WO2010106615A1

WO2010106615A1 - Engine cooling device

Info

Publication number: WO2010106615A1
Application number: PCT/JP2009/055018
Authority: WO
Inventors: 星幸一; 篠田祥尚; 池田晃浩; 新谷治
Original assignee: トヨタ自動車株式会社
Priority date: 2009-03-16
Filing date: 2009-03-16
Publication date: 2010-09-23
Also published as: CN102356220A; US20110265740A1; JP5267654B2; JPWO2010106615A1

Abstract

An engine cooling device (100) is provided with a water pump (10) for pumping cooling water (W) used in common in cooling water circulation passages (81-86), an engine (20) equipped with an engine body (21), a water-cooled exhaust manifold (30) having a smaller heat capacity than the engine body (21) and cooling an exhaust system of the engine (20) by the flowing cooling water (W), a radiator (50) for cooling the flowing cooling water (W), and an ECU (1) and a thermostat (60) which control flow of the cooling water (W) by determining, based on a predetermined judgment value, whether or not the cooling water (W) is to be caused to flow to the fifth and sixth cooling water circulation passages (85, 86), in which a radiator (50) is mounted, among the cooling water circulation passages (81-86). The predetermined judgment value is a value relating to the amount of heat which the cooling water (W) receives in the water-cooled exhaust manifold (30) from exhaust gas.

Description

Engine cooling system

The present invention relates to an engine cooling device, and more particularly to an engine cooling device provided with an exhaust system cooling means for cooling an engine exhaust system with a refrigerant common to the refrigerant circulating in the engine body.

Conventionally, a technique for cooling an engine exhaust system (specifically, for example, an exhaust manifold) with a coolant such as water is known. With regard to such technology, for example, Patent Literature 1 discloses a technology considered to be related to the present invention. Patent Document 1 discloses an exhaust manifold device including a water jacket formed around an exhaust manifold and water injection means for injecting water into the water jacket in a spray form. In addition, as a technique considered to be related to the present invention, for example, Patent Document 2 discloses a cooling control device for an internal combustion engine provided with a flow rate control valve that can change the supply ratio of the cooling medium to a plurality of cooling units. ing. Specifically, Patent Document 2 discloses a cooling control device for an internal combustion engine in which a flow rate control valve is provided in each cooling water passage that guides cooling water to a plurality of cooling units such as exhaust ports.

JP-A-63-208607 JP 2007-132313 A

By the way, in an engine, it is required to reduce exhaust emission as an approach to environmental problems. In this regard, in order to reduce exhaust emissions mainly during light and medium load operation, there is a method in which the three-way catalyst is arranged close to the engine and the three-way catalyst is warmed up early.

On the other hand, in order to reduce exhaust emissions during high load operation using the above method, it is desirable to operate the engine at or near the stoichiometric air / fuel ratio. However, in this case, the catalyst is overheated due to the arrangement of the catalyst in the vicinity of the engine, and as a result, there is a concern about excessive progress of deterioration and deterioration of exhaust emission due to excessive progress of deterioration. Therefore, considering the reduction of exhaust emission in the high load operation region, it is necessary to dispose the three-way catalyst away from the engine. However, this may result in insufficient exhaust emission reduction in a light and medium load operation region where the catalyst is warmed up early, and thus it is necessary to increase the amount of noble metal that promotes purification of the catalyst. However, since these noble metals are rare, in this case, there is a concern about an increase in cost.

Under these circumstances, the exhaust system is used for the purpose of suitably balancing exhaust emissions in the light and medium load operating range where the catalyst is warmed up early and further reducing exhaust emissions during high load operation. It is considered that the exhaust gas is cooled with a refrigerant to lower the exhaust temperature. In this way, it is possible to suppress overheating of the catalyst. Therefore, in this way, the catalyst can be arranged close to the engine, so that the exhaust emission in the light and medium load operation region where the catalyst is warmed up early and the exhaust emission during the high load operation are updated. It is also possible to achieve both reductions that are suitable.

On the other hand, when cooling the exhaust system with a refrigerant, it is reasonable to use a common refrigerant with the refrigerant circulating in the engine body (for example, long-life coolant that is engine cooling water) from the viewpoint of cost. It is done. In this regard, the refrigerant flowing through the engine body is generally cooled by a cooler (for example, a radiator). Whether or not the refrigerant flows through the cooler is generally determined based on the temperature of the refrigerant flowing through the refrigerant circulation path including the engine body.

