JP2021008836A - Internal combustion engine - Google Patents

Abstract

To prevent the local ebullition (a local abnormal temperature rise of a cylinder block) of cooling water without impairing a warmup promotion effect, in a two-system cooling type internal combustion engine which does not make the cooling water flow to a block jacket at a warmup operation.SOLUTION: Water is made to slightly flow to block jackets 6 (65, 66) at a warmup operation via a leak passage. A drill passage 69 for making cooling water flow to a head jacket 7 from a constricted part 66a of a block jacket intake-side portion 66 is opened at an inter-bore part 68. Also, the block jacket intake-side portion 66 and the head jacket 7 communicate with each other via a small-diameter ventilation hole 74. By a negative pressure effect of the head jacket 7, the cooling water can be made to flow to the head jacket 7 from the drill passage 69 and the ventilation hole 74.SELECTED DRAWING: Figure 7

Description

The present invention relates to an internal combustion engine characterized by controlling the flow of cooling water.

In an internal combustion engine for automobiles and the like, the cylinder block and the cylinder head are cooled by cooling water. That is, the cylinder block is formed with a cooling water passage (block jacket) surrounding a group of cylinder bores, while the cylinder head is formed with a cooling water passage (head jacket) having a planar spread, and the water pump. The cooling water pumped by the engine is sent to the block jacket and head jacket.

Since the cylinder head is hotter than the cylinder block, the cooling water does not flow through the block jacket during warm-up operation, but only through the head jacket, and when the warm-up operation is removed, the cooling water also flows through the block jacket. A system has been proposed, and this two-system cooling test has advantages such as being able to prevent the cylinder block from being overcooled and being able to raise the temperature of the cooling water at an early stage to shorten the warm-up operation time.

However, even during warm-up operation, a local high temperature part (hereinafter referred to as heat spot) is generated in the upper part of the block (combustion chamber side) due to overload such as sudden start or uphill running, and the cooling water of the block jacket is locally generated. When such a phenomenon of sudden boiling of cooling water occurs, the temperature of the cylinder block member becomes abnormally high locally due to the heat insulation of the generated part by steam, and the allowable heat resistance of the member occurs. It may exceed the temperature or cause knocking.

Therefore, if a heat spot is generated on the upper side of the cylinder block during warm-up operation, it is considered to eliminate the heat spot. As an example, in Patent Document 1, an abnormal combustion detecting means is provided in the engine to detect abnormal combustion. It is disclosed that when the detection is detected, the valve is opened to form a flow of cooling water in the block jacket. On the other hand, in Patent Document 2, a jiggle pin (pressure regulating valve) that opens and operates when a predetermined pressure is reached is provided in the communication portion between the block jacket and the head jacket, and when the cooling water becomes high in temperature and boils, the jiggle pin opens to supply the cooling water. It is disclosed that the block jacket escapes to the head jacket.

Japanese Unexamined Patent Publication No. 62-099615 Japanese Unexamined Patent Publication No. 05-256131

Both Patent Documents 1 and 2 have a problem that the structure is complicated and the cost is increased because it is necessary to arrange a dedicated valve in order to eliminate the heat spot. Further, it is intended to eliminate the heat spot after it is generated, and it can be said that the function of preventing (preventing) the generation of the heat spot is not necessarily high.

Further, when examined individually, first, in Patent Document 1, the operation of the valve is related to the abnormal combustion of the engine, but in the two-system cooling system, the cooling water stays in the block jacket during the warm-up operation. Therefore, even if the engine is not abnormally burned, local high temperature (heat spotting) may occur, and there is a problem that it is not possible to cope with such partial high temperature under normal combustion. ..

On the other hand, looking at Patent Document 2, the jiggle pin is a kind of pressure regulating valve, and the cooling water that has become hot due to the valve body moving against the spring escapes to the head jacket, but the cooling water is required to open the jiggle pin. Since it must be boiled, it is doubtful whether the abnormally heated cooling water can be quickly released to properly cool the cylinder block. Further, since the heat spot does not always occur at the location where the jiggle pin is arranged, it can be said that there is a problem in the certainty of the response.

The present invention has been made in the wake of such a situation, and the warm-up promotion effect is to prevent a heat spot from being generated in the cylinder block during warm-up operation and further raising the member temperature from local boiling. It is intended to be realized by a simple structure without damaging the above.

