JP2020176582A - Engine cooling device - Google Patents

Abstract

To provide an engine cooling device which prevents a temperature of an engine body from becoming excessively high while inhibiting reduction of an engine output.SOLUTION: An engine cooling device includes: a coolant path 160 in which a coolant is circulated via an engine body 1; a flow control valve 75 which may open or close the coolant path 160; and control means 100 which controls the flow control valve 75. The control means 100 is configured to control the flow control valve 75 to keep the flow control valve 75 in a fully opened state for at least a predetermined period when the control means 100 determines whether the flow control valve 75 is broken and it is determined that the flow control valve 75 is broken.SELECTED DRAWING: Figure 2

Description

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

An engine installed in a vehicle or the like is configured such that cooling water is pumped to the engine body and auxiliary machinery by a water pump that is rotationally driven by the engine. Further, a flow rate control valve that can be opened and closed 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 for opening and closing this passage is provided in the middle of a passage connecting the engine body and the radiator and the cooling water flows inside, and the opening degree of the flow control valve is changed. As a result, an engine is disclosed in which the flow rate of the cooling water flowing through the passage and 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.

Japanese Unexamined Patent Publication No. 2018-168753

In an engine provided with a flow rate control valve as described above, if the flow rate control valve fails, an appropriate amount of cooling water cannot be 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, since the engine output is reduced due to the failure of the flow control valve, it is considered that the temperature of the engine body can be prevented from becoming excessively high. However, in this engine, since the excessive temperature rise of the engine body is avoided only by limiting the engine output, it is necessary to significantly reduce the engine output and the engine performance is significantly deteriorated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent the temperature of the 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, a cooling water path for circulating cooling water via the engine body, a flow rate control valve capable of opening and closing the cooling water path, and the above. A control means for controlling the flow rate control valve is provided, and the control means determines whether or not the flow rate control valve is out of order, and when it is determined that the flow rate control valve is out of order, the flow rate control valve is provided. Controls the flow control valve so that the flow rate control valve is fully opened continuously for at least a predetermined period of time.

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 rate control valve fails, the flow rate of the cooling water that passes through the flow rate control valve and passes through the engine body may be increased, and the engine body can be prevented from overheating. By controlling the flow control valve to suppress the overheating of the engine body, it is possible to reduce the chance of limiting the engine output in order to prevent the overheating, and to secure the engine output. It will be possible.

Further, when it is determined that the flow rate control valve has failed due to the adhesion of foreign matter around the flow rate control valve, it is possible to increase the flow rate passing through the flow rate control valve to remove the foreign matter. Therefore, the flow rate control valve can be returned to normal without reducing the engine output, and the engine performance can be improved.

In the above configuration, preferably, the flow rate control valve is configured to open and close in response to the supply of electric power and to be fully opened when the supply of the electric power is stopped, and the control means is configured such that the flow rate control valve fails. When it is determined that this is the case, the power supply to the flow control valve is stopped (claim 2).

According to this configuration, the flow control valve can be easily maintained open.

In the configuration, preferably, the control means limits the output of the engine when it determines that the flow control valve is out of order (claim 3).

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, so that even in this configuration, the engine output The limit amount can be reduced to suppress the deterioration of engine performance.

In the above configuration, preferably, a radiator for cooling the cooling water and a path for circulating the cooling water via the engine main body, and the cooling water is separated from the cooling water path and passed through the radiator for cooling on the radiator side. A valve body arranged in the middle of the water path and the radiator side cooling water path, and the cooling water is opened when the temperature of the cooling water passing through the valve body is equal to or higher than the predetermined valve opening temperature. The control means further includes a thermostat including a valve body that closes the valve when the temperature is lower than the valve opening temperature and a valve opening temperature changing portion that can change the valve opening temperature, and the control means fails the flow control valve. When it is determined that the thermostat is operating, the valve opening temperature changing unit is controlled so that the valve opening temperature of the thermostat is lowered (claim 4).

In this configuration, when it is determined that the flow control valve is out of order, the thermostat valve body is opened when the thermostat valve opening temperature is reduced and the cooling water temperature is low. That is, the opportunity or time for the cooling water to pass through the second cooling water path in which the thermostat is arranged and the cooling water to be cooled by the radiator is increased. 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 prevented from becoming excessively high.

In the above configuration, preferably, the 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 is the control means 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 5).

According to this configuration, it is determined whether or not the flow rate control valve has failed based on the pressure change that changes sensitively to the change in the flow rate of the cooling water. Therefore, whether or not the flow rate control valve has failed. 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 becomes a preset target temperature (claim 6).