However, there is a partial variation in the temperature of the refrigerant flowing through the refrigerant circulation path. Therefore, more specifically, whether or not the refrigerant is circulated through the cooler is more generally determined by the temperature of the refrigerant in the part on the outlet side of the engine body or in the distribution path immediately after flowing through the engine body. It has been decided. And if it determines in this way, it can prevent or suppress that an engine is damaged by the overheating of a refrigerant | coolant.

However, when an exhaust system cooling means for cooling the exhaust system with a refrigerant common to the refrigerant flowing through the engine body is provided, the exhaust system cooling means is usually smaller in size than the engine body, so the exhaust system cooling means is more suitable. The heat capacity is smaller than the engine body. For this reason, when such an exhaust system cooling means is provided, the degree of the influence received by the transfer of heat is larger in the exhaust system cooling means than in the engine body, including the circulating refrigerant. Therefore, in this case, when it is determined whether or not to circulate the refrigerant through the cooler as described above, the refrigerant exceeds the appropriate temperature in the exhaust system cooling means having a small heat capacity before the refrigerant is actually circulated through the cooler. Alternatively, there is a possibility that a boiling situation may occur, and as a result, there is a problem in that the engine may be damaged.

Therefore, the present invention has been made in view of the above problems, and when the exhaust system cooling means for cooling the exhaust system of the engine with the refrigerant common to the refrigerant circulating in the engine body is provided, the refrigerant is overheated by the exhaust system cooling means. Alternatively, an object of the present invention is to provide an engine cooling device that can prevent or suppress boiling and damage to the engine.

In order to solve the above problems, an engine cooling device according to the present invention includes a refrigerant pressure feeding device that pumps a common refrigerant to a plurality of refrigerant circulation paths, and an engine in at least one refrigerant circulation path among the plurality of refrigerant circulation paths. An engine incorporating a main body, and an exhaust gas that is incorporated in at least one refrigerant circulation path among the plurality of refrigerant circulation paths, has a smaller heat capacity than the engine main body, and cools the engine exhaust system with a circulating refrigerant. A system cooling means, a cooler that is incorporated in at least one refrigerant circulation path among the plurality of refrigerant circulation paths and cools the circulating refrigerant, and the cooler is incorporated among the plurality of refrigerant circulation paths. A flow control device that determines whether or not to circulate the refrigerant through at least one refrigerant circulation path based on a predetermined determination value and controls the flow of the refrigerant; For example, the predetermined determination value, the refrigerant in the exhaust system cooling means is a cooling device for an engine was determined value according to the heat amount received from the exhaust.

Further, the present invention is incorporated in at least one refrigerant circulation path in which the exhaust system cooling means is incorporated among the plurality of refrigerant circulation paths, and the pressure of the refrigerant flowing through the exhaust system cooling means is the plurality of refrigerants. It is preferable to further include a flow rate adjusting means for adjusting the flow rate of the refrigerant discharged from the exhaust system cooling means so as to be higher than the system pressure of the circulation path.

According to the present invention, when the exhaust system cooling means for cooling the exhaust system of the engine with the refrigerant common to the refrigerant flowing through the engine body is provided, the refrigerant is overheated or boiled by the exhaust system cooling means, and the engine is damaged. Can be prevented or suppressed.

1 is a diagram schematically illustrating an engine cooling device (hereinafter simply referred to as a cooling device) 100 according to an embodiment. In FIG. 1, piping and the like constituting the cooling water circulation path during cold when the thermostat 60 is closed are indicated by broken lines, and piping and the like constituting the cooling water circulation path during warming when the thermostat 60 is opened are indicated by solid lines. While showing each, the flow direction of the cooling water W is shown with the arrow with respect to these. This also applies to FIGS. 3 to 8. 1 is a diagram schematically showing a water-cooled exhaust manifold (hereinafter simply referred to as a water-cooled exhaust manifold) 30. FIG. It is a figure which shows the 1st cooling water circulation path | route 81. FIG. It is a figure which shows the 2nd cooling water circulation path. It is a figure which shows the 3rd cooling water circulation path | route 83. FIG. It is a figure which shows the 4th cooling water circulation path. It is a figure which shows the 5th cooling water circulation path. It is a figure which shows the 6th cooling water circulation path 86. FIG. It is a figure which shows typically the specific structure of ECU1. It is a figure which shows a mode that the cooling water temperature THW rises with the rotation speed NE and the change of the vehicle speed SPD. In addition, in FIG. 10, the case of the cooling device 100 is indicated by a solid line with respect to the cooling water temperature THW, and the case of the cooling device 100X that is substantially the same as the cooling device 100 is indicated by a broken line except that the water cooling exhaust manifold 30 is not provided. Yes. FIG. 4 is a diagram showing the flow rate of cooling water W flowing through the water-cooled exhaust manifold 30 according to the open / close state of the thermostat 60. It is a figure which shows operation | movement of ECU1 with a flowchart. It is a figure which illustrates typically the control which forcibly opens the thermostat. The flow rate of the cooling water W flowing through the water-cooled exhaust manifold 30 during warming is indicated by a solid line for the cooling device 100, and a broken line for the cooling device 100Y that is substantially the same as the cooling device 100Y except that the orifice 70 is not provided. It is a figure shown by. It is a figure which shows the mode of the change of the inlet pressure P1 and the outlet pressure P2 of the water-cooled exhaust manifold 30 at the time of a high temperature test with the change of vehicle speed SPD, water temperature THW, and rotation speed NE.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

