JP2002097959A - Cooling structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling structure of an internal combustion engine capable of suppressing residual gas temperature lowering and preventing knocking at a low cost with a simple structure capable of controlling the flow of coolant to a cylinder and a cylinder head without retention of the coolant in the cylinder according to the temperature of the coolant. SOLUTION: This cooling structure of the internal combustion engine comprises a first coolant circulating system having a first thermostat 5 for regulating coolant circulating amount between a radiator 10 and the internal combustion engine and a second coolant circulating system having a second thermostat 20 controlled so as to circulate the coolant to the cylinder 2 and the cylinder head 3 parallel with each other when the temperature of the coolant is below a specified temperature and to circulate the coolant from the cylinder 1 to the cylinder head 3 in series when the temperature of the coolant is higher than the specified temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure of an internal combustion engine using a cooling liquid.

[0002]

2. Description of the Related Art In order to finely cool an internal combustion engine in accordance with the operating state of the engine, examples have already been proposed in which pipes are respectively connected to a cylinder and a cylinder head to perform cooling control independently of each other.

For example, in the example described in Japanese Patent Application Laid-Open No. 2000-73770, as shown in FIG. 19, a feed passage 04 branches off at a switching valve 06 and a cylinder 02 and a cylinder head 03 of an internal combustion engine 01 as shown in FIG. Switching valve
By the operation of 06, the cooling water can be switched and supplied to the cylinder 02 and the cylinder head 03. The switching valve 06 is operated via a driving device 013 based on a control signal of the control unit 012.

[0004] Cooling water can be moved from the cylinder 02 to the cylinder head 03 as in a normal internal combustion engine, and a return passage 05 extends from the cylinder head 03. In addition to the switching valve 06, a thermostat 08 is provided in the feed passage 04 connected to the water pump 07. The thermostat 08 is directly connected to the feed passage 04 from the return passage 05 via the radiator 09 and the return passage 05. The cooling liquid can be flown by switching the bypass passage 010 to be used.

When the engine load is low, the switching valve 06 is controlled to control the cylinder as shown by the solid arrows in FIG.
The coolant flow to 02 is cut off and circulated only to the cylinder head 03.At low temperatures, the thermostat 08 closes the passage passing through the radiator 09, opens the bypass passage 010, and the water pump 07 connects only to the cylinder head 03. The coolant that does not pass through the radiator 09 is circulated to suppress the temperature drop of the residual gas in the combustion chamber.

When the engine is under a high load, the switching valve 06 is connected to the cylinder 02
The coolant is switched so that the coolant flows through it, and the thermostat 08 is switched so that the coolant circulates through the radiator 09.
The entire engine is cooled by circulating through the cylinder head 03.

[0007]

As described above, the switching valve 06 is operated in accordance with the engine load state to control the cooling of the cylinder 02 and the cylinder head 03. The unit 012 and the driving device 013 are required, and the structure is complicated and the cost is high.

At low engine load, the coolant circulates only through the cylinder head 03 and does not flow through the cylinder 02.
Since the coolant stays in the water jacket of 02 and the coolant flows only through the cylinder head 03, the effect of suppressing the temperature drop of the residual gas in the cylinder may be hindered. When the cooling of the cylinder head is required, the cooling of the cylinder head portion may be delayed due to the staying cooling liquid of the cylinder portion heated and knocking may occur.

The present invention has been made in view of the above point, and an object thereof is to control the flow of the coolant to the cylinder and the cylinder head without causing the coolant to stay in the cylinder according to the coolant temperature. An object of the present invention is to provide an inexpensive cooling structure for an internal combustion engine that has a simple structure to be controlled and is expected to have an effect of suppressing a temperature decrease of residual gas and an effect of preventing knocking.

[0010]

In order to achieve the above object, the invention according to the first aspect of the present invention includes a first thermostat for adjusting a circulation amount of a coolant between a radiator and an internal combustion engine. The first coolant circulation system controls the coolant to circulate in parallel to the cylinder and the cylinder head when the temperature is lower than a predetermined coolant temperature, and to circulate the coolant in series from the cylinder to the cylinder head when the temperature is higher than the predetermined coolant temperature. A cooling structure for an internal combustion engine comprising a second coolant circulation system having a second thermostat.

With the second thermostat of the second coolant circulation system, the coolant is circulated in parallel to the cylinder and the cylinder head at a low temperature, and the coolant is circulated from the cylinder to the cylinder head at a high temperature. Control and a drive device are unnecessary, the structure is simplified, and the cost can be reduced.

At a low temperature, the coolant is circulated directly to the cylinder head, and the coolant is also supplied to the cylinder, so that the coolant does not stay in the cylinder. A reduction effect can be expected. Further, since the cooling liquid does not stay in the cylinder, it is possible to avoid a situation in which when the cooling becomes necessary, the response is delayed due to the staying cooling liquid heated in the cylinder and knocking occurs.