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 engine output.

It is a system diagram which shows schematic the whole structure of the engine to which this invention is applied. It is a circuit diagram which shows the whole structure of the cooling system of an engine schematicly. It is the schematic sectional drawing which shows the main part of the engine body. It is the schematic sectional drawing of the flow rate control valve. It is a figure which showed the opening degree change of the flow rate control valve and the pressure change of the cooling water accompanying this. It is a block diagram which shows the control system of an engine. It is a flowchart which shows the procedure of failure determination of a flow rate control valve. It is a flowchart which shows the control procedure at the time of failure of a flow control valve. It is a flowchart which shows the procedure of control at the time of failure. It is the schematic sectional drawing of the flow rate control valve when foreign matter adheres.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(1) Overall Configuration of Engine FIG. 1 is a diagram showing a preferred embodiment of a vehicle engine (hereinafter, simply referred to as an engine) to which the control device of the present invention is applied. The engine shown in FIG. 1 is a 4-cycle gasoline direct injection engine mounted on a vehicle as a power source for traveling, and includes an engine body 1, an intake passage 30 through which intake air introduced into the engine body 1 flows, and an intake passage 30. It includes an exhaust passage 40 through which the exhaust gas discharged from the engine body 1 flows, and an external EGR device 50 that returns a part of the exhaust gas flowing through the exhaust passage 40 to the intake passage 30.

The engine body 1 is slidably inserted into the cylinder block 3 in which the cylinder 2 is formed, the cylinder head 4 attached to the upper surface of the cylinder block 3 so as to close the cylinder 2 from above, and the cylinder 2. It has a cylinder 5 and a cylinder 5. The engine body 1 is typically a multi-cylinder type having a plurality of (for example, four) cylinders 2, but for simplification, the description will be given focusing on only one cylinder 2.

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 described later. Then, the supplied fuel burns while being mixed with air in the combustion chamber 6, and the piston 5 reciprocates in the vertical direction in response to the expansion force generated by the combustion.

Below the piston 5, a crankshaft 7, which is an output shaft of the engine body 1, is provided. The crankshaft 7 is connected to the piston 5 via a connecting rod 8 and is rotationally driven around the central axis in response to the reciprocating motion (vertical motion) of the piston 5.

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

The cylinder head 4 has an intake port 9 for introducing the air supplied from the intake passage 30 into the combustion chamber 6, and an exhaust port 10 for leading the exhaust gas generated in the combustion chamber 6 to the exhaust passage 40. An intake valve 11 that opens and closes the opening of the intake port 9 on the combustion chamber 6 side and an exhaust valve 12 that opens and closes the opening of the exhaust port 10 on the combustion chamber 6 side are provided. The intake valve 11 and the exhaust valve 12 are opened and closed in conjunction with the rotation of the crankshaft 7 by a valve operating mechanism including a pair of camshafts and the like arranged on the cylinder head 4.

The cylinder head 4 has an injector 15 that injects fuel (gasoline) into the combustion chamber 6 and a spark plug 16 that ignites an air-fuel mixture in which the fuel injected from the injector 15 into the combustion chamber 6 and the intake air are mixed. It 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. In the intake passage 30, in order from the upstream side, an air cleaner 31 that removes foreign matter in the intake air, a throttle valve 32 that can be opened and closed to adjust the flow rate of the intake air, and a supercharger 33 that sends out the intake air while compressing it are excessive. An intercooler 35 for cooling the intake air compressed by the turbocharger 33 and a surge tank 36 are provided. An air flow sensor SN2 for detecting the flow rate of intake air is provided at a portion of the intake passage 30 between the air cleaner 31 and the throttle valve 32.

The supercharger 33 is a mechanical supercharger (supercharger) that is mechanically linked to the engine body 1 via an electromagnetic clutch 34. As the turbocharger 33, any known turbocharger such as a Rishorum type, a roots type, or a centrifugal type can be used.

The intake passage 30 is provided with a bypass passage 38 for bypassing the supercharger 33. The bypass passage 38 connects the surge tank 36 and the EGR passage 51, which will 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 a particulate matter (PM) contained in the exhaust gas. It has a built-in GPF (gasoline particulate filter) 41b for collecting exhaust gas.

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 to each other. The EGR cooler 52 cools the exhaust gas returned 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 and 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 that compresses and ignites a part of the air-fuel mixture is carried out in a low-speed region where the engine speed is equal to or less than a predetermined speed, and compression ignition of the air-fuel mixture is appropriately realized. As described above, the geometric compression ratio of the cylinder 2 is set to a relatively high value as described above.

