JP2013092131A - Engine cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend time that elapses before an engine 1 comes to be overheated when a flow rate control means 23 of a high-temperature coolant circuit 20 is in failure, in an engine cooling deice that independently includes the high-temperature coolant circuit 20 where a coolant of the engine 1 with a supercharger is taken out to the outside and returned, and a low-temperature coolant circuit 30 where the coolant is circulated which is supplied to a water-cooled intercooler 17 for cooling compressed intake from a supercharger compressor.SOLUTION: The engine cooling device includes: a failure determining means for investigating whether the flow rate control means 23 of the high-temperature coolant circuit 20 is in failure while the coolant cannot flow; and a coping means for increasing a coolant flow rate of the low-pressure coolant circuit 30 when a failure is detected by the failure determining means more than when the failure is not detected.

Description

  The present invention supplies a high-temperature coolant circulation path for taking out and returning the coolant of an engine with a supercharger to the outside, and a water-cooled intercooler for cooling compressed intake air from the compressor of the supercharger The present invention relates to an engine cooling device in which a low-temperature coolant circulation path through which coolant is circulated is provided independently.

  For example, in Patent Document 1, in a configuration in which cooling water is circulated independently between a water jacket of a cylinder block and a water jacket of a cylinder head, when the coolant temperature in the cylinder block reaches a failure determination temperature. A bimetal that permits the flow of cooling water from the water jacket of the cylinder block to the water jacket of the cylinder head, and a first that controls the inflow of cooling water to the water jacket of the cylinder block and the inflow of cooling water to the water jacket of the cylinder head. The structure provided with the 2nd thermostat valve is disclosed.

  In this patent document 1, it is possible to determine the closing failure of the first thermostat valve. Specifically, when the first thermostat valve is closed, the coolant in the cylinder block stops flowing and the temperature rises, so that the bimetal opens and the cylinder block moves from the cylinder head to the cylinder head. Cooling water flows in. Therefore, the electronic control unit determines whether or not the first thermostat valve is closed based on the change in the measurement data of the water temperature sensor installed in the flow path of the cylinder head.

  By the way, for example, Patent Document 2 discloses an engine cooling water circulation path for circulating cooling water of an engine with a supercharger and an intercooler cooling water circulation for circulating cooling water of a water-cooled intercooler for cooling intake air. The structure which provided the water pump installed in each circulation path and the water pump, and enabled it to circulate cooling water independently in each circulation path is described.

JP 2009-197664 A JP-A-6-81648

  In the case of the above-mentioned patent document 1, in order to determine the closed failure of the first thermostat valve, it is necessary to bother to provide a bimetal, which is expensive. Furthermore, because of the relationship of examining changes in the measurement data of the water temperature sensor installed in the flow path of the cylinder head, it is considered that the control logic is complicated, such as the need to monitor the measurement data one by one with the electronic control unit. .

  The above-mentioned Patent Document 2 only discloses a configuration including two circulation paths, and there is no description of detecting a closed failure of a control valve for switching between cooling water circulation and circulation stop of the engine cooling water circulation path. Of course, there is no description about what to do when the closed failure occurs.

  In view of such circumstances, the present invention provides a high-temperature coolant circulation path for taking out the coolant of an engine with a supercharger and returning it to the outside, and cooling compressed intake air from the compressor of the supercharger. In an engine cooling device provided with a low-temperature coolant circulation path through which coolant supplied to a water-cooled intercooler is circulated independently, when the flow control means of the high-temperature coolant circulation path fails, the engine overheats. The purpose is to make it possible to extend the time it takes to reach.

  The present invention supplies a high-temperature coolant circulation path for taking out and returning the coolant of an engine with a supercharger to the outside, and a water-cooled intercooler for cooling compressed intake air from the compressor of the supercharger And a low-temperature coolant circulation path through which the coolant to be circulated is provided independently, and both the coolant circulation paths are each provided with a flow rate control means for controlling the flow rate of the coolant. A failure determination means for determining whether or not the flow rate control means of the high-temperature coolant circulation path has failed in a state in which the coolant cannot flow, and the failure determination means has determined that a failure has occurred. And a coping means for increasing the coolant flow rate in the low-temperature coolant circulation path as compared with the case where there is no failure.

