WO2013080980A1

WO2013080980A1 - Engine cooling apparatus and engine cooling method

Info

Publication number: WO2013080980A1
Application number: PCT/JP2012/080646
Authority: WO
Inventors: 祟金田; 純平稲葉
Original assignee: カルソニックカンセイ株式会社; 東京ラヂエーター製造株式会社
Priority date: 2011-11-28
Filing date: 2012-11-27
Publication date: 2013-06-06
Also published as: CN103987935A; JP2013113182A; EP2787189A1; EP2787189A4; US20140326198A1

Abstract

The present invention relates to an engine cooling apparatus which comprises an EGR system or the like, and an engine cooling method. Provided are the engine cooling apparatus and the engine cooling method which are capable of reducing the capacity of a main radiator, saving costs, and effectively using a mounting space by providing a sub-radiator having an auxiliary function for the main radiator. A sub-control valve (22) is disposed to split and send a portion of a coolant sent to a main radiator (16) to a sub-circuit when a temperature of the coolant is higher than an upper limit of the temperature of the coolant in a normal engine state, as the result of detecting the temperature of the coolant in a main circuit. The coolant sent by the sub-control valve (22) to the sub-circuit (12) is cooled by a sub-radiator (28) and introduced into a cooler device, and the coolant at the sub-circuit (12) is split to be returned to an upper stream portion of a first pump (18) of the main circuit (8).

Description

Engine cooling device and cooling method thereof

The present invention relates to an engine cooling apparatus having an EGR system or the like and a cooling method thereof.

Conventionally, EGR systems (exhaust gas recirculation mechanisms) that recirculate exhaust gas to the engine have been widely adopted as a countermeasure against air pollution by exhaust gas in vehicles equipped with diesel engines.

In the above diesel engine, if hot exhaust gas is recirculated to the intake air of the engine as it is, SOOT (soot) is generated and fuel consumption increases. As a means for solving these problems, an EGR cooler (heat exchanger) is generally provided, and the exhaust gas is cooled by cooling water and then returned to the engine. Most of the cooling water used in the EGR cooler is cooling water that also serves as engine cooling.

In the main cooling water circuit that cools the engine, the cooling water radiated from the radiator by the running wind is returned to the engine, but a part is led out and allowed to flow into the EGR cooler before the engine is cooled. This cooling water cools the EGR gas (exhaust gas) with the EGR cooler, and then merges with the cooling water flowing into the engine from the radiator. Further, a part of the cooling water flows again into the EGR cooler, and the remaining cooling water The engine is cooled to form a flow path that circulates to the radiator overnight.

Although it depends on the driving conditions of the vehicle, the temperature of the cooling water after the heat is generally dissipated by the radiator is generally over 80 ° C. while the engine is running. For this reason, the exhaust gas cooled by the EGR cooler with the cooling water does not fall below the cooling water temperature.

In recent years, in order to tighten regulations on exhaust gas, measures such as increasing the capacity of the EGR cooler and lowering the combustion temperature of the engine are required. Among these, increasing the capacity of the EGR cooler has been dealt with by increasing the size of the EGR cooler or increasing the number of EGR coolers to be used. Further, in order to lower the combustion temperature of the engine, it is necessary to lower the temperature of the exhaust gas (EGR gas) that returns to the engine.

As a conventional technique, for example, Patent Document 1 describes a cooling device for EGR gas shown in FIG. This includes a water pump 53 disposed in the cooling water passage 52 of the engine 51, an EGR cooler 57 disposed in the branch circulation passage 56 branched from the downstream cooling water passage, and the downstream thereof. An EGR radiator 59 or the like is provided to reduce the dependency of the EGR gas temperature on the engine coolant temperature.

Patent Document 2 describes an EGR device in which an EGR radiator independent from an engine cooling system is provided, and the EGR cooler is thermally coupled to increase the cooling capacity of the EGR cooler.
Patent Document 3 discloses a high temperature first cooling loop in which an internal combustion engine, a heat exchanger, and the like are incorporated, a cooling unit (intercooler), and a low temperature for the purpose of shortening the warm-up time of an internal combustion engine of an automobile such as a truck. A cooling system for a supercharged internal combustion engine having a low temperature second cooling loop in which a heat exchanger or the like is incorporated is disclosed.

