JP2009174387A - Cooling control device and cooling control method for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately estimate temperature of coolant in an internal combustion engine circulation cooling system in an internal combustion engine provided with an exhaust heat recovery apparatus. <P>SOLUTION: In this cooling control device, an exhaust heat recovery control part 530 determines whether exhaust heat recovery is executed or not, based on cooling water temperature Tw detected with a cooling water temperature sensor 300. A water temperature counter part 550 calculates estimation temperature Tcnt reflecting heating value of the engine. A correction calculation part 560 determines correction temperature ΔTcnt reflecting heat receive quantity of engine cooling water from exhaust gas via an exhaust heat recovery apparatus and calculates temperature estimation value Twcnt of engine cooling water according to sum of the estimation temperature Tcnt and the correction temperature ΔTcnt. The correction temperature ΔTcnt is set based on catalyst temperature estimation value Tctl# and on/off of exhaust heat recovery in a zone where cooling water temperature Tw is lower than determination temperature, and the temperature estimation value Twcnt is calculated with fixing the correction temperature ΔTcnt to zero in a zone where the cooling water temperature Tw is not lower than the determination temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cooling control device and a cooling control method for an internal combustion engine, and more particularly to a cooling control device and a cooling control method for an internal combustion engine in which an exhaust heat recovery device is disposed in an exhaust system.

  An exhaust heat recovery device is installed in an exhaust system of an automobile equipped with an internal combustion engine to recover heat from the exhaust gas of the internal combustion engine. For example, Japanese Patent Laid-Open No. 2007-46469 (Patent Document 1) describes an exhaust heat recovery device that is disposed in an exhaust pipe of an internal combustion engine and transports exhaust heat of exhaust gas to circulating cooling water of the internal combustion engine. ing. In the exhaust heat recovery device of Patent Document 1, it is described that a heat switch function that regulates the amount of heat transport from the exhaust gas to the cooling water is controlled according to the cooling water temperature of the internal combustion engine. Further, in Japanese Patent Application Laid-Open No. 2005-16477 (Patent Document 2), the catalyst heat generation amount increase control for increasing the heat generation amount in the catalytic converter through which exhaust gas passes is performed when the engine coolant temperature is lower than a predetermined value or air conditioning. It is described that it is executed when there is a request to increase the heating capacity of the apparatus. Thereby, it becomes possible to efficiently make up for the insufficient heating capacity by recovering more reaction heat of the catalyst with the engine cooling water.

  Japanese Patent Laying-Open No. 2005-117836 (Patent Document 3) arranges a power generation module made of a thermoelectric element in an exhaust pipe, heats the high temperature end side of the thermoelectric element with exhaust gas, and sets the low temperature end side to the engine. An exhaust heat energy recovery device that generates power by the Seebeck effect due to a temperature difference by cooling with cooling water is described. In the exhaust heat energy recovery device of Patent Document 1, when estimating the temperature at the high temperature end side and the low temperature end side from the cooling water temperature measured by the water temperature sensor and the exhaust gas temperature measured by the exhaust gas temperature sensor, respectively, It is described that the reliability is tested by cross-checking.

Further, according to Japanese Patent Laying-Open No. 2002-4932 (Patent Document 4), the warm-up counter is operated according to the engine coolant temperature calculated based on the operating state of the engine, and the counter value of the warm-up counter is set. Describes an abnormality diagnosis device for an engine system in which an abnormality determination of a thermostat is permitted based on the fact that is equal to or greater than a predetermined value. In this way, even when the chance of abnormality diagnosis is limited, such as when the engine is repeatedly operated and stopped, the abnormality determination of the thermostat based on the detection of the engine coolant temperature can be performed accurately and early. Can be performed.
JP 2007-46469 A Japanese Patent Laying-Open No. 2005-16477 JP-A-2005-117836 JP 2002-4932 A

  As described in Patent Document 4, it has been proposed to perform control and / or abnormality diagnosis of a cooling device for an internal combustion engine based on a temperature estimation value such as a counter value. However, when the exhaust heat recovery device described in Patent Documents 1 and 2 is mounted on the exhaust system of the internal combustion engine, a circulating cooling system by exhaust heat of the exhaust gas of the internal combustion engine via the exhaust heat recovery device Unless the estimated temperature value is calculated by reflecting the amount of heat received by the cooling medium (typically, cooling water), there is a possibility that the cooling control and / or abnormality diagnosis may be hindered.

