8a in the vehicle width direction P. The inlet pipe 10b is curved downward and connected to the catalyst section 10a. The catalyst section 10a is offset to the right side from the turbine 8a by the inlet pipe 10b. The outlet pipe 10c is connected to the lower part of the catalyst section 10a, curves toward the left, and then extends toward the rear of the vehicle. A heat protector made of a plate-shaped metal member that matches the shape of the exhaust purification device 10 may be provided around the exhaust purification device 10.

The internal combustion engine 1 is provided with an exhaust gas recirculation passage 12, an exhaust gas recirculation valve 14, and a cooling device 16, thereby constituting an exhaust gas recirculation system. The exhaust gas recirculation system is provided to re-burn the exhaust gas by circulating a part of the exhaust gas discharged from the cylinder 2a to the intake air as exhaust gas recirculation gas. The internal combustion engine 1 improves the fuel efficiency of the vehicle C while reducing nitrogen oxides by re-burning the exhaust gas. In this embodiment, the exhaust gas recirculation system is a low-pressure exhaust gas recirculation system in which the exhaust gas recirculation passage 12 is connected from downstream of the exhaust gas purification device 10 to upstream of the compressor 8b of the intake passage 6. However, the exhaust gas recirculation system is not limited to this, and may be a high-pressure exhaust gas recirculation system in which the exhaust gas recirculation passage 12 is connected downstream of the compressor 8b. Note that exhaust gas recirculation may also be abbreviated as EGR (Exhaust Gas Recirculation).

The exhaust recirculation passage 12 extends downward from the intake passage 6 and bends to the right R toward the exhaust purification device 10. The exhaust recirculation passage 12 passes between the exhaust purification device 10 and the cylinder block 2 and is connected to the outlet pipe 10c of the exhaust purification device 10 (see FIG. 4). The exhaust recirculation passage 12 slopes downward as it moves from the intake passage 6 toward the outlet pipe 10c toward the exhaust purification device 10. That is, the exhaust recirculation passage 12 slopes downward as it moves toward the right R. This allows condensed water generated by the exhaust recirculation gas being cooled by the cooling device 16 to flow downward due to its own weight, preventing the condensed water from flowing into the intake passage 6.

In this embodiment, the exhaust recirculation passage 12 is connected to the intake passage 6 by a nipple 6b with a circular cross section that is provided downward from the inlet fitting 6a, as shown in FIG. 5. Also, as shown in FIG. 2, the exhaust recirculation passage 12 is composed of a first passage 12a from the nipple 6b to the exhaust recirculation valve 14, a second passage 12b from the exhaust recirculation valve 14 to the cooling device 16, a third passage 12c that passes through the cooling device, and a fourth passage 12d from the cooling device 16 to the outlet pipe 10c. The first passage 12a, the second passage 12b, the third passage 12c, and the fourth passage 12d are each a pipe with a circular cross section.

The first passage 12a is formed by a rubber hose and a metal nipple attached to the exhaust recirculation valve 14. The second passage 12b is formed by a metal member such as aluminum. The third passage 12c is formed by a stainless steel passage from the inlet flange 16c of the cooling device 16 to the outlet side 16b of the cooling device 16 described later, and the cooling device 16 is provided around this stainless steel passage. The fourth passage 12d is formed by a stainless steel pipe. The exhaust recirculation gas enters the fourth passage 12d from the outlet pipe 10c of the exhaust purification device 10, passes through the third passage 12c, the second passage 12b, the first passage 12a, and the nipple 6b in this order, and flows into the intake passage 6.

As shown in FIG. 6, the exhaust circulation passage 12 extends downward from the through hole 6c in the direction of the tangent TL of the inner circumference X of the intake passage 6. The exhaust circulation passage 12 is offset (displaced) relative to the intake passage 6 in a direction perpendicular to the extension direction of the intake passage 6 (in this embodiment, in either the vertical direction G or the front-rear direction Q, or in a diagonal direction between the vertical direction G and the front-rear direction Q). In this way, the exhaust circulation passage 12 extends along the tangent TL direction and is offset in a direction perpendicular to the extension direction of the intake passage 6, so that condensed water centrifuged by the swirling flow generated in the intake passage 6 is easily pushed back into the exhaust circulation passage 12.

