JP2013015070A - Engine cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve responsiveness of opening and closing a large flow valve 23, while achieving a reduction of equipment cost, in an engine cooling device having a water jacket 2, a circulation passage 3 outside an engine 1, first and second bypass passages 21, 22, the large flow valve 23, and a small flow valve 24.SOLUTION: The large flow valve 23 is a thermostat. A coolant inflow side of the first bypass passage 21 is connected to a part closer to an outlet 2a of the water jacket 2 rather than a radiator 15 in a radiator passage 4. The coolant inflow side of the second bypass passage 22 is connected to a part closer to a coolant inflow part of the large flow valve 23 in the first bypass passage 21.

Description

  The present invention is a mode in which the coolant is taken out from the water jacket of the engine and cooled by the radiator and then returned to the water jacket, and the coolant is taken out from the water jacket of the engine and bypassed from the radiator to flow into the circulation path. The present invention relates to an engine cooling device capable of executing a configuration for returning to a water jacket. The engine cooling device includes first and second bypass passages for allowing the water jacket coolant to flow into the circulation path, bypassing the radiator, and a large flow valve installed in the first bypass passage; A small flow valve installed in the second bypass passage is provided.

  For example, in Patent Document 1, a bypass (cooling water passage) is connected to a water jacket of an engine, an exhaust heat recovery device, a water pump, and a heater core are installed in the circulation passage, and a bypass passage that bypasses the engine in the circulation passage. And a radiator passage in which a radiator is installed is described.

  In addition, a three-way valve is installed at the junction of the discharge side of the water jacket of the engine, the circulation path, and the bypass path. This three-way valve not only secures a cold coolant flow route for stopping the coolant circulation in the water jacket and circulating the coolant between the bypass passage and the circulation passage, but also stops the coolant circulation in the bypass passage to prevent the water from flowing. A hot water route for circulating the coolant between the jacket and the circulation path is secured.

  Further, a thermostat is installed at a connection portion between the radiator passage and the circulation passage. This thermostat is opened when the temperature of the coolant flowing through the circulation path becomes high, so that the coolant flows from the water jacket to the circulation path through the radiator passage, while the cooling flowing through the circulation path is performed. When the temperature of the liquid is low, the valve is closed to stop the flow of the cooling liquid from the water jacket to the circulation path through the radiator passage.

  As the operation of this Patent Document 1, the cold cooling water route is secured by a three-way valve when the engine is cold started. As a result, the coolant flow in the water jacket of the engine is stopped, so that warm-up of the engine is promoted.

  When the engine is warmed up, the thermostat is opened, and the hot water route is secured with a three-way valve. As a result, the coolant flows from the water jacket to the radiator passage and is cooled, and the coolant is recirculated from the circulation path to the water jacket, thereby preventing overheating of the engine.

  By the way, in the case of this patent document 1, heating (use of a heater) of a vehicle interior can be performed even while the engine is warming up. In other words, when heating is requested by the driver, the temperature of the coolant is raised by the heat recovered by the exhaust heat recovery device by circulating the coolant between the bypass path and the circulation path, and the air is blown to the heater core by the heater blower. The hot air discharged from the heater core to the atmosphere is supplied into the vehicle compartment by blowing air.

  Furthermore, as described in paragraphs 0073-0078 of Patent Document 1, for example, when switching from the Cold cooling water route to the Hot cooling water route upon completion of engine warm-up, if it is not under heating, Although the cooling water route is switched, in order to suppress the sudden change in the temperature of the coolant flowing into the heater core during heating, the three-way valve is switched to the hot cooling water route after being set to the intermediate temperature mode for a predetermined time. The intermediate temperature mode is a state in which the three-way valve mixes the coolant discharged from the water jacket and the coolant flowing in the bypass passage.

JP 2009-150266 A

  In the above-mentioned Patent Document 1, switching is performed between the Cold cooling water route, the Hot cooling water route, and the intermediate temperature mode by using the three-way valve and the control device. The switching operation is controlled by this control device. There is a concern that the three-way valve has a higher equipment cost than a case where, for example, two electromagnetic valves (open / close valves) are used as an alternative.

  In view of such circumstances, the present invention provides first and second bypass passages for allowing water jacket coolant to flow into the circulation passage by bypassing the radiator, and a large flow valve installed in the first bypass passage. And a small flow valve installed in the second bypass passage, the large flow valve is a thermostat to improve the opening / closing response of the large flow valve while reducing the equipment cost. The goal is to make it possible.

