JPH08121293A - Idle rotational speed controller for internal combustion engine - Google Patents

Abstract

PURPOSE: To always maintain driving precision of an idle rotational speed control valve (ISC valve) properly by means of an inexpensive constitution requiring no dedicated temperature sensor or no special structure. CONSTITUTION: A target idle rotational speed is computed on the basis of an output from a cooling water temperature sensor 23 in an engine, and from an engine rotational speed detected by means of a rotational speed sensor 22 in the engine and the target idle rotational speed, a deviation in rotational speed is computed each time. On the other hand, a basic duty value for an ISC valve driving pulse is computed on the basis of the deviation in rotational speed and the like, and solenoid coil self-heat generating temperature of an ISC valve 18 is assumed on the basis of the basic duty value. The assumed coil self-heat generating temperature is added to the output of an intake temperature sensor 14, and coil temperature of the solenoid coil is computed, and then, on the basis of the computed coil temperature, the basic duty value is corrected sequentially.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for an internal combustion engine, and more particularly, to an adjustment accuracy of an idle speed control valve for adjusting the opening of a throttle valve bypass passage according to the amount of electricity supplied to a solenoid coil. The present invention relates to the improvement of the control device configuration for maintaining the above.

[0002]

2. Description of the Related Art As is well known in such an idle speed control device, a drive amount of an idle speed control valve (hereinafter referred to as an ISC valve) for adjusting an opening degree of an auxiliary air passage bypassing a throttle valve ( The opening degree) is determined according to the amount of electricity supplied to the solenoid coil.

Further, this energization amount is usually determined by the duty value of the pulse for driving the same ISC valve, and the basic duty value can also converge the engine speed under feedback control to the target speed during idling. It is calculated and set as a value.

However, in general, even if a pulse having a certain duty value is applied to the ISC valve, the coil resistance value of the solenoid coil changes depending on the temperature of the solenoid coil, and accordingly, the coil resistance value changes. The value of the current substantially flowing through the coil also changes. Therefore, even if the engine speed is feedback-controlled, the drive amount (opening degree) of the ISC valve may be manipulated to a value different from the original target value.

Therefore, in the prior art, for example, the actual exploitation Sho 62-124 is used.
As seen in the device described in Japanese Patent No. 257: 257, the temperature of the solenoid (coil) of the ISC valve is detected by a temperature sensor, and the energization amount is corrected based on the detected temperature. Alternatively, as seen in the device described in Japanese Patent Laid-Open No. 4-54252, the engine cooling water whose temperature is detected by the cooling water temperature sensor is introduced in the vicinity of the solenoid (coil) to predict the coil temperature, and the predicted temperature. The energization amount is corrected based on The adoption of the idle speed control method is being considered.

[0006]

As described above, if the coil temperature can be detected or predicted, the IS amount is corrected by correcting the energization amount based on the detected or predicted temperature.
It is certainly possible to operate the drive amount of the C valve to a target value.

However, all of the above conventional devices require a dedicated temperature sensor for detecting the temperature of the solenoid (coil) or use a cooling water temperature sensor used for normal engine control. However, it is necessary to route the engine cooling water to the vicinity of the same solenoid (coil) and the system configuration is complicated and expensive.

Other conventional idle speed control devices include, for example, a device for detecting the ambient temperature of an engine (such as an outside air temperature sensor, as shown in the device described in Japanese Patent Application Laid-Open No. 2-227556). One of the ISC valve drive characteristic curves is selected based on the output of the intake air temperature sensor), and the ISC valve drive amount at each time is determined based on the selected characteristic curve and the output of the cooling water temperature sensor. A device that employs such a control method has also been proposed.

According to such a control method, the idle rotation speed control device can be constructed as a relatively inexpensive system, but the ISC valve drive amount (opening degree) caused by the above-mentioned temperature change of the solenoid coil itself. The deviation cannot be corrected.

The present invention has been made in view of the above circumstances, and it is possible to always maintain appropriate drive accuracy of an ISC valve while having an inexpensive structure that does not require a dedicated temperature sensor or a special structure. An object of the present invention is to provide an idle speed control device for an internal combustion engine.

[0011]

In order to achieve such an object, the invention according to claim 1 is arranged in an auxiliary air passage for bypassing a throttle valve of an internal combustion engine, and the auxiliary is provided in accordance with the amount of electricity supplied to a solenoid coil. An ISC valve for adjusting the opening degree of the air passage, a target idle speed calculation means for calculating a target speed when the engine is in an idle state,
Basic energization amount calculation means for calculating a basic energization amount to the solenoid coil so that the engine speed becomes the calculated target idle speed, and the temperature of the solenoid coil is estimated based on the ambient temperature of the ISC valve. Coil temperature estimating means, energizing amount correcting means for sequentially correcting the calculated basic energizing amount according to the estimated temperature of the solenoid coil, and driving means for driving the ISC valve with the corrected energizing amount. And an idle speed control device for an internal combustion engine.

