JP2007291916A - Cooling device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure cooling performance and reliability of an engine while improving fuel economy by efficiently reducing thermal load of the engine with a small cooling water quantity with devising a structure of water jackets in a cylinder block and a cylinder head. <P>SOLUTION: The water jackets 15 are provided in an intake side and an exhaust side of a cylinder bore 1a respectively in the cylinder block 1. Each water jacket 15 is divided into an upper part 15a and a lower part 15b by a partition wall 16 and a communication path 17 establishing communication between the lower part 15b of the water jacket in the intake side and the upper part 15a of the water jacket 15 in the exhaust side is provided between cylinder bores. Communication holes 21a, as cooling water channels making the upper part 15a communicate with the water jacket 21 of the cylinder head 2 are provided in an exhaust side valve bridge part 2d of the cylinder head 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine cooling apparatus.

  Conventionally, as a cooling device for cooling an engine, a cooling water flow passage called a water jacket is formed in each of a cylinder block and a cylinder head, and a water jacket (hereinafter referred to as a cylinder block water jacket) in the cylinder block is used. It is known to cool the cylinder block and the cylinder head from the inside by flowing cooling water to a water jacket in the cylinder head (hereinafter referred to as a cylinder head water jacket). In this case, the coolant flows through the water jacket of the cylinder head and cylinder block, receives heat from the cylinder head and cylinder block by heat exchange, and exchanges heat with the cabin heater for heating the radiator and the vehicle interior. The heat quantity of cooling water is released.

  Here, in general, the portion of the engine where the heat load is high is 2 between cylinder bores in the cylinder block (hereinafter also referred to as between the cylinder bores), around the exhaust port of the cylinder head, particularly in the case of a 4-valve engine. For example, a valve bridge portion positioned between two exhaust valve holes. In particular, since the latter has a high thermal load on the valve bridge portion on the exhaust side of the cylinder head, cooling water from the cylinder block to the cylinder head is disclosed, for example, as disclosed in Patent Document 1, in order to cool the valve bridge portion on the exhaust side. And a flow path is formed in the cylinder head to flow cooling water to the valve bridge portion. Thereby, a valve bridge part can be cooled directly and the thermal load of a cylinder head can be reduced.

The cooling water supplied to the cylinder block and the water jacket of the cylinder head is generally sent from a water pump that operates by engine rotation.
JP 2005-69095 A

  By the way, as described above, the water pump for sending the cooling water to the water jacket in the cylinder block and the cylinder head operates in conjunction with the engine rotation. become. For this reason, it has been considered to improve fuel consumption by reducing the load on the engine, such as reducing the capacity of the water pump or using an electric pump instead of a mechanical pump that operates by engine rotation.

  However, if the capacity of the water pump for supplying cooling water to the water jacket of the cylinder block and the cylinder head is reduced or the electric pump with a relatively small discharge amount is changed, the cylinder block Sufficient cooling water is not supplied to portions with high heat loads such as between the cylinder bores and the exhaust side valve bridge portion of the cylinder head, resulting in a high temperature and a decrease in reliability.

  The present invention has been made in view of the above points, and the object of the present invention is to devise the structure of the water jacket in the cylinder block and the cylinder head so that the engine heat load can be efficiently reduced even with a small amount of cooling water. By reducing it well, it is to ensure the cooling performance and reliability of the engine while improving the fuel efficiency.

  In order to achieve the above object, in the engine cooling apparatus according to the present invention, the cylinder block water jacket located on the exhaust side and the intake side of the cylinder block is divided into an upper part and a lower part, and the cylinder bores in the cylinder block are separated from each other. In addition, a communication passage is provided to communicate between the lower part of the intake side cylinder block water jacket and the upper part of the exhaust side cylinder block water jacket, and the cylinder head is connected to the exhaust valve hole from the upper part of the exhaust side cylinder block water jacket. A cooling water flow path for cooling water to flow through the valve bridge was provided.

  Specifically, the invention of claim 1 is directed to a cylinder block water for cooling around the cylinder liner of the cylinder block of a water jacket provided in each of a cylinder head and a cylinder block forming a plurality of cylinders. An engine cooling apparatus having a jacket having a divided structure composed of an upper part and a lower part is an object.

