JP2001020800A - Monitoring system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to start controlling and diagnosing an internal combustion engine reliably avoiding influence of variation by products such as a thermostat and water temperature sensor. SOLUTION: A monitoring system 51 is provided with a timer counter 52, which starts counting when a cooling water temperature Tw reaches a judgement cooling water temperature Tcs after an engine is started. Tcs is a predetermined temperature proceeding to an equilibrium temperature after the engine is warmed up. The monitoring system 51 varies an increment of counts of the timer counter 52 depending on engine operating condition and transmits a command signal to a control unit 61 and diagnostic unit 71 for starting control and diagnosis when the count numbers reach predetermined values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitoring device for an internal combustion engine, and more particularly to a monitoring device for an internal combustion engine that determines when to activate a control device and a diagnostic device of the engine based on a cooling water temperature of the internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine such as an automobile engine, generally, when starting, for example, the timing at which control such as electronic fuel injection control and various diagnostics are started is performed after a warm-up operation in which the starting state of the engine is stabilized. It has been. The determination of the timing is often made based on monitoring of the cooling water temperature of the internal combustion engine, and when the monitored cooling water temperature reaches the equilibrium temperature after the engine is warmed up. As such an example, a "control device for an internal combustion engine" described in, for example, JP-A-7-71304 is known. In this device, the timing at which the air-fuel ratio feedback control (electronic fuel injection control) of the automobile engine is started is made variable in accordance with the cooling water temperature at the time of starting the engine, so that it is more desirable according to the actual warm-up mode of the engine. The start timing of the air-fuel ratio feedback control is obtained.

In general, in an internal combustion engine such as an automobile engine, adjustment of the engine cooling water temperature at the time of starting or the like is performed by a thermostat provided in a cooling water passage of the engine. The thermostat is a passage opening / closing valve that switches between an open state and a closed state at a specific temperature, and opens and closes a circulation path of cooling water in order to adjust an engine to an appropriate temperature. That is, when the cooling water temperature is lower than a predetermined value (for example, 85 ° C.) corresponding to the equilibrium temperature after the warming-up operation, the thermostat closes the valve and circulates the cooling water inside the engine. Acts to raise the cooling water temperature.On the other hand, when the cooling water temperature becomes higher than the predetermined value, the valve is opened, and the cooling water is circulated between the engine and the radiator so that the cooling water temperature is the same as the predetermined value. It is adjusted to be near. At this time, the cooling water temperature is detected by a water temperature sensor provided in a water jacket of the engine, and active commands to various control devices and diagnostic devices are issued based on the detection value of the water temperature sensor.

[0004]

By the way, the thermostat and the water temperature sensor usually have a product variation. As a result, the cooling water temperature adjusted by the thermostat and the cooling water temperature detected by the water temperature sensor are caused. The values will also vary. For example, as shown in FIG. 5, even when a thermostat adjusted to correspond to the above-mentioned predetermined equilibrium temperature is used, a temperature at which equilibrium actually occurs due to product variation, that is, a water temperature sensor is used. The detected equilibrium temperature Twd may vary by ± ΔT. In addition, such variations exist in the water temperature sensor itself, and the actual temperature (water temperature) may be slightly different from the detected temperature.

Therefore, the cooling water temperature Tw is set as a criterion for starting the control and diagnosis of the internal combustion engine.
In the case where the value of s is set close to the equilibrium temperature, for example, as shown in FIG. 5, within the above-mentioned temperature variation ± ΔT of the equilibrium temperature Twd, the equilibrium is established through the thermostat. The adjusted water temperature value may not reach the reference water temperature Tws, or the water temperature sensor may not detect that the water temperature reaches the reference water temperature Tws.