SPCCI combustion is partial compression ignition combustion that combines SI combustion and CI combustion. SI combustion is a combustion mode in which the air-fuel mixture is ignited by sparks generated from the spark plug 16 and the air-fuel mixture is forcibly burned by flame propagation that expands the combustion region from the ignition point to the surroundings. CI combustion is a combustion form in which the air-fuel mixture is burned by self-ignition in an environment where the temperature and pressure are sufficiently increased by compression of the piston 5. SPCCI combustion, which is a combination of these SI combustion and CI combustion, is the SI combustion of a 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 the other air-fuel mixture in the combustion chamber 6 is CI-combusted by self-ignition later (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 spark plug 16, and the remaining air-fuel mixture is compressed by the thermal energy generated by this combustion. Ignite. "SPCCI" is an abbreviation for "Spark Controlled Compression Ignition". On the other hand, in the present embodiment, general SI combustion is carried out in a high-speed region where the engine speed is higher than 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 of 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. , EGR cooling water path 63, ATF cooling water path 64, communication path 65, valve path 66).

The water pump 61 is a pump for discharging cooling water, and is assembled on 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 the cooling water, and the cooling water is cooled by the running wind of the vehicle or the like when passing through the radiator 71.

(Main cooling water path)
As shown by the solid line arrow in FIG. 2, the main cooling water path 62 allows the cooling water discharged from the water pump 61 to be supplied to the block-side water jacket 62a formed in the cylinder block 3 and the combustion chamber formed in the cylinder head 4. It is a path for circulating so as to return to the water pump 61 via the side water jacket 62b and the radiator 71. The main cooling water path 62 corresponds to the "radiator side cooling water path" of the claim.

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 each valve seat portion of the intake port 9 and the exhaust port 10. is there.

The position between the radiator 71 and the water pump 61 in the main cooling water path 62, specifically, the flow direction of the cooling water indicated by the solid line arrow in FIG. 2 is on the downstream side of the radiator 71 and upstream of the water pump 61. 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 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 is equal to or higher than a predetermined valve opening temperature. A TS valve main body 72a that sometimes opens (fully opens) and closes (fully closes) when the temperature of the cooling water is lower than the valve opening temperature is provided. 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 larger the amount of electricity supplied to the thermostat heater 72b, the lower the valve opening temperature. That is, when the amount of electricity 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 electricity supplied to the thermostat heater 72b is small and the temperature of the thermostat heater 72b is low. The TS valve body 72a opens at the timing. The amount of electricity supplied to the thermostat heater 72b is controlled by the PCM 100 described later. The first thermostat valve 72 corresponds to the "thermostat valve" of the claim. Further, the TS valve body 72a corresponds to the "valve body of the thermostat valve" of the claim, and the thermostat heater 72b corresponds to the "valve opening temperature changing part" of the claim.

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 main body 72a) is open, the cooling water flows through the main cooling water path 62 and is cooled by the radiator 71. To. On the other hand, when the first thermostat valve 72 is closed, the flow of the cooling water in the main cooling water path 62 is stopped, and the 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 for detecting the temperature of the cooling water flowing through the main cooling water path 62. The first water temperature sensor SN3 is located between the water pump 61 and the cylinder block 3, and more specifically, the cooling water flow direction indicated by the solid arrow in FIG. 2 is downstream of the water pump 61 and from the cylinder block 3. Is also provided at a position on the upstream side, and detects the temperature of the cooling water passing through this position. The second water temperature sensor SN4 is located downstream of the cylinder head 4 and upstream of the radiator 71 with respect to the position between the cylinder head 4 and the radiator 71, specifically, the cooling water flow direction indicated by the solid line arrow in FIG. It is provided at a position on the side, and detects the temperature of the cooling water passing through this position. Hereinafter, the temperature of the cooling water detected by the first water temperature sensor SN3 is appropriately referred to as an 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 set according to the engine water temperature. Open and close.

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

As shown by the one-point chain arrow in FIG. 2, a part of the cooling water flowing through the block-side water jacket 62a included in the main cooling water path 62 is introduced into the EGR cooling water path 63. The cooling water introduced from the block-side water jacket 62a into the EGR cooling water path 63 passes through the EGR cooler (EGR / C) 52, the air-conditioning heater core 74, and the exhaust port-side water jacket 63b formed in the cylinder head 4. Then, it 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 of the combustion chamber side water jacket 62b (downstream side in the flow direction of the exhaust gas). is there.