  The cylinder block water jacket is provided on each of an intake side and an exhaust side of a cylinder bore constituting a part of the cylinder in the cylinder block, and between the cylinder bores in the cylinder block, the intake side A communication passage is provided for communicating the lower part of the water jacket with the upper part of the water jacket on the exhaust side, and cooling water is supplied to the cylinder head from the upper part of the water jacket on the exhaust side to the valve bridge portion between the exhaust valve holes. It is assumed that a cooling water flow path for flowing is provided.

  With this configuration, the cylinder block water jacket provided on the intake side and the exhaust side of the cylinder bore in the cylinder block is divided into an upper part and a lower part, and the lower part of the cylinder block water jacket on the intake side and the cylinder block water jacket on the exhaust side are divided. Since the upper part of the cylinder is communicated by a communication path, the cooling water can flow from the lower part of the intake side cylinder block water jacket to the upper part of the exhaust side cylinder block water jacket via the communication path, and the heat load is high. The exhaust side can be reliably cooled from the inside.

  The cylinder head is formed with a cooling water passage for flowing cooling water from the upper part of the water jacket on the exhaust side to the valve bridge portion. By this cooling water passage, the cooling water in the exhaust side water jacket is formed. Can flow through the valve bridge portion of the cylinder head having the highest thermal load, and the thermal load of the engine can be efficiently reduced.

  Further, since the communication path is provided between the cylinder bores constituting the cylinder in the cylinder block, the cylinder block efficiently cools between the cylinder bores having a relatively high heat load by the cooling water flowing through the communication path. Can do.

  Therefore, with the configuration as described above, even between a small amount of cooling water, it is possible to efficiently cool the cylinder block exhaust side, the valve bridge portion of the cylinder head, and the cylinder bore of the cylinder block with a relatively high heat load. The heat load can be efficiently reduced when the engine temperature is high, while suppressing the amount of heat released during cold by the low flow rate.

  In addition, with the configuration as described above, the amount of cooling water can be reduced without greatly degrading the cooling performance of the entire engine, so the capacity of the water pump can be reduced, and fuel consumption can be reduced. Can be improved. As a result, the water pump is not a mechanical pump that is driven by engine rotation, but can be an electric pump that has a relatively small discharge amount but does not place a heavy load on the engine, thereby further improving fuel efficiency. .

  In the above-described configuration, the lower portion of the cylinder block water jacket is preferably wider than the upper portion (the invention of claim 2). As a result, the flow resistance of the cooling water in the lower part of the cylinder block water jacket can be reduced, so that the resistance of the entire flow path of the cooling water can be reduced, the water pump can be further reduced in size, and the fuel consumption is further improved. Can be improved. Moreover, since the width of the upper part of the cylinder block water jacket is narrower than that of the lower part, the flow rate of the cooling water flowing in the upper part can be increased. The upper periphery of the exhaust side water jacket into which cooling water flows from the lower part of the jacket can be effectively cooled.

  Further, between the cylinder bores in the cylinder block, there is provided a communication hole for communicating the upper part and the lower part in the water jacket on the intake side and the exhaust side, respectively (invention of claim 3). Thus, by providing a communication hole that connects the upper and lower portions of the water jacket between the cylinder bores of the cylinder block, the cooling water flowing through the communication hole allows the cylinder block with the highest thermal load to pass between the cylinder bores. Cooling can be performed efficiently, and the engine heat load can be reduced.

  Furthermore, it is preferable that the lower part of the cylinder block water jacket is wider at the part closer to the water pump for sending the cooling water into the water jacket than at the part farther away (invention of claim 4). As a result, the flow resistance in the water jacket when the cooling water is sent from the water pump to the cylinder block water jacket can be reduced. Cooling water can be efficiently flowed into the jacket, and the cylinder head and the cylinder block can be cooled from the inside.