  In the first place, when the engine is cold started, the temperature of the coolant in the high-temperature coolant circulation path rises with the heat of the combustion chamber of the engine, and when the engine is warmed up, the coolant is circulated by circulating the coolant in the high-temperature coolant circulation path. The temperature is kept at the warm-up completion temperature. On the other hand, since the low-temperature coolant circulation path is provided for the purpose of cooling the compressed intake air from the supercharger compressor with a water-cooled intercooler, the coolant temperature in the low-temperature coolant circulation path is relatively low. There is a need to. For this reason, the coolant circulation path for cooling the engine is referred to as a “high temperature coolant circulation path”, and the coolant circulation path for cooling the intercooler is referred to as a “low temperature coolant circulation path”.

  Here, when the engine is operated, the coolant temperature in the high-temperature coolant circulation path rises with the combustion operation. At this time, the flow rate control means in the high-temperature coolant circulation path fails and the coolant When the engine no longer circulates, the engine tends to overheat over time.

  Therefore, in the present invention, when the flow rate control means of the high-temperature coolant circulation path fails, the cooling air circulation action by the intercooler is increased by increasing the flow rate of the coolant in the low-temperature coolant circulation path. I try to increase it. Thereby, since the engine is indirectly cooled, it is possible to extend the time until the engine is overheated.

  In addition, it becomes possible to detect a failure of the flow rate control means of the high-temperature coolant circulation path without adding extra components such as bimetal as shown in Patent Document 1, as well as processing relating to the failure determination and The countermeasure at the time of the failure detection is relatively simple.

  Preferably, the flow rate control means of the low-temperature coolant circulation path is an electric water pump, and the coping means has a capacity of the water pump to increase the coolant flow rate compared to the case without the failure. The configuration can be large.

  This configuration clarifies how to deal with the failure of the flow rate control means of the high-temperature coolant circulation path. It should be noted that when the capacity of the electric water pump is controlled, it is possible to adjust the circulation rate of the coolant in the low-temperature coolant circulation path.

  Preferably, the high-temperature coolant circulation path is provided with a water jacket in the block of the engine and a water jacket in the head, and a mechanical water pump driven by the engine in the middle and discharged from both the water jackets. A radiator passage for returning the water to the water jackets through the radiator, a head side control valve and a block side control valve provided in the radiator passage for individually controlling the coolant flow rates of the water jackets, and the radiator A radiator bypass passage connected to the passage so as to bypass the radiator, and a radiator thermostat provided between the radiator passage downstream of the radiator in the coolant flow direction and the downstream connection portion of the radiator bypass passage in the radiator passage And be prepared That can be configured.

  Here, the configuration of the embodiment is clarified by specifying the configuration of the high-temperature coolant circulation path. The thermostat means a temperature sensing type automatic opening / closing valve in the automotive industry.

  With such a configuration, when the engine is cold-started, the head side control valve and the block side control valve can prevent the coolant from flowing through the water jacket in the block and the water jacket in the head. By doing so, it is possible to promote the temperature rise of the engine and the coolant. Further, when the local coolant in the cylinder head is excessively heated during engine warm-up, a head-side control valve can secure a path for circulating the coolant through the water jacket in the head. This makes it possible to quickly eliminate the excessive temperature rise.

  Preferably, the head side control valve is a flow rate control means for the high-temperature coolant circulation path, and a closed failure of the head side control valve is the failure.

  Here, the flow rate control means of the high-temperature coolant circulation path is specified, and the failure mode is specified. The closed failure is a failure that does not move in the closed state.

  Preferably, the failure determination means determines whether a result obtained by subtracting a coolant temperature outside the engine from a coolant temperature in the engine after a command to open the head side control valve is greater than a predetermined value. It is possible to make a configuration in which it is determined whether or not the head side control valve has a closed failure when it is greater than or equal to the predetermined value.

  Here, the failure determination mode of the head side control valve is specified. This identification makes it clear that the failure determination can be executed by a relatively simple control logic.

  Preferably, the mechanical water pump is a flow rate control means for the high-temperature coolant circulation path, and the malfunction of the water pump is regarded as the failure.

  Here, the flow rate control means of the high-temperature coolant circulation path is specified, and the failure mode is specified.

  Preferably, the failure determination means determines whether a result obtained by subtracting a coolant temperature outside the engine from a coolant temperature in the engine after a command to open the head side control valve is greater than a predetermined value. It can be set as the structure which investigates whether it is determined and it determines with the said water pump being out of order when it is more than the said predetermined value.

  Here, the form of water pump failure determination is specified. This identification makes it clear that the failure determination can be executed by a relatively simple control logic.

