JP2018013043A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of reducing the possibility of fuel economy deteriorating by enabling a fuel injection quantity to be set appropriately according to a peripheral temperature of a combustion chamber, such as a wall temperature, while using a control method for a conventional internal combustion engine.SOLUTION: A control device includes a temperature sensor provided at a specific place in the periphery of a combustion chamber for detecting a peripheral temperature of the combustion chamber, which is the temperature of the specific place, a fuel control part for controlling a quantity of fuel injected and supplied to an internal combustion engine based on a water temperature in the periphery of an outlet part, which is the temperature of cooling water passing through the vicinity of the outlet part, and a water temperature conversion part. The water temperature conversion part is configured so as to convert the peripheral temperature of the combustion chamber detected by the temperature sensor after the start of the internal combustion engine to the water temperature in the periphery of the outlet part used by the fuel control part using an acquired conversion coefficient.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for a water-cooled internal combustion engine.

  In a typical water-cooled internal combustion engine, cooling water is circulated through a circulation path including a cooling water passage including a water jacket provided around a combustion chamber of the main body and a device such as a radiator. The cooling water circulating through the circulation path is warmed by taking away the heat generated in the main body, sent to the radiator, cooled by the outside air in the radiator, and returned to the main body again.

  In the prior art, the temperature of the cooling water detected by a water temperature sensor (referred to as “exit water temperature sensor”) disposed at the outlet (referred to as “exit part”) of a water jacket provided in the main body is determined. Detect as cooling water temperature. The ECU adjusts the flow rate of the cooling water passing through the radiator by controlling the flow rate control valve for adjusting the flow rate of the cooling water in the radiator so that the detected cooling water temperature becomes the target temperature (for example, , See Patent Document 1).

JP 2006-105093 A

  In the prior art, as the flow rate of the cooling water passing through the radiator changes, the flow rate of the cooling water circulating in the circulation path also changes so as to increase or decrease. When the flow rate of the circulating cooling water decreases, the heat transfer rate directly transmitted from the combustion chamber wall surface to the cooling water decreases, so that the amount of cooling water received from the combustion chamber wall surface decreases, In addition, the conductivity of the heat indirectly transmitted from the combustion chamber wall surface to the main body outlet via the cooling water is also lowered.

  As a result, the amount of heat generated in the combustion chamber cannot be quickly reflected in the coolant temperature of the cooling water at the outlet, and even if the wall temperature of the combustion chamber is high, the coolant temperature of the outlet (the temperature of the outlet water temperature sensor) A situation occurs where the (detected temperature) is low.

  Thus, when the internal combustion engine is controlled based on the temperature detected by the outlet water temperature sensor (specifically, control of the amount of fuel injected and supplied to the internal combustion engine), the combustion chamber and the surrounding temperature are controlled. The fuel injection amount to be determined becomes excessive, and the air-fuel ratio of the air-fuel mixture supplied to the engine becomes excessively rich. As a result, fuel consumption is deteriorated.

  On the other hand, it is conceivable to arrange a temperature sensor around the combustion chamber of the cooling water passage. However, the fuel injection control of the internal combustion engine, which is performed based on the temperature detected by the conventional outlet water temperature sensor, is performed based on the temperature detected by the outlet water temperature sensor. There is a problem that it is difficult to use the detection value of the sensor as it is for the control of a conventional internal combustion engine.

  The present invention has been made to address the above-described problems. That is, one of the objects of the present invention is to make it possible to appropriately set the fuel injection amount according to the ambient temperature of the combustion chamber, for example, the wall temperature, while using the conventional control method of the internal combustion engine. Thus, an object of the present invention is to provide a control device for an internal combustion engine (hereinafter also referred to as “the device of the present invention”) that can reduce the possibility of deterioration of fuel consumption.

The device of the present invention is a cooling water passage in which one end portion constitutes an inlet portion to the main body (40) of the cooling water internal combustion engine (10) and the other end portion constitutes an outlet portion from the main body of the internal combustion engine. A control device for an internal combustion engine comprising a cooling water passage in the main body of the internal combustion engine, through which the cooling water for passing around the combustion chamber of the internal combustion engine and cooling the periphery of the combustion chamber flows.
A temperature sensor (S) that is provided in a specific part around the combustion chamber and detects a combustion chamber peripheral temperature (Tn) that is the temperature of the specific part;
A fuel control unit (80) for controlling the amount of fuel injected and supplied to the internal combustion engine on the basis of an outlet portion peripheral water temperature (Twn) which is a temperature of cooling water passing near the outlet portion (position Q);
With
A combination of a starting temperature (Tsta) which is the temperature around the combustion chamber at the time of starting the internal combustion engine, an engine speed (NE) after starting the internal combustion engine, and an engine load (TQ) after starting the internal combustion engine A storage unit (83) that stores a conversion coefficient that defines the relationship between the combustion chamber ambient temperature (Tn) and the outlet ambient water temperature (Tw) after startup of the internal combustion engine in the form of a lookup table. When,
Applying the starting temperature detected by the temperature sensor when starting the internal combustion engine, the engine speed after starting the internal combustion engine and the engine load after starting the internal combustion engine to the look-up table, the conversion coefficient ( (αn or βm) (step 810, step 824, step 836 or step 846 in FIG. 8), a conversion coefficient acquisition unit (81);
A combustion chamber ambient temperature detected by the temperature sensor after the internal combustion engine is started is converted into the outlet ambient water temperature used by the fuel control unit using the acquired conversion coefficient (steps 814, 826, Step 838 and Step 848) a water temperature converter (81).

  According to this, a temperature sensor is provided in the specific site | part of a combustion chamber periphery, and detects the combustion chamber ambient temperature which is the temperature of the specific site. Then, the detected temperature (combustion chamber ambient temperature) of the temperature sensor is converted into the outlet ambient temperature used by the fuel control unit in accordance with the relationship between the temperature sensor detected in advance and the temperature detected by the outlet water temperature sensor. . As a result, it is possible to appropriately set the fuel injection amount in accordance with the temperature around the combustion chamber, for example, the wall temperature, while using the conventional control method of the internal combustion engine, so that the fuel consumption is improved. The possibility of getting worse can be reduced.

