JPH07150971A - Control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To accurately carry out various sorts of adaptive control although the cooling water temperature of an internal combustion engine is detected by means of a water temperature sensor having rough accuracy. CONSTITUTION:A thermostat 50 and a water temperature sensor 4 are arranged in a thermostat case 41 integrated with the cooling water outlet side of an internal combustion engine 40, and cooling water temperature is detected with the water temperature sensor 4. When the cooling water temperature of the engine 40 rises and reaches the decided temperature, the thermostat 50 makes the water passage from the close state to the open state so as to freely pass cooling water. Then when the cooling water temperature begins to lower and reaches the decided temperature, the thermostat 50 makes the water passage from the open state to the close state, so as to control the cooling water temperature in the engine 40 in a decided temperature range. By utilizing the accurate characteristic of the thermostat 50 against the cooling water temperature, deviation of the detected temperature of the water temperature sensor 4 and the actual cooling water temperature is corrected, and hence the cheap sensor can be adopted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine control device for executing various adaptive controls by detecting the temperature of cooling water.

[0002]

2. Description of the Related Art Conventionally, as a prior art document related to an internal combustion engine controller, one disclosed in Japanese Patent Publication No. 3-50101 is known.

This system has two water temperature sensors for detecting the temperatures of a low temperature part and a high temperature part of an internal combustion engine, and a correction value obtained by correcting one detected temperature with the other detected temperature and a preset set value. It is said that it is possible to accurately control various combustion control devices of the internal combustion engine by comparing the above with the above to obtain an accurate internal combustion engine temperature.

[0004]

By the way, the water temperature sensor used conventionally has a thermistor characteristic in which the resistance value decreases as the cooling water temperature rises as shown in FIG. The cooling water temperature is detected based on the change. In order to ensure accuracy at high temperature in various combustion controls of the internal combustion engine, this water temperature sensor is, for example, in the cooling water temperature range Ta to Tb even for the resistance value R1 in the high temperature region
Since it is necessary to employ a sensor having relatively high-precision characteristics in which the variation between the sensors is suppressed to be small, the cost is high.

Therefore, the present invention has been made in order to reduce the production cost, and an object thereof is to provide an internal combustion engine control device capable of ensuring the accuracy at high temperature even if a low-priced water temperature sensor is used.

[0006]

An internal combustion engine control device according to the present invention is an internal combustion engine control device for performing various adaptive controls based on a cooling water temperature of an internal combustion engine, the cooling water temperature detecting the cooling water temperature. After the detection means and the cooling water temperature reach a preset specific temperature, the cooling water temperature control means for controlling the transition to a predetermined temperature range in which the specific temperature is set as an upper limit temperature. And a cooling water temperature correction means for correcting the cooling water temperature detected by the cooling water temperature detection means based on the upper limit temperature or the lower limit temperature of the predetermined temperature range in the cooling water temperature control means. .

[0007]

In the present invention, the cooling water temperature detected by the cooling water temperature detecting means is utilized by utilizing the characteristic that the cooling water temperature is controlled so as to reach the preset specific temperature and transit within the predetermined temperature range. Is corrected based on the upper limit temperature or the lower limit temperature of the predetermined temperature range. That is, even when the cooling water temperature detected by the cooling water temperature detecting means contains an offset temperature with respect to the actual cooling water temperature, the offset temperature is calculated based on the upper limit temperature or the lower limit temperature,
The detected cooling water temperature is corrected based on the value.
Therefore, the detection accuracy of the cooling water temperature detected by the cooling water temperature detecting means is improved.

[0008]

EXAMPLES The present invention will be described below based on specific examples.

<First Embodiment> FIG. 1 is a schematic view showing the arrangement of an internal combustion engine controller according to the first embodiment of the present invention.

In FIG. 1, 10 is an ECU (Electronic
Control Unit: electronic control device), 20 is a radiator, 3
0 is a water pump, 40 is an internal combustion engine (engine), 5
0 is a thermostat. ECU10 is CPU1
1, a ROM 12 that stores a control program, a RAM 13 that stores various data and is backed up by a battery, and an input / output circuit 14, and a DC power is supplied from a battery B. Output signals from various sensors are input to the ECU 10. These various sensors and output signals are provided in the intake pipe for detecting the engine speed Ne from the engine speed sensor 1 provided in a distributor (not shown) of the internal combustion engine 40 and the load state of the internal combustion engine 40. The intake pipe negative pressure Pm from the pressure sensor 2, the throttle opening TA from a throttle position sensor 3 connected to a throttle valve (not shown), and a thermostat case 41 integrated with the cooling water outlet side of the internal combustion engine 40 are provided. There is a cooling water temperature THWAD from the water temperature sensor 4.

