JP2016065517A - Cooling system of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of output performance in evacuation running, while preventing overheat of an engine, in a failure of a flow rate control valve for controlling flow of cooling water.SOLUTION: A cooling system of an engine includes: a cooling water flow passage through which cooling water circulates, the cooling water flow passage containing a flow passage passing through the engine; a cooling water pump that circulates cooling water in the cooling water flow passage; a flow rate control valve that controls a flow rate of cooling water flowing in the cooling water flow passage; valve control means that controls opening of a flow rate control valve; fault state detection means that detects a fault of the flow rate control valve; and output restriction means that when a fault is detected by the fault detection means, sets an output restriction value of the engine and restricts output of the engine so as to become an output restriction value or less. The output restriction means sets the output restriction value to a larger value as a flow rate of cooling water flowing in the engine is larger.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an engine cooling system.

  Conventionally, an in-block path that guides cooling water to the cylinder head via the cylinder block, a block bypass path that bypasses the intra-block path and guides cooling water to the cylinder head, and a branch point between the in-block path and the block bypass path There is known an engine cooling device having a thermostat valve that is arranged in a circuit and switches a path for flowing cooling water (Patent Document 1).

  In this cooling device, during the warming up of the engine, the cooling water is supplied to the block bypass path to promote the warming up of the cylinder block. The thermostat valve is controlled to prevent the rise.

  The cooling device is provided between the cylinder block and the cylinder head and opens when a predetermined temperature is reached, and detects the temperature of cooling water flowing from the cylinder block to the cylinder head via the temperature sensing valve. A temperature sensor that performs the failure determination of the thermostat valve based on the detection result of the temperature sensor.

  According to this configuration, the temperature sensing valve opens when the temperature of the temperature sensing valve rises to a predetermined temperature due to the failure of the thermostat valve to prevent the cooling water from flowing into the path in the block. When the temperature sensing valve opens, the accumulated cooling water whose temperature rises in the cylinder block flows to the cylinder head through the temperature sensing valve, and the temperature is measured. From the measurement result, it is determined that the thermostat valve has failed. Is done. If it is determined that the thermostat valve has failed, engine output is limited to prevent engine burn-in.

JP 2009-197664 A

  By the way, in the event of a failure of a valve that controls the flow of cooling water, it is necessary to travel the vehicle to a safe place or a car dealer (so-called retreat travel). On the other hand, when the vehicle speed rapidly decreases against the driver's intention during the evacuation travel, the driver may not only feel uncomfortable but also the safety may decrease. For this reason, at the time of the above-mentioned failure, it is desirable to prevent the output performance during the retreat travel from being reduced as much as possible while preventing the engine from overheating.

  However, Patent Document 1 does not show anything about suppressing a decrease in output performance during retreat travel.

  The present invention has been made in view of the above circumstances, and suppresses a decrease in output performance during retreat travel while preventing engine overheating when a flow control valve that controls the flow of cooling water fails. An object of the present invention is to provide an engine cooling system.

  In order to solve the above-described problems, the present invention includes a cooling water passage that includes a passage that passes through an engine and in which cooling water circulates, a cooling water pump that circulates cooling water in the cooling water passage, A flow rate control valve for controlling a flow rate of cooling water flowing through the cooling water flow path, a valve control means for controlling an opening degree of the flow rate control valve, a failure state detecting means for detecting a failure of the flow rate control valve, and the failure detection Output limit means for setting an output limit value of the engine and limiting the output of the engine to the output limit value or less when a failure is detected by the means, and the output limit means includes the output limit value Is set to a larger value as the flow rate of the cooling water flowing through the engine is larger, and the engine cooling system is provided.

  According to the present invention, the output control means sets the engine output limit value and limits the engine output to the output limit value or less when a failure is detected by the failure detection means. Further, the output limiting means sets the output limit value to a larger value as the flow rate of the cooling water flowing through the engine increases. When the flow rate of the cooling water flowing through the engine is large, overheating of the engine can be prevented without limiting the engine output to a small value. Therefore, according to the present invention, when the flow control valve breaks down, it is possible to perform retreat travel without preventing engine output performance from being unnecessarily reduced while preventing engine overheating.

  The present invention further includes temperature detection means for detecting the temperature of the cooling water flowing through the engine, and the output restriction means increases the output restriction value as the temperature detected by the temperature detection means is lower. It is preferable to set the value.

  According to this configuration, the lower the temperature detected by the temperature detecting means, the larger the engine output limit value is set. When the temperature of the cooling water flowing through the engine is low, there is room for temperature and time before the engine is overheated. Therefore, according to this configuration, the effect of performing retreat travel without reducing the output performance of the engine more than necessary can be achieved more reliably.

  In the present invention, it is preferable that the output limiting unit sets the output limiting value to a predetermined maximum value when the temperature detected by the temperature detecting unit is lower than a predetermined temperature. .

  According to this configuration, when the temperature detected by the temperature detecting means is lower than a predetermined temperature, the engine output limit value is set to a predetermined maximum value, so that the output reduction during the retreat travel is sufficiently reduced. Can be suppressed.

  In the present invention, it is preferable that the output limiting means sets the output limiting value to a larger value as the engine speed is lower.

  According to this configuration, the engine output limit value is set to a larger value as the engine speed is lower. The lower the engine speed, the smaller the engine heat generation per unit time. Therefore, the effect of performing retreat travel without degrading the output performance of the engine more than necessary can be achieved more reliably.

  In the present invention, the flow control valve is a rotary valve having a predetermined correlation between an opening degree and a rotation angle, and the cooling system detects a rotation angle of the flow control valve. The failure state detection means further includes a detection rotation angle detected by the rotation angle detection means, and a control value of the rotation angle output from the valve control means to the flow rate control valve. It is preferable to detect a failure of the flow control valve based on a difference from the control rotation angle.