  In the above description, in order to help the understanding of the invention, the reference numerals used in the embodiments are attached to the configuration of the invention corresponding to the embodiments in parentheses, but each component of the invention is represented by the reference numerals. It is not limited to the defined embodiments. Other objects, other features and attendant advantages of the present invention will be readily understood from the description of the embodiments of the present invention described with reference to the following drawings.

FIG. 1 is a schematic view of an internal combustion engine to which an internal combustion engine control apparatus according to a first embodiment of the present invention is applied. FIG. 2 is a schematic diagram of a cooling device provided in the internal combustion engine shown in FIG. FIG. 3 is a graph showing temperature changes of the combustion chamber wall temperature and the outlet water temperature with respect to time in the warm-up process control and the control after the warm-up operation. FIG. 4 is a graph in which a plurality of extraction points (engine rotation speed [rpm], engine load [Nm]) are plotted on the coordinates of the horizontal axis: engine rotation speed [rpm] and the vertical axis: engine load [Nm]. . FIG. 5 is a graph in which {(Tn−Tsta) / (Tw−Tsta)} is plotted against “Tn−Tsta”. FIG. 6 is a table showing a part of the map referred to by the CPU. FIG. 7 is a flowchart showing a routine executed by the CPU of the ECU of the control device according to the first embodiment. FIG. 8 is a flowchart showing a routine executed by the CPU of the ECU of the control device according to the first embodiment. FIG. 9 is a flowchart showing a routine executed by the CPU of the ECU of the control device according to the second embodiment.

  Hereinafter, control devices for internal combustion engines according to embodiments of the present invention will be described with reference to the drawings. In all the drawings of the embodiments, the same or corresponding parts are denoted by the same reference numerals. The embodiments described below are preferred specific examples of the present invention, and the contents of the present invention are not limited to these embodiments.

<First Embodiment>
(Constitution)
FIG. 1 shows a schematic configuration of an internal combustion engine to which a control device for an internal combustion engine according to a first embodiment of the present invention (hereinafter sometimes referred to as “first control device”) is applied.

  The engine 10 is an internal combustion engine mounted on a vehicle, and is a multi-cylinder (in this example, 4 cylinders), 4-cycle, spark ignition type gasoline engine. The engine 10 includes a spark plug 20, a main body 40, an intake system 50, an exhaust system 60, an EGR system 70, and a cooling device 100 shown in FIG.

  The main body 40 includes a cylinder block 41, a cylinder head 42, a piston 43, and an ignition coil 44. A combustion chamber 45 is formed in the main body 40 by a cylinder block 41, a cylinder head 42 and a piston 43.

  The spark plug 20 is mounted in a spark plug mounting hole 46 provided in the cylinder head 42. The spark plug 20 is connected to the ignition coil 44. The ignition coil 44 applies a high voltage to the spark plug 20 in response to an instruction from the ECU 80 described later.

  The intake system 50 includes an intake pipe 51, an intake port 52, an intake valve 53, a fuel injection valve 54, and a throttle valve 55. The intake valve 53 is disposed in the cylinder head 42 and is driven by an intake camshaft (not shown) to open and close the “communication portion between the intake port 52 and the combustion chamber 45”.

  The fuel injection valve 54 injects fuel into the intake port 52 in response to an instruction from the ECU 80. The throttle valve 55 is opened and closed by a throttle valve actuator 56 and adjusts the amount of air taken into the combustion chamber 45 in response to an instruction from the ECU 80.

  The exhaust system 60 includes an exhaust pipe 61, an exhaust port 62, and an exhaust valve 63. The exhaust valve 63 is disposed in the cylinder head 42 and is driven by an exhaust camshaft (not shown) to open and close the “communication portion between the exhaust port 62 and the combustion chamber 45”.

  The EGR system 70 includes an exhaust gas recirculation pipe 71 and an EGR control valve 72. The exhaust gas recirculation pipe 71 recirculates a part of the exhaust gas flowing through the exhaust pipe 61 to the intake pipe 51 as EGR gas. The EGR control valve 72 is disposed in the exhaust gas recirculation pipe 71. The EGR control valve 72 adjusts the amount of EGR gas flowing through the exhaust gas recirculation pipe 71 in response to an instruction from the ECU 80.

  The ECU (electronic control unit) 80 includes a CPU 81, a ROM 82 that stores a program executed by the CPU 81, a map (lookup table), and the like, and a RAM 83 as a storage unit that temporarily stores data. The ECU 80 acquires temperature information and the like from the temperature sensor S and various sensors 95 shown in FIG. 2, and performs engine control based on these. For example, the ECU 80 controls the actuator such as the ignition coil 44, the fuel injection valve 54, and the throttle valve actuator 56, and performs engine control for maintaining the engine 10 in a desired operation state. The CPU 81 includes a conversion coefficient acquisition unit that acquires a conversion coefficient, which will be described later, and a water temperature conversion unit that converts the combustion chamber ambient temperature detected by the temperature sensor S using the conversion coefficient into a control outlet ambient temperature. Function.

  As shown in FIG. 2, the engine 10 is provided with a water cooling type cooling device 100 for preventing overheating and overcooling.

  The cooling device 100 is provided in a passage (referred to as a “cooling water passage”) of cooling water (referred to as “cooling liquid, antifreeze liquid or in some cases LLC”) provided inside the main body 40, and to the outside 90 of the main body 40. A variety of devices 98 (devices such as a heater core and a radiator (not shown)) and a cooling water passage provided between the various devices 98 on the outside 90 are provided. The inside of the main body 40 has a water jacket 75a around the combustion chamber 45 provided in the cylinder block 41 and a head water jacket 75b above the combustion chamber 45 provided in the cylinder head 42 as cooling water passages.

  Cooling device 100 includes a water pump (not shown) for circulating cooling water. Specifically, the water pump is an electric water pump that can variably control the flow rate (flow velocity) of the cooling water.

  In the cooling device 100, the cooling water passes through the cooling water passage and circulates inside the main body 40 and the outside 90. As shown by the arrows, the cooling water circulates in the order of the cooling path R1, the cooling path R2, the cooling path R3, the cooling path R4, the cooling path R5, and the cooling path R1.