  The engine cooling device according to the present invention is configured to circulate the coolant for the engine water jacket so that the coolant is taken out and then returned to the outside, and to allow the coolant for the water jacket to flow into the circulation path after passing through the radiator. Radiator passages, first and second bypass passages for allowing the coolant in the water jacket to bypass the radiator and flow into the circulation path, a large flow valve installed in the first bypass passage, A small flow valve installed in the second bypass passage, wherein the large flow valve is a thermostat, and the coolant inflow side of the first bypass passage is closer to the outlet of the water jacket than the radiator in the radiator passage. The coolant inflow side of the second bypass passage is connected to the first bypass passage in the first bypass passage. Is connected to a cooling liquid inlet portion side of the flow valve is characterized in that.

  The thermostat means a temperature sensing type automatic operation valve in the automobile related industry. The large flow valve composed of such a thermostat automatically opens and closes based on the coolant temperature upstream in the coolant flow direction.

  In this configuration, although the large flow valve and the small flow valve are provided, the large flow valve is used as a relatively inexpensive general-purpose thermostat, and the small flow valve is replaced with, for example, a relatively inexpensive solenoid valve. This is advantageous in reducing equipment costs.

  In the case of the above configuration, when the small flow valve is opened while the large flow valve is closed, the coolant in the water jacket passes through the second bypass passage to the motor circulation path. Inflow. At this time, the coolant flowing through the second bypass passage flows in the first bypass passage closer to the coolant inflow portion of the large flow valve made of the thermostat, and the temperature sensing of the large flow valve made of the thermostat. It becomes easy to touch the part. As a result, it becomes possible for the temperature sensing part of the large flow valve to sense the temperature change of the coolant flowing through the second bypass passage as quickly as possible, so that the open / close response of the large flow valve is improved. Result.

  Preferably, a water pump and a heater core are installed in the circulation path. In this case, the coolant is circulated by operating the water pump. When the coolant is circulated in this manner, the heater core can release the heat of the coolant to the outside, so that the vehicle interior can be heated by supplying this heat into the vehicle interior.

  Preferably, the engine cooling device further includes a control device for controlling the opening / closing operation of the small flow valve, and the control device controls the small flow valve when the coolant temperature of the water jacket is equal to or higher than a predetermined value. It can be set as the structure which opens a valve.

  Here, the conditions for opening the small flow valve are specified. And the said control apparatus opens the said small flow valve, when the coolant temperature of a water jacket is more than predetermined value. As a result, the coolant of the water jacket flows into the circulation path through the second bypass passage.

  Preferably, the control device may be configured to recognize the coolant temperature of the water jacket by estimating the coolant temperature in a region where the coolant temperature is highest in the water jacket.

  In general, the temperature of the water jacket does not rise as a whole as the engine starts, but the coolant present in the vicinity of the combustion chamber in the water jacket is more likely to be heated than the coolant present in other parts. Further, in a multi-cylinder engine, in general, the coolant present in the region closer to the center in the cylinder arrangement direction in the water jacket is more likely to rise in temperature than the coolant present in other regions. Therefore, the region near the center in the cylinder arrangement direction in the water jacket corresponds to the region where the coolant temperature is highest in the water jacket.

  Here, as a form for recognizing the coolant temperature of the water jacket, an estimated value is recognized rather than a measured value based on a detection output from a temperature sensor or the like. The reason for this is that when the region where the coolant temperature is highest in the water jacket is a region closer to the center in the cylinder arrangement direction in the water jacket, it is difficult to install a temperature sensor in this region. There are many cases. In consideration of this, it can be said that it is practically advantageous to adopt a form in which the estimated value is recognized as described above.

  Preferably, a thermostat is installed downstream of the radiator in the radiator passage, and the thermostat opens when the coolant temperature in the circulation path is equal to or higher than the engine warm-up completion temperature. The coolant is brought into a state of flowing into the circulation path through the radiator passage.

  In this configuration, when the coolant temperature in the circulation path becomes equal to or higher than the engine warm-up completion temperature (thermostat opening temperature), the thermostat automatically opens. As a result, the coolant in the water jacket flows into the circulation path through the radiator and the radiator passage.

  The thermostat means a temperature sensing type automatic operation valve in the automobile related industry. When such a thermostat is used, an engine water temperature sensor and a control system are unnecessary, and it is possible to suppress an unnecessary increase in equipment cost.

