JP7230664B2 - engine cooling system - Google Patents

Description

The present invention relates to a cooling device applied to an engine.

2. Description of the Related Art An engine provided in a vehicle or the like is configured such that cooling water is pressure-fed to an engine body and accessories by a water pump rotationally driven by the engine. Also, a flow control valve capable of opening and closing the flow control valve is provided in the path through which the cooling water flows, and the flow rate of the cooling water is changed by opening and closing the flow control valve.

For example, in Patent Document 1, a flow control valve that opens and closes the passage is provided in the middle of the passage that connects the engine body and the radiator and the cooling water flows inside, and the opening degree of this flow control valve is changed. Thus, an engine is disclosed in which the flow rate of cooling water flowing through the passage and, in turn, the temperature of the engine body are adjusted. In this engine, it is determined whether or not the flow control valve is out of order, and if the flow control valve is out of order, the engine output is limited.

JP 2018-168753 A

In an engine provided with a flow control valve as described above, when the flow control valve fails, an appropriate amount of cooling water is not supplied to the engine body, which may cause the temperature of the engine body to become excessively high. On the other hand, according to the engine of Patent Document 1, the engine output is reduced due to the failure of the flow control valve, so it is considered possible to prevent the temperature of the engine body from becoming excessively high. However, in this engine, excessive temperature rise of the engine body is avoided only by limiting the engine output, so the engine output must be greatly reduced, resulting in a significant deterioration in engine performance.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to prevent the temperature of an engine body from becoming excessively high while suppressing a decrease in engine output.

In order to solve the above problems, the present invention provides an engine cooling device, comprising: a cooling water path for circulating cooling water through an engine body; a flow control valve capable of opening and closing the cooling water path; a control means for controlling a flow control valve, wherein the flow control valve is configured to open and close when supplied with electric power and to be fully opened when the supply of electric power is stopped; It is determined whether or not the flow control valve is out of order, and when it is determined that the flow control valve is out of order, the flow control valve is fully opened continuously for at least a predetermined period of time. power supply is stopped .

According to the present invention, when it is determined that the flow control valve is out of order, the flow control valve is controlled to be fully opened. Therefore, even when the flow control valve fails, the flow rate of cooling water passing through the flow control valve and through the engine body can be increased in some cases, and excessive temperature rise of the engine body can be suppressed. By controlling the flow rate control valve to suppress the excessive temperature rise of the engine body, it is possible to reduce the chances of restricting the engine output in order to prevent this excessive temperature increase, thereby ensuring the engine output. be possible.

Further, when it is determined that the flow control valve has failed due to foreign matter adhering to the periphery of the flow control valve, the foreign matter can be removed by increasing the flow rate passing through the flow control valve. Therefore, the flow control valve can be returned to normal without lowering the engine output, and the engine performance can be improved.

Further, when it is determined that the flow rate control valve is configured to open and close upon receipt of power and is fully opened when the power supply is stopped, and the flow rate control valve is determined to be out of order, It is configured such that the power supply to the flow control valve is stopped. Therefore, it is possible to easily keep the flow control valve open.

In the above configuration, preferably, the control means limits the output of the engine when it is determined that the flow control valve is out of order (claim 2 ).

According to this configuration, it is possible to more reliably prevent the temperature of the engine body from becoming excessively high. Here, as described above, in the present invention, the temperature rise of the engine body is suppressed by increasing the flow rate of the cooling water passing through the engine body. The deterioration of engine performance can be suppressed by reducing the limit amount.

In the above configuration, preferably, a radiator for cooling cooling water and a path for circulating the cooling water through the engine body, wherein the cooling water is diverted from the cooling water path and routed through the radiator for radiator side cooling A valve body disposed in the middle of the water path and the radiator-side cooling water path, the valve opening when the temperature of the cooling water passing through the valve body is equal to or higher than a predetermined valve opening temperature. A thermostat including a valve body that closes when the temperature is lower than the valve opening temperature and a valve opening temperature changing unit capable of changing the valve opening temperature, wherein the control means controls the flow rate control valve to malfunction. When it is determined that the valve opening temperature of the thermostat is lowered, the valve opening temperature changing unit is controlled (claim 3 ).

In this configuration, when it is determined that the flow control valve is out of order, the valve opening temperature of the thermostat is reduced and the valve main body of the thermostat is opened when the temperature of the cooling water is low. In other words, the cooling water passes through the second cooling water path in which the thermostat is arranged, increasing the opportunity, ie, the time, for the cooling water to be cooled by the radiator. Therefore, the temperature of the cooling water can be lowered to reliably cool the engine body, and the temperature of the engine body can be more reliably prevented from becoming excessively high.

In the above configuration, preferably, a pressure sensor is provided in the middle of the cooling water path and detects the pressure of the cooling water passing through the cooling water path, and the control means detects the pressure of the cooling water when the flow control valve is opened and closed. It is determined whether or not the flow control valve is out of order based on the detected value of the pressure sensor (claim 4 ).

According to this configuration, whether or not the flow control valve is out of order is determined based on pressure changes that sensitively change with respect to changes in the flow rate of the cooling water. can be determined early.

In the above configuration, preferably, the control means opens and closes the flow control valve so that the wall temperature of the combustion chamber formed in the engine body reaches a preset target temperature (claim 5 ).

According to this configuration, the wall temperature of the combustion chamber can be controlled to an appropriate temperature by opening and closing the flow control valve.

As described above, according to the engine cooling device of the present invention, it is possible to prevent the temperature of the engine body from becoming excessively high while suppressing the decrease in the engine output.

1 is a system diagram schematically showing the overall configuration of an engine to which the present invention is applied; FIG. 1 is a circuit diagram schematically showing the overall configuration of an engine cooling device; FIG. FIG. 3 is a schematic cross-sectional view showing the essential parts of the engine body; It is a schematic sectional drawing of a flow control valve. FIG. 4 is a diagram showing changes in the degree of opening of a flow control valve and accompanying changes in the pressure of cooling water; 3 is a block diagram showing a control system of the engine; FIG. 4 is a flow chart showing a procedure for determining a failure of a flow control valve; 4 is a flow chart showing a control procedure when a flow control valve fails. 4 is a flow chart showing a procedure of failure control. It is a schematic cross-sectional view of the flow control valve when foreign matter is attached.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(1) Entire Configuration of Engine FIG. 1 is a diagram showing a preferred embodiment of a vehicle engine (hereinafter simply referred to as engine) to which the control device of the present invention is applied. The engine shown in FIG. 1 is a four-cycle gasoline direct-injection engine mounted on a vehicle as a power source for running. It has an exhaust passage 40 through which exhaust gas discharged from the engine body 1 flows, and an external EGR device 50 that recirculates part of the exhaust gas flowing through the exhaust passage 40 to the intake passage 30 .