That is, as shown in FIG. 6, for example, the above-mentioned equilibrium temperature Twd should originally have a transition shown as a solid line L1, but due to the above-mentioned variation of the thermostat, actually has a transition shown as a broken line L2. In such a case, even if the water temperature sensor is normal, the detected temperature is only Twd ′ (<Tws),
It becomes impossible to detect the arrival at the determination reference water temperature Tws. Further, at this time, if the water temperature sensor itself also has a variation in the detected temperature on the negative side, it is more difficult to detect the water temperature sensor reaching the criterion water temperature Tws. In such a case, the time t shown in FIG.
The control and diagnosis of the engine should be started at s, but even the start is unclear.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reliably start control and diagnosis of an internal combustion engine without depending on product variations of a thermostat or a water temperature sensor. It is an object of the present invention to provide a monitoring device for an internal combustion engine that can be used.

[0008]

The means for achieving the above object and the effects thereof will be described below. In order to achieve the above object, the invention according to claim 1 monitors a cooling water temperature of an internal combustion engine, and determines an active time of at least one of a control device and a diagnostic device of the engine based on the monitored cooling water temperature. A monitoring device for the internal combustion engine, wherein the cooling water temperature becomes a predetermined water temperature before reaching an equilibrium temperature after the engine is warmed up, and after a predetermined period, at least one of the control device and the diagnosis device. The gist of the present invention is to provide forcible active means for forcibly making this active.

According to this configuration, the forcible active means is configured such that the cooling water temperature becomes a predetermined water temperature before reaching the equilibrium temperature after the engine is warmed up, and after a predetermined period, the control device and the diagnosis device Forcibly activate at least one of them. Therefore, by appropriately setting the predetermined water temperature, for example, setting the predetermined water temperature to a value equal to or less than the lower limit value of the variation of the equilibrium temperature, the control of the internal combustion engine can be reliably performed without being affected by the product variation of the thermostat and the water temperature sensor. And the diagnosis can be started.

According to a second aspect of the present invention, in the monitoring apparatus for an internal combustion engine according to the first aspect, the forcibly active means includes:
A timer counter, and instructs the timer counter to start counting based on a predetermined water temperature before the temperature reaches the equilibrium temperature. When the count number of the timer counter reaches a predetermined value, the control device and the diagnostics are started. The gist of the invention is that at least one of the devices is forcibly activated.

According to this configuration, based on the fact that the cooling water temperature becomes a predetermined water temperature before reaching the equilibrium temperature after the engine is warmed up, at least one of the control device and the diagnostic device is forcibly issued after a predetermined period. It is possible to easily and suitably configure the compulsory active means for making this active.

According to a third aspect of the present invention, in the monitoring apparatus for an internal combustion engine according to the second aspect, the forcibly active means includes:
The gist of the present invention is that the increment of the count of the timer counter is made variable in accordance with the operating state of the internal combustion engine.

[0013] According to this configuration, the difference in the rise time of the cooling water temperature that occurs according to the operating condition when the internal combustion engine is started is made variable by increasing the count for each count of the timer counter according to the operating condition of the internal combustion engine. By doing so, it can be absorbed. Therefore, the control device or the diagnostic device can be started at a desired time regardless of various operating conditions at the time of starting the internal combustion engine.

According to a fourth aspect of the present invention, in the monitoring apparatus for an internal combustion engine according to the third aspect, the forcible active means is configured to change a count increment of the timer counter for each count according to a load of the internal combustion engine. The main point is to do.

According to this configuration, the time difference of the rise of the cooling water temperature that occurs according to the load at the time of starting the internal combustion engine is made variable by increasing the count for each count of the timer counter according to the load of the internal combustion engine. Be able to absorb. Therefore, the control device or the diagnostic device can be started at a desired time regardless of the magnitude of the load at the time of starting the internal combustion engine.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a monitoring device for an internal combustion engine according to the present invention is applied to an engine system of an automobile will be described below with reference to the drawings.

As shown in FIG. 1, an engine 1 composed of, for example, four cylinders includes a cylinder 3, a piston 4, a crankshaft 5, a connecting rod 6 for connecting the piston 4 and the crankshaft 5, a water jacket 7 surrounding the cylinder 3, A radiator 8, a cooling fan 9, a water pump 10, and the like are provided outside the engine main body and have an internal space communicating with the water jacket 7.