  The present invention includes first and second bypass passages for allowing water jacket coolant to flow into a circulation path by bypassing a radiator, a large flow valve installed in the first bypass passage, and the second bypass passage. In the engine cooling device provided with a small flow valve installed in the engine, it is possible to improve the open / close responsiveness of the large flow valve while reducing the equipment cost by using the large flow valve as a thermostat.

It is a figure showing the schematic structure of one embodiment of the engine cooling device concerning the present invention. It is a figure for demonstrating schematic structure of the control system of the engine cooling device of FIG. FIG. 2 is a view for explaining a coolant flow path after completion of warming up of the engine in FIG. 1. FIG. 2 is a view for explaining a coolant flow path when a small flow valve is opened in the middle of warming up of the engine in FIG. 1. FIG. 2 is a diagram for explaining a coolant flow path when a large flow valve is opened in the middle of warming up of the engine in FIG. 1. It is a graph which shows a mode that the coolant temperature of the large flow valve vicinity changes with progress in relation to operation | movement of the small flow valve and large flow valve of FIG. It is a figure which shows schematic structure of the comparative example of the engine cooling device which concerns on this invention.

  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 6 show an embodiment of the present invention. In the figure, 1 is an engine. A water jacket 2 is provided inside the engine 1.

  A throttle valve 6 for adjusting the intake air amount of the engine 1 is provided in the intake passage of the engine 1. The operation of the throttle motor 7 for changing the opening degree of the throttle valve 6 is controlled by an engine electronic control unit (hereinafter referred to as E / G_ECU) 100 described below.

  The water jacket 2 is provided in each of the cylinder block and the cylinder head, and a plurality of portions are connected to each other. The coolant outlet 2a of the water jacket 2 is installed on the cylinder head side, and the coolant inlet 2b of the water jacket 2 is installed on the cylinder block side.

  A closed-loop circulation path 3 is provided outside the engine 1. The circulation path 3 is connected to the water jacket 2 of the engine 1 via a radiator passage 4 and a reflux path 5 so that the coolant can be circulated between the water jacket 2 and the circulation path 3 as necessary. It has become. The coolant flowing through the water jacket 2, the circulation path 3, the radiator path 4, and the reflux path 5 is an antifreeze such as an aqueous solution of ethylene glycol.

  In the middle of the circulation path 3, a water pump 11, a heater core 12, and the like are installed.

  The water pump 11 is installed at a position near the reflux path 5 in the circulation path 3. The water pump 11 is installed in the upstream region 3 a from the connection portion with the radiator passage 4 to the connection portion with the reflux passage 5 in the circulation passage 3. The water pump 11 is electrically operated, and its operation is controlled by the E / G_ECU 100.

  The heater core 12 is a heat exchanger for exchanging heat between the coolant flowing through the circulation path 3 and the atmosphere. The heater core 12 is installed in the downstream region 3 b from the connection portion with the reflux passage 5 to the connection portion with the radiator passage 4 in the circulation passage 3. The heat released from the heater core 12 to the atmosphere is supplied to the vehicle interior by operating the heater blower 13 to heat the vehicle interior. The operation of the heater blower 13 is controlled by an electronic control unit (hereinafter referred to as A / C_ECU) 200 for an air conditioner described below.

  The radiator passage 4 is connected to the downstream side in the coolant flow direction from the heater core 12 in the discharge port 2a of the water jacket 2 and the downstream region 3b of the circulation path 3. A radiator 15 is installed in the middle of the radiator passage 4. The radiator 15 is a heat exchanger for exchanging heat between the coolant flowing through the radiator passage 4 and the atmosphere. The radiator passage 4 is a flow path for allowing the coolant in the water jacket 2 of the engine 1 to flow through the radiator 15 and then to flow downstream from the heater core 12 in the coolant flow direction in the downstream region 3 b of the circulation path 3. .

  The reflux path 5 is connected to the inlet 2 b of the water jacket 2 and the downstream side of the water pump 11 in the coolant flow direction in the circulation path 3. The reflux path 5 is a flow path for allowing the coolant to flow from the circulation path 3 to the inlet 2 b of the water jacket 2.

