JP2007063994A - Valve temperature estimating device of internal combustion engine and valve clearance quantity estimating device using this device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a valve temperature estimating device capable of accurately estimating the valve temperature in response to an operation condition. <P>SOLUTION: This valve temperature estimating device of an internal combustion engine is characterized by calculating a basic value TVISTD of the valve temperature on the basis of the engine cooling water temperature TWN as the temperature of a valve installing part in a cylinder, and calculating a correction value TVIHOS on the basis of any one or more of the suction air volume, an engine speed, a valve conversion angle or the target equivalent ratio, and calculating the valve temperature TVI by correcting its basic value TVISTD by the correction value TVIHOS. Since the valve temperature is calculated in response to the suction air volume, the engine speed, the valve conversion angle and the target equivalent ratio of reflecting the operation condition, the valve temperature can be highly accurately estimated in conformity with the operation condition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine, and more particularly to a technique for estimating a valve temperature for air-fuel ratio control of an air-fuel mixture and a technique for estimating a valve clearance amount using the same.

In order to control the air-fuel ratio of the air-fuel mixture as accurately as possible in an internal combustion engine, a technique for estimating the valve temperature on the intake side as described in Patent Documents 1 to 3 has been proposed. The technique described in Patent Document 1 calculates the valve temperature based on the elapsed time after starting. In the technique described in Patent Document 2, the valve temperature is calculated from the engine coolant temperature and the number of ignitions. And the technique of patent document 3 is calculating the valve temperature from engine cooling water temperature, catalyst temperature, and oil temperature (physical temperature different from cooling water).
JP-A-8-49581 (paragraphs 0027 to 0028) JP-A-8-61115 (paragraphs 0027 to 0028) JP-A-9-177578 (paragraphs 0024 to 0027)

  The above-described conventional valve temperature estimation apparatus has an improvement in that the error cannot be ignored because the temperature cannot be estimated according to the operating conditions. That is, in the case of the technique described in Patent Document 1, the valve temperature is obtained simply by adding the correction value for the elapsed time after the start to the engine coolant temperature, and a fine temperature estimation according to the operating conditions after the start is performed. Cannot be performed, and a large error may occur. In this case, it is necessary to store a correction value for each elapsed time for each coolant temperature at the time of starting, and the memory capacity and calculation load are large. Further, in the case of the technique described in Patent Document 2, the valve temperature is calculated from the engine coolant temperature and the number of ignitions, but it cannot cope with the operating conditions in which the intake air amount and the target equivalent ratio change even with the same number of ignitions. Large errors can occur. Furthermore, in the case of the technique described in Patent Document 3, the initial value of the valve temperature at the time of starting is only predicted from the temperature difference between the engine coolant temperature, the catalyst temperature, and the oil temperature. Temperature estimation cannot be performed, and a large error may occur.

  In view of such improvements, the present invention proposes a valve temperature estimation device that can accurately estimate the valve temperature according to operating conditions, and further proposes a valve clearance amount estimation device that uses the valve temperature.

  An internal combustion engine valve temperature estimation device according to the present invention calculates a basic value of a valve temperature based on the temperature of a valve installation site in a cylinder, and is any one of an intake air amount, an engine rotational speed, a valve conversion angle, or a target equivalent ratio. The valve temperature is calculated by calculating a correction value based on at least one and correcting the basic value with the correction value.

  According to the valve temperature estimation device of the present invention, the valve temperature is calculated according to the intake air amount, the engine rotation speed, the valve conversion angle, and the target equivalence ratio reflecting the operating conditions. A high valve temperature can be estimated.

FIG. 1 schematically shows an embodiment of a multi-cylinder gasoline engine provided with a valve temperature estimating device according to the present invention.
The cylinder head of the engine is provided with an intake valve 1 and an exhaust valve 2 each having a variable valve mechanism around a spark plug for each cylinder. The lift characteristics (open / close timing) of the intake valve 1 and the exhaust valve 2 are such that the phase of the cams 5 and 6 with respect to the crankshaft (valve conversion angle) is determined by the variable valve solenoids 3 and 4 provided on the intake side and exhaust side, respectively By adjusting the valve timing, the valve timing can be controlled. The cam angles of the cams 5 and 6 are measured by cam sensors 7 and 8.

