JP2009079552A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the volume of a path for passing an exhaust gas from an exhaust valve to an exhaust brake valve by restraining temperature rise of the exhaust brake valve. <P>SOLUTION: A internal combustion engine 1 has different exhaust ports 4 comprising a plurality of cylinders 1s assembled at an exhaust path assembly part 14 for forming an exhaust manifold 15 in a cylinder head 1H. A first exhaust side cooling medium path 31 and a second exhaust side cooling medium path 32 are provided in the periphery of the exhaust ports 4 for cooling down the exhaust gas Ex passing through the exhaust ports 4 by supplying cooling water CF in the first exhaust side cooling medium path 31 and the second exhaust side cooling medium path 32. A valve member 12V of the exhaust brake valve is disposed in the exhaust path assembly part 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an internal combustion engine provided with a so-called exhaust brake.

  The exhaust brake is connected to a combustion chamber of an internal combustion engine, and closes an exhaust brake valve provided in the middle of an exhaust pipe for discharging exhaust gas after combustion of a mixture of fuel and air from the combustion chamber. The exhaust pressure in the combustion chamber is increased to generate a braking force. Since the exhaust brake can generate a stronger braking force than a normal engine brake, it is applied to a vehicle having a large mass such as a truck or a bus. Since the exhaust brake valve is provided in the exhaust passage, it is exposed to high temperature exhaust gas. Patent Document 1 discloses a technique for cooling an exhaust brake valve provided in the middle of an exhaust pipe.

JP-A-6-221190 (0006, FIG. 1)

  By the way, since the exhaust brake valve provided in the middle of the exhaust pipe is exposed to high-temperature exhaust gas and raises its temperature as described above, the influence of heat on components such as the valve body and the seal member of the exhaust brake valve is suppressed. Therefore, it is generally disposed downstream of the exhaust passage. For this reason, there is a problem that the volume of the passage through which the exhaust gas passes from the exhaust valve to the exhaust brake valve increases, and the response of the exhaust brake is poor. Further, since the surface area and heat capacity of the exhaust passage are increased, there is a problem that it takes time to warm up the engine when the internal combustion engine is cold started. Moreover, in the method of cooling the exhaust brake valve using a part of the air from the supercharger as in the technique disclosed in Patent Document 1, the structure is complicated and the application target includes the supercharger. There is a problem that it is limited to an internal combustion engine.

  The present invention has been made in view of the above, and provides an internal combustion engine that suppresses the temperature rise of an exhaust brake valve and can further reduce the volume of a passage through which exhaust gas passes from the exhaust valve to the exhaust brake valve. With the goal.

  In order to solve the above-described problems and achieve the object, an internal combustion engine according to the present invention includes a cylinder head attached to one end of the cylinder in an internal combustion engine in which a piston reciprocates in the cylinder, An exhaust passage that is provided inside the cylinder and communicates with a combustion space in which a mixture of fuel and air burns and an outside of the cylinder head, and is formed around the exhaust passage. An exhaust side cooling medium passage that cools the combustion gas after combustion of the air-fuel mixture that passes through the exhaust passage, and is disposed downstream of the exhaust passage in the flow direction of the combustion gas and passes through the exhaust passage. And a gas flow rate adjusting means for changing the gas flow rate.

  In this internal combustion engine, a cooling medium is caused to flow through an exhaust side cooling medium passage provided around an exhaust passage in the cylinder head to cool the combustion gas after the air-fuel mixture burns. As a result, the temperature of the combustion gas after the air-fuel mixture is combusted decreases, so that the temperature rise of the exhaust brake valve provided in the passage through which the combustion gas after the air-fuel mixture combusts can be suppressed. As a result, the exhaust valve The volume of the passage through which exhaust gas passes from the exhaust brake valve to the exhaust brake valve can be further reduced.