The cooling device 100 will be described with reference to FIGS. The cooling device 100 includes an ECU (Electronic Control Unit) 1, a water pump 10, an engine 20, a water-cooled exhaust manifold 30, a heater core 40, a radiator 50, a thermostat 60, and an orifice 70. . The water pump 10 is assembled to the engine 20. The water pump 10 is a mechanical pump that is driven by the output of the engine 20 and pumps the cooling water W that is a refrigerant.

The engine 20 has an engine body 21. The engine main body 21 includes a cylinder head and a cylinder block (not shown). In the engine body 21, a water jacket 22, a bypass passage 23, and a communication passage 24 are formed. The cooling water W flows through the water jacket 22, and the cooling water W flowing through the water pump 22 cools the engine body 21. The bypass passage 23 circulates the cooling water W from the water jacket 22 to the thermostat 60. In this regard, the bypass passage 23 specifically communicates the outlet side portion of the water jacket 22 with the outside. The communication passage 24 communicates the inlet side portion of the bypass passage 23 and the outside. The engine main body 21 is provided with a water temperature sensor 91 that detects a cooling water temperature THW that is the temperature of the cooling water W, and an engine speed sensor 92 that is used to detect the speed NE of the engine 20. The water temperature sensor 91 is provided so as to detect the cooling water temperature THW at the outlet side of the water jacket 22.

The water-cooled exhaust manifold 30 is assembled to the engine body 21. The water-cooled exhaust manifold 30 joins the exhaust discharged from each cylinder of the engine 20. As shown in FIG. 2, the water-cooled exhaust manifold 30 includes an outer wall portion 302 that entirely encloses a plurality of exhaust pipes 301. The outer wall portion 302 forms a cooling water flow path between the plurality of exhaust pipes 301. In the water-cooled exhaust manifold 30, the cooling water W is supplied from the cooling water introduction port 303 to the cooling water passage, and the cooling water W is discharged from the cooling water passage through the cooling water discharge port 304. In this embodiment, the water-cooled exhaust manifold 30 is an exhaust system cooling means.

Referring back to FIG. 1, the heater core 40 exchanges heat between the cooling water W and air. The heater core 40 is used in an air conditioner (not shown). The air conditioner functions as a heating device by blowing air heated by the heater core 40 into the vehicle interior of the vehicle. The radiator 50 promotes heat radiation from the cooling water W that is circulated by running wind or air blown by an electric fan (not shown), and cools the cooling water W. In the present embodiment, the radiator 50 is a cooler.

The thermostat 60 is operated to control the flow of the cooling water W by closing when it is cold and opening when it is warm. Further, the thermostat 60 determines whether or not the cooling water W is allowed to flow through the radiator 50 together with the ECU 1 based on a predetermined determination value, and controls the flow of the cooling water W. This predetermined determination value is a determination value related to a cooling loss Qw described later. The thermostat 60 specifically allows the circulation of the cooling water W through the radiator 50 when the cooling loss Qw is equal to or greater than a predetermined determination value under the control of the ECU 1. To control. In this respect, in this embodiment, the thermostat 60 is more specifically controlled under the control of the ECU 1 so that the valve 50 is forcibly opened when the cooling loss Qw is equal to or greater than a predetermined determination value. Authorized distribution.
The orifice 70 adjusts the flow rate of the cooling water W. The orifice 70 is a fixed flow rate type, and reduces the flow rate of the circulating cooling water W by a predetermined amount.

