JP2012215141A - Engine cooling apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect boiling rapidly and accurately when a coolant is boiled in internal passages (13, 14) upon a cold start, in an engine cooling apparatus that allows the coolant to circulate in the internal passages (13, 14) and external passages (21 to 23) as a closed loop using a water pump 4.SOLUTION: A control device 100 brings the internal passages (13, 14) into non-communication with the external passages (21 to 23) upon the cold start, and thereby the internal passages become a closed space. The control device detects the boiling of the coolant in the internal passages (13, 14) on the basis of a pressure of the coolant in the closed space.

Description

  The present invention relates to an engine cooling apparatus in which an internal passage and an external passage of an engine are closed and a coolant can be circulated by a water pump.

  For example, Patent Document 1 describes that in a cooling device for an internal combustion engine including an electric water pump, the level of cooling water is detected, and the boiling of the cooling water is detected based on the rate of increase of the water level. .

  In paragraphs 0019, 0020, 0023, and 0024 of Patent Document 1, a reserve tank is installed above the radiator, a liquid level sensor is installed in the reserve tank, and the liquid level of the reserve tank when the cooling water boils. Since the water level rises rapidly, it is described that this is detected by a liquid level sensor to detect boiling of cooling water.

  This Patent Document 1 does not particularly mention the boiling state, that is, whether it is nucleate boiling or film boiling. Note that nucleate boiling is a unit in which bubbles are generated with the foaming point as a nucleus, and relatively small bubbles are generated. On the other hand, film boiling is a unit in which the temperature rises from the state of nucleate boiling and the number of bubbles increases, and the bubbles merge to form a vapor film that locally covers the heat transfer surface. Will occur.

  Further, for example, in Patent Document 2, an exhaust heat recovery device is installed in a warm-up passage outside the engine, and the cooling water nucleates with the aim of efficiently recovering the heat of the exhaust gas by the exhaust heat recovery device. When this happens, it is detected and the state of nucleate boiling is maintained. The exhaust heat recovery unit is a unit that recovers exhaust heat by exchanging heat between the exhaust gas flowing through the exhaust passage and the cooling water.

  Paragraph 0025 of this Patent Document 2 describes that the nucleate boiling, film boiling, or no boiling of the cooling water in the cooling water circulation path is determined based on the water pressure in the cooling water circulation path and the frequency of the water pressure fluctuation. Yes. A water pressure sensor is installed in the cylinder head of the engine, and the discharge flow rate of the electric pump is controlled so as to maintain nucleate boiling based on the output of the water pressure sensor.

JP 2008-303775 A JP 2008-157090 A

  The above Patent Document 2 has room for improvement in the following points. In other words, in the case of Patent Document 2, since the engine internal passage communicates with the engine external passage and the cooling water is circulated, the pressure fluctuation of the cooling water in the entire cooling water circulation path is detected by the water pressure sensor. It comes to detect. When local nucleate boiling occurs in such a cooling water circulation path, the amount of change in the cooling water pressure in the entire cooling water circulation path with this nucleate boiling is very small. It is thought that it is difficult to distinguish whether is due to nucleate boiling or a noise component. If the nucleate boiling of the cooling water is determined based on the output signal of such a water pressure sensor, it must be said that the detection accuracy of the nucleate boiling is low.

  In view of such circumstances, the present invention provides an engine cooling device in which the internal passage and the external passage of the engine are closed loops so that the coolant can be circulated by a water pump. The coolant in the internal passage boiled during a cold start. Sometimes it aims to make it possible to detect the boiling quickly and accurately.

  The present invention relates to an engine cooling device in which an internal passage and an external passage of an engine are closed and a coolant can be circulated by a water pump, and the internal passage is not communicated with the external passage when the engine is cold-started. And a control device that detects boiling of the coolant in the internal passage based on the pressure of the coolant in the closed space.

  Generally, when the engine is cold-started, the coolant in the internal passage tends to boil with heat generated from the combustion chamber of the engine.