As described above, in the present embodiment, a part of the main cooling water path 62 including the block-side water jacket 62a and the EGR cooling water path 63 provide the water pump 61 and the water pump 61 in a path different from the main cooling water path 62. A path 160 for circulating cooling water is formed through 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 becomes the "cooling water path" of the claim. Equivalent to.

The position between the cylinder head 4 and the water pump 61 in the EGR cooling water path 63, specifically, the flow direction of the cooling water indicated by the one-point chain line arrow in FIG. 2 is downstream of the cylinder head 4 and the water pump 61. A flow control valve (S / V) 75 is interposed at a position on the upstream side of the flow control valve (S / V).

FIG. 4 is a schematic cross-sectional view of the flow control valve 75. FIG. 5 shows the opening degree of the flow control valve 75 (upper graph of FIG. 4) and the pressure of the cooling water in the EGR cooling water path 63, which is detected by the pressure sensor SN5 described later (FIG. 4). It is the figure which showed the lower graph). In the lower graph of FIG. 4, the change in the pressure of the cooling water is schematically shown.

The flow rate control valve 75 is a solenoid type on-off valve, and includes a valve main body 75a that opens and closes the EGR cooling water path 63, and a drive unit 75b that drives the valve main body 75a by receiving electric power. The flow control valve 75 is a normally open type, and when the power supply to the drive unit 75b is stopped, the valve body 75a is fully opened.

The drive unit 75b duty-drives the valve body 75a so that it opens and closes at a predetermined frequency. That is, the flow rate control valve 75 is a DUTY control valve, and as shown in FIG. 5, the valve body 75a is driven so as to repeat fully open and fully closed. Then, one energization is performed for a total period (one cycle) T of 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. By changing the period, that is, the duty ratio, which is the ratio of one valve closing period T2, the flow rate of the cooling water passing through the valve body 75a is changed. The electric power supplied to the drive unit 75b of the flow control valve 75 is controlled by the CSV control device 110 provided in the flow control valve 75 and the PCM 100 described later. The CSV control device 110 receives a command from the PCM 100, which will be described later, and supplies electric power to the drive unit 75b at the commanded cycle and the commanded duty ratio. Hereinafter, the ratio of the energization period, that is, the valve closing period T2 to the one cycle T of the flow control valve 75 is simply referred to as the duty ratio of the flow control valve 75.

As described above, since the flow control valve 75 is a normally open type, when the duty ratio of the flow control valve 75 is set to 0% and the power supply to the drive unit 75b is stopped, the valve body 75a of the flow control valve 75 Will be 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 drive unit 75b, the valve body 75a is kept fully closed.

Specifically, the drive unit 75b is in a direction in which the coil 171 that receives electric power to generate an electromagnetic force, the fixed core 172 that is magnetized by the electromagnetic force generated by the coil 171, and the fixed core 172 are brought into contact with each other. A movable core 173 that can be moved to, a drive pin 174 that is connected to the movable core 173 and moves integrally with the movable core 173, a retainer 175 that is attached to the tip of the drive pin 174, and a fixed core 172 and a retainer 175. It has a spring 176 to be magnetized. 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 above FIG. 4 so as to urge the retainer 175 in the direction in which the valve body 75a opens. When power is supplied to the coil 171, the movable core 173 is sucked into 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 retainer 175 and the valve body 75a move upward in FIG. 4 due to the urging force of the spring 176, and the valve body 75a is fully opened.

The EGR cooling water path 63 is provided with a pressure sensor SN5 that detects the pressure of the cooling water flowing through the path 63. The pressure sensor SN5 is located between the cylinder head 4 and the flow control valve 75, specifically, the flow direction of the cooling water indicated by the one-point chain arrow in FIG. 2 is downstream of the cylinder head 4 and the flow control valve 75. It is provided at a position on the upstream side, and detects the pressure of the cooling water passing through this position.

The EGR cooling water path 63 is connected to the main cooling water path 62 via a connecting 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 connecting 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 the connecting path 65.

The valve path 66 is a path connecting the combustion chamber side water jacket 62b and the 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 62b joins the EGR cooling water path 63 through the valve path 66 and 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 a part of the main cooling water path 62 separately from the EGR cooling water path 63, and connects the block side water jacket 62a and the water pump 61. As shown by the broken line arrow in FIG. 2, a part of the cooling water in the block-side water jacket 62a is diverted from the main cooling water path 62, and the ATF warmer (ATF / W) 76 and the oil cooler (O / C) are separated. After passing through 77, it returns to the water pump 61. The ATF warmer 76 is a device for heating an ATF (automatic transmission fluid), that is, a liquid used in a transmission, and an oil cooler 77 is a device for cooling a lubricating oil supplied to an engine body 1 or the like.