  According to this configuration, the failure of the flow rate control valve is detected based on the difference between the detected rotation angle detected by the rotation angle detection means and the control rotation angle output from the valve control means. If the difference between the detected rotation angle and the control rotation angle is large, it is considered that the flow control valve has failed. Therefore, the failure of the flow control valve can be detected effectively.

  In the present invention, the cooling water flow path includes a radiator flow path that passes through a radiator, and the output control means is configured to control the flow rate control when the flow control valve is open with respect to the radiator flow path. It is preferable to set the output limit value to a larger value than when the valve is not opened with respect to the radiator passage.

  According to this configuration, when the cooling water flows through the radiator, the engine output limit value is set to a larger value than when the cooling water does not flow through the radiator. When the cooling water flows through the radiator, the cooling water is cooled by the radiator, so that the engine can be effectively cooled. Therefore, by changing the engine output limit value depending on whether or not the cooling water flows to the radiator, the effect of performing retreat travel without degrading the output performance of the engine more than necessary can be achieved more reliably. Can do.

  In the present invention, the cooling water flow path includes a radiator flow path that passes through a radiator, and the output limiting means is preset for each opening level of the flow rate control valve with respect to the radiator flow path, and When storing a plurality of engine output restriction patterns that define the relationship between the temperature of cooling water flowing through the engine and the limit value of the fuel injection amount to the engine, and when a failure is detected by the failure detection means, Preferably, one engine output restriction pattern corresponding to the opening level of the flow control valve is selected from the plurality of engine output restriction patterns, and the fuel injection amount is restricted based on the selected engine output restriction pattern.

  According to this configuration, the output limiting means is preset for each opening level of the flow rate control valve with respect to the radiator passage, and the relationship between the temperature of the cooling water flowing through the engine and the limit value of the fuel injection amount to the engine. A plurality of prescribed engine output restriction patterns are stored. When a failure of the flow control valve is detected, an engine output restriction pattern corresponding to the opening degree of the flow control valve is selected from the plurality of engine output restriction patterns, and the fuel injection amount is restricted. If the water flow to the radiator is different, the cooling capacity of the engine is also different. Therefore, by changing the output restriction pattern in accordance with the amount of water flow to the radiator, it is possible to finely restrict the engine output during retreat travel.

  In the present invention, the plurality of engine output restriction patterns are set such that the limit value of the fuel injection amount at the same cooling water temperature is set higher as the opening level of the flow control valve with respect to the radiator passage is higher. Preferably it is.

  The more the flow rate of the coolant flowing through the radiator passage (the greater the opening degree of the flow control valve), the higher the cooling capacity of the engine. Therefore, when the opening level of the flow rate control valve with respect to the flow path through the radiator is higher in the plurality of engine output restriction patterns, the limit value of the fuel injection amount at the same cooling water temperature is set higher. It is possible to appropriately limit the output so as not to reduce the engine output as much as possible within a safe range.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the output performance at the time of evacuation driving | running | working can be suppressed, preventing engine overheating at the time of the failure of the flow control valve which controls the flow of cooling water.

It is a figure which shows the engine and intake / exhaust system in embodiment of this invention. It is a figure which shows PCM, the input device, and the output device in embodiment of this invention. It is a flowchart which shows control of the intake-exhaust system of the engine in embodiment of this invention. It is a block diagram which shows the cooling system of the engine in embodiment of this invention. It is a graph which shows the relationship between the rotation angle and opening degree (communication area) of the flow control valve in embodiment of this invention. It is a flowchart which shows the water flow switching operation | movement of the cooling water flow path in embodiment of this invention. It is a flowchart which shows the step-wise valve opening control of the flow control valve in embodiment of this invention. It is a graph which shows the timing of the opening degree increase of the flow control valve in the embodiment of the present invention. It is a graph which shows the temperature change (upper stage) of the cooling water in embodiment of this invention, and the change (lower stage) of the sum of the opening degree of the flow control valve with respect to each flow path. It is a figure which shows the output limitation pattern of the engine in embodiment of this invention, (a) is a figure when an engine speed is 1600 rpm, (b) is a figure when an engine speed is 4500 rpm. It is a flowchart which shows the failure determination operation | movement of the flow control valve in embodiment of this invention. It is a flowchart which shows the output limitation operation | movement of the engine in embodiment of this invention.

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

  First, the engine 9 and its intake / exhaust system according to an embodiment of the present invention will be described.

  The engine 9 is a diesel engine for driving a vehicle.

  The engine 9 includes a cylinder block 9a provided with a plurality of cylinders (only one is shown in FIG. 1), a cylinder head 9b provided on the upper side of the cylinder block 9a, and a lower side of the cylinder block 9a. Oil pan 9c.

  In each cylinder, a piston 9f connected to a crankshaft 9e via a connecting rod 9d is removably fitted.

  An intake port 9g and an exhaust port 9h are formed in each cylinder in the cylinder head 9b. An intake valve 9j and an exhaust valve 9k are provided in the intake port 9g and the exhaust port 9h, respectively.

  The cylinder head 9b is provided with an electromagnetic direct injection injector 9m that injects fuel into each cylinder. The direct injection injector 9m is supplied with fuel from a fuel tank via a fuel pump and a common rail (both not shown). The common rail is provided with a fuel pressure sensor 36 (see FIG. 2) for detecting the fuel pressure.

  The intake / exhaust system of the engine 9 includes an intake passage 20 that guides intake air into the cylinder through an intake port 9g, and an exhaust passage 21 that exhausts exhaust gas generated in the cylinder into the atmosphere.

  In the intake passage 20, an air cleaner 22 that removes dust and dirt contained in the intake air, a turbocharger compressor 24, an intake shutter valve 11 b that shuts off the intake passage 20, and an intake shutter valve 11 b are driven in order from the upstream side. An intake shutter valve actuator 38, an intercooler 25 that forcibly cools intake air that has been compressed by the compressor 24 to high pressure and high temperature, an intercooler cooling water pump 26 that sends cooling water to the intercooler 25, and the like are provided.