  In the above configuration of the present invention, the internal passage of the engine is closed during cold start, that is, during warm-up, and the internal passage formed as the closed space is monitored by monitoring the pressure fluctuation of the coolant in the closed space. The boiling point of the coolant in is detected. Here, the volume of the closed space is much smaller than the total volume of the entire coolant circulation path (a state in which the external passage is connected to the internal passage). Therefore, the temperature rise and pressure rise of the coolant in the closed space are much faster than the temperature rise and pressure rise of the coolant in the entire coolant circulation path, and the pressure fluctuation range in the closed space is naturally cooled. Compared with the pressure fluctuation range in the whole liquid circulation path, it becomes much larger.

  Since the boiling of the coolant is detected by examining the pressure of the coolant in such a relatively small volume closed space, it becomes easy to distinguish between the pressure fluctuation and the noise component. The determination accuracy when determining the presence or absence of boiling of the coolant based on the pressure value and the frequency of pressure fluctuation is improved. Therefore, it becomes possible to quickly and accurately detect the boiling of the coolant in the internal passage that is a closed space.

  Preferably, the boiling state to be detected is nucleate boiling. In this configuration, after detecting nucleate boiling, for example, if the internal passage and the external passage are communicated with each other so as to suppress an increase in the temperature or pressure of the cooling liquid, it is possible to prevent the film boiling from progressing. It becomes possible.

  Preferably, in the engine cooling apparatus, the external passage includes a circulation passage connected to a coolant discharge port and a coolant introduction port of the internal passage. The first and second valves for changing the coolant flow rate are respectively installed near the outlet, and the control device closes the internal valves by closing both valves during the cold start. A preparation means for making the passage a closed space, a boiling judgment means for judging the presence or absence of boiling of the coolant in the internal passage based on the pressure of the coolant and the pressure fluctuation frequency in the closed space, and boiling by the boiling judgment means It is possible to adopt a configuration including a coping means that opens both the valves when it is determined to be present.

  Here, the external passage is clarified, and a component for making the internal passage a closed space is specified as a valve. In this case, for example, the first and second valves may be installed at least on the upstream side and the downstream side of the internal passage. Therefore, the configuration is simple, which is advantageous in suppressing an increase in equipment cost.

  Preferably, in the engine cooling apparatus, the external passage is connected in parallel to the circulation passage connected to the coolant discharge port and the coolant introduction port of the internal passage, and in parallel to the upstream side of the circulation passage. A radiator passage in which a radiator is installed, and in the circulation passage, first and second valves for changing the coolant flow rate are installed near the introduction port and the discharge port of the internal passage, A third valve for changing the coolant flow rate is installed upstream of the radiator in the radiator passage, and is closed downstream of the radiator in the radiator passage when the coolant is below the warm-up completion temperature. A thermostat that is fully opened when the temperature is equal to or higher than the warm-up completion temperature is set, and the control device is configured to perform the cold start at the cold start. A means for making the internal passage closed by closing all valves, and boiling for determining whether or not the coolant is boiling in the internal passage based on the pressure of the coolant in the closed space and the frequency of pressure fluctuations It can be configured to include a determination unit and a coping unit that opens the first and second valves when the boiling determination unit determines that there is boiling.

  Here, the external passage is specified as a configuration including a circulation passage and a radiator passage, and the arrangement position of the thermostat is specified. In this case, the internal passage is closed by closing all the valves at the cold start. Since the first and second valves are opened when the coolant in the closed space boils, the coolant is circulated using the internal passage and the circulation passage of the engine as a closed loop, and the boiling generated in the internal passage is prevented. Will be lost. Then, as the coolant circulates in the internal passage and the circulation passage, when the coolant on the upstream side of the thermostat reaches the warm-up completion temperature or higher, the thermostat is fully opened. At that time, if the third valve is opened, The heat of the circulated coolant is dissipated by the radiator. Thereby, the temperature of the circulating coolant is kept at the warm-up completion temperature.

