JP2013160183A - Cooling structure of engine - Google Patents

Abstract

An object of the present invention is to increase the temperature of a cylinder block during warm-up operation of the engine and to cool the cylinder head during non-warm-up operation so as to suppress the occurrence of knocking and to keep the cylinder block at a high temperature to improve fuel consumption.
In an engine cooling structure in which cooling water flows independently to a head side cooling water passage 5 and a block side cooling water passage 6, an outlet side communication passage 24 and an introduction side communication passage 25 are provided when the engine is not warmed up. The head switching valve 26 and the block switching valve 29 are switched so that the cooling water flows independently through the head side cooling water passage 5 and the block side cooling water passage 6, respectively, while the engine warm-up is performed. During operation, the outlet side communication passage 24 and the introduction side communication passage 25 are opened, respectively, and the head switching valve 26 and the block switching are made so that the cooling water is circulated between the head side cooling water passage 5 and the block side cooling water passage 6. The valve 29 is switched and operated.
[Selection] Figure 1

Description

  The present invention relates to an engine cooling structure, and more particularly, to an engine cooling structure that suppresses occurrence of knocking at a high load and improves fuel consumption by allowing cooling water to flow independently through a cylinder head and a cylinder block.

In order to improve fuel efficiency, the cooling structure of the engine that is cooled by cooling water is designed to reduce knocking by lowering the temperature of the cooling water flowing to the cylinder head, and to increase the temperature of the cooling water flowing to the cylinder block. There is a two-system cooling system that improves fuel consumption by promoting the formation and reducing the friction due to the rise in oil temperature accompanying the rise in cooling water temperature.
FIG. 6 shows a cooling structure of the dual-system cooling engine. In FIG. 6, 101 is an engine, 102 is a cylinder head, 103 is a cylinder block, and 104 is an oil pan. The cooling structure of the engine 101 includes a head side cooling water passage 105 formed in the cylinder head 102, a block side cooling water passage 106 formed in the cylinder block 103, and a radiator 107 that radiates the cooling water.
The cooling water that has flowed out of the head side cooling water passage 105 and the block side cooling water passage 106 passes through the head side thermostat 108 and the block side thermostat 109 and joins, and is guided to the radiator 107 by the cooling water outlet passage 110. The cooling water radiated by the radiator 107 is branched and guided to the head side cooling water passage 105 and the block side cooling water passage 106 by the cooling water introduction passage 111. The cooling water introduction passage 111 is provided with a water pump 112 that pumps the cooling water.
In the cooling structure of the engine 101, the cooling water radiated by the radiator 107 is guided to the engine 101 side by the cooling water introduction passage 111 to be branched, and the head side cooling water passage 105 of the cylinder head 102 and the block side cooling of the cylinder block 103 are separated. It flows independently in the water passage 106. The flow rate of the cooling water flowing through the head side cooling water passage 105 and the block side cooling water passage 106 is controlled by the head side thermostat 108 and the block side thermostat 109 on each outlet side, and passes through the head side thermostat 108 and the block side thermostat 109. It merges later and is guided to the radiator 107 by the cooling water outlet passage 110.

JP 2001-236831 A

By the way, in the engine cooling structure shown in FIG. 6, the cooling water radiated by the radiator is diverted and flows independently into the head side cooling water passage of the cylinder head and the block side cooling water passage of the cylinder block.
For this reason, the temperature of each coolant flowing into the cylinder head and cylinder block is the same, and it is not possible to make a large difference in the coolant temperature between the cylinder head and cylinder block, which is sufficient for non-warm-up operation such as high load operation. There is a problem that the knock is not improved.
Since the engine knocks at a high load, the ignition timing is delayed to avoid knocking, but the combustion efficiency is deteriorated by delaying the ignition timing. On the other hand, knocking can be suppressed by lowering the temperature of the cooling water flowing to the cylinder head and cooling the combustion chamber. However, in the conventional dual cooling structure, the temperature of the cooling water flowing into the cylinder head and the cylinder block is the same. For this reason, the temperature of the cylinder block also gets cold.
The higher the temperature of the cylinder block, the smaller the friction due to the engine oil temperature rise. Therefore, if the cooling water flowing into the cylinder head is lowered in the conventional two-system cooling structure, the temperature of the cooling water flowing into the cylinder block is also reduced. As a result, the friction cannot be sufficiently improved. In addition, when the wall surface temperature of the cylinder block is low, there is a problem that HC which is a final combustion component of the fuel increases and fuel consumption deteriorates.

