JP4306544B2 - Internal combustion engine failure determination system - Google Patents

Description

  The present invention relates to a failure determination system for determining a failure of a heat storage system in an internal combustion engine having the heat storage system.

  If the warm-up is not performed quickly at the start of the internal combustion engine, there is a risk that the emission will deteriorate. Accordingly, a heat medium such as cooling water warmed by heat exchange with the internal combustion engine during operation of the internal combustion engine is kept warm, and the stored heat medium is supplied to the internal combustion engine when the internal combustion engine is started. Thermal storage systems are used to promote engine warm-up.

Here, if the above heat storage system fails, the engine startability of the internal combustion engine deteriorates and the emission at the time of engine start deteriorates. Therefore, it is necessary to determine whether or not the heat storage system is in a failure state. Therefore, when the temperature increase rate of the heat medium flowing through the internal combustion engine when the heat medium is supplied to the internal combustion engine by the heat storage system is low even though the temperature of the heat medium stored warmly is sufficiently high, A technique for determining that the heat storage system is in a failure state is disclosed (for example, see Patent Document 1).
JP-A-11-182307 JP 2003-3939 A

  In an internal combustion engine, a heat medium such as cooling water heated by heat exchange with the internal combustion engine during operation is kept warm, and the stored heat medium is supplied to the internal combustion engine when the internal combustion engine is started. A heat storage system that promotes warm-up of the plant is used. Here, when determining whether or not the heat storage system is in a failure state, it is possible to directly or indirectly use the temperature increase of the heat medium supplied to the internal combustion engine by the heat storage system.

  However, the temperature of the heat medium supplied to the internal combustion engine by the heat storage system is not always a constant temperature. Further, the temperature of the heat medium flowing through the internal combustion engine is increased according to the temperature of the stored heat medium, in other words, the heat medium. The degree of the engine temperature rise due to the temperature and the temperature rise of the elements constituting the heat storage system vary. As a result, it is difficult to accurately determine the failure of the heat storage system.

  In view of the above problems, an object of the present invention is to provide a failure determination system for an internal combustion engine that more accurately determines whether or not the heat storage system is in a failure state in an internal combustion engine having a heat storage system.

  In the present invention, in order to solve the above-described problem, first, the flow rate of the heat medium flowing through the circulation passage constituting the heat storage system is estimated based on the temperature rise of the heat medium, and based on the estimated flow rate. When the failure of the heat storage system is determined, the flow rate of the heat medium estimated based on the heat medium temperature in the heat storage tank constituting the heat storage system is corrected. Accordingly, it is possible to estimate the flow rate of the heat medium in consideration of the degree of temperature rise of the heat medium flowing through the internal combustion engine depending on the temperature of the stored heat medium. As a result, the accuracy of failure determination based on the flow rate of the heat medium can be further increased.

In view of this, the present invention relates to a failure determination system for an internal combustion engine. A heat storage system, a heat medium pump that supplies the heat medium stored in the heat storage tank to the circulation passage, and the heat medium when the heat medium is supplied to the circulation passage by the heat medium pump. A flow rate estimating means for estimating a flow rate of the heat medium flowing through the circulation path based on a temperature rise of the heat medium flowing through a predetermined portion of the circulation path, and the heat medium when the heat medium is supplied to the circulation path by the heat medium pump Based on the temperature of the heat medium in the heat storage tank, the flow rate correction means for correcting the heat medium flow rate estimated by the flow rate estimation means, and the heat medium flow rate corrected by the flow rate correction means Zui by and a failure determining means for determining whether or not the heat storage system is in a fault state.

  In the internal combustion engine having the heat storage system configured as described above, the heat medium pumped by the heat medium pump circulates between the internal combustion engine and the heat storage tank via the circulation passage. The heat storage tank stores the heat medium in a heat-retaining state, and the stored heat medium is supplied to the internal combustion engine through the circulation passage as necessary. For example, a relatively high-temperature heat medium stored in a heat storage tank is supplied to the internal combustion engine in order to reduce friction at the start of the engine and to suppress deterioration of emissions. That is, the temperature of the internal combustion engine is controlled by heat exchange between the internal combustion engine and the heat medium.

  The estimation of the heat medium flow rate by the flow rate estimation means is performed based on the temperature increase rate of the heat medium flowing through the predetermined part of the circulation passage. This is because the rise in the temperature of the heat medium means that the heat medium having a relatively high temperature has reached a predetermined site, and therefore the heat medium flow rate can be estimated by the arrival of the heat medium.

  Here, the predetermined part is a part where the temperature of the heat medium flowing through the circulation passage can be detected, and may be one part or two or more parts. For example, when the predetermined part is one part, it is possible to estimate the flow rate of the heat medium flowing through the circulation passage based on the time from the start of supply of the heat medium by the heat medium pump to the arrival of the heat medium at the predetermined part. is there. Moreover, when the predetermined part is two or more parts, it is possible to estimate the flow rate of the heat medium flowing through the circulation passage based on the difference in arrival time of the heat medium for each part.