  Preferably, in the engine cooling apparatus, the external passage is connected in parallel to the circulation passage connected to the coolant discharge port and the coolant introduction port of the internal passage, and in parallel to the upstream side of the circulation passage. A radiator passage in which a radiator is installed, and an auxiliary passage in which an EGR cooler and an oil cooler are installed in the middle of the internal passage and upstream of the downstream connection portion of the radiator passage with respect to the circulation passage In the circulation passage, first and second valves for changing the amount of coolant flow are installed near the introduction port and the discharge port of the internal passage, respectively, and in the radiator passage more than the radiator A third valve for changing the coolant flow rate is installed on the upstream side, and cooling is provided downstream of the radiator in the radiator passage. A thermostat that is closed when the temperature is lower than the warm-up completion temperature, and is fully opened when the temperature is equal to or higher than the warm-up completion temperature is installed in the auxiliary passage near the downstream connection portion of the circulation passage. A fourth valve for changing the flow rate is installed, and the control device prepares the internal passage in a closed space by closing all the valves during the cold start. Boiling determination means for determining the presence or absence of boiling of the cooling liquid in the internal passage based on the pressure of the cooling liquid in the closed space and the frequency of the pressure fluctuation, and when the boiling determination means determines that the boiling is present, 1 and a coping means for opening the second valve.

  Here, the external passage is specified as a configuration including a circulation passage, a radiator passage, and an auxiliary machinery passage, and it is specified that a valve is installed in each of the thermostat arrangement position, the radiator passage, and the auxiliary passage. In this case, the internal passage is closed by closing all the valves at the cold start. When the coolant in the closed space boils, the first, second and fourth valves are opened, so that the coolant is circulated using the internal passage, the circulation passage and the auxiliary passage of the engine as a closed loop. The boiling that occurred in the passage will be lost. As the coolant circulates in the internal passage, the circulation passage, and the accessory passage, the thermostat is fully opened when the coolant on the upstream side of the thermostat reaches the warm-up completion temperature or higher. If opened, the heat of the circulated coolant is dissipated by the radiator. Thereby, the temperature of the circulating coolant is kept at the warm-up completion temperature.

  The present invention relates to an engine cooling apparatus in which an internal passage and an external passage of an engine are closed loops so that coolant can be circulated by a water pump, and when the coolant in the internal passage boils during cold start, It becomes possible to detect accurately.

  Further, the present invention provides an engine cooling apparatus in which the internal passage and the external passage of the engine are closed loops, and the coolant can be circulated by a water pump. It becomes possible to detect quickly and accurately, and it is possible to quickly complete warm-up while uniformly controlling the temperature.

It is a figure showing the schematic structure of one embodiment of the engine cooling device concerning the present invention. FIG. 2 is a diagram showing a coolant circulation path after detecting nucleate boiling of coolant in an internal passage of the engine in FIG. 1. FIG. 2 is a diagram illustrating a coolant circulation path after engine warm-up is completed in FIG. 1. It is a flowchart used for operation | movement description by the control apparatus of FIG. It is a graph for demonstrating the state of the boiling by the control apparatus of FIG.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  1 to 5 show an embodiment of the present invention. The engine 1 shown in FIG. 1 includes at least a cylinder block 11 and a cylinder head 12. In FIG. 1, the components described on the upper side of the page are the high pressure side, and the components described on the lower side of the page are the low pressure side.

  A water jacket 13 is provided in the cylinder block 11. A water jacket 14 is provided in the cylinder head 12. The block-side water jacket 13 and the head-side water jacket 14 correspond to the internal passage of the engine 1. The coolant is an antifreeze such as an aqueous solution of ethylene glycol.

  The block-side water jacket 13 is opened toward the deck surface of the cylinder block 1, that is, the surface on which the cylinder head (not shown) is assembled. The cylinder block 1 provided with such a water jacket 13 is called a so-called open deck type. The head-side water jacket 14 is opened downward, that is, toward the cylinder block 1 side. That is, the coolant can flow between the cylinder block side water jacket 13 and the cylinder head side water jacket 14. The cylinder block 1 can be a closed deck type.

  In the cylinder block 11, an inlet 15 for introducing a coolant into the block-side water jacket 13 is provided on one end surface in the cylinder arrangement direction. Further, a discharge port 16 for discharging the coolant from the head side water jacket 14 is provided on the other end surface of the cylinder head 12 in the cylinder arrangement direction.