The internal combustion engine of the present invention is
"A head jacket formed on the cylinder head to cool the cylinder head, a block jacket formed on the cylinder block to cool the cylinder block, and cooling water pumped from a water pump are applied to the head jacket. It has a water supply passage to the head to send and a water passage to the block to send the cooling water pumped from the water pump to the block jacket.
While a valve that controls water flow according to the temperature of the cooling water is arranged in the water supply passage to the block,
The block jacket is a block jacket exhaust side portion located on the exhaust side across a group of cylinder bores, a block jacket intake side portion located on the intake side across the cylinder bore group, and a block jacket side portion that communicates both. The block jacket exhaust side portion and the block jacket intake side portion have a constricted portion that has entered toward the space between the bores. "
It has a basic structure.

And in the above basic configuration
"The head jacket allows cooling water to flow from a leak passage that allows a small amount of cooling water to flow through the block jacket even when the valve is closed, and a constricted portion on the intake side portion of the block jacket or a constricted portion on the exhaust side portion of the block jacket. There is a constriction cooling means that flows toward
The configuration is added.

In the present invention, the leak passage can be easily formed by, for example, making a communication hole in the valve seat plate of the valve, or communicating the head passage and the block jacket with a groove or a hole.

Further, in order to cool the inter-bore portion of the cylinder block, it has been conventionally practiced to make a drilled passage (drilled hole) in the inter-bore portion, and further, it is inserted between the cylinder block and the cylinder head. Air vent holes are also provided in the gasket,
As the constriction cooling means, either one or both of the drilled passage and the air vent hole can be used.

In a multi-cylinder internal combustion engine, the temperature of the upper part (constricted portion on the combustion chamber side) between the bores sandwiched between adjacent cylinder bores becomes high. In addition, since the space between the bores of the block jacket is constricted, it tends to stagnate, and when the engine has a slant angle, the upper part of the constriction becomes an air pool, so the upper part between the bores of the cylinder block (on the combustion chamber side). The constricted part) becomes a heat spot, and local boiling of the cooling water (sudden boiling phenomenon) is likely to occur, and there is a concern that the allowable heat resistant temperature of the member may be exceeded due to a further rise in the member temperature, or knocking may occur.

Then, in the present invention, the existing drilled passage for cooling the upper part (necked portion) between the bores of the block jacket, which becomes locally hot, and the air vent hole provided in the head gasket are used to make the block jacket. Even during warm-up, which shuts off the flow of cooling water, a small amount of cooling water flows into the block jacket to cause cooling water to flow from the drilled passage or air vent hole toward the head jacket, causing the cooling water to stay in the constriction. It is possible to prevent the abnormal rise (heat spotting) of the member temperature of the constricted part and prevent (prevent) the local boiling of the cooling water (in the constricted part, the cooling water receives more heat than other parts. Since the temperature tends to rise and convection is likely to occur, it can be said that a flow of water is easily formed in the block jacket by flowing a small amount of cooling water through the block jacket.)

Therefore, it is possible to prevent the member temperature from abnormally rising due to the local boiling of the cooling water starting from the heat spot between the bores of the cylinder block, and to prevent the member from exceeding the allowable heat resistant temperature and knocking. The roundness of the cylinder bore can be maintained to prevent the increase of blow-by gas. In this respect, it is a great advantage that cannot be enjoyed by the technology corresponding to the occurrence of heat spots as in Patent Documents 1 and 2.

The amount of leaked water to the block jacket may be limited to a portion that becomes a heat spot when the cooling water flow is cut off so that the accumulated cooling water can be flowed. Therefore, a small amount is sufficient, so that the cylinder is used during warm-up operation. The block is not overcooled and the effect of early warm-up is not lost, and no moving members are required and the structure is simple. Therefore, it is possible to realize early warm-up while preventing the local abnormal temperature rise of the cylinder block with a simple structure.

