JPH0968082A - Fuel injection quantity control device of diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimally control a fuel injection quantity of a diesel engine so that actual torque of the engine coincides with demand torque. SOLUTION: Combustion pressure acting on a glow plug or a fuel injection nozzle is detected by a combustion pressure sensor, and actual torque Ta of an engine is calculated (S1) on the basis of this. Demand torque Tt is calculated (S2) on the basis of an accelerator stepping quantity AC and engine rotating speed NE. A fuel injection quantity is controlled (S3 to S6) by making a feedback process so that the actual torque Ta coincides with the demand torque Tt. Or a map to be used to set the fuel injection quantity is rewritten so that the actual torque Ta coincides with the demand torque Tt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device for a diesel engine.

[0002]

2. Description of the Related Art As is well known, a conventional distributed fuel injection pump for a diesel engine has a control sleeve as a fuel injection amount adjusting member, and the fuel injection amount varies depending on the moving position of the control sleeve. It is supposed to be adjusted. In addition, with the recent shift to electrification, the control of the fuel injection amount determines the fuel injection amount by referring to the map from the accelerator depression amount and the engine speed, and outputs a signal corresponding to this fuel injection amount. To drive a DC motor or a step motor as an electronic governor,
This controls the position of the control sleeve to control the fuel injection amount by the fuel injection pump.

[0003]

However, in such a conventional fuel injection amount control device for a diesel engine, the fuel injection amount adjusting mechanism (mechanical portion) of the fuel injection pump may suffer from component variations and durability deterioration. There is a problem that a desired fuel injection amount cannot be obtained, which leads to deterioration of drivability and fuel efficiency, deterioration of exhaust gas, and generation of black smoke.

Further, even if the fuel injection pump is normal, there is a problem that a desired fuel injection amount cannot be obtained due to clogging of the fuel injection nozzle, deterioration of the engine body, and the like. In view of such conventional problems, the present invention provides a fuel injection amount control device for a diesel engine that can always obtain optimum characteristics regardless of variations in parts of the fuel injection pump, fuel injection nozzle, engine body, and deterioration of durability. The purpose is to provide.

[0005]

Therefore, in the invention according to claim 1, as shown in FIG. 1A, the combustion pressure detecting means for detecting the combustion pressure in the cylinder of the diesel engine is detected. Actual torque calculating means for calculating the actual torque of the engine based on the combustion pressure, required torque calculating means for calculating the required torque of the engine based on the engine operating conditions, and fuel so that the actual torque matches the required torque. A fuel injection amount feedback control means for feedback controlling the fuel injection amount by the injection pump is provided to constitute a fuel injection amount control device for a diesel engine.

That is, the combustion pressure in the cylinder is detected, and the actual torque of the engine is calculated based on this. Then, the fuel injection amount by the fuel injection pump is feedback-controlled so that the actual torque matches the required torque calculated based on the engine operating conditions. By such feedback control of the fuel injection amount, the required torque can always be obtained.

According to the second aspect of the invention, as shown in FIG. 1 (b), the fuel injection amount storage means for storing the fuel injection amount corresponding to the engine operating condition, and the actual engine operation from this storage means. Fuel injection amount retrieval means for retrieving the fuel injection amount corresponding to the condition, and fuel injection amount signal output for controlling the fuel injection amount by the fuel injection pump by outputting a signal corresponding to the fuel injection amount retrieved by this retrieval means. In a fuel injection amount control device for a diesel engine, the combustion pressure detecting means for detecting a combustion pressure in a cylinder of the diesel engine, and an actual torque calculating means for calculating an actual torque of the engine based on the detected combustion pressure. When,
A required torque calculation unit that calculates a required torque of the engine based on the engine operating condition, and a stored value of the fuel injection amount for each engine operating condition of the fuel injection amount storage unit so that the actual torque matches the required torque. A storage value rewriting means for rewriting is provided.