  The present invention supplies a high-temperature coolant circulation path for taking out and returning the coolant of an engine with a supercharger to the outside, and a water-cooled intercooler for cooling compressed intake air from the compressor of the supercharger In an engine cooling device that is independently provided with a low-temperature coolant circulation path through which the coolant is circulated, when the flow control means of the high-temperature coolant circulation path fails, the time until the engine overheats is extended. It becomes possible to do.

FIG. 3 is a diagram schematically showing a configuration of an embodiment of the engine cooling device according to the present invention, and a coolant circulation path when all of the block-side control valve, the head-side control valve, and the radiator thermostat are closed. Is shown. It is a figure for demonstrating the circulation path | route of a cooling fluid when only a head side control valve opens in FIG. FIG. 2 is a diagram for explaining a coolant circulation path when both a block-side control valve and a head-side control valve are opened in FIG. 1. FIG. 2 is a diagram for explaining a coolant circulation path when all of a block-side control valve, a head-side control valve, and a radiator thermostat are opened in FIG. 1. FIG. 5 is a flowchart used for explaining diagnosis and coping with closing failure of the head side control valve of FIGS. 1 to 4;

  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. In this embodiment, a cooling device used for the in-line multi-cylinder engine 1 is taken as an example. Although not shown, the engine 1 is provided with a supercharger such as a known turbocharger.

  The engine 1 is provided with a high-temperature coolant circulation path 20 and a low-temperature coolant circulation path 30. The high-temperature coolant circulation path 20 and the low-temperature coolant circulation path 30 are separated from each other so that the coolant cannot be circulated. The coolant filled in the high-temperature coolant circulation path 20 and the low-temperature coolant circulation path 30 is an antifreeze such as a general ethylene glycol aqueous solution. The engine cooling device of the present invention includes a high-temperature coolant circulation path 20, a low-temperature coolant circulation path 30, and components related thereto.

  First, the low-temperature coolant circulation path 30 will be described. The low-temperature coolant circulation path 30 is a closed loop so that coolant for cooling the turbine housing 16 and the water-cooled intercooler 17 of the following turbocharger can be circulated.

  Although the turbocharger is not shown in detail, the turbine is rotated by the exhaust gas flowing into the turbine housing 16 from the exhaust passage of the engine 1, and the compressor that rotates integrally with the turbine is moved from the intake passage of the engine 1. The intake air taken into the compressor housing is compressed (supercharged), and this compressed air is taken into the engine 1. Since the density of the compressed intake air increases and the temperature rises, a water-cooled intercooler 17 is provided to cool the compressed intake air.

  The water-cooled intercooler 17 includes a heat exchanger for exchanging heat between the compressed intake air from the compressor and the coolant, and the coolant in the intercooler 17 circulates in the low-temperature coolant circulation path 30. It has come to be. Further, since the turbine housing 16 becomes hot, the low-temperature coolant circulation path 30 is inserted into the turbine housing 16 in order to cool the turbine housing 16. That is, the turbine housing 16 is cooled by heat exchange between the coolant flowing through the low-temperature coolant circulation path 30 and the turbine housing 16.

  A reserve tank 31, a radiator 32, and an electric water pump 33 are installed in the low-temperature coolant circulation path 30.

  The reserve tank 31 stores a predetermined amount of coolant and has a coolant supply port. The radiator 32 is a heat exchanger for exchanging heat between the coolant flowing through the low-temperature coolant circulation path 30 and the atmosphere.

  The electric water pump 33 causes the coolant to flow in the low-temperature coolant circulation path 30, and corresponds to “a flow rate control means for the low-temperature coolant circulation path 30”. The capacity of the water pump 33 is duty-controlled by the ECU 100 described below. In other words, the ECU 100 inputs an appropriate command signal to a driver unit (not shown) to cause the driver unit to supply a signal composed of a pulse wave with an appropriate duty ratio to the water pump 33.

  In the low-temperature coolant circulation path 30 having such a configuration, when the coolant is circulated in the closed-loop low-temperature coolant circulation path 30 by operating the electric water pump 33, the circulating coolant circulates in the turbine housing 16. The heat accumulated in the intercooler 17 is recovered, and the heat of the coolant is released to the atmosphere by the radiator 32.

  Next, the high-temperature coolant circulation path 20 will be described in detail. The high-temperature coolant circulation path 20 is a closed loop so that the coolant of the engine 1 is once taken out and then returned. The high-temperature coolant circulation path 20 includes at least an internal passage (water jackets 4 and 5) of the engine 1 and an external passage (a radiator passage 7, a radiator bypass passage 8, and an engine bypass passage 9).