As shown in FIG. 5, the exhaust circulation passage 12 extends toward the outside of the curved portion 6h. More specifically, at least a portion of the through hole 6c is disposed near the lower end of the curved portion 6h (see FIG. 2). The exhaust circulation passage 12 extends downward from the through hole 6c and toward the radial outside (lower in this embodiment) of the portion where the curved portion 6h curves from above toward the right side R. In this way, the exhaust circulation passage 12 extends toward the outside of the curved portion 6h, so that the condensed water is easily pushed back to the exhaust circulation passage 12 by the pressure of the intake air flowing outside the intake passage 6 formed in the curved portion 6h. As a result, it is easy to suppress the inflow of condensed water into the intake passage 6. Furthermore, even if the condensed water flows into the intake passage 6, it is easily pushed back from the intake passage 6 to the exhaust circulation passage 12.

The exhaust recirculation passage 12 is connected to the intake passage 6 toward the upstream of the intake passage so as to form an acute angle with the intake passage 6. More specifically, as shown in FIG. 2, the angle α between the intake passage center line (see two-dot chain line Oa), which is a virtual line passing through the approximate center of the intake passage 6, and the exhaust recirculation passage center line (see two-dot chain line Oe), which is a virtual line passing through the approximate center of the exhaust recirculation passage 12, is an acute angle. As a result, the exhaust recirculation passage 12 is connected against the direction in which the intake air of the intake passage 6 flows, and the exhaust recirculation gas flowing through the exhaust recirculation passage 12 is introduced at an acute angle against the flow of the intake air flowing through the intake passage 6. For this reason, the condensed water contained in the exhaust recirculation gas, which has a higher specific gravity than the exhaust recirculation gas, is easily affected by the pressure of the intake air flowing through the intake passage 6. As a result, the condensed water contained in the exhaust recirculation gas is easily pushed back toward the exhaust recirculation passage 12.

As shown in FIG. 6, the nipple 6b of the exhaust circulation passage 12 has an extension 6d that extends linearly from below, and a curved portion 6e that connects the extension 6d to the through hole 6c in a curved manner. That is, when viewed in the cross section of FIG. 6, the exhaust circulation passage 12 is arranged so that the inner circumferential surface 6f of the extension 6d on the front side F in the longitudinal direction Q does not intersect with the inner circumferential surface 6g of the intake passage 6. The exhaust circulation passage 12 is smoothly connected from the extension 6d to the through hole 6c by the curved portion 6e without a large change in inner diameter. In addition, the exhaust circulation passage 12 is connected to the through hole 6c without protruding into the intake passage 6. By arranging the exhaust circulation passage 12 in this way, even if condensed water flows into the intake passage 6, the condensed water is likely to return to the exhaust circulation passage 12. In this embodiment, the exhaust circulation passage 12 is arranged offset to the cylinder block 2 side (in this embodiment, the front side F in the longitudinal direction Q of the vehicle C) with respect to the intake passage 6. This allows the nipple 6b to be stored compactly without protruding behind the internal combustion engine 1. Furthermore, it is easier to ensure a sufficient distance between the internal combustion engine 1 and the dash panel (not shown) of the vehicle C, improving safety in the event of a collision of the vehicle C.

In addition, when the exhaust recirculation gas passes through the curved portion 6e, the condensed water, which has a higher specific gravity than the exhaust recirculation gas, is centrifuged and collides with the upper part of the inner surface of the curved portion 6e. The condensed water that collides with the upper part of the inner surface of the curved portion 6e runs down the inner surface of the curved portion 6e due to its own weight and heads toward the exhaust recirculation valve 14. This makes it possible to prevent the condensed water from flowing into the intake passage 6.

The curved portion 6e is bent along the rotation direction of the compressor 8b of the turbocharger 8. This makes it easier for the condensed water that has been centrifuged by the swirling flow to flow into the nipple 6b of the exhaust gas circulation passage 12. This makes it easier for the condensed water to return to the exhaust gas circulation passage 12.

