Internal combustion engine

Abstract

To provide an internal combustion engine that enables reduction in the size of a cylinder head and improvement of flexibility of layout of a component mounted to a cooling water discharge port.SOLUTION: An engine 1 includes: a cylinder head cover 5 mounted to an upper part of a cylinder head 4; and an EGR device 11 for recirculating part of exhaust gas discharged from an exhaust gas collecting part 4b to an intake port 4a as EGR gas. The EGR device 11 includes upstream side EGR piping 12, an EGR cooler 13, an EGR valve 14, downstream side EGR piping 15 and an EGR passage part 26. The EGR passage part 26 is provided in the cylinder head cover 5.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to an internal combustion engine.

Background Art

[0002] Conventionally, a cylinder head having an EGR (Exhaust Gas Recirculation) passage is known. (See Patent Document 1).

[0003] The EGR passage is provided at an end in the longitudinal direction (cylinder bank direction) of the cylinder head and is surrounded by a water jacket through which cooling water flows.

[0004] At the other end in the longitudinal direction (cylinder bank direction) of the cylinder head, a cooling water outlet for discharging cooling water from the water jacket is formed, and a cooling water pipe is connected to the cooling water outlet. Thereby, the EGR gas flowing through the EGR passage can be cooled by the cooling water.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the conventional cylinder head, the EGR passage is installed at an end in the longitudinal direction of the cylinder head so as to be surrounded by the water jacket.

[0007] Therefore, it is necessary to provide the cooling water outlet of the cylinder head outside the EGR passage, which makes the cylinder head longer in the longitudinal direction and increases the size of the cylinder head.

[0008] Furthermore, since a cooling water pipe is attached to the cooling water outlet, if the cylinder head is enlarged, the distance between the cooling water pipe and the surrounding parts of the cylinder head will decrease, which may reduce the flexibility of the cooling water pipe layout.

[0009] This invention was made in view of the above circumstances, and aims to provide an internal combustion engine that can miniaturize the cylinder head and improve the freedom of layout for components attached to the coolant outlet. [Means for solving the problem]

[0010] The present invention relates to an internal combustion engine comprising: a cylinder head having a cooling water passage through which cooling water flows; an intake side wall having an air intake port for drawing in intake air; an exhaust side wall having an exhaust gas exhaust port for discharging exhaust gas; a cooling water discharge side wall connected to the cylinder row end of the intake side wall and the cylinder row end of the exhaust side wall, and having a cooling water discharge port for discharging cooling water from the cooling water passage; a cylinder head cover mounted on the upper part of the cylinder head; and an EGR device for recirculating a portion of the exhaust gas discharged from the exhaust gas exhaust port as EGR gas to the air intake port side, wherein the EGR device comprises an EGR passage section through which EGR gas flows; an EGR cooler for cooling the EGR gas; and an EGR valve for adjusting the flow rate of the EGR gas, wherein the EGR passage section A portion of the cylinder head cover is provided, and the EGR passage is located outside the coolant discharge side wall in the cylinder row direction. It is characterized by the following. [Effects of the Invention]

[0011] As described above, the present invention makes it possible to miniaturize the cylinder head and improve the freedom of layout for components attached to the cooling water outlet. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a left side view of an internal combustion engine according to one embodiment of the present invention. [Figure 2] Figure 2 is a front view of the cylinder head and cylinder head cover of an internal combustion engine according to one embodiment of the present invention. [Figure 3] Figure 3 is a left side view of the cylinder head and cylinder head cover of an internal combustion engine according to one embodiment of the present invention. [Figure 4] Figure 4 is a plan view of an internal combustion engine according to one embodiment of the present invention, showing the engine with the cylinder head cover removed. [Figure 5] Figure 5 is a plan view of the EGR housing portion of an internal combustion engine according to one embodiment of the present invention. [Figure 6] Figure 6 is a plan view of the EGR housing of an internal combustion engine according to one embodiment of the present invention, showing the state with the intake cam angle sensor and exhaust cam angle sensor removed. [Figure 7] Figure 7 is a cross-sectional view taken along the VII-VII line in Figure 5. [Modes for carrying out the invention]

[0013] An internal combustion engine according to one embodiment of the present invention comprises a cylinder head having a cooling water passage through which cooling water flows, an intake side wall having an air intake port for taking in intake air, an exhaust side wall having an exhaust gas exhaust port from which exhaust gas is discharged, a cooling water discharge side wall connected to the end of the intake side wall in the direction of the cylinder row and the end of the exhaust side wall in the direction of the cylinder row and having a cooling water discharge port for discharging cooling water from the cooling water passage, a cylinder head cover mounted on the upper part of the cylinder head, and an EGR device that recirculates a portion of the exhaust gas discharged from the exhaust gas exhaust port as EGR gas to the air intake port side, wherein the EGR device comprises an EGR passage section through which EGR gas flows, an EGR cooler for cooling the EGR gas, and an EGR valve for adjusting the flow rate of the EGR gas, and a portion of the EGR passage section is provided in the cylinder head cover.