  The internal passage of the engine 1 includes a water jacket 4 provided in the cylinder block 2 of the engine 1 and a water jacket 5 provided in the cylinder head 3 of the engine 1. The external passage of the engine 1 includes at least a radiator passage 7 and a radiator bypass passage 8.

  The coolant inflow portion 4 a of the water jacket 4 in the block is provided below one end surface (for example, the front end surface) in the cylinder arrangement direction in the cylinder block 2. The coolant inflow portion 5a of the water jacket 5 in the head is provided on one end surface (for example, the front end surface) of the cylinder head 3 in the cylinder arrangement direction.

  The coolant discharge portion of the water jacket 4 in the block and the coolant discharge portion of the water jacket 5 in the head are merged at their ends, and this merge end portion serves as a common discharge portion 6 in the cylinder head 3. It is provided on the other end surface (for example, the rear end surface) in the cylinder arrangement direction.

  The radiator passage 7 circulates the coolant discharged from at least one of the block water jacket 4 and the head water jacket 5 to at least one of the block water jacket 4 and the head water jacket 5. It is.

  One end of the radiator passage 7 (upstream end side in the coolant flow direction) is a single coolant inflow portion 7a, but the other end side (downstream end side in the coolant flow direction) of the radiator passage 7 is bifurcated. Branched. Of the two branched branch parts, one is a block-side coolant reflux part 7b and the other is a head-side coolant reflux part 7c.

  One coolant inflow portion 7 a of the radiator passage 7 is connected to the common discharge portion 6 of both the water jackets 4 and 5. Further, the block side coolant recirculation part 7b of the radiator passage 7 is connected to the coolant inflow part 4a of the water jacket 4 in the block, and the head side coolant return part 7c of the radiator passage 7 is connected to the water jacket 5 in the head. Is connected to the coolant inflow portion 5a.

  The radiator passage 7 is provided with a mechanical water pump 11 and a radiator 12. The water pump 11 is provided upstream of the bifurcated branch portion of the radiator passage 7 in the coolant flow direction. Although not shown, the water pump 11 is driven by transmitting the rotational power of the crankshaft of the engine 1 via a power transmission device (including pulleys, belts, etc.). The radiator 12 exchanges heat between the coolant flowing through the high-temperature coolant circulation path 20 and the atmosphere, and is mainly a heat exchanger for cooling.

  The radiator bypass path 8 is connected to the radiator passage 7 so as to bypass the radiator 12. A heater core 13 is provided in the middle of the radiator bypass 8. The heater core 13 is a heat exchanger for exchanging heat between the coolant flowing through the radiator bypass 8 and the vehicle compartment. The heat released from the heater core 13 is supplied to the vehicle interior by the heater blower 14 to heat the vehicle interior. The operation of the heater blower 14 is controlled by an electronic control unit (hereinafter simply referred to as ECU) 100 described below.

  A radiator thermostat 21 is provided in the radiator passage 7 between a position downstream of the radiator 12 in the coolant flow direction and a downstream connection portion of the radiator bypass 8.

  Since this radiator thermostat 21 has a known configuration, a detailed illustration and description thereof are omitted, but generally includes a valve body and a thermoactuator. The thermoactuator includes a temperature sensing part filled with thermowax, and a plunger provided in the temperature sensing part to displace the valve body in the valve opening direction or the valve closing direction.

  Here, the operation of the radiator thermostat 21 will be described. In the radiator passage 7, when the coolant temperature thw4 in the downstream connection portion with the radiator bypass passage 8 is lower than the overheat prevention temperature Z, the thermowax is solidified and contracted and the wax pressure is lowered, so that the plunger The valve element is displaced to the fully closed position by being drawn into the warm section. The overheat prevention temperature Z is set to an arbitrary value higher than the warm-up completion temperature (for example, 85 ° C. to 90 ° C., preferably 88 ° C.). When the coolant temperature thw4 is equal to or higher than the overheat prevention temperature Z, the thermowax is melted and expanded to increase the wax pressure, so that the plunger jumps out of the temperature sensing portion and opens the valve body. become. As a result, the coolant flows through both the radiator passage 7 and the radiator bypass passage 8.

  In this embodiment, a block-side control valve 22 is provided in the block-side coolant return part 7 b of the radiator passage 7, and a head-side control valve 23 is provided in the head-side coolant return part 7 c of the radiator passage 7. .