The engine body 1 includes a cylinder block 3 in which a cylinder 2 is formed, a cylinder head 4 attached to the upper surface of the cylinder block 3 so as to block the cylinder 2 from above, and a reciprocatingly slidable insertion into the cylinder 2. and a piston 5 that is The engine body 1 is typically of a multi-cylinder type having a plurality of (for example, four) cylinders 2, but for the sake of simplification, only one cylinder 2 will be described here.

A combustion chamber 6 is defined above the piston 5, and fuel containing gasoline as a main component is supplied to the combustion chamber 6 by injection from an injector 15, which will be described later. The supplied fuel burns while being mixed with air in the combustion chamber 6, and the piston 5 reciprocates vertically by receiving the expansion force due to the combustion.

A crankshaft 7 that is an output shaft of the engine body 1 is provided below the piston 5 . The crankshaft 7 is connected to the piston 5 via a connecting rod 8 and is driven to rotate about the central axis in accordance with the reciprocating motion (vertical motion) of the piston 5 .

A crank angle sensor SN1 is assembled to the cylinder block 3 . Crank angle sensor SN1 detects the rotation angle (crank angle) of crankshaft 7 and the rotation speed of crankshaft 7 (engine rotation speed).

The cylinder head 4 has an intake port 9 for introducing air supplied from an intake passage 30 into the combustion chamber 6, and an exhaust port 10 for introducing exhaust gas generated in the combustion chamber 6 to an exhaust passage 40. , an intake valve 11 for opening and closing the opening of the intake port 9 on the combustion chamber 6 side, and an exhaust valve 12 for opening and closing the opening of the exhaust port 10 on the combustion chamber 6 side. The intake valve 11 and the exhaust valve 12 are driven to open and close in conjunction with the rotation of the crankshaft 7 by a valve mechanism including a pair of camshafts arranged in the cylinder head 4 .

The cylinder head 4 has an injector 15 for injecting fuel (gasoline) into the combustion chamber 6 and a spark plug 16 for igniting a mixture of the fuel and intake air injected from the injector 15 into the combustion chamber 6. is provided.

The intake passage 30 is connected to one side surface of the cylinder head 4 so as to communicate with the intake port 9 . The intake passage 30 includes, in order from the upstream side thereof, an air cleaner 31 that removes foreign matter from the intake air, a throttle valve 32 that can be opened and closed to adjust the flow rate of the intake air, a supercharger 33 that compresses and delivers the intake air, and a supercharger. An intercooler 35 for cooling the intake air compressed by the feeder 33 and a surge tank 36 are provided. An airflow sensor SN2 for detecting the flow rate of intake air is provided in the intake passage 30 between the air cleaner 31 and the throttle valve 32 .

The supercharger 33 is a mechanical supercharger mechanically linked to the engine body 1 via an electromagnetic clutch 34 . As the supercharger 33, any known supercharger such as Lysholm type, Roots type, or centrifugal type can be used.

A bypass passage 38 for bypassing the supercharger 33 is provided in the intake passage 30 . The bypass passage 38 connects the surge tank 36 and an EGR passage 51 (to be described later) to each other. A bypass valve 39 that can be opened and closed is provided in the bypass passage 38 .

The exhaust passage 40 is connected to the other side surface of the cylinder head 4 so as to communicate with the exhaust port 10 . A catalytic converter 41 is provided in the exhaust passage 40 . The catalytic converter 41 includes a three-way catalyst 41a for purifying harmful components (HC, CO, NOx) contained in the exhaust gas flowing through the exhaust passage 40, and particulate matter (PM) contained in the exhaust gas. A GPF (gasoline particulate filter) 41b for collecting is incorporated.

The external EGR device 50 has an EGR passage 51 that connects the exhaust passage 40 and the intake passage 30 , an EGR valve 53 that opens and closes the EGR passage 51 , and an EGR cooler 52 provided in the EGR passage 51 . The EGR passage 51 connects a portion of the exhaust passage 40 downstream of the catalytic converter 41 and a portion of the intake passage 30 between the throttle valve 32 and the supercharger 33 . The EGR cooler 52 cools the exhaust gas recirculated from the exhaust passage 40 to the intake passage 30 through the EGR passage 51 by heat exchange.

The geometric compression ratio of the cylinder 2, that is, the ratio of the volume of the combustion chamber 6 when the piston 5 is at the top dead center to the volume of the combustion chamber 6 when the piston 5 is at the bottom dead center, is 13 or more and 30 or less. , preferably set to a high compression ratio of 14 or more and 18 or less.

In the present embodiment, SPCCI combustion, in which part of the air-fuel mixture is subjected to compression ignition, is performed in a low-speed region where the engine speed is equal to or lower than a predetermined speed. Thus, the geometric compression ratio of cylinder 2 is set to a relatively high value as described above.

SPCCI combustion is partial compression ignition combustion in which SI combustion and CI combustion are combined. SI combustion is a combustion mode in which a spark generated by the spark plug 16 ignites an air-fuel mixture, and flame propagation that spreads the combustion area from the ignition point to the surroundings forces the air-fuel mixture to burn. CI combustion is a combustion mode in which an air-fuel mixture is combusted by self-ignition under an environment of sufficiently high temperature and high pressure due to compression of the piston 5 or the like. SPCCI combustion, which is a combination of these SI combustion and CI combustion, involves SI combustion of part of the air-fuel mixture in the combustion chamber 6 by spark ignition performed in an environment just before the air-fuel mixture self-ignites. This is a combustion mode in which another air-fuel mixture in the combustion chamber 6 is later CI-burned by self-ignition (due to further increase in temperature and pressure accompanying SI combustion). That is, in the low speed region, fuel and air are mixed in advance, a part of this air-fuel mixture is forcibly burned by ignition from the ignition plug 16, and the remaining air-fuel mixture is compressed by the thermal energy of this combustion. Ignite. “SPCCI” is an abbreviation for “Spark Controlled Compression Ignition”. On the other hand, in the present embodiment, general SI combustion is performed in a high speed region where the engine speed is higher than in the low speed region.