The engine cooling structure shown in FIG. 6 improves the temperature rise of the cooling water temperature by stopping the flow of the cooling water with a thermostat during the warm-up operation of the engine. This is because if cooling water flows inside the engine, the cooling water radiates heat in the cooling water passage outside the engine, and the total amount of cooling water passing through the engine increases, so the temperature rise of the cooling water deteriorates. Because.
However, by stopping the flow of cooling water inside the engine, natural convection due to heat occurs in the cylinder head with a large amount of heat generation, so the temperature rise of the cooling water is good, but in the cylinder block with a small amount of heat generation, the temperature of the cooling water The rise will be slow and the engine oil temperature rise will also be slow. In particular, since the lower part of the cylinder block (oil pan side) does not receive the combustion heat directly, the temperature rise is slow. If the temperature of the cylinder block is low, the friction is increased, which leads to deterioration in fuel consumption during warm-up operation. Therefore, there is sufficient room for improvement in order to improve the temperature rise of the coolant temperature during the warm-up operation and to improve the fuel consumption.

  In the engine cooling structure, the temperature of the cylinder block is quickly increased during engine warm-up operation, and the temperature of the cylinder head is decreased during non-warm-up operation such as high load operation to suppress the occurrence of knocking. And it aims at ensuring a cylinder block at high temperature and improving the fuel consumption of an engine.

  The present invention includes a head side cooling water passage formed in a cylinder head of an engine, a block side cooling water passage formed in a cylinder block of the engine, a radiator that radiates heat of the engine cooling water, and the head side cooling water passage. And a cooling water outlet passage for guiding cooling water flowing out from the block side cooling water passage to the radiator, and a cooling water introduction for guiding cooling water radiated by the radiator to the head side cooling water passage and the block side cooling water passage A cooling structure for an engine that flows through the head side cooling water passage and the block side cooling water passage independently, and the radiator radiates the cooling water flowing out from the head side cooling water passage. Consists of a radiator for the head and a radiator for the block that radiates the cooling water flowing out from the block-side cooling water passage The cooling water outlet passage includes a head cooling water outlet passage for guiding the cooling water flowing out from the head side cooling water passage to the head radiator and a cooling water flowing out from the block cooling water passage to the block radiator. The cooling water introduction passage includes a head cooling water introduction passage that guides the cooling water radiated by the head radiator to the head side cooling water passage and the block radiator. A block cooling water introduction passage that guides the radiated cooling water to the block side cooling water passage; and the vicinity of the upstream end of the head cooling water lead-out passage on the cylinder head side and the block cooling water lead-out passage. The outlet side communication passage is connected to the vicinity of the upstream end on the cylinder block side, and the vicinity of the downstream end on the cylinder head side of the cooling water introduction passage for the head And the vicinity of the downstream end of the cylinder block of the cooling water introduction passage for the block are connected by an introduction side communication passage, and a head switching valve is disposed at a connection portion between the head cooling water extraction passage and the discharge side communication passage. In addition, a block water pump is disposed at a connection portion between the block cooling water lead-out passage and the lead-out side communication passage, and a head water is provided at a connection portion between the head cooling water introduction passage and the introduction-side communication passage. A pump is disposed, and a block switching valve is disposed at a connection portion between the block cooling water introduction passage and the introduction side communication passage, and the head switching valve and the block switching valve are not heated by the engine. When the machine is in operation, the outlet side communication passage and the introduction side communication passage are closed, and the cooling water flows independently through the head side cooling water passage and the block side cooling water passage. While the engine is warming up, the outlet side communication passage and the introduction side communication passage are opened, and the cooling water is circulated between the head side cooling water passage and the block side cooling water passage. It is characterized in that the switching operation is performed.