  In order to solve the above-described problems and achieve the object, an internal combustion engine according to the present invention includes a cylinder head attached to one end of the cylinder in an internal combustion engine in which a piston reciprocates in the cylinder, A plurality of exhaust passages that communicate with the outside of the cylinder head and a combustion space that is provided inside the cylinder and in which an air-fuel mixture of fuel and air burns, and is different among the plurality of exhaust passages. The at least two exhaust passages connected to the combustion space are formed around an exhaust passage collecting portion that collects in the cylinder head and a plurality of the exhaust passages, and pass through the exhaust passage. An exhaust side cooling medium passage for cooling the combustion gas after the combustion of the gas, and disposed downstream of the exhaust passage in the flow direction of the combustion gas, Characterized in that it comprises a gas flow rate adjusting means for changing the flow rate of the gas passing through the gas passage, a.

  In this internal combustion engine, a cooling medium is caused to flow through an exhaust side cooling medium passage provided around a plurality of exhaust passages in the cylinder head to cool the combustion gas after the air-fuel mixture burns. Further, this reduces the temperature of the combustion gas after the air-fuel mixture is combusted, so that the temperature rise of the exhaust brake valve provided in the passage through which the combustion gas after the air-fuel mixture burns can be suppressed. The volume of the passage through which the exhaust gas passes from the exhaust valve to the exhaust brake valve can be further reduced.

  As a desirable mode of the present invention, in the internal combustion engine, it is preferable that all the exhaust passages gather in one exhaust passage collecting portion in the cylinder head.

  As a desirable aspect of the present invention, in the internal combustion engine, the gas flow rate adjusting means is preferably disposed in the exhaust passage collecting portion.

  As a desirable mode of the present invention, in the internal combustion engine, it is preferable that the exhaust side cooling medium passage surrounds at least a part of the gas flow rate adjusting means.

  In a preferred aspect of the present invention, in the internal combustion engine, the gas flow rate adjusting means is configured to set the gas flow rate adjusting means before the warming up of the internal combustion engine is completed more than after the warming up of the internal combustion engine is completed. It is preferable to reduce the flow rate of the passing gas.

  The present invention can suppress the temperature rise of the exhaust brake valve and reduce the volume of the passage through which the exhaust gas passes from the exhaust valve to the exhaust brake valve.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the best mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. The present invention can be applied to both a spark ignition type internal combustion engine and a diesel type internal combustion engine.

  In this embodiment, in an internal combustion engine, as a passage through which an exhaust passage provided in the cylinder head flows a cooling medium for cooling a gas after the mixture is burned, that is, exhaust gas, which passes through the exhaust passage. A gas flow rate adjusting means that includes an exhaust side cooling medium passage and changes the flow rate of the gas passing through the exhaust passage downstream of the exhaust passage in the flow direction of the combustion gas, that is, between the exhaust passage and the atmosphere. There is a feature in providing. Then, the exhaust gas brake is operated by operating the gas flow rate adjusting means to reduce the flow rate of the gas flowing through the exhaust passage.

  FIG. 1 is a cross-sectional view of one cylinder showing the configuration of the internal combustion engine according to the present embodiment. FIG. 2 is a schematic diagram showing a cylinder head of the internal combustion engine according to the present embodiment. FIG. 3 is a schematic view showing the configuration of the exhaust brake valve provided in the internal combustion engine according to the present embodiment, which is a view taken along the line XX of FIG. FIG. 4 is a schematic diagram illustrating a configuration of a cooling system included in the internal combustion engine according to the present embodiment. FIG. 5 is a schematic diagram showing another configuration example of the internal combustion engine according to the present embodiment.

  First, the overall configuration of the internal combustion engine according to the present embodiment will be briefly described. An internal combustion engine 1 shown in FIGS. 1 and 2 is an internal combustion engine that is operated using a fuel containing hydrocarbons such as gasoline and light oil, and a so-called reciprocating internal combustion engine in which a piston 7 reciprocates in a cylinder 1s. It is. The cylinder 1 s is a cylindrical space provided inside the cylinder block 10. The cylinder block has a cylinder head 1H attached to one end and a crankcase 16 attached to the other end. That is, the cylinder head 1H is attached to one end of the cylinder 1s, and the crankcase 16 is attached to the other end.