  Further, a radiator thermostat 16 is installed downstream of the radiator 15 in the radiator passage 4. Since the configuration of the radiator thermostat 16 is the same as a known configuration, a detailed illustration and description thereof are omitted, but generally, a valve body and a thermoactuator are provided. The thermoactuator includes a temperature sensing portion filled with thermowax, and a plunger that is provided in the temperature sensing portion and displaces the valve body to the open side or the close side.

  As the operation of this thermostat, when the coolant temperature thw3 on the upstream side in the coolant flow direction of the temperature sensing portion of the radiator thermostat 16 in the circulation path 3 is lower than a predetermined valve opening start temperature X1 (for example, 82 ° C.), Since the thermox is coagulated and contracted to reduce the wax pressure, the plunger is drawn into the temperature sensing portion and the valve body is displaced to the fully closed position. On the other hand, when the coolant temperature thw3 exceeds the valve opening start temperature X1, the thermowax is gradually melted and expanded, so that the wax pressure gradually increases, so that the plunger gradually protrudes from the temperature sensing portion. The valve body will be opened for the first time. When the coolant temperature thw3 becomes equal to or higher than a predetermined fully open temperature X2 (engine warm-up completion temperature, for example, 88 ° C.), the plunger protrudes from the temperature sensing portion to the outermost position and displaces the valve body to the fully open position. Even when the radiator thermostat 16 is fully closed, the coolant always flows from the heater core 12 of the circulation path 3 to the water pump 11.

  Further, first and second bypass passages 21 and 22 are connected in parallel to the radiator passage 4 upstream of the radiator 15 in the coolant flow direction and the downstream region 3b of the circulation passage 3. The first and second bypass passages 21 and 22 bypass the radiator 15 from the coolant of the water jacket 2 of the engine 1 and flow into the downstream side region 3b of the circulation path 3 upstream of the heater core 12 in the coolant circulation direction. It is a channel for making it happen. A large flow valve 23 is installed in the middle of the first bypass passage 21, and a small flow valve 24 is installed in the middle of the second bypass passage 22.

  Specifically, the coolant inflow side (or the upstream side in the coolant flow direction) of the first bypass passage 21 is connected to the radiator passage 4 closer to the discharge port 2 a of the water jacket 2 than the radiator 15. The coolant inflow side (or the upstream side in the coolant flow direction) of the second bypass passage 22 is connected to the coolant inflow portion of the large flow valve 23 in the first bypass passage 21. The coolant discharge side (or the downstream side in the coolant flow direction) of the first and second bypass passages 21 and 22 is connected to the upstream side in the coolant flow direction from the heater core 12 in the downstream region 3b of the circulation path 3, respectively. ing.

  The E / G_ECU 100 is called an engine control computer for controlling various operations of the engine 1, for example. Although not shown in detail, the E / G_ECU 100 has a known configuration including a CPU (central processing unit), a ROM (program memory), a RAM (data memory), a backup RAM (nonvolatile memory), and the like. The

  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.

  The E / G_ECU 100 performs at least the operations of the electric water pump 11 and the small flow rate valve 24 based on the detection output inputs of the engine water temperature sensor 31 and the heater water temperature sensor 32 in order to adjust the temperature of the engine 1. Control. The engine water temperature sensor 31 is installed in the vicinity of the outlet 2a of the water jacket 2 of the engine 1 and detects the coolant temperature at the installation location (hereinafter simply referred to as the coolant temperature thw1 of the water jacket 2). Further, the heater water temperature sensor 32 is installed in the circulation path 3 on the upstream side of the heater core 12 in the coolant flow direction, and the coolant temperature at the installation location (hereinafter simply referred to as the coolant temperature thw2 of the circulation path 3). Is detected.

  The A / C_ECU 200 is called, for example, a control computer for an air conditioner for controlling the air conditioning operation in the vehicle interior. Although not shown in detail, the A / C_ECU 200 includes a CPU (Central Processing Unit), a ROM (Program Memory), a RAM (Data Memory), a backup RAM (Non-volatile Memory), etc., as with the E / G_ECU 100. It is a known configuration.

  The A / C_ECU 200 receives output signals from the heater switch 41 and the changeover switch 42 installed in the vehicle compartment. The heater switch 41 is turned on and off by the driver in order to execute or stop heating. The changeover switch 42 is pushed by the driver to switch between large (strong) and small (weak) heating capacity.