  A circulation passage 21 for introducing the coolant discharged from the head side water jacket 14 into the block side water jacket 13 is connected to the introduction port 15 of the cylinder block 11 and the discharge port 16 of the cylinder head 12. .

  A radiator passage 22 and an accessory passage 23 are further connected to the circulation passage 21. The circulation passage 21, the radiator passage 22 and the auxiliary machinery passage 23 correspond to an external passage of the engine 1.

  A water pump 4 and a heater core 5 are provided in the circulation passage 21. The water pump 4 is provided at a position near the introduction port 15 of the cylinder block 11 in the circulation passage 21.

  Although not shown, the water pump 4 is a mechanical water pump driven by a crankshaft of an engine. Since the use form of this mechanical water pump is the same as a known one, it is not shown in detail, but a belt is wound around the water pump pulley and the crankshaft pulley, and an electromagnetic clutch is attached to the water pump pulley. The electromagnetic clutch is connected and disconnected by the control device 100 to control the water pump 4 to be activated or stopped.

  The heater core 5 is a heat exchanger for heating the interior of the vehicle, and is installed near the discharge port 16 of the cylinder head 12 in the circulation passage 21.

  A radiator 6 is provided in the radiator passage 22. The radiator 6 is a heat exchanger for dissipating the heat of the coolant to the atmosphere. A reserve tank 17 is provided on the upstream side of the radiator 6 in the radiator passage 22. Further, the downstream side of the radiator passage 22 in the coolant flow direction from the radiator 6 is connected between the water pump 4 and the heater core 5 via the thermostat 7 in the circulation passage 21.

  The thermostat 7 has a known configuration and is not shown in detail. However, when the coolant temperature at the thermostat installation location becomes less than the warm-up completion temperature (for example, 80 ° C. to 90 ° C., preferably 82 ° C.) Th, the thermo wax Since the coagulation shrinks and the wax pressure decreases, the valve body automatically closes to reduce the flow of the coolant from the radiator passage 22 to the water pump 4, but the coolant temperature at the location where the thermostat 7 is installed When the temperature reaches the warm-up completion temperature Th or higher, the thermowax is melted and expanded to increase the wax pressure, so that the valve body is automatically fully opened to allow the coolant flow from the radiator passage 22 to the water pump 4. In short, the valve opening temperature of the thermostat 7 is set based on the warm-up completion temperature Th.

  The accessory passage 23 is connected to the middle of the block-side water jacket 13 of the cylinder block 11 and to the upstream side of the downstream connection portion of the radiator passage 22 with respect to the circulation passage 21. This auxiliary machine passage 23 is bifurcated on the upstream side and merges on the downstream side. One branch passage 23a is provided with an EGR cooler 8 and an EGR valve 9, and the other branch passage 23b is provided with an oil cooler. 10 is installed.

  The EGR cooler 8 and the EGR valve 9 are provided in an EGR system for suppressing the generation of NOx by returning a part of the exhaust discharged from the engine 1 to the intake system (not shown) of the engine 1. . The EGR cooler 8 is a heat exchanger that absorbs the heat of the exhaust gas that is returned to the intake system and cools the exhaust gas. The EGR cooler 8 communicates with the coolant that flows through the one branch path 23a of the auxiliary machine passage 23. It is installed in a state that allows heat exchange. The EGR valve 9 adjusts the amount of EGR that returns to the intake passage of the engine 1. The oil cooler 10 exchanges heat between the oil taken out from the engine 1 and the coolant flowing through the other branch passage 23b of the auxiliary passage 23 described above.

  Furthermore, four valves 31 to 34 are provided in the circulation passage 21, the radiator passage 22, and the accessory passage 23.

  Specifically, the first valve 31 is installed near the introduction port 15 of the block-side water jacket 13 in the circulation passage 21, and the second valve 32 is near the discharge port 16 of the head-side water jacket 14 in the circulation passage 21. Is installed. The third valve 33 is installed between the radiator 6 and the reserve tank 17 in the radiator passage 22, and the fourth valve 34 is installed closer to the downstream connection portion with the circulation passage 21 in the auxiliary machinery passage 23. Yes.