According to a second aspect of the present invention, in the cooling structure for an internal combustion engine according to the first aspect, in the second coolant circulation system, coolant is circulated in parallel to the cylinder and the cylinder head by a second thermostat. In this case, most of the cooling liquid flows directly to the cylinder head, and the remaining cooling liquid flows to the cylinder.

When the coolant circulates in parallel to the cylinder and the cylinder head at a low temperature, the coolant flows mainly directly to the cylinder head and the coolant slightly flows to the cylinder, so that the temperature of the residual gas can be reduced more effectively. Can be suppressed.

According to a third aspect of the present invention, in the cooling structure for an internal combustion engine according to the first or second aspect, the valve operating temperature of the second thermostat is set higher than the valve operating temperature of the first thermostat. It is characterized by having.

At a low temperature, the coolant that does not pass through the radiator circulates in parallel through the cylinder head and the cylinder to suppress the temperature drop of the residual gas. When the temperature rises, first, the first thermostat operates to cause the coolant to pass through the radiator. The cylinder head and the cylinder are circulated in parallel to cool the cylinder head in particular, and when the temperature rises to a high temperature, the second thermostat operates to circulate the coolant from the cylinder to the cylinder head in series to cool the entire internal combustion engine I do.

According to a fourth aspect of the present invention, in the cooling structure for an internal combustion engine according to any one of the first to third aspects, the first thermostat and the second thermostat are provided with a circulating coolant. The temperature sensing part for detecting the temperature drives the valve element by expansion and contraction of the wax inside.

The wax provided inside the temperature sensing portion expands and contracts due to the temperature of the circulating coolant, and this change can use a conventional thermostat having a structure that opens and closes the valve body.
Cost reduction can be achieved.

According to a fifth aspect of the present invention, in the cooling structure for an internal combustion engine according to any one of the first to fourth aspects, the first thermostat includes a cooling liquid outlet of the radiator and an internal combustion engine. It is characterized in that it is disposed between.

By closing the coolant outlet side of the radiator with the first thermostat, a circulation path is formed only in the internal combustion engine without passing through the radiator. By opening the coolant outlet side of the radiator, the coolant passing through the radiator allows the coolant to pass through the internal combustion engine. Circulate institutions.

According to a sixth aspect of the present invention, in the cooling structure for an internal combustion engine according to any one of the first to fourth aspects, the first thermostat comprises a cooling liquid inlet of the radiator, It is characterized in that it is disposed between.

By closing the coolant inlet side of the radiator with the first thermostat, a circulation path is formed only in the internal combustion engine without passing through the radiator. By opening the coolant inlet side of the radiator, the coolant passing through the radiator allows the coolant to pass through the internal combustion engine. Circulate institutions.

According to a seventh aspect of the present invention, there is provided a first coolant circulation system including a first thermostat for adjusting a coolant circulation amount between a radiator and an internal combustion engine; A second coolant circulating system including a second thermostat for circulating the coolant in parallel with the head and controlling the coolant to circulate in series from the cylinder head to the cylinder when the temperature is higher than the predetermined coolant temperature. It is a cooling structure.

The second thermostat of the second coolant circulation system circulates the coolant in parallel with the cylinder and the cylinder head at a low temperature, and circulates the coolant from the cylinder head to the cylinder at a high temperature. Control and a drive device are unnecessary, the structure is simplified, and the cost can be reduced.

Further, since the cooling liquid always flows into the cylinder head first, the temperature of the liquid for cooling the cylinder head does not change even when the flow path is switched, and the cylinder head can be cooled more powerfully than before.

At a low temperature, the coolant is circulated directly to the cylinder head, and the coolant is also supplied to the cylinder, so that the coolant does not stay in the cylinder. A reduction effect can be expected. Further, since the cooling liquid does not stay in the cylinder, it is possible to avoid a situation in which when the cooling becomes necessary, the response is delayed due to the staying cooling liquid heated in the cylinder and knocking occurs. At a high temperature, all the coolant flows in series from the cylinder head to the cylinder, so that it is cooled strongly and the knocking level is prevented from deteriorating.

According to an eighth aspect of the present invention, in the cooling structure for an internal combustion engine according to the seventh aspect, the valve operating temperature of the second thermostat is set higher than the valve operating temperature of the first thermostat. Features.

At a low temperature, the coolant that does not pass through the radiator circulates in parallel through the cylinder head and the cylinder to suppress the temperature drop of the residual gas. When the temperature rises, first, the first thermostat operates to cause the coolant to pass through the radiator. The cylinder head and the cylinder are circulated in parallel to cool the cylinder head in particular, and when the temperature rises to a high temperature, the second thermostat operates to circulate the coolant from the cylinder head to the cylinder in series to cool the entire internal combustion engine I do.