  Furthermore, in this embodiment, an engine bypass passage 9 for bypassing the internal passages (4, 5) is connected to the radiator passage 7. The engine bypass path 9 is upstream of the block side control valve 22 in the coolant flow direction in the block side coolant recirculation part 7b, and is further downstream in the coolant flow direction in the radiator path 7 than the radiator bypass path 8 and the heater core 13. It is connected to the. The engine bypass path 9 is provided with an oil cooler 15 for cooling the oil of the engine 1.

  The block side control valve 22 is a thermostat, and allows or blocks the coolant flow in the block side coolant recirculation unit 7b. In this embodiment, the head-side control valve 23 is an electromagnetic valve that allows or blocks the coolant flow in the head-side coolant recirculation unit 7c. It corresponds to “means”. The block side control valve 22 and the head side control valve 23 can also restrict the coolant flow.

  Since the thermostat as the block-side control valve 22 has basically the same configuration as the above-described radiator thermostat 21, a detailed description and explanation are omitted, but 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 in the valve opening direction or the valve closing direction.

  Here, the operation of the thermostat as the block-side control valve 22 will be described. When the coolant temperature thw1 on the upstream side in the coolant flow direction with respect to the block side control valve 22 in the block side coolant recirculation unit 7b is lower than a predetermined valve opening temperature X, the thermowax solidifies and shrinks and the wax pressure decreases. Therefore, the valve body is automatically closed, and the inflow of the coolant from the radiator passage 7 to the water jacket 4 in the block is stopped. The valve opening temperature X is set to an arbitrary value that is higher than the warm-up completion temperature and lower than the overheat prevention temperature Z. When the coolant temperature thw1 becomes equal to or higher than the valve opening temperature X, the thermowax is melted and expanded to increase the wax pressure, so that the valve body is automatically opened and the water jacket 4 in the block is opened from the radiator passage 7. Let the coolant flow into the tank.

  Next, the electromagnetic valve as the head side control valve 23 is a normally closed type. The opening / closing operation of the head side control valve 23 is controlled by the ECU 100. For example, when the ECU 100 energizes a coil (not shown) of the head-side control valve 23, the valve body is opened, and when energization of the coil is stopped, the valve body is closed.

  The ECU 100 is, for example, an existing engine control computer that is essential for various operation controls of the engine 1. In this embodiment, the existing ECU 100 is provided with a function for controlling the head-side control valve 23 of the high-temperature coolant circulation path 20 and the electric water pump 33 of the low-temperature coolant circulation path 30 described above. Yes.

  Although not shown in detail, the 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 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 ECU 100 can adjust the temperature of the engine 1 by controlling the operation of the head-side control valve 23 and the like based on the detection output input from the first temperature sensor 41, for example. The first temperature sensor 41 is provided in the vicinity of the common discharge part 6 of the water jackets 4 and 5 at the coolant inflow part 7a of the radiator passage 7, and the coolant temperature thw2 (engine coolant temperature in the engine) at the installation location. (Also called).

  Specifically, the basic operation by the engine cooling device of this embodiment will be described.

  For example, when the engine 1 is cold-started, that is, when the detection output of the first temperature sensor 41 (engine coolant temperature thw2) is less than a predetermined cold-start determination reference value Y when the engine 1 is started, the ECU 100 The head side control valve 23 composed of an electromagnetic valve is instructed to be closed. The cold start determination reference value Y is set to an arbitrary value lower than the warm-up completion temperature.

  When both the radiator thermostat 21 and the block-side control valve 22 including the thermostat are closed by such an instruction, the coolant does not flow in the water jackets 4 and 5 as indicated by the solid arrows in FIG. Stops without distributing. As a result, the temperature of the coolant in the engine 1 and the water jackets 4 and 5 is promoted by heat generated from the cylinder head 3, particularly from the combustion chamber. However, since the mechanical water pump 11 is driven by the engine 1 in this state, the coolant circulates in a shortcut path formed by the upstream and downstream sides of the water pump 11 and the engine bypass path 9 in the radiator passage 7. It becomes like this.

  Thus, after the coolant in the engine 1 and the water jackets 4 and 5 rises in temperature, the engine coolant temperature thw2 becomes equal to or higher than the cold start determination reference value Y, and then the water in the head. When the ECU 100 detects that the temperature of the coolant has excessively increased (boiling) locally in the jacket 5 (near the cylinder head combustion chamber), the ECU 100 instructs the head-side control valve 23 to open.