  When all these four valves 31 to 34 are closed, the internal passages (13, 14) can be closed. Further, when the third valve 33 is closed, the cooling liquid cannot flow through the radiator passage 22, and when the fourth valve 34 is closed, the cooling liquid cannot flow through the auxiliary passage 23.

  In this embodiment, the first to fourth valves 31 to 34 are, for example, electromagnetic valves, and are configured to be individually opened and closed by the control device 100. However, for example, three of the second to fourth valves 32 to 34 are not shown, but can be configured to be individually opened and closed by using a single switching mechanism.

  Various operations and temperature management of the engine 1 are controlled by the control device 100. The control device 100 is an electronic control unit (ECU), not shown in detail, but a CPU (central processing unit), ROM (program memory), RAM (data memory), and backup RAM (nonvolatile memory). It is set as the well-known structure provided with these.

  The ROM stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU executes arithmetic processing based on various control programs and maps stored in the ROM. The RAM is a memory that temporarily stores calculation results in the CPU, data input from each sensor, and the like. The backup RAM is a nonvolatile memory that stores data to be saved when the engine 1 is stopped. It is memory.

  In this embodiment, a temperature sensor 25 for detecting the temperature of the coolant and a pressure sensor 26 for detecting the pressure of the coolant are provided near the discharge port 16 of the cylinder head 12.

  This temperature sensor 25 outputs a signal corresponding to the temperature of the coolant and inputs it to the control device 100, and the pressure sensor 26 outputs a signal corresponding to the pressure of the coolant and inputs it to the control device 100. Then, the control device 100 recognizes the temperature Tc of the coolant based on the input of the output signal of the temperature sensor 25, and the pressure of the coolant in the internal passages (13, 14) based on the input of the output signal of the pressure sensor 26. And the frequency of the pressure fluctuation, and by collating the recognized pressure and the frequency of the pressure fluctuation with a boiling judgment map prepared in advance, the boiling of the coolant in the internal passages (13, 14) ( In this embodiment, the presence or absence of nucleate boiling is detected.

  The boiling state includes nucleate boiling and film boiling. Note that nucleate boiling is a unit in which bubbles are generated with the foaming point as a nucleus, and relatively small bubbles are generated. On the other hand, film boiling is a unit in which the temperature rises from the state of nucleate boiling and the number of bubbles increases, and the bubbles merge to form a vapor film that locally covers the heat transfer surface. Will occur.

  Considering this point, the map is created so that it is possible to identify whether the boiling state is nucleate boiling or film boiling based on appropriate experimental results. For reference, FIG. 5 shows changes in the pressure of the cooling liquid when the cooling liquid undergoes nucleate boiling or film boiling in a state where the internal passages (13, 14) are closed spaces. When the pressure is substantially constant as shown in period A in FIG. 5 but the pressure fluctuates greatly in a short time, it indicates a state of not boiling, and the pressure is almost as shown in period B in FIG. When the pressure fluctuation amplitude is constant, the nucleate boiling state is indicated, and when the pressure gradually increases with time as shown in the period C of FIG. 5, the film boiling occurs. It shows the state. The map is created using this data.

  For example, the control device 100 performs various control relating to the operation of the engine 1 and also performs temperature adjustment control of the engine 1 as described below.

  Next, the temperature adjustment control of the engine 1 by the control device 100 will be described with reference to the flowchart shown in FIG.

  When the engine 1 is started, the control device 100 starts executing the processing of the flowchart shown in FIG. First, it is checked in step S1 whether the engine 1 has been cold started. That is, in this step S1, the temperature Tc of the coolant discharged from the discharge port 16 of the cylinder head 12 is detected based on the input of the output signal from the temperature sensor 25, and this detected value Tc is less than the warm-up completion temperature Th. It is determined whether or not.