It is a figure which shows the embodiment, (A) is a schematic view which shows the cooling system, (B) is IB-IB sectional view of FIG. (A) is a plan view, and (B) is a partial plan view showing another example of the leak passage. It is a side view which separated the water pump from a cylinder block. It is an IV-IV sectional view of FIG. 2 (A) and FIG. 5 (A). (A) is a sectional view taken along line VA-VA of FIG. 4, and (B) is a partially enlarged view of (A). It is a top view of the gasket. (A) is a cross-sectional view of the engine seen from the VIA-VIIA viewing direction of FIG. 6, and (B) is a cross-sectional view showing another example of the constriction cooling means.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following, the front-back and left-right terms are used to specify the direction, but the front-back direction is the crank axis direction (longitudinal direction of the cylinder block), and the left-right direction is the direction orthogonal to the crank axis and the cylinder axis (short cylinder head). Hand direction). Regarding the front and back, the side where the timing chain is placed is the front, and the side where the mission is placed is the back. As a precaution, the directions are clearly shown in FIGS. 2 and 5 (A).

The vertical direction is the cylinder bore axis. Therefore, the plan view direction is the direction viewed from the cylinder bore axis direction, and the side view direction is the direction viewed from the crank axis direction and the direction orthogonal to the cylinder bore axis direction.

(1). Outline of internal combustion engine This embodiment is applied to an automobile internal combustion engine. First, an outline of the internal combustion engine will be described with reference to the schematic diagram of FIG. 1 (A).

The internal combustion engine includes a cylinder block 1 and a cylinder head 2 fixed to the upper surface of the cylinder block 1 as the core of the engine body, a cylinder head cover 3 is fixed to the upper surface of the cylinder head 2, and a cylinder head cover 3 is fixed to the lower surface of the cylinder block 1. The oil pan 4 is fixed. A front cover (chain cover, chain case) 5 that covers a timing chain (not shown) is fixed to the front surface (one end surface) of the cylinder block 1 and the cylinder head 2 with bolts.

A block jacket 6 that opens upward toward the cylinder head 2 is formed in the cylinder block 1, and a head jacket 7 is also formed inside the cylinder head 2. The cylinder block 1 and the cylinder head 2 are cast aluminum products, respectively.

A water pump 8 is arranged in a portion of the cylinder block 1 near the front end, and cooling water is sent from the water pump 8 to the block jacket 6 and the head jacket 7, but in the present embodiment, the cooling water has a set temperature. A two-system cooling system is adopted in which the cooling water mainly flows to the head jacket 7 in a lower state and flows to both the head jacket 7 and the block jacket 6 when the cooling water reaches a set temperature.

Therefore, the water supply passage 10 for the head and the water supply passage 11 for the block are branched from the discharge passage 9 of the water pump 8, and the first thermo valve 12 is arranged in the water supply passage 11 for the block, and the water supply passage 10 for the head is arranged. Communicates with the front end of the head jacket 7, and the water supply passage 11 for the block communicates with the portion near the front end of the block jacket 6.

A cooling water outlet 2a is opened at the rear end of the cylinder head 2, and a heater feed pipe line 13 and a radiator feed pipe line 14 are connected to the cooling water outlet 2a. The heater feed line 13 is connected to the inlet port of the heater core 15, but the heater return line 17 is connected to the outlet port of the heater core 15, and the heater return line 17 is the rear end of the cylinder head 2. It is connected to the relay unit 18 formed in. A CVT warmer 19 is inserted in the middle of the heater return pipe 17.

The relay portion 18 formed at the rear end of the cylinder head 2 is formed with a head flow passage 21 that opens toward the rear end of the cylinder block 1, while the cylinder block 1 is formed with a head flow passage 21. The front-rear longitudinal cooling water return passage 22 that communicates with the water pump 8 is integrally formed.

On the other hand, the radiator feed line 14 is connected to the upper tank of the radiator 23, and the radiator return line 24 is connected to the lower tank of the radiator 23. Then, a second thermo valve 26 for controlling water flow to the radiator 23 is arranged in the relay passage 25 communicating with the downstream end of the cooling water return passage 22, and the radiator return pipe 24 is placed in the port of the second thermo valve 26. Is connected.

When the temperature of the cooling water is lower than the set value of the second thermo valve 26, the entire amount of the cooling water flows into the cooling water return passage 22 via the heater return pipe 17. On the other hand, when the temperature of the cooling water exceeds the setting of the second thermo valve 26, most of the cooling water discharged from the head jacket 7 is sucked into the water pump 8 via the radiator 23, and the remaining part is sucked into the water pump 8. , The water is sucked into the water pump 8 via the heater return pipe 17 and the cooling water return passage 22.