Japanese Unexamined Patent Publication No. 2006-132469 Japanese Unexamined Patent Publication No. 2003-278608 US Patent Application Publication No. 2008/0066697

Now, when the vehicle speed is low, such as running uphill, the engine coolant becomes hot during high-load operation. This is because when the vehicle speed is slowed down, the wind speed corresponding to the radiator falls and the cooling efficiency falls. Moreover, it is also because the load of an engine becomes high by climbing and the amount of heat generated by the engine increases.

For this reason, in the past, the heat dissipation performance of the radiator was set assuming the above maximum load. However, in the low / medium load operation that occupies most of the vehicle operation time, the actual situation is that only a part of the capability of the radiator is used.

When the radiator was designed for the high load operation of the engine, there was a problem that a large size radiator had to be made. The same applies to the conventional techniques according to Patent Documents 1 to 3. If only low / medium load operation needs to be considered, the radiator can be made smaller.

The present invention has been made to solve the above-described problems. By providing the sub-radiator with a function of assisting the main radiator, the capacity of the main radiator can be reduced, the cost can be reduced, and the mounting space can be effectively used. It is an object of the present invention to provide an engine cooling device and a cooling method thereof.

In order to solve the above technical problems, an engine cooling apparatus according to the present invention includes a main radiator that cools cooling water flowing through the engine, and a main circuit of cooling water that circulates between the engine and the main radiator. Cooling the cooling water that is provided on the upstream side of the engine of the main circuit and that is used in a cooler device that cools the heating element mounted on the vehicle independently of the main circuit and the first pump that circulates and drives the cooling water. A sub-radiator, a sub-circuit for cooling water circulating through the cooler device and the sub-radiator, a second pump provided in the middle of the sub-circuit for driving the cooling water in the sub-circuit, and the main circuit Cooling water sent to the main radiator when this temperature exceeds the upper limit value of the cooling water temperature during steady operation of the engine A sub-control valve that diverts a part of the sub-circuit and sends the sub-control valve to the sub circuit. Cooling water sent to the sub circuit by the sub-control valve is cooled by the sub-radiator and flows into the cooler device. In addition, the cooling water of the sub circuit is diverted and returned to the upstream side of the first pump of the main circuit.

The engine cooling device according to the present invention detects the temperature of the cooling water in the main circuit, and passes through the engine when the temperature does not reach the lower limit value of the temperature of the cooling water in the steady state of the engine. Main control that returns the cooling water to the engine and warms up the engine, and when the temperature is equal to or higher than the lower limit value, sends a part or all of the cooling water that has passed through the engine toward the main radiator of the main circuit It is the structure which provided the valve.

The engine cooling device according to the present invention has a configuration in which the lower limit value of the temperature of the cooling water at the time of steady operation of the engine is 80 ° C. and the upper limit value is 100 ° C.

In the engine cooling device according to the present invention, the lower limit value of the temperature of the cooling water in the steady state of the engine is any value in the range of 70 ° C to 90 ° C, and the upper limit value is any value in the range of 90 ° C to 120 ° C. It is the structure made into the value of.
In this case, the lower limit value can be set to, for example, 70 ° C. or 85 ° C. within the above range, and the upper limit value can also be set to, for example, 95 ° C. or 120 ° C.

In addition, the engine cooling device according to the present invention has a configuration in which a bypass circuit is provided that sends the cooling water divided by the sub control valve to the upstream or downstream sub circuit of the second pump.
The engine cooling device according to the present invention has a configuration in which an EGR cooler is provided in a lead-out circulation circuit that divides cooling water from the main circuit.
The engine cooling apparatus according to the present invention has an EGR cooler provided in the middle of the sub-circuit.

An engine cooling method according to the present invention uses any one of the engine cooling apparatuses described above, sends a part of the cooling water of the main circuit to the sub circuit, and cools the cooling water with the sub radiator. It is to return to the upstream side of the engine of the main circuit again.

According to the engine cooling apparatus of the present invention, the cooling water sent to the sub circuit by the sub control valve is cooled by the sub radiator and flows into the cooler device, and the cooling water of the sub circuit is divided and the main circuit Because the main pump is configured to return to the upstream side of the first pump, the main radiator can be set to a size that matches the low / medium-load operation, and a main radiator that is smaller than before can be configured. Therefore, the main radiator can be prevented from being enlarged, and the cost can be reduced and the radiator can be effectively used.

According to the engine cooling method of the present invention, a part of the cooling water of the main circuit is sent to the sub-circuit using the engine cooling device, the cooling water is cooled by the sub-radiator, and again the upstream of the engine of the main circuit. Therefore, the main radiator can be set to a size suitable for low / medium-load operation, avoiding an increase in the size of the main radiator, reducing costs, and making effective use of the radiator's mounting space It also has the effect of contributing.