(2) Overall Configuration of Cooling Device FIG. 2 is a circuit diagram showing the overall configuration of the cooling device 60 for the engine. As shown in the figure, the cooling device 60 includes a water pump (W/P) 61, a radiator (RAD) 71, and a plurality of cooling water paths 62 to 66 (main cooling water path 62) for circulating cooling water. , an EGR cooling water path 63, an ATF cooling water path 64, a communication path 65, and a valve path 66).

The water pump 61 is a pump for discharging cooling water and is attached to one side surface of the cylinder block 3 . The water pump 61 is rotationally driven by the engine body 1 . Specifically, the water pump 61 is connected to the crankshaft 7 via a belt, and is rotationally driven by the crankshaft 7 to discharge cooling water.

The radiator 71 is a heat exchanger for cooling cooling water, and when the cooling water passes through the radiator 71, it is cooled by the running wind of the vehicle or the like.

(main cooling water path)
As indicated by solid arrows in FIG. 2 , the main cooling water path 62 passes the cooling water discharged from the water pump 61 through a block-side water jacket 62 a formed in the cylinder block 3 and a combustion chamber formed in the cylinder head 4 . This is a route for circulation back to the water pump 61 via the side water jacket 62b and the radiator 71. FIG. This main cooling water path 62 corresponds to a "radiator side cooling water path" in the claims.

As shown in FIG. 3, the combustion chamber side water jacket 62b is a water jacket formed in the vicinity of the combustion chamber 6 of the cylinder head 4 and around the valve seat portions of the intake port 9 and the exhaust port 10. be.

A position between the radiator 71 and the water pump 61 in the main cooling water path 62, more specifically, downstream of the radiator 71 and upstream of the water pump 61 with respect to the flow direction of the cooling water indicated by the solid-line arrow in FIG. A first thermostat valve 72 is provided at a position on the side.

The first thermostat valve 72 is a valve body 72a (hereinafter referred to as a TS valve body 72a) that opens and closes the main cooling water path 62, and the temperature of the cooling water passing through the TS valve body 72a exceeds a predetermined valve opening temperature. A TS valve main body 72a is provided which opens (is fully opened) at times and closes (is fully closed) when the temperature of the cooling water is lower than the valve opening temperature. The first thermostat valve 72 is a variable thermostat valve capable of changing the valve opening temperature, and includes a thermostat heater 72b for changing the valve opening temperature. The thermostat heater 72b generates heat when energized. The greater the amount of electricity supplied to the thermostat heater 72b, the lower the valve opening temperature. That is, when the amount of power supplied to the thermostat heater 72b is large and the temperature of the thermostat heater 72b is high, the temperature of the cooling water is lower than when the amount of power supplied to the thermostat heater 72b is small and the temperature of the thermostat heater 72b is low. The TS valve main body 72a is opened at the timing. The amount of power supplied to the thermostat heater 72b is controlled by the PCM 100, which will be described later. The first thermostat valve 72 corresponds to the "thermostat valve" in the claims. The TS valve main body 72a corresponds to the "valve main body of the thermostat valve" in the claims, and the thermostat heater 72b corresponds to the "valve opening temperature changer" in the claims.

When the temperature of the cooling water is equal to or higher than the valve opening temperature and the first thermostat valve 72 (TS valve body 72a) is open, the cooling water flows through the main cooling water passage 62 and is cooled by the radiator 71. be. On the other hand, when the first thermostat valve 72 is closed, the flow of cooling water through the main cooling water path 62 is stopped, and cooling of the cooling water by the radiator 71 is stopped.

The main cooling water path 62 is provided with a first water temperature sensor SN3 and a second water temperature sensor SN4 that detect the temperature of the cooling water flowing through it. The first water temperature sensor SN3 is positioned between the water pump 61 and the cylinder block 3, more specifically, downstream of the water pump 61 and from the cylinder block 3 in the flow direction of the cooling water indicated by the solid arrow in FIG. is provided at a position on the upstream side, and detects the temperature of cooling water passing through this position. The second water temperature sensor SN4 is positioned between the cylinder head 4 and the radiator 71, more specifically, downstream of the cylinder head 4 and upstream of the radiator 71 with respect to the cooling water flow direction indicated by the solid arrow in FIG. It is provided at a position on the side, and detects the temperature of cooling water passing through this position. Hereinafter, the temperature of the cooling water detected by the first water temperature sensor SN3 will be referred to as the engine water temperature. Here, the temperature of the cooling water passing through the TS valve main body 72a of the first thermostat valve 72 is substantially the same as the engine water temperature detected by the first water temperature sensor SN3, and the first thermostat valve 72 is adjusted according to this engine water temperature. Open and close.

(EGR cooling water path)
The EGR cooling water path 63 is a path that bypasses part of the main cooling water path 62 .

As indicated by the dashed-dotted line arrow in FIG. 2 , part of the cooling water flowing through the block-side water jacket 62 a included in the main cooling water path 62 is introduced into the EGR cooling water path 63 . The cooling water introduced into the EGR cooling water path 63 from the block side water jacket 62a passes through the EGR cooler (EGR/C) 52, the heater core 74 for air conditioning, and the exhaust port side water jacket 63b formed in the cylinder head 4. and is returned to the water pump 61.

As shown in FIG. 3, the exhaust port-side water jacket 63b is a water jacket formed around the exhaust port 10 at a position downstream (downstream in the flow direction of the exhaust gas) of the combustion chamber-side water jacket 62b. be.

Thus, in the present embodiment, a part of the main cooling water passage 62 including the block-side water jacket 62a and the EGR cooling water passage 63 allow the water pump 61 and A path 160 is formed for circulating cooling water via the engine body 1 . In the present embodiment, the cooling water flow path 160 formed by a part of the main cooling water path 62 including the block-side water jacket 62a and the EGR cooling water path 63 is referred to as the "cooling water path" in the claims. Equivalent to.

The position between the cylinder head 4 and the water pump 61 in the EGR cooling water path 63, more specifically, the position downstream of the cylinder head 4 and the water pump 61 with respect to the flow direction of the cooling water indicated by the dashed-dotted arrow in FIG. A flow control valve (S/V) 75 is interposed at a position on the upstream side.

FIG. 4 is a schematic cross-sectional view of the flow control valve 75. As shown in FIG. FIG. 5 shows the degree of opening of the flow control valve 75 (the upper graph in FIG. 4) and the pressure of the cooling water in the EGR cooling water path 63 detected by a pressure sensor SN5 (described later) (in FIG. 4). lower graph). Note that the lower graph in FIG. 4 schematically shows changes in the pressure of the cooling water.