[0014] As a result, the internal combustion engine according to one embodiment of the present invention can achieve a smaller cylinder head and improve the freedom of layout for components attached to the coolant outlet. [Examples]

[0015] Hereinafter, an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 to 7 are diagrams showing an internal combustion engine according to an embodiment of the present invention. In FIGS. 1 to 7, the up-down, front-back, and left-right directions are based on the internal combustion engine installed in a vehicle. The front-back direction of the vehicle is the front-back direction, the left-right direction (vehicle width direction) of the vehicle is the left-right direction, and the up-down direction (vehicle height direction) of the vehicle is the up-down direction.

[0016] First, the configuration will be described. In FIG. 1, an engine 1 is provided in an engine room (not shown) of a vehicle. The engine 1 includes an engine body 2 and a chain cover 10 (see FIG. 4).

[0017] The engine body 2 has a cylinder block 3, a cylinder head 4, a cylinder head cover 5, and an oil pan 6, and the chain cover 10 is connected to the right end portion of the engine body 2. The engine 1 of the present embodiment constitutes an internal combustion engine.

[0018] The cylinder block 3 is provided with a plurality of cylinders 3A (shown by phantom lines in FIG. 4), and the cylinders 3A are arranged in the vehicle width direction. Hereinafter, the arrangement direction (vehicle width direction) of the cylinders 3A is referred to as a cylinder row direction A.

[0019] Note that the engine 1 of the present embodiment is composed of a three-cylinder engine having three cylinders 3A, but the number of cylinders is not limited to three.

[0020] Each of the cylinders 3A houses a piston (not shown), and the piston is connected to a crankshaft 7 via a connecting rod (not shown) (see FIG. 1). The crankshaft 7 has a rotation center axis extending in the vehicle width direction and rotates around the rotation center axis. The engine 1 of the present embodiment is a horizontally opposed engine in which the crankshaft 7 extends in the vehicle width direction, and the vehicle is a FF (front engine · front drive) vehicle.

[0021] The piston reciprocates within cylinder 3A, thereby rotating the crankshaft 7 via the connecting rod. The cylinder head 4 has several intake ports 4a (see Figure 4) and an exhaust manifold 4b (see Figure 3), which are not shown.

[0022] Each intake port 4a is connected to a cylinder 3A, and intake air is introduced into the cylinder 3A. The exhaust manifold 4b is connected to each cylinder 3A through several exhaust ports (not shown).

[0023] In other words, each exhaust port extends from each cylinder 3A to the exhaust manifold 4b, and the exhaust manifold 4b collects the exhaust ports.

[0024] As shown by the dashed lines in Figure 2, the cylinder head 4 is provided with a cooling water passage 20, which extends from the right end to the left end of the cylinder head 4.

[0025] Cooling water is introduced into the right end of the cooling water passage 20 from a cooling water passage (not shown) formed in the cylinder block 3. The cooling water introduced into the cooling water passage 20 flows to the left along the cooling water passage 20. As a result, the cylinder head 4 is cooled by the cooling water. The cooling water passage 20 in this embodiment constitutes the cooling water passage.

[0026] As shown in Figure 4, the cylinder head 4 has an intake side wall 4A through which the intake port 4a opens, and an exhaust side wall 4B located on the opposite side (front side) from the intake side wall 4A, through which the exhaust manifold 4b opens.

[0027] As shown in Figure 3, the cylinder head 4 has a coolant discharge side wall 4C in which a coolant discharge port 4c is formed for discharging coolant from the coolant passage 20. The coolant discharge side wall 4C is connected to the left end of the intake side wall 4A (the end in the cylinder row direction A) and the left end of the exhaust side wall 4B (the end in the cylinder row direction A), and extends in the front-rear direction.

[0028] A cooling water distribution unit (not shown) is connected to the cooling water outlet 4c, and the cooling water distribution unit is connected by a branch pipe (not shown) to a radiator (not shown) and the cooling water inlet 13A of the EGR cooler 13 (see Figure 1).