In the present invention, when the engine is not warmed up, the cooling water flows independently through the head side cooling water passage and the block side cooling water passage, so that the temperature of the cooling water flowing into the cylinder head and the cylinder block can be differentiated. It is possible to suppress the knocking by maintaining the cooling of the cylinder head when the engine is heavily loaded.
Furthermore, this invention can prevent the wall temperature of the cylinder block from decreasing, and can suppress the decrease in the temperature of oil in the cylinder block to prevent an increase in friction. Thereby, HC which is an unburned component can be reduced and the fuel consumption of an engine can be improved.
In general, the amount of heat generated by the cylinder head is larger than that of the cylinder block. Therefore, according to the present invention, the cooling water can be circulated between the cylinder head and the cylinder block by circulating the cooling water between the head side cooling water passage and the block side cooling water passage during the warm-up operation of the engine. The amount of heat can be transferred to the cylinder block, and the temperature of the cylinder block can be raised. Thereby, the wall surface temperature of the cylinder block can be raised and the fuel efficiency of the engine can be improved.

FIG. 1 is a configuration diagram of an engine cooling structure. (Example) FIG. 2 is a perspective view of the radiator. (Example) FIG. 3 is a circuit configuration diagram of control means for controlling the rotation of the block water pump. (Example) FIG. 4 is a diagram showing the flow of cooling water during non-warm-up operation of the engine. (Example) FIG. 5 is a diagram showing the flow of cooling water during engine warm-up operation. (Example) FIG. 6 is a configuration diagram of an engine cooling structure. (Conventional example)

  Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an engine having a plurality of cylinders arranged in a row. The engine 1 is mounted on a vehicle or the like and includes a cylinder head 2, a cylinder block 3, and an oil pan 4. The cylinder head 2 is located at the upper part of the engine 1 and forms the upper part of the combustion chamber. The cylinder block 3 forms a lower part of the combustion chamber, and includes a piston in the cylinder.
The engine 1 has a structure in which cooling water is cooled by flowing from one end side in the cylinder row direction toward the other end side in the cylinder row direction. The cooling structure of the engine 1 includes a head-side cooling water passage 5 formed in the cylinder head 2, a block-side cooling water passage 6 formed in the cylinder block 3, a radiator 7 that radiates cooling water, and a head-side cooling water passage. 5 and the cooling water outlet passage 8 for guiding the cooling water flowing out from the block side cooling water passage 6 to the radiator 7, and the cooling for guiding the cooling water radiated by the radiator 7 to the head side cooling water passage 5 and the block side cooling water passage 6. And a water introduction passage 9. The cooling structure of the engine 1 is a two-system cooling structure in which cooling water flows independently through the head-side cooling water passage 5 and the block-side cooling water passage 6.

The head-side cooling water passage 5 includes a head-side outlet 10 through which the cooling water flows out to the outside at the other end side in the cylinder row direction, and the head side through which the cooling water flows into one end side in the cylinder row direction of the cylinder head 2. An inflow port 11 is provided. The block-side cooling water passage 6 includes a block-side outflow port 12 through which cooling water flows out to the outside at the other end side in the cylinder row direction, and a block side through which cooling water flows into one end side in the cylinder row direction of the cylinder block 3. An inflow port 13 is provided.
The radiator 7 includes a cooling fan, and as shown in FIG. 2, the radiator for head 14 that radiates the cooling water flowing out from the head side cooling water passage 5 and the cooling water that flows out from the block side cooling water passage 6 are radiated. The block radiator 15 is configured to be divided. The head radiator 14 includes a head introduction portion 16 that introduces a raised cooling water, and a head lead-out portion 17 that derives the radiated cooling water. The block radiator 15 includes a block introduction unit 18 that introduces the raised cooling water, and a block derivation unit 19 that derives the radiated cooling water.
Since the radiator 7 is divided into the head radiator 14 and the block radiator 15, it can treat different cooling waters at the same time without impairing the mountability to the vehicle as much as possible. In the dual cooling structure, the division ratio is set so that the capacity of the head radiator 14 is larger than the capacity of the block radiator 15 in order to keep the temperature of the cylinder head 2 low and keep the temperature of the cylinder block 3 high. .
The ratio between the capacity of the head radiator 14 and the capacity of the block radiator 15 is determined in consideration of the heat generation ratio of the engine 1. The rate of heat generation of the engine 1 is approximately 7: 3 between the cylinder head 2 and the cylinder block 3. However, in consideration of the necessity of quick cooling when the temperature of the cylinder block 3 greatly exceeds the control target value, the ratio division ratio between the capacity of the head radiator 14 and the capacity of the block radiator 15 is set to 6 here. : Set to 4-7: 3.