  A space surrounded by the inner wall of the cylinder 1s, the piston 7, and the cylinder head 1H is a combustion space 1B in which a mixture of fuel and air is combusted. Thus, the combustion space 1B is provided inside the cylinder 1s. The piston 7 is driven by the combustion pressure of the air-fuel mixture combusted in the combustion space 1B.

  An intake port 3 that forms an intake passage for guiding the air Air to the combustion space 1B is connected to the combustion space 1B. The combustion space 1B is connected to an exhaust port 4 that forms an exhaust passage for discharging the combustion gas after combustion of the air-fuel mixture in the combustion space 1B, that is, the exhaust gas Ex, from the combustion space 1B. The intake port 3 communicates the combustion space 1B with the outside of the cylinder head 1H. Further, the exhaust port 4 communicates the combustion space 1B with the outside of the cylinder head 1H. As shown in FIG. 2, both the intake port 3 and the exhaust port 4 are formed integrally with the cylinder head 1H in the cylinder head 1H.

  The internal combustion engine 1 includes a port injection valve 13 that injects fuel f into an intake port 3 that is a part of an intake passage. The fuel f is supplied by the port injection valve 13. The internal combustion engine 1 may be a so-called direct injection internal combustion engine including a direct injection fuel injection valve that directly injects the fuel f into the combustion space 1B.

  The fuel f injected from the port injection valve 13 forms a fuel spray fm in the intake port 3 and forms an air-fuel mixture with the air Air introduced into the intake port 3. This air-fuel mixture flows between the intake valve 5i and the opening of the intake port 3 of the combustion space 1B and flows into the combustion space 1B. The air-fuel mixture in the combustion space 1B compressed by the rise of the piston 7 is ignited and burned by the discharge from the spark plug 2 attached to the cylinder head 1H before the piston 7 reaches the top dead center.

  The piston 7 reciprocates due to the combustion pressure when the air-fuel mixture burns. This reciprocating motion is transmitted to the crankshaft 8 via the connecting rod 9, where it is converted into a rotational motion and taken out as an output of the internal combustion engine 1. The air-fuel mixture after combustion becomes exhaust gas Ex, passes between the exhaust valve 5e and the opening of the exhaust port 4 of the combustion space 1B, and is discharged to the exhaust port 4. The intake valve 5i and the exhaust valve 5e are opened and closed by an intake cam 6i and an exhaust cam 6e, respectively.

  As shown in FIG. 1, a crank angle sensor 52 that detects the rotation angle of the crankshaft 8 is attached to the internal combustion engine 1. Further, the position of the intake cam 6i is detected by the cam position detection sensor 54, and the position of the piston 7 is determined based on this detection signal. Based on detection signals from the crank angle sensor 52 and the cam position detection sensor 54, an engine ECU (Electronic Control Unit) 50 determines the fuel injection timing of the port injection valve 13 and the discharge timing of the spark plug 2, that is, the ignition timing. The internal combustion engine 1 is attached with sensors for acquiring information necessary for controlling the operation of the internal combustion engine 1, such as an air flow sensor 53 and an accelerator opening sensor 55. The engine ECU 50 controls the operation of the internal combustion engine 1 based on signals from these various sensors.

  The cylinder block 10 including the cylinder 1s is provided with a cylinder block water jacket (cylinder block cooling medium passage) 11, which is a cooling medium for cooling the internal combustion engine 1 during operation of the internal combustion engine 1. Some cooling water circulates to cool the internal combustion engine 1. The cooling water is sent into the water jacket 11 by the water pump 30. Note that a part of the output of the internal combustion engine 1 may be extracted from the crankshaft 8 of the internal combustion engine 1 to drive the water pump 30, or a dedicated electric motor may be prepared to drive the water pump 30.