(2). Basic structure of the cylinder block Next, a specific structure will be described with reference to the drawings shown in FIG. 1 (B) and below. The internal combustion engine of the present embodiment has three cylinders, and as shown in FIG. 2A, three cylinder bores 27 are formed side by side in the crank axis direction in the cylinder block 1. The group of cylinder bores 27 is surrounded by a block jacket 6, but in the present embodiment, the block jacket 6 is separated into a front block jacket 6a constituting a front portion and a main block jacket 6b other than the front block jacket 6a.

When the temperature of the cooling water is lower than the set temperature of the first thermo valve 12 (lower than the set temperature of the second thermo valve 26), most of the cooling water flows from the front block jacket 6a to the head jacket 7 to cool the cooling water. When the temperature of the water exceeds the set temperature of the first thermovalve 12, the water is also diverted to the block jacket 6 and flows from the main block jacket 6b to the head jacket 7 through one communication hole 28 shown in FIG. 1 (A).

The internal combustion engine of the present embodiment is for a vehicle and is mounted in the engine room. However, the crank axis is in a long posture in the vehicle width direction and the exhaust side is directed toward the front of the vehicle. Therefore, the transverse / front exhaust posture is provided. It is installed in the vehicle. Then, as shown in FIG. 2, the cooling water inflow port 30 communicating with the head flow passage 21 shown in FIG. 1 (A) opens upward at the rear portion of the portion of the cylinder block 1 located on the side of the exhaust side surface 29. Further, on the front side of the cooling water inflow port 30, a plurality of front and rear oil dropping passages 31 and an oil collecting groove 32 communicating with the oil dropping passages 31 are formed. Reference numeral 36 shown in FIG. 2 and the like is a head bolt insertion hole.

For example, as shown in FIGS. 2 and 1B, a cylindrical horizontally long boss body 37 long in the front-rear direction is integrally formed on the exhaust side surface 29 of the cylinder block 1, and the inside of the boss body 37 is described above. It forms a cooling water return passage 22.

(3). Suction structure by water pump As shown in FIG. 3, an expansion chamber 22a forming the end of the cooling water return passage 22 is formed in the front portion of the exhaust side surface 29 of the cylinder block 1 to form the expansion chamber 22a. Is opened toward the side, and the water pump 8 is arranged in a state where the expansion chamber 22a is closed.

As shown in FIG. 4, the water pump 8 is fixed to the main housing 44 fixed to the cylinder block 1, the water inlet 45 fixed to the main housing 44 from the side, and the pump fixed to the front surface of the main housing 44. A pump housing 47 that closes the chamber (swirl chamber) 46 and a pulley 49 that is rotatably held by the pump housing 47 via a bearing 48 are provided, and are arranged in the pump chamber 46 on a spindle 50 provided in the pulley 49. The impeller 51 is fixed.

Although not explicitly shown in FIG. 4, the relay passage 25 shown in FIG. 1 (A) is formed in the main housing 44, and the relay passage 25 communicates with the expansion chamber 22a of the cooling water return passage 22. .. The main housing 44 is fixed to the receiving seat 1a (see FIG. 3) of the cylinder block 1 with bolts.

As shown in FIG. 2 (A), the water inlet 45 is formed with a return port 45a that is open to the left and right outward, and the radiator return pipe 24 (FIG. 1 (A)) composed of a hose is formed in the return port 45a. ) Is connected. A second thermovalve 26 schematically shown in FIG. 1A is arranged in a space surrounded by the main housing 44 and the water inlet 45.

(4). Cooling water discharge structure As shown in FIG. 4, a front-rear and longitudinal discharge passage 9 communicates with the pump chamber 46, and a water supply passage 10 to the head is connected to the downstream end of the discharge passage 9. The horizontally long portion 10a of the above and the horizontally long portion 11a of the water supply passage 11 to the block communicate with each other. As shown by a solid line in FIG. 5A, the horizontally long portion 11a of the water supply passage 11 to the block is formed so as to straddle the main housing 44 and the cylinder block 1, and is formed at the back end portion of the horizontally long portion 11a. The vertically elongated portion 11b of the water supply passage 11 to the block communicates with (downstream end portion), and the vertically elongated portion 11b communicates with the front end portion of the main block jacket 6b.