  The exhaust passage 21 is provided with an exhaust turbine 27 of a turbocharger, a diesel oxidation catalyst (DOC) 28, a DPF (Diesel Particulate Filter) 29 for collecting exhaust particulates in the exhaust gas, and the like in order from the upstream side.

  The intake / exhaust system includes a high pressure EGR (Exhaust Gas Recirculation) device 30 and a low pressure EGR device 31.

  The high pressure EGR device 30 adjusts the flow rate of the high pressure EGR gas in the high pressure EGR passage 30a and the high pressure EGR passage 30a connecting the upstream side of the intake port 9g in the intake passage 20 and the downstream side of the exhaust port 9h in the exhaust passage 21. A high pressure EGR valve 11a and a high pressure EGR valve actuator 30b for driving the high pressure EGR valve 11a are provided.

  The low pressure EGR device 31 includes a low pressure EGR passage 31a that connects the downstream side of the DPF 29 in the exhaust passage 21 and the upstream side of the compressor 24 in the intake passage 20, and a low pressure EGR valve that adjusts the flow rate of the low pressure EGR gas in the low pressure EGR passage 31a. 11d, a low pressure EGR valve actuator 31b that drives the low pressure EGR valve 11d, and a low pressure EGR cooler 11c that cools the low pressure EGR gas.

  The engine 9 and the intake / exhaust system configured as described above are controlled by a PCM (Powertrain Control Module) 8. The PCM 8 includes a CPU, a memory, an interface, and the like.

  As shown in FIG. 2, detection signals from various sensors are input to the PCM 8. The various sensors include an intake port temperature sensor 33 that is attached to the intake port 9g and detects the temperature of intake air immediately before flowing into the cylinder, and a water temperature sensor that detects the temperature of engine cooling water in the vicinity of the intake port 9g. 7, a crank angle sensor 34 for detecting the rotation angle of the crankshaft 9e, an accelerator opening sensor 35 for detecting an accelerator opening corresponding to an operation amount of an accelerator pedal (not shown) of the vehicle, and a direct injection injector 9m A fuel pressure sensor 36 for detecting the fuel pressure to be supplied, an oxygen concentration sensor 32 for detecting the oxygen concentration in the exhaust gas on the downstream side of the DPF 29, and the like are included.

  The PCM 8 performs various calculations based on the detection signals of the sensors to determine the state of the engine 9, the intake / exhaust system, and the like, and according to this, the direct injection injector 9m and various valve actuators (intake shutter valve actuators) 38, control signals are output to the high pressure EGR valve actuator 30b and the low pressure EGR valve actuator 31b) (engine control function and intake / exhaust system control function).

  Next, the control performed by the PCM 8 will be described with reference to the flowchart of FIG.

  First, the PCM 8 reads detection values of various sensors (step S31).

  Next, the PCM 8 calculates the engine speed based on the rotation angle detected by the crank angle sensor 34, and sets the target torque based on the engine speed and the accelerator opening detected by the accelerator opening sensor 35. (Step S32).

  Next, the PCM 8 sets the required fuel injection amount based on the engine speed and the target torque (step S33).

  Next, the PCM 8 selects a fuel injection pattern corresponding to the required injection amount and the engine speed from the plurality of fuel injection patterns stored in advance in the memory (step S34).

  Next, the PCM 8 sets the pressure (fuel pressure) of the fuel supplied to the direct injection injector 9m based on the required injection amount and the engine speed (step S35).

  Next, the PCM 8 sets a target oxygen concentration based on the required injection amount and the engine speed (step S36). The target oxygen concentration is a target value of the oxygen concentration of the mixed air immediately before flowing into the cylinder.

  Next, the PCM 8 sets a target intake air temperature based on the required injection amount and the engine speed (step S37). The target intake air temperature is a target value of the temperature of the mixed air immediately before flowing into the cylinder.

  Next, the PCM 8 selects an EGR control mode corresponding to the required injection amount and the engine speed from a plurality of EGR control modes stored in advance in the memory (step S38). The EGR control mode is selected for each of the high pressure EGR device 30 and the low pressure EGR device 31.

  Next, the PCM 8 sets state quantities (high pressure EGR quantity, low pressure EGR quantity, and supercharging pressure) that realize the target oxygen concentration and the target intake air temperature (step S39).

  Next, the PCM 8 reads the limit range of each state quantity from the memory (step S40). The limit range is a range that each state quantity should satisfy in order for the engine 9 and the intake / exhaust system to operate properly, and is stored in advance in the memory.

  Next, the PCM 8 determines whether or not the state quantity set in step S39 is within the limit range (step S41).

  If it is determined that the state quantity is within the limit range (YES in step S41), the process proceeds to step S43. In step S43, the PCM 8 sets control amounts for the direct injection injector 9m, the intake shutter valve actuator 38, the high pressure EGR valve actuator 30b, and the low pressure EGR valve actuator 31b based on the state quantities set in step S39.

  Next, the PCM 8 controls the direct injection injector 9m, the intake shutter valve actuator 38, the high pressure EGR valve actuator 30b, and the low pressure EGR valve actuator 31b based on the set control amount (step S44).

  If it is determined in step S41 that there is a state quantity that is not within the limit range, the PCM 8 corrects the state quantity to be within the limit range (step S42). For example, the state quantity is corrected to the limit value closest to the state quantity set in step S39 within the limit range. After step S42, the PCM 8 controls the direct injection injector 9m, the intake shutter valve actuator 38, the high pressure EGR valve actuator 30b, and the low pressure EGR valve actuator 31b based on the corrected state quantity (step S44).

  Next, a cooling system for the engine 9 according to the embodiment of the present invention will be described.

  As shown in FIG. 4, the cooling system 1 of the engine 9 includes a cooling water flow path including a first flow path 2, a second flow path 3, and a third flow path 4, a cooling water pump 5, and a flow rate control valve. 6, a water temperature sensor 7, and a PCM 8. Cooling water circulates in the cooling water flow path.