Further, in the invention of claim 2, in the structure of the invention of claim 1, when an intake air temperature sensor for measuring the temperature of the intake air is already installed in the engine, the coil temperature is The estimating means is configured to estimate the temperature of the solenoid coil based on the intake air temperature measured by the intake air temperature sensor.

According to the third aspect of the invention, the auxiliary air passage that bypasses the throttle valve of the internal combustion engine is arranged,
An ISC valve that adjusts the opening of the auxiliary air passage according to the amount of electricity to the solenoid coil, a target idle speed calculation unit that calculates a target speed when the engine is in an idle state, and an engine speed A basic energization amount calculating means for calculating a basic energization amount to the solenoid coil for achieving the calculated target idle speed, and a solenoid coil of the solenoid coil based on the ambient temperature of the ISC valve and the self-heating temperature of the solenoid coil. Coil temperature estimating means for estimating the temperature, energizing amount correcting means for successively correcting the calculated basic energizing amount according to the estimated temperature of the solenoid coil, and the ISC valve with the corrected energizing amount. And an idle speed control device for an internal combustion engine, which comprises a driving means for driving.

According to a fourth aspect of the present invention, in the configuration of the third aspect of the invention, when the engine is provided with an intake air temperature sensor for measuring the temperature of the intake air, the coil temperature is The estimating means is configured to estimate the temperature of the solenoid coil based on the intake air temperature measured by the intake air temperature sensor and the self-heating temperature of the solenoid coil.

According to a fifth aspect of the present invention, in the configuration of the third or fourth aspect of the invention, the coil temperature estimating means controls the self-heating temperature of the solenoid coil according to the calculated basic energization amount. To be estimated.

Further, in the invention according to claim 6, in the configuration of the invention according to claim 3 or 4, the coil temperature estimating means controls the self-heating temperature of the solenoid coil according to the corrected energization amount. Configure as an estimator.

Further, in the invention according to claim 7, in the configuration of the invention according to claim 5 or 6, the coil temperature estimating means is configured to cause the solenoid coil to self-operate in accordance with a value obtained by reducing the change in the energization amount. It is configured to estimate the heat generation temperature.

Further, in the invention according to claim 8, in the configuration of the invention according to claim 5 or 6, the coil temperature estimating means is configured to determine the self-heating temperature of the solenoid coil estimated according to the energization amount. It is configured to estimate the self-heating temperature of the solenoid coil as a value with a slowed change.

According to a ninth aspect of the invention, in the configuration of the invention according to any one of the fourth to eighth aspects, the coil temperature estimating means includes the measured intake air temperature and the estimated solenoid. The temperature of the solenoid coil is calculated as the sum of the self-heating temperature of the coil.

[0020]

In the structure of the invention according to claim 1, the IS
The C valve, the target idle rotation speed calculation means, and the basic energization amount calculation means constitute a conventional well-known idle rotation speed control device.

On the other hand, the coil temperature estimating means uses, as the ambient temperature of the ISC valve, a temperature sensor such as an intake air temperature sensor or an outside air temperature sensor (these temperature sensors are usually already installed as engine control sensors). The coil temperature of the ISC valve is estimated by referring to the output. For example, in the case of an ISC valve having a resin housing, it has been confirmed that the coil temperature and the intake air temperature are very close to each other. If the correlation with the ambient temperature is known, the coil temperature can be estimated based on the ambient temperature.

As described above, the value of the current flowing through the solenoid coil changes depending on the coil temperature, but the manner and amount of change in the current value depending on the coil temperature have been empirically determined beforehand. You can ask.

In the energization amount correction means, a correction coefficient corresponding to the estimated coil temperature is introduced on the basis of the manner and amount of change in the current value depending on the coil temperature thus obtained, and the basic energization is performed. Correct the amount.

Therefore, if the ISC valve is driven by the driving means on the basis of the corrected energization amount, it is an inexpensive structure which does not require a dedicated temperature sensor or a special structure. The drive amount of the ISC valve can always be maintained properly.

Further, according to the invention of claim 2,
When the intake air temperature sensor for measuring the temperature of the intake air is already installed in the engine, the coil temperature estimating means is provided: -The temperature of the solenoid coil based on the intake air temperature measured by the intake air temperature sensor. What to estimate. With this configuration, it is possible to easily and accurately estimate the coil temperature, especially when the ISC valve is configured to have a resin housing. As described above, in the case of the ISC valve having the resin housing, it has been confirmed that the coil temperature and the intake temperature are very close to each other.

Also in the configuration of the invention according to claim 3, the ISC valve, the target idle speed calculation means,
The basic energization amount calculation means constitutes a conventional well-known idle rotation speed control device.