As shown by the alternate long and short dash line in FIG. 5A, the horizontally long portion 10a of the water supply passage 10 to the head is also formed so as to straddle the main housing 44 and the cylinder block 1, and is formed in a state of straddling the horizontally long portion 10a. A vertically long portion 10b (see FIG. 2A) that communicates with the front block jacket 6a communicates with the front block jacket 6a. The horizontally long portion 10a of the water supply passage 10 for the head and the horizontally long portion 11a of the water supply passage 11 for the block are also formed in the cylinder block 1, and in FIG. 3, the horizontally long portions 10a and 11a formed in the cylinder block 1 are clearly shown. doing.

As shown in FIG. 5, the first thermovalve 12 is arranged in the horizontally long portion 11a of the water supply passage 11 to the block. The first thermovalve 12 has a valve seat plate 52, a front cage 53, a central shaft 54, a slider 55, a movable valve plate 56, and a spring 57.

The valve seat plate 52 is sandwiched and fixed between the cylinder block 1 and the main housing 44, and the spring 57 is supported by a flange 58 fixed to the central shaft 54. Further, the movable valve plate 56 is fixed to the slider 55, and a communication hole 59 is formed in a portion of the valve seat plate 52 that overlaps with the movable valve plate 56. The slider 55 is filled with temperature-sensitive wax, and when the temperature of the cooling water rises to a set value, the temperature-sensitive wax expands and the slider 55 and the movable valve plate 52 are separated from the valve seat plate 52. , Cooling water flows to the main block jacket 6b. The second thermo-valve 26 also has a structure in which the movable valve plate is moved by using temperature-sensitive wax like the first thermo-valve 12.

Then, as clearly shown in FIG. 5B, a hole is made in the portion of the valve seat plate 52 that does not overlap with the movable valve plate 56, and this hole is cooled even when the first thermovalve 12 is closed. It forms a leak passage 61 that allows water to flow slightly through the main block jacket 6b. A plurality of leak passages 61 may be provided. Further, the leak passage 61 can be provided in the movable valve plate 56. Alternatively, a spacer having a small size such as a washer is interposed between the valve seat plate 52 and the movable valve plate 56 so that a slight amount of water can flow even when the first thermo valve 12 is closed. Is also possible.

(5). Block jacket and related structure As described above, the block jacket 6 is separated into a front block jacket 6a and a main block jacket 6b, but as shown in FIG. 6, it has reached the front block jacket 6a. The cooling water is sent toward the head jacket 7 from the two communication holes 64 formed in the gasket 63. Therefore, the cylinder head 2 has water passage holes corresponding to the two communication holes 64.

Since the main block jacket 6b constitutes most of the block jacket 6, as shown in FIGS. 2A and 6, the block jacket exhaust side portion 65 located on the exhaust side across the group of cylinder bores 27 It has a block jacket intake side portion 66 located on the intake side with a group of cylinder bores 27 in between, and a block jacket side portion 67 that communicates the two, and further, a block jacket exhaust side portion 65 and a block jacket intake side. The portion 66 has two constricted portions 65a and 66a that are inserted toward the inter-bore portion 68.

Then, as shown in FIG. 7, a drilled passage (water passage) having an inclined posture in which one end is opened in the inter-bore portion 68, one end is opened in the constricted portion 66a of the block jacket intake side portion 66, and the other end is opened in the inter-bore portion 68. While the 69 is formed, the gasket 63 is formed with a relief hole 70 communicating with the other end of the drilled passage 69, and the cylinder head 2 is further communicated with the head jacket 7 and the relief hole 70. A water passage 71 is formed. By flowing the cooling water through the drilled passage 69, the cooling of the inter-bore portion 68 can be promoted.

As shown in FIG. 7, in the internal combustion engine of the present embodiment, the cylinder bore axis 72 is tilted by a slight angle θ with respect to the vertical line so that the exhaust side surface is tilted forward. Therefore, in the main block jacket 6b, the block jacket exhaust side portion 65 is low and the block jacket intake side portion 66 is high. Therefore, an air vent hole 74 is formed in a portion of the gasket 63 that overlaps the block jacket intake side portion 66 and is separated from the constricted portion 66a. The cylinder head 2 is formed with a water passage port 75 for communicating the air vent hole 74 and the head jacket 7. Although there are two air vent holes 74 in the front and rear, only one air vent hole 74 may be provided.