[0029] The coolant discharged from the coolant outlet 4c is supplied to the radiator and the coolant inlet 13A of the EGR cooler 13 through the coolant branching unit and coolant pipes.

[0030] In this embodiment, the intake port 4a constitutes an air intake port for drawing in intake air, and the exhaust manifold 4b constitutes an exhaust gas outlet for discharging exhaust gas. That is, the cylinder head 4 has an intake side wall 4A having an intake port 4a and an exhaust side wall 4B having an exhaust manifold 4b.

[0031] As shown in Figure 1, an intake manifold 8 is attached to the intake side wall 4A. The intake manifold 8 has a surge tank 8A and three branch pipes 8B (one shown) corresponding to the number of cylinders 3A. An intake pipe (not shown) is connected to the surge tank 8A via a throttle body (not shown).

[0032] Intake air, purified by an air cleaner (not shown), is introduced into the intake manifold, and the intake air is then introduced into the surge tank 8A through the throttle body.

[0033] The throttle body houses a throttle valve (not shown), which adjusts the amount of intake air introduced into the surge tank 8A.

[0034] Multiple branch pipes 8B extend from the surge tank 8A to each intake port 4a, distributing the intake air introduced into the surge tank 8A to each intake port 4a.

[0035] An exhaust gas purification device 9 is attached to the intake side wall 4A. The exhaust gas burned in cylinder 3A is discharged from cylinder 3A through the exhaust port, collected in the exhaust manifold 4b, and then discharged from the exhaust manifold 4b to the exhaust gas purification device 9.

[0036] The exhaust gas purification device 9 purifies the exhaust gas discharged from the exhaust manifold 4b and discharges it into the atmosphere through an exhaust pipe (not shown).

[0037] Engine 1 is equipped with an EGR (Exhaust Gas Recirculation) device 11. The EGR device 11 comprises an upstream EGR pipe 12, an EGR cooler 13, an EGR valve 14, and a downstream EGR pipe 15.

[0038] The upstream end of the upstream EGR pipe 12 is connected to the exhaust gas purification device 9, and a portion of the exhaust gas from the exhaust gas purification device 9 is introduced into the upstream EGR pipe 12 as EGR gas. Here, upstream and downstream refer to the upstream and downstream directions in relation to the flow of intake air, exhaust gas, and EGR gas.

[0039] The EGR valve 14 is located downstream of the upstream EGR pipe 12, and the upstream EGR pipe 12 is located upstream of the EGR valve 14.

[0040] The downstream end of the upstream EGR pipe 12 is connected to the upstream end of the EGR cooler 13. The EGR cooler 13 has a cooling water inlet 13A for introducing cooling water into the EGR cooler 13 and a cooling water outlet 13B for discharging cooling water from the EGR cooler 13.

[0041] The EGR cooler 13 cools the EGR gas introduced from the upstream EGR pipe 12 by exchanging heat between the EGR gas and cooling water.

[0042] The downstream end of the EGR cooler 13 is connected to the EGR valve 14. The EGR valve 14 is connected to the EGR housing 25 and adjusts the flow rate of EGR gas flowing through the EGR passage 26, which will be described later.

[0043] The upstream end of the downstream EGR pipe 15 is connected to the EGR housing section 25, and the EGR gas introduced into the EGR housing section 25 is discharged into the downstream EGR pipe 15. The downstream end of the downstream EGR pipe 15 is connected to the surge tank 8A, and the EGR gas discharged into the downstream EGR pipe 15 is introduced into the surge tank 8A.

[0044] As shown in Figure 4, the cylinder head 4 is provided with an intake camshaft 16 and an exhaust camshaft 17, which extend parallel to the cylinder row direction A. The intake camshaft 16 and exhaust camshaft 17 are provided with multiple intake cams 16A and exhaust cams 17A.

[0045] The intake cam 16A and exhaust cam 17A are installed spaced apart in the cylinder row direction A, with one pair provided for every cylinder 3A.

[0046] The intake camshaft 16 and the exhaust camshaft 17 are rotatably supported by the cylinder head 4 by cam caps 18 and 19, respectively.

[0047] Specifically, journal bearings (not shown) are provided on the upper surface of the cylinder head 4, facing the cam caps 18 and 19. The intake camshaft 16 and exhaust camshaft 17 are rotatably mounted on the cylinder head 4, sandwiched between the journal bearing portion and the cam caps 18 and 19, respectively. In this embodiment, the intake camshaft 16 and exhaust camshaft 17 constitute the camshaft.