On the other hand, in this case, the coil temperature estimating means is
The coil temperature of the ISC valve is estimated based on the ambient temperature of the ISC valve and the self-heating temperature of the solenoid coil.

The solenoid coil also has a resistance value, and as long as a current flows through it, a predetermined amount of self-heating due to Joule heat occurs. The temperature of the self-heating can also be empirically obtained in advance as a value corresponding to the amount of energization at each time.

Therefore, as with the coil temperature estimating means,
If the coil temperature is estimated based on the two information of the ambient temperature of the ISC valve and the self-heating temperature of the solenoid coil, more accurate temperature information can be obtained as the same coil temperature.

Further, the energization amount correction means introduces a correction coefficient according to the estimated coil temperature based on the changing manner and the changing amount of the current value depending on the coil temperature to introduce the basic energizing amount. It is as above-mentioned that it corrects.

Therefore, also in this case, the structure is inexpensive and does not require a dedicated temperature sensor or a special structure.
The drive amount of the ISC valve can always be maintained properly. Moreover, in this case, since the coil temperature is estimated with higher accuracy, the driving accuracy of the ISC valve can be maintained at a higher level.

According to the invention of claim 4,
When an intake air temperature sensor for measuring the temperature of the intake air is already installed in the engine, the coil temperature estimating means is used to: Intake air temperature measured by the intake air temperature sensor and self-heating temperature of the solenoid coil. That estimates the temperature of the solenoid coil based on In this case as well, particularly when the ISC valve is configured to have a resin housing, the accuracy is higher than that of the coil temperature estimating means according to the present invention. Thus, the coil temperature can be estimated.

According to the invention of claim 5,
The coil temperature estimation means estimates the self-heating temperature of the solenoid coil according to the calculated basic energization amount. With this configuration, the self-heating temperature of the solenoid coil can be estimated efficiently and highly accurately based on the basic energization amount calculated each time.

According to the invention of claim 6,
The coil temperature estimating means estimates the self-heating temperature of the solenoid coil according to the corrected energization amount. With this configuration, for example, the self-heating temperature of the solenoid coil can be estimated with higher accuracy based on the amount of current supplied actually last time.

Further, the coil temperature estimation means estimates the self-heating temperature of the solenoid coil according to the invention as set forth in claim 7: Alternatively, according to the invention of claim 8, the self-heating temperature of the solenoid coil is estimated as a blunted value of the change in the self-heating temperature of the solenoid coil estimated according to the energization amount. If configured as described above, for example, even in the control initial stage where the value of the calculated basic energization amount is likely to change suddenly, without impairing the followability of the idle rotation speed feedback control,
The engine speed can be stably converged to the target value. That is, since the coil temperature due to this self-heating gradually follows the change even if the amount of electricity supplied to the coil changes, the coil temperature to be estimated is calculated as a value that is blunted in this way. It becomes possible to preferably suppress a rapid change in the energization amount to the solenoid coil in the initial stage of control.

As a method of such blunting, a so-called smoothing process in which a sample value for each time is corrected to a value closer to the estimated value used last time and the estimated value is used this time,
Alternatively, there is a so-called averaging process in which an average value of a predetermined number of sample values in the past is used as an estimated value each time.

According to the invention of claim 9,
The coil temperature estimating means calculates the temperature of the solenoid coil as a sum of the measured intake air temperature and the estimated self-heating temperature of the solenoid coil. With this configuration, the coil temperature can be estimated as a more realistic temperature.

[0038]

1 shows an embodiment of an idle speed control device for an internal combustion engine according to the present invention.

The apparatus of this embodiment does not require any special temperature sensor or special structure for measuring the solenoid coil temperature of the ISC valve, and the drive accuracy of the ISC valve does not depend on the solenoid coil temperature. It is configured as a device that can be properly maintained.

First, the overall construction of the apparatus of this embodiment will be described with reference to FIG. A multi-cylinder internal combustion engine (hereinafter referred to as an engine) 1 includes a piston 3 in a cylinder 2, and a combustion chamber 4 defined by a cylinder head 1a and a cylinder block 1b is formed above the piston 3. There is. A spark plug 16 is provided in the combustion chamber 4.

Further, the combustion chamber 4 has an intake passage 7 and an exhaust passage 8 via an intake valve 5 and an exhaust valve 6, respectively.
Is in communication with. On the other hand, a fuel injection valve 9 for each cylinder is provided in the intake passage 7, and a surge tank 10 for suppressing air pulsation during intake is provided in the intake passage 7 upstream of the fuel injection valve 9. Has been. This surge tank 10
A throttle valve 11 which is opened / closed in conjunction with the operation of an accelerator pedal (not shown) is provided on the further upstream side, and the amount of intake air to the intake passage 7 is adjusted by opening / closing the throttle valve 11. A throttle opening sensor 12 that detects the opening of the throttle valve 11 is provided near the throttle valve 11.