  Here, according to the heat medium temperature stored in the heat storage tank, the degree of the temperature increase of the heat medium flowing through the circulation passage when the heat medium is supplied by the heat medium pump is different. That is, when a relatively high-temperature heat medium is supplied, the temperature increase rate of the heat medium flowing through the circulation path is high, whereas when a relatively low-temperature heat medium is supplied, the heat medium flowing through the circulation path The rate of temperature rise is low. Since the temperature of the heat medium stored in the heat storage tank is not always constant when the heat medium is supplied by the heat medium pump, the error included in the flow rate estimated by the flow rate estimation means is relatively large. .

  Therefore, by correcting the heat medium flow rate estimated by the flow rate estimation unit based on the heat medium temperature stored in the heat storage tank when the heat medium pump supplies the heat medium by the flow rate correction unit, the included error can be reduced. It can be reduced.

  And it becomes possible for a failure determination means to raise the determination precision by determining whether a thermal storage system is in a failure state based on the heat medium flow volume corrected by the flow volume correction means. The failure determination means determines that the circulation path constituting the heat storage system, damage to the heat storage tank, malfunction of the heat medium pump, or the like is a failure of the heat storage system when the heat medium flow rate is too low or too high.

Here, in the internal combustion engine failure determination system, the predetermined part is a first part of the circulation passage and a second part downstream of the first part, and the heat medium flows through the first part. And a second temperature detecting means for detecting the temperature of the heat medium flowing through the second part, and the flow rate estimating means is configured to detect the heat medium by the heat medium pump. After the supply to the circulation passage, the time for the heat medium temperature detected by the first temperature detection means to reach the first predetermined temperature and the heat medium temperature detected by the second temperature detection means are the second predetermined temperature. The flow rate of the heat medium flowing through the circulation passage may be estimated based on the time difference from the time to reach the temperature.

  In other words, it is detected that the heat medium has reached the two parts of the circulation passage by increasing the temperature of the heat medium flowing through the first part and the second part. Then, by dividing the volume of the circulation path between the first part and the second part by the difference in arrival time, it is possible to estimate the flow rate of the heat medium flowing through the circulation path. Therefore, the first predetermined temperature and the second predetermined temperature are the heat medium temperature due to the flow of the heat medium when the first temperature detection means and the second temperature detection means detect the temperature rise of the heat medium flowing through each part. This is a threshold value for detecting the arrival of a relatively high-temperature heat medium by eliminating the minute fluctuations in the above.

  The first part is a part of the circulation passage in the vicinity of the outlet of the heat storage tank where the heat storage tank and the circulation path are connected, and the second part is a part of the circulation passage in the internal combustion engine. It may be. It should be noted that the heat medium flow rate can be estimated also at other parts based on the temperature rise of the heat medium flowing through the part.

  Here, in the internal combustion engine failure determination system up to the above, the flow rate correction means, as the heat medium temperature in the heat storage tank when the heat medium is supplied to the circulation passage by the heat medium pump decreases, The heat medium flow rate estimated by the flow rate estimation means may be corrected to a larger value.

  As the heat medium temperature in the heat storage tank becomes lower, the rate of increase in the heat medium temperature at a predetermined part indicating that the heat medium has reached the predetermined part of the circulation passage becomes smaller. In particular, when detecting an increase in the heat medium temperature at the first part and the second part, the heat medium temperature reaching the second part on the downstream side is lower than the heat medium temperature reaching the first part. The rate of increase of the heat medium temperature at the site is further reduced.

  As a result, as the temperature of the heat medium stored in the heat storage tank decreases, the timing for detecting that the heat medium has reached the predetermined part is delayed, and the flow rate of the heat medium in the circulation passage is constant. The heat medium flow rate estimated by the flow rate estimating means decreases as the temperature of the heat medium stored in the heat storage tank decreases. Therefore, by correcting the heat medium flow rate by the flow rate correcting means as described above, it is possible to determine the failure with higher accuracy.

  Here, the heat medium temperature in the heat storage tank, which is a reference for correcting the heat medium flow rate by the flow rate correcting means, has passed a predetermined time after the heat medium is supplied to the circulation passage by the heat medium pump. The heat storage tank may be set to the temperature of the heat medium flowing through the portion of the circulation passage near the outlet of the heat storage tank where the heat storage tank and the circulation passage are connected.

  The predetermined time refers to the temperature of the heat medium flowing through the circulation passage near the outlet of the heat storage tank as the heat medium in the heat storage tank is gradually supplied to the circulation passage. This is the time required to reach the same temperature as the medium temperature. Therefore, it is possible to correct the estimated heat medium flow rate based on the temperature of the heat medium flowing through the portion of the circulation passage near the outlet of the heat storage tank after a predetermined time has elapsed.