  The present invention has been made to solve such problems, and an object of the present invention is to reduce the refrigerant temperature of the circulating cooling system of the internal combustion engine in the internal combustion engine provided with the exhaust heat recovery device. It is simple and accurate estimation.

  An internal combustion engine cooling control device according to the present invention is an internal combustion engine cooling control device in which an exhaust pipe is provided with a catalyst and an exhaust heat recovery device, the exhaust heat recovery control unit, a temperature sensor, a refrigerant temperature estimation unit, Is provided. The exhaust heat recovery control unit determines whether or not heat exchange between the exhaust gas passing through the exhaust pipe by the exhaust heat recovery device and the refrigerant is necessary based on the temperature of the refrigerant in the circulation cooling system of the internal combustion engine. The temperature sensor detects the temperature of the refrigerant. The refrigerant temperature estimation unit calculates an estimated temperature of the refrigerant based on the operating state of the internal combustion engine. Furthermore, in the first temperature region where the temperature of the refrigerant is lower than the reference temperature, the refrigerant temperature estimation unit calculates the estimated temperature value with a correction calculation that reflects the amount of heat received by the refrigerant via the exhaust heat recovery device. In the second temperature region in which the temperature of the refrigerant is equal to or higher than the reference temperature, the estimated temperature value is calculated without performing the correction calculation.

  Preferably, in the first temperature range, the refrigerant temperature estimation unit is configured to perform relative temperature estimation values corresponding to the same operation state when heat exchange is performed by the exhaust heat recovery device, compared to when heat exchange is not performed. The correction calculation is executed so that it is calculated as high as possible.

  Preferably, the cooling control device further includes a catalyst temperature estimation unit that estimates the temperature of the catalyst based on the operating state of the internal combustion engine. The refrigerant temperature estimation unit includes first and second estimation calculation units. The first estimation calculation unit calculates a first estimated value reflecting the heat generation amount of the internal combustion engine based on the operating state parameter value of the internal combustion engine. The second estimation calculation unit calculates a second estimated value reflecting the amount of heat received by the refrigerant from the exhaust system of the internal combustion engine based on the estimated temperature value of the catalyst and whether or not heat exchange is performed, Based on the sum of the first and second estimated values, a temperature estimated value is calculated. Furthermore, the second estimation calculation unit fixes the second estimation value to substantially 0 in the second temperature region where the correction calculation is not executed.

  The cooling control method for an internal combustion engine according to the present invention is a cooling control method for an internal combustion engine in which an exhaust pipe is provided with a catalyst and an exhaust heat recovery device, and the exhaust gas passing through the exhaust pipe and the circulation of the internal combustion engine by the exhaust heat recovery device. The heat exchange with the refrigerant in the cooling system is executed or not executed based on the output of the temperature sensor that detects the temperature of the refrigerant. The cooling control method includes a step of calculating a first estimated value that reflects the amount of heat generated by the internal combustion engine based on an operating state of the internal combustion engine, and a second state that reflects the amount of heat received by the refrigerant from the exhaust system of the internal combustion engine. Calculating an estimated value; and calculating a refrigerant temperature estimated value based on a sum of the first and second estimated values. Then, in the step of calculating the second estimated value, the estimated value of the second estimated value is fixed to almost zero in the region where the temperature of the refrigerant is equal to or higher than the reference temperature.