Of the ATF cooling water path 64, a second thermostat valve (T / S) that opens and closes this portion is located between the ATF warmer 76 and the connection portion between the main cooling water path 62 (block side water jacket 62a). ) 78 is installed. The second thermostat valve 78 is a thermostat valve having a fixed valve opening temperature.

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

Detection signals from various sensors are input to the PCM100. For example, the PCM 100 is electrically connected to the crank angle sensor SN1, the airflow sensor SN2, the first water temperature sensor SN3, the second water temperature sensor SN4, and the pressure sensor SN5 described above. 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. Further, the vehicle is provided with an accelerator pedal sensor SN6 that detects the opening degree of the accelerator pedal operated by the driver who drives the vehicle, and the detection signal by the accelerator pedal sensor SN6 is also sequentially input to the PCM 100.

The PCM 100 controls each part of the engine while executing various determinations and calculations based on the input information from each sensor. The PCM100 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 control device 110 (flow control valve 75). ) Etc. are electrically connected to each other, and a control signal is output to each of these devices based on the result of the above calculation or 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. The PCM 100 corresponds to the "control means" of the claim.

The combustion control unit 101 is a control module that controls the 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 has failed.

(3-1) Normal control (combustion control unit)
The combustion control unit 101 performs the following control in the normal state 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 opening degree 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.

The combustion control unit 101 compares the calculated required output with the engine output guard value, and sets a smaller value among these as the target output. Next, the combustion control unit 101 calculates the amount of air and the amount of fuel to be introduced into the combustion chamber 6 in order to realize this target output. Then, the combustion control unit 101 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 that is sufficiently larger than the maximum value of the required output, that is, the required output when the accelerator pedal is fully opened. From this, in the normal time when it is not determined that the flow control valve 75 is out of order, the target output is set to the required output, and the throttle valve 32 and the injector 15 are driven so that the required output is realized.

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

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

The cooling water control unit 102 determines the valve 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 valve opening temperature of the first thermostat valve 72 between the first temperature and the second temperature 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 lower 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, and the thermostat heater 72b The amount of electricity supplied to the thermostat heater 72b is adjusted so that the temperature becomes a temperature corresponding to this. 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 electricity supplied to the thermostat heater 72b is adjusted so that the temperature becomes the same. As a result, when the engine water temperature is lower 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, and the engine body 1 is prohibited from being supplied. Warm-up of 1 is promoted. 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 supply of the cooling water cooled by the radiator 71 to the engine body 1 is started, and the engine by the cooling water is started. 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 lower than the first temperature but higher than the second temperature. 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 about 90 ° C. and the second temperature is set to about 80 ° C. Further, the reference wall temperature is a temperature at which SPCCI combustion is appropriately realized, and is set to the wall temperature of the combustion chamber 6 when the engine water temperature reaches about 120 ° C., for example, 116 ° C.

An estimated value is used for the wall temperature of the combustion chamber 6, which is 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 temperature of the cooling water 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 lower than the first temperature and the warm-up of the engine body 1 is not completed, the cooling water control unit 102 prohibits the opening of the flow rate control valve 75 and sets the 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, the flow control valve 75 is allowed to open and close. 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 the present 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 and lengthens the valve opening period T1 of the flow control valve 75. To do. When the valve opening period T1 of the flow rate control valve 75 becomes long, 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 rate 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 blocks by increasing the duty ratio of the flow control valve 75 and shortening the valve opening period T1 of the flow control valve 75. The cooling water flowing through the side water jacket 62a and the exhaust port side water jacket 63b is reduced. 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 water temperature becomes equal to or higher than a predetermined temperature regardless of the operating state of the engine. The valve opening temperature of the second thermostat valve 78 is set to a temperature lower than the first temperature, for example, 50 ° C.

According to the above configuration, when the engine is started in a state where the engine water temperature is lower than the valve opening temperature of the second thermostat valve 78, that is, when the engine is cold started, the first and second engines are immediately after the start. The thermostat valve 78 and the flow control valve 75 are all maintained in the closed state. As a result, the engine body 1 is not cooled by the cooling water, and the engine body 1 is warmed up. When the engine body 1 is warmed up and the engine water temperature becomes equal to or higher than the valve opening temperature of the second thermostat valve 78, the second thermostat valve 78 is opened. As a result, the cooling water flows through the cooling water path 64 for ATF, 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 cooling water further rises to the first temperature or higher, that is, when the warm-up of the engine body 1 is completed, 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 main body 1 by the cooled cooling water is started. Further, when the cooling water reaches the first temperature or higher, the flow control valve 75 is allowed to open, and the flow control valve 75 is opened and closed so that the wall temperature of the combustion chamber 6 becomes the target wall temperature.