  Here, when the heat medium flow rate corrected by the flow rate correction unit is less than a predetermined flow rate, the failure determination unit determines that air has entered the heat medium pump, and the heat storage system is in a failure state. The determination of whether or not may be interrupted.

  The predetermined flow rate is a heat medium flow rate determined by the pumping capacity of the heat medium pump. Therefore, for example, the predetermined flow rate includes the outside air temperature, the intake air temperature of the internal combustion engine, the heat medium temperature in the circulation passage when the internal combustion engine is in an engine stop state, and the battery that supplies power to the heat medium pump. It may be determined based on at least one of the remaining voltages. Since these parameters are parameters related to the pumping capacity of the heat medium pump, the predetermined flow rate can be determined based on any one or a plurality of these parameters.

  When the failure determination of the heat storage system is performed based on the flow rate corrected by the flow rate correction means, when the supply of the heat medium at a predetermined flow rate that is originally possible by the heat medium pump has not been achieved, It is possible to determine that air is mixed in. Therefore, in such a case, it is possible to avoid the erroneous determination in the failure determination as much as possible by not performing the failure determination of the other heat storage system by the failure determination means.

  This mixing of air into the heat medium pump is not a fatal failure of the heat storage system, but is a temporary malfunction, so if the heat medium pump is driven for a certain period of time, normally the mixed air is not It is discharged and the heat pump capacity is restored. However, during that period, the pumping capacity of the heat medium pump is still lowered, and the effect of warming up the internal combustion engine by the heat storage system is also reduced.

  Therefore, in the above-described internal combustion engine failure determination system, when it is determined by the failure determination means that air has been mixed into the heat medium pump, the driver of the vehicle on which the internal combustion engine is mounted is informed to the inside of the heat medium pump. An air mixing notification means for notifying that air is mixed may be further provided.

  As a result, it is possible to prompt the operator to remove the air mixed in the heat medium pump by his own work. The notification of air mixing by the air mixing notification means may be issued immediately after the failure determination means determines that air has been mixed, or after the failure determination means detects several times of air mixing. May be.

  Next, in the present invention, in order to solve the above-described problem, the heat storage system is configured when a failure of the heat storage system is determined based on the temperature increase rate of the heat medium flowing through the circulation passage configuring the heat storage system. The reference value for failure determination is changed based on the heat medium temperature in the heat storage tank. Accordingly, it is possible to determine the failure of the heat storage system in consideration of the difference in the temperature increase rate of the heat medium flowing through the internal combustion engine due to the difference in the stored heat medium temperature.

  Accordingly, the present invention provides a passage through which a heat medium circulates and is formed via an internal combustion engine, a heat storage tank that retains a part of the heat medium that circulates through the circulation passage, and the heat storage tank. A heat storage system that supplies the heat medium stored in the circulation passage to the circulation passage, and heat flowing through a predetermined portion of the circulation passage when the heat medium is supplied to the circulation passage by the heat medium pump. A failure determination system for an internal combustion engine that determines that the heat storage system is in a failure state when a temperature increase rate of the medium is lower than a predetermined increase rate, wherein the heat medium is circulated by the heat medium pump. The apparatus further includes correction means for correcting the predetermined increase rate based on the heat medium temperature in the heat storage tank when supplied to the passage.

The predetermined part is a part capable of detecting the temperature of the heat medium flowing through the circulation passage, and may be one part or two or more parts. The predetermined rate of increase is the rate of temperature increase of the heat medium that is originally obtained at a predetermined site when the heat medium is supplied to the internal combustion engine by the heat storage system. Therefore, in the above-described failure determination system for an internal combustion engine, when the temperature increase rate of the heat medium flowing through the predetermined portion of the circulation passage is lower than the predetermined increase rate, the heat medium that should be originally performed is not supplied. Therefore, it is determined that any one of the heat storage systems is in a failure state.

  Here, as described above, the rate of increase of the heat medium temperature at the predetermined portion varies according to the heat medium temperature stored in the heat storage tank when the heat medium is supplied by the heat medium pump. Therefore, if the predetermined rate of increase is constant regardless of the temperature of the heat medium stored in the heat storage tank, it is difficult to accurately determine the failure of the heat storage system. Therefore, the correction unit can correct the predetermined increase rate according to the temperature of the heat medium stored in the heat storage tank, thereby making it possible to determine the failure of the heat storage system with higher accuracy.

  Therefore, the correction means corrects the predetermined increase rate to a smaller value as the heat medium temperature in the heat storage tank when the heat medium is supplied to the circulation passage by the heat medium pump is decreased. Good. Thereby, the failure determination of the heat storage system with higher accuracy according to the heat medium temperature in the heat storage tank can be performed.