  Preferably, in the step of calculating the second estimated value, in the region where the temperature of the refrigerant is lower than the reference temperature, the heat exchange by the exhaust heat recovery unit is performed under the same condition as compared with the non-execution of heat exchange. The corresponding second estimated value is calculated relatively high.

  Preferably, the cooling control device further includes an abnormality diagnosis unit that detects an abnormality of the temperature sensor by comparing a temperature estimated value by the refrigerant temperature estimation unit and a detection value by the temperature sensor. Alternatively, the cooling control method further includes a step of detecting an abnormality of the temperature sensor based on a comparison between the calculated estimated temperature value and the detected value of the temperature sensor.

  According to the cooling control device and the cooling control method for an internal combustion engine, in the region where the refrigerant temperature of the circulating cooling system is low, the correction calculation of the estimated temperature value reflecting the amount of heat received by the refrigerant from the exhaust gas via the exhaust heat recovery device On the other hand, in the region where the refrigerant temperature is equal to or higher than the reference temperature, the estimated temperature value can be calculated without executing the correction calculation, reflecting that the influence of the heat received from the exhaust gas by the exhaust heat recovery device is small. Thereby, the estimated value of the refrigerant temperature can be calculated easily and accurately by appropriately reflecting the influence of the exhaust heat recovery by the exhaust heat recovery device.

  Furthermore, the accuracy of abnormality diagnosis of the temperature sensor for detecting the refrigerant temperature can be improved using the estimated temperature value.

  According to this invention, the refrigerant temperature of the circulating cooling system of the internal combustion engine provided with the exhaust heat recovery device can be accurately estimated.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

  FIG. 1 is a block diagram showing a configuration of an engine circulation cooling system controlled by an internal combustion engine cooling control apparatus according to an embodiment of the present invention.

  Referring to FIG. 1, engine 100 is an internal combustion engine provided with a cooling passage (not shown) made of a refrigerant. Since water is typically used as the refrigerant of engine 100, the refrigerant is hereinafter also referred to as engine cooling water or simply cooling water, but it is also possible to use materials other than water as the refrigerant. Is described in a confirming manner.

  Engine 100 is provided with a water pump 120 for circulating the refrigerant in the cooling device. Water pump 120 may be an electric pump or may be a mechanical pump driven by the rotational force of engine 100. The cooling water piping group 500 includes a cooling water circulation path 500 a for allowing cooling water output from the engine 100 to flow to the radiator 210 and a cooling water circulation path 500 b for allowing the heater 200 to flow by the operation of the water pump 120. It arrange | positions so that it may form in parallel.

  A radiator 210 and a thermostat 220 are provided in the cooling water circulation path 500a. The thermostat 220 opens and closes according to the temperature of the cooling water at the arrangement site. In the cooling water circulation path 500a, when the thermostat 220 is closed (when the engine is cold), a cooling water path 515 is formed from the cooling water outlet of the engine 100 to the water pump 120 by bypassing the radiator 210 by the bypass pipe 510. Is done. On the other hand, when the temperature of the cooling water rises and the thermostat 220 opens (that is, when the engine is warm), the cooling water in the cooling water circulation path 500a passes through the radiator 100 from the cooling water outlet of the engine 100 without passing through the bypass pipe 510. The cooling water path 525 that passes through 210 and reaches the water pump 120 is circulated. The radiator 210 has an air cooling mechanism (not shown), and cools the circulating cooling water by heat exchange in the air cooling mechanism.

  Cooling water circulation path 500b includes a cooling water path 505 that flows from the cooling water outlet of engine 100 through heater 200 and exhaust heat recovery device 150 to water pump 120. The heater 200 is provided as a heating heat exchanger, and performs heating using the cooling water flowing through the cooling water circulation path 500b as a heat source. That is, as the cooling water circulates in the cooling water circulation path 500b by the operation of the water pump 120, the air heated by heat exchange with the cooling water (hot water) is sent into the vehicle interior by a fan (not shown).