The cooling water outlet passage 8 includes a head cooling water outlet passage 20 for guiding the cooling water flowing out from the head side cooling water passage 5 to the head radiator 14, and a cooling water flowing out from the block side cooling water passage 6 in the block radiator. 15 and a block cooling water outlet passage 21 that leads to 15. The head cooling water outlet passage 20 has an upstream side connected to the head side outlet 10 of the head side cooling water passage 5 and a downstream side connected to the head introduction portion 16 of the head radiator 14. The block cooling water lead-out passage 21 has an upstream side connected to the block side outlet 12 of the block side cooling water passage 6 and a downstream side connected to the block introduction portion 18 of the block radiator 15.
The cooling water introduction passage 9 includes a head cooling water introduction passage 22 that guides the cooling water radiated by the head radiator 14 to the head side cooling water passage 5, and a block side cooling of the cooling water radiated by the block radiator 15. The block cooling water introduction passage 23 is led to the water passage 6. The head cooling water introduction passage 22 has an upstream side connected to the head outlet 17 of the head radiator 14 and a downstream side connected to the head side inlet 11 of the head side cooling water passage 5. The block cooling water introduction passage 23 has an upstream side connected to the block lead-out portion 19 of the block radiator 15 and a downstream side connected to the block side inlet 13 of the block side cooling water passage 6.
The head cooling water outlet passage 20 and the block cooling water outlet passage 21 are connected by an outlet side communication passage 24. The outlet side communication passage 24 has an upstream end connected to the head side outlet 10 of the head cooling water outlet passage 20 and an upstream end connected to the block side outlet 12 of the block cooling water outlet passage 21. Connected. The head cooling water introduction passage 22 and the block cooling water introduction passage 23 are connected by an introduction side communication passage 25. The introduction side communication passage 25 includes a vicinity of the downstream end connected to the head side inlet 11 of the head cooling water introduction passage 22 and a vicinity of the downstream end connected to the block side inlet 13 of the block cooling water introduction passage 23. Connected.

A head switching valve 26 is disposed at a connection portion between the head cooling water outlet passage 20 and the outlet side communication passage 24. A block water pump 27 is disposed at a connecting portion between the block cooling water outlet passage 21 and the outlet side communication passage 24. Further, a head water pump 28 is disposed at a connection portion between the head cooling water introduction passage 22 and the introduction side communication passage 25. A block switching valve 29 is disposed at a connection portion between the block cooling water introduction passage 23 and the introduction side communication passage 25.
The head switching valve 26 closes the lead-out side communication passage 24 and closes the head-side communication passage 24 during non-warm-up operation of the engine 1 such as high-load operation in which the temperature of the coolant in the head coolant discharge passage 20 is higher than a set temperature. Switching operation is performed to open the cooling water outlet passage 20 (see FIG. 4), and the cooling water in the head side cooling water passage 5 is caused to flow into the head cooling water outlet passage 20. On the other hand, the head switching valve 26 opens the outlet side communication path 24 and warms up the head switching valve 26 during the warm-up operation of the engine 1 where the temperature of the cooling water in the head cooling water outlet path 20 is lower than the set temperature. The switching operation is performed so as to close the downstream head cooling water outlet passage 20 (see FIG. 5), and the cooling water flowing out from the head side cooling water passage 5 flows to the block side cooling water passage 6 side.
The block switching valve 29 closes the introduction side communication passage 25 and closes the block cooling water introduction passage 23 when the temperature of the cooling water in the block cooling water introduction passage 23 is equal to or higher than the set temperature when the engine 1 is not warmed up. Is switched to open (see FIG. 4), and the cooling water in the block cooling water introduction passage 23 is caused to flow to the block side cooling water passage 6. On the other hand, the block switching valve 29 opens the introduction-side communication passage 25 during the warm-up operation of the engine 1 at which the temperature of the cooling water in the block cooling water introduction passage 23 is lower than the set temperature, and is more than the block switching valve 29. The switching operation is performed so that the upstream block cooling water introduction passage 23 is closed (see FIG. 5), and the cooling water flowing out from the block side cooling water passage 6 flows to the head side cooling water passage 5 side.
As a result, the head switching valve 26 and the block switching valve 29 close the outlet side communication passage 24 and the introduction side communication passage 25 during the non-warm-up operation of the engine 1, respectively, so that the head side cooling water passage 5 and the block side While the switching operation is performed so that the cooling water flows independently into the cooling water passage 6, the outlet side communication passage 24 and the introduction side communication passage 26 are opened during the warm-up operation of the engine 1, and the head side cooling water passage 5 and The switching operation is performed so that the cooling water is circulated between the block side cooling water passages 6.