That is, a fuel injection amount storage means (map) in which the fuel injection amount is stored in correspondence with the engine operating condition.
Is used to control the fuel injection amount, but this map is rewritable and rewritten by learning. In learning, the combustion pressure in the cylinder is detected, and the actual torque of the engine is calculated based on this. Then, the stored value of the fuel injection amount for each engine operating condition on the map is rewritten so that this actual torque matches the required torque calculated based on the engine operating condition.

By rewriting the map by such learning, the required torque can always be obtained. The invention according to claim 3 is characterized in that the required torque calculating means calculates the required torque of the engine based on at least the accelerator depression amount.

In the invention according to claim 4, particularly in the case of the invention according to claim 2, the demanded torque calculation means determines the demanded torque of the engine on the basis of the fuel injection amount retrieved by the fuel injection amount retrieval means. Is calculated. The invention according to claim 5 is characterized in that the combustion pressure detecting means is a piezoelectric sensor provided at a position for receiving the combustion pressure acting on the glow plug.

According to a sixth aspect of the invention, the combustion pressure detecting means is a piezoelectric sensor provided at a position for receiving the combustion pressure acting on the fuel injection nozzle.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. First, a first embodiment will be described. FIG. 2 shows the system configuration. The diesel engine 1 includes a distributed fuel injection pump 2. In the distributed fuel injection pump 2, the fuel injection amount is adjusted by controlling the DC motor (or step motor) 3 for adjusting the fuel injection amount,
The adjusted amount of high pressure fuel is delivered to the fuel injection nozzle 4 to inject fuel into the cylinder. Then, the fuel is compression ignited in the cylinder and burned. It should be noted that the ignition is assisted by being heated by the glow plug 5 as necessary at the time of starting.

According to the structure of the present invention, the glow plug 5 has a screw-type mounting portion as combustion pressure detecting means.
A combustion pressure sensor (piezoelectric sensor) 6 composed of a piezoelectric element is provided on the mounting washer so as to detect the combustion pressure P acting on the glow plug 5. As a combustion pressure detecting means, a combustion pressure sensor (piezoelectric sensor) 6'comprising a piezoelectric element is provided in the form of a mounting washer on the screw-in type mounting portion of the fuel injection nozzle 4, and the combustion acting on the fuel injection nozzle 4 The pressure P may be detected.

Further, a crank angle sensor 7 which outputs a pulse signal in synchronization with the crank angle is provided, whereby the crank angle can be detected and the engine speed NE can be calculated. Further, a potentiometer-type accelerator sensor 8 is provided to detect the accelerator depression amount AC.

The signals of these sensors 6 to 8 are input to the control unit 9. The control unit 9 controls the DC motor 3 for adjusting the fuel injection amount by executing the fuel injection amount control routine of FIG. 3 by the built-in microcomputer at predetermined time intervals or at predetermined crank angle intervals. Control the injection amount. The fuel injection amount control routine of FIG. 3 will be described.

In step 1 (denoted as S1 in the drawing; the same applies hereinafter), the actual torque Ta of the engine is calculated based on the combustion pressure P detected based on the signal from the combustion pressure sensor 6. This portion corresponds to the actual torque calculating means. However, the actual calculation is performed by another routine. That is, while monitoring the crank angle based on the signal from the crank angle sensor 7, the signal from the combustion pressure sensor 6 is sent at predetermined sampling timings from the predetermined integration start crank angle to the integration end crank angle. At the same time as the combustion pressure P is read after A / D conversion, its integrated value ΣP = Σ
Calculate P + P. Then, the integrated value ΣP from the integration start crank angle to the integration end crank angle is stored and held as the indicated average effective pressure Pi. Then, as the product of the indicated average effective pressure Pi and the constant K, the actual torque Ta = K · Pi
Is calculated.

In step 2, as the engine operating conditions, the accelerator pedal depression amount AC detected based on the signal from the accelerator sensor 8 and the engine speed NE calculated based on the signal from the crank angle sensor 7 are read. From these, the required torque Tt of the engine is searched by referring to the map. This part corresponds to the required torque calculation means.