  The heater 200 is shown as a representative example of a device that operates using the heat quantity of cooling water. Devices other than the heater 200 may be provided in the cooling water circulation path 500b instead of the heater 200 or in addition to the heater 200.

  The exhaust heat recovery unit 150 is provided in the exhaust pipe 110 of the engine 100 so that exhaust heat recovery can be performed by exchanging heat between the cooling water flowing through the cooling water circulation path 500b and the exhaust gas from the engine 100. It is configured. The exhaust heat recovery device 150 is provided with an exhaust control valve 160 as a switching mechanism for executing or not performing exhaust heat recovery.

Further, the exhaust pipe 110 is provided with a catalyst 140 (typically a three-way catalytic converter) for purifying the exhaust gas. The catalyst 140 is provided with a temperature sensor 142 for detecting the catalyst bed temperature.

  Cooling water temperature sensor 300 for detecting the temperature of the cooling water is provided at any location in the circulating cooling system of engine 100 configured as described above. For example, as shown in FIG. 1, the cooling water temperature sensor 300 is disposed at the outlet of the cooling water from the engine 100, but the arrangement location is not limited thereto.

  A control device 310 constituted by an ECU (electronic control unit) corresponds to the cooling control device for an internal combustion engine according to the embodiment of the present invention, and follows the cooling control method for the internal combustion engine according to the embodiment of the present invention. Run the program. The control device 310 controls the opening / closing of the exhaust control valve 160 according to the cooling water temperature Tw detected by the cooling water temperature sensor 300. Further, the estimated temperature of the engine coolant is calculated according to a method described in detail below.

  Here, a schematic configuration and control of the exhaust heat recovery unit 150 will be described with reference to FIGS. 2 and 3.

  Referring to FIG. 2, actuator 165 opens and closes exhaust control valve 160 in accordance with a control command from ECU 310. The actuator 165 can have any configuration such as one using electromagnetic force or hydraulic pressure. When the exhaust control valve 160 is closed in response to a control command (close command) from the ECU 310, the exhaust gas from the engine 100 can exchange heat with the refrigerant in the cooling water path 152 included in the cooling water circulation path 500b. The heat recovery path 156 flows. Thereby, heat exchange is performed between the exhaust gas and the cooling water in the cooling water circulation path 500b, and the temperature of the engine cooling water can be quickly raised by heat recovery of the exhaust gas.

  On the other hand, when the exhaust control valve 160 is opened in response to the control command (open command) from the ECU 310, the exhaust gas from the engine 100 passes through the bypass path 158 (dotted line) that bypasses the heat recovery path 156 shown by the solid line. To be discharged. At this time, since heat exchange between the exhaust gas and the cooling water is hardly performed, heat recovery as when the exhaust control valve 160 is closed is stopped.

  As shown in FIG. 3, the exhaust heat recovery by the exhaust heat recovery device 150 is controlled according to the comparison between the cooling water temperature Tw detected by the cooling water temperature sensor 300 and the determination value T1. Specifically, when Tw <T1, the exhaust control valve 160 shown in FIG. 2 is closed and exhaust heat recovery is executed (turned on). On the other hand, when Tw ≧ T1, the exhaust control is performed. The valve 160 is opened and exhaust heat recovery is not performed (off).

  Next, the temperature estimation of the engine coolant in the internal combustion engine cooling control according to the embodiment of the present invention will be described in detail.

  FIG. 4 is a functional block diagram illustrating engine coolant temperature estimation according to the embodiment of the present invention. Each functional block shown in FIG. 4 may be configured by a circuit (hardware) in ECU 310 having a function corresponding to the block, or ECU 310 executes software processing according to a preset program. The function may be realized.

  Referring to FIG. 4, exhaust heat recovery control section 530 opens / closes exhaust control valve 160, that is, turns on / off exhaust heat recovery, based on cooling water temperature Tw detected by cooling water temperature sensor 300. Control according to 3.