1 is a block diagram illustrating a configuration of an engine cooling device according to a first embodiment. FIG. It is a block diagram which shows the distribution | circulation form of the cooling water in a subcircuit (and a part of main circuit) concerning embodiment. It is a block diagram which shows the structure of the cooling device of the engine which concerns on other embodiment. It is a block diagram which concerns on 2nd embodiment and shows the structure of the cooling device of an engine. FIG. 10 is a block diagram illustrating a configuration of an engine cooling device according to a third embodiment. It is a figure which shows the cooling device of EGR gas which concerns on a prior art example.

Hereinafter, an embodiment of the present invention with reference to the accompanying drawings.
In this embodiment, the engine cooling device 2 and the engine cooling method are applied to a vehicle equipped with an engine 4 (here, a diesel engine) that supports exhaust gas regulation with a large-capacity EGR mechanism or the like, such as a truck.
FIG. 1 is a block diagram showing a configuration of an engine cooling device 2 according to the first embodiment.

The engine cooling device 2 includes a main circuit 8 for cooling water that cools the engine 4 and the first EGR cooler 6 using the main radiator 16, and a second cooling water that uses the sub radiator 28 to cool the second water. The sub-circuit 12 that cools the EGR cooler 10 is provided.
Further, the sub-circuit 12 is provided with a branching portion 14, and cooling water flowing through the sub-circuit 12 flows into the main circuit 8 from the branching portion 14 under a predetermined condition, flows through the engine 4 and again flows into the main circuit 8. To the sub-circuit 12.

The main circuit 8 is provided with an engine 4, a main radiator 16, a first pump 18, a main control valve 20, a sub control valve 22, and a first EGR cooler 6. The sub circuit 12 is provided with a sub radiator 28, a second EGR cooler 10, and a second pump 30. The cooling device 2 is provided with an intercooler 38.

In the main circuit 8, the cooling water from the main radiator 16 flows into the engine 4 via the first pump 18 and returns to the main radiator 16 again, and a part of the cooling water is derived from the engine 4. In addition, a lead-out circulation circuit 9 is formed which flows into the first EGR cooler 6 and returns to the engine 4 again. As the lead-out circulation circuit 9, a circuit in which cooling water is derived from the main circuit 8 other than the engine 4, flows into the first EGR cooler 6, and is returned to the main circuit 8 again is possible.

Also, the main circuit 8 is provided with a first bypass circuit 27 for circulating cooling water from the main control valve 20 to the first pump 18. Further, the main circuit 8 is provided with a second bypass circuit 31 for circulating cooling water from the sub control valve 22 to the second pump 30.

In the sub-circuit 12, a circulation circuit is formed in which the cooling water from the sub-radiator 28 flows into the second EGR cooler 10 and is returned to the sub-radiator 28 again via the second pump 30.
In the second EGR cooler 10, the exhaust gas (EGR gas) cooled by the first EGR cooler 6 is further cooled to a low temperature, so that the cooling at a lower temperature than the cooling water cooled by the main radiator 16 is performed. Water is needed.

The main radiator 16 mainly cools the cooling water for the engine 4, and the sub radiator 28 mainly cools the cooling water used for the cooler equipment such as the second EGR cooler 10 and the intercooler 38.
The first EGR cooler 6 and the second EGR cooler 10 both cool the exhaust gas (EGR gas). The intercooler 38 cools the supercharged air.

Each of the first pump 18 and the second pump 30 provided in each circuit is a water pump, and drives the cooling water to circulate in the circuit. As the first pump 18 and the second pump 30, a mechanical pump using the driving force of the engine 4 or an electric pump is used. In this case, a mechanical pump is used as the first pump 18, and the same mechanical pump as the first pump 18 is used as the second pump 30, or an electric pump is used only for the second pump 30. You can also. The electric pump is electrically controlled and can be easily controlled from an ECU or the like.
Each of the first pump 18 and the second pump 30 is provided with one inlet for cooling water (however, the first pump 18 is provided with an inlet for cooling water from two circuits) and has one outlet. It is a thing.

The first pump 18 is provided in the main circuit 8 (upstream side of the engine 4) between the main radiator 16 and the engine 4, and drives the coolant output from the main radiator 16 toward the engine 4, Cooling water in the main circuit 8 is circulated. The second pump 30 is provided in the sub circuit 12 (on the downstream side of the second EGR cooler 10) between the second EGR cooler 10 and the sub radiator 28, and the cooling water of the sub circuit 12 is supplied to the sub radiator 28. The cooling water in the sub-circuit 12 is circulated.