A thermal air flow meter 13 is provided on the upstream side of the throttle valve 11.
The actual amount of intake air introduced into the intake passage 7 is detected by 3.

Further, an intake air temperature sensor 14 for detecting intake air temperature is provided between the thermal air flow meter 13 and the throttle valve 11, and an air cleaner 15 is provided upstream of the thermal air flow meter 13. Are provided respectively. The intake air temperature detected by the intake air temperature sensor 14 is used to convert the volumetric flow rate detected by the flow meter 13 into a mass flow rate when calculating the fuel injection amount.

With this structure of the intake system, the intake air is sent to the downstream side of the intake passage 7 via the air cleaner 15, the thermal air flow meter 13, the throttle valve 11 and the surge tank 10, and the intake passage In the vicinity of the intake valve 5, downstream of 7, the fuel is injected into the fuel injection valve 9 to form a mixture. The air-fuel mixture is introduced into the combustion chamber 4 via the intake valve 5.

In the engine 1, the air-fuel mixture introduced into the combustion chamber 4 is exploded by the spark of the spark plug 16 to obtain a driving force. Then, the exhaust gas after the combustion is discharged to the exhaust passage 8 via the exhaust valve 6.

On the other hand, the intake passage 7 is provided with a bypass passage 17 as an auxiliary air passage that bypasses the throttle valve 11 and connects the upstream side of the throttle valve 11 and the surge tank 10.

In the middle of the bypass passage 17,
The above-mentioned IS as an actuator for adjusting the auxiliary air amount
A C valve 18 is provided. This ISC valve 18
Consists of a 1-coil rotary solenoid valve,
The valve body 18a rotates by exciting a solenoid coil (not shown). The amount of rotation of the valve body 18a is determined according to the amount of excitation of the solenoid coil,
The larger the valve body 18a is rotated, the larger the opening of the bypass passage 17 is. When the solenoid coil is demagnetized, the valve body 18a rotates in the direction to close the bypass passage 17 to fully close the bypass passage 17. The drive amount of the ISC valve 18 (opening degree of the bypass passage 17) is adjusted to an arbitrary value through duty ratio control by pulse width modulation.

In addition, the distributor 20 is for distributing the high voltage output from the igniter 21 to each of the spark plugs 16 in synchronization with the crank angle of the engine 1. Each ignition timing of the spark plug 16 is determined by the output timing of the high voltage from the igniter 21. The distributor 20 is provided with a rotation speed sensor 22 that detects a crank angle from the rotation of the rotor of the distributor 20 and outputs a pulse signal.

The sensor 23 attached to the water jacket of the engine 1 is a cooling water temperature sensor for detecting the cooling water temperature of the engine 1, and the sensor 24 provided near the intake system detects the ambient temperature. It is an outside air temperature sensor.

The detection signals from the above sensors are taken into the electronic control unit 30. The electronic control unit 30 is composed of, for example, a microcomputer, and is a unit that comprehensively controls the drive of the above-mentioned ISC valve 18, including the fuel injection valve 9 and the igniter 21, based on the detection signals from the respective sensors. is there.

FIG. 2 shows a functional structure of the electronic control unit 30 mainly as an idle speed control device. Hereinafter, with reference to FIG. 2 together, the idle speed control of the embodiment will be described. The function and operation of the device will be described in more detail.

In the electronic control unit 30 shown in FIG.
The target rotation speed calculation unit 31 is a unit that calculates the target rotation speed during idling, that is, the target idle rotation speed TNE, based on the cooling water temperature THW measured by the cooling water temperature sensor 23.

To calculate the target idle speed TNE, a cooling water temperature map (table) as shown in FIG. 3, for example, is used. That is, the target rotation speed calculation unit 31
Then, at the predetermined sampling cycle, the cooling water temperature THW
Is read, and a target idle speed TNE determined corresponding to the cooling water temperature THW at each time is calculated through the map illustrated in FIG. The calculated target idle speed TNE is given to the subtractor 32.

The subtractor 32 uses the target idle speed T
This is a portion for subtracting the actual rotational speed NE of the engine 1 measured through the rotational speed sensor 22 from NE to obtain a rotational speed deviation ΔNE with respect to the target rotational speed TNE. The obtained rotational speed deviation ΔNE is taken into the basic duty value calculation unit 34 as the feedback amount (F / B) of the idle rotational speed control.

Further, the idle determining section 33 inputs the throttle opening TA measured through the throttle opening sensor 12, and when the throttle opening TA is below a predetermined opening, the operating condition of the engine 1 is This is the part that is determined to be equivalent to an idle. The determination result is also given to the basic duty value calculator 34.

The basic duty value calculation unit 34 provides the basic duty value Duty for the drive pulse of the ISC valve 18 under the condition that the idle determination unit 33 determines that the engine 1 is in the idle operation state.
This is a part for calculating B.