  The first flow path 2 is a cooling water flow path that passes through the cylinder head 9 b of the engine 9. The first flow path 2 has a branch point P1 where the second flow path 3 branches on the downstream side of the cylinder head 9b. The first flow path 2 has a first auxiliary flow path 2a (path (1)) on the downstream side of the branch point P1. The first auxiliary flow path 2a passes through the high pressure EGR valve 11a and the intake shutter valve 11b.

  The second flow path 3 is a cooling water flow path that passes through the auxiliary machine 11 of the engine 9. The second flow path 3 has a branch point P2 on the downstream side of the branch point P1. The second flow path 3 has a second auxiliary flow path 3a (path (2)) and a third auxiliary flow path 3b (path (4)) connected to the branch point P2. The second auxiliary machine flow path 3a and the third auxiliary machine flow path 3b are connected in parallel to each other at the branch point P2.

  The second auxiliary flow path 3a passes through the low pressure EGR valve 11d, the low pressure EGR cooler 11c, and the heater core 11e.

  The third auxiliary flow path 3b passes through the radiator 11f.

  The third flow path 4 (path (3)) passes through a cylinder block 9a of the engine 9, an oil cooler 11g, and an ATF (Automatic Transmission Fluid) cooler 11h.

  The coolant pump 5 is a turbo pump and has a structure in which an impeller is indirectly connected to a crankshaft 9 e of the engine 9. The input port 5a of the cooling water pump 5 is connected to the downstream end of the first auxiliary flow path 2a, the downstream end of the second auxiliary flow path 3a, and the third auxiliary flow path 3b via the flow rate control valve 6. And the downstream end of the third flow path 4. The output port 5 b of the cooling water pump 5 is connected to the upstream end of the first flow path 2 and the upstream end of the third flow path 4.

  The cooling water pump 5 supplies the cooling water in the first auxiliary flow path 2a, the second auxiliary flow path 3a, the third auxiliary flow path 3b, and the third flow path 4 through the input port 5a. Further, the suction is performed by the pump action accompanying the rotation operation of the impeller using a part of the engine torque, and is discharged to the first flow path 2 and the third flow path 4 through the output port 5b. The cooling water sucked into the cooling water pump 5 is agitated in the cooling water pump 5 and then discharged.

  The flow control valve 6 is a single rotary valve. The flow control valve 6 includes a cylindrical casing, a cylindrical valve body rotatably accommodated in the casing, and an actuator that rotationally drives the valve body in one direction. The actuator rotationally drives the valve body in accordance with (drive voltage) input from the PCM 8. Four input ports and four output ports are formed on the side surface of the casing. The four input ports are the downstream end of the first auxiliary flow path 2a, the downstream end of the second auxiliary flow path 3a, the downstream end of the third auxiliary flow path 3b, and the third flow path 4 Connected to the downstream end. Further, the four output ports are connected to the input port 5 a of the cooling water pump 5.

  A notch is formed on the side surface of the valve body. The communication area S of the output port formed in the notch and the casing has a first auxiliary flow path 2a, a second auxiliary flow path 3a, a third auxiliary flow path 3b, and a third flow path. 4 is set individually. In the following description, the communication area with respect to the first auxiliary flow path 2a is referred to as “communication area S2a”, the communication area with respect to the second auxiliary flow path 3a is referred to as “communication area S3a”, and The communication area with respect to the flow path 3b is referred to as “communication area S3b”, and the communication area with respect to the third flow path 4 is referred to as “communication area S4”.

  The communication area S2a is constant in a small area near zero regardless of the rotation angle of the valve body (see FIG. 5), and the cylinder head 9b is not overcooled by suppressing the flow rate of cooling water to a small amount near zero. However, the flow rate necessary for cooling the high pressure EGR valve 11a and the intake shutter valve 11b is set to an area that can be secured.

  On the other hand, the communication area S3a, the communication area S3b, and the communication area S4 change continuously according to the rotation angle of the valve body (see FIG. 5).

  That is, the flow rate of the cooling water in the second auxiliary passage 3a changes in accordance with the change in the communication area S3a (hereinafter referred to as "the opening degree of the flow control valve 6 relative to the second auxiliary passage 3a"). To do.

  Further, the flow rate of the cooling water in the third auxiliary passage 3b changes in accordance with the change in the communication area S3b (hereinafter referred to as "the opening degree of the flow control valve 6 with respect to the third auxiliary passage 3b"). To do.

  Further, the flow rate of the cooling water in the third flow path 4 changes according to the change in the communication area S4 (hereinafter referred to as “the opening degree of the flow control valve 6 with respect to the third flow path 4”).

  The water temperature sensor 7 detects the temperature of the cooling water in the vicinity of the cylinder head 9 b in the first flow path 2. Information on the temperature detected by the water temperature sensor 7 is transmitted to the PCM 8.

  In addition to the engine control function and the intake / exhaust system control function described above, the PCM 8 has a valve control function for controlling the opening degree of the flow control valve 6 based on the temperature detected by the water temperature sensor 7, and a failure of the flow control valve 6. A failure state detecting function for detecting the engine 9 and an output limiting function for limiting the output of the engine 9 when a failure is detected by the failure state detecting function.

  First, the control (valve control function) of the flow control valve 6 by the PCM 8 will be described with reference to the flowchart of FIG.

  In the following description, control is performed from the state in which the opening degree of the flow rate control valve 6 with respect to the second auxiliary flow path 3a, the third auxiliary flow path 3b, and the third flow path 4 is zero (closed). Shall be started.

  First, the PCM 8 inputs the temperature T of the cooling water in the cylinder head 9b from the water temperature sensor 7 (step S51).

  Next, the PCM 8 determines whether or not the input temperature T is lower than the first temperature threshold T1 (step S52). Here, the first temperature threshold value T1 is a temperature lower than the temperature (for example, approximately 80 ° C.) when the engine 9 transitions from the cold state to the warm state after the cold start of the engine 9, that is, the engine is warming up ( The temperature is before completion of warming-up, for example, 50 ° C. (see FIG. 8).