The cooling device 100 has first to sixth cooling water circulation paths 81 to 86 corresponding to a plurality of refrigerant circulation paths. The first, second, and third cooling

water circulation paths

81, 82, and 83 are circulation paths that permit the circulation of the cooling water W when the thermostat 60 is closed. The fourth, fifth, and sixth cooling

water circulation paths

84, 85, 86 are circulation paths that permit the circulation of the cooling water W when the thermostat 60 is opened. Specifically, the water pump 10 pumps the common cooling water W to these cooling water circulation paths 81 to 86. In this embodiment, the water pump 10 is a refrigerant pressure feeding device.

Any of the water pump 10, the engine 20, the water-cooled exhaust manifold 30, the heater core 40, the radiator 50, the thermostat 60, and the orifice 70 is appropriately incorporated in the plurality of cooling water circulation paths 81 to 86. In each of the cooling water circulation paths 81 to 86, these components are connected to each other directly or via piping. Next, the plurality of cooling water circulation paths 81 to 86 will be specifically described with reference to FIGS.

Specifically, the first cooling water circulation path 81 is a circulation path in which the water pump 10, the engine body 21, the heater core 40, and the thermostat 60 are incorporated, and the cooling water W flows in this order. Further, when the engine main body 21 is circulated, the cooling water W specifically circulates through the water jacket 22.
Specifically, the second cooling water circulation path 82 is a circulation path in which the water pump 10, the engine main body 21, and the thermostat 60 are incorporated, and the cooling water W circulates in this order. Further, when the engine body 21 is circulated, the cooling water W specifically circulates through the water jacket 22 and the bypass passage 23 in this order.
Specifically, the third cooling water circulation path 83 is a circulation path in which the water pump 10, the water cooling exhaust manifold 30, the engine main body 21, and the thermostat 60 are incorporated, and the cooling water W circulates in this order. Further, when the engine main body 21 is circulated, the cooling water W specifically circulates through the communication path 24 and the bypass path 23 in this order.
The first to third cooling water flow paths 81 to 83 are circulation paths that do not include the radiator 50.

Specifically, the fourth cooling water circulation path 84 is a circulation path in which the water pump 10, the engine body 21, the heater core 40, and the thermostat 60 are incorporated, and the cooling water W flows in this order. Further, when the engine main body 21 is circulated, the cooling water W specifically circulates through the water jacket 22.
Specifically, the fifth cooling water circulation path 85 is a circulation path in which the water pump 10, the engine body 21, the radiator 50, and the thermostat 60 are incorporated, and the cooling water W flows in this order. Further, when the engine main body 21 is circulated, the cooling water W specifically circulates through the water jacket 22.
Specifically, the sixth cooling water circulation path 86 includes a water pump 10, a water cooling exhaust manifold 30, an orifice 70, a radiator 50, and a thermostat 60, and a circulation path through which the cooling water W flows in this order. It has become.
In the plurality of cooling water circulation paths 81 to 86 configured as described above, the cooling water W does not circulate in the water cooling exhaust manifold 30 when the thermostat 60 is opened and closed (in other words, the radiator 50 is not circulated). The cooling water W is circulated in both cases.

As shown in FIG. 8, specifically, the orifice 70 is a portion downstream of the water-cooled exhaust manifold 30 and a portion before the radiator 50 in the sixth coolant circulation path 86 in which the water-cooled exhaust manifold 30 is incorporated. Is provided. More specifically, the orifice 70 is provided at a portion downstream of the water-cooled exhaust manifold 30 and at a portion before the junction with the fifth cooling water circulation path 85 which is another cooling water circulation path. The orifice 70 specifically reduces the flow rate of the circulating cooling water W by a predetermined amount, whereby the pressure of the cooling water W flowing through the water-cooled exhaust manifold 30 is changed to the system pressure from the plurality of cooling water circulation paths 81 to 86. The flow rate of the cooling water W discharged from the water-cooled exhaust manifold 30 is adjusted so as to be higher. This system pressure is specifically the radiator cap pressure of the radiator 50. In this embodiment, the orifice 70 is a flow rate adjusting means.

As shown in FIG. 9, the ECU 1 includes a microcomputer composed of a CPU 2, a ROM 3, a RAM 4, and the like, and input / output circuits 5 and 6. The CPU 2, ROM 3, RAM 4, and input / output circuits 5 and 6 are connected to each other via a bus 7. The ECU 1 is mainly configured to control the engine 20. Specifically, the ECU 1 is configured to control, for example, a fuel injection valve (not shown). In addition, the ECU 1 is configured to control the thermostat 60. These objects to be controlled are electrically connected to the ECU 1.