  According to the present invention, the cylinder block water jacket provided on the intake side and the exhaust side of the cylinder bore in the cylinder block is divided into upper and lower parts, and the lower part of the intake side cylinder block water jacket and the exhaust are disposed between the cylinder bores in the cylinder block. Since a communication passage that communicates with the upper cylinder block water jacket is provided, cooling water flows through the communication passage from the intake side to the exhaust side to efficiently cool between the cylinder bores having a relatively high heat load. It becomes possible to flow a lot of cooling water. And, by providing a cooling water flow path in the cylinder head for flowing the cooling water from the upper part of the cylinder water jacket on the exhaust side to the valve bridge part, the valve bridge part with the highest heat load can be efficiently cooled by the cooling water. Can do. As a result, even with a small amount of cooling water, it is possible to preferentially cool the portion with high heat load and effectively reduce the heat load of the entire engine, so that less discharge is ensured while ensuring the reliability and cooling performance of the engine. Fuel consumption can be improved by using an amount of pump. Moreover, since the amount of cooling water can be reduced by adopting the above-described configuration, it is possible to efficiently reduce the heat load at the time of high engine temperature while suppressing the amount of heat released during cold.

  Also, by providing a communication hole between the cylinder bores that allows the upper and lower parts of the cylinder block water jacket to communicate with each other, it is possible to effectively cool between the cylinder bores with the highest heat load in the cylinder block, and the engine can be used even with a small amount of cooling water. The heat load can be reduced more efficiently.

  Furthermore, by making the width of the lower part of the cylinder block water jacket wider than the upper part, or making the width of the lower part close to the water pump wider than the far part, the overall flow resistance can be reduced, Fuel consumption can be further improved by downsizing or electrification of the pump.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

  FIG. 1 is a schematic perspective view of an entire engine E according to an embodiment of the present invention, FIG. 2 is a top view of a cylinder block 1, and FIGS. 3a, 3b, and 4 show the engine E in FIG. Sectional drawing at the time of cutting | disconnecting by the IIIa-IIIa line | wire, IIIb-IIIb line | wire, and IV-IV line | wire in FIG.

  In this embodiment, the engine E is an in-line four-cylinder engine in which four cylinders 11, 11,... Are arranged in series along the axial direction of the crankshaft (not shown) (the left-right direction in FIG. 1). It is. The engine E is composed of an aluminum alloy cylinder block 1 and a cylinder head 2 made of the same aluminum alloy that is assembled to the upper side of the cylinder block 1. The engine E is formed by the cylinder block 1 and the cylinder head 2. In the cylinders 11, 11,..., Pistons (not shown) are configured to move up and down. In FIG. 1, a cylinder head cover 30 is attached above the cylinder head 2.

  The engine E is mounted horizontally in an engine room provided at the front of the vehicle so that the crankshaft extends in the vehicle width direction. As shown in FIG. 1, an intake manifold 40 for introducing intake air into each cylinder 11 is disposed. The intake manifold 40 has four branch pipes, and each branch pipe communicates with each cylinder 11 in the engine E, although not particularly shown. On the other hand, an exhaust system (exhaust manifold, etc., not shown) is provided on the right side of the engine E (the back side in FIG. 1).

  Further, on the left front side of the engine E (the front left side in FIG. 1), cooling water is sent into water jackets 15 and 21 formed in the cylinder block 1 and the cylinder head 2 as will be described later. A water pump 7 is provided. The water pump 7 is driven by a crankshaft (not shown) via a crank pulley 50 provided on the engine front side of the cylinder block 1.

  As shown in FIG. 2, the cylinder block 1 has cylinder bores 1a, 1a,... Constituting a part of the plurality of cylinders 11, 11,. The cylinder bores 1a, 1a, 1a, 1a, 1a, 1b, 2c are formed so as to cool the periphery of the cylinder liner 12 disposed on the inner peripheral surface of each cylinder 11 (on the inner peripheral surface of the cylinder bore 1a). Cavities 15 and 15 (cylinder block water jackets, hereinafter also referred to as water jackets) are formed on the intake side and the exhaust side of... (See FIGS. 3 to 6).