  The cooling path R1 is a cooling water passage from the entrance to the inside of the cooling water main body 40 to the water jacket 75a. The cooling path R <b> 2 is a water jacket 75 a provided in the cylinder block 41. The cooling path R <b> 3 is a cooling water passage including the head water jacket 75 b of the main body 40. The cooling path R <b> 4 is a cooling water passage between the various devices outside the main body 40 and the various devices. The cooling path R5 is a cooling water passage from the outside 90 to the inlet inside the main body 40. Note that one end of the cooling water passage constituting the cooling path R1 to the cooling path R3 constitutes an inlet portion through which the cooling water flows from the outside 90 of the main body 40 into the main body 40. The other end of the cooling water passage constituting the cooling paths R1 to R3 constitutes an outlet portion at a position Q where the cooling water flows out from the inside of the main body 40 to the outside 90 of the main body 40. The cooling water passage extends from the inlet portion to one of the combustion chambers 45, passes through the periphery of the plurality of combustion chambers 45, and then communicates with the outlet portion via the cylinder head 42.

  The cooling water circulating through the cooling path R1 to the cooling path R5 cools the main body 40 by removing the heat generated in the main body 40. The heated cooling water is sent to a radiator which is one of the devices 98 outside the main body 40, cooled by outside air, returned to the inside of the main body 40, and the main body 40 is cooled. As described above, the main body 40 can be kept at an appropriate temperature.

  The temperature sensor S is provided at a specific portion (specifically, around the combustion chamber 45) that can more accurately detect the temperature change of the combustion chamber 45 even when the flow rate of the cooling water is decreased. More specifically, the temperature sensor S is provided near the combustion chamber 45 in the water jacket 75a. More specifically, the temperature sensor S is a thermistor that detects the temperature of the cooling water around the combustion chamber, and supplies a signal corresponding to the detected temperature value to the ECU 80.

  Various sensors 95 are provided at predetermined positions of the engine 10 in order to detect the engine rotational speed NE, the engine load TQ, and the like. Various sensors 95 supply the ECU 80 with signals corresponding to the respective detection values. The engine load TQ is calculated by the CPU 81 of the ECU 80 based on the intake air amount detected by an air flow meter (not shown) that is one of the various sensors 95, the engine rotational speed NE, and the like. Here, the engine load TQ is an air filling rate (a value obtained by dividing the amount of air sucked into one combustion chamber in one intake stroke by the displacement of the cylinder), which is calculated. Since the method is well known in the art, a detailed description is omitted here.

(Overview of operation)
Next, the outline | summary of the action | operation which a 1st control apparatus performs is demonstrated. In the prior art, an outlet water temperature sensor is provided at a position Q (that is, around the outlet portion), and the temperature Tw detected by the outlet water temperature sensor is used when determining the control water temperature (fuel injection amount) of the engine 10. Water temperature).

  On the other hand, in the warm-up operation (the state until the warm-up of the engine 10 is finished), it is required to warm the main body 40 at an early stage. Therefore, the heat from the combustion chamber wall surface to the cooling water is reduced by reducing the flow rate of the cooling water. In some cases, it is difficult to transfer, or cooling water having a high kinematic viscosity characteristic (high viscosity LLC or variable viscosity LLC) having a low heat transfer coefficient at a low temperature as compared with conventional cooling water is used as cooling water.

  In these cases, since the amount of heat transferred from the combustion chamber wall surface to the cooling water in the warm-up operation decreases, the detected temperature of the outlet water temperature sensor is high when the flow rate of the cooling water is high and / or when normal LLC is used. Compared to a lower value. Therefore, if the amount of fuel injected and supplied to the engine 10 is controlled based on the temperature detected by the outlet water temperature sensor, the air-fuel ratio of the air-fuel mixture becomes excessively rich. That is, in these cases, the temperature of the combustion chamber wall surface estimated from the detected temperature of the outlet water temperature sensor is lower than the actual temperature of the combustion chamber wall surface, so the fuel injection correction amount (increase amount) becomes excessive, and actually the combustion Since the temperature of the chamber wall surface is high, more unburned fuel components evaporate among the unburned fuel components adhering to the combustion chamber wall surface. As a result, the air-fuel ratio of the air-fuel mixture becomes excessively rich, and fuel consumption and emissions are deteriorated.

  Therefore, the inventor of the present application has considered that the temperature sensor S is provided in the cooling water passage around the combustion chamber and the engine 10 is controlled based on the detected temperature Tn of the temperature sensor S.

  However, in the typical control of the engine 10, various controls including the fuel injection control are performed using the detected temperature at the position Q (the detected temperature of the outlet water temperature sensor) as the control water temperature. It is not preferable to use the detected temperature of the temperature sensor S that detects the temperature at another position as it is as the control water temperature.

  Therefore, as a result of further intensive studies, the inventor of the present application has acquired the relationship between the detected temperature Tn of the temperature sensor S and the detected temperature Tw of the outlet water temperature sensor in advance, so that the detected temperature of the temperature sensor S during the warm-up operation is obtained. It has been found that Tn can be converted to the detected temperature Tw of the outlet water temperature sensor using the relationship, and the temperature after the conversion can be used as the control water temperature Twn.

  More specifically, the inventor has an engine 10 (a temperature sensor S provided in the cooling water passage around the combustion chamber and an outlet water temperature sensor provided in the position Q (that is, around the outlet portion). The temperature Tn detected by the temperature sensor S during the warm-up operation and the temperature Tw detected by the outlet water temperature sensor are detected using the temperature detected by the temperature sensor S when the engine 10 is started. (Hereinafter, referred to as “starting temperature Tsta”.) Each time, and the rotation speed of the engine 10 (engine rotation speed) and the load of the engine 10 were maintained in various combinations. An example is shown in FIG. In FIG. 3, the line q1 is the detection temperature Tn of the temperature sensor S, the line q2 is the detection temperature Tw of the outlet water temperature sensor, and the line q3 is the control water temperature Twn.