[0048] As shown in Figures 5 and 6, an EGR housing portion 25 is provided at the end (left end) of the cylinder head 4 in the cylinder row direction A. The EGR housing portion 25 is located on the opposite side of the chain cover 10 from the cylinder head cover 5. That is, the EGR housing portion 25 is adjacent to the cylinder head cover 5 in the cylinder row direction A.

[0049] The cylinder head cover 5 is made of resin, and the EGR housing section 25 is made of metal such as aluminum die-cast.

[0050] The EGR housing 25 constitutes the first cylinder head cover, and the cylinder head cover 5 constitutes the second cylinder head cover. The EGR housing 25 and the cylinder head cover 5 together constitute the cylinder head cover.

[0051] As shown in Figures 5 and 6, the EGR housing section 25 has a front wall 25A, a rear wall 25B, a left side wall 25C, and an upper wall 25D.

[0052] As shown in Figure 3, the front wall 25A is located on the exhaust side wall 4B of the cylinder head 4, and the rear wall 25B is located on the intake side wall 4A of the cylinder head 4.

[0053] As shown in Figures 5 and 6, the left side wall 25C connects the left end of the front wall 25A (the end in the cylinder row direction A) and the left end of the rear wall 25B (the end in the cylinder row direction A), and the upper wall 25D connects the upper end of the front wall 25A, the upper end of the rear wall 25B, and the upper end of the left side wall 25C.

[0054] In this embodiment, the front wall 25A constitutes the first side wall, the rear wall 25B constitutes the second side wall, and the left side wall 25C constitutes the third side wall.

[0055] The EGR housing section 25 is provided with an EGR passage section 26. The EGR passage section 26 is formed in a cylindrical shape, and an EGR passage 26a through which EGR gas flows is formed inside (see Figure 7). In this embodiment, the upstream EGR pipe 12, the downstream EGR pipe 15, and the EGR passage section 26 constitute the EGR passage section.

[0056] The EGR passage section 26 has an EGR gas inlet 26b and an EGR gas outlet 26c. The EGR gas inlet 26b is provided on the front wall 25A (see Figure 2), and the EGR gas outlet 26c is provided on the rear wall 25B.

[0057] The EGR gas inlet 26b is the front (upstream) opening end of the EGR passage 26a, and the EGR gas outlet 26c is the rear (downstream) opening end of the EGR passage 26a.

[0058] In this embodiment, the EGR passage 26 extends linearly in a direction perpendicular to the cylinder row direction A (front-to-back direction) and is located outside (to the left of) the intake side wall 4A in the cylinder row direction A. In other words, the EGR passage 26 is located away from the cylinder head cover 5 relative to the intake side wall 4A in the cylinder row direction A.

[0059] Furthermore, the EGR passage section 26 is not limited to extending in a straight line in a direction perpendicular to the cylinder row direction A, but may also extend at an inclination with respect to the cylinder row direction A. Note that "horizontal" includes directions that are close to horizontal, that is, directions that are slightly inclined with respect to the horizontal.

[0060] As shown in Figure 2, the front wall 25A is provided with a flange portion 25a, and an EGR gas inlet 26b is formed inside the flange portion 25a.

[0061] As shown in Figure 1, the flange portion 14a of the EGR valve 14 is attached to the flange portion 25a. An EGR gas outlet (not shown) is provided inside the flange portion 14a, and the EGR gas discharged from the EGR valve 14 is introduced into the EGR passage 26a through the EGR gas inlet 26b.

[0062] As shown in Figures 5 and 6, a flange portion 25b is provided on the rear wall 25B, and an EGR gas outlet 26c is formed inside the flange portion 25b.

[0063] As shown in Figure 1, the flange portion 25b is attached to the flange portion 15a of the downstream EGR pipe 15. An EGR gas inlet (not shown) is provided inside the flange portion 15a, and the EGR gas flowing through the EGR passage 26a is discharged to the downstream EGR pipe 15 through the EGR gas inlet of the flange portion 15a.

[0064] In other words, in this embodiment, the engine 1 has an EGR housing 25 attached to the left end of the cylinder head 4 above the cylinder head 4, and EGR gas is introduced from the exhaust side to the intake side through an EGR passage 26 provided in the EGR housing 25.