  Based on the catalyst bed temperature detected by the temperature sensor 142 (FIG. 1) and a parameter value (engine state value) indicating the operating state of the engine 100, the catalyst temperature estimating unit 540 is a temperature estimated value Tctl # (hereinafter referred to as the catalyst 140). The estimated catalyst temperature) is calculated. As the engine state value, an intake air temperature (outside air temperature), an intake air amount, a signal indicating the presence or absence of fuel cut (F / C), and the like are used. Alternatively, the catalyst temperature may be estimated by further reflecting the coolant temperature Tw by the coolant temperature sensor 300. Note that the calculation of the catalyst temperature estimated value Tctl # by the catalyst temperature estimating unit 540 is not limited to the above example, and a known method can be applied as appropriate. For example, the catalyst temperature estimated value Tctl # may be calculated only by the estimation calculation based on the engine state value and the heat capacity of the catalyst 140 without using the catalyst bed temperature.

  The water temperature counter unit 550 calculates an estimated temperature Tcnt of engine cooling water based on the engine state value. For example, the water temperature counter unit 550 compares the cooling water temperature Tw and the intake air temperature when starting the engine, and sets the lower temperature to the initial value of the estimated temperature Tcnt. Then, after engine 100 is started, estimated temperature Tcnt is sequentially updated according to the integration of count values set according to the intake air amount and intake air temperature of the engine state values.

  The correction calculation unit 560 obtains a correction temperature ΔTcnt that reflects the amount of heat received from the engine cooling water from the exhaust gas via the exhaust heat recovery unit 150. Correction calculation unit 560 includes an exhaust heat effect estimation unit 570, a correction temperature switching unit 572, and an addition unit 574.

  Exhaust heat influence estimation unit 570 calculates correction temperature ΔTcnt based on catalyst temperature estimation value Tctl # from catalyst temperature estimation unit 540 and on / off of exhaust heat recovery by exhaust heat recovery control unit 530.

  For example, as shown in FIG. 5, exhaust heat effect estimation unit 570 fixes ΔTcnt = 0 in a region where estimated catalyst temperature value Tctl # is equal to or lower than a predetermined temperature T0 (for example, about 600 ° C.). On the other hand, in the region of Tctl #> T0, exhaust heat effect estimation unit 570 responds to estimated catalyst temperature value Tctl # according to maps 610 and 620 in which the correspondence relationship between estimated catalyst temperature value Tctl # and corrected temperature ΔTcnt is preset. The correction temperature ΔTcnt is calculated.

  At this time, the exhaust heat influence estimation unit 570 calculates the correction temperature ΔTcnt according to the map 610 when the exhaust heat recovery is on (during execution), while the exhaust heat recovery is off (when not executed). The correction temperature ΔTcnt is configured to be calculated according to the map 620. In map 610, correction temperature ΔTcnt is set larger than map 620 for the same estimated catalyst temperature value Tctl #.

  Based on the cooling water temperature Tw detected by the cooling water temperature sensor 300, the correction temperature switching unit 572 adds the correction temperature ΔTcnt calculated by the exhaust heat effect estimation unit 570 in a temperature region where Tw is lower than the reference temperature Tth. To part 574. On the other hand, corrected temperature switching unit 572 transmits ΔTcnt = 0 to adding unit 574 in the temperature range of Tw ≧ Tth.

  Adder 574 calculates engine coolant temperature estimated value Twcnt according to the sum of corrected temperature ΔTcnt transmitted from corrected temperature switching unit 572 and estimated temperature Tcnt calculated by water temperature counter 550.

  The temperature estimated value Twcnt calculated in this way is appropriately used for engine cooling control and / or abnormality diagnosis. Typically, abnormality diagnosis unit 600 diagnoses abnormality of cooling water temperature sensor 300 based on estimated temperature value Twcnt. For example, the abnormality diagnosis unit 600 determines whether or not the cooling water temperature sensor 300 is based on a comparison between the cooling water temperature Tw, which is a detection value of the cooling water temperature sensor 300, and the estimated temperature value Twcnt. Is detected and the abnormality flag FLR is turned on.