According to a ninth aspect of the present invention, in the cooling structure for an internal combustion engine according to the seventh or eighth aspect, the first thermostat is disposed between a coolant outlet of the radiator and the internal combustion engine. It is characterized by that.

By closing the coolant outlet side of the radiator with the first thermostat, a circulation path is formed only in the internal combustion engine without passing through the radiator, and by opening the coolant outlet side of the radiator, the coolant passing through the radiator allows the coolant to pass through the internal combustion engine. Circulate institutions.

According to a tenth aspect of the present invention, in the cooling structure for an internal combustion engine according to the ninth aspect, the flow of the cooling liquid is branched, most of which is supplied to the cylinder head, and the remaining cooling liquid is supplied to the cylinder. A branching means, wherein the second thermostat is disposed between the coolant inlet of the radiator and the internal combustion engine, and when the temperature is lower than a predetermined temperature, the valve on the cylinder head side is opened to parallel the cylinder and the cylinder head. The coolant is circulated, and when the temperature is higher than a predetermined temperature, the valve on the cylinder head side is closed and the valve on the cylinder side is opened to circulate the coolant in series from the cylinder head to the cylinder.

When the first thermostat is at a temperature higher than the temperature at which the coolant outlet side of the radiator opens and lower than a predetermined temperature, the second thermostat opens the valve at the cylinder head side to cool the cylinder and the cylinder head in parallel. The coolant is circulated and the coolant is circulated directly to the cylinder head, and the coolant is also supplied to the cylinder.Therefore, the coolant does not stay in the cylinder. A reduction effect can be expected.
When the temperature is higher than the predetermined temperature, all the coolant flows in series from the cylinder head to the cylinder, so that the coolant is cooled strongly and the knocking level is prevented from deteriorating.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described below with reference to FIGS. 1 to 3 show a state of the cooling structure of the internal combustion engine 1 according to the present embodiment at a low temperature, FIGS. 4 to 6 show a state at a medium temperature, and FIGS. 7 to 7 show a state at a high temperature. It is shown in FIG.

The cooling structure will be described with reference to FIGS. Although the cylinder block 2 and the cylinder head 3 of the internal combustion engine 1 are shown separately, they are actually combined via a gasket, and a water jacket 2a around the cylinder bore of the cylinder block 2 is
The gasket hole communicates with the water jacket around the combustion chamber.

As shown in FIG. 2, the cylinder head 3 is provided with a water pump 4 and a first thermostat 5 adjacent to each other. The first thermostat 5 has an inlet port 5b, which is a temperature-sensitive part containing a wax and slides in the axial direction due to a temperature change, and communicates with a cooling water outlet 10b of the radiator 10 through a pipe 11. The intermittent connection with the outlet port 5d can be controlled, and the intermittent connection between the inlet port 5c and the outlet port 5d communicating with the cooling water outlet 3a of the water jacket of the cylinder head 3 via the bypass 7 and the connection pipe 6 can be controlled. .

In the first thermostat 5, when the temperature sensing part is sensitive to the temperature of the cooling water, and when the temperature is 80 ° C. or less, the valve body 5a closes the inlet port 5b communicating with the radiator 10 as shown in FIG. The inlet port 5c communicating with the bypass 7 is opened and communicates with the outlet port 5d. When the temperature exceeds 80 ° C., as shown in FIG. 5 (FIG. 8), the valve element 5a closes the inlet port 5c communicating with the bypass 7, opens the inlet port 5b communicating with the other radiator 10, and communicates with the outlet port 5d. .

The first thermostat 5 has a structure in which the wax provided inside the temperature sensing portion expands and contracts due to the temperature of the circulating cooling water, and this change has occurred before the opening and closing drive of the valve element. The cost can be reduced by using the thermostat.

The cooling water outlet 3a of the water jacket of the cylinder head 3 has a branched path, one of which is connected to the bypass 7, and the other of which is connected to the cooling water inlet 10a of the radiator 10 via a pipe 12 (FIG. 1). 1).

As shown in FIG. 2, the outlet port 5 d of the first thermostat 5 communicates with a pump suction port 4 a of the cooling water of the water pump 4. The pump outlet 4b of the water pump 4 communicates with the inlet port 20a of the second thermostat 20 via the pipe 13 (see FIG. 1).

The second thermostat 20 has a large-diameter cylindrical body 21 having a temperature-sensitive portion 21a filled with wax at the center thereof, which is slidably supported by holders 24 and 25.
A disk-shaped first valve body 22 and a second valve body 23 are integrally fitted on both sides with a in between, and a conventional thermostat is used.