  The reason for measuring the detected temperature Tn and the detected temperature Tw for each engine speed and engine load is that if the engine speed and the engine load are the same, it can be estimated that the amount of heat generated in the combustion chamber is constant. It is. In this case, the grid points (P (1) to P (k)) shown in FIG. 4 were used for the engine speed and the engine load. Although FIG. 4 shows the case of 8 points (k = 8), the number of lattice points may be at least 4 or more, and the upper limit is not limited.

  Furthermore, the starting temperature Tsta was set to q (qsta is an integer of 2 or more) (Tsta (1) to Tsta (q)) from the use temperature range assumed in advance by the engine 10. Actually, soaking is carried out until the lubricating oil temperature, the detected temperature Tw of the outlet water temperature sensor, and the detected temperature Tn of the temperature sensor S are equal to each starting temperature Tsta (that is, the state where the circulation of the cooling water is stopped). Then, the operation of the engine 10 was started and measurement was performed.

  Then, the inventor plotted the obtained experimental data on the graph shown in FIG. 5 for each starting temperature Tsta, engine speed NE, and engine load TQ. In FIG. 5, the horizontal axis is “Tn−Tsta (difference obtained by subtracting the starting temperature Tsta from the detected temperature Tn of the temperature sensor S)”, and the vertical axis is “(Tn−Tsta) / (Tw−Tsta)”. is there. Hereinafter, this graph is also referred to as a “map creation graph”.

  As can be understood from FIG. 5, the inventor has shown that “(Tn−Tsta) / (Tw−Tsta)” is a region where Tn−Tsta is equal to or less than T1. ) And a region where “(Tn−Tsta) / (Tw−Tsta)” is constant with respect to (Tn−Tsta) (that is, a region where Tn−Tsta is equal to or greater than T1). Got.

Therefore, first, a region in which “(Tn−Tsta) / (Tw−Tsta)” did not change with respect to (Tn−Tsta) and was a constant value (= αn, where n is an integer of 0 or more) was examined. . In this region, “Tw-Tsta” and “Tn-Tsta” have a linear relationship. Therefore, when the inventor has Tn−Tsta in this region, the following equation (1) is established. Therefore, the detected temperature Tw of the outlet water temperature sensor (ie, the following equation (2) modified from the equation (1)) It was concluded that the control water temperature Twn) can be estimated.

(Tn−Tsta) / (Tw−Tsta) = αn (1)

Tw = {(Tn−Tsta) / αn} + Tsta (2)

  From the above, the first control device stores the look-up table (map) that defines the relationship between the engine speed NE and the engine load TQ and the coefficient αn in the ROM 82 for each region of the starting temperature Tsta and (Tn−Tsta). Store it. Then, the first control device selects a lookup table from the starting temperature Tsta and the detected temperature Tn of the actual temperature sensor S, and adds the actual “starting temperature Tsta, engine speed NE, and The coefficient αn is obtained by applying the “engine load TQ”, and the control water temperature Twn (= Tw) is estimated by using the equation (2). The equation (2) is referred to as a first conversion equation, and the coefficient αn used in the first conversion equation is also referred to as a linear α-type conversion coefficient (first type coefficient) αn.

  Here, FIG. 6 shows an example of a part of the lookup table (two-dimensional map) of the conversion coefficient α1 (starting temperature Tsta = −30 ° C. and 0 ° C., T1 <Tn−Tsta <T2). According to this example, when the starting temperature Tsta = −30 ° C., the engine speed NE = 1000 [rpm], and the engine load TQ = 100 [Nm], c2 is specified as the conversion coefficient α1. Further, when the starting temperature Tsta = 0 ° C., the engine speed NE = 1500 [rpm], and the engine load TQ = 200 [Nm], d3 ′ is specified as the conversion coefficient α1.

  Next, a region where “(Tn−Tsta) / (Tw−Tsta)” is not a constant value with respect to (Tn−Tsta) was examined. In this region, “Tw-Tsta” and “Tn-Tsta” are in a non-linear relationship.

On the other hand, when the inventor has Tn−Tsta in this region, the increase amount ΔTn of the detection temperature Tn of the temperature sensor S in a predetermined time period is equal to the increase amount ΔTw of the detection temperature Tw of the outlet water temperature sensor in the predetermined time period. And found that there is a linear relationship. That is, the knowledge that the following formula (3) is established in this region was obtained.

{Tn (k) −Tn (k−1)} / {Tw (k) −Tw (k−1)} = βm (3)

Tn (k) is the detected temperature Tn of this time, Tn (k-1) is the detected temperature Tn of a predetermined time, Tw (k) is the detected temperature Tw of the current outlet water temperature sensor, and Tw (k-1) is This is the detected temperature Tw before a certain time. m is an integer greater than or equal to 0, and βm differs for each temperature region.

Therefore, based on the following equation (4) obtained by modifying the above equation (3), the control water temperature Twn that is equal to the detected temperature Tw of the outlet water temperature sensor can be sequentially estimated.

Tw (k) = {Tn (k) −Tn (k−1)} / βm + Tw (k−1) (4)

  From the above, the first control device stores the look-up table that defines the relationship between the engine rotational speed NE and the engine load TQ and the coefficient βm in the ROM 82 for each region of the starting temperature Tsta and (Tn−Tsta). deep. Then, the first control device selects a lookup table from the starting temperature Tsta and the detected temperature Tn of the actual temperature sensor S, and adds the actual “starting temperature Tsta, engine speed NE, and The coefficient βm is obtained by applying the “engine load TQ”, and the control water temperature Twn (= Tw) is sequentially estimated by using the equation (4). The above equation (4) is called a second conversion equation, and the coefficient βm used in the second conversion equation is also called a nonlinear β-type conversion coefficient (second type coefficient) βm.

(Specific operation)
Next, a specific operation performed by the first control device will be described.
The CPU 81 of the ECU 80 is configured to execute the routines shown in the flowcharts of FIGS. 7 and 8 every elapse of a predetermined time (specifically, 100 msec). First, when the CPU 81 starts processing from step 700 of the routine shown in the flowchart of FIG. 7, the CPU 81 proceeds to step 702 described below.