The main control valve 20 and the sub control valve 22 are all three-way valves (two inlet and outlet ports), both of which are so-called thermostats that detect the temperature of the cooling water and open and close (divide) the cooling water channel. It is.
The main control valve 20 opens and closes the valve based on the temperature of the cooling water, for example, 85 ° C. (cooling during steady engine operation, the lower limit value of the water temperature). The sub control valve 22 opens and closes the valve on the basis of a temperature higher than that of the main control valve 20, for example, 95 ° C. (the upper limit value of the cooling water temperature when the engine is stationary). The main control valve 20 can be fully opened and fully closed (and intermediately opened), and the sub control valve 22 may not be fully closed (flow to the main circuit 8 is ensured).

The main control valve 20 is provided in the main circuit 8 at a position where the coolant has passed through the engine 4 (on the downstream side of the engine 4). This main control valve 20 detects the temperature of the cooling water in the vicinity of the main circuit 8 to open and close the valve, and allows the cooling water that has passed through the engine 4 to flow toward the main radiator 16 or the first bypass. It is controlled whether it flows to the circuit 27 (circulates in the engine 4 again).

The sub control valve 22 is provided in the main circuit 8 between the main control valve 20 and the main radiator 16, and detects the temperature of the coolant near the main circuit 8 to open and close the valve. The sub control valve 22 controls whether the coolant that has passed through the main control valve 20 flows to the main radiator 16 or the second bypass circuit 31 (inflow into the sub circuit 12).

Further, the main circuit 8 is provided with a junction 34 in the vicinity of the inlet (upstream side) of the first pump 18. A circuit for the cooling water flowing out from the first EGR cooler 6 joins the joining portion 34.
Further, the sub circuit 12 is provided with a branch portion 14 in a circuit between the second EGR cooler 10 and the second pump 30, and a sub bypass circuit 36 branched from the branch portion 14 is connected to the junction portion 34. To join. The sub bypass circuit 36 connects the sub circuit 12 and the main circuit 8, and returns the cooling water of the sub circuit 12 to the main circuit 8.

Accordingly, in the merging section 34, the cooling water from the circuit from the main radiator 16, the circuit from the first EGR cooler 6, and the three circuits of the sub-bypass circuit 36 are merged, and the merged cooling water is the first pump. 18 flows.
In addition, a check valve 37 (flowing only in one direction) is provided between the branch portion 14 of the sub circuit 12 and the location where the second bypass circuit 31 joins the sub circuit 12. This is to prevent back flow of the sub-circuit 12 due to competition between the second pump 30 and the first pump 18.

Here, the distribution form of the cooling water flowing through the main circuit 8 and the sub circuit 12 will be described according to the temperature of the cooling water flowing through the main circuit 8 based on the operating state of the engine 4.
The temperature of the cooling water in the main circuit (near the main control valve 20 and the sub control valve 22) during normal operation (normal operation) is 85 ° C. (lower limit value) to 95 ° C. (upper limit value) here. It is said.

In addition, as a temperature of the cooling water at the steady state of the engine, a lower limit value may be set to 80 ° C. and an upper limit value may be set to 100 ° C. Further, the lower limit value of the temperature of the cooling water at the steady state of the engine may be any value in the range of 70 ° C. to 90 ° C., and the upper limit value may be any value in the range of 90 ° C. to 120 ° C.
The lower limit value of the temperature of the cooling water in the steady state of the engine varies depending on engine friction and the engine friction based on the temperature. If the engine oil is not warmed, it will be highly viscous and will cause loss due to friction, resulting in poor fuel consumption. The upper limit varies depending on the boiling of water and the durability of engine parts. For example, in high altitudes, it boils even below 90 ° C. Although the boiling point of cooling water increases when pressurized, the upper limit is limited by the heat resistance and durability against heat load of the components used for engine components. In view of these circumstances, the lower limit value and the upper limit value have different ranges or value ranges.

First, the case where the engine 4 is warming up will be described.
In this case, the coolant temperature of the main circuit 8 is in a range that is less than the lower limit (85 ° C.) of the steady state temperature.
At this time, the main control valve 20 is in a closed state by detecting the temperature of the cooling water, and all the cooling water is divided by the main control valve 20 and flows to the first bypass circuit 27, and passes through the first pump 18. The cooling water circulates in the engine 4 again.
That is, the cooling water of the main circuit 8 is driven by the first pump 18 to flow through the first bypass circuit 27 from the inside of the engine 4, is returned to the first pump 18 again, and is sent to the engine 4. A warm-up state is circulated through the engine 4.