  As shown in FIG. 2, the internal combustion engine 1 includes a plurality of cylinders 1s. In FIG. 2, the internal combustion engine 1 is a so-called in-line 4-cylinder internal combustion engine in which four cylinders 1s are arranged in series, but the number of cylinders and the arrangement of the cylinders are not limited to this. In the present embodiment, the exhaust ports 4 connected to the combustion spaces 1B in the respective cylinders 1s provided in the internal combustion engine 1 gather in the cylinder head 1H. A portion (exhaust passage collecting portion) 14 where the respective exhaust ports 4 gather opens into the cylinder head 1H. Thus, in the internal combustion engine 1, the exhaust manifold 15 is formed in the cylinder head 1H.

  Here, the exhaust passage collecting portion 14 constitutes a part of the exhaust passage. In the present embodiment, the exhaust ports 4 are gathered by one exhaust passage collecting portion 14 in the cylinder head 1H, but at least two exhaust ports 4 connected to different combustion spaces 1B can be gathered together. That's fine. For example, in the internal combustion engine 1 shown in FIG. 2, the exhaust ports 4 connected to the two combustion spaces 1B are gathered in the cylinder head 1H, and the exhaust ports 4 connected to the remaining two combustion spaces 1B You may make it communicate with the exterior of the cylinder head 1H, without gathering in the head 1H. In the cylinder head 1H, it is preferable to collect the exhaust ports 4 by one exhaust passage assembly portion 14 because the volume of the passage through which the exhaust gas Ex passes can be further reduced.

  In the present embodiment, as shown in FIGS. 1, 2, and 3, the exhaust brake valve 12 is disposed in the exhaust passage collecting portion 14. The exhaust brake valve 12 includes a valve body 12V provided in the exhaust passage assembly 14 and an exhaust brake actuator 12A which is a valve body opening / closing means for opening and closing the valve body 12V. The valve body 12V changes the flow rate of the gas (including the exhaust gas Ex) exhausted from the combustion space 1B of the internal combustion engine 1 by changing the passage cross-sectional area of the exhaust passage collecting portion 14.

  Thus, the valve body 12V functions as a gas flow rate adjusting means that changes the flow rate of the gas discharged from the combustion space 1B and passing through the exhaust port 4 that is an exhaust passage provided in the cylinder head 1H. Thus, in the present embodiment, the gas flow rate is set in the exhaust gas passage assembly 14 located on the downstream side in the flow direction of the combustion gas after the air-fuel mixture burns, that is, the exhaust gas Ex, from the exhaust port 4 of the internal combustion engine 1. The valve body 12V which is an adjustment means is arrange | positioned. That is, the valve body 12V which is a gas flow rate adjusting means is disposed between the exhaust port 4 and the atmosphere.

  When the valve body 12V is closed, the exhaust pressure of the gas discharged from the combustion space 1B increases. As a result, the internal combustion engine 1 generates a braking force on the vehicle on which the internal combustion engine 1 is mounted, and the exhaust brake operates. Since the exhaust pressure of the gas discharged from the combustion space 1B changes by adjusting the opening of the valve body 12V, the braking force can be adjusted by the exhaust brake valve 12. As shown in FIG. 1, the exhaust brake actuator 12A is connected to an engine ECU 50, and the operation is controlled by the engine ECU 50. When operating the exhaust brake, the exhaust brake switch 51 connected to the engine ECU 50 is turned ON. Then, since the exhaust brake actuator 12A closes the valve body 12V, the exhaust brake operates.

  As shown in FIGS. 1 and 3, the valve body 12V is a circular plate. A valve body drive shaft 12S is attached to the valve body 12V along the radial direction of the valve body 12V through the center of the valve body 12V. The operation of the exhaust brake actuator 12A is transmitted to the valve body 12V via the valve body drive shaft 12S, and the valve body 12V opens and closes the exhaust passage collecting portion 14. Both end portions of the valve body drive shaft 12S are supported by bearings 12B. In the present embodiment, the valve body drive shaft 12S is arranged in parallel with the central axis of the cylinder 1s shown in FIG. 1, but the arrangement of the valve body drive shaft 12S is not limited to this. For example, the valve body drive shaft 12S may be orthogonal to the central axis of the cylinder 1s shown in FIG.