(Failure judgment unit)
The procedure for determining the failure of the flow control valve 75, which is carried out 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 the value 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 rate control valve 75 from the valve open state to the valve closed state, specifically, the flow rate control valve 75. On the other hand, it is determined whether or not the state in which the command to stop energization has been issued has been switched to the state in which the command to energize has been issued. The failure determination unit 103 makes this determination based on the 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 as it is (returns to step S1). On the other hand, if this determination is YES and a valve closing command is 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 the determination amount to be used in step S4 described later. To do. When the flow control valve 75 is closed, the cooling water is blocked 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, the piping, or the like due to its inertia, and a so-called water hammer phenomenon occurs. From this, 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 rises sharply from P1 to P2. In step S3, the amount of increase in this pressure is calculated. Specifically, from the pressure detected by the pressure sensor SN5 at the timing when the valve closing command is issued to the flow control valve 75 (the timing when the command is issued to energize the flow control valve 75). , The pressure detected by the pressure sensor SN5 was subtracted at the timing immediately before the valve closing command was issued to the flow control valve 75 (the timing immediately before the command was issued to start energizing the flow control valve 75). The value is calculated as the amount of increase in pressure. 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 the preset determination threshold value. The determination threshold value is preset to a value larger 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 as it is (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 value, 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 is stopped. 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 larger than the preset number of abnormality determinations. If the determination in step S6 is YES and the abnormality counter is larger than the number of abnormality determinations, the failure determination unit 103 proceeds to step S7 and determines that the flow control valve 75 is abnormal, that is, it has failed. .. On the other hand, if the determination in step S6 is NO and the abnormality counter is less than or equal to the number of abnormality determinations, the failure determination unit 103 ends the process as it is (returns to step S1). The number of times of abnormality determination is set in advance to a value larger than 0 and stored in the failure determination unit 103.

As described above, in the present embodiment, whether or not the flow rate control valve 75 is abnormal (whether or not it is out of order) is determined based on the pressure change in the EGR cooling water path 63 that occurs when the flow rate control valve 75 is opened and closed. When the determination is made and the abnormality counter becomes larger than the number of times of abnormality determination, a failure of the flow control valve 75 is detected. That is, as described above, if the flow control valve 75 opens and closes normally, the water hammer phenomenon occurs and the pressure of the cooling water rises, but when the flow control valve 75 does not open and close normally, the pressure of the cooling water Is almost unchanged. From this, in the present embodiment, when the determination amount is equal to or less than the determination threshold value, it is highly likely that the flow control valve 75 is not opened and closed normally, and the number of times the determination amount is equal to or less than the determination threshold value is predetermined. If the number of times is exceeded, it is judged to be abnormal.

(3-2) Control at the time of failure of the flow control valve Next, the control of the combustion control unit 101 and the cooling water control unit 102 when the flow control valve 75 is determined to be failed by the failure determination unit 103 is shown in FIG. 8 and the flowchart of FIG. 9 will be described.

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

If the determination in step S11 is NO and the flow control valve 75 is not determined to be abnormal, the process proceeds to step S12. In step S12, the cooling water control unit 102 executes the above-mentioned normal control for the flow rate control valve 75. That is, when the engine water temperature is lower than the first temperature, the flow control valve 75 is kept fully closed, and when the engine water temperature is higher than the first temperature, the flow control valve is set so that the wall temperature of the combustion chamber 6 becomes the target wall temperature. Control 75.

On the other hand, if the determination in step S11 is YES and the flow control valve 75 is determined to be abnormal, the process proceeds to step S13. In step S13, the cooling water control unit 102 continuously stops the energization of the flow rate control valve 75 for a predetermined period. The energization of the flow control valve 75 is stopped for a period longer than at least one cycle T described above. When the energization of the flow control valve 75 is stopped, the valve body 75a is urged to the valve opening side by the spring 176. 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 engine water temperature after stopping the energization of the flow control valve 75 is larger than the amount of decrease in determination. The determination reduction amount is preset to a value larger 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 engine water temperature after stopping the energization of the flow control valve 75 is larger than the amount of decrease in determination, the process proceeds to step S15.

In step S15, the cooling water control unit 102 releases the power stoppage of the flow control valve 75, and returns the control thereof to the normal control.