A part of the cooling water flowing through the main circuit 8 is used for cooling the first EGR cooler 6, and the cooling water that has passed through the first EGR cooler 6 is returned to the main circuit 8. Here, the cooling water for the first EGR cooler 6 is led out from the engine 4 and circulates through the first EGR cooler 6, and then sent to the merging portion 34 to send the cooling water from the main radiator 16 or the like. And then returned to the engine 4 again.
In addition, the flow form of the cooling water related to the first EGR cooler 6 is constant and does not change depending on the operating state of the engine 4.

On the other hand, the sub circuit 12 forms an independent cooling water circuit different from the main circuit 8 for cooling the engine 4. The cooling water in the sub-circuit 12 is driven by the second pump 30 to flow through the sub-radiator 28, passes through the second EGR cooler 10, and returns to the second pump 30 again.
In this case, when the second pump 30 is an electric pump and cooling by the second EGR cooler 10 is not necessary, the second pump 30 may not be driven.

Next, a case where the engine is stationary will be described.
In this case, the temperature of the cooling water in the main circuit 8 is in the range from the lower limit value to the upper limit value (85 ° C. to 95 ° C.) of the steady state temperature.
First, the main circuit 8 will be described. The main control valve 20 of the main circuit 8 detects the coolant temperature and opens the valve, and the coolant flows toward the main radiator 16 through the main circuit 8.
On the other hand, the sub-control valve 22 is also in an open state, the cooling water passes through the sub-control valve 22, flows through the main circuit 8 toward the main radiator 16, and the sub-circuit 12 is in a closed state. There is no flow to the second bypass circuit 31.

In the normal temperature range of the cooling water, the main control valve 20 repeatedly opens and closes due to a change in the water temperature (intermediate open state), whereby the cooling water flows toward the main radiator 16 or the first bypass circuit 27. The temperature of the cooling water is kept constant while flowing toward

As a normal cooling water circulation mode when the engine 4 is in a steady state, the cooling water driven by the first pump 18 circulates inside the engine 4, and from the main control valve 20 (open to the main circuit) to the main circuit. 8 to the sub-control valve 22, and is sent from the sub-control valve 22 (open to the main circuit, fully closed to the sub circuit) to the main radiator 16 and returned to the first pump 18 again. The main circuit 8 is circulated.

Next, the sub circuit 12 will be described. The second pump 30 forms a circulation circuit related to the cooling water sub-circuit 12 independent of the main circuit 8 for cooling the engine 4.
This sub-circuit 12 is maintained as an independent circuit so long as there is no inflow and outflow of the cooling water. Even if a negative pressure is generated in the branching section 14 from the sub circuit 12 to the main circuit 8 and the circuit is depressurized, the cooling water does not flow out from the sub circuit 12 to the main circuit 8.

When the engine 4 is in a steady state, the cooling water flow in the sub-circuit 12 is driven by the second pump 30 to flow through the sub-radiator 28, passes through the second EGR cooler 10, and again passes through the second pump 30. Is returned to circulates through the sub-circuit 12. This sub-circuit 12 is a circuit whose cooling water has a lower water temperature than the main circuit 8. The amount of cooling water in the sub circuit 12 is, for example, 30 L / min.

Next, the case where the engine is operating at a high load will be described.
In this case, the coolant temperature of the main circuit 8 exceeds the upper limit (95 ° C.) of the steady state temperature. At this temperature, the engine is in a state just before overheating.
When the coolant temperature exceeds the upper limit, the main control valve 20 of the main circuit 8 detects the coolant temperature and opens the valve, while the sub control valve 22 of the main circuit 8 The temperature of the water is detected and narrowed from an open state to a slightly closed state. Then, the cooling water of the main circuit 8 is diverted to the second bypass circuit 31 by the sub control valve 22 and flows to the sub circuit 12.
However, the sub control valve 22 is such that the flow path to the main circuit 8 is slightly closed (not fully closed), a part of the cooling water is diverted to the sub circuit 12, and the rest is circulated through the main circuit 8. . In this case, the flow rate to the sub circuit 12 can be increased by increasing the resistance on the main circuit 8 side.