  An electronic control throttle valve 11 for controlling the amount of intake air is provided in the intake passage 10 from the air cleaner to the intake port through the surge tank and manifold, and an air flow meter 12 and a downstream side of the electronic control throttle valve 11 are provided. In addition, an intake pressure sensor 13 for each cylinder is installed. An injector 14 faces the intake port immediately before the intake valve 1 to form an air-fuel mixture. The injector 14 may be a direct injection type that directly injects into the combustion chamber. On the other hand, an exhaust pressure sensor 21, an exhaust temperature sensor 22, and an oxygen sensor 23 for each cylinder are provided in the exhaust passage 20 from the exhaust port through the manifold and the catalyst to the muffler.

The operations of the variable valve solenoids 3 and 4, the electronically controlled throttle valve 11, and the injector 14 in the engine are controlled by an ECU (engine control unit) 30, and in synchronization with this, the ECU 30 performs an internal power coil built-in ignition coil 31 (ignition plug). In other words, the ignition timing is also controlled.
For these controls, the ECU 30 receives signals from various sensors. That is, the cam sensors 7 and 8 for detecting the cam angle, the air flow meter 12 for detecting the intake air amount, the intake pressure sensor 13 for detecting the intake pressure, the exhaust pressure sensor 21 for detecting the exhaust pressure, and the exhaust temperature for detecting the exhaust gas temperature. Sensor 22, oxygen sensor 23 for detecting the oxygen concentration in the exhaust, water temperature sensor 32 for detecting the temperature of engine cooling water, crank angle sensor 33 for detecting the crank angle and obtaining the engine rotation speed, cylinder head wall temperature In response to the outputs of the wall temperature sensor 34 for detecting the acceleration and the accelerator opening sensor 35 for detecting the accelerator opening, the arithmetic processing is executed.

The ECU 30 estimates the temperature of the intake / exhaust valves 1 and 2 and performs more accurate control when controlling the air-fuel ratio of the air-fuel mixture by the variable valve solenoids 3 and 4, the electronically controlled throttle valve 11, the injector 14, and the like. Execute. A valve temperature estimation device for this purpose will be described starting with respect to the intake valve 1.
In this example, the ECU 30, which is a calculation means for calculating the valve temperature, calculates the basic value TVISTD based on the engine coolant temperature TWN as the temperature of the valve installation site (cylinder head in this embodiment) for the intake valve temperature TVI. In the case of this embodiment, the correction value TVIHOS is calculated based on the current engine speed Ne, and is estimated as follows. The configuration of the arithmetic processing executed by the ECU 30 is shown in a block diagram in FIG.

  First, in the valve temperature basic value calculation block B1, the ECU 30 calculates a basic value TVISTD of the intake valve temperature based on the engine coolant temperature TWN. In this example, the corresponding basic value TVISTD is read from the basic value map MTVISTD stored in advance in a memory such as a ROM. The basic value map MTVISTD is obtained by mapping the basic value TVISTD in relation to the engine coolant temperature TWN, whereby the basic value TVISTD corresponding to the current operating condition is calculated. It is possible to input the wall temperature of the cylinder head by the wall temperature sensor 34 as the temperature of the valve installation site, but measuring the temperature of the engine coolant flowing through the cylinder head is closer to the valve. This is preferable because the temperature can be captured.

  On the other hand, in the valve temperature correction value calculation block B2, the ECU 30 calculates the valve temperature correction value TVHOS based on the current engine speed Ne. In this example, the corresponding correction value TVIHOS is read from the correction value map MTVIHOS stored in advance in a memory such as a ROM. The correction value map MTVIHOS is obtained by mapping the correction value TVIHOS in relation to the engine rotational speed Ne. With this correction value TVIHOS, it is possible to calculate a valve temperature with high accuracy corresponding to the operating conditions.

  The ECU 30 uses the basic value TVISTD from the basic value calculation block B1 and the correction value TVIHOS from the correction value calculation block B2, and multiplies the basic value TVISTD by the correction value TVIHOS in the valve temperature calculation block B3, thereby obtaining the intake valve temperature. Calculate TVI. The calculated intake valve temperature TVI can be used, for example, for estimation of an actual valve clearance amount by a later-described valve clearance amount estimation device, and greatly contributes to the calculation of the actual valve clearance amount with high accuracy.