  According to the present invention, in an internal combustion engine having a heat storage system, it is possible to determine with high accuracy whether or not the heat storage system is in a failure state.

  Here, an embodiment of a failure determination system for an internal combustion engine according to the present invention will be described based on the drawings.

  FIG. 1 is a diagram schematically showing a heat storage system of an internal combustion engine 1 including a heat storage tank 8. 1 indicates the main flow direction of the cooling water when the cooling water, which is the heat medium stored in the heat storage tank 8, is supplied to the internal combustion engine 1.

  The internal combustion engine 1 is an internal combustion engine mainly composed of a cylinder head 2 and a cylinder block 3, and has a circulation passage S1 through which cooling water flows. The circulation passage S <b> 1 is a passage through which cooling water circulates from the cylinder head 2 in the order of the branch point C <b> 1, the flow rate adjusting valve 17, the radiator 9, the mechanical pump 10, the branch point C <b> 3, and the cylinder block 3. The cooling water is circulated in the circulation passage S1 mainly by the mechanical pump 10. The mechanical pump 10 is a mechanical pump in which the engine output of the internal combustion engine 1 acts as its driving force. The flow rate adjusting valve 17 is a valve for adjusting the flow rate of the cooling water flowing into the radiator 9.

  Next, in the heat storage system of the internal combustion engine 1 shown in FIG. 1, the flow path switching valve 5, the heat storage tank 8, the electric pump 7, the branch point C2, the branch point C4, the branch point C5, the branch point C3 from the branch point C1. A circulation passage S2 for the cooling water up to is provided. The flow path switching valve 5 is a valve that switches the flow of cooling water to a circulation path S4 and a circulation path S2, which will be described later. The electric pump 7 is a pump driven by electric power supplied from the battery 14. The heat storage tank 8 has a function of keeping the cooling water warm.

  Further, the heat storage system includes a circulation passage for flowing cooling water in parallel with the circulation passage S2, a circulation passage S3 from the branch point C4 to the oil cooler 4 in the cylinder block 3, and the branch point C5, and a flow path. A circulation passage S4 is provided from the switching valve 5 to the interior heating / cooling heater 6 and the branch point C2. The oil cooler 4 controls the temperature of the lubricating oil of the internal combustion engine 1 that flows in the cylinder block 3 using the thermal energy of the cooling water. In addition, the vehicle interior heating / cooling heater 6 uses the thermal energy of the cooling water to produce warm air or cold air for vehicle interior / cooling.

  The internal combustion engine 1 is also provided with an electronic control unit (hereinafter referred to as “ECU”) 20 for controlling each component of the heat storage system. In addition to the CPU, the ECU 20 includes a ROM, a RAM, and the like that store various programs and maps to be described later, and controls each component in accordance with the operating conditions of the internal combustion engine 1, the driver's request, and the like.

  Here, the accelerator opening sensor 15 is electrically connected to the ECU 20, and the ECU 20 receives a signal corresponding to the accelerator opening, and calculates the engine load required for the internal combustion engine 1 based on the signal. Further, the crank position sensor 16 is electrically connected to the ECU 20, and the ECU 20 receives a signal corresponding to the rotation angle of the crankshaft of the internal combustion engine 1, and the engine rotational speed of the internal combustion engine 1, the engine rotational speed and the gear. The vehicle speed or the like of the vehicle on which the internal combustion engine 1 is mounted is calculated from the ratio or the like. Further, a cooling water temperature sensor 12 for detecting the temperature of the cooling water supplied to the internal combustion engine 1 and a cooling water temperature sensor 13 for detecting the temperature of the cooling water near the outlet of the heat storage tank 8 are electrically connected to the ECU 20. It is connected to the. As a result, the ECU 20 detects the coolant temperature in the internal combustion engine 1 (hereinafter referred to as “engine coolant temperature”) and the coolant temperature near the outlet of the heat storage tank 8 (hereinafter referred to as “tank outlet coolant temperature”) from each sensor. ") Is detected.

  The ECU 20 is electrically connected to the flow path switching valve 5, the flow rate adjustment valve 17, and the battery 14. Thereby, the flow path switching valve 5 is operated and the flow path of the cooling water is switched by the command from the ECU 20, the opening degree of the flow rate adjusting valve 17 is adjusted, or the electric power is supplied to the electric pump 7. Be controlled.

  When the engine temperature is low, such as when the internal combustion engine 1 is started, the lubricating oil temperature of the cylinder head 2, the cylinder block 3, the oil cooler 4, etc. is low, and the friction with respect to the engine output increases. As a result, fuel consumption and emissions may be deteriorated. Therefore, in the heat storage system of the internal combustion engine 1 configured as described above, when the engine temperature is low, such as when the engine is started, the relatively high temperature cooling water stored in the heat storage tank 8 is circulated by the electric pump 7. By supplying to a part of the passages S2 and S1, the temperature of the cylinder head 2, the cylinder block 3, the oil cooler 4 and the like is raised. At this time, the supply of the cooling water to the radiator 9 is blocked by the flow path adjustment valve 17, and the supply of the cooling water to the vehicle interior cooling / heating heater 6 is blocked by the flow path switching valve 5.