  Further, in the cylinder block 1, bolt holes 1 b into which bolts for fastening bolts to the cylinder head 2 are screwed on both ends in the cylinder row direction (cylinder row direction) and between the cylinder bores, respectively. , 1b,... Are formed. Further, the gas leaked from the combustion chamber to the crank chamber in the compression / combustion stroke of the engine E at positions outside the bolt holes 1b, 1b,. Are provided for returning the air to the intake system.

  The water jackets 15 and 15 are flow passages for flowing cooling water to the intake side and the exhaust side inside the cylinder block along the side surfaces of the cylinder bores 1a, 1a,... As shown in FIGS. The upper surface of the cylinder block 1 is formed in a groove shape that opens upward. Each of the water jackets 15 is provided with a partition wall 16 for partitioning the water jacket 15 into two upper and lower spaces (see FIGS. 3a and 3b). That is, the partition wall 16 is provided so as to extend inside the water jackets 15 in the cylinder row direction, whereby the water jacket 15 is divided into an upper part 15a and a lower part 15b.

  As shown in FIGS. 2 and 4, the upper portion 15 a and the lower portion 15 b of the water jacket 15 are arranged at one end side (engine rear side) of each cylinder bore 1 a in the cylinder row direction (cylinder row direction) in the cylinder block 1. Are connected to each other through block communication holes 15c, 15c,..., And are discharged from the water pump 7 provided on the front side of the engine to the rear side of the engine as shown in FIGS. Is divided into an intake side and an exhaust side on the engine front side of the cylinder block and flows into the lower portion 15b, and then flows into the upper portion 15a through the block communication holes 15c, 15c,. 4 to 6). That is, in the upper portion 15a, as shown in FIG. 2, the cooling water flows in parallel around the cylinders from the lower portion 15b through the block communication holes 15c, 15c,. Therefore, the flow rate of the cooling water when passing through the block communication holes 15c, 15c,... Can be made uniform, and the cylinder bores with the highest heat load in the cylinder block 1 can be efficiently cooled.

  Here, as shown in FIGS. 3a, 3b, and 4, the water jacket 15 is partitioned by the partition wall 16 so that the lower portion 15b is larger in height than the upper portion 15a. The width dimension of 15b is formed to be larger than that of the upper part 15a. In this way, the width of the lower portion 15b is made wider than the upper portion 15a of the water jacket 15, thereby reducing the flow resistance of the cooling water in the lower portion 15b, and the cooling water flowing in the upper portion 15a having a narrower width than the lower portion 15b. The flow rate can be made faster than the cooling water flow rate in the lower part 15b.

  Therefore, with the above-described configuration, it is possible to supply cooling water having a high flow rate to the water jacket 21 of the cylinder head 2 communicating with the upper portion 15a as described later while reducing the flow resistance of the entire cooling water flow path. Therefore, the water pump 7 for discharging the cooling water can be made smaller, and the upper part of the cylinder block 1 and the cylinder head 2 can be efficiently cooled from the inside even if the amount of the cooling water is small.

  As shown in FIGS. 2 and 4, the cylinder block 1 includes a lower portion 15b of the intake-side water jacket 15 and an upper portion of the exhaust-side water jacket 15 in the intake-side and exhaust-side water jackets 15 and 15. A communication passage 17 called a cross drill that communicates with 15a is provided between the cylinder bores. By providing the communication passage 17, the cooling water is supplied to the upper portion 15a of the water jacket 15 on the exhaust side not only from the lower portion 15b but also from the lower portion 15b of the water jacket 15 on the intake side.

  As a result, more cooling water flows into the upper portion 15a of the water jacket 15 on the exhaust side, so that not only the exhaust side of the cylinder block 1 having a relatively high heat load but also a high heat load as will be described later. The cylinder head 2 on the exhaust side can be cooled more effectively. Further, by providing the communication passage 17 between the cylinder bores of the cylinder block 1, the cylinder bore having the highest temperature in the cylinder block 1 can be cooled by the cooling water flowing in the communication passage 17, and the entire engine E can be cooled. The heat load can be reduced efficiently.