The cooling water in the radiator 20 passes through the inlet hose 21 and is introduced into the internal combustion engine 40 via the water pump 30. Then, when the temperature of the cooling water of the internal combustion engine 40 rises and reaches a predetermined temperature, the thermostat case 4
The thermostat 50 arranged in the unit 1 allows the cooling water to pass through by changing its water passage from the closed state to the open state. Then, the cooling water in the internal combustion engine 40 is returned to the radiator 20 through the thermostat 50 and the outlet hose 22 by the discharge pressure due to the rotation of the water pump 30. For this reason, when the cooling water temperature starts to drop and reaches a predetermined temperature, the thermostat 50 controls the water passage from the open state to the closed state so that the cooling water temperature in the internal combustion engine 40 falls within the predetermined temperature range.

FIG. 5 is a characteristic diagram showing the transition of the cooling water temperature during warming up and completion of warming up. As can be seen from this figure, the thermostat 50 has a valve opening temperature generally set at 82 ° C. with relatively high accuracy, and the valve closing temperature is also set in the same manner. This is because the high temperature side avoids overheating of the internal combustion engine 40, and the low temperature side causes deterioration of fuel efficiency. During warming up, the thermostat 50 is kept closed and the temperature of the cooling water continues to rise. When it reaches 82 ° C, warming up is completed, and in the wax type, the valve is pushed up by the expansion of the wax enclosed and the water channel is The closed state is changed to the open state. Then, the cooling water temperature starts to decrease, and when the cooling water temperature reaches a predetermined temperature (for example, 72 ° C.), the water passage of the thermostat 50 is changed from the open state to the closed state again, and the circulation of the cooling water is stopped to cool the cooling water. The water temperature goes up. In this way, the cooling water temperature after completion of warm-up is 8
The transition will be in the range of 2 ° C to 72 ° C.

Here, the water temperature sensor 4 arranged in the thermostat case 41 integrated with the cooling water outlet side of the internal combustion engine 40 has the thermistor characteristics as shown in FIG. 4, that is, for example, a high temperature region. In the cooling water temperature range Tc to Td with respect to the resistance value R2, the sensor having a large variation between the sensors is used. Then, even if the output signal based on the resistance value corresponding to the cooling water temperature from the water temperature sensor 4 is read as it is, various adaptive control of the internal combustion engine with high accuracy cannot be achieved.

Therefore, the cooling water temperature correction is executed for the cooling water temperature THWAD read from the water temperature sensor 4 as follows. FIG. 2 is a flow chart showing a cooling water temperature correction procedure of the CPU 11 used in the internal combustion engine control device according to the embodiment of the present invention.

In step S101, various sensor signals are read in order to grasp the operating conditions of the internal combustion engine in the internal combustion engine controller. The various sensor signals include the engine speed Ne from the engine speed sensor 1, the intake pipe negative pressure Pm from the pressure sensor 2 for detecting the load condition of the internal combustion engine, and the throttle opening TA from the throttle position sensor 3. , Cooling water temperature THWAD from the water temperature sensor 4
Etc.

Next, in step S102, the RAM
Water temperature sensor correction value THWCA from the storage area of 13
Lold is read.

Next, the routine proceeds to step S103, where it is judged if the operating conditions of the internal combustion engine for water temperature correction are satisfied. That is, the output signal THWAD from the water temperature sensor 4
If the value is equal to or higher than a predetermined value (for example, 60 ° C. or higher), the operating condition of the internal combustion engine is stable (for example, the condition that the engine is operating for a predetermined time or more at the time of idling, the change in the engine speed, or the internal combustion engine It is determined whether or not the change in the load state is in a steady operation below a predetermined value. When the operating condition of the internal combustion engine in step S103 is satisfied, step S1
The routine proceeds to 04, where it is determined whether the water temperature correction condition is satisfied. The water temperature correction condition is, for example, the output signal TH from the water temperature sensor 4 when the thermostat 50 is opened and closed.
Whether or not the inflection point of WAD has been recognized a predetermined number of times or more is used.

When the water temperature sensor correction condition is satisfied in step S104, the process proceeds to step S105, and the current water temperature sensor correction value THWCALnew is calculated. This water temperature sensor correction value THWCALnew is, as shown in FIG. 3, the offset value at this time obtained by subtracting the reading THWS at the inflection point of the output signal THWAD from the water temperature sensor 4 from the thermostat open preset temperature THWSS of the thermostat 50. Is.