  When it is determined that the temperature T is lower than the first temperature threshold T1 (YES in step S52), the PCM 8 determines the opening degree of the flow control valve 6 with respect to the second auxiliary machine flow path 3a and the third auxiliary machine. By maintaining the opening degree of the flow control valve 6 with respect to the flow path 3b at zero (see A0 in FIG. 8), the upstream side of the branch point P1 in the first flow path 2 (hereinafter referred to as “upstream in the first flow path 2”). Control is performed to limit the flow rate of the cooling water flowing through the side flow path 2b "(the flow rate of the cooling water flowing through the cylinder head 9b) (step S53). Thereby, the flow rate of the cooling water flowing through the upstream flow channel 2b in the first flow channel 2 becomes equal to the flow rate of the cooling water flowing through the first auxiliary flow channel 2a (path (1)), and a small amount near zero. (See A1 in FIG. 9). Therefore, the temperature drop of the cylinder head 9b is suppressed, and the temperature of the cylinder head 9b gradually rises (first water flow state in FIG. 9). In step S53, the PCM 8 controls the opening of the flow control valve 6 with respect to the third flow path 4 to zero. Thereby, the temperature drop of the cylinder block 9a is suppressed, and the temperature of the cylinder block 9a gradually increases. After step S53, the process returns to step S51.

  When it is determined in step S52 that the temperature T is equal to or higher than the first temperature threshold T1 (NO in step S52), the PCM 8 has a temperature T lower than the second temperature threshold T2 (for example, 80 ° C., see FIG. 8). Is determined (step S54). Note that the second temperature threshold T2 is higher than the first temperature threshold T1.

  When it is determined that the temperature T is lower than the second temperature threshold T2 (YES in step S54), the PCM 8 increases the opening degree of the flow control valve 6 with respect to the second auxiliary flow path 3a. Control is performed to release the restriction on the flow rate of the cooling water in the first flow path 2 (step S55). After step S55, the process returns to step S51.

  Here, the control performed in step S55 will be described in detail with reference to the flowchart of FIG. First, the PCM 8 has a predetermined opening degree (for example, about 1/3 of the target opening degree) in which the opening degree of the flow control valve 6 with respect to the second auxiliary flow path 3a is less than the target opening degree. The flow rate control valve 6 is controlled so as to satisfy (A2) (step S61). The “target opening” referred to here is the target opening at the time of warm, and means the maximum opening (fully opened) of the flow control valve 6 with respect to the second auxiliary flow path 3a.

  As a result, the cooling water starts to flow a little in the second auxiliary flow path 3 a, and the cooling water that has flowed through the second auxiliary flow path 3 a flows into the first flow path 2 via the cooling water pump 5. That is, the flow rate of the cooling water flowing through the upstream flow path 2b in the first flow path 2 is the same as the flow rate of the cooling water flowing through the first auxiliary flow path 2a (path (1)) and the second auxiliary flow path. It becomes the sum of the flow rates of the cooling water flowing through 3a (path (2)), and the flow rate is increased compared to that in step S53 (see A3 in FIG. 9). However, since the opening degree of the flow control valve 6 with respect to the second auxiliary machine flow path 3a is not suddenly fully opened, for example, it is set to about 1/3 of the full opening degree. Release of the flow restriction is started gradually.

  Next, the PCM 8 determines whether or not the temperature T detected by the water temperature sensor 7 is equal to or higher than a third temperature threshold T3 (for example, 75 ° C., see FIG. 8) higher than the first temperature threshold T1 and lower than the second temperature threshold T2. (Step S62).

  When it is determined that the temperature T is equal to or higher than the third temperature threshold T3 (YES in step S62), the PCM 8 determines that the opening degree of the flow control valve 6 with respect to the second auxiliary flow path 3a is the target when the temperature is warm. The flow control valve 6 is controlled so as to be the opening degree (see A4 in FIG. 8) (step S63). As a result, the flow rate of the cooling water flowing through the second auxiliary flow path 3a (path (2)) increases to the target flow rate during warmth (the maximum flow rate in the second auxiliary flow path 3a). As a result, the flow rate of the cooling water flowing through the upstream flow path 2b in the first flow path 2 also increases (see A5 in FIG. 9). Accordingly, since the flow rate gradually increases in two stages of steps S61 and S63, the restriction on the flow rate in the first flow path 2 is gradually released (second water flow state in FIG. 9).

  Returning to FIG. 6, when it is determined in step S54 that the temperature T is equal to or higher than the second temperature threshold T2 (NO in step S54), the PCM 8 determines that the temperature T is the fourth temperature threshold T4 (for example, 95 ° C.). (See FIG. 8), it is determined whether it is less (step S56). Note that the fourth temperature threshold T4 is higher than the third temperature threshold T3.

  When it is determined that the temperature T is lower than the fourth temperature threshold T4 (YES in step S56), the PCM 8 performs control to increase the opening degree of the flow control valve 6 with respect to the third flow path 4 (step S57). ). After step S57, the process returns to step S51.

  Here, the control performed in step S57 will be described in detail with reference to the flowchart of FIG. First, the PCM 8 has a predetermined opening degree (for example, an opening degree that is about a half of the target opening degree. For example, refer to A6 in FIG. 8). ) To control the flow rate control valve 6 (step S61). Thereby, a little cooling water starts flowing through the third flow path 4, and the cooling water flowing through the third flow path 4 flows into the first flow path 2 and the third flow path 4 via the cooling water pump 5 (FIG. 9 A7). The “target opening” here is the target opening at the time of warm, and means the maximum opening (fully opened) of the flow control valve 6 with respect to the third flow path 4.

  Next, the PCM 8 determines whether or not the temperature T detected by the water temperature sensor 7 is equal to or higher than a fifth temperature threshold T5 (for example, 85 ° C., see FIG. 8) higher than the second temperature threshold T2 and lower than the fourth temperature threshold T4. (Step S62).