  As shown in FIGS. 5 and 6, the lower portion 15b of the water jacket 15 extends in the cylinder row direction of the cylinder block 1 to form one large space on the exhaust side and the intake side of the cylinder bores 1a, 1a,. On the other hand, the upper portion 15a is partitioned corresponding to each cylinder bore 1a, as shown in FIG. That is, the upper portion 15a of the water jacket 15 is provided between the cylinder bores of the cylinder block 1 so that the exhaust side and intake side flow passages 15d, 15e,... Are formed independently for each cylinder bore 1a, 1a,. It is partitioned off by the provided partition walls 1d, 1d,.

  As shown in FIG. 1, in the present embodiment, the exhaust side and the intake side are configured by one flow path at both ends in the cylinder row direction of the upper portion 15a of the water jacket 15, but this is not restrictive. The exhaust side and intake side of the upper portion 15a may be partitioned by the partition wall 1d at both ends in the cylinder row direction.

  As described above, the intake side flow passages 15d, 15d,... And the exhaust side flow passages 15e, 15e,... Are formed in the upper portion 15a of the water jacket 15 in the cylinder block 1 for each cylinder bore 1a. The intake side flow passages 15d and the exhaust side flow passages 15e are respectively formed with the block communication holes 15c for communicating the upper portion 15a and the lower portion 15b of the water jacket 15 (both ends in the cylinder row direction). Since the intake side flow passage 15d and the exhaust side flow passage 15e are connected to form a single flow path at the end portion on the rear side of the engine, one block communication hole 15c). , 15e,..., 15e,... Do not merge, and the flow rate of the cooling water does not decrease due to the merge, so that the upper part of the cylinder block 1 and the cylinder head 2 can be efficiently cooled.

  Here, as a method of manufacturing the cylinder block 1 having the water jacket 15 divided into two upper and lower spaces as described above, two casting methods of low pressure casting or die casting are conceivable. In the former low pressure casting, since the molten metal is poured into the mold at a low pressure, a core can be used, and the upper portion 15a of the water jacket 15 of the cylinder block 1 is formed by the upper die for forming the cylinder block 1. On the other hand, the lower part 15b is formed by a core. In the case of this low pressure casting, in order to support the above-mentioned core, baseboards are provided at the side (engine side) and front and rear (engine front side, rear side) positions of the cylinder block 1. Thereby, the cylinder block 1 having the water jacket 15 partitioned into two upper and lower spaces can be easily manufactured integrally.

  On the other hand, the latter die casting is a method in which molten metal is press-fitted into a precise mold at a high pressure, and the lower portion 15b of the water jacket 15 cannot be formed using a core as in the low-pressure casting described above. As shown, groove portions 1e and 1e extending in the cylinder row direction (engine longitudinal direction) are integrally formed on the left and right side surfaces (left and right sides in FIG. 8) of the cylinder block 1, respectively. The lower part 15b is formed by covering 1e with covers 13 and 13 which are bolted to the side of the cylinder block 1. In this way, when casting is performed by die casting, the cylinder block 1 can be produced in large quantities using a mold, so that the productivity of the cylinder block 1 can be improved.

  The cylinder head 2 is a member made of an aluminum alloy that is attached to the upper side of the cylinder block 1, and a space constituting a part of the combustion chamber 3 is formed on the lower surface, and the combustion chamber 3, the intake pipe and the exhaust pipe are provided inside. Arrangement space for an intake port 4 and an exhaust port 5 (see FIGS. 5 and 6) that communicate with (not shown) and a spark plug 6 (see FIGS. 3a and 3b) for igniting the gas in the combustion chamber 3 Etc. are provided.

  Further, inside the cylinder head 2, as shown in FIGS. 3 a, 3 b, 5, and 6, there is a cavity as a cooling water flow path for cooling the periphery of the intake port 4 and the exhaust port 5. 21 (cylinder head water jacket, hereinafter also referred to as a water jacket) is formed. Further, the cylinder head 2 is formed with a plurality of communication holes 21a, 21a,... So that the water jacket 21 communicates with an upper portion 15a of the water jacket 15 formed in the cylinder block 1.