As shown in FIG. 6, at a portion of the gasket 63 that overlaps the downstream end of the main block jacket 6b, a water passage hole 76 for flowing cooling water to the head jacket 7 with the first thermovalve 12 open is formed. There is.

(6). Summary If there is no movement of cooling water in the main block jacket 6b during warm-up operation with the first thermo valve 12 closed, the cylinder block 1 has a temperature distribution in the circumferential direction of the bore and does not come into contact with the cooling water. Since the temperature between the bores 68 is the highest, the cooling water in contact with the constrictions 66a and 65a may cause a local boiling phenomenon. Then, it is insulated by steam due to boiling, and the inter-bore portion 68 becomes abnormally high temperature. Therefore, the temperature rise of the member may exceed the allowable heat resistant temperature of the member, cause knocking, or reduce the roundness of the cylinder bore 27. There is a risk of problems such as an increase in reduced blow-by gas.

On the other hand, in the present embodiment, even when the first thermovalve 12 is closed, a small amount of cooling water can flow to the main block jacket 6b through the leak passage 61, while the head jacket 7 is substantially. Since the entire amount of cooling water flows at high speed, a negative pressure (pressure difference) acts on the drilled passage 69 and the air vent hole 74 due to the Venturi effect (or ejector effect or pressure balance), resulting in cooling. Water is sucked into the head jacket 7 from the drilled passage 69 and the air vent hole 74.

In this case, if the intake side portion 66 of the block jacket is in a negative pressure state (a state in which the pressure is reduced by the pressure loss from the discharge pressure), the flow of cooling water may be impaired even if a negative pressure acts on the outlet of the drilled passage 69. Since the same amount of cooling water as the outflow flow rate flows into the main block jacket 6b through the leak passage 61, it is possible to prevent the block jacket intake side portion 66 from being in a negative pressure state, and to prevent the drilled passage 69 and air bleeding. The suction from the hole 74 can be ensured.

Furthermore, in the constricted portion 66a of the block jacket intake side portion 66, the cooling water comes into contact with the inter-bore portion 68 and has a higher temperature than other portions, so that convection is likely to occur due to the temperature difference between the upper and lower parts. However, since convection is promoted by the small amount of water flowing through the block jacket intake side portion 66, the cooling water existing in the constricted portion 66a is collected in the block jacket intake side portion 66 such as the drilled passage 69. A flow towards the air vent hole 74 is easily formed.

Therefore, the fluidity of the cooling water at the constricted portion 66a of the block jacket intake side portion 66 is ensured, but the cooling water flows from the block jacket exhaust side portion 65 toward the block jacket intake side portion 66. When a flow in which cooling water escapes from the constricted portion 66a to the head jacket 7 is formed in the block jacket intake side portion 66, a water flow is also formed in the block jacket exhaust side portion 65, and the cooling water does not stay in the constricted portion 65a. Absent. Therefore, running water always comes into contact with the inter-bore portion 68 at the pair of constricted portions 65a and 65b, and the upper portion of the inter-bore portion 68 can be cooled firmly to prevent heat spotting. Further, since the drilled passage 69 flows into the water passage port 71 communicating with the head jacket 7 via the back side of the constricted portion 65a having a high member temperature at the upper part of the bore-to-bore portion 68, the member temperature of the exhaust side constricted portion 65a can be reduced. Contribute. As a result, it is possible to prevent the cooling water from locally boiling at the constricted portions 65a and 66a, and to prevent the member from becoming abnormally high temperature.

In the present embodiment, since the cylinder block 1 is tilted by a slight angle θ so that the exhaust side is tilted forward, the suction of the cooling water from the block jacket intake side portion 66 is ensured. Therefore, it is possible to ensure the passage of water through the drilled passage 69 and the air vent hole 74.

Further, the discharge amount of the water pump is proportional to the rotation speed of the engine, and when the engine rotates at high speed, the circulation amount of the cooling water also increases, so that the cooling performance of the inter-bore portion 68 can be increased in proportion to the rotation speed. Therefore, the amount of cooling water is automatically adjusted so that the inter-bore portion 68 is cooled in just proportion. This point is one of the features of this embodiment.