  The A / C_ECU 200 inputs a signal for operating the heater blower 13 to the E / G_ECU 100 when the driver is requested to perform heating by turning on the heater switch 41 by the driver. 13 is activated. When the heater blower 13 is activated, heat released from the heater core 12 to the atmosphere is supplied into the vehicle compartment. Further, the A / C_ECU 200 inputs a signal for controlling the operating capacity of the heater blower 13 to the E / G_ECU 100 when the execution of the heating capacity switching process is requested by the driver pressing the changeover switch 42. Thus, the operation capability of the heater blower 13 is made to correspond to the request by the E / G_ECU 100.

  Here, a basic operation when the engine 1 is cold started will be described.

  When the engine 1 is cold-started, that is, when the coolant temperature thw3 in the vicinity of the radiator thermostat 16 is lower than the valve opening start temperature X1 when the engine 1 is started, the radiator thermostat 16 is closed. Then, the coolant circulation of the water jacket 2 of the engine 1 is stopped. As a result, the coolant in the engine 1 and the water jacket 2 rises in temperature relatively early due to the heat in the combustion chamber of the engine 1.

  Then, when the coolant temperature thw3 in the vicinity of the radiator thermostat 16 in the circulation path 3 is equal to or higher than the fully open temperature (engine warm-up completion temperature) X2, the radiator thermostat 16 is fully opened. By operating with an appropriate capacity, the coolant in the water jacket 2 of the engine 1 is cooled by passing through the radiator passage 4 and the radiator 15 and then flows into the circulation path 3 as indicated by the arrows in FIG. A part of the coolant circulating in the circulation path 3 is returned to the water jacket 2 of the engine 1 through the reflux path 5. In this way, the coolant temperature thw1 of the water jacket 2 and the coolant temperature thw2 of the circulation path 3 are maintained within a predetermined temperature range.

  By the way, during the warm-up of the engine 1, execution of a process for circulating the coolant between the water jacket 2 and the circulation path 3 through the first bypass path 21 or the second bypass path 22 may be required.

  An example of a situation where execution of such a circulation process is required will be described.

  For example, in a state where the coolant circulation of the water jacket 2 is stopped as during the warm-up operation of the engine 1, the coolant is boiled locally (in the vicinity of the cylinder head combustion chamber) of the water jacket 2. If. When the occurrence of this situation is detected, execution of the circulation process is required to eliminate the boiling.

  The boiling detection is performed by estimating the maximum value of the coolant temperature in the maximum temperature reaching region in the cylinder head in the water jacket 2 every predetermined period (several milliseconds to several tens of milliseconds) after the engine 1 is started. Do.

  As an example of this estimation method, a process of recognizing an initial value of the coolant temperature thw1 of the water jacket 2 based on a detection output from the engine water temperature sensor 31 at the start of the engine 1, and a process after starting the engine 1 A process for calculating the amount of heat generated by the engine 1, a process for calculating an increase value of the maximum temperature reaching region in the cylinder head by the generated heat amount, and adding this increase value to the previous estimated value (the initial value is the initial value). To estimate the current coolant temperature in the cylinder head maximum temperature reaching region, and to determine that boiling occurs when the estimated value exceeds a predetermined value (for example, 96 ° C.). And do.

  In this embodiment, the small flow valve 24 is a normally closed solenoid valve, and the large flow valve 23 is a thermostat.

  The E / G_ECU 100 controls the opening / closing operation of the small flow valve 24 made of an electromagnetic valve. Specifically, the E / G_ECU 100 is opened when the solenoid of the small flow valve 24 is energized, and is closed when the energization of the solenoid is stopped.

  Since the configuration of the large flow valve 23 made of a thermostat is generally the same as a known configuration, a detailed illustration and explanation are omitted, but a valve body and a thermoactuator are provided. The thermoactuator is provided with a temperature sensing portion filled with thermowax for sensing the coolant temperature thw4 on the coolant inflow side of the large flow valve 23, and provided in the temperature sensing portion to open or close the valve body And a plunger to be displaced.

  As the operation of this thermostat, when the coolant temperature thw4 in the vicinity of the temperature sensing portion is lower than a predetermined valve opening start temperature Y1 (for example, 70 ° C.), the thermowax is solidified and contracted and the wax pressure is lowered. The plunger is pulled into the temperature sensing part and the valve body is displaced to the fully closed position. On the other hand, when the coolant temperature thw4 in the vicinity of the temperature sensing part exceeds the valve opening start temperature Y1, the thermowax gradually melts and expands, so that the wax pressure gradually increases. The valve body starts to pop out gradually from the part and starts to open. When the coolant temperature thw4 in the vicinity of the temperature sensing part becomes equal to or higher than a predetermined full opening temperature Y2 (for example, 78 ° C.), the plunger jumps out from the temperature sensing part to the outermost position and displaces the valve body to the full opening position.