As shown in FIG. 3, the block water pump 27 includes a pump impeller 30 that pumps cooling water, and includes a drive motor 31 that drives the pump impeller 30. The drive motor 31 is a direct current motor that can rotate the pump impeller 30 in the forward direction and the reverse direction by switching the rotation direction in the direction of the supplied current. A control means 35 is connected to the + electrode 32 and the − electrode 33 of the drive motor 31 via a changeover switch 34 that can switch between positive and negative current. The control means 35 includes a power source 36 for supplying current to the driving motor, a head side water temperature sensor 37 provided at the head side outlet 10 of the cylinder head 2, and a block provided at the block side outlet 12 of the cylinder block 3. A side water temperature sensor 38 is connected.
The control means 34 determines that the engine 1 is in a non-warm-up operation when the temperature of the cooling water detected by the head-side water temperature sensor 37 and the block-side water temperature sensor 38 is equal to or higher than the set temperature, and the block water pump 27 The changeover switch 34 is switched so as to rotate in the forward direction. The block water pump 27 pumps the coolant toward the downstream side of the block coolant outlet passage 21 by forward rotation.
On the other hand, the control means 34 determines that the engine 1 is in the warm-up operation when the temperature of the cooling water detected by the head-side water temperature sensor 37 and the block-side water temperature sensor 38 is lower than the set temperature. By switching the changeover switch 34 so as to rotate the water pump 27 in the reverse direction, the current direction is reversed from that in the non-warm-up operation. The block water pump 27 pumps the coolant toward the upstream side of the block coolant outlet passage 21 by reverse rotation.
As a result, the block water pump 27 is rotated in the opposite direction to the non-warm-up operation during the warm-up operation of the engine 1, thereby releasing the cooling water flowing out from the head-side cooling water passage 5. The passage 24 is caused to flow to the block-side cooling water passage 6 through the block cooling water outlet passage 21.
The head water pump 28 is a water pump driven by a belt driven by a crank pulley of the engine 1 or an electric motor, as in the existing water pump. The head water pump 28 can rotate only in the forward direction, and pumps the coolant toward the downstream side of the head coolant introduction passage 22 by the forward rotation.
In this embodiment, the head switching valve 26 and the block water pump 27 are built in the lead-out side case 39, and the head water pump 28 and the block switching valve 29 are built in the lead-in side case 40.