  When it is determined that the temperature T is equal to or higher than the fifth temperature threshold value T5 (YES in step S62), the PCM 8 determines that the opening degree of the flow control valve 6 with respect to the third flow path 4 is the target opening degree (A8 in FIG. 8). The flow rate control valve 6 is controlled so as to be (see A9 in FIG. 9) (step S63). Thereby, the flow volume of the cooling water which flows through the 3rd flow path 4 (path | route (3)) increases to the target flow volume (maximum flow volume in the 3rd flow path 4) at the time of warm. That is, the flow rate of the cooling water flowing out from the third flow path 4 gradually increases in two stages of steps S61 and S63 (third water flow state in FIG. 9).

  Returning to FIG. 6, when it is determined in step S56 that the temperature T is equal to or higher than the fourth temperature threshold T4 (NO in step S56), the PCM 8 controls the flow control valve for the third auxiliary flow path 3b. Control to increase the opening of 6 is performed (step S58). After step S58, the process returns to step S51.

  Here, the control performed in step S58 will be described in detail with reference to the flowchart of FIG. First, the PCM 8 has a predetermined opening degree (for example, an opening degree about 1/2 of the target opening degree) in which the opening degree of the flow control valve 6 with respect to the third auxiliary flow path 3b is less than the target opening degree. The flow rate control valve 6 is controlled so as to satisfy A10) (step S61). The “target opening” referred to here is the target opening during warming, and means the maximum opening (fully opened) of the flow control valve 6 with respect to the third auxiliary flow path 3b.

  Thereby, the flow volume of the cooling water which flows through the upstream flow path 2b in the 1st flow path 2 increases compared with the time of step S55 (refer A11 of FIG. 9). However, since the opening degree of the flow control valve 6 with respect to the third auxiliary flow path 3b is not suddenly fully opened, for example, the opening degree is about ½ of the full opening degree. The restriction on the flow rate is released gradually.

  Next, the PCM 8 determines whether or not the temperature T detected by the water temperature sensor 7 is equal to or higher than a sixth temperature threshold T6 (for example, 100 ° C., see FIG. 8) higher than the fourth temperature threshold T4 (step S62).

  When it is determined that the temperature T is equal to or higher than the sixth temperature threshold T6 (YES in step S62), the PCM 8 determines that the opening degree of the flow control valve 6 with respect to the third auxiliary flow path 3b is the target when the temperature is warm. The flow control valve 6 is controlled so as to be the opening degree (see A12 in FIG. 8) (step S63). As a result, the flow rate of the cooling water flowing through the third auxiliary flow path 3b (path (4)) increases to the target flow rate during warmth (the maximum flow rate in the third auxiliary flow path 3b), and the increase As a result, the flow rate of the cooling water in the first flow path 2 also increases (see A13 in FIG. 9). That is, since the flow rate gradually increases in two stages of steps S61 and S63, the restriction on the flow rate in the first flow path 2 is gradually released (fourth water flow state in FIG. 9).

  Next, the failure state detection function and the output restriction function of the PCM 8 will be described.

  The PCM 8 stores in advance a plurality of output restriction pattern maps 40 (see FIG. 10) used when the output of the engine 9 is restricted.

  As shown in FIGS. 10A and 10B, the output restriction pattern map 40 is set for each engine speed. For example, the engine speed shown in FIG. 10A is 1600 rpm. Output restriction pattern map 40A and an output restriction pattern map 40B when the engine speed is 4500 rpm shown in FIG. 10B.

  The output restriction pattern map 40A and the output restriction pattern map 40B are two examples of the many output restriction pattern maps 40 stored in the PCM 8, and the PCM 8 is an output restriction pattern map corresponding to another engine speed. 40 is also stored in advance.

  Hereinafter, the output restriction pattern map 40A will be described, but the following description also applies to the output restriction pattern map 40B.

  An output restriction pattern map 40A shown in FIG. 10A has a plurality of engine output restriction patterns L1 to L4. Engine output restriction patterns (hereinafter referred to as “output restriction patterns”) L1 to L4 are preset in a polygonal line or a curve for each rotation angle level of the flow control valve 6 (in the example shown in FIG. 10, a polygonal line). The relationship between the temperature (horizontal axis) of the cooling water flowing through the cylinder head 11b and the limit value (vertical axis) of the fuel injection amount to the engine 9 is defined. The limit value of the fuel injection amount is an upper limit value of the fuel injection amount. The engine 9 is controlled so as to inject fuel with a fuel injection amount equal to or less than the limit value.

  Specifically, the output restriction pattern map 40A includes a first opening level output restriction pattern L1 in which the rotation angle of the flow control valve 6 is less than the first angle threshold (see FIG. 5), and the rotation angle is the first angle. Output limit pattern L2 for the second opening level that is greater than or equal to the threshold and less than the second angle threshold, output limit pattern L3 for the third opening level that is greater than or equal to the second angle threshold and less than the third angle threshold, and rotation angle Has a fourth opening level output restriction pattern L4 that is greater than or equal to the third angle threshold.

  In order from the highest total opening level of the flow control valve 6 (total opening level of the flow control valve 6 with respect to the paths (1) to (4)), the output restriction pattern L4 of the fourth opening, the third opening The output restriction pattern L3, the output restriction pattern L2 of the second opening, and the output restriction pattern L1 of the first opening are arranged.

  In the output restriction pattern map 40A, the output restriction patterns L1 to L4 are defined such that the higher the total opening level of the flow control valve 6, the higher the limit value of the fuel injection amount at the same coolant temperature (FIG. 10). (See (a)).

  For example, in the section where the coolant temperature is 110 to 120 ° C., the limit value of the fuel injection amount set in the output restriction pattern L4 of the fourth opening level is the output restriction pattern L1 of the first opening level and the second opening level. It is higher than the limit value of the fuel injection amount set in the output limit pattern L2 of the engine level and the output limit pattern L3 of the third opening level.