  As an example of the method for detecting the excessive temperature rise, cooling in the maximum temperature reaching region in the cylinder head 3 in the water jacket 5 in the head is performed every predetermined period (several milliseconds to several tens of milliseconds) from the start of the engine 1. This can be done by estimating the maximum liquid temperature. As an example of this estimation method, a process for recognizing the initial value of the engine coolant temperature thw2 based on the detection output from the first temperature sensor 41 at the start of the engine 1, and the engine after the engine 1 is started By calculating the generated heat quantity of 1 and calculating the rise value of the maximum temperature reaching area in the cylinder head due to this generated heat quantity, and adding this rise value to the previous estimated value (the initial value is the initial value) A process for estimating the current coolant temperature in the maximum temperature reaching region in the cylinder head, and a process for determining that the boiling occurs when the estimated value exceeds a predetermined temperature (for example, 96 ° C.). I do.

  When the head side control valve 23 is opened as described above, the coolant in the head water jacket 5 is discharged from the common discharge portion 6 to the radiator passage 7 as shown by the solid line arrow in FIG. Instead of flowing into the radiator 12, it flows through the radiator bypass path 8, flows into the head side coolant recirculation unit 7 c, and further flows into the head inner water jacket 5 through the head side control valve 23.

  In this way, when the coolant repeatedly flows through the water jacket 5 in the head, the coolant absorbs heat of the cylinder head 3 particularly in the vicinity of the combustion chamber. As a result, the coolant is prevented from excessively rising (boiling) locally in the water jacket 5 in the head, while the coolant in the cylinder block 2 and the water jacket 4 in the block is gradually heated. Become. As a result, the temperature rise is promoted while keeping the temperature difference between the cylinder block 2 and the cylinder head 3 as small as possible.

  By the way, in the rising process until the coolant temperature thw1 on the upstream side in the coolant flow direction of the block side control valve 22 reaches the valve opening temperature X of the block side control valve 22 in the block side coolant circulating portion 7b of the radiator passage 7. Although the block side control valve 22 remains closed, the block side control valve 22 is automatically opened when the coolant temperature thw1 becomes equal to or higher than the valve opening temperature X. When the block-side control valve 22 is opened, the coolant in the head water jacket 5 is discharged from the common discharge portion 6 to the radiator passage 7 and flows into the radiator 12 as shown by the solid arrows in FIG. Without passing through the radiator bypass path 8, it flows into the head-side coolant recirculation unit 7 c, and further flows into the head water jacket 5 through the head-side control valve 23, while cooling through the radiator bypass path 8. The liquid is allowed to flow into the water jacket 4 in the block via the block-side coolant recirculation part 7b and the block-side control valve 22. As a result, a sufficient amount of coolant is circulated between the radiator bypass path 8 of the radiator passage 7 and the water jacket 4 in the block and the water jacket 5 in the head.

  Thereafter, when the coolant temperature thw4 at the downstream connection portion with the radiator bypass path 8 in the radiator passage 7 becomes equal to or higher than the overheat prevention temperature Z, the radiator thermostat 21 is automatically opened. As indicated by solid arrows, the coolant discharged from the common discharge portion 6 of the block water jacket 4 and the head water jacket 5 to the radiator passage 7 flows not only to the radiator bypass path 8 but also to the radiator 12. . The coolant that has passed through the radiator bypass 8 and the radiator 12 is returned to the water jackets 4 and 5. Thus, since the coolant discharged from the water jackets 4 and 5 is circulated so as to be returned to the water jackets 4 and 5 after being cooled by the radiator 12, the circulating coolant and the temperature of the engine 1 are As a result of being adjusted within a certain range, overheating of the engine 1 is avoided and kept at an appropriate temperature.

  Further, in this embodiment, it is possible to determine whether or not a closing failure of the electromagnetic valve as the head-side control valve 23 has occurred, and to take appropriate measures when the closing failure occurs. Hereinafter, a detailed description will be given with reference to FIGS. 5 and 6.

  In order to determine the presence or absence of the closed failure, a second temperature sensor 42 is provided in the engine bypass passage 9 on the upstream side of the oil cooler 15 in the coolant flow direction. The coolant temperature thw3 (also referred to as engine coolant temperature outside the engine) at the installation location is detected.

  When the ECU 100 outputs a signal for opening the head-side control valve 23 (instruction for opening operation), the difference between the engine coolant temperature thw2 and the engine coolant temperature thw3 is a predetermined value α. When this is the case, the ECU 100 determines that the head side control valve 23 has a closed failure.

  Specifically, with reference to the flowchart shown in FIG. 5, processing relating to the presence / absence determination of the head side control valve 23 will be described.

  This flowchart shows processing by the ECU 100, and is started every predetermined cycle (several milliseconds to several tens of milliseconds) after the engine 1 is started. When this flowchart is started, first, in step S1, it is determined whether or not a signal for opening the head-side control valve 23 is output (instruction for opening operation).