[0065] As shown in Figure 4, bosses 27A and 27B are provided at the front and rear ends of the left wall 25C, and the bosses 27A and 27B extend vertically along the left wall 25C. Bosses 27F and 27G are provided on the front wall 25A and the rear wall 25B, and the bosses 27F and 27G extend vertically along the front wall 25A and the rear wall 25B.

[0066] A bolt groove (not shown) is provided at the upper left end of the cylinder head 4. Bolts 41A are inserted through bosses 27A, 27B, 27F, and 27G, and bolts 41A are screwed into the bolt grooves of the cylinder head 4. In this way, the EGR housing 25 is fixed to the cylinder head 4.

[0067] As shown in Figure 4, a flange portion 4F is provided at the upper end of the cylinder head 4. The flange portion 4F is provided around the cylinder head 4, and the cylinder head 4 is open on the inside of the flange portion 4F. That is, an opening 4h is formed at the top of the cylinder head 4.

[0068] A flange portion 10F is provided at the upper end of the chain cover 10, and the flange portion 10F is connected to the flange portion 4F.

[0069] The EGR housing portion 25 is provided with a housing-side flange portion 25c, a front flange portion 25d, and a rear flange portion 25e.

[0070] As shown in Figure 4, the housing-side flange portion 25c extends from the front wall 25A to the rear wall 25B, adjacent to the upper wall 25D. In other words, the housing-side flange portion 25c is connected to the right end of the upper wall 25D (the end on the chain cover 10 side).

[0071] The housing-side flange portion 25c is provided with a curved portion 25p, which curves from the center of the housing-side flange portion 25c in the direction of extension (center in the front-rear direction) toward the left side wall 25C.

[0072] In this embodiment, the curved portion 25p of the upper wall 25D causes the width in the cylinder row direction A at the front-to-rear center of the upper wall 25D to be shorter than the width in the cylinder row direction A at the front of the upper wall 25D and the width in the cylinder row direction A at the rear of the upper wall 25D.

[0073] As a result, the area of ​​the flat portion in the front-to-rear center of the upper wall 25D is smaller than the area of ​​the front and rear sides of the upper wall 25D.

[0074] The front flange portion 25d is located at the upper end of the front wall 25A and extends from the front end of the housing-side flange portion 25c to the flange portion 4F, and is in contact with the flange portion 4F.

[0075] The rear flange portion 25e is located at the upper end of the rear wall 25B and extends from the rear end of the housing-side flange portion 25c to the flange portion 4F, and is in contact with the flange portion 4F.

[0076] As shown in Figures 2 and 3, a flange portion 5F is provided on the lower outer edge of the cylinder head cover 5, and the flange portion 5F extends along flange portions 4F, 10F, 25c, 25d, and 25e. That is, the flange portion 5F faces flange portions 4F, 10F, 25c, 25d, and 25e in the vertical direction.

[0077] As shown in Figure 4, the flange portion 4F has multiple boss portions 4D formed on it, and the boss portions 4D are spaced apart in the direction in which the flange portion 4F extends.

[0078] Multiple boss portions 10A are formed on the flange portion 10F, and the boss portions 10A are spaced apart in the direction in which the flange portion 10F extends (see Figure 2).

[0079] Bosses 27C, 27D, and 27E are provided on the upper wall 25D of the EGR housing section 25. The bosses 27C, 27D, and 27E protrude upward from the upper wall 25D and are connected to the housing-side flange section 25c.

[0080] As a result, the boss portions 27C, 27D, and 27E are connected to each other by the housing-side flange portion 25c. In this embodiment, the housing-side flange portion 25c constitutes the flange portion.

[0081] As shown in Figure 2, the flange portion 5F of the cylinder head cover 5 is provided with a plurality of boss portions 5A, and the boss portions 5A are spaced apart in the direction in which the flange portion 5F extends.

[0082] Multiple bosses 5A, 4D, 10A, and 27C, 27D, and 27E are aligned vertically. Bolts 41B and 41C are inserted through the multiple bosses 5A, 4D, 10A, and 27C, 27D, and 27E, and the cylinder head cover 5 is fixed to the cylinder head 4 by bolts 41B and 41C.

[0083] In other words, the cylinder head cover 5 is fixed across the cylinder head 4, the chain cover 10, and the EGR housing portion 25, and covers the opening 4h of the cylinder head 4.

[0084] As shown in Figure 6, mounting bosses 28A and 28B are provided on the upper wall 25D, and as shown in Figure 5, an exhaust cam angle sensor 31 and an intake cam angle sensor 32 are attached to the mounting bosses 28A and 28B, respectively.