  The end on the side where the valve body drive shaft 12S is connected to the exhaust brake actuator 12A protrudes from the cylinder head 1H. With such a configuration, it is necessary to prevent the exhaust gas Ex passing through the exhaust passage collecting portion 14 from leaking from the portion where the valve body drive shaft 12S protrudes from the cylinder head 1H. A seal 12Se is provided.

  As shown in FIGS. 2, 3, and 4, in the cylinder head 1 </ b> H of the internal combustion engine 1, a cooling medium passage (exhaust side cooling medium passage) is formed around the exhaust port 4 and the exhaust passage collecting portion 14. In the present embodiment, the exhaust side cooling medium passage is composed of a first exhaust side cooling medium passage 31 and a second exhaust side cooling medium passage 32. Cooling water CF for cooling the internal combustion engine 1 is supplied to the first exhaust side cooling medium passage 31 and the second exhaust side cooling medium passage 32. A cooling medium passage (intake side cooling medium passage) 24 is also provided on the intake port 3 side, and the cooling water CF is supplied to cool the intake side of the cylinder head 1H. Here, the cooling system of the internal combustion engine 1 will be described with reference to FIG.

  As shown in FIG. 4, a cylinder block cooling passage 28 is formed in the cylinder block 10 of the internal combustion engine 1. The first exhaust side cooling medium passage 31 and the second exhaust side cooling medium passage 32 formed in the cylinder head 1 </ b> H of the internal combustion engine 1 are connected to a cooling medium inlet by a cooling medium branch passage 29 provided in the internal combustion engine 1. The cooling water CF flowing in from 1i is branched and supplied.

  The cooling water CF, which has been heated through the first exhaust-side cooling medium passage 31 and the second exhaust-side cooling medium passage 32, has a second cooling medium recovery passage 25 connected to the exhaust-side second cooling medium outlet 1ei, and It is discharged into the first cooling medium recovery passage 23 connected to the exhaust side first cooling medium outlet 1ee. The second cooling medium recovery passage 25 and the first cooling medium recovery passage 23 gather at a cooling medium recovery passage 26 connected to the cooling medium inlet 22 i of the radiator 22. The cooling water CF that flows into the radiator 22 from the cooling medium inlet 22i through the cooling medium recovery passage 26 is cooled by the radiator 22 that is a cooling medium heat exchanger. That is, in the process of exchanging heat between the cooling water CF passing through the radiator 22 and the cooling air, the heat of the raised cooling water CF moves to the cooling air, and the cooling water CF is cooled.

  The cooling medium outlet 22 e of the radiator 22 and the cooling medium inlet 1 i of the internal combustion engine 1 are connected by a cooling medium supply passage 27. The cooling medium supply passage 27 is provided with a water pump 30 which is a cooling medium supply means. The water pump 30 supplies the cooling water CF cooled by the radiator 22 to the internal combustion engine 1. With such a configuration, the cooling water CF that has cooled the exhaust gas that passes through the exhaust port 4 formed in the cylinder head 1H of the internal combustion engine 1 is recovered and cooled to the radiator 22, and is again returned to the internal combustion engine 1 by the water pump 30. Supply.