Here, this basic duty value DutyB
Is an element Duty (F / B) determined by the feedback amount (F / B) output from the subtractor 32.
And the factor Duty determined by the cooling water temperature THW
(THW) and an added value of an element Duty (electrical load) determined by the state of the electric load (for example, whether or not the air conditioner or the power steering device is operating), that is, DutyB = Duty (F / B) + Duty ( THW) + Duty (electrical load) (1)

Incidentally, the above feedback amount (F / B)
For the element Duty (F / B) determined by, a value corresponding to the rotational speed deviation ΔNE at each time is calculated through a map (table) as shown in FIG. 4, for example.

As the element Duty (THW) determined by the cooling water temperature THW, a value corresponding to the cooling water temperature THW is calculated through a map (table) as shown in FIG. 5, for example.

The element Duty (electrical load) determined by the state of the electric load has a value corresponding to the electric load (current i) at each time through a map (table) as shown in FIG. 6, for example. Is calculated. In particular,
For example, the basic duty value DutyB is corrected in such a manner that it increases by 10% when the air conditioner is operating and increases by 5% when the power steering device is operating.

The basic duty value DutyB calculated in this way by the basic duty value calculation unit 34 is given to the coil temperature calculation unit 35 and the final duty value calculation unit 37, respectively.

The coil temperature calculation unit 35 determines the ISC valve 1 based on the given basic duty value DutyB.
The solenoid coil self-heating temperature To of No. 8 is estimated and calculated, and the intake coil temperature TM measured by the intake temperature sensor 14 is added to the obtained coil self-heating temperature To to calculate the solenoid coil temperature Tc. is there.

Here, the solenoid coil self-heating temperature To of the ISC valve 18 is estimated and calculated according to the basic duty value DutyB given each time through a map (table) as shown in FIG. 7, for example. . The characteristics of the map illustrated in FIG. 7 are derived from experimental values of the coil temperature increase mode for various duty values of the drive pulse applied to the solenoid coil.

In the apparatus of the same embodiment, the above I
Assuming that the SC valve 18 is a one-coil rotary solenoid type valve having a resin housing, its coil temperature is very close to the intake air temperature TM as compared with, for example, one having a housing made of aluminum die casting. Has been confirmed. That is, in the ISC valve 18 having such a resin housing, the amount of heat received from the engine 1 main body is extremely small, and most of the coil temperature is
It is governed by the temperature of the air passing through the valve 18, that is, the intake air temperature TM.

Therefore, as in the coil temperature calculation unit 35, the intake air temperature TM is further corrected by the estimated coil self-heating temperature To, that is, Tc = TM + To (2) By calculating, it becomes possible to obtain accurate temperature information about the coil temperature Tc without using any dedicated temperature sensor or the like. The coil temperature Tc thus obtained is further provided to the correction coefficient calculation unit 36.

The correction coefficient calculating section 36 is a section for calculating the correction coefficient Cc for the basic duty value DutyB according to the given coil temperature Tc. The value of the current flowing through the solenoid coil changes according to the coil temperature Tc. The method of changing the current value depending on the coil temperature Tc and the amount of change are known. For example, the correction coefficient Cc of the basic duty value DutyB that compensates for the current value change caused by the temperature change with the coil temperature Tc = 20 ° C. as a reference is as shown in FIG.

Therefore, in the correction coefficient calculation unit 36, as shown in FIG.
The duty value correction coefficient Cc corresponding to the coil temperature Tc given each time is calculated based on the map (table) shown in FIG. The calculated duty value correction coefficient Cc is given to the final duty value calculation unit 37.

The final duty value calculation unit 37 performs a correction on the basic duty value DutyB given from the basic duty value calculation unit 34 based on the duty value correction coefficient Cc to calculate the final duty value Duty. Is.

That is, the final duty value calculation unit 37
Then, with respect to the basic duty value DutyB, an operation such as Duty = DutyB × Cc (3) by the duty value correction coefficient Cc is executed to calculate the final duty value Duty. The calculated final duty value Duty is finally given to the solenoid drive unit 38.

The solenoid drive section 38 performs well-known pulse width modulation based on the given final duty value Duty to generate a drive pulse for the ISC valve 18, and drives the ISC valve 18 by the generated pulse. As described above with reference to FIG. 1, the opening degree of the bypass passage 17 is controlled according to the drive amount of the ISC valve 18, that is, the rotation amount of the valve body 18a. Also, the duty value Duty of this drive pulse
Is a value corrected according to the coil temperature of the ISC valve 18, and the drive amount (opening degree of the bypass passage 17) is also
It is always controlled to an appropriate value regardless of the coil temperature.

As described above, according to the apparatus of this embodiment, the driving accuracy of the ISC valve 18 can always be properly maintained even though it has an inexpensive structure that does not require any dedicated temperature sensor or special structure. Will be able to.