The valve body 75a of the flow control valve 75 is fixed in the closed side (fully closed state or an intermediate state between fully closed and fully open), and as a result, it is determined that the flow control valve 75 is abnormal. In this case, the sticking of the valve body 75a may be released by stopping the energization of the flow control valve 75. Specifically, when the energization of the flow control valve 75 is stopped, the urging force of the spring 176 is applied to the valve body 75a of the flow control valve 75. As a result, the valve body 75a tends to move vigorously to the valve opening side, so that the valve body 75a may be released from sticking. When the sticking of the valve body 75a on the closed side is released and the valve body 75a is fully opened, the flow rate of the cooling water passing through the flow control valve 75 and the flow rate of the cooling water flowing through 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 decreases.

Further, 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 the foreign matter X1 and X2 are caught between the valve body 75a and the inner wall of the passage. As a result, if the valve body 75a does not open and close properly, and if it is determined that the flow control valve 75 is abnormal, the energization of the flow control valve 75 is stopped 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. In this case as well, the flow rate of the cooling water increases with the removal of the foreign matter, and the temperature of the cooling water decreases.

From this, when the amount of decrease in engine water temperature after stopping the energization of the flow rate control valve 75 becomes larger than the amount of decrease in judgment, the flow control valve 75 is released from sticking or foreign matter is removed. It is thought that it was. Therefore, in the present embodiment, if the determination in step S14 is YES, it is presumed that the flow control valve 75 can be opened and closed appropriately, and the control of the flow control valve 75 is changed to the normal control in step S15. return.

On the other hand, if the amount of decrease in the engine water temperature after the power flow control valve 75 is stopped is equal to or less than the amount of the determination decrease, it is presumed that the above-mentioned sticking was not released or the foreign matter was not removed. From this, if the determination in step S15 is NO, the process proceeds to step S16, and failure control is performed.

FIG. 9 is a flowchart showing the procedure of control at the time of failure.

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 the present embodiment, the 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 the third temperature or higher. After step S21, the process proceeds to step S22.

The third temperature is preset and stored in the cooling water control unit 102. In the present 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, and the valve opening temperature is changed to the third temperature. Along with this, the first thermostat valve 72 is opened. The third temperature may be set to a temperature higher than this lower limit (however, a temperature lower than the first temperature) or a second temperature. When the first thermostat valve 72 is opened, 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 target temperature at the time of failure is cooling water that can suppress the temperature of the engine body 1 to a predetermined temperature or lower (for example, a temperature at which so-called overheating does not occur) even when the flow control valve 75 is fixed in the closed state. The temperature is set slightly lower than the upper limit of the temperature.

If the determination in step S22 is NO and the engine water 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 the present 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. Similar to the normal case, when the flow rate control valve 75 fails, the combustion control unit 101 compares the required output with the engine output guard value, and sets the smaller value among them as the target output. From this, when the engine output guard value is set to the second guard value, the target output is set to the required output, that is, the second guard value smaller than the normal target output even if the accelerator pedal is fully opened. .. Then, the combustion control unit 101 drives the throttle valve 32 and the injector 15 so as to realize this target output, whereby the engine output is reduced from the normal engine output.

On the other hand, if the determination in step S22 is YES and the engine water 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 releases the restriction on the engine output and ends the process (returns to step S1). Specifically, the combustion control unit 101 returns the engine output guard value to the first guard value. During the failure control, the power supply to the flow control valve 75 is continuously stopped.

(4) Action, etc. As described above, in the present embodiment, when it is determined that the flow control valve 75 is out of order, the energization of the flow control valve 75 is stopped and 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 rate control valve 75 and remove the foreign matter adhering to the periphery of the flow rate control valve 75 with a large amount of cooling water. Further, when the flow control valve 75 moves vigorously to the fully open side, it becomes possible to release the sticking of the flow control valve 75. Therefore, the flow control valve 75 can be returned to normal. Further, even when the flow rate control valve 75 does not open and close properly, it is possible to avoid a further decrease in the flow rate of the cooling water that passes through the flow rate control valve 75 and circulates in the engine body 1. Therefore, it is possible to prevent the engine body 1 from being overheated. Since the overheating of the engine body 1 can be prevented by controlling the flow control valve 75 in this way, the opportunity to limit the engine output in order to prevent the overheating can be reduced, and the engine output can be increased. It becomes possible to secure.

In particular, in the present embodiment, the flow rate control valve 75 is a normally open type, and the valve 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.