  A first exhaust side cooling medium passage 31 and a second exhaust side cooling medium passage 32 are formed as exhaust side cooling medium passages around the exhaust port 4 and the exhaust passage collecting portion 14 of the cylinder head 1H of the internal combustion engine 1, and the cooling water By flowing CF, the exhaust gas Ex passing through the exhaust port 4 constituting the exhaust passage is cooled. Thereby, the temperature rise of the components of the exhaust brake valve 12 such as the valve body 12V, the bearing 12B that supports the valve body 12V, and the seal 12Se that suppresses exhaust gas leakage can be suppressed, and the deterioration of durability can be suppressed. As a result, the volume of the passage through which the exhaust gas Ex passes from the exhaust valve 5e to the exhaust brake valve 12 shown in FIG. 1 can be further reduced. Moreover, since the temperature rise of the valve body 12V, the bearing 12B, and the seal 12Se is suppressed, it is not always necessary to use an expensive material having high heat resistance. Therefore, the manufacturing cost of the valve body 12V, the bearing 12B, and the seal 12Se can be suppressed.

  Further, when the exhaust brake is differential, the gas (mainly exhaust gas Ex) staying between the exhaust valve 5e and the valve body 12V of the exhaust brake valve 12 shown in FIG. 1 can be cooled by the cooling water flowing through the exhaust-side coolant passage. . Thereby, the temperature rise of the valve body 12V, the bearing 12B that supports the valve body 12V, and the seal 12Se that suppresses the leakage of exhaust gas can be suppressed, and a decrease in durability can be suppressed.

  At least one of the exhaust side cooling medium passage, that is, the first exhaust side cooling medium passage 31 and the second exhaust side cooling medium passage 32 may be disposed on the combustion space 1B side shown in FIG. preferable. In this way, since the exhaust gas Ex is cooled by the cooling water flowing through the exhaust side cooling medium passage and then passes through the valve body 12V, the temperature rise of the bearing 12B, the seal 12Se, and the valve body 12V can be more effectively suppressed. .

  Further, at least one of the exhaust side cooling medium passage, that is, at least one of the first exhaust side cooling medium passage 31 and the second exhaust side cooling medium passage 32, is at least the valve body 12V of the exhaust brake valve 12 serving as a gas flow rate adjusting means. It is preferable to surround a part. As a result, the bearing 12B that supports the valve body 12V and the seal 12Se that suppresses exhaust gas leakage can be cooled, so that the temperature rise of the bearing 12B and the seal 12Se can be more effectively suppressed.

  Further, since the valve body 12V of the exhaust brake valve 12 is arranged in the exhaust passage collecting portion 14 of the exhaust manifold 15 formed in the cylinder head 1H, the exhaust valve 5e shown in FIG. 1 to the valve body 12V of the exhaust brake valve 12 are arranged. The volume of can be reduced. As a result, the responsiveness when the valve body 12V is closed and the exhaust brake is operated is improved, and a decrease in the amount of internal EGR (Exhaust Gas Recirculation) can be suppressed. In addition, since the exhaust manifold 15 is formed in the cylinder head 1H, heat radiation from the exhaust manifold 15 to the atmosphere is extremely small, and the heat capacity of the exhaust passage is also small, further reducing the time required for warm-up. it can.

  Further, according to the configuration of the present embodiment, when the internal combustion engine 1 is warmed up, the first exhaust side cooling medium passage 31 and the second exhaust side disposed around the exhaust port 4 are closed by closing the valve body 12V. The heat of the exhaust gas Ex passing through the exhaust port 4 can be efficiently transmitted to the cooling water CF in the cooling medium passage 32, so that warm-up can be completed at an early stage. Next, a method for completing warm-up early by controlling the exhaust brake valve 12 during warm-up will be described.

  When warming up the internal combustion engine 1, the warm-up switch 56 attached to the engine ECU 50 is turned ON. Then, the exhaust brake actuator 12A constituting the exhaust brake valve 12 causes the valve body 12V constituting the exhaust brake valve 12 to open more than the opening when the exhaust brake is not operated after the warm-up of the internal combustion engine 1 is completed. Set to a small predetermined opening. In this way, before the warm-up of the internal combustion engine 1 is completed, the flow rate of the gas (in this case, the exhaust gas Ex) passing through the valve body 12V becomes smaller than after the warm-up of the internal combustion engine 1 is completed.