The flow control valve 75 is a solenoid type opening/closing valve, and includes a valve body 75a that opens and closes the EGR cooling water path 63, and a driving portion 75b that receives electric power to drive the valve body 75a. The flow control valve 75 is of a normally open type, and the valve body 75a is fully opened when the power supply to the driving portion 75b is stopped.

The driving portion 75b duty-drives the valve body 75a so that it opens and closes at a predetermined frequency. That is, the flow control valve 75 is a DUTY control valve, and as shown in FIG. 5, the valve body 75a is driven to repeat full opening and full closing. Then, one energization is performed for a period (one cycle) T obtained by combining one energization stop period, that is, the valve opening period T1 of the valve body 75a, and one energization period, that is, the valve closing period T2 of the valve body 75a. The flow rate of the cooling water passing through the valve main body 75a is changed by changing the period, that is, the DUTY ratio, which is the ratio of one valve closing period T2. The electric power supplied to the driving portion 75b of the flow control valve 75 is controlled by the CSV control device 110 provided together with the flow control valve 75 and the PCM 100 which will be described later. The CSV control device 110 receives a command from the PCM 100, which will be described later, and supplies power to the driving section 75b at the commanded period and the commanded DUTY ratio. Hereinafter, the ratio of the energization period, that is, the valve closing period T2 to one period T of the flow control valve 75 is simply referred to as the DUTY ratio of the flow control valve 75 as appropriate.

As described above, since the flow control valve 75 is of the normally open type, when the DUTY ratio of the flow control valve 75 is set to 0% and the power supply to the driving portion 75b is stopped, the valve body 75a of the flow control valve 75 is fully open. On the other hand, when the duty ratio of the flow control valve 75 is set to 100% and electric power is continuously supplied to the driving portion 75b, the valve main body 75a is kept fully closed.

Specifically, the drive unit 75b includes a coil 171 that receives power supply to generate an electromagnetic force; a drive pin 174 connected to the movable core 173 and moving integrally therewith; a retainer 175 attached to the tip of the drive pin 174; and a spring 176 that is The valve body 75a is connected to the drive pin 174 and moves integrally with the drive pin 174 and the movable core 173 . The spring 176 is arranged to bias the retainer 175 in the upward direction in FIG. 4 and in the direction in which the valve body 75a opens. When power is supplied to the coil 171, the movable core 173 is attracted to the fixed core 172 as shown in FIG. 4, and the valve body 75a is fully closed. On the other hand, when the power supply to the coil 171 is stopped, the biasing force of the spring 176 moves the retainer 175 and the valve body 75a upward in FIG. 4, and the valve body 75a is fully opened.

The EGR cooling water path 63 is provided with a pressure sensor SN5 for detecting the pressure of the cooling water flowing therethrough. The pressure sensor SN5 is positioned between the cylinder head 4 and the flow control valve 75, more specifically, downstream of the cylinder head 4 in the flow direction of the cooling water indicated by the dashed-dotted arrow in FIG. , and detects the pressure of cooling water passing through this position.

The EGR cooling water path 63 is connected to the main cooling water path 62 via a communication path 65 at a position between the heater core 74 and the flow control valve 75 . Specifically, the cylinder head 4 is formed with a communication path 65 that connects the combustion chamber side water jacket 62b and the exhaust port side water jacket 63b. In the cylinder head 4 , the EGR cooling water path 63 and the main cooling water path 62 are connected by this communication path 65 .

The valve path 66 is a path that connects the combustion chamber side water jacket 62b and a portion of the EGR cooling water path 63 between the heater core 74 and the exhaust port side water jacket 63b. A part of the cooling water in the combustion chamber side water jacket 62 b passes through the valve path 66 and joins the EGR cooling water path 63 via the throttle valve (ETB) 32 and the bypass valve (ABV) 39 .

(Cooling water path for ATF)
The ATF cooling water path 64 is a path that bypasses part of the main cooling water path 62 separately from the EGR cooling water path 63 , and connects the block-side water jacket 62 a and the water pump 61 . As indicated by the dashed arrows in FIG. 2, part of the cooling water in the block-side water jacket 62a is diverted from the main cooling water path 62 to the ATF warmer (ATF/W) 76 and the oil cooler (O/C). ) 77 and then returns to the water pump 61 . The ATF warmer 76 is a device for warming ATF (automatic transmission fluid), that is, the liquid used in the transmission, and the oil cooler 77 is a device for cooling lubricating oil supplied to the engine body 1 and the like.

In the ATF cooling water path 64, a second thermostat valve (T/S ) 78 are interposed. The second thermostat valve 78 is a thermostat valve with a fixed opening temperature.

(3) Control System FIG. 6 is a block diagram showing the engine control system. A PCM 100 shown in this figure is a microprocessor for overall control of the engine and the like, and is composed of a well-known CPU, ROM, RAM and the like.

Detection signals from various sensors are input to the PCM 100 . For example, the PCM 100 is electrically connected to the aforementioned crank angle sensor SN1, airflow sensor SN2, first water temperature sensor SN3, second water temperature sensor SN4, and pressure sensor SN5. Information detected by these sensors (that is, crank angle, engine speed, intake flow rate, engine water temperature, cooling water temperature at the outlet of the cylinder head 4, and cooling water pressure) is sequentially input to the PCM 100 . The vehicle is also provided with an accelerator pedal sensor SN6 that detects the opening of an accelerator pedal operated by the driver of the vehicle.

The PCM 100 controls each section of the engine while executing various determinations and calculations based on input information from each sensor. The PCM 100 includes an injector 15, a spark plug 16, a throttle valve 32, an electromagnetic clutch 34, a bypass valve 39, an EGR valve 53, a water pump 61, a thermostat heater 72b (first thermostat valve 72), and a CSV controller 110 (flow control valve 75). ), etc., and outputs control signals to each of these devices based on the results of the above calculations and the like.

The PCM 100 functionally includes a combustion control unit 101, a cooling water control unit 102, and a failure determination unit 103 by executing a predetermined program. This PCM 100 corresponds to "control means" in the claims.

The combustion control unit 101 is a control module that controls combustion of the air-fuel mixture in the combustion chamber 6 . The cooling water control unit 102 is a control module that controls the cooling device 60 . The failure determination unit 103 is a control module that determines whether or not the flow control valve 75 is out of order.

(3-1) Normal control (combustion control section)
The combustion control unit 101 performs the following control during normal times when it is not determined that the flow control valve 75 is out of order.