Next, the operation will be described.
In the cooling structure of the engine 1, the head side cooling water passage 5, the block side cooling water passage 6, the head radiator 14, the block radiator 15, the head cooling water outlet passage 20, and the block cooling water outlet. A passage 21, a head cooling water introduction passage 22, a block cooling water introduction passage 23, a discharge side communication passage 24, an introduction side communication passage 25, a head switching valve 26, a block water pump 27, A head water pump 28 and a block switching valve 29 are provided, which makes it possible to completely separate the temperature control between the cylinder head 2 and the cylinder block 3, and to improve the cooling performance of the cylinder head 2 during non-warm-up operation. Maintaining and raising the temperature rise of cooling water during warm-up operation.
When the engine 1 is not warmed up, as shown in FIG. 4, the head switching valve 26 and the block switching valve 29 are switched from the broken line to the position indicated by the solid line, and the derivation side communication path 24 and the introduction side communication path 25 are switched. Are closed, and the head cooling water outlet passage 20 and the block cooling water introduction passage 23 are opened. The head water pump 28 and the block water pump 27 are rotated in the forward direction when the engine 1 is not warmed up. The cooling water is circulated independently to the head side cooling water passage 5 of the cylinder head 2 and the block side cooling water passage 6 of the cylinder block 3 by separate head water pumps 28 and block water pumps 27, respectively. It is controlled to reach the target temperature.
Thereby, since the cooling water of the cylinder head 2 and the cylinder block 3 is not mixed, at the time of non-warm-up operation such as high load operation, the cooling water temperature of the cylinder head 2 is made lower than that of the existing cooling structure, and the cylinder block 3 The cooling water temperature can be increased.
If the cooling water temperature of the block side cooling water passage 6 is kept high during non-warm-up operation, the temperature between the cylinders of the cylinder block 3 that has no cooling water passage or is not sufficiently secured becomes the highest, and sufficient strength is maintained. The temperature may disappear. In the vicinity of the deck surface of the cylinder block 3, there is a space of a combustion chamber in which combustion is performed. Therefore, a high temperature on the deck surface of the cylinder block 3 causes knocking.
Since the cooling enhancement by lowering the cooling water temperature of the cylinder head 2 is effective for cooling the deck surface of the cylinder block 3, the above problem can be solved. Since the heat between the cylinders at the high temperature of the cylinder block 3 moves to the cooling water of the cylinder head 2 through the head gasket, the temperature of the cooling water flowing through the head side cooling water passage 5 of the cylinder head 2 is kept low. The temperature of the deck surface of the block 3 can be lowered.
Conventionally, in the present invention, even in a high load region where the temperature of the cooling water flowing through the block-side cooling water passage 6 had to be lowered in order to maintain a safe temperature between the cylinders of the cylinder block 3, the cylinder head 2 Since the temperature difference between the cylinder block 3 and the cylinder block 3 can be increased by cooling them independently, strength anxiety and knock deterioration due to temperature rise can be prevented while keeping the temperature of the cylinder block 3 high.

On the other hand, during the warm-up operation of the engine 1, as shown in FIG. 5, the head switching valve 26 and the block switching valve 29 are switched from the broken line to the position indicated by the solid line. 25 is opened, and the downstream side of the head cooling water outlet passage 20 and the downstream side of the block cooling water introduction passage 23 are closed. Yes. The head water pump 28 is rotated in the forward direction during the warm-up operation of the engine 1 as in the non-warm-up operation. On the other hand, the block water pump 27 is rotated in the opposite direction to the non-warm-up operation during the warm-up operation of the engine 1. The cooling water is circulated between the head side cooling water passage 5 and the block side cooling water passage 6 through the open outlet side communication passage 24 and the introduction side communication passage 25.
As described above, the cooling structure of the engine 1 is configured such that when the engine 1 is warmed up, the block water pump 27 is rotated in the opposite direction to that during the non-warmup operation so that the cooling water flowing out from the cylinder head 2 is discharged to the cylinder block. It is possible to circulate positively toward 3 and circulate. As a result, the amount of heat of the cylinder head 2 can be transferred to the cylinder block 3 as much as possible, the temperature of the oil in the cylinder block 3 can be quickly raised, and the cooling water can be prevented from radiating heat to the outside of the engine. . Further, since the amount of cooling water to be warmed is equivalent to the case where the existing cooling water flow is stopped, the present invention capable of improving the heat transfer by the flow is effective in shortening the warm-up time and improving the fuel consumption.
The reason why the block water pump 27 is rotated in the reverse direction is to improve the flow rate and flow rate of the cooling water. In order for the cooling water to receive more heat from the wall surface forming the combustion chamber, it is important to improve the flow rate of the cooling water and improve heat transfer. However, the cooling water passage inside the engine has a complicated structure, and the pressure loss is large. Therefore, the flow rate and flow rate of cooling water in the engine as a whole are reduced by preventing the water pump from pushing out the water. End up.
The cooling structure of the engine 1 counteracts the decrease in the flow rate / flow velocity of the cooling water, and thus reverses the rotation of the block water pump 27 to assist the ability of circulating the cooling water by the head water pump 28. The flow rate / flow velocity per unit time of the cooling water circulating inside the engine can be improved, the temperature of the cooling water can be increased uniformly and quickly, and the fuel consumption of the engine 1 during warm-up can be improved.