  The output restriction patterns L1 to L4 are set in advance by performing experiments and simulations.

The output restriction pattern map 40A has a maximum fuel injection amount line Ls. The maximum fuel injection amount line Ls is preset at a different height for each engine speed (see also the output restriction pattern map 40B). The height of the maximum fuel injection amount line Ls indicates the maximum fuel injection amount, and the value is a value that should not be exceeded regardless of the rotation angle (a constant value regardless of the rotation angle). Is set. In the output restriction pattern map 40A, the maximum fuel injection amount is set to about 58 mm ³ / stroke.

  Next, the failure state detection operation and the output restriction operation performed in the PCM 8 will be described with reference to FIG.

  Here, the failure detection operation of the flow control valve 6 performed in parallel with the control in step S55 of FIG. 6 will be described. In parallel with the control in steps S53, S55, S57, and S58 in FIG. 6, a failure detection operation similar to that in FIG. 11 is performed.

  As shown in FIG. 11, first, the PCM 8 reads the control rotation angle output in step S55 of FIG. 6 (step S91). The “control rotation angle” is a control value of the rotational opening degree of the flow control valve 6 output from the PCM 8 to the flow control valve 6 in step S55.

  Next, the PCM 8 reads the rotation angle of the flow control valve 6 (hereinafter referred to as “detected rotation angle”) detected by a rotation angle sensor (not shown) provided in the flow control valve 6 (step S92).

  Next, the PCM 8 determines whether or not the difference between the control rotation angle and the detected rotation angle is greater than or equal to a predetermined difference threshold value (step S93).

  If it is determined that the difference between the control rotation angle and the detected rotation angle is equal to or greater than the difference threshold (YES in step S93), the PCM 8 increments the count value by one in a failure determination counter (not shown) (step S94). .

  Next, the PCM 8 determines whether or not the count value in the failure determination counter is equal to or greater than a predetermined count threshold value (step S95).

  If it is determined that the count value in the failure determination counter is equal to or greater than a predetermined count threshold value (YES in step S95), the PCM 8 sets the failure determination flag to “1” (step S96). Note that the failure determination flag is set to “0” in the state before performing the process of step S91.

  Next, the PCM 8 performs an output limiting operation of the engine 9 (step S97).

  When it is determined in step S93 that the difference between the control rotation angle and the detected rotation angle is less than the difference threshold value (NO in step S93), the PCM 8 decrements the count value of the failure determination counter by one (step S93). S98), the process proceeds to step S95.

  If it is determined in step S95 that the count value in the failure determination counter is less than the count threshold (NO in step S95), the PCM 8 returns to step S91 and continues the process.

  Next, the output limiting operation of the engine 9 performed in step S97 will be described with reference to FIG.

  As shown in FIG. 12, first, the PCM 8 determines whether or not the failure determination flag is “1” (step S101).

  When it is determined that the failure determination flag is “1” (YES in step S101), the PCM 8 detects the rotation angle of the flow control valve 6 detected by the rotation angle sensor (hereinafter referred to as “failure rotation angle”). Is read (step S102).

  Next, the PCM 8 reads the temperature of the cooling water detected by the water temperature sensor 7 and the engine speed (step S103).

  Next, the PCM 8 selects and reads the output restriction pattern map 40 corresponding to the read engine speed from the plurality of output restriction pattern maps 40 (step S104). For example, when the engine speed is 1600 rpm, the output restriction pattern map 40A is selected and read.

Next, the PCM 8 reads the limit value of the fuel injection amount according to the failure rotation angle and the coolant temperature with reference to the output restriction pattern map 40 selected and read (step S105). For example, when the failure rotation angle is the third opening level and the cooling water temperature is 110 ° C., the limit value (for example, 40 mm ³ / stroke) of the fuel injection amount is read with reference to the output limit pattern L3 (FIG. 10). (See (a)).

  Next, the PCM 8 controls the engine 9 for a predetermined time with a fuel injection amount equal to or less than the read limit value of the fuel injection amount (step S106). When a predetermined time has elapsed, the PCM 8 returns to step S102 and continues the process.

  In addition, after the flow control valve 6 breaks down, the valve body of the flow control valve 6 does not rotate, and the failure rotation angle may be constant over time (the angle is fixed). It is also conceivable that after the failure, the valve body of the flow control valve 6 rotates and the failure rotation angle changes with time.

  As described above, according to the present embodiment, when the failure of the flow control valve 6 is detected, the PCM 8 increases the output limit value (engine output) of the engine 9 as the flow rate of the cooling water flowing through the cylinder head 9b increases. Set the upper limit value to a large value. When the flow rate of the cooling water flowing through the cylinder head 9b is large, overheating of the engine 9 can be prevented without setting the output limit value of the engine 9 to a small value. Therefore, according to the present embodiment, when the flow rate control valve 6 breaks down, the retreat travel can be performed without preventing the output performance of the engine 9 more than necessary while preventing the engine 9 from overheating.

  Further, in the present embodiment, the output limit value of the engine 9 is set to a larger value as the temperature detected by the water temperature sensor 7 is lower. When the temperature of the cooling water flowing through the cylinder head 9b is low, there is room in terms of temperature and time before the engine 9 is overheated. Therefore, the effect of performing the retreat travel without reducing the output performance of the engine 9 more than necessary can be achieved more reliably.

In this embodiment, when the temperature detected by the water temperature sensor 7 is lower than a predetermined temperature Tk (see FIG. 10A), the output limit value of the engine 9 is set to a predetermined maximum value ( For example, it is set to about 58 mm ³ / stroke), so that it is possible to sufficiently suppress a decrease in output during retreat travel. The “predetermined temperature” referred to here is, for example, the cooling water temperature Tk at the intersection K between the output restriction pattern L1 and the maximum injection amount line Ls in FIG.

  In the present embodiment, the output limit value of the engine 9 is set to a larger value as the engine speed is lower. The lower the engine speed, the smaller the amount of heat generated by the engine 9 per unit time. Therefore, the effect of performing the retreat travel without reducing the output performance of the engine 9 more than necessary can be achieved more reliably.