A hollow disk-shaped valve seat of a holder 24 in contact with the first valve body 22 partitions the inside of the case of the second thermostat 20 between the main body side and the outlet port 20b side, while the second valve body 23 is no longer provided. Open / close the opening of one outlet port 20c.

The outlet port 20b communicates with the water jacket 2a of the cylinder block 2 via the pipe 14, and the other outlet port 20c communicates directly with the water jacket of the cylinder head 3 via the pipe 15. .

In the second thermostat 20, when the temperature sensing part 21a is sensitive to the temperature of the cooling water and the temperature is below 100 ° C., the first valve body 22 closes the outlet port 20b as shown in FIG. A body 23 opens the outlet port 20c and communicates with the inlet port 20a. When the temperature exceeds 100 ° C., as shown in FIG.
Closes the outlet port 20c, and the first valve body 22 closes the outlet port 20b.
To communicate with the inlet port 20a.

The second thermostat 20 is provided with a through hole 27 which also serves as an air vent at the periphery of the valve seat of the holder 24 which separates the inside of the case from the main body side and the outlet port 20b side. The 20a side and the outlet port 20b side are always in communication.

The internal combustion engine 1 has the above-described cooling structure, and how the flow path of the cooling water changes according to the temperature of the cooling water will be described with reference to FIGS.

First, in a low-temperature operation state in which the cooling water temperature is 80 ° C. or lower, as shown in FIGS. 1 to 3, the first thermostat 5 closes the inlet port 5b where the valve element 5a communicates with the radiator 10, and The inlet port 5c communicating with the bypass 7 is opened and communicated with the outlet port 5d, so that the reflux cooling water from the cylinder head 3 passes through the bypass 7 without circulating through the radiator 10, and the inlet port 5 of the first thermostat 5 does not.
c, is sucked into the water pump 4 from the outlet port 5d, and is discharged from the pump discharge port 4b to the second thermostat 20 via the pipe 13.

In the second thermostat 20, the first valve body 22 closes the outlet port 20b, and at the same time, the second valve body 23 closes the outlet port 20b.
c, which communicates with the inlet port 20a, so that the cooling water discharged from the water pump 4 enters the inlet port 20a of the second thermostat 20 and directly from the outlet port 20c to the water jacket of the cylinder head 3 via the pipe 15. Inflow.

On the other hand, the inlet port 20 of the second thermostat 20
Part of the cooling water that has entered a flows into the water jacket 2a of the cylinder block 2 from the outlet port 20b through the pipe 14 through the through hole 27 of the holder 24, and circulates through the water jacket of the cylinder head 3.

FIG. 3 is a block diagram showing the flow of the cooling water in the operating state where the cooling water temperature is 80 ° C. or lower as described above. That is, the cooling water discharged from the water pump 4 flows from the second thermostat 20 to the cylinder head 3 and the cylinder block 2 in parallel, and most of the cooling water flows directly to the cylinder head 3 (thick solid line in FIGS. 1 and 3). Arrows), and the remainder of the cooling water flows to the cylinder block 2 and then to the cylinder head 3 via the cylinder block 2 (the thin solid line arrow in FIGS. 1 and 3).

The cooling water collected in the cylinder head 3 passes through the bypass 7 without passing through the radiator 10 from the cylinder head 3.
Circulates through the first thermostat 5 to the water pump 4 to suppress a decrease in the temperature of the residual gas in the combustion chamber.

At a low temperature, the coolant is circulated directly to the cylinder head 3, and at least a small amount of coolant flows through the cylinder block 2, so that the coolant does not stay in the cylinder block 2, and the residual gas in the combustion chamber remains. Can be suppressed more effectively.

Next, when the temperature of the cooling water is higher than 80 ° C. and lower than 100 ° C., as shown in FIGS. 4 to 6, the first thermostat 5 is operated by opening the valve body 5a so as to communicate with the bypass 7. The port 5c is closed, the inlet port 5b communicating with the radiator 10 is opened, and the reflux cooling water from the cylinder head 3 flows to the radiator 10 (see FIG. 5).

On the other hand, in the second thermostat 20, the first valve body 22 closes the outlet port 20b and the second
The valve element 23 opens the outlet port 20c and communicates with the inlet port 20a so that most of the cooling water flows directly to the cylinder head 3 (thick solid line arrows in FIGS. 4 and 6), and the rest of the cooling water flows to the cylinder block 2. (Thin solid arrows in FIGS. 4 and 6).

Therefore, most of the cooling water circulated through the radiator 10 and deprived of heat and having a low temperature flows directly to the cylinder head 3 to actively cool the combustion chamber. Also, a part of the cooling water flows through the cylinder block 2 to the cylinder head 3 through the through hole 27 in the cylinder block 2, so that the cooling water does not stay in the cylinder block 2.