By executing such arithmetic processing, it is possible to calculate a fine valve temperature in accordance with changes in operating conditions, and the accuracy is greatly improved. In addition, the memory capacity and calculation load for storing the correction value for each elapsed time for each coolant temperature at the time of starting are unnecessary, and the estimation accuracy is increased by simple calculation without increasing the memory capacity and calculation load. .
A flowchart of the calculation process is shown in FIG.

  First, in step S1 in FIG. 3, the ECU 30 reads the engine coolant temperature TWN, and in step S2, calculates a corresponding basic value TVISTD from the basic value map MTVISTD (basic value calculation block B1 in FIG. 2). Subsequently (or in parallel), in step S3, the ECU 30 reads the engine rotational speed Ne. In step S4, the correction value TVIHOS is calculated from the correction value map MTVIHOS (correction value calculation block B2 in FIG. 2), and in step S5, the intake valve temperature TVI is calculated from TVISTD × TVIHOS (valve temperature calculation block in FIG. 2). B3).

Next, a valve temperature estimation device for the exhaust valve 2 will be described.
In this example, the ECU 30, which is a calculation means for calculating the valve temperature, calculates the basic value TVESTD based on the exhaust gas temperature TEXH as the temperature of the valve installation site for the exhaust valve temperature TVE. By calculating the correction value TVEHOS based on the engine speed Ne, it is estimated as follows. The configuration of arithmetic processing executed by the ECU 30 is shown in a block diagram in FIG.

  First, in the valve temperature basic value calculation block B10, the ECU 30 calculates a basic value TVESTD of the exhaust valve temperature based on the exhaust gas temperature TEXH. Similar to the intake valve, the corresponding basic value TVESTD is read from the basic value map MVTESTD previously stored in a memory such as a ROM. The basic value map MVTESTD is obtained by mapping the basic value TVESTD in relation to the exhaust gas temperature TEXH, and thereby the basic value TVESTD corresponding to the current operating condition is calculated. In this case, it is possible to input the engine coolant temperature TWN as the temperature of the valve installation site, but in the case of the exhaust side, the exhaust gas temperature TEXH discharged through the exhaust valve 2 can be measured. This is used in this example because it is possible.

  In a valve temperature correction value calculation block B11, a valve temperature correction value TVHOS is calculated based on the current engine speed Ne. Similarly to the intake valve, the corresponding correction value TVEHOS is read from the correction value map MVEHOS stored in advance in a memory such as a ROM. The correction value map MTVEHOS is obtained by mapping the correction value TVEHOS in relation to the engine rotational speed Ne. With this correction value TVEHOS, it is possible to calculate a valve temperature with high accuracy according to the operating conditions.

  The ECU 30 uses the basic value TVESTD by the basic value calculation block B10 and the correction value TVEHOS by the correction value calculation block B11. In the valve temperature calculation block B12, the ECU 30 multiplies the basic value TVESTD by the correction value TVEHOS, thereby TVE is calculated. The calculated exhaust valve temperature TVE can be used, for example, for estimation of an actual valve clearance amount by a later-described valve clearance amount estimation device, and greatly contributes to the calculation of the actual valve clearance amount with high accuracy.

By executing such arithmetic processing, the same operation and effect as those of the intake valve 1 can be obtained in estimating the temperature of the exhaust valve 2.
FIG. 5 shows a flowchart of the calculation process related to the exhaust valve temperature.
First, in step S10 in FIG. 5, the ECU 30 reads the exhaust gas temperature TEXH, and in step S11, calculates the corresponding basic value TVESTD from the basic value map MVTESTD (basic value calculation block B10 in FIG. 4). Subsequently (or in parallel), in step S12, the ECU 30 reads the engine speed Ne. In step S13, the correction value TVEHOS is calculated from the correction value map MTVEHOS (correction value calculation block B11 in FIG. 4). In step S14, the exhaust valve temperature TVE is calculated by TVESTD × TVEHOS (valve temperature calculation block in FIG. 4). B12).