  In FIG. 4, the estimated temperature Tcnt and the water temperature counter unit 550 correspond to the “first estimated value” and the “first estimated calculation unit”, respectively, and the correction temperature ΔTcnt and the correction calculation unit 560 correspond to the “second estimation value”. Corresponds to the “estimated value” and “second estimated calculation unit”. The water temperature counter unit 550 and the correction calculation unit 560 constitute a “refrigerant temperature estimation unit”.

  Next, a control processing procedure for realizing the engine coolant temperature estimation in the cooling control of the internal combustion engine according to the embodiment of the present invention by software processing will be described with reference to FIG. For example, a program for executing the control processing procedure shown in the flowchart of FIG. 6 is stored in advance in a storage area (not shown) in ECU 310 and executed at a predetermined cycle by a CPU (Central Processing Unit) (not shown) in ECU 310. Thus, the temperature estimation of the engine cooling water according to the functional block diagram shown in FIG. 4 can be executed.

  Referring to FIG. 6, in step S100, ECU 310 executes a water temperature counter process that reflects the amount of heat generated in engine 100, and calculates estimated temperature Tcnt corresponding to the “first estimated value”. That is, the process in step S100 corresponds to the function of the water temperature counter unit 550 shown in FIG.

  In step S110, ECU 310 compares current coolant temperature Tw (detected value by coolant temperature sensor 300) with reference temperature Tth. In the temperature range of Tw <Tth (when YES is determined in S110), ECU 310 further determines in step S120 whether exhaust heat recovery is turned on (executed). This determination can be performed based on the output of the exhaust heat recovery control unit 530 in FIG.

  When exhaust heat recovery is ON (YES in S120), ECU 310 calculates correction temperature ΔTcnt by referring to map 610 based on estimated catalyst temperature Tctl # in step S130. On the other hand, when exhaust heat recovery is OFF (NO in S120), ECU 310 calculates correction temperature ΔTcnt by referring to map 620 based on catalyst temperature estimated value Tctl # in step S140.

  On the other hand, ECU 310 fixes correction temperature ΔTcnt = 0 at step S150 in the temperature range of cooling water temperature Tw ≧ Tth (when NO is determined in S110). That is, the correction temperature ΔTcnt corresponding to the “second estimated value” is set through steps S130 to S150.

  Note that the processing in steps S120 to S140 corresponds to the processing of the exhaust heat effect estimation unit 570 shown in FIG. 4, and the determination in step S110 corresponds to the function of switching the correction temperature ΔTcnt by the correction temperature switching unit 572.

  Then, in step S160, ECU 310 determines the engine coolant according to the sum of estimated temperature Tcnt calculated in step S100 and correction temperature ΔTcnt set in any of steps S130 to S150, that is, according to the following equation (1). The estimated temperature value Twcnt is calculated.

Twcnt = Tcnt + ΔTcnt (1)
Further, in step S170, ECU 310 performs an abnormality detection process for cooling water temperature sensor 300 based on a comparison between estimated temperature value Twcnt obtained in step S160 and cooling water temperature Tw. That is, the determination in step S170 corresponds to the function of the abnormality diagnosis unit 600 in FIG. Thereby, the abnormality determination of the coolant temperature sensor 300 can be executed with high accuracy.

  As described above, according to the engine cooling water temperature estimation according to the embodiment of the present invention, the estimated temperature Tcnt reflecting the calorific value of the engine 100 and the engine from the exhaust gas via the exhaust heat recovery device 150. The estimated temperature Twcnt of the engine coolant can be calculated based on the sum of the correction temperature ΔTcnt set by the correction calculation reflecting the amount of heat received by the coolant.