  If Tc ≧ Th, that is, if it is not a cold start, a negative determination is made in step S1, and the process exits this flowchart. However, if Tc <Th, that is, if it is a cold start, an affirmative determination is made in step S1, and the process proceeds to the subsequent step S2.

  In step S2, all four valves 31 to 34 are closed. In this case, the internal passages (13, 14) and the external passages (21 to 23) of the engine 1 are not communicated, and the internal passages (13, 14) are completely closed. When the valves 31 to 34 are closed in this manner, even if the water pump 4 is driven by the start of the engine 1, the coolant is transferred between the internal passages (13, 14) and the external passages (21 to 23). Since the water cannot be physically circulated, the water pump 4 is idled.

  In subsequent step S3, it is determined whether or not the coolant in the internal passages (13, 14) of the engine 1 is nucleate boiling. Here, based on the input of the output signal from the pressure sensor 26, the actual coolant pressure and the frequency of the pressure fluctuation in the internal passages (13, 14) made into the completely closed space are recognized and recognized. It is determined whether or not the coolant is nucleate-boiling by comparing the result with the boiling determination map.

  At this time, the volume of the closed space is about 1/3 of the total volume of the entire coolant circulation path (in a state where the internal passages (13, 14) and the external passages (21 to 23) are communicated). And much smaller. However, the total volume and the volume of the closed space appropriately vary according to the displacement of the engine 1 and the type and number of auxiliary equipment attached to the engine 1. Therefore, the temperature rise and pressure rise of the coolant in the small volume closed space are much faster than the temperature rise and pressure rise of the coolant in the entire coolant circulation path, and the pressure fluctuation range in the closed space As a matter of course, the pressure fluctuation width in the entire coolant circulation path is significantly larger.

  The pressure of the coolant in such a relatively small volume closed space is detected by the pressure sensor 26, and the nucleate boiling of the coolant in the internal passages (13, 14) is detected based on the output signal of the pressure sensor 26. As a result, it is easy to distinguish between pressure fluctuations and noise components, and accordingly, the accuracy of determination when determining the presence or absence of nucleate boiling of the coolant by comparing the actual recognition result with the map is improved. Become. Therefore, it becomes possible to detect the nucleate boiling of the coolant in the internal passages (13, 14) quickly and accurately.

  If the coolant in the internal passages (13, 14) is not nucleate boiling, that is, if a negative determination is made in step S3, the process returns to step S3 and waits for the coolant to nucleate. When the coolant in the internal passages (13, 14) nucleates, that is, when an affirmative determination is made in step S3, the process proceeds to the subsequent step S4.

  In step S4, the valves 31, 32 and 34 are opened. As a result, the internal passages (13, 14) are communicated with the circulation passage 21 and the auxiliary passage 23, so that the coolant is circulated without passing through the radiator 6, and this circulating cooling is performed. The liquid temperature gradually rises.

  Next, in step S5, it is determined whether or not the temperature Tc of the coolant discharged from the discharge port 16 of the cylinder head 12 is equal to or higher than the warm-up completion temperature Th. Here, the coolant temperature Tc is detected based on the input of the output signal from the temperature sensor 25, and this detection value Tc can be determined by comparing the warm-up completion temperature Th.

  Here, when Tc <Th, that is, when the warm-up is not completed, a negative determination is made in step S5, and the process returns to step S5. That is, the coolant temperature Tc is raised by continuing the state in which the coolant is circulated between the internal passages (13, 14) and the circulation passage 21 and the auxiliary passage 23. When Tc ≧ Th and warming up is completed, an affirmative determination is made in step S5, and the process proceeds to the subsequent step S6.

  In step S6, the third valve 33 is opened. Thus, the coolant discharged from the discharge port 16 of the cylinder head 12 to the circulation passage 21 is also circulated through the radiator passage 22 and passes through the radiator 6, and then enters the circulation passage 21 via the thermostat 7. Will come back. In the cooling liquid circulation process in this state, the cooling liquid recovers the heat of the cylinder head 12 and the cylinder block 11 and is dissipated to the atmosphere by the radiator 6, so that the temperature of the circulating cooling liquid is increased. The machine completion temperature Th is maintained.