  If the valve opening signal is not output, a negative determination is made in step S1, and the flowchart is terminated. However, when the valve opening signal is output, an affirmative determination is made in step S1, and the process proceeds to the subsequent step S2.

  In step S2, the process waits for a predetermined time to elapse. When the predetermined time has elapsed (Yes determination in step S2), in subsequent step S3, it is determined whether or not the difference between the engine coolant temperature thw2 and the engine coolant temperature thw3 is equal to or greater than a predetermined value α. The predetermined time refers to the temperature of the coolant in the water jacket 5 in the head (detection of the first temperature sensor 41), particularly if the head side control valve 23 is closed after the valve opening signal is output. It is set based on the time required for the coolant temperature thw2) recognized based on the output to rise excessively. This set time can be appropriately determined by an appropriate experiment or simulation.

  Here, even if the head side control valve 23 is instructed to open as described above, if the head side control valve 23 is closed, the coolant in the head water jacket 5 stops. As a result, the coolant temperature (thw2) of the water jacket 5 in the head excessively increases, while the coolant temperature (thw3) of the external passages (7-9) hardly changes. That is, the difference between the engine coolant temperature thw2 and the engine coolant temperature thw3 gradually increases. However, when the head side control valve 23 is normally opened in response to the valve opening instruction, the coolant flows between the head water jacket 5 and the external passages (7-9). The difference between the engine coolant temperature thw2 and the engine coolant temperature thw3 is reduced.

  Based on the knowledge of such a phenomenon, when thw2−thw3 ≧ α, an affirmative determination is made in step S3, and in the subsequent step S4, it is determined that the head-side control valve 23 has a closed failure. On the other hand, when thw2−thw3 <α, a negative determination is made in step S3, and in the subsequent step S5, it is determined that the head side control valve 23 is normal, that is, a closed failure has not occurred.

  If it is determined in step S4 that the head-side control valve 23 has a closed failure, the electric water pump 33 is operated with the maximum capacity in step S6. As a result, the coolant flow rate in the low-temperature coolant circulation path 30 is maximized, so that the heat exchange cycle in which the heat of the turbine housing 16 and the intercooler 17 is recovered by the coolant and released to the atmosphere by the radiator 32 is short. It will be repeated.

  As the turbine housing 16 is cooled in this manner, the engine 1 to which it is attached is indirectly cooled. At the same time, the intercooler 17 is cooled, whereby the compressed air supplied from the supercharger compressor to the engine 1 is cooled, so that the engine 1 is indirectly cooled. For this reason, even when the head side control valve 23 fails to close and the coolant does not flow through the water jacket 5 in the head of the engine 1, the time until the engine 1 reaches overheating is extended. It becomes possible.

  By the way, the function (steps S1 to S5) executed by the ECU 100 corresponds to the failure determination means described in the claims, and the function (step S6) executed by the ECU 100 is the countermeasure means described in the claims. It corresponds.

  As described above, in the embodiment to which the present invention is applied, the coolant is circulated independently between the block water jacket 4 and the head water jacket 5 of the engine 1 by the block side control valve 22 and the head side control valve 23. In the possible configuration, the presence or absence of a closed failure of the head side control valve 23 is examined, and when it is determined that the closed failure has occurred, the coolant flow rate in the low-temperature coolant circulation path 30 is maximized. Thus, the engine 1 is indirectly cooled.

  This makes it possible to extend the time until the engine 1 reaches overheating even when the head side control valve 23 closes and the coolant does not flow through the water jacket 5 in the head of the engine 1. Therefore, it is possible to reduce the burden on the vehicle user, for example, it is possible to receive repairs before the engine 1 is seriously damaged.

  In addition, it becomes possible to detect a closing failure of the head-side control valve 23 without adding an extra component such as a bimetal as shown in Patent Document 1, as well as processing related to the determination of the closing failure and the closing failure. Since the control logic of the ECU 100 for executing the countermeasure at the time of detection is relatively simple, it is possible to reduce the increase in the equipment cost of the engine cooling device.

  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) In the above embodiment, an example is given in which the water pump 11 installed in the high-temperature coolant circulation path 20 is a mechanical type, but the present invention is not limited to this, and for example, an electric type is used. It is also possible.