[0085] The exhaust cam angle sensor 31 includes a sensor body 31A fixed to a mounting boss portion 28A by a bolt 41D, and a connector 31B attached to the upper end of the sensor body 31A.

[0086] The intake cam angle sensor 32 has a sensor body 32A fixed to a mounting boss portion 28B by a bolt 41D, and a connector 32B attached to the upper end of the sensor body 32A. The exhaust cam angle sensor 31 and the intake cam angle sensor 32 have the same configuration and are interchangeable.

[0087] As shown in Figure 7, the sensor body 31A of the exhaust cam angle sensor 31 is attached to the mounting boss portion 28A via a sealing member 29, which prevents water and foreign matter from entering the inside of the EGR housing portion 25 from between the sensor body 31A and the mounting boss portion 28A.

[0088] Furthermore, a sealing member (not shown) is interposed between the sensor body 32A and the mounting boss portion 28B of the intake cam angle sensor 32. The exhaust cam angle sensor 31 and the intake cam angle sensor 32 in this embodiment constitute a cam angle sensor.

[0089] As shown in Figure 4, intake-side sensing rotors 16S and exhaust-side sensing rotors 17S are attached to the left ends of the intake camshaft 16 and exhaust camshaft 17, respectively, and the intake-side sensing rotors 16S and exhaust-side sensing rotors 17S are located below the upper wall 25D of the EGR housing 25.

[0090] The outer circumferences of the intake-side sensing rotor 16S and the exhaust-side sensing rotor 17S are formed with protrusions (not shown), and these protrusions are formed in a unique pattern for each cylinder 3A.

[0091] The exhaust cam angle sensor 31 and the intake cam angle sensor 32 are positioned opposite the intake side sensing rotor 16S and the exhaust side sensing rotor 17S in the vertical direction, and the sensor body 31A detects the protrusions on the intake side sensing rotor 16S and the exhaust side sensing rotor 17S, thereby detecting the rotation angle (rotation phase) of the intake cam shaft 16 and the exhaust cam shaft 17.

[0092] Connectors 31B and 32B are connected to the controller via a wire harness (not shown), and information regarding the cam angle detected by the sensor bodies 31A and 32A is transmitted from connectors 31B and 32B through the wire harness to the controller (not shown).

[0093] As shown in Figures 6 and 7, the mounting bosses 28A and 28B are connected to the EGR passage 26.

[0094] As shown in Figure 7, the lower end portion 28a of the mounting boss portions 28A and 28B is located above the lower end portion 26d of the EGR passage portion 26 and below the upper end portion 26e of the EGR passage portion 26, and the upper end portion 28b of the mounting boss portions 28A and 28B is located above the upper end portion 26e of the EGR passage portion 26.

[0095] In other words, the upper end portion 26e of the EGR passage portion 26 is located above the lower end portion 28a of the mounting boss portions 28A and 28B.

[0096] Although the mounting boss portion 28B is not shown in Figure 7, the positional relationship between the mounting boss portion 28B and the EGR passage portion 26 is the same as the positional relationship between the mounting boss portion 28A and the EGR passage portion 26. Furthermore, the mounting boss portion 28B is located behind (rear of) the mounting boss portion 28A in Figure 7. Therefore, in Figure 7, the mounting boss portion 28B, located behind the mounting boss portion 28A, is indicated by a dashed line.

[0097] As shown in Figure 4, boss portion 27C is installed on the EGR passage portion 26 side relative to boss portions 27D and 27E, and is connected to the EGR passage portion 26.

[0098] The boss portion 27D is provided on the upper wall 25D on the front wall 25A side relative to the boss portion 27C, and is located on the front wall 25A side than the mounting boss portion 28A.

[0099] The boss portion 27E is provided on the upper wall 25D on the rear wall 25B side relative to the boss portion 27C, and is located on the rear wall 25B side of the mounting boss portion 28B.

[0100] In this embodiment, the boss portion 27C constitutes a fastening portion and a first fastening portion, the boss portion 27D constitutes a fastening portion and a second fastening portion, the boss portion 27E constitutes a fastening portion and a third fastening portion, and the bolt 41C constitutes a fastener.

[0101] The mounting boss portion 28A is installed between the boss portions 27C and 27D. Specifically, the mounting boss portion 28A is installed between the boss portions 27C and 27D such that it passes through a virtual straight line 42A connecting the boss portions 27C and 27D. In other words, the mounting boss portion 28A is sandwiched between the boss portions 27C and 27D.