Therefore, when the cylinder head 3 is to be cooled, the high-temperature cooling water that has stayed in the cylinder block 2 as in the prior art flows into the cylinder head 3 to hinder the cooling of the cylinder head 3 and cause knocking or the like. Can be avoided.

When the temperature of the cooling water further exceeds 100 ° C., as shown in FIGS.
, The valve body 5a closes the inlet port 5c and opens the inlet port 5b communicating with the radiator 10 (see FIG. 8).
Flow to 10. On the other hand, the second thermostat 20 operates to cause the first valve body 22 to open the outlet port 20b and the second valve body 23 to close the outlet port 20c as shown in FIG.

Therefore, as shown in FIG. 9, the cooling water discharged from the water pump 4 is supplied to the second thermostat 20, the cylinder block 2, the cylinder head 3, the radiator 10,
A circulation path which flows through the first thermostat 5 in order and returns to the water pump 4 is formed. The cooling water flowing through the radiator 10 flows from the second thermostat 20 to the cylinder block 2 and the cylinder head 3 in series, and a large amount of cooling water also flows to the cylinder block 2 to actively cool the entire internal combustion engine 1. .

As described above, the flow of the cooling water is controlled by the two thermostats 5, 20. In particular, the flow of the cooling water to the cylinder block 2 and the cylinder head 3 is controlled by the second thermostat 20. This eliminates the need for control by a control unit and a driving device, simplifies the structure, and reduces costs.

In the above embodiment, the first thermostat 5 is provided at the cooling water outlet 10b of the radiator 10 via the pipe 11 and is connected to the internal combustion engine 1. However, the first thermostat 5 is provided at the cooling water inlet side of the radiator. FIG. 1 is a block diagram of the cooling structure according to the embodiment in different temperature states.
0 to FIG. 12 will be described.

The main members other than the first thermostat 30 are as follows.
Since it is the same as the above embodiment, the same reference numeral is used. The first thermostat 30 has an outlet port connected to the cooling water inlet of the radiator 10, another outlet port connected to the pump suction port of the water pump 4, and an inlet port connected to the cooling water outlet of the water jacket of the cylinder head 3. Are linked.

In a low-temperature operation state in which the cooling water temperature is 80 ° C. or less, the outlet port communicating with the radiator 10 is closed and the outlet port connected to the pump suction port of the water pump 4 is opened as shown in FIG.

The reflux cooling water from the cylinder head 3 is
The water enters the inlet port of the thermostat 30, is drawn into the water pump 4 from the outlet port without circulating through the radiator 10, and is discharged from the pump discharge port 4b to the second thermostat 20.

In the second thermostat 20, the first valve body 22 closes the outlet port 20b, and at the same time, the second valve body 23 closes the outlet port 20b.
c, which communicates with the inlet port 20a, so that the cooling water discharged from the water pump 4 enters the inlet port 20a of the second thermostat 20 and directly from the outlet port 20c to the water jacket of the cylinder head 3 via the pipe 15. As it flows in (indicated by the thick solid line arrow in FIG. 10), part of the cooling water entering the inlet port 20a is
27, flows into the water jacket 2a of the cylinder block 2 from the outlet port 20b via the pipe 14 (FIG. 1).
0 (a thin solid line arrow), and circulates through the water jacket of the cylinder head 3.

Therefore, the cooling water collected in the cylinder head 3 is circulated to the water pump 4 without passing through the radiator 10 via the first thermostat 5 and can suppress a decrease in the temperature of the residual gas in the combustion chamber.

At a low temperature, the coolant is circulated directly to the cylinder head 3, and at least a small amount of coolant flows through the cylinder block 2, so that the coolant does not stay in the cylinder block 2, and the residual gas in the combustion chamber is reduced. Can be suppressed more effectively.

Next, when the cooling water temperature exceeds 80 ° C. and is 100 ° C. or less, as shown in FIG.
Closes the inlet port communicating with the water pump 4, opens the outlet port 5b communicating with the radiator 10, and allows the reflux cooling water from the cylinder head 3 to flow to the radiator 10.

Therefore, most of the cooling water circulated through the radiator 10 and deprived of heat and having a low temperature flows directly to the cylinder head 3 (thick solid line arrow in FIG. 11) to actively cool the combustion chamber. Then, a part of the cooling water flows from the through hole 27 to the cylinder head 3 through the cylinder block 2 to the cylinder head 3 (the thin solid arrow in FIG. 11).
There is no stagnation of cooling water.

When the temperature of the cooling water further exceeds 100 ° C., as shown in FIG.
Opens the outlet port 20b, and the second valve body 23 opens the outlet port 20c.
The cooling water flowing through the radiator 10 is closed from the second thermostat 20 to the cylinder block 2 as shown in FIG.
A large amount of cooling water flows in the cylinder head 3 in series with the cylinder head 3, and the entire internal combustion engine 1 can be actively cooled.