  As a result, the time during which the exhaust gas Ex stays in the exhaust port 4 and the exhaust passage collecting portion 14 can be lengthened. This can be efficiently transmitted to the cooling water CF flowing inside the exhaust side cooling medium passage 32. As a result, warming up of the internal combustion engine 1 can be completed early. Here, the opening when the exhaust brake is not operated after the warm-up of the internal combustion engine 1 is completed is, for example, fully open. Therefore, the opening degree of the valve body 12V before the warm-up of the internal combustion engine 1 is completed becomes a predetermined opening degree that is smaller than the fully open state.

  As shown in FIG. 2, the internal combustion engine 1 has an exhaust manifold 15 formed in the cylinder head 1H. In the present embodiment, the internal combustion engine 1 is disposed in the cylinder head 1H and around the exhaust port 4. A cooling medium passage (exhaust-side cooling medium passage) through which the cooling medium passes may be provided. For example, the internal combustion engine 1a shown in FIG. 5 includes an exhaust manifold 15a outside the cylinder head 1H, but the exhaust side in which the cooling water CF as a cooling medium passes around the exhaust port 4 in the cylinder head 1Ha. A cooling medium passage 33 is provided. Even in such a configuration, the exhaust gas Ex passing through the exhaust port 4 that constitutes the exhaust passage can be cooled by the cooling water CF, so that the temperature of the valve body 12V, the bearing 12B that supports the valve body 12V (see FIG. 3), and the like is increased. Can be suppressed, and a decrease in these durability can be suppressed.

  Further, since the exhaust gas Ex passing through the exhaust port 4 constituting the exhaust passage can be cooled by the cooling water CF, the valve body 12V and the like can be disposed closer to the exhaust outlet side of the internal combustion engine 1a. That is, the volume of the passage through which the exhaust gas Ex passes from the exhaust valve of the internal combustion engine 1a to the valve body 12V of the exhaust brake valve can be further reduced. As a result, the volume of the exhaust manifold 15a can be reduced, so that the responsiveness when closing the valve body 12V and operating the exhaust brake is improved.

  In addition, when the exhaust brake is operated, the amount of exhaust gas Ex remaining in the exhaust port 4, the exhaust manifold 15a, or the exhaust passage collecting portion 14a is reduced, so that the amount of heat transfer to the valve body 12V and the like is suppressed. Thereby, temperature rise of valve body 12V etc. can be controlled. Further, when the internal combustion engine 1a is warmed up, the valve body 12V is closed, so that the heat of the exhaust gas Ex passing through the exhaust port 4 is converted into the cooling water CF in the exhaust-side cooling medium passage 33 disposed around the exhaust port 4. Can be communicated efficiently to complete warm-up early.

  The internal combustion engine 1 shown in FIG. 1 may include a variable intake valve lift amount mechanism that can change the lift amount of the intake valve 5i. Since an internal combustion engine having such a mechanism can change the amount of air Air introduced into the combustion space 1B by changing the lift amount of the intake valve 5i, a configuration without a throttle valve is also conceivable. In this case, it is conceivable that the exhaust brake valve 12 is provided to exert the braking force when the accelerator is off, but this embodiment is also suitable when such a configuration is adopted.

  As described above, in the present embodiment, the exhaust side cooling medium passage is provided around the exhaust port provided in the cylinder head of the reciprocating internal combustion engine to cool the exhaust gas passing through the exhaust port, and the combustion gas more than the exhaust port. An exhaust brake valve device for changing the flow rate of the gas passing through the exhaust port is provided on the downstream side in the flow direction. As a result, the exhaust gas cooled by the cooling medium flowing through the exhaust side cooling medium passage passes through the exhaust brake valve device, so that the temperature rise of the valve body, the bearing, the seal, and the like, which are components of the exhaust brake valve device, can be suppressed. As a result, the exhaust brake valve can be arranged at a position closer to the combustion space. Further, when the internal combustion engine is operated at a high load and the temperature of the exhaust gas is high, the exhaust gas is cooled by the cooling medium, which is effective in suppressing deterioration of the catalyst that purifies the exhaust gas.