The exhaust recirculation valve 14 is disposed on the exhaust recirculation passage 12. The exhaust recirculation valve 14 is provided to adjust the amount of exhaust recirculation gas introduced into the intake passage 6. The exhaust recirculation valve 14 is disposed below the turbocharger 8 and is disposed alongside the exhaust purification device 10 in the crankshaft extension direction (vehicle width direction P in this embodiment).

The cooling device 16 is a heat exchanger that is disposed on the exhaust recirculation passage 12 and cools the exhaust recirculation gas flowing through the exhaust recirculation passage 12 with a coolant. In this embodiment, the cooling device 16 is formed of a metal member such as stainless steel in a rectangular prism shape with a passage through which the coolant flows, and includes an inlet side 16a and an outlet side 16b. The cooling device 16 covers the periphery of the third passage 12c, and cools the exhaust recirculation gas by flowing the coolant around the third passage 12c. In this embodiment, the cooling device 16 is welded to the third passage 12c, and is integrally formed from the inlet flange 16c to the outlet side 16b.

As shown in Figures 2, 3, and 4, the cooling device 16 is arranged with its longitudinal direction aligned with the vehicle width direction P and is fixed to the cylinder block 2. The cooling device 16 is arranged at an incline such that the inlet side 16a approaches the cylinder block 2 as it approaches the exhaust purification device 10. In other words, the cooling device 16 is arranged with its longitudinal direction inclined in the fore-and-aft direction Q so that the inlet side 16a is forward F in the fore-and-aft direction Q of the outlet side 16b.

One side of the cooling device 16, including the inlet side 16a, is disposed between the exhaust purification device 10 and the cylinder block 2, and the other side including the outlet side 16b is disposed in a space S surrounded by the turbocharger 8, the exhaust purification device 10, and the exhaust recirculation valve 14 when viewed from the rear of the vehicle C (when viewed from the exhaust side of the internal combustion engine 1). From such a space S, the running wind passing between the upper part of the internal combustion engine 1 and the engine hood (not shown) of the vehicle C passes through the turbine 8a and then passes through. At this time, the heat from the exhaust purification device 10 is also carried away together with the running wind. In other words, the space S becomes part of a cooling passage using the running wind. The running wind that has passed through the space S passes behind the differential gear box 22 and passes to the bottom of the vehicle C. In particular, in the internal combustion engine 1 of this embodiment, the exhaust collector 4a is integrally formed with the cylinder head 4, and the outlet of the exhaust collector 4a is connected to the turbine 8a. In addition, the exhaust purification device 10 is offset forward in the crankshaft extension direction from the turbocharger 8 (to the right in the vehicle width direction P in this embodiment). This makes it easier for the wind to flow into the space S below the turbocharger 8 than in an internal combustion engine that uses an exhaust manifold instead of the exhaust collection section 4a and in which the exhaust purification device 10 is attached without being offset in the crankshaft extension direction from the exhaust manifold (for example, the internal combustion engine of Patent Document 1).

By arranging the cooling device 16 in this manner, the cooling device 16 can be arranged compactly. Furthermore, during cold start of the internal combustion engine 1, the cooling liquid flowing through the cooling device 16 is in a cooled state. However, because the cooling device 16 is arranged along the curved surface of the exhaust purification device 10, the cooling liquid receives heat from the exhaust purification device 10, and the temperature of the cooling liquid is likely to rise. On the other hand, because the outlet side 16b of the cooling device 16 is arranged in the space S, after the internal combustion engine 1 has warmed up, while the vehicle C is running, it is cooled by the running wind, and excessive heating of the cooling device 16 can be prevented.

The cooling device 16 is arranged in the crankshaft extension direction (the same direction as the vehicle width direction P in this embodiment), in the order of the exhaust recirculation valve 14, the cooling device 16, and the exhaust purification device 10. That is, the cooling device 16 is arranged between the exhaust recirculation valve 14 and the exhaust purification device 10 when viewed from the rear of the vehicle C. The cooling device 16 is cooled by the coolant, so the heat released from the exhaust purification device 10 is blocked by the cooling device 16. As a result, the temperature rise around the exhaust recirculation valve 14 can be suppressed.