Further, in the present embodiment, when it is determined that the flow control valve 75 is out of order, the engine output is limited, so that the overheating of the engine body 1 can be prevented more reliably. .. Here, as described above, in the present embodiment, the chance of limiting the engine output can be reduced. Therefore, it is possible to prevent the engine output from being significantly reduced while more reliably preventing the engine body 1 from being overheated.

Further, in the present embodiment, when it is determined that the flow control valve 75 is out of order, the valve opening temperature of the first thermostat valve 72 is reduced to open the first thermostat valve 72. Therefore, the cooling water can be reliably introduced into the radiator 71 to be cooled, and the engine body 1 can be sufficiently cooled by the cooling water, and the engine body 1 can be prevented from being overheated more reliably.

Here, since the engine water temperature can be lowered by reducing the valve opening temperature of the first thermostat valve 72, the engine body 1 is overloaded even if the engine output limit is released when the engine water temperature falls below the failure target temperature. It is possible to prevent the temperature rise. On the other hand, as described above, in the present embodiment, the output restriction of the engine is released when the engine water temperature becomes equal to or lower than the failure target temperature. Therefore, a high engine output can be realized while preventing an excessive temperature rise of the engine body 1.

Further, in the present embodiment, whether or not the flow rate control valve 75 is out of order is determined based on the pressure change at the time of opening and closing of the flow rate control valve 75 generated in the EGR cooling water path 63 in which the flow rate control valve 75 is arranged. Judging. As shown in FIG. 5, the pressure of the cooling water is sensitively changed as the flow control valve 75 opens and closes. Therefore, by configuring the flow control valve 75 to determine whether or not it has failed based on the pressure change of the cooling water, this determination can be performed early and accurately.

Further, in the present 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 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 set to a temperature suitable for combustion. In particular, in SPCCI combustion, it is necessary to compress and ignite a part of the air-fuel mixture, and it is required to accurately control the wall temperature of the combustion chamber 6. On the other hand, 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 realized.

(5) Modification Example 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 opening of the accelerator pedal 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.

Further, in the above embodiment, the control of limiting the engine output when the flow control valve 75 fails and the control of lowering the opening temperature of the first thermostat valve 72 when the flow control valve 75 fails may be omitted. .. Further, it may be configured to carry out only one of these controls.

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

Specific numerical values such as the first temperature and the second temperature shown in the above embodiment are merely examples. These temperatures can be appropriately changed according to the specific configuration 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 be applied to an engine in which the combustion mode in the entire operating region is controlled to be 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 (thermostat valve valve body)
72b Thermostat heater 72b (valve opening temperature change part)
72 1st thermostat valve (thermostat valve)
75 Flow control valve 100 PCM (control means)
160 Cooling water path (1st cooling water path)
SN5 pressure sensor

Claims (6)

It ’s an engine cooling device.
A cooling water path that circulates cooling water via the engine body,
A flow control valve that can open and close the cooling water path,
A control means for controlling the flow rate control valve is provided.
The control means determines whether or not the flow control valve is out of order, and when it is determined that the flow rate control valve is out of order, the flow rate control valve is continuously fully opened for at least a predetermined period of time. An engine cooling device characterized in that the flow control valve is controlled. The engine cooling device according to claim 1.
The flow control valve is configured to open and close in response to the supply of electric power and to be fully opened when the supply of the electric power is stopped.
The control means is an engine cooling device, characterized in that, when it is determined that the flow control valve is out of order, the power supply to the flow control valve is stopped. The engine cooling device according to claim 1 or 2.
The control means is an engine cooling device, which limits the output of the engine 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.
With a radiator that cools the cooling water,
A path for circulating cooling water via the engine body, and a radiator-side cooling water path for diversion of cooling water from the cooling water path and passing through the radiator.
A valve body arranged in the middle of the radiator side cooling water path, and the valve 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 is opened. A thermostat including a valve body that closes when the valve temperature is lower than the valve temperature and a valve opening temperature changing portion that can change the valve opening temperature is further provided.
The control means is an engine cooling device that controls the valve opening temperature changing unit so that the valve opening temperature of the thermostat drops when it is determined that the flow rate control valve is out of order. The engine cooling device according to any one of claims 1 to 4.
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.
The engine cooling device is characterized in that the control means determines whether or not the flow control valve has failed based on a value detected by the pressure sensor when the flow control valve is opened and closed. In the engine cooling device according to any one of claims 1 to 5.
The control means is an engine cooling device, characterized in that the flow control valve is opened and closed so that the wall temperature of a combustion chamber formed in the engine body becomes a preset target temperature.