The combustion control unit 101 controls each part of the engine (injector 15, spark plug 16, etc.) so that the engine output becomes an appropriate value according to the driver's request. Specifically, the combustion control unit 101 calculates a required output, which is a required value of the engine output, based on the degree of opening of the accelerator pedal detected by the accelerator pedal sensor SN6. Further, the combustion control unit 101 sets the engine output guard value, which is the upper limit value of the engine output, to a preset first guard value.

Combustion control unit 101 compares the calculated required output and the engine output guard value, and sets the smaller value among them as the target output. Next, the combustion control section 101 calculates the amount of air and the amount of fuel to be introduced into the combustion chamber 6 in order to achieve this target output. The combustion control unit 101 then drives the throttle valve 32 and the injector 15 so that the calculated air amount and fuel amount are introduced into the combustion chamber 6 .

Here, the first guard value is set to a value sufficiently larger than the maximum value of the required output, that is, the required output when the accelerator pedal is fully opened. As a result, when the flow control valve 75 is not determined to be malfunctioning, the target output is set to the required output, and the throttle valve 32 and the injector 15 are driven so as to achieve the required output.

Further, in the present embodiment, the combustion control unit 101 controls the ignition timing of the spark plug 16, the opening of the EGR valve 53, etc. so that SPCCI combustion is realized in the low speed region and SI combustion is realized in the high speed region. change.

(cooling water controller)
The cooling water control unit 102 controls the first thermostat valve 72 and the flow control valve 75 as follows during normal operation when the flow control valve 75 is not out of order.

The cooling water control unit 102 determines the opening temperature of the first thermostat valve 72 and changes the amount of electricity supplied to the thermostat heater 72b of the first thermostat valve 72 .

The cooling water control unit 102 switches the opening temperature of the first thermostat valve 72 between the first temperature and the second temperature, which is lower than the first temperature, according to the wall temperature of the combustion chamber 6 . Specifically, when the wall temperature of the combustion chamber 6 is less than the predetermined reference wall temperature, the cooling water control unit 102 sets the valve opening temperature of the first thermostat valve 72 to the first temperature, The amount of electricity supplied to the thermostat heater 72b is adjusted so that the temperature corresponds to this temperature. On the other hand, when the wall temperature of the combustion chamber 6 is equal to or higher than the reference wall temperature, the cooling water control unit 102 sets the valve opening temperature of the first thermostat valve 72 to the second temperature, and the temperature of the thermostat heater 72b corresponds to this. The amount of power supplied to the thermostat heater 72b is adjusted so that the temperature becomes the same. As a result, when the engine water temperature is less than the first temperature and the warm-up of the engine body 1 is not completed, the cooling water cooled by the radiator 71 is prohibited from being supplied to the engine body 1. 1 is accelerated to warm up. On the other hand, when the engine water temperature rises to the first temperature or higher and the warm-up of the engine body 1 is completed, the cooling water cooled by the radiator 71 is started to be supplied to the engine body 1, and the engine is cooled by the cooling water. Cooling of the main body 1 is started. However, when the wall temperature of the combustion chamber 6 is equal to or higher than the reference wall temperature, the first thermostat valve 72 is opened and cooled by the radiator 71 if the engine water temperature is equal to or higher than the second temperature even if the temperature is lower than the first temperature. Then, the cooling water is supplied to the engine body 1 .

The first temperature and the second temperature are preset and stored in the PCM 100 . For example, the first temperature is set to approximately 90°C, and the second temperature is set to approximately 80°C. The reference wall temperature is a temperature at which SPCCI combustion is appropriately achieved, and is set to the wall temperature of the combustion chamber 6 when the engine coolant temperature is approximately 120°C, for example, 116°C.

An estimated value is used for the wall temperature of the combustion chamber 6 that serves as a reference for switching between the first temperature and the second temperature. The cooling water control unit 102 estimates the wall temperature of the combustion chamber 6 based on the cooling water temperature detected by the second water temperature sensor SN4.

The cooling water control unit 102 determines the duty ratio of the flow control valve 75 and issues a command to the CSV control device 110 so that the flow control valve 75 (valve body 75a) is opened and closed at this duty ratio.

When the engine water temperature is less than the first temperature and the warm-up of the engine body 1 is not completed, the cooling water control unit 102 prohibits the flow control valve 75 from opening and sets its duty ratio to 100%. The flow control valve 75 is kept fully closed.

On the other hand, when the engine water temperature is equal to or higher than the first temperature, opening and closing of the flow control valve 75 is permitted. At this time, the cooling water control unit 102 determines the duty ratio of the flow control valve 75 so that the wall temperature of the combustion chamber 6 becomes the target wall temperature, which is the target value. An estimated value is also used for the wall temperature of the combustion chamber 6 . The target wall temperature is preset and stored in the cooling water control unit 102 . In this embodiment, the target wall temperature is set to a temperature equal to or lower than the reference wall temperature.

Specifically, when the wall temperature of the combustion chamber 6 is higher than the target wall temperature, the cooling water control unit 102 reduces the DUTY ratio of the flow control valve 75 to lengthen the valve opening period T1 of the flow control valve 75. do. As the valve opening period T1 of the flow control valve 75 becomes longer, the flow rate of the cooling water flowing through the block-side water jacket 62a and the exhaust port-side water jacket 63b included in the EGR cooling water path 63 in which the flow control valve 75 is arranged. will increase. As a result, the cooling of the engine body 1 is promoted and the wall temperature of the combustion chamber 6 is lowered. On the other hand, when the wall temperature of the combustion chamber 6 is lower than the target wall temperature, the cooling water control unit 102 increases the DUTY ratio of the flow control valve 75, shortens the valve opening period T1 of the flow control valve 75, and blocks it. The cooling water flowing through the side water jacket 62a and the exhaust port side water jacket 63b is lowered. As a result, the cooling of the engine body 1 is suppressed and the wall temperature of the combustion chamber 6 rises.

Here, as described above, the valve opening temperature of the second thermostat valve 78 is fixed, and the second thermostat valve 78 opens when the engine coolant temperature reaches or exceeds a predetermined temperature regardless of the operating state of the engine. The opening temperature of the second thermostat valve 78 is set to a temperature lower than the first temperature, eg, 50.degree.