[0102] The mounting boss portion 28B is installed between the boss portions 27C and 27E. Specifically, the mounting boss portion 28B is installed between the boss portions 27C and 27E such that it passes through a virtual straight line 42B connecting the boss portions 27C and 27E. In other words, the mounting boss portion 28B is sandwiched between the boss portions 27C and 27E.

[0103] Mounting boss portion 28A overlaps with boss portion 27D in the cylinder row direction A, and mounting boss portion 28B overlaps with boss portion 27E in the cylinder row direction A. In other words, mounting boss portions 28A, 28B, boss portion 27D, and boss portion 27E overlap in the cylinder row direction A.

[0104] In other words, the mounting bosses 28A, 28B, boss 27D, and boss 27E are installed side by side in a direction perpendicular to the cylinder row direction A (front-to-back direction).

[0105] Next, the effects of engine 1 in this embodiment will be explained. The engine 1 of this embodiment includes a cylinder head 4, the cylinder head 4 having a cooling water passage 20 through which cooling water flows, an intake side wall 4A having an intake port 4a for drawing in intake air, an exhaust side wall 4B having an exhaust manifold 4b through which exhaust gas is discharged, and a cooling water discharge side wall 4C connected to the left end of the intake side wall 4A and the left end of the exhaust side wall 4B, and having a cooling water outlet 4c through which cooling water is discharged from the cooling water passage 20.

[0106] Furthermore, the engine 1 includes a cylinder head cover 5 mounted on the upper part of the cylinder head 4, and an EGR device 11 that recirculates a portion of the exhaust gas discharged from the exhaust manifold 4b as EGR gas to the intake port 4a side.

[0107] The EGR device 11 includes an upstream EGR pipe 12, an EGR cooler 13, an EGR valve 14, a downstream EGR pipe 15, and an EGR passage 26, the EGR passage 26 being provided on the cylinder head cover 5.

[0108] This allows the coolant outlet 4c of the cylinder head 4 to be positioned inside the cylinder head 4 relative to the EGR passage 26, that is, on the cylinder head cover 5 side relative to the EGR passage 26. As a result, the dimension of the cylinder head 4 in the cylinder row direction A can be shortened, and the cylinder head 4 can be made more compact.

[0109] Furthermore, by miniaturizing the cylinder head 4, the distance between the surrounding components of the engine 1 and the cylinder head 4 can be increased. This improves the flexibility of the layout of components such as the cooling water pipes connected to the cooling water outlet 4c of the cylinder head 4, and the cooling water branching units and branching pipes connected to the cooling water pipes.

[0110] Furthermore, the engine 1 of this embodiment includes an EGR housing section 25 having an EGR passage section 26, and a cylinder head cover 5 adjacent to the EGR housing section 25 in the cylinder row direction A.

[0111] The EGR housing section 25 is composed of a front wall 25A located on the exhaust side wall 4B side, a rear wall 25B located on the intake side wall 4A side, a left side wall 25C located on the coolant discharge side wall, and an upper wall 25D connected to the upper end of the front wall 25A, the upper end of the rear wall 25B, and the upper end of the left side wall 25C.

[0112] In addition, the EGR passage section 26 has an EGR gas inlet 26b provided on the front wall 25A for introducing EGR gas into the EGR passage, and an EGR gas outlet 26c provided on the rear wall 25B for discharging EGR gas from the EGR passage 26a.

[0113] By providing the cylinder head cover 5 and EGR housing section 25, which are divided into two parts, and by providing an EGR passage section 26 in the EGR housing section 25, the cylinder head 4 can be accessed from the outside with the EGR housing section 25 attached to it by removing the cylinder head cover 5 from the cylinder head 4.

[0114] Therefore, the cylinder head 4 can be accessed from the outside without disassembling the EGR device 11. As a result, the workability when performing any work related to the cylinder head 4 (for example, maintenance work on the intake camshaft 16 or exhaust camshaft 17) can be improved.

[0115] Furthermore, in the engine 1 of this embodiment, the EGR housing 25 is made of metal, and the cylinder head cover 5 is made of resin.

[0116] Since metal dissipates heat more easily than resin, by providing the EGR passage 26 through which the EGR gas flows in a metal EGR housing 25, the heat from the EGR gas can be dissipated from the EGR housing 25, thereby promoting the cooling of the EGR gas.