In step 3, the actual torque Ta and the required torque Tt are compared. As a result of the comparison, when Ta <Tt, the routine proceeds to step 4, where the fuel injection amount is increased so that Ta = Tt. Conversely, when Ta> Tt, the routine proceeds to step 5, where the fuel injection amount is reduced so that Ta = Tt.

When Ta = Tt, the fuel injection amount is maintained at the present value. After that, in step 6, a fuel injection amount signal is output to the DC motor 3 based on the fuel injection amount adjusted to be increased or decreased. Here, steps 3 to 6 correspond to the fuel injection amount feedback control means.

By controlling the fuel injection amount in this way, the actual torque of the engine can always be controlled to the required torque. Next, a second embodiment will be described. The system configuration is the same as that of FIG. 2 except that the microcomputer in the control unit 9 executes the fuel injection amount control routine of FIG. 4 and the learning routine of FIG.

As the fuel injection amount storage means, a map in which the fuel injection amount is stored corresponding to the engine operating condition, specifically, the operating region determined by the accelerator pedal depression amount AC and the engine speed NE is used. However, this map is provided in RAM so that it can be rewritten.
For AM, a backup power supply is used to retain the stored contents even when the engine is stopped.

The fuel injection amount control routine of FIG. 4 will be described. In step 11, as the actual engine operating conditions, the accelerator depression amount AC detected based on the signal from the accelerator sensor 8 and the engine speed NE calculated based on the signal from the crank angle sensor 7 are read, From these, the fuel injection amount is searched with reference to the map. This portion corresponds to the fuel injection amount search means.

In step 12, a fuel injection amount signal is output to the DC motor 3 based on the retrieved fuel injection amount. This portion corresponds to the fuel injection amount signal output means.
The learning routine of FIG. 5 will be described. In step 21, the actual torque Ta of the engine is calculated based on the combustion pressure P detected based on the signal from the combustion pressure sensor 6. This portion corresponds to the actual torque calculating means.

However, the actual calculation is performed by another routine as described in step 1 of FIG. Step 22
Then, as the engine operating condition, the current fuel injection amount (the fuel injection amount retrieved in step 11 of FIG. 4) is read, and the required torque Tt of the engine is calculated by referring to the conversion table. This part corresponds to the required torque calculation means.

In step 23, the actual torque Ta and the required torque Tt are compared. As a result of the comparison, when Ta <Tt, the routine proceeds to step 24, where the fuel injection amount is learned so that Ta = Tt. That is, the fuel injection amount (map value) in the current operating region is increased. Conversely, Ta> Tt
In the case of, the routine proceeds to step 25, and the fuel injection amount is learned so that Ta = Tt. That is, the fuel injection amount (map value) in the current operating region is reduced.

When Ta = Tt, the fuel injection amount (map value) is maintained at the current value. After that, in step 26, the stored value (map value) of the fuel injection amount for each operation region on the map is rewritten based on the learning result. Here, steps 23 to 26 correspond to the stored value rewriting means. By rewriting the fuel injection amount search map by such learning, the actual torque of the engine can always be controlled to the required torque.

As a map for searching the fuel injection amount, a first map on the ROM storing the initial value of the fuel injection amount and a second map on the RAM storing the learning correction coefficient are provided, and the fuel injection amount is set. Even if the fuel injection amount is set by the product of the initial value of the amount and the learning correction coefficient, the learning correction coefficient on the second map may be rewritten so that the actual torque matches the required torque. Good.

[0028]

As described above, according to the first aspect of the invention, the actual torque of the engine is calculated from the combustion pressure in the cylinder of the diesel engine, and this is in agreement with the required torque determined by the engine operating conditions. Since the fuel injection amount is feedback-controlled in this way, the required torque can always be obtained regardless of variations in parts of the fuel injection pump, fuel injection nozzle, and engine body, and deterioration of durability, improving drivability and improving fuel efficiency. The effect of reducing exhaust gas and black smoke can be obtained.