Next, in step S106, the control water temperature value THW used for controlling the internal combustion engine is calculated by adding the water temperature sensor correction value THWCALnew calculated in step S105 to the output signal THWAD value from the water temperature sensor 4. It Then, the process proceeds to step S107, the value of the current water temperature sensor correction value THWCALnew is stored in the storage area of the RAM 13 as the water temperature sensor correction value THWCALold, and this program ends.

If the condition of step S103 or step S104 is not satisfied, step S10 is executed.
Control water temperature value THW used for internal combustion engine control
Is the output signal THWAD value from the water temperature sensor 4 and the previous water temperature sensor correction value THWC read in step S102.
Calculated by adding ALold. That is, in this case,
Since the condition for water temperature correction is not satisfied, the correction for the cooling water temperature used for controlling the internal combustion engine is executed using the previous water temperature sensor correction value THWCALold.

The control water temperature value THW calculated in this way
Based on the above, various adaptive controls such as the fuel injection amount correction for the injector 100 and the ignition timing correction for the ignition coil 200, which are well known, are more appropriately executed.

As described above, the internal combustion engine control apparatus of the first embodiment of the present invention detects the cooling water temperature in the internal combustion engine control apparatus that executes various adaptive controls based on the cooling water temperature of the internal combustion engine 40. After the cooling water temperature detecting means including the water temperature sensor 4 and the cooling water temperature reaches a preset specific temperature, a transition is made within a preset temperature range in which the specific temperature is the upper limit temperature. The cooling water temperature control means including the thermostat 50 for controlling the temperature and the cooling water temperature detected by the cooling water temperature detection means are corrected based on the upper limit temperature or the lower limit temperature of the predetermined temperature range in the cooling water temperature control means. CP in the ECU 10
The cooling water temperature correction means achieved in U11 is provided.

Therefore, after the cooling water temperature reaches the preset specific temperature and transitions within the predetermined temperature range, the detected cooling water temperature is based on the upper limit temperature or the lower limit temperature of the predetermined temperature range. It is corrected to the actual cooling water temperature.

Therefore, even if a cooling water temperature range corresponding to a predetermined resistance value is wide and the water temperature sensors have a large variation and the accuracy is not good, the accuracy is ensured by the correction in carrying out various adaptive controls. Therefore, no inconvenience will occur. That is, it is possible to construct a low-cost internal combustion engine control device using an inexpensive water temperature sensor.

<Second Embodiment> FIG. 6 is a schematic view showing the arrangement of an internal combustion engine controller according to the second embodiment of the present invention.
It should be noted that the same reference numerals and symbols are given to those having the same configurations or corresponding portions as those of the above-described first embodiment, and detailed description thereof will be omitted.

A cooling fan switch 51 is provided in a thermostat case 41 integrated with the cooling water outlet side of the internal combustion engine 40.
Is provided. As shown in the characteristic diagram of FIG. 7, the cooling fan switch 51 is turned on when the cooling water temperature rises and reaches an upper limit temperature (for example, 93 ° C.) which is a specific temperature.
When the temperature falls and reaches the lower limit temperature (for example, 88 ° C.), it becomes OFF. ON / OFF of the cooling fan switch 51
The cooling fan relay 52 is turned on / off in synchronization with the above, and the cooling fan 53 arranged near the radiator 20 is rotated / turned on / off.
After the stoppage is repeated and the cooling water temperature of the internal combustion engine 40 once reaches the upper limit temperature, a predetermined temperature range (in the present embodiment,
88-93 ° C). That is, in the present embodiment, the temperature of the cooling water of the internal combustion engine 40 rises, the thermostat 50 exceeds the controllable cooling water temperature in the normally open state, and further, the cooling fan 53 assists in lowering the cooling water temperature. The structure when it is necessary is shown.

Here, the water temperature sensor 4 in the present embodiment is arranged in a thermostat case 41 which is integral with the cooling water outlet side of the internal combustion engine 40, as in the first embodiment described above. A material having the thermistor characteristics as shown is used. That is, also in this case, even if the output signal based on the resistance value corresponding to the cooling water temperature from the water temperature sensor 4 is read as it is, it is not possible to achieve highly accurate various adaptive control of the internal combustion engine.

Therefore, the cooling water temperature correction is executed for the cooling water temperature THWAD read from the water temperature sensor 4 as follows.

In the cooling water temperature correction control in the above-described first embodiment, an offset value which is a temperature difference is calculated using the inflection point of the water temperature sensor reading THWAD when the thermostat 50 changes from the closed state to the open state. There is. On the other hand, in the present embodiment, since the upper limit temperature (93 ° C.) of the predetermined temperature range in which the cooling fan switch 51 is ON or the lower limit temperature (88 ° C.) in which the cooling fan switch 51 is OFF is managed with high accuracy,
Water temperature sensor reading THWAD due to rotation of the cooling fan 53
Of the water temperature sensor reading value THWAD caused by the inflection point of the cooling fan 53 or the stop of the cooling fan 53, or both timings, or using the water temperature sensor reading value THWAD when the cooling fan 53 is ON or OFF Temperature correction can be performed.