At this time, although depending on the degree of opening of the sub control valve 22, a part of the cooling water of the main circuit 8 is diverted (for example, 50 L / min) and flows (joins) through the second pump 30 through the sub circuit 12. . At this time, the amount of cooling water in the sub circuit 12 is added to the original amount (30 L / min) by the amount (50 L / min) flowing from the main circuit.
Then, the cooling water (30 + 50 L / min) of the sub circuit 12 is cooled by the sub radiator 28, flows through the second EGR cooler 10, and reaches the second pump 30. Of the cooling water flowing through the sub-circuit 12, the amount of water (50 L / min) divided from the main circuit 8 is returned to the main circuit 8 from the branching section 14 again.

The circulation form of the cooling water in the main circuit 8 is the same as that in the steady state except for the diversion by the sub-control valve 22, and the cooling water driven by the first pump 18 circulates inside the engine 4 to The flow from the control valve 20 (open) toward the sub-control valve 22 is sent from the sub-control valve 22 (open) to the main radiator 16 and returned to the first pump 18 again.

FIG. 2 shows the flow form of the cooling water in the sub circuit 12 (and a part of the main circuit 8).
A part of the cooling water of the main circuit 8 is diverted (5 OL / min) from the sub control valve 22 and flows into the inlet of the second pump 30 via the second bypass circuit 31. In addition, there is a circuit that flows into the sub-circuit 12 downstream of the second pump via a third bypass circuit 32 described later.
Furthermore, cooling water (30 L / min) that has passed through the branch portion 14 and passed through the sub-circuit 12 flows into the inlet of the second pump 30.

Then, cooling water joins the inlet of the second pump 30 (30 + 50 L / min), and further flows through the sub-radiator 28 via the sub-circuit 12 via the outlet of the second pump 30.
Of the cooling water that has passed through the second EGR cooler 10 via the sub-radiator 28, the cooling water (50 L / min) that has been diverted at the branching portion 14 of the sub-circuit 12 passes through the sub-bypass circuit 36 and the junction 34. Further, it is driven by the first pump 18 to flow through the engine 4, passes through the main circuit 8, reaches the sub control valve 22 through the main control valve 20.
Further, the cooling water (30 L / min) that has not been diverted from the branch portion 14 of the sub-circuit 12 flows through the sub-circuit 12 and flows into the second pump 30 as it is.

Thus, the sub circuit 12 is subordinate to the main circuit 8, and the cooling water cooled by the sub radiator 28 of the sub circuit 12 contributes to cooling of the engine 4 of the main circuit 8. As described above, during the high load operation of the engine 4, the switching control of the flow of the cooling water is performed, and the sub-radiator 28 that cools the cooling water to a low water temperature is used to compensate for the decrease in the heat radiation amount of the main radiator 16.

FIG. 3 is a block diagram showing a configuration of an engine cooling device 40 according to another embodiment.
Here, with regard to the configuration of the engine cooling device 40, the same components as those of the engine cooling device 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

The cooling device 40 is provided with a third bypass circuit 32 in place of the second bypass circuit 31 according to the engine cooling device 2, and the cooling water of the main circuit 8 diverted by the sub control valve 22 is supplied to the sub circuit. 12 is merged.
The third bypass circuit 32 communicates the sub control valve 22 with the sub circuit 12 downstream of the second pump 30 (between the second pump 30 and the sub radiator 28). The third bypass circuit 32 bypasses the second pump 30. By bypassing the second pump 30, it is possible to avoid the influence on the second pump 30 due to the hydraulic pressure of the first pump 18 (the output is larger than that of the second pump 30).

Further, when a part of the cooling water flows from the main circuit 8 to the sub circuit 12 via the third bypass circuit 32 by the sub control valve 22, the second pump 30 may not be driven. .
In a state where the second pump 30 is not driven, the cooling water can flow through the pump. In this case, the cooling water flowing into the sub circuit 12 from the sub control valve 22 via the third bypass circuit 32 flows back through the sub circuit 12, passes through the second pump 30, and has a low pressure. Distribution to the pump 18 is expected.
For this reason, a check valve 37 is provided between the branch portion 14 of the sub circuit 12 and the second pump 30 to prevent back flow of the sub circuit 12.

According to the third bypass circuit 32, the sub circuit 12 is subordinate to the main circuit 8, and the first pump 18 of the main circuit 8 has a higher output than the second pump 30. The cooling water of both the main circuit 8 and the sub circuit 12 can be circulated by the pump 18. According to the first pump 18, in addition to driving the main circuit 8, a circuit that reaches the sub circuit 12 from the main circuit 8 via the third bypass circuit 32 and returns from the sub circuit to the main circuit 8 again. The cooling water is driven to flow. For this reason, the drive by the 2nd pump 30 becomes unnecessary.