By the way, in the apparatus of the present embodiment, the coil temperature calculation unit 35 causes the basic duty value D given each time.
It is assumed that the self-heating temperature To of the solenoid coil of the ISC valve 18 is estimated and calculated directly from utyB based on the map illustrated in FIG. 7.

However, as described above, the basic duty value Du
When the coil self-heating temperature To is calculated directly from tyB, the calculated coil self-heating temperature To also tends to change suddenly in the early stage of control when the given basic duty value DutyB is likely to change suddenly. Further, when the calculated value of the coil self-heating temperature To changes suddenly in this way,
The driving amount itself of the ISC valve 18 is likely to change suddenly. However, the actual coil temperature To due to this self-heating
Even if the amount of electricity supplied to the coil changes, it is not immediately reflected, and gradually follows the change in the amount of electricity supplied.

Therefore, for the coil temperature calculation processing by the coil temperature calculation unit 35, so-called smoothing processing as exemplified in FIG. 9 is adopted to stabilize the engine speed NE at its target value TNE. It is effective in making it converge.

The details will be described below. That is,
In the coil temperature calculation process (annealing process 1) shown in FIG. 9, the coil temperature calculation unit 35 inputs the current value DutyB (i) of the basic duty value in step 101,
In the next step 102, a smoothing operation calculation based on a ratio such as, for example, DutyB ′ (i) = 0.1 × DutyB (i) + 0.9 × DutyB ′ (i−1) (4) is executed. Here, DutyB ′ (i) is the currently calculated smoothing duty value, and DutyB ′ (i−1) is the previously used smoothing operation of the same calculation process that is repeatedly executed at a predetermined cycle such as a one-second cycle. It is a duty value.

Thus, the smoothed duty value DutyB '
In step 103, the coil calculation unit 35 that obtains (i) estimates and calculates the coil self-heating temperature To corresponding to the obtained smoothed duty value DutyB ′ (i) based on the map of FIG. .

After that, as in the case of the above embodiment, the intake air temperature TM is read in step 104, the addition operation of the equation (2) is executed in step 105 to obtain the coil temperature Tc, and then step At 106, the obtained coil temperature Tc is output to the correction coefficient calculation unit 36.

By repeatedly executing such coil temperature calculation processing (annealing processing 1) through the coil calculation unit 35, the sudden change of the estimated coil self-heating temperature To can be suitably suppressed, and the coil temperature Tc and Sudden changes in the correction coefficient Cc and the final duty value Duty are also suppressed, and stable driving of the ISC valve 18 is ensured.

FIG. 11 shows the transition of the obtained smoothed duty value DutyB ′ (i) for reference. Incidentally, in FIG. 11, the solid line shows the transition of the basic duty value DutyB (i) given each time, and the broken line shows the transition of the basic duty value DutyB (i) through the calculation of the equation (4). The transition of the smoothed duty value DutyB '(i) is shown.

Further, in the coil temperature calculation processing (annealing processing 1), the basic duty value DutyB (i),
That is, although the input value when the map self-heating temperature To is calculated is smoothed, as shown in FIG. 10, the map output value, that is, the coil self-heating temperature To You may make it smoothen. Even with such a processing method, it is possible to obtain substantially the same effect as the coil temperature calculation processing (annealing processing 1).

The details will be described below. That is,
In the coil temperature calculation process (annealing process 2) shown in FIG. 10, the coil temperature calculation unit 35 inputs the current value DutyB (i) of the basic duty value in step 201,
In step 202, the coil self-heating temperature To (i) corresponding to the basic duty value DutyB (i) is estimated and calculated based on the map of FIG.

Then, in the coil temperature calculation unit 35, in the next step 203, for example, To ′ (i) = 0.1 × To (i) based on the estimated current self heating temperature To (i) of the coil. The smoothing operation based on the ratio of + 0.9 × To ′ (i−1) (5) is executed. Here, To '(i) is the coil self-heating temperature annealing value to be obtained this time, and To' (i-1) is also the previous value of the same calculation process repeatedly executed at a predetermined cycle such as a one second cycle. It is the coil self-heating temperature annealing value used.

Thus, the coil self-heating temperature annealing value To '
The coil calculation unit 35 that has obtained (i) then performs step 2
The intake air temperature TM is read at 04, and at step 205,
The coil temperature Tc is obtained by executing an addition operation such as Tc = TM + To ′ (i) (2) ′ by the coil self-heating temperature smoothing value To ′ (i), and in step 206, the obtained coil is calculated. The temperature Tc is output to the correction coefficient calculator 36.

Even if the coil temperature calculation process (nameling process 2) is repeatedly executed through the coil calculating unit 35, a rapid change in the coil self-heating temperature To is preferable as in the coil temperature calculation process (nameling process 1). Therefore, the coil temperature Tc, the correction coefficient Cc, and the sudden change of the final duty value Duty are also suitably suppressed. And I
Stable driving of the SC valve 18 is ensured.