  In particular, in a region where the temperature Tw of the engine cooling water that is the refrigerant of the circulating cooling system of the engine 100 is lower than the reference temperature Tth, the temperature reflecting the amount of heat received from the engine cooling water from the exhaust gas via the exhaust heat recovery device 150. While ΔTcnt is set by the correction calculation of the estimated value, ΔTcnt = 0 in the region where the cooling water temperature Tw is equal to or higher than the reference temperature Tth, reflecting that the influence of the heat received from the exhaust gas by the exhaust heat recovery device 150 is small. It is possible to calculate the estimated temperature value (ie, the correction calculation is not executed).

  Thereby, the estimated temperature value of the engine coolant (refrigerant) can be calculated easily and accurately by appropriately reflecting the influence of the exhaust heat recovery by the exhaust heat recovery unit 150. The reference temperature Tth corresponds to a temperature at which the influence of exhaust heat recovery on the temperature of engine cooling water can be ignored based on analysis of a general traveling pattern or based on experimental results. For example, Tth = 75 ° C. can be set.

  In particular, the reference temperature Tth is set to a lower temperature side than the determination value T1 for determining execution / non-execution of exhaust heat recovery, so that ΔTcnt = 0 is set even when exhaust heat recovery is executed. Therefore, it is possible to perform highly accurate estimation as compared with the case where the cooling water temperature is estimated by paying attention only to execution / non-execution of exhaust heat recovery.

  It should be noted that the configuration of the circulating cooling system of engine 100 shown in FIG. 1 is merely an example, and the application of the present invention is not limited to such a configuration. That is, the present invention can be commonly applied to a cooling control system for an internal combustion engine in which an exhaust heat recovery device for increasing the temperature of engine cooling water is provided in the exhaust system.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a block diagram which shows the structure of the circulating cooling system of the engine controlled by the cooling control apparatus of the internal combustion engine by embodiment of this invention. FIG. 2 is a conceptual diagram illustrating a schematic configuration and an operation of the exhaust heat recovery unit illustrated in FIG. 1. It is a conceptual diagram explaining control of exhaust heat recovery by the exhaust heat recovery device shown in FIG. It is a functional block diagram explaining the temperature estimation of the engine cooling water in the cooling control of the internal combustion engine according to the embodiment of the present invention. It is a conceptual diagram which shows the relationship between catalyst estimated temperature and correction | amendment temperature. It is a flowchart which shows the control processing procedure for implement | achieving cooling control of the internal combustion engine by embodiment of this invention by software processing.

Explanation of symbols

  100 Engine, 110 Exhaust pipe, 120 Water pump, 140 Catalyst, 142 Temperature sensor (Catalyst bed temperature), 150 Exhaust heat recovery unit, 152 Cooling water passage (inside exhaust heat recovery unit), 156 Heat recovery route, 158 Bypass route, 160 Exhaust control valve, 165 actuator (exhaust control valve), 200 heater, 210 radiator, 220 thermostat, 300 cooling water temperature sensor, 310 control unit (ECU), 500 cooling water piping group, 500a, 500b cooling water circulation path, 505, 515 525 Cooling water path, 510 Bypass piping, 530 Exhaust heat recovery control section, 540 Catalyst temperature estimation section, 550 Water temperature counter section, 560 Correction calculation section, 570 Exhaust heat influence estimation section, 572 Correction temperature switching section, 574 Addition section, 600 Abnormality diagnosis part, 610 map (When exhaust heat recovery is on), 620 map (when exhaust heat recovery is off), FLR abnormality flag (cooling water temperature sensor), T0 predetermined temperature (catalyst temperature), T1 judgment value (exhaust heat recovery on / off), Tcnt estimated temperature (Reflecting engine heat generation), Tctl # estimated catalyst temperature, Tth reference temperature (necessary for correction calculation), Tw cooling water temperature (sensor detection value), Twcnt temperature estimated value (engine refrigerant), ΔTcnt corrected temperature (reflecting exhaust heat recovery) ).