Next, a cooling structure for an internal combustion engine according to another embodiment will be described. 13 to 15 are block diagrams of the cooling structure in three temperature states. This embodiment is different from the embodiment shown in FIGS. 1 to 9 in that the second thermostat and the arrangement thereof are different, and the joint of the second thermostat 20 is provided at the place of the second thermostat 20.
Are provided, and the others are the same. The reference numerals of the other main members are the same as those of the above embodiment.

Therefore, the first thermostat 5 is provided at the cooling water outlet of the radiator 10, and can switch the flow of the cooling water between the cylinder head 3 side and the radiator 10 side at a boundary of 80 ° C. The joint 41 supplies the cooling water discharged from the water pump 4 to most of the cylinder head 3 and partially connects the cylinder block 2 through the orifice.
To supply it.

The second thermostat 40 has an outlet port communicating with the cooling water inlet of the radiator 10, one of the two inlet ports communicating with the water jacket of the cylinder head 3, and the other communicating with the water jacket of the cylinder block 2. ing. And, at 100 ° C, the communication between the two inlet ports is interrupted.

That is, in the low-temperature operation state in which the cooling water temperature is 80 ° C. or lower, as shown in FIG. 13, the second thermostat 40 is in a state where the inlet port on the cylinder head 3 side is open and the inlet port on the cylinder block 2 side is closed. The first thermostat 5 opens the inlet port on the cylinder head 3 side and closes the radiator 10 side.

Since the radiator 10 side of the first thermostat 5 is closed, there is no flow of cooling water to the radiator 10 via the second thermostat 40, and the reflux cooling water from the cylinder head 3 circulates through the radiator 10. Without passing through the bypass 7, the gas enters the inlet port 5c of the first thermostat 5 through the bypass port 7, is drawn into the water pump 4 from the outlet port 5d, and is mainly transferred from the pump discharge port 4b to the cylinder head 3 via the joint 41 (FIG. 13). , A part of the cylinder block 2 (a thin solid arrow in FIG. 13).

Therefore, it is possible to suppress a decrease in the temperature of the residual gas in the combustion chamber, to circulate the coolant directly to the cylinder head 3 at a low temperature,
Since even a small amount of cooling water flows, the cooling water does not stay in the cylinder block 2 and the temperature drop of the residual gas in the combustion chamber can be more effectively suppressed.

When the cooling water temperature exceeds 80 ° C. and is equal to or lower than 100 ° C., the first thermostat 5 closes the inlet port on the cylinder head 3 side and opens the radiator 10 side as shown in FIG. The cooling water collected in 3 is the second
It flows in from the open inlet port of the thermostat 40, flows to the radiator 10 from the outlet port, is cooled and flows into the first thermostat 5, and is connected from the water pump 4 to the joint.
Through the cylinder 41, the air mainly flows in parallel to the cylinder head 3 (thick solid line arrow in FIG. 14) and partially to the cylinder block 2 (thin solid line arrow in FIG. 14).

Therefore, most of the cooling water circulated through the radiator 10 and deprived of heat and having a low temperature flows directly to the cylinder head 3 (thick solid line arrow in FIG. 14) to actively cool the combustion chamber. Also, a part of the cooling water flows from the orifice to the cylinder head 3 via the cylinder block 2 (arrows in thin solid lines in FIG. 14), so that the cooling water does not stay in the cylinder block 2.

Therefore, when the cylinder head 3 is to be cooled, the high-temperature cooling water that has stayed in the cylinder block 2 as in the prior art flows into the cylinder head 3 to hinder the cooling of the cylinder head 3 and cause knocking or the like. Can be avoided.

When the cooling water temperature further exceeds 100 ° C., the second thermostat 40 closes the inlet port on the cylinder head 3 side and opens the inlet port on the cylinder block 2 side as shown in FIG. Cooling water
Most of the flow from the joint 41 to the cylinder head 3, flows directly to the cylinder block 2 as it is, flows directly to the cylinder block 2 through an orifice, and the two flows gather in the water jacket of the cylinder block 2 to form a second thermostat. It flows to 40 and further circulates to the radiator 10.

A large amount of cooling water flows into the cylinder block 2 together with the cylinder head 3 to actively cool the entire internal combustion engine 1 and prevent the knocking level from deteriorating. Since the cooling water always flows into the cylinder head 3 first, the temperature of the liquid for cooling the cylinder head 3 does not change even when the flow path is switched, and the cylinder head can be cooled more powerfully than before.

As described above, the flow of the cooling water is controlled by the two thermostats 5 and 40. In particular, the flow of the cooling water of the cylinder block 2 and the cylinder head 3 is controlled by the second thermostat 40. This eliminates the need for control by a control unit and a drive device, simplifies the structure, and reduces costs.