The ECU 1 is electrically connected to various sensors such as a water temperature sensor 91, an engine speed sensor 92, and an air flow meter 93 (more specifically, an intake air amount sensor 93a and an intake air temperature sensor 93b). The cooling water temperature THW is based on the output of the water temperature sensor 91, the rotational speed NE is based on the output of the engine rotational speed sensor 92, and the intake air amount GA and the intake air temperature THA of the engine 20 are based on the output of the air flow meter 93. Each is detected.
The ROM 3 is configured to store programs, map data, and the like in which various processes executed by the CPU 2 are described. When the CPU 2 executes processing while using the temporary storage area of the RAM 4 as necessary based on the program stored in the ROM 3, the ECU 1 has various control means, determination means, detection means, calculation means, and the like. To be realized.

In this regard, the ECU 1 is based on detection means for detecting a plurality of estimation factors including the intake air amount GA of the engine 20 and the amount of heat received by the refrigerant from the exhaust gas in the water-cooled exhaust manifold 30 based on the plurality of estimation factors detected by the detection means. An estimation means for estimating a certain cooling loss Qw is functionally realized. The cooling loss Qw can be used to detect whether or not the operating state of the engine 20 is in a high load operating state.
The plurality of estimation factors described above include the intake air amount GA because the intake air amount GA has a high linear correlation with the cooling loss Qw.
The plurality of estimation factors described above preferably further include at least one of the coolant temperature THW, the intake air temperature THA, or the rotational speed NE, which is the refrigerant temperature. This is because these four factors have a great influence on the cooling loss Qw.

Specifically, for example, if the operating environment conditions of the engine 20 such as the initial state are different, the cooling loss Qw is also different. On the other hand, the coolant temperature THW and the intake air temperature THA can represent the operating environment conditions of the engine 20. Further, if the friction of the engine 20 increases, the amount of heat generated from the engine 20 increases, so that the cooling loss Qw also tends to increase. On the other hand, the rotational speed NE can represent the magnitude of the friction of the engine 20. For this reason, in estimating the cooling loss Qw with higher accuracy, it is preferable to further include at least one of the cooling water temperature THW, the intake air temperature THA, and the rotational speed NE.

Further, the plurality of estimation factors described above are most preferably estimated based on the following formula (1) in which the cooling loss Qw includes all these four factors.
Qw = (THW + THA) × NE × GA (1)
That is, the cooling loss Qw is most preferably estimated based on a value calculated by the product of the sum of the coolant temperature THW and the intake air temperature THA, the rotational speed NE, and the intake air amount GA. This is because, when the cooling loss Qw is estimated based on the equation (1) by experiment, the highest linear correlation is recognized with the actual cooling loss Qw. Therefore, the ECU 1 specifically estimates the cooling loss Qw based on the equation (1).

Further, the ECU 1 functionally realizes a control means for determining whether or not the cooling water W is allowed to flow through the radiator 50 based on a predetermined determination value related to the cooling loss Qw. Specifically, the control means functions to control the thermostat 60 so as to permit the flow of the cooling water W through the radiator 50 when the estimated cooling loss Qw, which is the received heat amount, is equal to or greater than a predetermined determination value. Is realized. In this respect, in this embodiment, more specifically, the control means is functionally realized so as to perform control to forcibly open the thermostat 60 when the cooling loss Qw is equal to or greater than a predetermined determination value. Thereby, the control means is functionally realized so as to determine whether or not the cooling water W is circulated through the fifth and sixth cooling

water circulation paths

85 and 86 in which the radiator 50 is incorporated. In this embodiment, the thermostat 60 and the ECU 1 are the flow control device.

Next, the function and effect of the cooling device 100 will be described. In the cooling device 100, the thermostat 60 is closed when it is cold (for example, when the coolant temperature THW is 75 ° C. or lower). For this reason, in the cooling device 100, the cooling water W flows through the first to third cooling

water circulation paths

81, 82, and 83 when cold. Each of the first to third cooling

water circulation paths

81, 82, and 83 is a circulation path that does not include the radiator 50. Therefore, in the cooling device 100, the cooling water W flowing through the engine main body 21 during the cold state is basically not cooled by the radiator 50. For this reason, in the cooling device 100, the warm-up property of the engine 20 is thereby improved.