The cooling device 40 is the same as the configuration and circuit of the cooling device 2 of the engine, except for the third bypass circuit 32 and the circuit related thereto.
In the cooling device 40, when the coolant temperature of the main circuit 8 exceeds the upper limit value (95 ° C.) of the steady state temperature, the sub control valve 22 of the main circuit 8 detects the coolant temperature. It is narrowed from an open state to a slightly closed state. Then, the cooling water is diverted to the third bypass circuit 32 by the sub control valve 22 and flows to the sub circuit 12 via the third bypass circuit 32.
Thereby, the sub circuit 12 is subordinate to the main circuit 8, and the cooling water cooled by the sub radiator 28 of the sub circuit 12 contributes to cooling of the engine 4 of the main circuit 8 as described above.

Therefore, according to the above-described embodiment, the cooling capacity of the sub-radiator for low water temperature provided for improving fuel efficiency is used as a radiator to assist the main radiator temporarily (during high load operation), thereby The size of the radiator can be set to match the low / medium load operation. Therefore, it is possible to configure a main radiator that is smaller than the conventional one, avoiding an increase in the size of the main radiator, and contributing to cost reduction and effective use of the radiator mounting space.

Next, the engine cooling device 42 according to the second embodiment will be described.
FIG. 4 is a block diagram showing the configuration of the engine cooling device 42.
Here, regarding the configuration of the engine cooling device 42, the same components as those of the engine cooling device 2 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
The cooling device 42 includes a main circuit 8 in which cooling water circulates between the main radiator 16 and the engine 4, and a sub circuit in which low-temperature cooling water circulates between the sub radiator 28, the second EGR cooler 10, and the intercooler 38. 12.
As described above, the sub-circuit 12 is provided with the intercooler 38.

The main circuit 8 includes an engine 4, a main radiator 16, a first pump 18, a main control valve 20, a sub control valve 22, and a first EGR cooler 6. The main circuit 8 is provided with a first bypass circuit 27 and a second bypass circuit 31.
The sub-circuit 12 includes a sub-radiator 28, a second EGR cooler 10, a second pump 30, and an intercooler 38.

The intercooler 38 is branched from the sub-circuit 12 extending from the second pump 30 to the sub-radiator 28, and is provided in a state where the diverted cooling water flows in. The cooling water flowing out from the intercooler 38 is The EGR cooler 10 joins the downstream sub-circuit 12.

The cooling device 42 is the same as the configuration and circuit of the engine cooling device 2 according to the first embodiment except for the intercooler 38 and the circuit related thereto.
The intercooler 38 shows an example in which the sub-circuit 12 that circulates between the sub-cooler 28 is configured. Therefore, the cooling device 42 has a configuration in which the intercooler 38 and the second EGR cooler 10 are provided as cooler devices that constitute the circulation circuit with the sub radiator 28.

Also for this cooling device 42, the circulation form of the cooling water that circulates through the main circuit 8 and the sub circuit 12 according to the operating state of the engine 4 (except for the circulation related to the intercooler 38), It is the same.
Further, the sub-circuit 12 is provided with a branch portion 14, and cooling water flowing through the sub-circuit 12 under a predetermined condition flows into the main circuit 8 from the branch portion 14, flows through the engine 4, and again flows into the main circuit. 8 is returned to the sub-circuit 12. Thereby, the sub circuit 12 is subordinate to the main circuit 8, and the cooling water cooled by the sub radiator 28 of the sub circuit 12 contributes to cooling of the engine 4 of the main circuit 8.

Therefore, according to the second embodiment, as in the first embodiment, the main radiator can be set to a size adjusted during low / medium load operation, and the main radiator can be increased in size. It is avoided and contributes to cost reduction and effective use of the radiator mounting space.

Next, an engine cooling device 44 according to a third embodiment will be described.
FIG. 5 is a block diagram showing the configuration of the engine cooling device 44.
Here, regarding the configuration of the engine cooling device 44, the same components as those of the engine cooling device 2 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

The engine cooling device 44 includes a main circuit 8 for cooling water that cools the engine 4 and a sub-circuit 12 that cools the second EGR cooler 10 and the first EGR cooler 6 with cooling water having a low water temperature. It has two circuits.