  In each of the above embodiments, the engine speed Ne is used for estimating the temperature of the intake / exhaust valve. However, any one of the intake air amount, the valve conversion angle, and the target equivalence ratio, which expresses other operating conditions, is also used. Alternatively, the correction values TVIHOS and TVEHOS may be mapped in advance and used for these combinations. For example, the correction value maps MTVIHOS and MTVEHOS when the valve conversion angle Va is used are as shown in FIG. 6 (intake valve) and FIG. 7 (exhaust valve). In this way as well, it is possible to calculate a highly accurate valve temperature that closely corresponds to the operating conditions.

In controlling the variable valve solenoids 3 and 4 and the associated ignition timing by the ECU 30, it is also important to calculate the actual valve clearance amount according to the operating conditions. A valve clearance amount estimation device for this purpose will be described.
In this example, the ECU 30, which is a calculation means for calculating the actual valve clearance amount, inputs the engine coolant temperature TWN by the water temperature sensor 32 as the temperature of the valve installation part in the cylinder in order to calculate the reference amount VCLRSTD of the valve clearance. . Further, the ECU 30 calculates the valve clearance correction amount VCLRVAR using the valve temperature TV (TVI, TVE) by the valve temperature estimation device. Then, the ECU 30 calculates the actual valve clearance amount under the current operating conditions by correcting the calculated reference amount of the valve clearance with the correction amount. A flowchart of the calculation process is shown in FIG. 8, and the configuration of the calculation process is shown in a block diagram in FIG.

  When the process for estimating the actual valve clearance amount is started with a predetermined period or valve timing control, the ECU 30 reads the engine coolant temperature TWN by the water temperature sensor 32 in step S20. In step S21, a reference amount VCLRSTD of the valve clearance is calculated from the read engine coolant temperature TWN. This reference amount calculation is executed in the reference amount calculation block B20 in FIG.

  In the reference amount calculation block B20, a reference amount map MSTD in which the valve clearance reference amount VCLRSTD is associated with the engine coolant temperature TWN is stored in the ROM of the ECU 30, and the reference amount map MSTD is determined according to the actually measured engine coolant temperature TWN. The corresponding reference amount VCLRSTD is read out by accessing. The reference amount map MSTD is created in advance by associating the amount of change in valve clearance due to thermal deformation of the valve clearance-related components with the engine coolant temperature TWN and storing it in the memory. The valve clearance-related parts are, for example, a cylinder head, a valve, a valve seat, a valve guide, a valve lifter, a retainer, and a cam base circle. The total change amount of the valve clearance due to thermal deformation of these valve clearance-related parts is a reference amount VCLRSTD. It is stored in the reference amount map MSTD.

  In this way, by creating and accessing a map in advance, the amount of thermal deformation of the cylinder head and the valve can be calculated, or the amount of thermal deformation can be calculated separately for the umbrella radial direction and the axial direction of the valve. This eliminates the need to perform calculation, simplifies the calculation process, and reduces the calculation load and memory capacity. In addition, by calculating the reference amount from the engine coolant temperature, simple processing is sufficient.

When the calculation of the reference amount VCLRSTD of the valve clearance is completed (or in parallel), the valve temperature TV is read in step S22, and the correction amount VCLRVAR of the valve clearance is calculated in the subsequent step S23. This correction amount calculation is executed in the correction amount calculation block B21 in FIG.
In the correction amount calculation block B21, the valve temperature TV, the engine coolant temperature TWN, the previously known valve thermal expansion coefficient THEREXP, the valve stem length VSTEM, and the ratio of the umbrella diameter to the stem length VRATIO are used. Thus, the correction amount VCLRVAR is calculated by Formula 1: VCLRVAR = VSTEM × VRATIO × THEREXP × (TV−TWN).