FIG. 12 shows the transition of the coil self-heating temperature annealing value To ′ (i) obtained above for reference. Incidentally, in FIG. 12, the solid line shows the transition of the coil self-heating temperature To (i) calculated by map each time, and the broken line shows the transition of the coil self-heating temperature To (i) by the equation (5). 7 shows the transition of the coil self-heating temperature annealing value To ′ (i) obtained through the calculation of

Further, the basic duty value DutyB is not limited to the coil temperature calculation processing (the smoothing processing 1) and the coil temperature calculation processing (the smoothing processing 2), and the averaging shown in FIG. (I) Alternatively, the change in the coil self-heating temperature To (i) can be slowed down.

Incidentally, FIG. 13 shows the basic duty value D
An example is shown in which the averaging process is applied to utyB (i) to slow down the change. Thus, the average values DutyB (a1), DutyB (a2) of a predetermined number of past sample values,
In order to realize stable idle rotation speed feedback control, the same effect as the above-described smoothing process can be obtained by calculating the map of the estimated value for each time based on DutyB (a3), DutyB (a4) ,. be able to.

Further, in the apparatus of the previous embodiment, as is clear from FIG. 2, the coil temperature calculation unit 35 makes the coil self-heating temperature To based on the basic duty value DutyB calculated by the basic duty value calculation unit 34. Is calculated by map.

However, instead of such a configuration, for example, FIG.
4, the final duty value Duty calculated by the final duty value calculator 37 is given to the coil temperature calculator 35, and the coil self-heating temperature To is map-calculated based on the final duty value Duty. You can also

According to such a configuration, the self-heating temperature To of the coil is actually calculated on the basis of the duty value of the pulse applied to the solenoid coil of the ISC valve 18, so that the coil temperature is calculated. Also in the section 35, the coil temperature Tc can be estimated with higher accuracy. The estimated map of the coil self-heating temperature To illustrated in FIG.
Needless to say, the same applies to uty.

Further, in the apparatus of the above embodiment, the basic value of the coil temperature Tc is obtained based on the intake air temperature TM measured by the intake air temperature sensor 14, but instead of the intake air temperature sensor 14, for example, the outside air temperature. The sensor 24 (FIG. 1) may be used to obtain the basic value of the coil temperature Tc based on the outside air temperature measured by the outside air temperature sensor 24.

When the outside air temperature sensor 24 or another ambient temperature measuring sensor is used, the coil temperature T
If the correlation between c and their ambient temperature is clear, the coil temperature Tc can be accurately estimated based on those temperatures.

Further, in estimating the coil temperature Tc, the correction by the coil self-heating temperature To can be omitted. In this case, although the accuracy is a little inferior, the processing such as the map calculation of the coil self-heating temperature To and the above-described smoothing processing and averaging processing are unnecessary, and the control can be performed more simply and at low cost. The device can be embodied.

In the apparatus of the above embodiment, it is assumed that the ISC valve 18 is a one-coil rotary solenoid type valve having a resin housing. However, as the ISC valve, other types of valves such as a linear solenoid valve can be similarly used. Further, according to the control device of the present invention, it is possible to obtain appropriate driving accuracy for valves of other types as well, regardless of the coil temperature.

Further, in the apparatus of the above embodiment, the engine idle determination is made based on the value of the throttle opening TA, but in the case where a so-called idle switch is provided, the on / off of the switch is turned on / off. The configuration may be such that the idle determination is performed based on the off state.

[0096]

As described above, according to the present invention, the driving accuracy of the ISC valve does not depend on the coil temperature of the ISC valve, although the structure is inexpensive and does not require any dedicated temperature sensor or special structure. You will be able to maintain it properly.

Therefore, the engine speed can be stably and reliably converged to the target value (target idle speed).

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an idle speed control device of the present invention.

FIG. 2 is a block diagram showing a functional configuration of the electronic control device shown in FIG.

FIG. 3 is a graph showing a calculation mode of a target idle speed based on an engine cooling water temperature.

FIG. 4 is a graph showing a calculation mode of a basic duty value element based on a feedback amount.

FIG. 5 is a graph showing a calculation mode of a basic duty value element based on cooling water temperature.

FIG. 6 is a graph showing a calculation mode of a basic duty value element by an electric load.

FIG. 7 is a graph showing a calculation mode of a coil self-heating temperature based on a basic duty value.

FIG. 8 is a graph showing a manner of calculating a duty value correction coefficient based on coil temperature.

FIG. 9 is a flowchart showing a main process procedure of the coil temperature calculation unit shown in FIG.

FIG. 10 is a flowchart showing another smoothing processing procedure of the coil temperature calculation unit.