The main circuit 8 is provided with an engine 4, a main radiator 16, a first pump 18, a main control valve 20, and a sub control valve 22. The main circuit 8 is provided with a first bypass circuit 27 and a second bypass circuit 31.
The sub circuit 12 is provided with a sub radiator 28, a second EGR cooler 10, a first EGR cooler 6, and a second pump 30.
The sub-circuit 12 forms a circulation circuit in which the cooling water from the sub-radiator 28 is circulated through the second EGR cooler 10, the first EGR cooler 6 is further circulated, and returned to the sub-radiator 28 again.

The cooling device 44 is the same as the configuration and circuit of the engine cooling device 2 of the first embodiment except for the circuit related to the second EGR cooler 10.
Also for this cooling device 44, the cooling water flowing through the main circuit 8 and the sub circuit 12 in accordance with the operating state of the engine 4 (except for the flow related to the second EGR cooler 10) is the cooling of the engine. This is the same as the device 2.
Further, the sub-circuit 12 is provided with a branch portion 14, and cooling water flowing through the sub-circuit 12 under a predetermined condition flows into the main circuit 8 from the branch portion 14, flows through the engine 4, and again flows into the main circuit. 8 is returned to the sub-circuit 12. Thereby, the sub circuit 12 is subordinate to the main circuit 8, and the cooling water cooled by the sub radiator 28 of the sub circuit 12 contributes to cooling of the engine 4 of the main circuit 8.

Therefore, according to the third embodiment, as in the first embodiment, the main radiator can be set to a size that is adjusted during low / medium load operation, and the main radiator can be increased in size. It is avoided and contributes to cost reduction and effective use of the radiator mounting space.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2011-258712 filed on Nov. 28, 2011, the contents of which are incorporated herein by reference.

4: engine, 6: EGR cooler / (first EGR cooler), 8: main circuit, 9: derivation circulation circuit, 10: cooler device (second EGR cooler), 12: sub circuit, 14: branching section, 16: main radiator, 18: first pump, 20: main control valve, 22: sub-control valve, 28: sub-radiator, 30: second pump, 31: bypass circuit (second bypass circuit), 32: Bypass circuit (third bypass circuit), 38: cooler equipment (intercooler)

Claims

A main radiator for cooling the cooling water flowing through the engine;
A main circuit of cooling water circulating through the engine and the main radiator;
A first pump provided on the upstream side of the engine of the main circuit and driving the coolant to flow;
A sub-radiator that cools cooling water used in a cooler device that cools an in-vehicle heating element independently of the main circuit;
A sub-circuit of cooling water circulating through the cooler device and the sub-radiator;
A second pump that is provided in the middle of the sub-circuit and drives the cooling water of the sub-circuit to flow through;
The temperature of the cooling water in the main circuit is detected, and when this temperature exceeds the upper limit value of the cooling water temperature in the steady state of the engine, a part of the cooling water to be sent to the main radiator is diverted to the sub circuit. A sub-control valve to send to
The cooling water sent to the sub circuit by the sub control valve is cooled by the sub radiator and flows into the cooler device, and the cooling water of the sub circuit is diverted and the first pump of the main circuit The engine cooling apparatus is characterized by being returned to the upstream side of the engine.
If the temperature of the cooling water in the main circuit is detected and this temperature is less than the lower limit value of the cooling water temperature during steady operation of the engine, the cooling water that has passed through the engine is returned to the engine to warm the engine. A main control valve is provided that sends a part or all of the cooling water that has passed through the engine to the main radiator of the main circuit when the temperature is equal to or higher than the lower limit. Item 4. The engine cooling device according to Item 1.
The engine cooling device according to claim 1 or 2, wherein the lower limit value of the temperature of the cooling water during steady operation of the engine is 80 ° C and the upper limit value is 100 ° C.
The lower limit value of the temperature of the cooling water in a steady state of the engine is any value in the range of 70 ° C to 90 ° C, and the upper limit value is any value in the range of 90 ° C to 120 ° C. Item 3. The engine cooling device according to Item 1 or 2.
The bypass circuit which sends the cooling water branched by the sub control valve to the sub circuit on the upstream side or the downstream side of the second pump is provided. Engine cooling system.
The engine cooling device according to any one of claims 1 to 5, wherein an EGR cooler is provided in a lead-out circulation circuit that divides cooling water from the main circuit.
The engine cooling device according to any one of claims 1 to 5, wherein an EGR cooler is provided in the middle of the sub-circuit.
Using the engine cooling device according to any one of claims 1 to 7, a part of the cooling water of the main circuit is sent to the sub circuit, the cooling water is cooled by the sub radiator, and again A method for cooling an engine, comprising returning the main circuit to the upstream side of the engine.