  As the valve temperature TV, when calculating the intake valve 1, the intake valve temperature TVI by the valve temperature estimating device is used, and when calculating the exhaust valve 2, the exhaust valve temperature TVE by the valve temperature estimating device is used. In estimating the valve temperature, an example in which the engine cooling water temperature TWN is used for calculating the basic values TVISTD and TVESTD for both the intake and exhaust valves 1 and 2 is possible. Since both are calculated based on the same engine coolant temperature TWN, it is useful for reducing the memory capacity and the calculation load. Alternatively, an example in which the engine cooling water temperature TWN is used for calculating the basic value TVISTD of the intake valve 1 and the exhaust gas temperature TEXH is used for calculating the basic value TVESTD of the exhaust valve 2 is also possible. This is useful when the exhaust temperature sensor 22 is provided in the exhaust port.

  In Formula 1, the reference amount VCLRSTD obtained from the engine coolant temperature TWN is calculated by calculating the difference between the engine coolant temperature and the actual valve temperature by TV-TWN and multiplying this by the thermal expansion coefficient THEREPP. A correction value that increases accuracy is calculated so as to be more in line with the actual value. Then, by multiplying the stem length VSTEM (initial value), which is each shape and physical property value of the intake / exhaust valves 1 and 2, and the ratio VRATIO of the umbrella diameter to the stem length, a coefficient is obtained, and this is the THEREX × (TV-TWN ) To calculate the correction amount VCLRVAR. By performing the calculation of VSTEM × VRATIO, it is possible to easily process with a simplified model calculation without solving the heat receiving and radiating of the valve. Therefore, it is not necessary to calculate the amount of thermal deformation separately for the umbrella diameter direction and the axial direction of the valve, the calculation process is simplified, and the calculation load and the memory capacity can be reduced.

  When the correction amount VCLRVAR is calculated, the process proceeds to step S24 to calculate the actual valve clearance amount VCL. In the actual valve clearance amount calculation block B22 of FIG. 9 that executes this calculation, the correction amount VCLRVAR is added to the reference amount VCLRSTD to correct, and finally the actual valve clearance amount VCL is calculated.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows embodiment of the engine provided with the valve temperature estimation apparatus which concerns on this invention. The block diagram explaining the structure of the valve temperature calculation of an intake valve. The flowchart which showed an example of the intake valve temperature calculation process. The block diagram explaining the structure of the valve temperature calculation of an exhaust valve. 6 is a flowchart showing an example of an exhaust valve temperature calculation process. The figure which showed the other example of the correction value map regarding an intake valve. The figure which showed the other example of the correction value map regarding an exhaust valve. The flowchart which showed an example of the actual valve clearance amount calculation process. The block diagram explaining the structure of actual valve clearance amount calculation.

Explanation of symbols

1, 2 Valve 3, 4 Variable valve solenoid 5, 6 Cam 7, 8 Cam sensor 12 Air flow meter 30 ECU
32 Water temperature sensor 33 Crank angle sensor B1, B10 Valve temperature basic value calculation block B2, B11 Valve temperature correction value calculation block B3, B12 Valve temperature calculation block

Claims (6)

  Calculating a basic value of the valve temperature based on the temperature of the valve installation site in the cylinder and calculating a correction value based on any one or more of the intake air amount, the engine rotation speed, the valve conversion angle, or the target equivalent ratio, A valve temperature estimation device for an internal combustion engine, wherein a valve temperature is calculated by correcting a basic value with the correction value.   2. The valve temperature estimating device for an internal combustion engine according to claim 1, wherein the engine coolant temperature is used as the temperature of the valve installation site.   2. The valve temperature estimating apparatus for an internal combustion engine according to claim 1, wherein an exhaust gas temperature is used as the temperature of the valve installation site.   A valve clearance amount estimation device for an internal combustion engine, wherein an actual valve clearance amount is calculated based on the valve temperature calculated by the valve temperature estimation device according to any one of claims 1 to 3.   3. A valve clearance amount estimation for an internal combustion engine, wherein the actual valve clearance amounts of the intake valve and the exhaust valve are calculated based on the intake valve temperature and the exhaust valve temperature calculated by the valve temperature estimation device according to claim 2. apparatus. An actual valve clearance amount of the intake valve is calculated based on the intake valve temperature calculated by the valve temperature estimation device according to claim 2, and the exhaust valve temperature is calculated based on the exhaust valve temperature calculated by the valve temperature estimation device according to claim 3. An apparatus for estimating a valve clearance amount of an internal combustion engine, wherein an actual valve clearance amount is calculated.

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