With the above configuration, when the engine is started with the engine water temperature lower than the valve opening temperature of the second thermostat valve 78, that is, when the engine is cold started, the first and second Thermostat valve 78 and flow control valve 75 are all kept closed. As a result, cooling of the engine body 1 by cooling water is not performed, and warming up of the engine body 1 is promoted. When the warm-up of the engine body 1 progresses and the engine water temperature reaches or exceeds the opening temperature of the second thermostat valve 78, the second thermostat valve 78 opens. As a result, the cooling water flows through the ATF cooling water path 64, and the cooling water heated in the block-side water jacket 62a is introduced into the ATF warmer 76 to warm the ATF. When the temperature of the coolant further rises to the first temperature or higher, that is, when the engine body 1 is completely warmed up, the second thermostat valve 78 opens. As a result, cooling of the cooling water by the radiator 71 is started as described above, and cooling of the engine body 1 by this cooled cooling water is started. When the cooling water reaches the first temperature or higher, the flow control valve 75 is permitted to open, and the flow control valve 75 is opened and closed so that the wall temperature of the combustion chamber 6 reaches the target wall temperature.

(failure determination unit)
A procedure for failure determination of the flow control valve 75 performed by the failure determination unit 103 will be described with reference to the flowchart of FIG. 7 .

First, in step S1, the failure determination unit 103 reads values detected by each sensor. The failure determination unit 103 reads the temperature of the cooling water detected by the first water temperature sensor SN3, that is, the engine water temperature, the pressure of the cooling water detected by the pressure sensor SN5, and the like.

Next, in step S2, the failure determination unit 103 determines whether or not a valve closing command has been issued to the flow control valve 75 to switch from the open state to the closed state. On the other hand, it is determined whether or not the state in which a command to stop energization has been issued has changed to the state in which a command to energize is issued. The failure determination unit 103 makes this determination based on a command issued from the cooling water control unit 102 to the CSV control device 110 .

If the determination in step S2 is NO and the valve closing command is not issued to the flow control valve 75, the process ends (returns to step S1). On the other hand, if this determination is YES and a valve closing command has been issued to the flow control valve 75, the process proceeds to step S3.

In step S3, the failure determination unit 103 calculates the amount of increase in the pressure of the cooling water in the EGR cooling water path 63 due to the closing of the flow control valve 75, and sets it to the determination amount used in step S4, which will be described later. do. When the flow control valve 75 is closed, the cooling water is dammed by the flow control valve 75 . At this time, the cooling water in the EGR cooling water path 63 collides with the flow control valve 75, piping, etc. due to its inertia, and a so-called water hammer phenomenon occurs. Accordingly, as shown in FIG. 5, when the flow control valve 75 is closed (at time t1 or the like), the pressure in the EGR cooling water path 63 rapidly increases from P1 to P2. In step S3, the amount of pressure increase is calculated. Specifically, the pressure detected by the pressure sensor SN5 at the timing when the flow control valve 75 is instructed to close (the timing when the flow control valve 75 is energized). , the pressure detected by the pressure sensor SN5 at the timing just before the command to close the flow control valve 75 (the timing just before the command to start energizing the flow control valve 75) is subtracted. A value is calculated as the amount of pressure increase described above. Then, this calculated value is determined as the determination amount. After step S3, the process proceeds to step S4.

In step S4, the failure determination unit 103 determines whether or not the determination amount (pressure increase amount) is equal to or less than a preset determination threshold. The determination threshold value is preset to a value greater than 0 and stored in the failure determination unit 103 .

If the determination in step S4 is NO and the determination amount is larger than the determination threshold value, the process ends (returns to step S1). On the other hand, if the determination in step S5 is YES and the determination amount is equal to or less than the determination threshold, the process proceeds to step S5. In step S5, the abnormality counter is counted up. The abnormality counter is a counter that is incremented by 1 when the determination in step S4 becomes NO, and is reset to 0 when the engine stops. After step S5, the process proceeds to step S6.

In step S6, the failure determination unit 103 determines whether or not the abnormality counter is greater than the preset number of times of abnormality determination. If the determination in step S6 is YES and the abnormality counter is greater than the number of times of abnormality determination, the failure determination unit 103 proceeds to step S7 and determines that the flow control valve 75 is abnormal, that is, is out of order. . On the other hand, if the determination in step S6 is NO and the abnormality counter is equal to or less than the number of times of abnormality determination, the failure determination unit 103 ends the process (returns to step S1). It should be noted that the number of abnormality determinations is preset to a value greater than 0 and stored in the failure determination unit 103 .

As described above, in the present embodiment, whether or not the flow control valve 75 is abnormal (whether it is out of order) is determined based on the pressure change in the EGR cooling water path 63 that occurs when the flow control valve 75 is opened and closed. When it is judged and the abnormality counter becomes larger than the number of times of abnormality judgment, the failure of the flow control valve 75 is detected. That is, as described above, if the flow control valve 75 is normally opened and closed, the water hammer phenomenon occurs and the cooling water pressure increases. is almost unchanged. From this, in the present embodiment, when the determination amount is equal to or less than the determination threshold, it is estimated that the flow control valve 75 is likely not normally opening and closing, and the number of times the determination amount becomes equal to or less than the determination threshold is determined. If the number of times is exceeded, it is judged to be abnormal.

(3-2) Control when the flow control valve fails Next, the control of the combustion control unit 101 and the cooling water control unit 102 when the failure determination unit 103 determines that the flow control valve 75 has failed will be described with reference to FIG. 8 and the flow charts of FIGS.

In step S11, the cooling water control unit 102 determines whether or not the failure determination unit 103 has determined that the flow control valve 75 is abnormal. In this embodiment, as described above, if the determination in step S6 is YES and the abnormality counter is greater than the number of times of abnormality determination, it is determined that the flow control valve 75 is abnormal. is also determined as YES. On the other hand, if the determination in step S6 is NO and the abnormality counter is equal to or less than the number of times of abnormality determination, it is not determined that the flow control valve 75 is abnormal, and accordingly the determination in step S11 is also NO. .

If the determination in step S11 is NO and it is not determined that the flow control valve 75 is abnormal, the process proceeds to step S12. In step S<b>12 , the cooling water control unit 102 controls the flow rate control valve 75 during normal operation. That is, when the engine water temperature is less than the first temperature, the flow control valve 75 is kept fully closed, and when the engine water temperature is equal to or higher than the first temperature, the flow control valve is adjusted so that the wall temperature of the combustion chamber 6 reaches the target wall temperature. 75.

On the other hand, if the determination in step S11 is YES and it is determined that the flow control valve 75 is abnormal, the process proceeds to step S13. In step S13, the cooling water control unit 102 continuously stops energizing the flow control valve 75 for a predetermined period. The de-energization of the flow rate control valve 75 is performed for a period longer than at least one period T described above. When the flow rate control valve 75 is de-energized, the spring 176 urges the valve body 75a toward the valve opening side. That is, in step S13, the cooling water control unit 102 issues a command to the flow control valve 75 so that it is fully opened.