  Thereafter, returning to step S1, the temperatures of the engine 1 and the coolant are adjusted to be constant.

  As described above, in the embodiment to which the present invention is applied, the internal passage (block-side water jacket 13, head-side water jacket 14) and the external passage (circulation passage 21, radiator passage 22, auxiliary machinery passage 23) of the engine 1 In the engine 1 in which the coolant can be circulated by the water pump 4 in a closed loop, the nucleate boiling is quickly and accurately detected when the coolant nucleates in the internal passages (13, 14) of the engine 1 during warm-up. In addition, the warm-up of the engine 1 can be quickly completed while the temperature is uniformly controlled.

  In particular, in this embodiment, after detecting the nucleate boiling, for example, by opening the valves 31, 32, 34 in step S4, the internal passages (13, 14) and the external passages (21-23) are communicated. Since measures are taken to suppress an increase in the temperature and pressure of the coolant, it is possible to prevent film boiling from occurring in the closed space, that is, the internal passages (13, 14). Incidentally, if film boiling occurs in the closed space, an excessive heat load is applied to the engine 1. Therefore, if the nucleate boiling occurs in the closed space, it is not necessary to apply an excessive heat load to the engine 1. It becomes like this. Therefore, when the measures are taken as described above, the time during which the engine 1 is in the closed space during the cold start (the cooling liquid circulation stop time) is maximized within a range in which an excessive heat load is not applied to the engine 1. Therefore, the heat transfer rate from the engine 1 to the coolant can be increased in the nucleate boiling region. As a result, the warm-up time can be shortened as much as possible, and the effect that the fuel consumption can be improved can be obtained.

  In addition, when the internal passages (13, 14) of the engine 1 are closed, first and second valves 31, 32 are installed in the circulation passage 21 near the discharge port 16 and the introduction port 15 of the cylinder head 12. Therefore, it is advantageous in reducing the equipment cost of the engine cooling device. In addition, when the radiator passage 22 and the auxiliary machinery passage 23 are provided as external passages as in this embodiment, the third valve 33 and the fourth valve 34 are further provided. Since the valves 31 to 34 can use commercially available general-purpose products, the engine cooling device can be configured relatively simply and inexpensively. Therefore, the engine cooling device can be configured at a relatively low cost, and warm-up can be completed quickly while uniformly controlling the temperature, thereby contributing to improvement in fuel consumption of the engine 1.

  The correspondence relationship between the constituent elements described in the embodiment described above and the constituent elements described in the claims will be described. Since each step of the flowchart shown in FIG. 4 is a function realization means by the control device 100, the preparation means described in the claims corresponds to steps S1 and S2 in FIG. 4, and the boiling determination means described in the claims is the same as FIG. And the coping means described in the claims corresponds to step S4 in FIG.

  In addition, this invention is not limited only to the said embodiment, It can change suitably in the range equivalent to the claim and the said range.

  (1) Although the example which installed four valves 31-34 is given in the said embodiment, this invention is not limited to this, The 1st installed in the circulation path 21 in the said embodiment. The valve 31 can be eliminated. In that case, if the second to fourth valves 32 to 34 are closed during the cold start of the engine 1, the water pump 4 will idle even if it is driven, so the second to fourth valves 32 to 34 are closed. Thus, the internal passages (13, 14) can be closed.

  (2) Although the example using the mechanical water pump 4 is given in the above embodiment, the present invention is not limited to this, and for example, an electric water pump can be used. In this case, the same operation and effect as the above embodiment can be obtained.

  (3) In the above embodiment, an example in which the circulation passage 21, the radiator passage 22, and the auxiliary machinery passage 23 are provided as external passages is given. However, the present invention is not limited to this, and for example, an auxiliary passage. The machine passage 23 can be eliminated.

  (4) In the above embodiment, an example in which nucleate boiling is used as the state of boiling to be detected is given, but the present invention is not limited to this. For example, the state of boiling to be detected is film boiling. Is possible.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for an engine cooling device in which an internal passage and an external passage of an engine are closed loops and coolant can be circulated by a water pump.