Next, a cooling structure for an internal combustion engine according to still another embodiment will be described. FIG. 16 to FIG.
It is a block diagram of three temperature states of the cooling structure. This embodiment has basically the same configuration as the embodiment shown in FIG. 13 to FIG. 15, except that the first thermostat 50 is provided at the cooling water inlet of the radiator. . The reference numerals of the same main members are the same as those of the above embodiment.

The first radiator is provided with a cooling water inlet.
The thermostat 50 has a valve at an inlet port connected to the cylinder head 3 and the second thermostat 40, and a valve at an outlet port connected to the radiator 10 and the water pump 4, respectively. Open and close at ℃.

The second thermostat 40 has a valve at an inlet port connected to each of the water jackets of the cylinder head 3 and the cylinder block 2, and opens and closes at 100 ° C.

In a low-temperature operation state in which the cooling water temperature is 80 ° C. or lower, as shown in FIG. 16, the second thermostat 40 opens the inlet port on the cylinder head 3 side and closes the inlet port on the cylinder block 2 side. Then, the first thermostat 50 opens the inlet port on the cylinder head 3 side,
The inlet port on the second thermostat 40 side is closed, the outlet port on the radiator 10 is closed, and the outlet port on the water pump 4 is opened.

The cooling water returned from the cylinder head 3 is
The water is sucked into the water pump 4 without circulating through the radiator 10 via the thermostat 50, and is mainly transferred from the pump discharge port 4b to the cylinder head 3 via the joint 41 (thick solid line arrow in FIG. 16). (Arrows in FIG. 16).

Therefore, it is possible to suppress a decrease in the temperature of the residual gas in the combustion chamber, and to prevent the cooling water from remaining in the cylinder block 2, thereby more effectively suppressing the decrease in the temperature of the residual gas in the combustion chamber. it can.

When the cooling water temperature is higher than 80 ° C. and lower than 100 ° C., the first thermostat 50 closes the inlet port on the cylinder head 3 side and the outlet port on the water pump 4 as shown in FIG. Since the inlet port on the thermostat 40 side and the outlet port on the radiator 10 side are opened, the cooling water collected in the cylinder head 3 flows in from the open inlet port of the second thermostat 40, and from the outlet port via the first thermostat 50 through the radiator. 10, cooled and drawn into the water pump 4, and mainly through the joint 41 to the cylinder head 3 (thick solid line arrow in FIG. 17) and partially to the cylinder block 2 (thin solid line arrow in FIG. 17). Flows.

Therefore, most of the cooling water circulated through the radiator 10 and deprived of heat and having a low temperature flows directly to the cylinder head 3 (thick solid line arrow in FIG. 17), and actively cools the combustion chamber. Also, a part of the cooling water flows from the orifice to the cylinder head 3 through the cylinder block 2 to the cylinder head 3 (arrows shown by thin solid lines in FIG. 17), so that the cooling water does not stay in the cylinder block 2.

Therefore, when the cylinder head 3 is to be cooled, the high-temperature cooling water that has stayed in the cylinder block 2 as in the prior art flows into the cylinder head 3 so as to hinder the cooling of the cylinder head 3 and cause knocking or the like. Can be avoided.

If the temperature of the cooling water further exceeds 100 ° C., the second thermostat 40 closes the inlet port on the cylinder head 3 side and opens the inlet port on the cylinder block 2 side as shown in FIG. Cooling water
Most of the flow from the joint 41 to the cylinder head 3, flows directly to the cylinder block 2 as it is, flows directly to the cylinder block 2 through an orifice, and the two flows gather in the water jacket of the cylinder block 2 to form a second thermostat. Flow to 40, and the first thermostat
Circulating to radiator 10 via 50.

A large amount of cooling water flows into the cylinder block 2 together with the cylinder head 3 to actively cool the entire internal combustion engine 1 and prevent the knocking level from deteriorating. Since the cooling water always flows into the cylinder head 3 first, the temperature of the liquid for cooling the cylinder head 3 does not change even when the flow path is switched, and the cylinder head can be cooled more powerfully than before.

As described above, the flow of the cooling water is controlled by the two thermostats 40 and 50, and the control by the control unit and the driving device are not required, and the structure is simplified.
Cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state where a cooling water temperature in a cooling structure of an internal combustion engine is low.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a block diagram showing a flow of the cooling water.

FIG. 4 is a cross-sectional view illustrating a state in which the cooling water temperature in the cooling structure of the internal combustion engine is an intermediate temperature.

FIG. 5 is a sectional view taken along the line VV in FIG. 4;

FIG. 6 is a block diagram showing a flow of the cooling water.

FIG. 7 is a cross-sectional view illustrating a state in which the cooling water temperature in the cooling structure of the internal combustion engine is high.