In the combustion chamber 11 of each cylinder 3, the air-fuel mixture explodes and burns, causing the piston 4 to move up and down, and this up-and-down movement is converted into the rotational driving force of the crankshaft 5 via the connecting rod 6. Further, the supply of the air-fuel mixture and the discharge of the combustion gas are performed via an intake / exhaust port (not shown). The water jacket 7 serving as a space for circulating cooling water cools the cylinder head 12 and the cylinder block 13 heated by the explosion and combustion of the air-fuel mixture as necessary, or maintains the cylinder 3 at a constant temperature.
It is configured to surround the outer periphery of. In addition, an air flow meter (not shown) for detecting an intake air amount is provided in an intake passage communicating with the intake port, and a detection signal thereof is sent to a monitoring device 51 described later.

The radiator 8 and the cooling water circulation path of the water jacket 7 are communicated by upper and lower communication passages 14 and 15. A thermostat 16 is provided in the middle of the upper communication passage 14.

The thermostat 16 is, as described above,
A valve that opens and closes mechanically according to the water temperature. When the water temperature is equal to or lower than a predetermined temperature (for example, 85 ° C.), the valve is closed and the communication passage 14 is closed, and when the water temperature exceeds 85 ° C., the valve is opened. Thus, the passage 14 is opened to maintain the cooling water at a predetermined temperature.

A water temperature sensor 41 provided on the inner wall of the water jacket 7 detects the temperature Tw of the cooling water.
The detection signal is sent to the monitoring device 51 or the like. This monitoring device 5
1 monitors the temperature Tw of the cooling water at the time of starting the engine, and determines the active time of the control device 61 for controlling each part of the engine and the diagnostic device 71 for diagnosing each part of the engine based on the monitored temperature Tw; That is, it is a device for instructing the start of the control and the diagnosis, and includes a timer counter 52 and the like.

The control of each part of the engine performed by the control device 61 includes, for example, electronic fuel injection control (EFI) for performing appropriate fuel injection according to the state of the engine 1 and idle speed after engine warm-up. There is control such as idle speed control (ISC) performed by controlling the opening of a control valve (ISCV). In addition, the diagnostic device 7
For example, various types of sensors (for example, a water temperature sensor 41, an intake pressure sensor, an oxygen sensor,
Operation diagnosis of a throttle sensor or the like). In addition to the monitoring device 51, the control device 61 and the diagnostic device 71 are also configured as a computer system having a CPU, a memory, and the like.

Next, the control device 6 by the monitoring device 51
1 and the content of processing relating to the sending of an active command to the diagnostic device 71, that is, the sending of an operation start command will be described with reference to FIGS.

FIG. 2 shows an "operation start command routine" executed by the monitoring device 51. A program related to this routine is stored in a memory in the monitoring device 51 in advance, and is executed every predetermined time after the main power supply of the vehicle is turned “ON”. The main power supply of this car is "O
The time set as "N" is represented as time t0 in the time chart shown in FIG.

Step S1 of this operation start command routine
At 0, the monitoring device 51 first determines whether or not the cooling water temperature Tw has reached the determination cooling water temperature Tcs, which is a predetermined water temperature before reaching the above-described equilibrium temperature after the engine is warmed up. The cooling water temperature Tcs is determined by the timer counter 5
This is a threshold value set in advance to start the counting of 2. The monitoring device 51 determines here that the cooling water temperature Tw has reached the judgment cooling water temperature Tcs, that is, the judgment cooling water temperature Tcs.
If it is determined that this is the case, the process proceeds to step S20.
Move to In FIG. 3, the cooling water temperature Tw
Is reached as a time tc, and the counting operation of the timer counter 52 is started from the time tc as described below (FIG. 3).
(B)). Further, the cooling water temperature Tcs for this determination is shown in FIG.
As shown in (a), the value is set as a value equal to or less than the variation lower limit value (Twd center value-ΔT) of the above-mentioned equilibrium temperature Twd after the engine is warmed up, for example, as a value corresponding to a temperature of about 75 ° C. .