A differential gear box 22, which is an example of a power transmission device, is disposed below the cooling device 16. This allows debris such as stones that fly from below the vehicle C to strike the differential gear box 22. This prevents the cooling device 16 from being damaged by the debris.

As shown in FIG. 4, the coolant supply passage 18 branches off from the thermostat case 4c attached to the cylinder head 4 and is connected to the cooling device 16 to supply coolant to the cooling device 16. As shown in FIGS. 2, 3, and 4, the coolant supply passage 18 passes from the right side of the exhaust recirculation valve 14 to the rear side and extends forward. The coolant supply passage 18 that extends forward passes between the cooling device 16 and the exhaust purification device 10 and is connected to a nipple that is arranged near the inlet side 16a of the cooling device 16. When the internal combustion engine 1 is started in a cold state, cold coolant flows through the coolant supply passage 18. However, by arranging the coolant supply passage 18 in this way, the coolant is more likely to receive heat from the exhaust purification device 10 and warm up.

As shown in FIG. 1, the coolant discharge passage 20 is connected to the heater device 24 from near the outlet side 16b of the cooling device 16. That is, when the internal combustion engine 1 is started in a cold state, the coolant is warmed by the heat of the exhaust purification device 10 and flows to the heater device 24. This makes it easier for the heater device 24 to obtain the heat of the coolant, and makes it easier to shorten the time it takes for the interior to warm up. That is, the heater performance is improved. In particular, in this embodiment, the supercharger 8 is a turbocharger type supercharger 8 having a turbine 8a. In such a supercharger 8, the thermal capacity of the turbine 8a is large, and the heat at the start of the internal combustion engine 1 is taken by the turbine 8a, which tends to deteriorate the heater performance. However, according to the internal combustion engine 1 of this embodiment, the cooling device 16 receives heat from the exhaust purification device 10, which tends to improve the heater performance.

In addition, the amount of exhaust recirculation gas introduced into the intake passage 6 is increasing due to the strengthening of fuel efficiency regulations in recent years. In particular, since the internal combustion engine 1 of this embodiment has a turbocharger 8, by introducing exhaust recirculation gas into the intake passage 6 upstream of the turbocharger 8, more exhaust recirculation gas can be introduced than by introducing exhaust recirculation gas downstream of the turbocharger 8. However, when a large amount of exhaust recirculation gas is introduced into the intake, it is necessary to cool the exhaust recirculation gas to prevent the intake temperature from increasing. When the exhaust recirculation gas is cooled, condensation water is also likely to occur. Furthermore, if the condensation water adheres to the compressor 8b, it is likely to cause a breakdown of the turbocharger 8. According to the internal combustion engine 1 of this embodiment, it is possible to prevent the condensation water from flowing out into the intake passage 6, and therefore it is easy to prevent the condensation water from adhering to the compressor 8b.

In addition, as the amount of exhaust recirculation gas introduced increases, the pressure loss also increases when the inner diameter of the exhaust recirculation passage 12 is narrowed. If the pressure loss increases, it becomes difficult to introduce the exhaust recirculation gas into the intake passage 6. However, according to the internal combustion engine 1 of this embodiment, the curved portion 6e smoothly connects the extension portion 6d to the through hole 6c without causing a large change in the inner diameter. This suppresses the pressure loss of the exhaust recirculation gas. As a result, the exhaust recirculation gas can be smoothly introduced into the intake passage 6.

As described above, the present disclosure provides an internal combustion engine 1 that allows condensed water to easily return to the exhaust recirculation passage 12 and makes it easy to introduce exhaust recirculation gas.

<Other embodiments>
Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

(a) In the above embodiment, the vehicle C is described as a front-wheel drive type with the internal combustion engine 1 mounted horizontally, but the present disclosure is not limited to this. The internal combustion engine 1, transmission 21, and differential gear box 22 may be arranged, for example, in a vehicle in which the crankshaft extends in the fore-and-aft direction of the vehicle C and the internal combustion engine 1 is mounted vertically. Furthermore, the vehicle C may be a four-wheel drive vehicle in which the differential gear box 22 is provided with a transfer that transmits power to the rear wheels. The differential gear box 22 may also be part of a transaxle housing in which the transmission 21 and the differential gear are integrally formed.