1 Engine 11 Cylinder block 12 Cylinder head 13 Block side water jacket (internal passage)
14 Head side water jacket (internal passage)
15 Block side water jacket inlet 16 Head side water jacket outlet 4 Water pump 5 Heater core 6 Radiator 7 Thermostat 21 Circulation path (external path)
22 Radiator passage (external passage)
23 Auxiliary machinery passage (external passage)
25 Temperature Sensor 26 Pressure Sensor 31 First Valve 32 Second Valve 33 Third Valve 34 Fourth Valve 100 Control Device

Claims (5)

An engine cooling apparatus in which an internal passage and an external passage of the engine are closed loops and coolant can be circulated by a water pump,
A control device for detecting a boiling of the coolant in the internal passage based on the pressure of the coolant in the closed space by making the internal passage out of communication with the external passage when the engine is cold started An engine cooling device characterized by comprising: The engine cooling device according to claim 1, wherein
The engine cooling apparatus according to claim 1, wherein the boiling state to be detected is nucleate boiling. The engine cooling device according to claim 1 or 2,
The external passage includes a circulation passage connected to a coolant discharge port and a coolant introduction port of the internal passage, and in this circulation passage, a coolant circulation is provided near the introduction port and the discharge port of the internal passage, respectively. First and second valves for changing the amount are installed,
The control device is configured to prepare the internal passage to be closed by closing both valves during the cold start, and to cool the internal passage based on the pressure of the coolant and the frequency of pressure fluctuation in the closed space. An engine cooling apparatus comprising: boiling determining means for determining the presence or absence of boiling of the liquid; and countermeasure means for opening both valves when the boiling determining means determines that there is boiling. The engine cooling device according to claim 1 or 2,
The external passage includes a circulation passage connected to the coolant discharge port and the coolant introduction port of the internal passage, and a radiator passage connected in parallel to the upstream side of the circulation passage and having a radiator installed in the middle thereof. Prepared,
In the circulation passage, first and second valves for changing the coolant flow rate are installed near the introduction port and the discharge port of the internal passage, respectively, and upstream of the radiator in the radiator passage. A third valve for changing the coolant flow rate is installed, and the downstream side of the radiator in the radiator passage is closed when the coolant is lower than the warm-up completion temperature, while the warm-up completion temperature is exceeded. A thermostat that is fully open at the time of
The control device includes a preparation means for closing the internal passage by closing all the valves during the cold start, and a pressure of the coolant in the closed space and a frequency of pressure fluctuation in the internal passage. An engine cooling apparatus comprising: boiling determination means for determining the presence or absence of boiling of the coolant; and countermeasure means for opening the first and second valves when the boiling determination means determines that there is boiling. The engine cooling device according to claim 1 or 2,
The external passage includes a circulation passage connected to the coolant discharge port and the coolant introduction port of the internal passage, a radiator passage connected in parallel to the upstream side of the circulation passage, and a radiator installed on the way, An auxiliary machine passage that is connected to the middle of the internal passage and to the upstream side of the downstream connection portion of the radiator passage with respect to the circulation passage, and in the middle of which an EGR cooler and an oil cooler are installed,
In the circulation passage, first and second valves for changing the coolant flow rate are installed near the introduction port and the discharge port of the internal passage, respectively, and upstream of the radiator in the radiator passage. A third valve for changing the coolant flow rate is installed, and the downstream side of the radiator in the radiator passage is closed when the coolant is lower than the warm-up completion temperature, while the warm-up completion temperature is exceeded. A thermostat that is fully open at the time of installation, a fourth valve for changing the coolant flow rate is installed near the downstream side connection portion of the circulation passage in the auxiliary passage,
The control device includes a preparation means for closing the internal passage by closing all the valves during the cold start, and a pressure of the coolant in the closed space and a frequency of pressure fluctuation in the internal passage. An engine cooling apparatus comprising: boiling determination means for determining the presence or absence of boiling of the coolant; and countermeasure means for opening the first and second valves when the boiling determination means determines that there is boiling.

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