  Specifically, these communication holes 21a, 21a,... Are formed on the intake side of each cylinder bore 1a in the top view as shown in FIG. 2 with respect to the upper portion 15a of the water jacket 15 of the cylinder block 1. The block communication hole 15c is formed at the end of the cylinder bore 1a opposite to the cylinder row direction, and on the exhaust side of each cylinder bore 1a, it is formed near the center of the cylinder bore in the cylinder row direction. As shown in FIG. 2, the communication hole 21a is also provided on the other end side (the engine front side) in the cylinder row direction in addition to the above, and is on the intake side of the cylinder bore 1a located on the engine front side. In addition, among the cooling water that has flowed through the exhaust side, the remaining cooling water that has not flowed to the cylinder head 2 side through the communication holes 21a, 21a,. It is configured.

  As a result, the cooling water flowing in the upper portion 15a of the water jacket 15 of the cylinder block 1 flows in the entire circumferential direction along the intake side portion of each cylinder bore 1a on the intake side of each cylinder bore 1a. On the exhaust side of the cylinder head 2, the exhaust gas flows along the exhaust side portion of each cylinder bore 1 a in the circumferential direction about half of the portion and flows into the water jacket 21 of the cylinder head 2.

  Therefore, by adopting the above-described configuration, the intake side of the cylinder block 1 is sufficiently cooled by the cooling water, so that abnormal combustion can be prevented from occurring on the intake side where the flame propagation is slow in the combustion chamber. The occurrence of knocking can be suppressed.

  Further, with the above-described configuration, the exhaust side of the cylinder block 1 has a shorter distance through which the coolant flows through the upper portion 15a than the intake side, and the coolant is supplied to the cylinder head 2 side earlier than the intake side. The cylinder head 2 can be effectively cooled from the inside.

  Here, the engine E is a four-valve engine in which two intake valves and two exhaust valves (not shown) are provided for the intake port 4 and the exhaust port 5 of one cylinder, as shown in FIG. The cylinder head 2 is formed with two valve holes 2a, 2a, 2b, 2b on the intake side and the exhaust side of one cylinder.

  Therefore, portions between the valve holes 2a, 2a, 2b, 2b, that is, valve bridge portions 2c, 2d are formed on the intake side and the exhaust side of the cylinder head 2. These valve bridge portions 2c and 2d are likely to become high temperature due to the heat of the ports 4 and 5, and particularly on the exhaust side through which high-temperature gas flows, the heat load on the valve bridge portion 2d is the highest. It is necessary to sufficiently cool the valve bridge portion 2d.

  .. Of the water jacket 21 is provided in the valve bridge portion 2d with a communication hole 21a (cooling water flow path) located on the exhaust side of each cylinder. Cooling water is directly supplied from the upper portion 15a to the valve bridge portion 2d having the highest heat load. That is, inside the valve bridge portion 2d of the cylinder head 2, as described above, the cooling water that has flowed to the half of the circumferential direction on the exhaust side of each cylinder in the upper portion 15a of the water jacket 15 of the cylinder block 1 is provided. As a result, the valve bridge portion 2d can be preferentially cooled, and the engine can be cooled efficiently. In FIG. 7, reference numeral 2e denotes a plug boss portion where the spark plug 6 is disposed.

  Here, as shown in FIGS. 3 a, 3 b and 4, a metal gasket 8 is sandwiched between the cylinder block 1 and the cylinder head 2. As a matter of course, the gasket 8 also has communication holes 21a, 21a,... For connecting the water jacket 21 of the cylinder head 2 to the upper portion 15a of the water jacket 15 of the cylinder block 1 and bolt holes 1b, 1b, ..., through holes are formed corresponding to the blow-by passages 1c, 1c,.

  With the above configuration, the water jackets 15, 15 formed on the cylinder bore intake side and the exhaust side in the cylinder block 1 are partitioned into two upper and lower spaces by the partition walls 16, 16, and the lower part of the water jacket 15 on the intake side 15b and the upper portion 15a of the water jacket 15 on the exhaust side communicate with each other through a communication passage 17 provided between the cylinder bores, so that a large amount of cooling water can flow through the upper portion 15a of the water jacket 15 on the exhaust side. The exhaust side with a high dynamic heat load can be effectively cooled. In addition, since the communication path 17 is provided between the cylinder bores of the cylinder block 1, it is possible to efficiently cool between the cylinder bores having the highest heat load in the cylinder block 1 to reduce the heat load of the entire engine.