As described above, in the present embodiment, the synergistic effect of the leak passage 61, the drill passage 69, and the air vent hole 74 prevents the member temperature rise in the inter-bore portion 68 and the local boiling of the cooling water in the constricted portions 65a and 66a. On the other hand, during the warm-up operation, most of the cooling water is allowed to flow through the head jacket 7 to realize early warm-up. Therefore, in the present embodiment, the drill passage 69 and the air vent hole 74 form a constriction cooling means.

As shown by the alternate long and short dash line in FIG. 7A, cooling water is flowed toward the head jacket 7 from the constricted portion 65a of the block jacket exhaust side portion 65 in addition to or instead of the drilled passage 69 described above. It is also possible to form a drilled passage 76.

As shown in FIG. 7B, a drilled passage 77 for flowing cooling water from the constricted portion 66a of the block jacket intake side portion 66 to the constricted portion 65a of the block jacket exhaust side portion 65 is formed between the bores, and a gasket is formed. A water passage hole 78 communicating with the head jacket 7 is formed in the vicinity of the outlet of the drilled passage 77 out of 63.

In this embodiment, the cooling water is sucked from the constricted portion 65a of the block jacket exhaust side portion 65 due to the pressure difference between the head jacket 7 and the block jacket exhaust side portion 65, but the two constricted portions 65a and 66a communicate with each other. At the same time, since the block jacket intake side portion 66 is not in a negative pressure state due to the presence of the air vent hole 74, the flow of cooling water from the block jacket intake side portion 66 to the block jacket exhaust side portion 65 is ensured. Cooling of the inter-bore portion 68 can be ensured. Further, in this embodiment, since the cooling water of the two constricted portions 65a and 66a is sucked up by the head jacket 7, it can be said that the effect of preventing local boiling is excellent.

The leak passage 61 can be formed at various sites. As an example, in FIG. 2B, a groove is formed on the upper surface of the partition wall 79 that separates the vertically elongated portion 10b of the water supply passage 10 for the head and the vertically elongated portion 11b of the water supply passage 11 for the block. Instead of or in addition to forming on the partition wall 79, it is also possible to form a punch hole in the gasket 63 to form a leak passage 61.

The invention of the present application can be embodied in various other ways. For example, as a valve for controlling water flow to the block jacket, an electromagnetic solenoid type or a motor type can also be used. Further, as an element of the constricted portion water passing means, it is also possible to form a water passing groove (split groove) for communicating the two constricted portions on the upper surface of the inter-bore portion.

The invention of the present application can be embodied in an internal combustion engine. Therefore, it can be used industrially.

1 Cylinder block 2 Cylinder head 6 Block jacket 6a Front block jacket 6b Main block jacket 7 Head jacket 8 Water pump 9 Discharge passage 10 Head water supply passage 11 Block water supply passage 12 1st thermo valve as an example of valve 52 Valve seat plate 53 Front cage 54 Central axis 55 Slider 61 Leak passage 65 Block jacket exhaust side part 65a Constriction part 66 Block jacket intake side part 66a Constriction part 68 Bore inter-bore part 69,76,77 Constriction part Drilled passage that constitutes water passage means

Claims (1)

A head jacket formed on the cylinder head to cool the cylinder head, a block jacket formed on the cylinder block to cool the cylinder block, and cooling water pumped from a water pump are sent to the head jacket. It has a water supply passage to the head and a water supply passage to the block that sends the cooling water pumped from the water pump to the block jacket.
While a valve that controls water flow according to the temperature of the cooling water is arranged in the water supply passage to the block,
The block jacket is a block jacket exhaust side portion located on the exhaust side across a group of cylinder bores, a block jacket intake side portion located on the intake side across the cylinder bore group, and a block jacket side portion that communicates both. The block jacket exhaust side portion and the block jacket intake side portion have a constricted portion that has entered toward the space between the bores.
Cooling water is supplied to the head jacket from a leak passage that allows a small amount of cooling water to flow to the block jacket even when the valve is closed, and from the constricted portion of the intake side portion of the block jacket or the constricted portion of the exhaust side portion of the block jacket. It is provided with a constriction cooling means that flows toward it.
Internal combustion engine.

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