In the cooling device 100, the cooling water W flowing through the third cooling water circulation path 83 flows through the communication passage 24 and the bypass passage 23 formed in the engine body 21 after flowing through the water-cooled exhaust manifold 30. . Therefore, in the cooling device 100, the heat received by the cooling water W from the exhaust gas by the water-cooled exhaust manifold 30 at the time of cold can be used for warming up the engine 20, thereby further improving the warm-up performance of the engine 20. . As a result, the cooling device 100 can improve the warm-up performance of the engine 20 as compared with the cooling device 100X as shown in FIG.

On the other hand, in the cooling device 100, the thermostat 60 opens when it is warm. For this reason, in the cooling device 100, the cooling water W flows through the fourth to sixth cooling

water circulation paths

84, 85, 86 when it is warm. Each of the fifth and sixth cooling

water circulation paths

85 and 86 is a circulation path including the radiator 50. Therefore, in the cooling device 100, the cooling water W cooled by the radiator 50 during warming is pumped by the water pump 10. For this reason, in the cooling device 100, the water-cooled exhaust manifold 30 included in the sixth cooling water circulation path 86 can thereby be cooled, thereby preventing or suppressing the occurrence of overheating or boiling of the cooling water W in the water-cooled exhaust manifold 30. . That is, according to the cooling device 100, it is possible to improve both the warm-up performance of the engine 20 and to prevent or suppress the occurrence of overheating or boiling of the cooling water W in the water-cooled exhaust manifold 30.

On the other hand, in the cooling device 100, the water-cooled exhaust manifold 30 has a smaller heat capacity than the engine body 21. Therefore, in the cooling device 100, the degree of influence received by the transfer of heat is larger in the water-cooled exhaust manifold 30 than in the engine body 21, including the circulating cooling water W.
In the cooling device 100, the flow rate of the cooling water W flowing through the water-cooled exhaust manifold 30 varies according to the open / close state of the thermostat 60 as shown in FIG. 11. Specifically, the flow rate of the cooling water W flowing through the water-cooled exhaust manifold 30 is smaller in the cold state when the thermostat 60 is closed than in the warm state when the thermostat 60 is opened. This is because the cooling water W flowing through the water-cooled exhaust manifold 30 flows through the third cooling water circulation path 83 when the thermostat 60 is closed, and cooling when flowing through the bypass passage 23 included in the third cooling water circulation path 83. This is because the pressure loss of the water W is large.

Therefore, in the cooling device 100, for example, when a high load operation such as full-open acceleration is performed on the engine 20 immediately after the engine cold start, the heat capacity is small and the flow rate of the circulating cooling water W is small. First, the amount of heat received by the water-cooled exhaust manifold 30 increases rapidly, so that the cooling water W may overheat or boil in the water-cooled exhaust manifold 30 before the engine body 21.

In contrast, in the cooling device 100, the ECU 1 performs an operation based on the flowchart shown in FIG. This flowchart is repeatedly executed at very short time intervals while the engine 20 is operating. The ECU 1 determines whether or not the thermostat 60 is closed (step S1). If the determination is negative, no particular processing is required, and thus this flowchart is temporarily terminated. On the other hand, if an affirmative determination is made in step S1, ECU 1 determines whether or not cooling loss Qw is equal to or greater than a predetermined determination value (step S2).

When the cooling loss Qw is equal to or greater than a predetermined determination value, it is determined that the cooling water W may overheat or boil in the water-cooled exhaust manifold 30. Therefore, if a negative determination is made in step S2, the present flowchart is temporarily terminated, whereas if an affirmative determination is made in step S2, the ECU 1 performs control to forcibly open the thermostat 60 (step S3). Thereby, as shown in FIG. 13, the control which forcibly opens the thermostat 60 is performed. And even if it is a case where the amount of heat receiving in the water-cooled exhaust manifold 30 increases rapidly at the time of cold, the overheating of the cooling water W in the water-cooled exhaust manifold 30 can be prevented or suppressed.

When the ECU 1 estimates the cooling loss Qw, the cooling water temperature THW, the intake air temperature THA, the rotational speed NE, and the intake air amount GA can generally be detected using existing sensors. For this reason, in grasping the use environment state of the water-cooled exhaust manifold 30, for example, the cooling device 100 is compared with a case where a sensor that directly detects the temperature of the cooling water W flowing through the water-cooled exhaust manifold 30 and the temperature of the exhaust is newly provided. This is advantageous in terms of cost.
Further, when the use environment state of the water-cooled exhaust manifold 30 is grasped by using a sensor that directly detects as described above, the thermostat 60 is forced after the fact that the amount of heat received is actually detected. Will be opened. For this reason, in this case, there is a possibility that the responsiveness may be insufficient particularly for a rapid increase in the amount of heat received. On the other hand, the cooling device 100 is superior in terms of responsiveness as compared with such a case.