  In step 702, the CPU 81 acquires the temperature Tn detected by the temperature sensor S as the current temperature sensor value Tn (k). Next, in step 703, the CPU 81 reads the starting temperature Tsta from the RAM 83. Note that the CPU 81 intentionally operates when the engine 10 is started by changing an ignition key switch (not shown) from the off position to the on position, or as in a hybrid vehicle or an idling stop and start system. When the engine 10 is restarted, the temperature Tn detected by the temperature sensor S is acquired as the starting temperature Tsta and stored in the RAM 83.

  Next, the CPU 81 proceeds to step 705 and determines whether or not the temperature sensor value Tn (k) is smaller than the warm-up operation upper limit temperature value Tn_max. Thereby, the CPU 81 determines whether or not the engine 10 is in a warm-up operation.

  When the temperature sensor value Tn (k) is smaller than the warm-up operation upper limit temperature value Tn_max, the CPU 81 makes a “Yes” determination at step 705 to proceed to step 710 to turn on the warm-up operation determination flag. (Warm-up operation determination flag Flg_wa is set to “1”). Note that a process when the temperature sensor value Tn (k) is equal to or higher than the warm-up operation upper limit temperature value Tn_max (referred to as “process after step 755”) will be described later.

  Next, the CPU 81 determines whether or not the temperature sensor S is functioning normally. Specifically, the CPU 81 proceeds to step 715, and the temperature Tn detected by the temperature sensor S acquired at the time when this routine was executed last time (hereinafter referred to as “previous temperature sensor value Tn (k−1)”). Read from the RAM 83. Thereafter, the CPU 81 proceeds to step 725 to determine whether or not the temperature sensor S is normal based on the temperature sensor value Tn (k) and the previous temperature sensor value Tn (k−1).

  Whether the temperature sensor S is normal is determined as follows. That is, the temperature sensor value Tn (k) is a range in which the previous temperature sensor value Tn (k−1) has a predetermined value Buff (ie, Tn (k−1) −Baff ≦ Tn (k) ≦ Tn). If (k−1) + Baff), it is determined that the temperature sensor S is normal. On the other hand, when the temperature sensor value Tn (k) is within the range of the value obtained by adding the width of the predetermined value Buff to the previous temperature sensor value Tn (k−1), it is determined that the temperature sensor S is abnormal. To do.

  Specifically, in step 725, the CPU 81 determines whether or not the temperature sensor value Tn (k) is greater than “Tn (k−1) + Baff”. If the temperature sensor value Tn (k) is larger than “Tn (k−1) + Baff”, the CPU 81 determines “Yes” in step 725 and proceeds to step 730 to determine that the temperature sensor S is normal. The temperature sensor state determination flag is set to a value indicating normality (the temperature sensor state determination flag Flg_sn is set to “0”). Thereafter, the CPU 81 executes an appropriate process among the processes (temperature range determination and control water temperature calculation) in steps 800 to 850 shown in FIG.

  On the other hand, if the temperature sensor value Tn (k) is equal to or smaller than “Tn (k−1) + Baff”, the CPU 81 makes a “No” determination at step 725 to proceed to step 735, where the temperature sensor value Tn is “Tn ( It is determined whether or not the value is smaller than “k−1) −Baff”.

  When the temperature sensor value Tn (k) is smaller than “Tn (k−1) −Baff”, the CPU 81 determines “Yes” in step 735 and proceeds to step 730. In this case, the CPU 81 determines in step 730 that the temperature sensor S is normal, and sets the temperature sensor state determination flag to a value indicating that the temperature sensor S is normal (the temperature sensor state determination flag Flg_sn is “ Set to 0 ”). Thereafter, the CPU 81 executes an appropriate process among the processes (temperature range determination and control water temperature calculation) in steps 800 to 850 shown in FIG.

  On the other hand, if the temperature sensor value Tn (k) is equal to or greater than “Tn (k−1) −Baff”, the CPU 81 determines “No” in step 735 and proceeds to step 740. In this case, the CPU 81 determines in step 740 that the temperature sensor S is abnormal, and sets the temperature sensor state determination flag to a value indicating that the temperature sensor S is abnormal (the temperature sensor state determination flag Flg_sn is “ 1 ”).

  Next, the CPU 81 proceeds to step 745, and executes abnormal control (specifically, fuel cut, load restriction, etc.) set for the engine 10. Thereafter, the CPU 81 proceeds to step 750 and ends the processing of this routine.

(Processing after step 755)
If the temperature sensor value Tn (k) is greater than or equal to the warm-up operation upper limit temperature value Tn_max in step 705 described above (that is, the warm-up operation has been completed), the CPU 81 determines “No And proceeds to step 755 to turn off the warm-up operation determination flag (set the warm-up operation determination flag Flg_wa to “0”). Thereafter, the CPU 81 calculates the control water temperature Twn by sequentially performing the processes of steps 760 to 775 described below.

Step 760: The CPU 81 obtains the engine speed NE.
Step 765: The CPU 81 acquires the engine load TQ.
Step 770: The CPU 81 obtains the coefficient C after the warm-up operation by applying the engine speed NE and the engine load TQ to the map C = (Y_ (NE · TQ)) which is a lookup table.

  Step 775: The CPU 81 applies the acquired “temperature sensor value Tn (k), coefficient C and Tsta” to (conversion formula): Twn (k) = {(Tn (k) −Tsta) / C} + Tsta. Then, the control water temperature Twn is calculated. Thereafter, the CPU 81 proceeds to step 780, and the calculation process of the control water temperature Twn (k) in this routine ends. The ECU 80 controls the amount of fuel injected and supplied to the engine 10 based on the control water temperature Twn (k).

(Temperature range judgment and control water temperature calculation)
As described above, when the CPU 81 completes the process of step 730, the CPU 81 executes the process of the routine shown by the flowchart in FIG. 8, and the difference “Tn (k) obtained by subtracting the starting temperature Tsta from the temperature sensor value Tn (k). −Tsta ”is a plurality of temperature regions divided for each temperature (for example, T1 ° C., T2 ° C., T3 ° C. (T1 <T2 <T3)) in the map creation graph (see FIG. 5). It is determined whether the temperature range is included, and the control water temperature is obtained by performing processing according to each temperature range.