  Here, when the engine temperature of the internal combustion engine 1 is increased by the heat storage system of the internal combustion engine 1, the ECU 20 performs a failure determination of the heat storage system. In the present embodiment, the failure determination of the heat storage system is performed based on the flow rate of the cooling water supplied to the internal combustion engine 1 through a part of the circulation passage S1 and the circulation passage S2. Specifically, when the cooling water flow rate is lower than the target flow rate, it is determined that the heat storage tank 8, the circulation passages S1, S2, etc. are damaged, the electric pump 7 is defective, or the like. When the ECU 20 determines that the heat storage system is in a failure state, the ECU 20 notifies the warning panel 21 of the failure, and the driver of the vehicle equipped with the internal combustion engine 1 is informed of the existence of the failure.

Here, estimation of the flow rate of the supply cooling water at the time of failure determination of the heat storage system will be described based on FIG. The horizontal axis in FIG. 2 represents the elapsed time after the cooling water supply start time by the electric pump 7 is t0, and the vertical axis represents the temperature of the cooling water flowing through the circulation passage. Each of the lines L1 and L2 in the figure is detected by the cooling water temperature sensor 13 when the relatively high temperature cooling water is stored in the heat storage tank 8 and the cooling water is supplied to the internal combustion engine 1. 6 shows the transition of the tank outlet coolant temperature and the engine coolant temperature detected by the coolant temperature sensor 12. Each of the lines L3 and L4 in the figure is detected by the cooling water temperature sensor 13 when the relatively low-temperature cooling water is stored in the heat storage tank 8 and the cooling water is supplied to the internal combustion engine 1. 6 shows the transition of the tank outlet coolant temperature and the engine coolant temperature detected by the coolant temperature sensor 12.

  In the case of the lines L1 and L2, that is, the estimation of the flow rate of the supplied cooling water when the relatively high temperature cooling water is stored in the heat storage tank 8 will be described. By starting the supply of the cooling water by the electric pump 7 at the supply start time t0, the tank outlet cooling water temperature and the engine cooling water temperature rise. When the heat storage tank 8 is used as a reference, the cooling water temperature sensor 12 is disposed farther (downstream) than the cooling water temperature sensor 13, so that the cooling water temperature detected by the cooling water temperature sensor 12 is greater. The rise is slow.

  Here, after the start of the supply of the cooling water by the electric pump 7, the time difference until the tank outlet cooling water temperature and the engine cooling water temperature each reach the temperature CT1 is T1. In this embodiment, the temperature CT1 is 5 degrees higher than the engine cooling water temperature at time t0, and the cooling water stored in the heat storage tank 8 is provided with the cooling water temperature sensors 12 and 13. It is a threshold value for detecting the arrival at a certain site by an increase in water temperature.

The time difference T1 in the detection of the cooling water temperature rise by the cooling water temperature sensors 12, 13 is the circulation path S1 between the part where the cooling water temperature sensor 12 is installed and the part where the cooling water temperature sensor 13 is installed. , S2 and the flow rate of the cooling water flowing therethrough. Therefore, the flow rate of the cooling water can be estimated based on the following equation.
(Cooling water flow rate) = (Volume of circulation passages S1 and S2 between the part where the cooling water temperature sensor 12 is installed and the part where the cooling water temperature sensor 13 is installed) / time difference T1 (Equation 1 )

  However, when the flow rate of the cooling water is estimated based on the temperature increase of the cooling water in this way, the degree of the cooling water temperature increase detected by the cooling water temperature sensors 12 and 13 is stored in the heat storage tank 8. Since it fluctuates depending on the cooling water temperature, it is difficult to accurately estimate the flow rate of the cooling water, and the accuracy of the failure determination of the heat storage system based on the cooling water flow rate is lowered.

  For example, in the case of lines L3 and L4, that is, when relatively low-temperature cooling water is stored in the heat storage tank 8, the flow rate of the cooling water flowing through the circulation passages S1 and S2 is actually the lines L1 and L2. Even with the same amount, as shown in FIG. 2, the time difference in detection of the cooling water temperature CT1 by the cooling water temperature sensors 12 and 13 is T2 longer than T1. This is because the degree of increase in the coolant temperature detected by the coolant temperature sensors 12 and 13 becomes moderate as the coolant temperature decreases. Therefore, when the flow rate of the cooling water is estimated based on the time difference T2 and the above equation (1), a smaller flow rate is estimated than when the flow rate is estimated based on the time difference T1. If the failure determination of the heat storage system is performed based on the reduced flow rate, even if the flow rate is actually normal, there is a possibility that the heat storage system is erroneously determined to be in a failure state due to the flow rate decrease.