  Further, the upper portion 15a of the water jacket 15 in the cylinder block 1 and the water jacket 21 in the cylinder head 2 are configured to communicate with each other through communication holes 21a, 21a,... Since the cylinder head 2 is provided in the portion between the exhaust valve holes 2b and 2b having the highest heat load, that is, the valve bridge portion 2d, the coolant collected in the exhaust side as described above is caused to flow into the communication hole 21a. By flowing in, the valve bridge portion 2d on the exhaust side can be effectively cooled from the inside, and the thermal load of the engine can be efficiently reduced.

  In particular, in the above-described embodiment, the communication holes 21a, 21a,... Are arranged on the intake side of the cylinder bore 1a in the cylinder row of the cylinder bore 1a with respect to the communication holes 15c communicating the upper portion 15a and the lower portion 15b of the water jacket 15. On the other hand, on the exhaust side of the cylinder bore 1a, it is provided near the center of the cylinder bore in the cylinder row direction. Therefore, on the intake side, cooling water flows around each cylinder bore 1a of the cylinder block 1 for comparison. On the exhaust side where the target temperature is high, the cooling water is supplied to the cylinder head 2 earlier than the intake side. As a result, the cylinder block 1 can be sufficiently cooled on the intake side of each cylinder bore 1a to suppress the occurrence of knocking. On the exhaust side, a large amount of cooling water is allowed to flow through the cylinder head 2 early. 2 can be effectively cooled.

  Further, the upper and lower portions 15a and 15a and the lower portions 15b and 15b of the water jackets 15 and 15 on the intake side and the exhaust side in the cylinder block 1 have block communication holes 15c and 15c formed between the cylinder bores in addition to the communication path 17. The cooling water flows from the lower part 15b to the upper part 15a through the communication holes 15c, 15c, ..., so that the entire cylinder block 1 and the cylinder head 2 can be cooled from the inside. In addition, since the block communication holes 15c, 15c,... Are provided between the cylinder bores that become relatively high in temperature, the space between the cylinder bores can be cooled with cooling water. Further, since the cooling water flows from the lower portion 15b to the upper portion 15a around the bore 1a via the block communication holes 15c, 15c,... For each cylinder bore 1a, the block communication holes 15c, 15c,. The flow rate of the cooling water when passing through can be made uniform, and the space between the cylinder bores can be reliably cooled.

  In this way, by configuring the cooling water to flow preferentially to a portion having a relatively high heat load, even when the amount of cooling water is small, the portion having a high heat load can be preferentially cooled. It is possible to achieve both improvement in fuel efficiency by reducing the capacity of the pump 7 or electrification and ensuring reliability by preventing deterioration of the cooling performance of the engine E.

  Further, since the lower portion 15b of the water jacket 15 of the cylinder block 1 is formed to be wider than the upper portion 15a, the flow resistance of the cooling water in the lower portion 15b can be reduced, and the comparison is made. The flow rate of the cooling water in the upper portion 15a having a narrow target width can be increased, and the inside of the cylinder head 2 communicating with the upper portion 15a can be effectively cooled. Further, in the lower portion 15b, the width Wf (see FIG. 3a) on the side closer to the water pump 7 (see the vicinity of the front cylinder) is wider than the width Wr (see FIG. 3b) on the far side (in the vicinity of the rear cylinder). The flow resistance of the cooling water in the lower part 15b can also be reduced by forming it as described above. Thus, by reducing the flow resistance of the cooling water in the water jacket 15, the flow resistance of the entire flow path of the cooling water can be reduced, thereby further reducing the capacity of the water pump 7. Engine load can be reduced, and fuel consumption can be further improved.