In step S20, the monitoring device 51
Is 1 of the count number CDANKI of the timer counter 52.
The count increase (hereinafter simply referred to as count increase) ΔDANKI for each count is determined as a value corresponding to the intake air amount GA at that time.

The relationship between the count increase .DELTA.DANKI and the intake air amount GA is, for example, such that the count increase .DELTA.DANKI increases as the intake air amount GA increases, as shown in FIG. Is stored in a memory or the like. Further, the intake air amount GA is calculated based on the output of the air flow meter.

Here, the count increase amount ΔDANKI is increased with the increase in the intake air amount GA because the intake air amount G
This is because the increase in A means an increase in the engine load, and the increase in the cooling water temperature Tw is accelerated with the increase in the engine load. Therefore, in this embodiment, the timer counter 52 shown in FIG.
Is shortened. That is, in this embodiment, the count increment ΔDANKI is variably set in accordance with the rising speed of the cooling water temperature Tw.

In the following step S30, the monitoring device 5
1 is the previous count number CDANKI and the count increment number Δ
DANKI is added and a new count number CDANKI is added.
And That is, the monitoring device 51 determines in step S3
In the first process of 0, the counting operation of the timer counter 52 is started, and in the subsequent repetition process,
The count number CDANKI is increased by a count increase ΔDANK.
Count up by I minutes.

On the other hand, if it is determined in step S10 that the cooling water temperature Tw is lower than the determination cooling water temperature Tcs, the process proceeds to step S40, and the count number CDANKI is set to "0".

In the following step S50, the monitoring device 5
1 means that the count number CDANKI is equal to the predetermined count value Cth
It is determined whether or not has been reached. Where the count number CDAN
If it is determined that KI has reached the predetermined count value Cth, the process proceeds to step S60. Here, when the count number CDANKI reaches this value (time ts in FIG. 3), the predetermined count value Cth is the cooling water temperature Tw.
Is determined in advance by an experiment or the like as a value at which a desired equilibrium temperature (Twd) has been reached. On the other hand, the same step S50
When it is determined that the count number CDANKI has not yet reached the predetermined count value Cth, the process is temporarily terminated.

In step S60, the monitoring device 51 transmits a start command signal ST for instructing the control device 61 and the diagnosis device 71 to start the control and the diagnosis at a time ts shown in FIG. Accordingly, the control device 61 and the diagnosis device 71 start the control and the diagnosis, respectively.

As described above, in the present embodiment, when the cooling water temperature Tw reaches the judgment cooling water temperature Tcs (at time t).
c) The counting of the timer counter 52 is started, and when the count number CDANKI of the timer counter 52 reaches a predetermined count value Cth, the control device 61 and the diagnostic device 7
1 to start a control command and a diagnosis. Therefore, the thermostat 16 and the water temperature sensor 41 are not affected by product variations.

The count increment .DELTA.DANKI of the timer counter 52 according to the engine load (intake air amount GA).
, Ie, by making the count period τ variable, the start command signal ST
The transmission time ts can be made suitable according to the load state at the time of starting the engine.

As described above, according to the monitoring apparatus for an internal combustion engine of the present embodiment, the following effects can be obtained. (1) In the present embodiment, the engine control device 6
1 and the time ts at which the start command signal ST is transmitted to the diagnosis device 71, the cooling water temperature Tw is determined to be the cooling water temperature Tcs.
Timer counter 5 that started counting when it reached
It is assumed that the count number CDANKI of 2 has reached the predetermined count value Cth. Therefore, the control and diagnosis of the devices 61 and 71 can be started without being affected by the variation of the equilibrium temperature Twd caused by the product variation of the thermostat 16 and the water temperature sensor 41.

(2) In the present embodiment, the count period τ is varied by variably setting the count increase ΔDANKI of the timer counter 52 according to the engine load (intake air amount GA). Therefore, the transmission time ts of the start command signal ST can be made suitable according to the load state at the time of starting the engine.

The embodiment of the present invention described above can be implemented by changing its configuration as follows. In the above-described embodiment, an example in which the monitoring device 51, the control device 61, and the diagnostic device 71 are configured as individual computer systems has been described. However, the present invention is not limited thereto, and these devices may be configured as one computer system sharing a CPU and the like. It may be configured.