  Therefore, in the failure determination of the heat storage system of the present embodiment, the failure determination control shown in FIG. 3 is performed in order to make a highly accurate determination. Hereinafter, the failure determination control shown in FIG. 3 will be described. Note that the failure determination control shown in FIG. 3 is a routine executed by the ECU 20.

  In S101, it is determined whether or not the electric pump 7 is being driven. That is, it is determined whether or not the cooling water stored in the heat storage tank 8 is supplied to the internal combustion engine 1 by the electric pump 7. If it is determined that the electric pump 7 is driven, the process proceeds to S102, and if it is determined that the electric pump 7 is not driven, the process of S101 is performed again.

In S102, a cooling water arrival time difference TA corresponding to the time differences T1 and T2 shown in FIG. 2 is detected. That is, the time difference TA when the coolant temperature detected by the coolant temperature sensors 12 and 13 reaches the temperature CT1 is detected. When the process of S102 ends, the process proceeds to S103.

  In S103, it is determined whether or not a predetermined time t3 has elapsed since the electric pump 7 started to start at t0. The predetermined time t3 is t3 shown in FIG. 2, and is a time until the tank outlet cooling water temperature rises by the supply of the cooling water by the electric pump 7 and the temperature rise is almost stabilized. The tank outlet cooling water temperature when the predetermined time t3 has passed is substantially the same as the temperature of the cooling water stored in the heat storage tank 8 when the supply of the cooling water by the electric pump 7 is started. It can be regarded as warm. If it is determined in S103 that the predetermined time t3 has elapsed, the process proceeds to S104. If it is determined that the predetermined time t3 has not elapsed, the process of S103 is performed again.

In S104, the coolant arrival time difference TA detected in S102 is corrected based on the tank outlet coolant temperature after the elapse of the predetermined time t3. Note that the correction of the cooling water arrival time difference TA is based on Equation 2 shown below.
Correction value TA = Detection value TA−α (Expression 2)
Α in Equation 2 is a correction amount, and the relationship between the correction amount α and the tank outlet coolant temperature after the elapse of the predetermined time t3 is shown in FIG. That is, the correction amount α increases as the tank outlet cooling water temperature decreases after a predetermined time has elapsed, and as a result, the corrected cooling water arrival time difference TA decreases. As shown in FIG. 2, even if the actual cooling water flow rate is the same, the cooling water arrival time difference TA becomes longer as the cooling water temperature stored in the heat storage tank 8 is lower. It is a thing. When the process of S104 ends, the process proceeds to S105.

  In S105, the flow rate FR of the cooling water supplied to the internal combustion engine 1 is estimated based on the cooling water arrival time difference TA corrected in S104 and Equation 1. When the process of S105 ends, the process proceeds to S106.

  In S106, a flow rate determination value FR0 is calculated. The flow rate determination value FR0 is a determination reference value used in S107, which will be described later, and is a flow rate of cooling water that can be supplied by the electric pump 7. The flow rate determination value FR0 varies depending on the coolant temperature at the start of coolant supply by the electric pump 7 (hereinafter referred to as “cooling water temperature initial value”). Therefore, as shown in FIG. 5, the flow rate determination value FR0 is set to be larger as the cooling water temperature initial value becomes higher. Further, the flow rate determination value FR0 varies depending on the outside air temperature around the internal combustion engine 1, the voltage remaining in the battery 14, and the like, and may be set based on these parameters. When the process of S106 ends, the process proceeds to S107.

  In S107, it is determined whether or not the cooling water flow rate FR estimated in S105 is smaller than the flow rate determination value FR0 calculated in S106. That is, it is determined whether or not the flow rate of the cooling water supplied to the internal combustion engine 1 is lower than the flow rate that should be originally supplied by the electric pump 7. When the cooling water flow rate FR is smaller than the flow rate determination value FR0, it means that the cooling water of the flow rate that should be supplied by the electric pump 7 is not supplied, and the process proceeds to S108. On the other hand, when the cooling water flow rate FR is equal to or higher than the flow rate determination value FR0, it means that the cooling water of the flow rate that should be originally supplied by the electric pump 7 is supplied. This control is terminated.

  In S108, in response to the determination result in S107, the ECU 20 determines that air is mixed into the electric pump 7 and the actual cooling water supply capacity of the electric pump 7 is reduced. When the process of S108 ends, the process proceeds to S109.

Here, mixing of air into the electric pump 7 causes a decrease in the cooling water capacity of the electric pump 7, but this is temporary and usually disappears as the driving time of the electric pump 7 elapses. . On the other hand, if the failure determination of the heat storage system by the ECU 20 is continued, the other components of the heat storage system (the heat storage tank 8 and the circulation passage S1,. There is a risk of misjudging that the damage is S2). Therefore, in S109, failure determination of the heat storage system by the ECU 20 is prohibited. When the process of S109 ends, the process proceeds to S110.