FIG. 11 is a time chart showing an example of execution by the smoothing processing of FIG. 9.

FIG. 12 is a time chart showing an example of execution by the smoothing processing of FIG.

FIG. 13 is a time chart showing an example of execution by averaging processing.

FIG. 14 is a block diagram showing another configuration example of the electronic control device shown in FIG. 1.

[Explanation of symbols]

1 ... Engine, 2 ... Cylinder, 3 ... Piston, 4 ... Combustion chamber, 5 ... Intake valve, 6 ... Exhaust valve, 7 ... Intake passage,
8 ... Exhaust passage, 9 ... Fuel injection valve, 10 ... Surge tank,
11 ... Throttle valve, 12 ... Throttle opening sensor, 13 ... Thermal air flow meter, 14 ... Intake air temperature sensor, 15
... Air cleaner, 16 ... Spark plug, 17 ... Bypass passage, 18 ... ISC valve, 20 ... Distributor,
21 ... Igniter, 22 ... Rotation speed sensor, 23 ... Cooling water temperature sensor, 24 ... Outside air temperature sensor, 30 ... Electronic control device,
31 ... Target rotation speed calculation unit, 32 ... Subtractor, 33 ... Idle determination unit, 34 ... Basic duty value calculation unit, 35 ... Coil temperature calculation unit, 36 ... Correction coefficient calculation unit, 37 ... Final duty value calculation unit, 38 … Solenoid drive.

Claims (9)

[Claims] 1. An idle speed control valve, which is arranged in an auxiliary air passage that bypasses a throttle valve of an internal combustion engine and adjusts the opening of the auxiliary air passage in accordance with the amount of electricity to a solenoid coil, and the engine is idle. Target idle speed calculation means for calculating a target speed when the engine is in a state, and basic energization amount calculation for calculating a basic energization amount to the solenoid coil so that the engine speed becomes the calculated target idle speed. Means, coil temperature estimating means for estimating the temperature of the solenoid coil based on the ambient temperature of the idle speed control valve, and the calculated basic energization amount is sequentially corrected according to the estimated temperature of the solenoid coil. An internal combustion engine comprising: an energization amount correction means; and a drive means for driving the idle rotation speed control valve with the corrected energization amount. Idle speed control device for Seki. 2. An intake air temperature sensor for measuring the temperature of intake air of the engine is installed in the engine, and the coil temperature estimating means comprises:
The idle speed control device for an internal combustion engine according to claim 1, wherein the temperature of the solenoid coil is estimated based on an intake air temperature measured by the intake air temperature sensor. 3. An idle speed control valve, which is arranged in an auxiliary air passage that bypasses a throttle valve of an internal combustion engine and adjusts the opening degree of the auxiliary air passage in accordance with the amount of electricity supplied to a solenoid coil, and the engine is idle. Target idle speed calculation means for calculating a target speed when the engine is in a state, and basic energization amount calculation for calculating a basic energization amount to the solenoid coil so that the engine speed becomes the calculated target idle speed. Means, coil temperature estimating means for estimating the temperature of the solenoid coil based on the ambient temperature of the idle speed control valve and the self-heating temperature of the solenoid coil, and the coil temperature estimating means for calculating the temperature of the solenoid coil according to the estimated temperature of the solenoid coil. And an energizing amount correcting means for sequentially correcting the basic energizing amount, and a driving unit for driving the idle speed control valve with the corrected energizing amount. Idle speed control apparatus for an internal combustion engine, characterized in that it comprises a means. 4. An intake air temperature sensor for measuring the temperature of intake air of the engine is installed in the engine, and the coil temperature estimating means comprises:
The idle speed control device for an internal combustion engine according to claim 3, wherein the temperature of the solenoid coil is estimated based on an intake air temperature measured by the intake air temperature sensor and a self-heating temperature of the solenoid coil. 5. The idle speed control device for an internal combustion engine according to claim 3, wherein the coil temperature estimating means estimates the self-heating temperature of the solenoid coil according to the calculated basic energization amount. 6. The idle speed control device for an internal combustion engine according to claim 3, wherein the coil temperature estimating means estimates the self-heating temperature of the solenoid coil according to the corrected energization amount. 7. The idle speed control device for an internal combustion engine according to claim 5, wherein the coil temperature estimating means estimates the self-heating temperature of the solenoid coil according to a value obtained by blunting a change in the energization amount. 8. The coil temperature estimating means estimates the self-heating temperature of the solenoid coil as a blunted change in the self-heating temperature of the solenoid coil estimated according to the energization amount. An idle speed control device for an internal combustion engine as described above. 9. The coil temperature estimating means calculates the temperature of the solenoid coil as a sum of the measured intake air temperature and the estimated self-heating temperature of the solenoid coil. 15. An idle speed control device for an internal combustion engine according to claim 15.