On the other hand, in contrast to the small heat capacity of the water-cooled exhaust manifold 30, the cooling device 100 further includes the orifice 70 as described above in the portion of the sixth cooling water circulation path 86 downstream of the water-cooled exhaust manifold 30 and the fifth cooling. It is provided in a portion in front of the junction with the water circulation path 85. Therefore, in the cooling device 100, as shown in FIG. 14, the flow rate of the cooling water W decreases in the water-cooled exhaust manifold 30 located on the upstream side of the orifice 70, and the pressure of the cooling water W increases by an amount corresponding to the reduced flow rate. .

Then, the pressure of the cooling water W rises as the cooling water temperature THW rises. In the cooling device 100, as shown in FIG. 15, the outlet pressure P2 of the cooling water W at the cooling water outlet 304 of the water-cooled exhaust manifold 30 is more cooled. It becomes about 50 kPa higher than the inlet pressure P1 of the cooling water W at the water inlet 303. For this reason, in the cooling device 100, the boiling point of the cooling water W in the water-cooled exhaust manifold 30 can be increased, and thus the boiling of the cooling water W in the water-cooled exhaust manifold 30 can be prevented or suppressed when warm. In addition, since only the orifice 70 is provided, for example, an electronic flow control valve is provided for each of the engine main body 21 and the water-cooled exhaust manifold 30 that are to be cooled, and the flow rate of the cooling water W that flows through each cooling target is controlled Compared with, it can also be avoided.
As described above, the cooling device 100 can prevent or suppress the cooling water W from being overheated or boiled by the water-cooled exhaust manifold 30 and resulting in damage to the engine 20.

The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.
For example, in the above-described embodiment, the case where the water-cooled exhaust manifold 30 serving as the exhaust system cooling means has a specific structure as shown in FIG. 2 has been described. However, the present invention is not necessarily limited to this, and the exhaust system cooling means may include other appropriate structures capable of cooling all or part of the exhaust manifold with the refrigerant.

For example, in the above-described embodiment, the case where the cooling exhaust manifold 30 is an exhaust system cooling means has been described. This is because the exhaust gas flowing into the catalyst can be cooled while the catalyst for purifying the exhaust gas is disposed close to the engine 20. However, the present invention is not necessarily limited to this, and the exhaust system cooling means is another appropriate configuration capable of cooling the exhaust that has been discharged from the engine and before flowing into the catalyst with a refrigerant, for example. May be.

Further, for example, in the above-described embodiment, the case where the thermostat 60 and the ECU 1 are distribution control devices has been described. In order to control the circulation of the cooling water W, it is convenient to use a thermostat 60 that can switch whether or not to distribute the cooling water W to the radiator 50 according to the open / close state. This is because it is advantageous from the above.
However, the present invention is not necessarily limited to this. For example, an additional pipe for communicating the radiator 50 and the water pump 10 is provided, and switching means that can permit or block the flow of the cooling water W through the pipe is, for example, electromagnetic. A valve may be further provided. And while making the said electromagnetic valve the control object of ECU1 instead of the thermostat 60, the thermostat 60 is bypassed by opening the said electromagnetic valve in a valve closing state instead of opening the thermostat 60 forcibly. In the form, the cooling water W can be circulated through the radiator 50. In this case, the solenoid valve and the ECU 1 serve as a flow control device.

For example, in the above-described embodiment, the case where the plurality of cooling water circulation paths 81 to 86 are a plurality of refrigerant circulation paths has been described. However, the present invention is not necessarily limited to this, and the plurality of refrigerant circulation paths may be appropriately configured with other appropriate quantities.

Further, for example, in the above-described embodiment, whether or not the cooling water W is circulated through the fifth and sixth cooling

water circulation paths

85 and 86 in which the radiator 50 is incorporated is determined based on a predetermined determination value. The case of controlling distribution has been described. This is because the thermostat 60 and the ECU 1 are used as the flow control device, and in this way, a larger flow rate can be cooled. As a result, the amount of heat received by the water-cooled exhaust manifold 30 increases rapidly. This is because the effect of suppressing overheating or boiling can be enhanced.
However, the present invention is not necessarily limited to this. For example, the cooling water W is circulated only through the sixth cooling water circulation path 86 including the water-cooled exhaust manifold 30 among the fifth and sixth cooling

water circulation pipes

85 and 86. The circulation of the cooling water W may be controlled, and further, for example, the circulation of the cooling water W may be controlled so that the cooling water W is circulated through the fifth cooling water circulation path 85 thereafter.
In this case, it becomes possible to cool the cooling water W step by step according to the degree of necessity, and thus the cooling water W can be cooled while achieving compatibility with the warm-up performance of the engine 20.