  In S110, it is determined whether or not the determination of air mixing into the electric pump 7 in S108 has been made a predetermined number of times continuously. The fact that the determination of air mixing into the electric pump 7 is continuously issued means that air continues to be mixed into the electric pump 7 while the cooling water supply capacity is kept low. is doing. Therefore, in such a case, it is preferable to forcibly exclude the air mixed in the electric pump 7. Therefore, if it is determined that the determination of air mixing into the electric pump 7 has been made a predetermined number of times, the process proceeds to S111, where air is mixed into the electric pump 7 from the ECU 20 to the panel 21. Send a warning to the effect. This makes it possible for the operator to forcibly remove the air mixed in the electric pump 7.

  Further, when it is determined that the determination of air mixing into the electric pump 7 has not been made continuously a predetermined number of times, this control is terminated. This predetermined number of times is set to an arbitrary value in consideration of the warning frequency to the operator and the reduction in the supply capacity of the electric pump 7.

  According to this control, the flow rate of the cooling water supplied to the internal combustion engine 1 can be estimated more accurately, and the failure determination of the heat storage system can be performed with higher accuracy by the flow rate. Furthermore, it is possible to eliminate as much as possible an erroneous determination in the failure determination due to air mixing inside the electric pump 7.

  A second embodiment of the internal combustion engine failure determination system according to the present invention will be described with reference to FIGS. FIG. 6 shows failure determination control for performing highly accurate determination in the failure determination of the heat storage system. The failure determination control shown in FIG. 6 is a routine executed by the ECU 20 in the internal combustion engine 1 and its heat storage system shown in FIG.

  In S201, as in S101 described above, it is determined whether or not the electric pump 7 is being driven. If it is determined that the electric pump 7 is driven, the process proceeds to S202. If it is determined that the electric pump 7 is not driven, the process of S201 is performed again.

  In S <b> 202, the cooling water temperature sensor 12 measures an increase rate TB of the cooling water temperature when the cooling water stored in the heat storage tank 8 by the electric pump 7 is supplied to the internal combustion engine 1. When the process of S202 ends, the process proceeds to S203.

  In S203, as in S103 described above, it is determined whether or not a predetermined time t3 has elapsed since the electric pump 7 started to start at t0. The times t0 and t3 are as shown in FIG. The tank outlet cooling water temperature when the predetermined time t3 has elapsed is considered to be substantially the same as the temperature of the cooling water that has been kept warm in the heat storage tank 8 when the supply of the cooling water by the electric pump 7 is started. be able to. If it is determined in S203 that the predetermined time t3 has elapsed, the process proceeds to S204. If it is determined that the predetermined time t3 has not elapsed, the process of S203 is performed again.

In S204, the increase rate determination value TB0 is calculated based on the tank outlet cooling water temperature detected by the cooling water temperature sensor 13. The increase rate determination value TB0 is a reference value for determination used in S205, which will be described later, and is a reference value for determining whether or not the engine temperature is appropriately increased by the heat storage system. Here, the rising rate of the cooling water at the portion where the cooling water temperature sensor 13 is installed is the cooling stored in the heat storage tank 8 when the cooling water supply is started by the electric pump 7 as shown in FIG. Varies with water temperature. Therefore, the tank outlet cooling water temperature detected by the cooling water temperature sensor 13 after the elapse of the predetermined time t3 is regarded as the temperature of the cooling water stored in the heat storage tank 8, and is used in S205 based on the cooling water temperature. It is possible to set the reference value for the determination to be a more appropriate value.

  Specifically, as the temperature of the cooling water stored in the heat storage tank 8 increases, the rate of increase in the tank outlet cooling water temperature detected by the cooling water temperature sensor 13 increases. Therefore, as shown in FIG. 7, the rate of increase rate determination value TB0 is increased as the tank outlet cooling water temperature increases after a predetermined time t3. When the process of S204 ends, the process proceeds to S205.

  In S205, it is determined whether or not the temperature increase rate TB measured in S202 is smaller than the increase rate determination value TB0 calculated in S204. Here, the fact that the temperature increase rate TB is smaller than the increase rate determination value TB0 means that the engine temperature does not increase according to the cooling water stored in the heat storage tank 8 by the heat storage system, and there is some abnormality in the heat storage system. Means there is. Therefore, if it is determined that the temperature increase rate TB is smaller than the increase rate determination value TB0, the process proceeds to S206, and the ECU 20 determines that the heat storage system is in a failure state and displays a failure of the heat storage system on the panel 21. On the other hand, if it is determined that the temperature increase rate TB is equal to or higher than the increase rate determination value TB0, the control is terminated because the heat storage system is not in a failure state.