According to the second aspect of the present invention, the actual torque of the engine is calculated from the combustion pressure in the cylinder of the diesel engine, and the fuel injection amount search is performed so that the actual torque is matched with the required torque determined by the engine operating conditions. Since the storage means (map) is rewritten, the required torque can always be obtained, and the effects of improving drivability, improving fuel efficiency, and reducing exhaust gas / black smoke can be obtained. Also,
Since it is a learning method, an effect of excellent responsiveness is also obtained.

According to the third aspect of the present invention, the required torque can be accurately grasped by calculating the required torque of the engine based on at least the accelerator depression amount. According to the fourth aspect of the invention, when the storage means (map) for searching the fuel injection amount is provided, the required torque of the engine is calculated based on the fuel injection amount searched from the storage means (map), whereby the required torque is calculated. It is possible to obtain the effect of being able to more accurately grasp

According to the fifth aspect of the present invention, the combustion pressure can be relatively easily and accurately detected by using the piezoelectric sensor provided at the position for receiving the combustion pressure acting on the glow plug as the combustion pressure detecting means. The effect is obtained. According to the sixth aspect of the invention, the combustion pressure can be detected relatively easily and accurately by using the piezoelectric sensor provided at the position for receiving the combustion pressure acting on the fuel injection nozzle as the combustion pressure detecting means. Is obtained.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention.

FIG. 2 is a system configuration diagram showing a first embodiment of the present invention.

FIG. 3 is a flowchart of a fuel injection amount control routine.

FIG. 4 is a flowchart of a fuel injection amount control routine showing a second embodiment.

FIG. 5: Flow chart of learning routine

[Explanation of symbols]

 1 Diesel engine 2 Fuel injection pump 3 DC motor for adjusting fuel injection amount 4 Fuel injection nozzle 5 Glow plug 6 Combustion pressure sensor (piezoelectric sensor) 6'Combustion pressure sensor (piezoelectric sensor) 7 Crank angle sensor 8 Accelerator sensor 9 Control unit

Claims (6)

[Claims] 1. A combustion pressure detecting means for detecting a combustion pressure in a cylinder of a diesel engine, an actual torque calculating means for calculating an actual torque of the engine based on the detected combustion pressure, and an engine based on an engine operating condition. And a fuel injection amount feedback control unit that feedback-controls the fuel injection amount by the fuel injection pump so that the actual torque matches the required torque. Engine fuel injection amount control device. 2. A fuel injection amount storage means for storing a fuel injection amount corresponding to an engine operating condition, and a fuel injection amount retrieving means for searching the fuel injection amount corresponding to an actual engine operating condition from the storage device. And a fuel injection amount signal output unit for outputting a signal corresponding to the fuel injection amount retrieved by the retrieval unit to control the fuel injection amount by the fuel injection pump. Combustion pressure detection means for detecting the combustion pressure in the cylinder, actual torque calculation means for calculating the actual torque of the engine based on the detected combustion pressure, and a request for calculating the required torque of the engine based on the engine operating conditions Engine operating conditions of the torque calculation means and the fuel injection amount storage means so that the actual torque matches the required torque. A fuel injection amount control device for a diesel engine, comprising: a stored value rewriting means for rewriting a stored value of another fuel injection amount. 3. The required torque calculation means calculates the required torque of the engine based on at least the accelerator depression amount.
A fuel injection amount control device for a diesel engine as described in the above. 4. The diesel engine according to claim 2, wherein the required torque calculation means calculates the required torque of the engine based on the fuel injection amount retrieved by the fuel injection amount retrieval means. Engine fuel injection amount control device. 5. The diesel engine according to claim 1, wherein the combustion pressure detecting means is a piezoelectric sensor provided at a position for receiving combustion pressure acting on a glow plug. Engine fuel injection amount control device. 6. The combustion sensor according to claim 1, wherein the combustion pressure detecting means is a piezoelectric sensor provided at a position for receiving combustion pressure acting on a fuel injection nozzle.
And a fuel injection amount control device for a diesel engine.