  As described above, the internal combustion engine according to the present invention is useful for an internal combustion engine including an exhaust brake, and particularly suitable for suppressing the temperature rise of a valve disposed in an exhaust gas passage for operating the exhaust brake. ing.

It is sectional drawing about one cylinder which shows the structure of the internal combustion engine which concerns on this embodiment. It is a mimetic diagram showing a cylinder head of an internal-combustion engine concerning this embodiment. FIG. 3 is a schematic view showing a configuration of an exhaust brake valve provided in the internal combustion engine according to the present embodiment, which is a view taken along the line XX in FIG. 2. It is a schematic diagram which shows the structure of the cooling system with which the internal combustion engine which concerns on this embodiment is provided. It is a schematic diagram which shows the other structural example of the internal combustion engine which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Internal combustion engine 1B Combustion space 1H, 1Ha Cylinder head 1s Cylinder 3 Intake port 4 Exhaust port 5i Intake valve 5e Exhaust valve 7 Piston 10 Cylinder block 11 Water jacket 12 Exhaust brake valve 12B Bearing 12A Exhaust brake actuator 12V Valve body 12S Valve body drive shaft 12Se seal 13 Port injection valve 14 Exhaust passage assembly 15, 15a Exhaust manifold 16 Crankcase 22 Radiator 26 Coolant recovery passage 27 Coolant supply passage 28 Cylinder block cooling passage 29 Coolant branch passage 30 Water pump 31 No. 1 1 Exhaust side cooling medium passage 32 Second exhaust side cooling medium passage 33 Exhaust side cooling medium passage 50 Engine ECU
51 Exhaust brake switch 56 Warm-up switch

Claims (6)

In an internal combustion engine in which a piston reciprocates in a cylinder,
A cylinder head attached to one end of the cylinder;
An exhaust passage which is provided in the cylinder head and which is provided in the cylinder and communicates with a combustion space in which a mixture of fuel and air burns and an outside of the cylinder head;
An exhaust-side coolant passage formed around the exhaust passage and passing through the exhaust passage for cooling the combustion gas after the air-fuel mixture burns;
A gas flow rate adjusting means that is disposed downstream of the exhaust passage in the flow direction of the combustion gas and changes the flow rate of the gas passing through the exhaust passage;
An internal combustion engine comprising: In an internal combustion engine in which a piston reciprocates in a cylinder,
A cylinder head attached to one end of the cylinder;
A plurality of exhaust passages provided in the cylinder head and communicating with the outside of the cylinder head and a combustion space provided in the cylinder and in which a mixture of fuel and air burns;
An exhaust passage assembly portion in which at least two of the exhaust passages connected to different combustion spaces among the plurality of exhaust passages gather in the cylinder head;
An exhaust-side cooling medium passage formed around the exhaust passages and passing through the exhaust passage for cooling the combustion gas after the air-fuel mixture burns;
A gas flow rate adjusting means that is disposed downstream of the exhaust passage in the flow direction of the combustion gas and changes the flow rate of the gas passing through the exhaust passage;
An internal combustion engine comprising:   3. The internal combustion engine according to claim 2, wherein all the exhaust passages gather in one exhaust passage gathering portion in the cylinder head.   The internal combustion engine according to claim 2 or 3, wherein the gas flow rate adjusting means is disposed in the exhaust passage assembly portion.   The internal combustion engine according to any one of claims 1 to 4, wherein the exhaust side cooling medium passage surrounds at least a part of the gas flow rate adjusting means.   The gas flow rate adjusting means makes the flow rate of the gas passing through the gas flow rate adjusting means smaller before the warming up of the internal combustion engine is completed before the warming up of the internal combustion engine is completed. The internal combustion engine according to any one of claims 1 to 5.

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