(b) In the above embodiment, the exhaust purification device 10 has been described using an example of a catalyst section 10a to which a three-way catalyst is applied, but the present disclosure is not limited to this. The exhaust purification device 10 may be a device such as a gasoline particulate filter or a diesel particulate filter that adsorbs soot.

(c) In the above embodiment, an example in which the exhaust recirculation passage 12 is divided into multiple passages has been described, but the present disclosure is not limited to this. The exhaust recirculation passage 12 may be provided so as to connect the outlet pipe 10c of the exhaust purification device 10 to the intake passage 6. In addition, the materials used for each passage of the exhaust recirculation passage 12 are not limited to these, and may be changed as appropriate.

(d) In the above embodiment, an example was described in which the inlet side 16a was disposed between the cylinder block 2 and the catalyst portion 10a of the exhaust purification device 10, and the outlet side 16b was disposed in the space S, but the present disclosure is not limited to this. It is sufficient that at least the side including the inlet side 16a of the cooling device 16 (one side) is disposed between the cylinder block 2 and the catalyst portion 10a of the exhaust purification device 10, and the remaining portion of the cooling device 16 (the other side) is disposed in the space S.

1: internal combustion engine, 2: cylinder block, 2a: cylinder, 2b: crankshaft
6: intake passage, 8: turbocharger, 10: exhaust purification device, 12: exhaust recirculation passage, 14: exhaust recirculation valve,
16: Cooling device, 16a: Inlet side, 16b: Outlet side, 18: Cooling liquid supply passage, 22: Differential gear box (an example of a power transmission device)
24: heater device, C: vehicle, G: vertical direction (cylinder extension direction)
P: Vehicle width direction (crankshaft extension direction)
Q: Anteroposterior direction S: Space

Claims (6)

An internal combustion engine mounted on a vehicle,
a cylinder block in which a cylinder is formed and which holds a crankshaft;
an intake passage for supplying intake air to the cylinder;
a supercharger that supercharges the intake air flowing through the intake passage;
an exhaust gas purification device disposed displaced in an extension direction of the crankshaft with respect to the turbocharger and extending in an extension direction of the cylinder;
an exhaust gas recirculation passage connected to the intake passage downstream of the exhaust gas purification device;
an exhaust gas recirculation valve disposed in the exhaust gas recirculation passage and displaced in an extension direction of the crankshaft with respect to the exhaust gas purification device;
a cooling device disposed in the exhaust gas recirculation passage and configured to cool the exhaust gas recirculation gas flowing through the exhaust gas recirculation passage with a cooling liquid;
Equipped with
the exhaust gas recirculation valve, the cooling device, and the exhaust gas purification device are arranged in this order along the crankshaft extension direction,
one side of the cooling device is disposed between the exhaust gas purification device and the cylinder block, and the other side is disposed in a space surrounded by the turbocharger, the exhaust gas purification device, and the exhaust gas recirculation valve, with a lower side of the turbocharger being between the exhaust gas recirculation valve and the exhaust gas purification device;
Internal combustion engine. a power transmission device of the vehicle is disposed below the cooling device;
2. The internal combustion engine of claim 1. The cooling device is disposed at an incline so as to approach the cylinder block as it approaches the exhaust purification device.
3. An internal combustion engine according to claim 1 or 2. a cooling liquid supply passage for supplying a cooling liquid to the cooling device;
the coolant supply passage passes between the exhaust gas purification device and the cooling device;
An internal combustion engine according to any one of claims 1 to 3. The exhaust gas recirculation passage is disposed so as to be inclined downward from the intake passage toward the exhaust gas purification device.
An internal combustion engine according to any one of claims 1 to 4. the vehicle has a heater device for heating an interior of the vehicle,
The cooling liquid flows through the cooling device and then flows to the heater device.
6. An internal combustion engine according to any one of claims 1 to 5.