Thus, the cooling structure of the engine 1 allows the cooling water to flow independently through the head side cooling water passage 5 and the block side cooling water passage 6 when the engine 1 is not warmed up. It is possible to make a difference in the temperature of the cooling water that flows in, and to maintain the cooling of the cylinder head 2 and suppress knocking when the engine 1 is under a high load.
Further, the cooling structure of the engine 1 can prevent the wall surface temperature of the cylinder block 3 from decreasing, and can suppress the temperature decrease of the oil in the cylinder block 3 to prevent an increase in friction. Thereby, HC which is an unburned component can be reduced and the fuel consumption of the engine 1 can be improved.
In general, the amount of heat generated by the cylinder head 2 is larger than that of the cylinder block 3. Therefore, in the cooling structure of the engine 1, the cooling water is circulated between the head side cooling water passage 5 and the block side cooling water passage 6 during the warm-up operation of the engine 1. Thus, the cooling water can be circulated, the amount of heat of the cylinder head 2 can be transferred to the cylinder block 3, and the temperature of the cylinder block 3 can be raised. Thereby, the wall surface temperature of the cylinder block 3 can be raised, and the fuel consumption of the engine 1 can be improved.

As shown in FIG. 2, the radiator 7 is configured by dividing a normal radiator into a head radiator 14 and a block radiator 15. The increase in the cooling water charge is only for the cooling water passages of the block cooling water outlet passage 21 and the block cooling water introduction passage 23 connecting the block side cooling water passage 6 of the cylinder block 3 and the block radiator 15. Yes, a big increase. For this reason, since the amount of the radiator is not required to be changed, the radiator 7 having the same size as that of the existing radiator can be used, and the mountability in the engine room is not deteriorated. Since most of the cooling water receives heat from the cylinder head 2, the division ratio of the head radiator 14 to the block radiator 15 is increased so that the cooling temperature can be kept lower.
However, when the engine 1 is provided with a charger and a water-cooled intercooler is added, it is necessary to increase the cooling water capacity of the radiator. When the intercooler is additionally provided in the block cooling water introduction passage 23, the cylinder block 3 is easily maintained at a high temperature by the cooling water warmed by the intercooler. In the high load operation region where the amount of heat received from the block wall surface of the cylinder block 3 or the intercooler is large, considering that the cooling function is insufficient only with the cooling fan provided in the radiator 7, the cooling water capacity of the radiator 7 is reduced. The cooling function may be increased to ensure a sufficient cooling function.
The radiator 7 is divided into a head radiator 14 and a block radiator 15, and the division ratio is set so that the capacity of the head radiator 14 is larger than the capacity of the block radiator 15. The temperature of the cylinder head 2 can be lowered, the temperature of the cylinder block 3 can be kept high, and when the temperature of the cylinder block 3 greatly exceeds the control target value, it can be quickly cooled.

  In the above-described embodiment, the radiator 7 is divided into the head radiator 14 and the block radiator 15. However, even if two independent radiators having a reduced water capacity are used, the cylinder head 2 and the cylinder block 3 are separated. Cooling water can flow independently.