The temperature ranges in this example and the types of conversion coefficients used in each temperature range are as follows.
Temperature region 1: “Tn (k) −Tsta” <T1,
Conversion coefficient β1, calculation coefficient type: Non-linear β type (first type)
Temperature region 2: T1 ≦ “Tn (k) −Tsta” <T2,
Conversion coefficient α1, calculation coefficient type: linear α type (second type)
Temperature region T2 ≦ “Tn (k) −Tsta” <T3,
Conversion coefficient α2, calculation coefficient type: linear α type (second type)
Temperature region 3: T3 ≦ “Tn (k) −Tsta” <Tn_max−Tsta,
Conversion coefficient α3, calculation coefficient type: linear α type (second type)

  When the CPU 81 proceeds to step 800, it determines whether or not “Tn (k) −Tsta” is smaller than T1. When “Tn (k) −Tsta” is smaller than T1, the CPU 81 makes a “Yes” determination at step 800 and proceeds to step 804 to indicate the calculation coefficient type determination flag as a non-linear β type (first type). Set to a value (Flg_ab is set to “2”).

Thereafter, the CPU 81 sequentially performs the processing of steps 806 to 814 described below.
Step 806: The CPU 81 obtains the engine rotational speed NE.
Step 808: The CPU 81 acquires the engine load TQ.
Step 810: The CPU 81 selects a lookup table (map) of the conversion coefficient β1 corresponding to the starting temperature Tsta and the temperature region 1, and applies the engine speed NE and the engine load TQ to the map of the conversion coefficient β1. To obtain the value B1 (= {β1_Tsta (NE · TQ)} of the conversion coefficient β1. Note that {β1_Tsta (NE · TQ)} applies the engine speed NE and the engine load TQ to the map of the conversion coefficient β1. This means the value of the conversion coefficient β1 specified by doing so.
Step 812: The CPU 81 reads Twn (k−1) from the RAM 83.

  Step 814: The CPU 81 sets the temperature sensor value Tn (k), the previous temperature sensor value Tn (k-1), the previous control water temperature Twn (k-1), and the conversion coefficient B1 to the second equation (4). The control water temperature Twn (k) is calculated by applying the following formula: Twn (k) = {(Tn (k) −Tn (k−1)) / B1} + Twn (k−1).

Thereafter, the CPU 81 proceeds to step 815 to end the present routine tentatively. Then, the ECU 80 executes a fuel injection control routine (not shown) to determine the fuel injection amount F based on the control water temperature Twn (k), and supplies the fuel of the fuel injection amount F to the engine 10 by injection. To do. The fuel injection amount F is determined by the following equation (5), for example.

F = {1 + Fh (Twn (k))}. (Mc / 14.6) (5)

Mc is the amount of air that one cylinder takes in in one intake stroke.
14.6 is the stoichiometric air-fuel ratio.
Fh (Twn (k)) is a warm-up increase amount, and is a positive value that increases as Twn (k) decreases.

  On the other hand, if “Tn (k) −Tsta” is equal to or greater than T1 in step 800, the CPU 81 makes a “No” determination in step 800 and proceeds to step 816 to set the calculated coefficient type determination flag to a linear α. A value indicating the type (second type) is set (Flg_ab is set to “1”).

  Thereafter, the CPU 81 proceeds to step 818 to determine whether or not “Tn (k) −Tsta” is a value smaller than T2. When “Tn (k) −Tsta” is smaller than T2, the CPU 81 makes a “Yes” determination at step 818 and sequentially performs the processing of steps 820 to 826 described below.

Step 820: The CPU 81 obtains the engine rotational speed NE.
Step 822: The CPU 81 acquires the engine load TQ.
Step 824: The CPU 81 selects a lookup table (map) of the conversion coefficient α1 corresponding to the starting temperature Tsta and the temperature range 2, and applies the engine speed NE and the engine load TQ to the selected conversion coefficient α1 map. As a result, the value A1 (= {α1_Tsta (NE · TQ)}) of the conversion coefficient α1 is acquired. Note that {α1_Tsta (NE · TQ)} means the value of the conversion coefficient α1 specified by applying the engine rotational speed NE and the engine load TQ to the map of the conversion coefficient α1.

Step 826: The CPU 81 applies the temperature sensor values Tn (k) and A1 to the first conversion equation (T2 (k) = {(Tn (k) −Tsta) / A1} + Tsta) that is the equation (2). Then, the control water temperature Twn (k) is calculated.
Thereafter, the CPU 81 proceeds to step 828 to end the present routine tentatively. The ECU 80 controls the amount of fuel injected and supplied to the engine 10 based on the control water temperature Twn (k).

  On the other hand, if “Tn (k) −Tsta” is equal to or greater than T2, the CPU 81 makes a “No” determination at step 818 to proceed to step 830 to determine whether or not the temperature sensor value Tn is smaller than T3. Determine. When “Tn (k) −Tsta” is smaller than T3, the CPU 81 makes a “Yes” determination at step 830 to sequentially perform the processes of steps 832 to 838 described below.

Step 832: The CPU 81 obtains the engine rotational speed NE.
Step 834: The CPU 81 acquires the engine load TQ.
Step 836: The CPU 81 selects a lookup table (map) of the conversion coefficient α2 corresponding to the starting temperature Tsta and the temperature region 2, and applies the engine speed NE and the engine load TQ to the map of the conversion coefficient α2. Thus, the value A2 (= {α2_Tsta (NE · TQ)}) of the conversion coefficient α2 is acquired. Note that {α2_Tsta (NE · TQ)} means a value of the conversion coefficient α2 specified by applying the engine speed NE and the engine load TQ to the map of the conversion coefficient α2.

Step 838: The CPU 81 applies the temperature sensor values Tn (k) and A2 to the first conversion formula: Twn (k) = {(Tn (k) −Tsta) / A2} + Tsta, which is the above formula (2). Then, the control water temperature Twn (k) is calculated.
Thereafter, the CPU 81 proceeds to step 840 to end the present routine tentatively. The ECU 80 controls the amount of fuel injected and supplied to the engine 10 based on the control water temperature Twn (k).