After step S13, the process proceeds to step S14. In step S14, it is determined whether or not the amount of decrease in the engine water temperature after stopping the energization of the flow control valve 75 is greater than the determination amount of decrease. The determination decrease amount is preset to a value greater than 0 and stored in the cooling water control unit 102 .

If the determination in step S14 is YES and the amount of decrease in the engine water temperature after stopping the energization of the flow control valve 75 is larger than the determination amount of decrease, the process proceeds to step S15.

In step S15, the cooling water control unit 102 cancels the de-energization of the flow rate control valve 75 and returns the control thereof to normal control.

The valve main body 75a of the flow control valve 75 is stuck in the closing side state (fully closed state, or a state between fully closed and fully open), and it is determined that the flow control valve 75 is abnormal. In some cases, stopping the energization of the flow control valve 75 may cause the valve main body 75a to be released from the fixation. Specifically, when the energization of the flow control valve 75 is stopped, the biasing force of the spring 176 is applied to the valve body 75 a of the flow control valve 75 . As a result, the valve main body 75a tries to move vigorously toward the valve opening side, so that the fixation of the valve main body 75a may be released. When the valve body 75a is released from the closed state and is fully opened, the flow rate of the cooling water passing through the flow control valve 75 and thus the flow rate of the cooling water flowing through each of the cooling water paths 62 to 66 of the cooling device 60. and the flow rate of the cooling water passing through the radiator 71 increases, and the temperature of the cooling water drops.

Also, as shown in FIG. 10, foreign matter X1 and foreign matter X2 adhere to the periphery of the valve body 75a of the flow control valve 75, and these foreign matter X1 and X2 get caught between the valve body 75a and the inner wall of the passage. If the valve main body 75a does not open and close properly as a result, and if it is determined that the flow control valve 75 is abnormal, the flow control valve 75 is de-energized and the vicinity of the flow control valve 75 is stopped. Foreign matter may be removed by passing a large amount of cooling water over a relatively long period of time. Also in this case, the flow rate of the cooling water increases as the foreign matter is removed, and the temperature of the cooling water decreases.

Therefore, when the amount of decrease in the engine water temperature after the power supply to the flow control valve 75 is stopped becomes larger than the determination decrease amount, the flow control valve 75 is released or the foreign matter is removed. It is thought that Therefore, in the present embodiment, if the determination in step S14 is YES, it is assumed that the flow control valve 75 can be properly opened and closed, and the control of the flow control valve 75 is changed to normal control in step S15. return.

On the other hand, if the amount of decrease in the engine water temperature after stopping the supply of electricity to the flow control valve 75 is equal to or less than the determination decrease amount, it is presumed that the fixation was not released or the foreign matter was not removed. Accordingly, if the determination in step S15 is NO, the process proceeds to step S16 to perform the failure control.

FIG. 9 is a flow chart showing the procedure of failure control.

When the failure control is started, first, in step S21, the cooling water control unit 102 reduces the valve opening temperature of the first thermostat valve 72 . In this embodiment, this valve opening temperature is changed to a third temperature lower than the second temperature. Specifically, the cooling water control unit 102 increases the amount of electricity supplied to the thermostat heater 72b so that the first thermostat valve 72 opens when the temperature of the cooling water is equal to or higher than the third temperature. After step S21, the process proceeds to step S22.

The third temperature is preset and stored in the cooling water control unit 102 . In this embodiment, the third temperature is set to a temperature lower than the lower limit of the temperature of the cooling water that can be taken while the engine is running. Accordingly, the first thermostat valve 72 is opened. Note that the third temperature may be set to a temperature higher than the lower limit (but lower than the first temperature) or a second temperature. When the first thermostat valve 72 opens, the cooling water passes through the main cooling water path 62 and is cooled by the radiator 71, and the temperature of the cooling water drops.

In step S22, the cooling water control unit 102 determines whether or not the engine water temperature is equal to or lower than the failure target temperature. The failure target temperature is preset and stored in the cooling water control unit 102 . For example, the failure target temperature is the cooling water that can keep the temperature of the engine body 1 below a predetermined temperature (for example, a temperature at which overheating does not occur) even when the flow control valve 75 is stuck in the closed state. The temperature is set slightly lower than the upper temperature limit.

If the determination in step S22 is NO and the engine coolant temperature is higher than the failure target temperature, the process proceeds to step S23. In step S23, the combustion control unit 101 limits the engine output and ends the process (returns to step S1). In this embodiment, the combustion control unit 101 sets the engine output guard value to a second guard value smaller than the first guard value, thereby limiting the engine output.

Specifically, the second guard value is set to a value smaller than the required output when the accelerator pedal is fully opened. As in the normal case, even when the flow control valve 75 fails, the combustion control unit 101 compares the required output and the engine output guard value, and sets the smaller of them as the target output. Therefore, when the engine output guard value is set to the second guard value, the target output is set to the second guard value which is smaller than the required output, that is, the normal target output, even if the accelerator pedal is fully opened. . The combustion control unit 101 drives the throttle valve 32 and the injector 15 so as to achieve the target output, thereby reducing the engine output from the normal engine output.

On the other hand, if the determination in step S22 is YES and the engine coolant temperature is equal to or lower than the failure target temperature, the process proceeds to step S24. In step S24, the combustion control unit 101 cancels the restriction on the engine output and ends the process (returns to step S1). Specifically, combustion control unit 101 returns the engine output guard value to the first guard value. It should be noted that the power supply to the flow control valve 75 is continuously stopped while the failure control is being performed.

(4) Operation, etc. As described above, in the present embodiment, when it is determined that the flow control valve 75 is out of order, the power supply to the flow control valve 75 is stopped so that the flow control valve 75 is fully opened. driven by As a result, as described above, it is possible to increase the flow rate of the cooling water passing through the flow control valve 75 and remove foreign matter attached around the flow control valve 75 with a large amount of cooling water. Further, by moving the flow control valve 75 vigorously to the fully open side, it becomes possible to release the fixation of the flow control valve 75 . Therefore, it is possible to restore the flow control valve 75 to normal. Moreover, even if the flow control valve 75 does not open and close appropriately, it is possible to avoid further reduction in the flow rate of the cooling water that passes through the flow control valve 75 and circulates through the engine body 1 . Therefore, excessive temperature rise of the engine body 1 can be prevented. Since the excessive temperature rise of the engine body 1 can be prevented by controlling the flow rate control valve 75 in this way, the chances of restricting the engine output in order to prevent this excessive temperature rise can be reduced, and the engine output can be reduced. can be secured.