Claims (7)

A cooling control device for an internal combustion engine in which a catalyst and an exhaust heat recovery device are provided in an exhaust pipe,
An exhaust heat recovery control unit that determines whether or not heat exchange between the exhaust gas passing through the exhaust pipe by the exhaust heat recovery device and the refrigerant is necessary based on the temperature of the refrigerant in the circulation cooling system of the internal combustion engine; ,
A temperature sensor for detecting the temperature of the refrigerant;
A refrigerant temperature estimating unit that calculates an estimated temperature value of the refrigerant based on an operating state of the internal combustion engine,
The refrigerant temperature estimation unit calculates the temperature estimation value with a correction operation that reflects the amount of heat received by the refrigerant via the exhaust heat recovery device in a first temperature region where the temperature of the refrigerant is lower than a reference temperature. On the other hand, in the second temperature region in which the temperature of the refrigerant is equal to or higher than the reference temperature, the internal combustion engine cooling control device calculates the temperature estimated value without executing the correction calculation.   In the first temperature range, the refrigerant temperature estimation unit is configured to perform the heat exchange by the exhaust heat recovery unit when the temperature corresponding to the same operation state as compared to when the heat exchange is not performed. The cooling control apparatus for an internal combustion engine according to claim 1, wherein the correction calculation is executed so as to calculate an estimated value relatively high. A catalyst temperature estimating unit for estimating the temperature of the catalyst based on the operating state of the internal combustion engine;
The refrigerant temperature estimator is
A first estimation calculation unit that calculates a first estimated value reflecting the amount of heat generated by the internal combustion engine based on an operating state parameter value of the internal combustion engine;
Based on the estimated temperature value of the catalyst and the execution or non-execution of the heat exchange, a second estimated value reflecting the amount of heat received by the refrigerant from the exhaust system of the internal combustion engine is calculated, and the first and A second estimation calculation unit that calculates the temperature estimation value based on the sum of the second estimation values;
The cooling control for an internal combustion engine according to claim 1 or 2, wherein the second estimation calculation unit fixes the second estimation value to substantially zero in the second temperature region in which the correction calculation is not executed. apparatus.   The abnormality diagnosis part which detects the abnormality of the said temperature sensor by the comparison with the said temperature estimated value by the said refrigerant | coolant temperature estimation part, and the detected value by the said temperature sensor, The any one of Claim 1 to 3 further provided. The internal combustion engine cooling control apparatus. A cooling control method for an internal combustion engine in which an exhaust pipe is provided with a catalyst and an exhaust heat recovery device,
The heat exchange between the exhaust gas passing through the exhaust pipe by the exhaust heat recovery device and the refrigerant in the circulating cooling system of the internal combustion engine is executed or not executed based on the output of a temperature sensor that detects the temperature of the refrigerant. And
Calculating a first estimated value reflecting the amount of heat generated by the internal combustion engine based on the operating state of the internal combustion engine;
Calculating a second estimated value reflecting the amount of heat received by the refrigerant from the exhaust system of the internal combustion engine;
Calculating a temperature estimated value of the refrigerant based on a sum of the first and second estimated values;
The step of calculating the second estimated value is a cooling control method for an internal combustion engine, wherein the estimated value of the second estimated value is fixed to approximately 0 in a region where the temperature of the refrigerant is equal to or higher than a reference temperature.   In the step of calculating the second estimated value, in the region where the temperature of the refrigerant is lower than the reference temperature, when performing the heat exchange by the exhaust heat recovery device, compared to when not performing the heat exchange, 6. The cooling control method for an internal combustion engine according to claim 5, wherein the second estimated value corresponding to the same condition is calculated to be relatively high.   The internal combustion engine cooling control method according to claim 5, further comprising a step of detecting an abnormality of the temperature sensor based on a comparison between the calculated estimated temperature value and a detected value of the temperature sensor.

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