  According to this control, it is possible to perform failure determination with higher accuracy by adjusting the reference value TB0 in failure determination of the heat storage system based on the cooling water temperature stored in the heat storage tank 8.

It is a figure showing the schematic structure of the thermal storage system of the internal combustion engine which concerns on the Example of this invention, and its failure determination system. In the failure determination system which concerns on the Example of this invention, it is a figure which shows the temperature transition of the cooling water which flows through the circulation path of a thermal storage system. It is a flowchart regarding the failure determination control performed in the failure determination system of the internal combustion engine which concerns on 1st Example of this invention. It is a figure which shows the relationship between the correction amount of the cooling water arrival time difference in the failure determination control shown in FIG. 3, and tank outlet cooling water temperature. It is a figure which shows the relationship between the flow volume determination value in the failure determination control shown in FIG. 3, and a cooling water temperature initial value. It is a flowchart regarding the failure determination control performed in the failure determination system of the internal combustion engine which concerns on 2nd Example of this invention. It is a figure which shows the relationship between the raise rate determination value and tank exit cooling water temperature in the failure determination control shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 .... Internal combustion engine 2 .... Cylinder head 3 .... Cylinder block 7 .... Electric pump 8 .... Thermal storage tank 9 .... Radiator 10 .... Mechanical pump 12 .... Cooling water temperature sensor 13 .... Cooling water temperature sensor 14 .... Battery 20 .... ECU
21... Panel S1, S2, S3, S4.

Claims (8)

A passage through which the heat medium circulates and is formed via an internal combustion engine, a heat storage tank that retains and stores part of the heat medium that circulates through the circulation passage, and a heat medium stored in the heat storage tank A heat storage system having a heat medium pump for supplying the heat to the circulation passage, and
A flow rate estimating means for estimating a flow rate of the heat medium flowing through the circulation path based on a temperature rise of the heat medium flowing through a predetermined portion of the circulation path when the heat medium is supplied to the circulation path by the heat medium pump;
Flow rate correction means for correcting the heat medium flow rate estimated by the flow rate estimation means based on the heat medium temperature in the heat storage tank when the heat medium is supplied to the circulation passage by the heat medium pump;
Failure determination means for determining whether or not the heat storage system is in a failure state based on the heat medium flow rate corrected by the flow rate correction means;
An internal combustion engine failure determination system comprising: The predetermined part is a first part of the circulation passage and a second part downstream of the first part,
First temperature detection means for detecting the temperature of the heat medium flowing through the first portion;
A second temperature detecting means for detecting the temperature of the heat medium flowing through the second part,
The flow rate estimating means includes a time when the heat medium temperature detected by the first temperature detecting means reaches a first predetermined temperature and the second temperature after the heat medium is supplied to the circulation passage by the heat medium pump. 2. The internal combustion engine according to claim 1, wherein the flow rate of the heat medium flowing through the circulation passage is estimated based on a time difference from a time when the heat medium temperature detected by the detection means reaches the second predetermined temperature. Failure judgment system. The first part is a part of the circulation passage in the vicinity of an outlet of the heat storage tank where the heat storage tank and the circulation passage are connected,
The internal combustion engine failure determination system according to claim 2, wherein the second part is a part of the circulation passage inside the internal combustion engine. The flow rate correction means increases the heat medium flow rate estimated by the flow rate estimation means as the heat medium temperature in the heat storage tank decreases when the heat medium is supplied to the circulation passage by the heat medium pump. The failure determination system for an internal combustion engine according to any one of claims 1 to 3, wherein the value is corrected to a value.   The heat medium temperature in the heat storage tank, which is a reference for correcting the heat medium flow rate by the flow rate correcting means, is the value when a predetermined time has elapsed since the heat medium was supplied to the circulation passage by the heat medium pump. 5. The internal combustion engine according to claim 1, wherein the internal combustion engine is set to a temperature of a heat medium flowing through a portion of the circulation passage in the vicinity of an outlet of the heat storage tank where the heat storage tank is connected to the circulation passage. Failure judgment system.   The failure determination means determines that air has entered the heat medium pump when the heat medium flow corrected by the flow correction means is less than a predetermined flow, and whether or not the heat storage system is in a failure state. 6. The internal combustion engine failure determination system according to claim 1, wherein the determination is interrupted.   The predetermined flow rate is at least an outside air temperature, an intake air temperature of the internal combustion engine, a heat medium temperature in the circulation passage when the internal combustion engine is stopped, and a remaining voltage of a battery that supplies power to the heat medium pump. The internal combustion engine failure determination system according to claim 6, wherein the internal combustion engine failure determination system is determined based on any of the above.   When the failure determination means determines that air is mixed in the heat medium pump, the air notifies the driver of the vehicle on which the internal combustion engine is mounted that air is mixed in the heat medium pump. The internal combustion engine failure determination system according to claim 6 or 7, further comprising a mixing notification means.

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