  On the other hand, if the temperature sensor value Tn is equal to or greater than T3, the CPU 81 makes a “No” determination at step 830 to sequentially perform the processes of steps 842 to 848 described below.

Step 842: The CPU 81 acquires the engine rotational speed NE.
Step 844: The CPU 81 acquires the engine load TQ.
Step 846: The CPU 81 selects a lookup table (map) of the conversion coefficient α3 corresponding to the starting temperature Tsta and the temperature region 3, and applies the engine speed NE and the engine load TQ to the selected conversion coefficient α3 map. As a result, the value A3 (= {α3_Tsta (NE · TQ)}) of the conversion coefficient α3 is acquired. Note that {α3_Tsta (NE · TQ)} means the value of the conversion coefficient α3 specified by applying the engine speed NE and the engine load TQ to the map of the conversion coefficient α3.

Step 848: The CPU 81 applies the temperature sensor values Tn (k) and A3 to the first conversion formula: Twn (k) = {(Tn (k) −Tsta) / A3} + Tsta, which is the above formula (2). Then, the control water temperature Twn (k) is calculated.
Thereafter, the CPU 81 proceeds to step 850 to end the present routine tentatively. The ECU 80 controls the amount of fuel injected and supplied to the engine 10 based on the control water temperature Twn (k).

  According to the first control device, the temperature sensor S is provided in the cooling water passage around the combustion chamber, and detects the combustion chamber peripheral temperature Tn, which is the temperature of the cooling water passing through the same portion. Then, according to the relationship between the detected temperature Tn of the temperature sensor S and the detected temperature Tw of the outlet water temperature sensor acquired in advance, the detected temperature (combustion chamber ambient temperature Tn) of the temperature sensor S is the control water temperature used by the fuel control unit. Converted to Twn. As a result, it is possible to appropriately set the fuel injection amount in accordance with the temperature of the combustion chamber and its surroundings while using the conventional control method of the internal combustion engine, and thus the fuel consumption can be deteriorated. Can lower the sex.

Second Embodiment
A control device according to a second embodiment of the present invention (hereinafter, may be referred to as “second control device”) will be described. The second control device is different from the first control device only in the following points.
(1) In addition to the temperature sensor S, the second control device is further provided with an outlet water temperature sensor located at a point Q indicated by an arrow in FIG.
(2) Based on the temperature detected by the temperature sensor S and the outlet water temperature sensor, the control described later is performed.
Hereinafter, this difference (particularly, the difference (2)) will be mainly described.

(Specific operation)
A specific operation performed by the second control device will be described.
The CPU 81 of the ECU 80 executes the routine shown by the flowchart in FIG. 9 every elapse of a predetermined time. First, when starting the process from step 900, the CPU 81 proceeds to step 902 described below.

  In step 902, the CPU 81 acquires the temperature Tn detected by the temperature sensor S as the current temperature sensor value Tn (k). Next, in step 903, the CPU 81 reads the starting temperature Tsta from the RAM 83.

  Next, the CPU 81 proceeds to step 905 to determine whether or not the temperature sensor value Tn (k) is smaller than the warm-up operation upper limit temperature value Tn_max. As a result, the CPU 81 determines whether the engine 10 is in a warm-up operation.

  If the temperature sensor value Tn (k) is smaller than the warm-up operation upper limit temperature value Tn_max, the CPU 81 makes a “Yes” determination at step 905 and proceeds to step 910 to turn on the warm-up operation determination flag. (Warm-up operation determination flag Flg_wa is set to “1”). A process when the temperature sensor value Tn (k) is equal to or higher than the warm-up operation upper limit temperature value Tn_max will be described later.

  Next, the CPU 81 performs the processing of steps 715 to 750 similar to the control of the first control device, and determines whether or not the temperature sensor S is functioning normally. In this process, if the CPU 81 determines that the temperature sensor S is normal, it sets the temperature sensor state determination flag to a value indicating normality (sets the temperature sensor state determination flag Flg_sn to “1”). (Step 730).

  Next, the CPU 81 proceeds to step 915 to acquire a temperature difference DTnw (k) (= temperature sensor value Tn (k) −outlet water temperature sensor value Tw (k)). That is, the CPU 81 determines whether or not the flow rate of the cooling water is a low flow rate by controlling the flow rate or increasing the kinematic viscosity of the cooling water in order to determine from the temperature difference Dtnw (k), the temperature sensor value Tn (k). -Outlet water temperature sensor value Tw (k) = temperature difference DTnw (k) is calculated.

Next, the CPU 81 proceeds to step 920 to acquire the engine speed NE. Next, the CPU 81 proceeds to step 925 to acquire the engine load TQ. Next, the CPU 81 proceeds to step 930 to acquire the value of the reference temperature difference Dtnw0. The reference temperature difference Dtnw0 may select the map is a lookup table corresponding to the start-up temperature Tsta, on the map _{(Dtnw0 = {Dtnw 0 _Tsta (} NE · TQ)}), the engine rotational speed NE and the engine load By applying the TQ, the reference temperature difference value Dtnw0 is obtained. _{{Dtnw 0 _Tsta (NE · TQ} )} means the value of the reference temperature difference Dtnw ₀ specified by the map of the reference temperature difference Dtnw ₀ applying the engine speed NE and the engine load TQ. The reference temperature difference Dtnw ₀ can be obtained using an experimental engine. Similar to the first apparatus, by operating the experimental engine, experimental data is obtained for each starting temperature Tsta, engine rotational speed NE and engine load TQ, and the temperature difference in the warm-up operation complete state at this time is determined as the reference temperature. The difference is Dtnw ₀ . Then, a lookup table of the reference temperature difference Dtnw ₀ based on this is stored in the ROM 82.

  By determining whether or not the temperature difference DTnw (k) is smaller than the reference based on the reference temperature difference value Dtnw0, the flow rate of the cooling water becomes a low flow rate by flow rate control or higher kinematic viscosity of the cooling water. It is determined whether or not. More specifically, the CPU 81 proceeds to step 935 and determines whether or not the temperature difference DTnw (k) is larger than “reference temperature difference DTnw0 + Baff”. When the temperature difference DTnw (k) is larger than “reference temperature difference DTnw0 + Baff”, the CPU 81 makes a “Yes” determination at step 935 to proceed to step 940, and sets the temperature sensor determination flag to a value indicating that the temperature sensor S. (Temperature sensor determination flag Flg_sen is set to “2”).