FIG. 8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a block diagram showing a flow of the cooling water.

FIG. 10 is a block diagram showing a flow of cooling water in a state where the cooling water temperature is low in the cooling structure of the internal combustion engine according to another embodiment.

FIG. 11 is a block diagram showing a flow of the cooling water in a state where the cooling water temperature in the cooling structure of the internal combustion engine is an intermediate temperature.

FIG. 12 is a block diagram showing a flow of the cooling water in a state where the temperature of the cooling water is high in the cooling structure of the internal combustion engine.

FIG. 13 is a block diagram showing a flow of cooling water in a state where the cooling water temperature is low in the cooling structure of the internal combustion engine according to another embodiment.

FIG. 14 is a block diagram showing a flow of the cooling water in a state where the cooling water temperature in the cooling structure of the internal combustion engine is an intermediate temperature.

FIG. 15 is a block diagram showing a flow of cooling water in a state where the cooling water temperature is high in the cooling structure of the internal combustion engine.

FIG. 16 is a block diagram showing a flow of cooling water in a state where the temperature of the cooling water is low in the cooling structure of the internal combustion engine according to still another embodiment.

FIG. 17 is a block diagram showing a flow of cooling water in a state where the cooling water temperature in the cooling structure of the internal combustion engine is an intermediate temperature.

FIG. 18 is a block diagram showing a flow of cooling water in a state where the temperature of the cooling water is high in the cooling structure of the internal combustion engine.

FIG. 19 is a block diagram showing a flow of a conventional cooling liquid.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Cylinder block, 3 ... Cylinder head, 4 ... Water pump, 5 ... 1st thermostat,
6 connection pipe, 7 bypass, 10 radiator, 11, 12,
13, 14, 15 ... pipe, 20 ... second thermostat, 21 ... cylindrical body, 22 ... first valve body, 23 ... second valve body, 24, 25 ... holder, 27 ... through hole, 30 ... first thermostat, 40 ... second thermostat, 41 ... joint, 50 ... first thermostat.

Claims (10)

[Claims] 1. A first coolant circulation system having a first thermostat for adjusting a coolant circulation amount between a radiator and an internal combustion engine, and a coolant in parallel with a cylinder and a cylinder head when the coolant temperature is lower than a predetermined coolant temperature. And a second thermostat for controlling the coolant to circulate in series from the cylinder to the cylinder head when the coolant temperature is higher than the predetermined coolant temperature.
A cooling structure for an internal combustion engine, comprising: a cooling liquid circulation system. 2. In the second coolant circulation system, when coolant is circulated in parallel to a cylinder and a cylinder head by a second thermostat, most of the coolant flows directly to the cylinder head, and the remaining coolant remains in the cylinder. The cooling structure for an internal combustion engine according to claim 1, wherein the cooling fluid flows. 3. The cooling structure for an internal combustion engine according to claim 1, wherein the valve operating temperature of the second thermostat is set higher than the valve operating temperature of the first thermostat. 4. The first thermostat and the second thermostat.
The thermostat according to any one of claims 1 to 3, wherein the temperature sensing part for detecting the temperature of the circulating coolant drives the valve body by expansion and contraction of the wax inside the thermostat. A cooling structure for an internal combustion engine according to the above. 5. The internal combustion engine according to claim 1, wherein the first thermostat is disposed between a coolant outlet of the radiator and an internal combustion engine. Engine cooling structure. 6. The internal combustion engine according to claim 1, wherein the first thermostat is disposed between a coolant inlet of the radiator and an internal combustion engine. Engine cooling structure. 7. A first coolant circulation system including a first thermostat for adjusting a coolant circulation amount between a radiator and an internal combustion engine; A second thermostat for controlling the coolant to circulate in series from the cylinder head to the cylinder when the coolant temperature is higher than the predetermined coolant temperature.
A cooling structure for an internal combustion engine, comprising: a cooling liquid circulation system. 8. The cooling structure for an internal combustion engine according to claim 7, wherein a valve operating temperature of said second thermostat is set higher than a valve operating temperature of said first thermostat. 9. The cooling structure for an internal combustion engine according to claim 7, wherein the first thermostat is disposed between a coolant outlet of the radiator and the internal combustion engine. 10. A branching means for branching a flow of a coolant and supplying most of the coolant to the cylinder head and supplying the remaining coolant to the cylinder, wherein the second thermostat is provided with a coolant inlet of the radiator. When the temperature is lower than a predetermined temperature, the valve on the cylinder head side is opened to circulate the coolant in parallel with the cylinder and the cylinder head, and when the temperature is higher than the predetermined temperature, the valve on the cylinder head side is closed. 10. The cooling structure for an internal combustion engine according to claim 9, wherein the coolant is circulated in series from the cylinder head to the cylinder by opening a valve on the cylinder side.