[0117] On the other hand, since the cylinder head cover 5 is made of resin, it has a lower thermal conductivity than metal. Therefore, heat is less likely to be transferred from the high-temperature cylinder head 4 to the cylinder head cover 5, and less likely to be transferred from the cylinder head cover 5 to the EGR housing 25.

[0118] As a result, the cooling of the EGR gas flowing through the EGR passage 26 can be prevented from being hindered by the heat of the cylinder head cover 5, thereby promoting the cooling of the EGR gas.

[0119] Furthermore, according to the engine 1 of this embodiment, the EGR passage section 26 is located outside (to the left) of the coolant discharge side wall 4C in the cylinder row direction A.

[0120] Here, a coolant branching unit is connected to the coolant outlet 4c of the cylinder head 4, and a branch pipe is connected to the coolant branching unit. Therefore, if the cylinder head 4 is enlarged, the distance between the cylinder head 4 and the surrounding parts of the cylinder head 4 becomes shorter, which negatively affects the layout of these coolant branching unit and branch pipes connected to the coolant outlet 4c.

[0121] Since the cylinder head cover 5 is located on top of the engine 1, even if the EGR passage 26 is formed outside (to the left) of the coolant discharge side wall 4C in the cylinder row direction A, it is possible to suppress a decrease in the degree of freedom of layout of the parts connected to the coolant discharge port 4c.

[0122] Furthermore, by positioning the EGR passage 26 outside (to the left) of the coolant discharge side wall 4C in the cylinder row direction A, the EGR passage 26 can be positioned to protrude to the left from the cylinder head 4.

[0123] This allows the EGR passage 26 to be separated from the coolant discharge side wall 4C in the cylinder row direction A, thereby suppressing the EGR passage 26 from being affected by the heat of the cylinder head 4. As a result, the cooling of the EGR gas can be promoted.

[0124] While embodiments of the present invention have been disclosed, it will be apparent to those skilled in the art that modifications can be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims. [Explanation of Symbols]

[0125] 1...Engine (internal combustion engine), 4...Cylinder head, 4A...Intake side wall, 4a...Intake port (air intake), 4B...Exhaust side wall, 4C...Coolant discharge side wall, 4b...Exhaust manifold (exhaust gas outlet), 5...Cylinder head cover (second cylinder head cover), 11...EGR device, 12...Upstream EGR piping (EGR passage), 13...EGR cooler, 14...EGR valve, 15...Downstream EGR piping (EGR passage), 20...Coolant passage, 25...EGR housing (first cylinder head cover), 25A...Front wall (first side wall), 25B...Rear wall (second side wall), 25C...Left side wall (third side wall), 25D...Top wall, 26...EGR passage, 26b...EGR gas inlet, 26c...EGR gas outlet

Claims

1. A cylinder head having a cooling water passage through which cooling water flows, an intake side wall having an air intake port for drawing in intake air, an exhaust side wall having an exhaust gas outlet for discharging exhaust gas, and a cooling water discharge side wall connected to the cylinder row end of the intake side wall and the cylinder row end of the exhaust side wall, and having a cooling water discharge port for discharging cooling water from the cooling water passage, A cylinder head cover attached to the upper part of the aforementioned cylinder head, The system includes an EGR device that recirculates a portion of the exhaust gas discharged from the exhaust gas outlet back to the air intake port as EGR gas. The EGR system is an internal combustion engine comprising an EGR passage through which EGR gas flows, an EGR cooler for cooling the EGR gas, and an EGR valve for adjusting the flow rate of the EGR gas, A portion of the EGR passage is provided in the cylinder head cover, An internal combustion engine characterized in that the EGR passage is provided outside the coolant discharge side wall in the cylinder row direction.

2. The cylinder head cover comprises a first cylinder head cover having the EGR passage portion and a second cylinder head cover adjacent to the first cylinder head cover in the cylinder row direction, The first cylinder head cover is configured to include a first side wall located on the exhaust side wall side, a second side wall located on the intake side wall side, a third side wall located on the coolant discharge side wall side, and an upper wall connected to the upper end of the first side wall, the upper end of the second side wall, and the upper end of the third side wall. The internal combustion engine according to claim 1, characterized in that the EGR passage section has an EGR gas inlet provided in the first side wall for introducing EGR gas into the EGR passage section, and an EGR gas outlet provided in the second side wall for discharging EGR gas from the EGR passage section.

3. The internal combustion engine according to claim 2, characterized in that the first cylinder head cover is made of metal and the second cylinder head cover is made of resin.

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