  Thereafter, the CPU 81 calculates the control water temperature Twn (k) by executing the processes of steps 800 to 850 similar to those of the first control device. Thereafter, the CPU 81 proceeds to step 945, and the calculation process of the control water temperature Twn (k) in this routine is ended. The ECU 80 controls the amount of fuel injected and supplied to the engine 10 based on the control water temperature Twn (k).

  On the other hand, if the temperature difference DTnw (k) is smaller than the “reference temperature difference DTnw0 + Baff”, the CPU 81 makes a “No” determination at step 935 to proceed to step 955 to indicate that the temperature sensor determination flag is an outlet water temperature sensor. The temperature sensor determination flag Flg_sen is set to “1”. That is, when the temperature difference DTnw (k) is smaller than the reference temperature difference DTnw0, it is determined that the flow rate of the cooling water is close to the reference, and control is performed based on the outlet water temperature sensor value Tw (k). When the warm-up completion state and the cooling water flow rate are close to the reference, the difference between the temperature Tn (k) detected by the temperature sensor S and the temperature Tw (k) detected by the outlet water temperature sensor is small. There is no need to dare control. Therefore, such control is performed in the second control device.

  Thereafter, the CPU 81 proceeds to step 960 to end the processing of this routine once. Then, the ECU 80 controls the amount of fuel injected and supplied to the engine 10 based on the temperature Tw (k) detected by the outlet water temperature sensor.

  If the temperature sensor value Tn (k) is greater than the warm-up operation upper limit temperature value Tn_max in step 905 described above, the CPU 81 makes a “No” determination in step 905 to proceed to step 950, where The operation determination flag is turned off (the warm-up operation determination flag Flg_wa is set to “0”). Thereafter, the CPU 81 sets the temperature sensor determination flag Flg_sen to a value indicating that it is an outlet water temperature sensor in step 955 (the temperature sensor determination flag Flg_sen is set to “1”), and then the CPU 81 proceeds to step 960 to execute this routine. This process is temporarily terminated. Then, the ECU 80 controls the amount of fuel injected and supplied to the engine 10 based on the temperature Tw (k) detected by the outlet water temperature sensor.

  According to the 2nd control device, the same operation effect as the 1st control device can be acquired. Further, according to the second control device, when it is not necessary to control the fuel injection amount based on the control water temperature Twn converted from the detection temperature Tn of the temperature sensor S, the detection temperature Tw of the outlet water temperature sensor is set. Based on this, the amount of fuel injected and supplied to the engine 10 is controlled. Thus, more appropriate control can be performed when it is not necessary to control the fuel injection amount based on the control water temperature Twn converted from the detected temperature Tn of the temperature sensor S. As a result, the possibility that the fuel consumption is deteriorated can be further reduced.

<Modification>
Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible.

  In each embodiment, the temperature sensor S may be provided in the vicinity of the combustion chamber 45 in the head water jacket 75b, or provided in the vicinity of the combustion chamber 45 in the cylinder block 41 and the cylinder head 42. It may be done. In each embodiment, two or more temperature sensors S may be provided.

  In each embodiment, the cooling device 100 may include a mechanism that variably controls the cooling water flow rate (specifically, a thermostat that controls the flow rate of cooling water that flows to the radiator, an electronically controllable valve, or the like). .

  DESCRIPTION OF SYMBOLS 10 ... Engine, 20 ... Spark plug, 40 ... Main body, 41 ... Cylinder block, 42 ... Cylinder head, 43 ... Piston, 44 ... Ignition coil, 45 ... Combustion chamber, 46 ... Spark plug mounting hole, 50 ... Intake system, 51 DESCRIPTION OF SYMBOLS ... Intake pipe, 52 ... Intake port, 53 ... Intake valve, 54 ... Fuel injection valve, 55 ... Throttle valve, 56 ... Throttle valve actuator, 60 ... Exhaust system, 61 ... Exhaust pipe, 62 ... Exhaust port, 63 ... Exhaust valve 70 ... EGR system, 71 ... exhaust gas recirculation pipe, 72 ... EGR control valve, 75a ... water jacket, 75b ... head water jacket, 80 ... ECU, 81 ... CPU, 82 ... ROM, 83 ... RAM, 90 ... external, 95 ... Various sensors, 100 ... Cooling device

Claims (1)

One end portion constitutes an inlet portion to the main body of the cooling water internal combustion engine and the other end portion is a cooling water passage constituting an outlet portion from the main body of the internal combustion engine and passes around the combustion chamber of the internal combustion engine. A control device for an internal combustion engine comprising a cooling water passage through which a cooling water for cooling the periphery of the combustion chamber flows.
A temperature sensor that is provided at a specific portion around the combustion chamber and detects a temperature around the combustion chamber that is the temperature of the specific portion;
A fuel control unit that controls the amount of fuel injected and supplied to the internal combustion engine based on the water temperature around the outlet that is the temperature of cooling water that passes in the vicinity of the outlet;
With
After the start of the internal combustion engine for each combination of the start temperature which is the temperature around the combustion chamber at the start of the internal combustion engine, the engine speed after the start of the internal combustion engine and the engine load after the start of the internal combustion engine A storage unit storing a conversion coefficient defining a relationship between the combustion chamber ambient temperature and the outlet ambient water temperature in the form of a lookup table;
Applying the starting temperature detected by the temperature sensor when starting the internal combustion engine, the engine rotational speed after starting the internal combustion engine, and the engine load after starting the internal combustion engine to the look-up table, the conversion coefficient is calculated. A conversion coefficient acquisition unit to acquire;
A water temperature conversion unit that converts a combustion chamber ambient temperature detected by the temperature sensor after the start of the internal combustion engine into the outlet ambient temperature used by the fuel control unit using the acquired conversion coefficient;
The control apparatus of the internal combustion engine provided with.

Images