(Other embodiments)
The configuration of the present invention is not limited to the above embodiment, but includes various other configurations. That is, in the above embodiment, the exhaust holes 21a, 21a,... Formed in the cylinder head 2 so as to communicate the upper portion 15a of the water jacket 15 of the cylinder block 1 and the water jacket 21 of the cylinder head 2 are exhausted. Are arranged near the center of the cylinder bore in the cylinder row direction (see FIG. 2). However, the present invention is not limited to this, The cylinder bore 1a may be provided on the opposite side of the cylinder bore 1a in the cylinder row direction with respect to the block communication holes 15c, 15c,... Communicating with the upper portion 15a and the lower portion 15b of the cylinder block water jacket 15.

  In the above embodiment, the present invention is applied to an in-line four-cylinder engine in which four cylinders are arranged in series. However, the present invention is not limited to this. For example, an engine having a larger number of cylinders than four cylinders, such as six cylinders and eight cylinders. You may apply.

  As described above, the engine cooling apparatus according to the present invention divides the water jacket located on the intake side and the exhaust side of the cylinder block into upper and lower parts, and the lower part of the intake side water jacket and the upper part of the exhaust side water jacket. By providing a communication passage that communicates with the cylinder bore, the exhaust side with a high heat load can be efficiently cooled even with a small amount of cooling water, and it is possible to achieve both improvement in fuel efficiency and ensuring engine reliability. For example, it is particularly useful for an engine that operates with low fuel consumption.

1 is a perspective view showing a schematic configuration of an engine according to an embodiment of the present invention. It is a top view of a cylinder block. It is the IIIa-IIIa sectional view taken on the line in FIG. It is the IIIb-IIIb sectional view taken on the line in FIG. It is the IV-IV sectional view taken on the line in FIG. FIG. 2 is a partial cross-sectional view taken along the line Va-Va in FIG. 1 (only the cylinder block, and the cylinder head is a cross-sectional view taken along the line Vb-Vb). FIG. 2 is a partial cross-sectional view taken along line VIa-VIa in FIG. 1 (only the cylinder block, and the cylinder head is a cross-sectional view taken along line VIb-VIb). It is the VII-VII line sectional view in Drawing 3a (Drawing 3b). It is a figure equivalent to Drawing 3a (Drawing 3b) at the time of manufacturing a cylinder block by die casting.

Explanation of symbols

E Engine 1 Cylinder block 1a Cylinder bore 1d Partition wall 2 Cylinder head 2a Intake side valve hole 2b Exhaust side valve hole (exhaust valve hole)
2c Intake side valve bridge 2d Exhaust side valve bridge (valve bridge)
7 Water pump 11 cylinder (cylinder)
12 Cylinder liner 15 Cavity (Cylinder block water jacket)
15a Upper part 15b Lower part 15c Block communication hole 17 Communication path 21 Hollow part (cylinder head water jacket)
21a Communication hole (cooling water flow path)

Claims (4)

Of the water jackets provided inside the cylinder head and the cylinder block that form a plurality of cylinders, the cylinder block water jacket for cooling around the cylinder liner of the cylinder block is divided into an upper part and a lower part. An engine cooling device,
The cylinder block water jacket is provided on each of an intake side and an exhaust side of a cylinder bore constituting a part of the cylinder in the cylinder block,
Between the cylinder bores in the cylinder block, a communication passage is provided for communicating the lower part of the water jacket on the intake side with the upper part of the water jacket on the exhaust side,
The engine cooling apparatus according to claim 1, wherein the cylinder head is provided with a cooling water passage for flowing cooling water from an upper portion of the water jacket on the exhaust side to a valve bridge portion between the exhaust valve holes. In claim 1,
An engine cooling apparatus characterized in that the lower part of the cylinder block water jacket is wider than the upper part. In any one of Claim 1 or 2,
A cooling device for an engine, characterized in that communication holes are provided between the cylinder bores in the cylinder block so as to communicate the upper part and the lower part of the cylinder block water jacket on the intake side and the exhaust side, respectively. In any one of Claims 1-3,
The engine cooling apparatus according to claim 1, wherein a lower portion of the cylinder block water jacket is wider at a portion closer to a water pump for sending cooling water into the water jacket than at a far portion.

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