In the above embodiment, the count increment ΔDANKI is changed according to the intake air amount GA. However, the present invention is not limited to this. Count increase ΔDAN
KI may be changed according to, for example, the engine speed, or may be changed according to the intake air amount GA and the engine speed. In short, what is necessary is just to change the count increment ΔDANKI according to the engine load.

The count increase .DELTA.DANKI is not limited to being changed according to the engine load. The increase .DELTA.DANKI is, for example, the cooling water temperature Tw at the time of engine start.
And may be changed according to the outside temperature, etc.,
In short, it is only necessary to change it according to the operating state of the engine. Further, the count increase ΔDANKI may be constant without changing according to the operating state of the engine.

As means for forcibly activating the control device and the diagnostic device of the internal combustion engine, instead of the timer counter,
A configuration using a delay circuit or the like may be employed. That is, in this case, the detection signal of the determination cooling water temperature Tcs is appropriately delayed to be a signal that forcibly activates the control device or the diagnostic device.

Also, in this case, the engine load, etc.
The delay amount (delay time) can be made variable according to the operating state of the engine. In the above-described embodiment, the target to be forcibly activated is the control device and the diagnostic device of the internal combustion engine, but the present invention is not limited to this, and the target to be forcibly activated is at least one of the control device and the diagnostic device. Should be fine.

Other technical ideas grasped from the above embodiment will be described below together with their effects. (1) The monitoring device for an internal combustion engine according to claim 4,
A monitoring device for an internal combustion engine, wherein the increment of the timer counter for each count is made variable in accordance with the intake air amount of the internal combustion engine. According to this configuration, the intake air amount of the internal combustion engine can be suitably used as the load information of the internal combustion engine.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an engine system to which an internal combustion engine monitoring device according to the present invention is applied.

FIG. 2 is a flowchart showing an operation start command procedure executed by the monitoring device.

FIG. 3 is a time chart showing an example of a processing mode of the monitoring device.

FIG. 4 is a graph showing a relationship between an intake air amount and a count increase.

FIG. 5 is an explanatory diagram showing a relationship between a variation distribution of an equilibrium temperature and a start determination temperature.

FIG. 6 is a time chart showing an example of variation in detection of a cooling water temperature after warm-up.

[Explanation of symbols]

1 ... Engine, 2 ... Cooling system, 3 ... Cylinder, 4 ...
Piston, 5 ... crankshaft, 6 ... connecting rod, 7
... water jacket, 8 ... radiator, 9 ... cooling fan, 10 ... water pump, 11 ... combustion chamber, 12 ... cylinder head, 13 ... cylinder block, 16 ... thermostat, 41 ... water temperature sensor, 51 ... monitoring device, 52 ... timer Counter, 61 ... Control device, 71 ... Diagnosis device.

Claims (4)

[Claims] 1. A monitoring device for an internal combustion engine that monitors a cooling water temperature of an internal combustion engine and determines an active time of at least one of a control device and a diagnostic device of the engine based on the monitored cooling water temperature, Forced active means for forcibly activating at least one of the control device and the diagnostic device after a predetermined period based on the fact that the water temperature becomes a predetermined water temperature before reaching the equilibrium temperature after the engine is warmed up. A monitoring device for an internal combustion engine, comprising: 2. The monitoring device for an internal combustion engine according to claim 1, wherein said forced active means includes a timer counter, and said timer counter counts based on a predetermined water temperature before the temperature reaches the equilibrium temperature. 2. When the count of the timer counter reaches a predetermined value, at least one of the control device and the diagnostic device is forcibly activated. 2. A monitoring device for an internal combustion engine according to claim 1. 3. The monitoring device for an internal combustion engine according to claim 2, wherein said forced active means changes a count increment of said timer counter for each count according to an operation state of the internal combustion engine. 4. The monitoring apparatus for an internal combustion engine according to claim 3, wherein said forced active means changes the increment of the timer counter for each count according to the load of the internal combustion engine.