As described above, the internal combustion engine control system of the second embodiment of the present invention detects the cooling water temperature in the internal combustion engine control system which executes various adaptive controls based on the cooling water temperature of the internal combustion engine 40. After the cooling water temperature detecting means including the water temperature sensor 4 and the cooling water temperature reaches a preset specific temperature, a transition is made within a preset temperature range in which the specific temperature is the upper limit temperature. Cooling water temperature control means including a cooling fan switch 51, a cooling fan relay 52, and a cooling fan 53, and the cooling water temperature detected by the cooling water temperature detection means, the predetermined temperature in the cooling water temperature control means. CPU 11 in ECU 10 for correction based on the upper limit temperature or lower limit temperature of the range
And a cooling water temperature correction means.

Therefore, after the cooling water temperature reaches the preset specific temperature and transitions within the predetermined temperature range, the detected cooling water temperature is based on the upper limit temperature or the lower limit temperature of the predetermined temperature range. It is corrected to the actual cooling water temperature.

Therefore, even if a cooling water temperature range corresponding to a predetermined resistance value is wide and the water temperature sensors have a large variation and the accuracy is not good, the accuracy is ensured by the correction in carrying out various adaptive controls. Therefore, no inconvenience will occur. That is, it is possible to construct a low-cost internal combustion engine control device using an inexpensive water temperature sensor.

As described above, the cooling water temperature control means in the first embodiment is the thermostat 50, and the cooling water temperature control means in the second embodiment is the cooling fan switch 51, the cooling fan relay 52 and the cooling fan 53. However, when the present invention is carried out, the present invention is not limited to this, and after the cooling water temperature reaches the preset specific temperature, the preset predetermined temperature with the specific temperature as the upper limit temperature is set. Any control may be used as long as the transition is controlled within the temperature range.

[0034]

As described above, the internal combustion engine control device of the present invention performs various adaptive controls based on the cooling water temperature of the internal combustion engine, and the cooling water temperature detected by the cooling water temperature detecting means. After reaching a preset specific temperature, cooling water temperature control means for controlling the specific temperature to transition within a preset temperature range having an upper limit temperature, and the detected cooling water temperature Is provided with a cooling water temperature correction means for correcting the temperature based on the upper limit temperature or the lower limit temperature of the predetermined temperature range, and the detected cooling water temperature has an offset value from the actual cooling water temperature and the accuracy is not good. However, the temperature of the cooling water is corrected based on the upper limit temperature or the lower limit temperature of the predetermined temperature range set in advance to ensure its accuracy. As a result, an inexpensive sensor or the like for detecting the cooling water temperature can be adopted, and the internal combustion engine control device can be constructed at low cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of an internal combustion engine controller according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure of a CPU used in an internal combustion engine control apparatus according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of temperature correction in the internal combustion engine controller according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a variation in cooling water temperature with respect to a resistance value detected by a water temperature sensor used in the internal combustion engine controller according to the first embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a transition of cooling water temperature due to opening and closing of a thermostat used in an internal combustion engine controller according to a conventional example and a first example of the present invention.

FIG. 6 is a schematic diagram showing a configuration of an internal combustion engine controller according to a second embodiment of the present invention.

FIG. 7 is a cooling fan ON / OF used in a conventional internal combustion engine controller and a second embodiment of the present invention.
It is a characteristic view which shows the transition of the cooling water temperature by F.

FIG. 8 is a characteristic diagram showing a variation in cooling water temperature with respect to a resistance value detected by a water temperature sensor used in a conventional internal combustion engine controller.

[Explanation of symbols]

 4 Water Temperature Sensor 10 ECU 20 Radiator 40 Internal Combustion Engine (Engine) 50 Thermostat 51 Cooling Fan Switch 52 Cooling Fan Relay 53 Cooling Fan

Claims (1)

[Claims] 1. An internal combustion engine control device for performing various adaptive controls based on a cooling water temperature of an internal combustion engine, comprising: a cooling water temperature detecting means for detecting the cooling water temperature; After reaching the temperature, cooling water temperature control means for controlling the temperature to transition within a preset temperature range with the specific temperature as the upper limit temperature, and the cooling water detected by the cooling water temperature detection means. An internal combustion engine control device comprising: a cooling water temperature correction means for correcting the water temperature based on an upper limit temperature or a lower limit temperature of the predetermined temperature range in the cooling water temperature control means.