  The E / G_ECU 100 opens the small flow valve 24 when the execution of the circulation process is requested, that is, when boiling is detected. As a result, as shown by the arrows in FIG. 4, the circulation path 3 is cooled from the water jacket 2 through the upstream portion of the radiator passage 4, the upstream portion of the first bypass passage 21, and the second bypass passage 22. The liquid is introduced, and a part of the cooling liquid circulating in the circulation path 3 is returned to the water jacket 2 through the reflux path 5.

  At this time, the circulation amount of the cooling liquid is relatively small in accordance with the fully opened capacity of the small flow rate valve 24. Therefore, as shown in FIG. 6, near the temperature sensing portion of the large flow rate valve 23 made of a thermostat. The coolant temperature thw4 rises relatively slowly.

  Thus, when the coolant temperature thw4 in the vicinity of the temperature sensing portion of the large flow valve 23 becomes equal to or higher than the valve opening start temperature Y1, the large flow valve 23 starts to open. As a result, as shown by the arrows in FIG. 5, the coolant flows into the circulation path 3 from the water jacket 2 through a part of the upstream side of the radiator passage 4, the first bypass passage 21 and the second bypass passage 22. Become. For this reason, the circulating amount of the coolant is gradually increased, and the temperature of the circulating coolant is further increased.

  Accordingly, as shown in FIG. 6, when the coolant temperature thw4 in the vicinity of the temperature sensing portion of the large flow valve 23 becomes equal to or higher than the full open temperature Y2, the large flow valve 23 is fully opened, so that the circulation of the coolant is performed. As the amount further increases, the circulating coolant temperature rises relatively quickly.

  For reference, for example, as shown in FIG. 7, the case where the coolant inflow sides of the first bypass passage 21 and the second bypass passage 22 are connected in parallel to the upstream side of the radiator 15 in the radiator passage 4 is compared. For example, even if the small flow rate valve 24 is opened as described above, the coolant discharged from the water jacket 2 does not easily reach the vicinity of the temperature sensing portion of the large flow rate valve 23 made of a thermostat. As shown by the two-dot chain line, the coolant temperature in the vicinity of the temperature sensing portion of the large flow valve 23 only rises relatively slowly. Therefore, the opening timing of the large flow valve 23 in this comparative example is likely to be delayed as shown in FIG. 6 compared to the opening timing of the large flow valve 23 in this embodiment. Thus, in the case of the comparative example, there is a concern about the response delay of the large flow valve 23.

  Thereafter, the coolant temperature thw3 on the upstream side in the coolant flow direction of the radiator thermostat 16 in the circulation path 3 rises, and this coolant temperature thw3 is equal to or higher than the fully open temperature (engine warm-up completion temperature) X2 of the radiator thermostat 16. Then, the thermostat 16 for the radiator is fully opened. As a result, as shown by the arrows in FIG. 3, the coolant in the water jacket 2 is cooled by passing through the radiator passage 4 and the radiator 15 and then flows into the circulation passage 3. A part of the coolant circulating in the circulation path 3 is returned to the water jacket 2 through the reflux path 5. In this way, the coolant temperature thw1 of the water jacket 2 and the coolant temperature thw2 of the circulation path 3 are maintained within a predetermined temperature range.

  As described above, in this embodiment, when the coolant circulation process is required, the E / G_ECU 100 opens the small flow rate valve 24 to open the circulation path 3 from the water jacket 2 through the second bypass passage 22. A relatively small amount of cooling liquid is caused to flow in to gradually reduce the difference between the cooling liquid pressure in the upstream region and the cooling fluid pressure in the downstream region of the large flow valve 23 in the coolant flow direction. The large flow rate valve 23 made of a thermostat is automatically opened as the temperature of the circulating coolant circulates.

  As a result, sudden changes in the coolant temperature and the coolant flow rate of the water jacket 2 are suppressed. Therefore, for example, the coolant temperature thw1 on the discharge side of the water jacket 2 is monitored, and fuel injection control and ignition for the engine 1 are performed. When control is performed, the control is not disturbed. Further, since the rapid change in the coolant temperature and the coolant flow rate in the circulation path 3 is suppressed, the heating temperature can be prevented from changing rapidly during heating.