Specifically, for example, the fifth cooling water circulation path 85 is further provided with a junction with the sixth cooling water circulation path 86 and a bypass pipe that bypasses the radiator 50, and the distribution destination of the cooling water W is bypassed. For example, an electromagnetic valve can be further provided as switching means capable of switching between the piping or the radiator 50. Then, the solenoid valve is controlled by the ECU 1 together with the thermostat 60, and the solenoid valve is controlled so that the distribution destination when the thermostat 60 is forcibly opened is a bypass pipe. Thereby, circulation of the cooling water W can be controlled so that the cooling water W is circulated only in the sixth cooling water circulation path 86 among the fifth and sixth cooling

water circulation paths

85 and 86.
Further, thereafter, the cooling water W can be circulated through the fifth cooling water circulation path 85 by controlling the electromagnetic valve so that the distribution destination is the radiator 50. In such a case, for example, a plurality of determination values including a first determination value and a second determination value having a value larger than the first determination value can be used as the predetermined determination value. In this case, the thermostat 60, the electromagnetic valve, and the ECU 1 serve as a flow control device.

In the above-described embodiment, the case where the orifice 70 is incorporated in the sixth cooling water circulation path 86 has been described. This is because the cooling water W can be prevented or suppressed from boiling when warm. However, the present invention is not necessarily limited to this. For example, the orifice 70 can be provided in a portion of the third cooling water circulation path 83 on the downstream side of the water-cooled exhaust manifold 30 and on the front side of the engine body 21. In this case, it is possible to prevent or suppress the boiling of the cooling water W as a result of a rapid increase in the amount of heat received by the water-cooled exhaust manifold 30 during cold weather.
In the above-described embodiment, the case where the orifice 70 is a flow rate adjusting means has been described. However, the present invention is not necessarily limited to this, and the flow rate adjusting means may be, for example, an electronic flow rate adjusting valve. For example, the ECU 1 appropriately controls the flow rate adjusting valve to increase the pressure of the cooling water W in the water-cooled exhaust manifold 30 according to a necessary situation, or the pressure of the cooling water W in the cooling exhaust manifold 30 according to a necessary degree. It is also possible to adjust the size. In controlling the flow rate control valve in this way, the flow rate control valve can be controlled based on, for example, the size of the cooling loss Qw or according to the size of the cooling loss Qw.

Various means such as a detection means, an estimation means, and a control means used when applying the present invention are rationally realized by the ECU 1 that mainly controls the engine 20, but other electronic controls, for example, may be used. It may be realized by hardware such as a device or a dedicated electronic circuit, or a combination thereof. In this regard, the distribution control device according to the present invention can be realized as a module product including a combination of, for example, a thermostat 60 and a dedicated electronic circuit having a function as a control means.

Claims

A refrigerant pumping device for pumping a common refrigerant to a plurality of refrigerant circulation paths;
An engine in which an engine body is incorporated in at least one refrigerant circulation path among the plurality of refrigerant circulation paths;
An exhaust system cooling means that is incorporated in at least one refrigerant circulation path among the plurality of refrigerant circulation paths, has a heat capacity smaller than that of the engine body, and cools the engine exhaust system with a circulating refrigerant;
A cooler which is incorporated in at least one refrigerant circulation path among the plurality of refrigerant circulation paths and cools the circulating refrigerant;
A flow control device that determines whether or not to circulate refrigerant through at least one refrigerant circulation path in which the cooler is incorporated among the plurality of refrigerant circulation paths, based on a predetermined determination value, and controls circulation of the refrigerant. And comprising
The engine cooling apparatus, wherein the predetermined determination value is a determination value related to the amount of heat received by the refrigerant from the exhaust by the exhaust system cooling means.
The engine cooling device according to claim 1,
Among the plurality of refrigerant circulation paths, it is incorporated into at least one refrigerant circulation path in which the exhaust system cooling means is incorporated,
The apparatus further comprises a flow rate adjusting means for adjusting the flow rate of the refrigerant discharged from the exhaust system cooling means so that the pressure of the refrigerant flowing through the exhaust system cooling means is higher than the system pressure of the plurality of refrigerant circulation paths. Engine cooling system.