  According to the present invention, the temperature of the cylinder block is quickly raised during engine warm-up operation, the temperature of the cylinder head is cooled during non-warm-up operation such as high load operation, and the occurrence of knocking is suppressed. It is possible to ensure high temperature and improve the fuel efficiency of the engine, and it can be applied to an engine equipped with a cooling device using cooling water.

1 Engine 2 Cylinder Head 3 Cylinder Block 5 Head Side Cooling Water Passage 6 Block Side Cooling Water Passage 7 Radiator 8 Cooling Water Leading Passage 9 Cooling Water Introducing Passage 14 Head Radiator 15 Block Radiator 20 Head Cooling Water Leading Passage 21 For Block Cooling water outlet passage 22 Head cooling water introduction passage 23 Block cooling water introduction passage 24 Outlet side communication passage 25 Introduction side communication passage 26 Head switching valve 27 Block water pump 28 Head water pump 29 Block switching valve 30 Pump Impeller 31 Drive motor 34 Changeover switch 35 Control means 36 Power supply 37 Head side water temperature sensor 38 Block side water temperature sensor

Claims (3)

  A head side cooling water passage formed in the cylinder head of the engine, a block side cooling water passage formed in the cylinder block of the engine, a radiator for radiating the cooling water of the engine, the head side cooling water passage and the block side A cooling water outlet passage for guiding cooling water flowing out from the cooling water passage to the radiator; and a cooling water introduction passage for guiding cooling water radiated by the radiator to the head side cooling water passage and the block side cooling water passage. In the engine cooling structure in which cooling water flows independently to the head side cooling water passage and the block side cooling water passage, the radiator includes a head radiator that radiates the cooling water flowing out from the head side cooling water passage; A block radiator for radiating the cooling water flowing out from the block side cooling water passage, and the cooling The lead-out passage is a head cooling water lead-out passage that leads the cooling water flowing out from the head-side cooling water passage to the head radiator and a block cooling passage that guides the cooling water that flows out from the block cooling water passage to the block radiator. The cooling water introduction passage is constituted by a water outlet passage, and the cooling water introduction passage is a cooling water introduction passage for guiding the cooling water radiated by the head radiator to the head side cooling water passage and the cooling heat radiated by the block radiator. A cooling water introduction passage for the block that guides water to the cooling water passage for the block side, and an upstream end vicinity of the cylinder head side of the cooling water outlet passage for the head and the cylinder block side of the cooling water outlet passage for the block And the vicinity of the downstream end of the head cooling water introduction passage on the cylinder head side and the block. A cooling water introduction passage is connected to the downstream end of the cylinder block in the vicinity of the downstream end of the cylinder block by an introduction side communication passage, and a head switching valve is disposed at a connection portion between the head cooling water lead-out passage and the lead-out side communication passage. A block water pump is disposed at a connection portion between the block cooling water outlet passage and the outlet side communication passage, and a head water pump is disposed at a connection portion between the head cooling water introduction passage and the introduction side communication passage. And a block switching valve is disposed at a connection portion between the block cooling water introduction passage and the introduction side communication passage, and the head switching valve and the block switching valve are not warmed up by the engine. Occasionally, the outlet side communication path and the introduction side communication path are closed, and switching is performed so that cooling water flows independently through the head side cooling water path and the block side cooling water path. On the other hand, during the warm-up operation of the engine, the outlet side communication passage and the introduction side communication passage are opened to circulate the cooling water between the head side cooling water passage and the block side cooling water passage. Engine cooling structure characterized by switching operation to   The block water pump is rotated in a direction opposite to that during non-warm-up operation during the warm-up operation of the engine, and the discharge-side communication passage opens the cooling water flowing out from the head-side cooling water passage. 2. The engine cooling structure according to claim 1, wherein the cooling water is caused to flow to the block-side cooling water passage through a block cooling water outlet passage.   The radiator is divided into a head radiator that radiates cooling water flowing out from the head-side cooling water passage and a block radiator that radiates cooling water flowing out from the block-side cooling water passage. 2. The engine cooling structure according to claim 1, wherein the division ratio is set so that the capacity of the radiator is larger than the capacity of the block radiator.

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