  Further, when the small flow rate valve 24 is opened, the coolant flowing from the water jacket 2 into the second bypass passage 22 flows near the temperature sensing portion of the large flow rate valve 23 made of the thermostat. Since the temperature sensing part of the large flow valve 23 composed of the thermostat can sense the temperature change of the nearby coolant as quickly as possible, the large flow valve As a result, the open / close response of 23 is improved. Therefore, it becomes possible to promote the temperature rise of the circulating coolant as quickly as possible.

  As described above, in the embodiment to which the present invention is applied, the small flow valve 24 made of an electromagnetic valve and the large flow valve 23 made of a thermostat are used as valves for blocking and allowing the coolant flow from the water jacket 2 to the circulation path 3. With this configuration, it is possible to improve the open / close response of the large flow valve 23 made of the thermostat while reducing the equipment cost of the entire engine cooling device. In this case, it is possible to eliminate the concern that a response delay of the large flow valve 23 occurs.

  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.

  For example, an exhaust heat recovery device (not shown) can be installed in the circulation path 3 shown in the above embodiment. This exhaust heat recovery device is a heat exchanger for exchanging heat between the exhaust gas discharged from the engine 1 and the coolant flowing through the circulation path 3. This exhaust heat recovery device can be installed, for example, in the downstream region 3b of the circulation path 3 upstream of the heater core 12 in the coolant flow direction (the reflux path 5 side).

  In this configuration, when the coolant is circulated only in the circulation path 3 without circulating the coolant through the water jacket 2, the temperature of the coolant in the circulation path 3 is increased by the heat recovered by the exhaust heat recovery device. As a result, the circulation path 3 can be warmed up. Therefore, for example, when the driver requests heating when the engine 1 is cold-started, heating can be performed promptly.

  The present invention includes a water jacket of an engine, a circulation path outside the engine, first and second bypass passages for allowing coolant in the water jacket to flow into the circulation path by bypassing the radiator. It can be suitably used for an engine cooling device having a large flow valve installed in the bypass passage and a small flow valve installed in the second bypass passage.

DESCRIPTION OF SYMBOLS 1 Engine 2 Water jacket 2a Water jacket discharge port 2b Water jacket inlet 3 Circulation path 3a Upstream area of the circulation path 3b Downstream area of the circulation path 4 Radiator passage 5 Recirculation path 11 Water pump 12 Heater core 13 Heater blower 15 Radiator 16 Radiator thermostat 21 First bypass passage 22 Second bypass passage 23 Large flow valve 24 Small flow valve 31 Engine water temperature sensor 32 Heater water temperature sensor 100 E / G_ECU
200 A / C_ECU

Claims (5)

A circulation path for circulating the coolant of the water jacket of the engine so as to be taken out and then returned; a radiator passage for allowing the coolant of the water jacket to flow into the circulation path after passing through the radiator; and First and second bypass passages for allowing the coolant to flow into the circulation path by bypassing the radiator, a large flow valve installed in the first bypass passage, and a small passage installed in the second bypass passage. A flow valve,
The large flow valve is a thermostat, and the coolant inflow side of the first bypass passage is connected to the radiator passage closer to the outlet of the water jacket than the radiator, and the coolant inflow side of the second bypass passage is The engine cooling device, wherein the first bypass passage is connected to a coolant inflow portion of the large flow valve. The engine cooling device according to claim 1, wherein
An engine cooling device, wherein a water pump and a heater core are installed in the circulation path. The engine cooling device according to claim 1 or 2,
A control device for controlling the opening and closing operation of the small flow valve;
The engine cooling device, wherein the control device opens the small flow valve when a coolant temperature of the water jacket is equal to or higher than a predetermined value. The engine cooling device according to claim 3, wherein
The engine cooling device, wherein the control device recognizes the coolant temperature of the water jacket by estimating a coolant temperature in a region where the coolant temperature is highest in the water jacket. The engine cooling device according to any one of claims 1 to 4,
In the radiator passage, a thermostat is installed on the downstream side of the radiator,
The thermostat is opened when the coolant temperature in the circulation path is equal to or higher than the engine warm-up completion temperature, so that the water jacket coolant flows into the circulation path through the radiator passage. Engine cooling device.

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