In particular, in this embodiment, the flow rate control valve 75 is of a normally open type, and the valve main body 75a is driven to the valve opening side by stopping the energization thereof. Therefore, by stopping the energization of the flow control valve 75, the flow control valve 75 can be opened more reliably.

In addition, in this embodiment, when it is determined that the flow control valve 75 is out of order, the engine output is limited, so that the excessive temperature rise of the engine body 1 can be prevented more reliably. . Here, as described above, in this embodiment, the chances of engine output being limited can be reduced. Therefore, it is possible to prevent an excessive temperature rise of the engine body 1 more reliably and avoid a significant decrease in the engine output.

Further, in this embodiment, when it is determined that the flow control valve 75 is out of order, the opening temperature of the first thermostat valve 72 is reduced to open the first thermostat valve 72 . Therefore, the cooling water can be surely introduced into the radiator 71 to cool the engine body 1, and the cooling water can sufficiently cool the engine body 1, thereby further reliably preventing the engine body 1 from overheating.

Here, since the engine water temperature can be lowered by reducing the valve opening temperature of the first thermostat valve 72, when the engine water temperature falls below the failure target temperature, even if the engine output limit is released, the engine body 1 will not overheat. Temperature rise can be prevented. On the other hand, as described above, in this embodiment, when the engine water temperature becomes equal to or lower than the failure target temperature, the engine output limitation is lifted. Therefore, a high engine output can be realized while preventing excessive temperature rise of the engine body 1 .

Further, in the present embodiment, whether or not the flow control valve 75 is out of order is determined based on the pressure change occurring in the EGR cooling water path 63 in which the flow control valve 75 is arranged when the flow control valve 75 is opened and closed. Judging. As shown in FIG. 5, the cooling water pressure changes sensitively as the flow control valve 75 is opened and closed. Therefore, by determining whether or not the flow control valve 75 is out of order based on the pressure change of the cooling water, it is possible to perform this determination quickly and accurately.

Further, in this embodiment, the duty ratio of the flow control valve 75 is set so that the wall temperature of the combustion chamber 6 becomes the target wall temperature, and the flow control valve 75 is set so that the wall temperature of the combustion chamber 6 becomes the target wall temperature. 75 is opened and closed. Therefore, the wall temperature of the combustion chamber 6 can be more reliably brought to a temperature suitable for combustion. In particular, in SPCCI combustion, it is necessary to compressively ignite part of the air-fuel mixture, and it is required to control the wall temperature of the combustion chamber 6 with high accuracy. In contrast, according to the present embodiment, the wall temperature of the combustion chamber 6 can be accurately controlled to an appropriate temperature, and appropriate SPCCI combustion can be achieved.

(5) Modification In the above embodiment, the engine output is limited by reducing the engine output guard value, that is, the engine output is reduced only when the accelerator pedal opening is large and the required output is high. However, instead of this, the engine output may be limited by changing the engine output to a value smaller than the required output regardless of the magnitude of the required output.

In the above embodiment, the control for limiting the engine output when the flow control valve 75 fails and the control for lowering the opening temperature of the first thermostat valve 72 when the flow control valve 75 fails may be omitted. . Alternatively, the configuration may be such that only one of these controls is performed.

In the above embodiment, the wall temperature of the combustion chamber 6 is estimated based on the information from the second water temperature sensor SN4, but the configuration for acquiring the wall temperature of the combustion chamber 6 is not limited to this. For example, the engine body 1 may be provided with a sensor that directly detects the wall temperature of the combustion chamber 6 .

Specific numerical values such as the first temperature and the second temperature shown in the above embodiment are merely examples. These temperatures can be changed as appropriate according to the specific configurations of the engine body 1 and the cooling device 60 .

In the above embodiment, an example in which the cooling device 60 is applied to an engine capable of partial compression ignition combustion (SPCCI combustion) has been described, but the combustion mode of the engine to which the cooling device 60 is applied is not limited to this. For example, the cooling device 60 can also be applied to an engine that is controlled so that the combustion mode in the entire operating range is SI combustion.

1 engine body 6 combustion chamber 60 cooling device 61 water pump 62 main cooling water path (radiator side cooling water path)
71 radiator 72a TS valve body (valve body of thermostat valve)
72b Thermostat heater 72b (valve opening temperature changing unit)
72 first thermostat valve (thermostat valve)
75 flow control valve 100 PCM (control means)
160 cooling water path (first cooling water path)
SN5 pressure sensor

Claims (5)

An engine cooling device,
a cooling water path for circulating cooling water through the engine body;
a flow control valve capable of opening and closing the cooling water path;
and a control means for controlling the flow control valve,
The flow rate control valve is configured to open and close when supplied with electric power, and fully open when the supply of electric power is stopped,
The control means determines whether or not the flow control valve is out of order, and when it is determined that the flow control valve is out of order, the flow control valve is kept fully open for at least a predetermined period. An engine cooling device, characterized in that the power supply to the flow control valve is stopped immediately. The engine cooling device according to claim 1 ,
The engine cooling device, wherein the control means limits the output of the engine when it is determined that the flow rate control valve is out of order. The engine cooling device according to claim 1 or 2 ,
a radiator for cooling cooling water;
a radiator-side cooling water path, which is a path for circulating cooling water through the engine body, and diverts the cooling water from the cooling water path to pass through the radiator;
A valve body disposed in the middle of the radiator-side cooling water path is opened when the temperature of the cooling water passing through the valve body is equal to or higher than a predetermined valve opening temperature, and the temperature of the cooling water increases to the opening temperature. further comprising a thermostat including a valve body that closes when the temperature is less than the valve temperature, and a valve opening temperature changing unit that can change the valve opening temperature,
The engine cooling device, wherein the control means controls the valve opening temperature changer so that the valve opening temperature of the thermostat is lowered when it is determined that the flow control valve is out of order. The engine cooling device according to any one of claims 1 to 3 ,
a pressure sensor arranged in the middle of the cooling water path and detecting the pressure of the cooling water passing through the cooling water path;
The engine cooling device according to claim 1, wherein the control means determines whether or not the flow control valve is out of order based on the detected value of the pressure sensor when the flow control valve is opened or closed. In the engine cooling device according to any one of claims 1 to 4 ,
The engine cooling device, wherein the control means opens and closes the flow control valve so that the wall temperature of a combustion chamber formed in the engine body reaches a preset target temperature.

Images