  (2) In the above embodiment, an example in which the head-side control valve 23 installed in the high-temperature coolant circulation path 20 is an electromagnetic valve is given, but the present invention is not limited to this. The head side control valve 23 may be any type of control valve that operates upon receiving an operation instruction from the ECU 100, for example, and may be an electric valve that is operated by a motor or the like.

  (3) In the above embodiment, an example in which the block-side control valve 22 installed in the high-temperature coolant circulation path 20 is a thermostat is given, but the present invention is not limited to this. The block-side control valve 22 can be a control valve that operates in response to an operation instruction from the ECU 100, for example, an electromagnetic valve or an electric valve that is operated by a motor or the like.

  The present invention supplies a high-temperature coolant circulation path for taking out and returning the coolant of an engine with a supercharger to the outside, and a water-cooled intercooler for cooling compressed intake air from the compressor of the supercharger It can be suitably used for an engine cooling device provided with a low-temperature coolant circulation path through which the coolant to be circulated is provided independently.

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder block 3 Cylinder head 4 Water jacket in block 4a Coolant inflow part of water jacket in block 5 Water jacket in head 5a Coolant inflow part of water jacket in head 6 Common discharge part of both water jackets 7 Radiator passage 7a Coolant inflow portion of radiator passage 7b Block side coolant return portion of radiator passage 7c Head side coolant return portion of radiator passage 8 Radiator bypass passage 11 Water pump 12 Radiator 16 Turbocharger turbine housing 17 Water-cooled intercooler 20 High-temperature coolant circulation path 21 Thermostat for radiator 22 Block-side control valve 23 Head-side control valve (equivalent to flow control means for high-temperature coolant circulation path)
30 Low-temperature coolant circulation path 31 Reserve tank 32 Radiator 33 Water pump (equivalent to the flow control means of the low-temperature coolant circulation path)
41 1st temperature sensor 42 2nd temperature sensor 100 ECU

Claims (7)

A coolant supplied to a high-temperature coolant circulation path for taking out and returning the coolant of the engine with the supercharger to the outside and a water-cooled intercooler for cooling the compressed intake air from the compressor of the supercharger An engine cooling device provided independently with a circulating low-temperature coolant circulation path,
Both the coolant circulation paths are each provided with a flow rate control means for controlling the flow rate of the coolant.
Failure determination means for determining whether or not the flow rate control means of the high-temperature coolant circulation path has failed in a state in which the coolant cannot flow; and
An engine cooling apparatus comprising: a coping means for increasing the coolant flow rate of the low-temperature coolant circulation path as compared with a case where there is no failure when it is determined that the failure is determined by the failure determination means. The engine cooling device according to claim 1, wherein
The flow rate control means of the low-temperature coolant circulation path is an electric water pump,
The engine cooling apparatus according to claim 1, wherein the coping means increases the capacity of the water pump in order to increase the coolant flow rate as compared with the case without the failure. The engine cooling device according to claim 1 or 2,
The high-temperature coolant circulation path includes a water jacket in the engine block and a water jacket in the head,
A radiator water passage provided with a mechanical water pump driven by an engine and returning the coolant discharged from both water jackets to both water jackets through a radiator;
A head-side control valve and a block-side control valve provided in the radiator passage for individually controlling the coolant flow rates of the water jackets;
A radiator bypass path connected to the radiator path to bypass the radiator;
An engine cooling device comprising: a radiator thermostat provided between a downstream side of the radiator passage in a coolant flow direction and a downstream side connecting portion of the radiator bypass passage in the radiator passage. The engine cooling device according to claim 3, wherein
2. The engine cooling apparatus according to claim 1, wherein the head side control valve serves as a flow rate control means for the high-temperature coolant circulation path, and a closed failure of the head side control valve is the failure. The engine cooling device according to claim 4, wherein
The failure determination means determines whether or not the result of subtracting the coolant temperature outside the engine from the coolant temperature inside the engine is equal to or greater than a predetermined value after the opening side operation of the head side control valve is instructed. An engine cooling apparatus characterized by examining and determining that the head side control valve has a closed failure when the value is equal to or greater than the predetermined value. The engine cooling device according to claim 3, wherein
The engine-type water pump is characterized in that the mechanical water pump serves as a flow rate control means for the high-temperature coolant circulation path, and the malfunction of the water pump is regarded as the failure. The engine cooling device according to claim 6, wherein
The failure determination means determines whether or not the result of subtracting the coolant temperature outside the engine from the coolant temperature inside the engine is equal to or greater than a predetermined value after the opening side operation of the head side control valve is instructed. An engine cooling apparatus characterized by examining and determining that the water pump is in failure when the predetermined value or more is exceeded.

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