  In the present embodiment, the failure of the flow control valve 6 is detected based on the difference between the detected rotation angle detected by the rotation angle sensor and the control rotation angle output from the PCM 8. If the difference between the detected rotation angle and the control rotation angle is large, it is considered that the flow control valve 6 has failed. Therefore, the failure of the flow control valve 6 can be detected effectively.

  Further, in this embodiment, when the cooling water flows through the radiator 11f, the output limit value of the engine 9 is set to a larger value than when the cooling water does not flow through the radiator 11f. When the cooling water flows through the radiator 11f, the cooling water is cooled by the radiator 11f, so that the engine 9 can be effectively cooled. Therefore, by changing the output limit value of the engine 9 depending on whether or not the cooling water flows through the radiator 11f, the effect of performing the retreat travel without lowering the output performance of the engine 9 more than necessary is obtained. It can be played reliably.

  In the present embodiment, the PCM 8 stores a plurality of output restriction patterns L <b> 1 to L <b> 4 set in advance for each opening level of the flow control valve 6. When a failure of the flow control valve 6 is detected, an engine output restriction pattern corresponding to the opening degree of the flow control valve 6 is selected from the plurality of engine output restriction patterns L1 to L4, and the fuel injection amount is set. Restrict. If the opening level of the flow control valve 6 is different, the cooling capacity of the engine 9 is also different. Therefore, according to this configuration, it is possible to finely limit the output of the engine during retreat according to the cooling capacity of the engine 9.

  Further, in this embodiment, the limit value of the fuel injection amount when the opening level of the flow control valve 6 is high is set high. The larger the opening degree of the flow control valve 6, the higher the cooling capacity of the engine 9. Therefore, it is possible to appropriately limit the output so as not to reduce the output of the engine 9 during the evacuation travel as much as possible within a safe range.

  In the present embodiment, when the temperature of the cooling water flowing through the cylinder head 9b is equal to or higher than the first temperature threshold T1, the flow rate control valve 6 for the second auxiliary flow path 3a and the third auxiliary flow path 3b is used. Is controlled so as to gradually increase to a predetermined target opening, so that the restriction on the flow rate of the cooling water flowing through the cylinder head 9b is gradually released, and the temperature of the cylinder head 9b is lowered (supercooled). Can be suppressed.

DESCRIPTION OF SYMBOLS 1 Engine cooling system 2 1st flow path 2a 1st auxiliary machine flow path 2b Upstream flow path 3 2nd flow path 3a 2nd auxiliary machine flow path 3b 3rd auxiliary machine flow path 4 3rd flow path 5 Cooling water pump 5a Cooling water pump inlet port 5b Cooling water pump outlet port 6 Flow control valve 7 Water temperature sensor 8 PCM
9 Engine 9a Cylinder block 9b Cylinder head 11 Auxiliary machine 11a High pressure EGR valve 11b Intake shutter valve 11c Low pressure EGR cooler 11d Low pressure EGR valve 11e Heater core 11f Radiator 11g Oil cooler 11h ATF cooler 40, 40A, 40B Output restriction pattern map L Output restriction pattern

Claims (8)

A cooling water passage including a passage through the engine and circulating the cooling water;
A cooling water pump for circulating cooling water in the cooling water flow path;
A flow rate control valve for controlling the flow rate of the cooling water flowing through the cooling water flow path;
Valve control means for controlling the opening of the flow control valve;
A failure state detecting means for detecting a failure of the flow control valve;
When a failure is detected by the failure detection means, an output limit value is set for setting the engine output limit value and limiting the engine output to the output limit value or less.
The engine cooling system according to claim 1, wherein the output restriction means sets the output restriction value to a larger value as the flow rate of the cooling water flowing through the engine increases. Temperature detecting means for detecting the temperature of the cooling water flowing through the engine;
2. The engine cooling system according to claim 1, wherein the output limiting unit sets the output limiting value to a larger value as the temperature detected by the temperature detecting unit is lower. 3.   The output restriction means sets the output restriction value to a predetermined maximum value when the temperature detected by the temperature detection means is lower than a predetermined temperature. The engine cooling system according to 2.   The engine cooling system according to any one of claims 1 to 3, wherein the output limiting means sets the output limiting value to a larger value as the engine speed is lower. The flow rate control valve is a rotary valve having a predetermined correlation between the opening degree and the rotation angle,
The cooling system further includes a rotation angle detection means for detecting a rotation angle of the flow rate control valve,
The failure state detection means is a difference between a detected rotation angle detected by the rotation angle detection means and a control rotation angle that is a control value of the rotation angle output from the valve control means to the flow rate control valve. The engine cooling system according to any one of claims 1 to 4, wherein a failure of the flow control valve is detected on the basis of the above. The cooling water flow path includes a radiator flow path that passes through a radiator,
The output control means is configured such that when the flow control valve is opened with respect to the flow path through the radiator, the output limit value is greater than when the flow control valve is not opened with respect to the flow path through the radiator. The engine cooling system according to claim 1, wherein a large value is set. The cooling water flow path includes a radiator flow path that passes through a radiator,
The output limiting means is preset for each opening level of the flow rate control valve with respect to the flow path through the radiator, and the relationship between the temperature of the coolant flowing through the engine and the limit value of the fuel injection amount to the engine. A plurality of prescribed engine output restriction patterns are stored, and one of the plurality of engine output restriction patterns corresponding to the opening level of the flow control valve when a failure is detected by the failure detection means. The engine cooling system according to any one of claims 1 to 6, wherein one engine output restriction pattern is selected and the fuel injection amount is restricted based on the selected engine output restriction pattern.   In the plurality of engine output restriction patterns, the higher the opening level of the flow control valve with respect to the radiator passage, the higher the limit value of the fuel injection amount at the same cooling water temperature is set. The engine cooling system according to claim 7.

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