JP2002242733A - Fuel injection quantity control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection quantity control device for a diesel engine capable of accurately carrying out a fuel injection control for accurately reflecting a change of friction of a drive transmission system throughout a cold season. SOLUTION: A friction increment is calculated from a rotational speed and water temperature of the engine 2 by a friction increment calculating part 31. An injection quantity increment is calculated in an injection quantity increment calculating part 32 on the basis of the friction increment. A reduction coefficient is calculated in a reduction coefficient calculating part 33 on the basis of a time of traveling at a vehicle speed of a predetermined value or more calculated by a traveling time calculating part 34. The injection quantity increment calculated by the injection quantity increment calculating part 32 and the reduction coefficient calculated by the reduction coefficient calculating part 33 are multiplied by a multiplying part 35. In an injection quantity calculating part 37, a fuel injection quantity calculated on the basis of the rotational speed and a detection result of an accelerator sensor 24 is incrementally corrected on the basis of the multiplied value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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, in a fuel injection amount control device for a diesel engine, basically, a fuel injection amount is controlled based on an accelerator pedal opening and an engine rotation speed reflecting a driver's intention. Calculate the injection amount. However, it is desirable to optimize the fuel injection amount by performing a correction based on various factors with respect to the fuel injection amount thus calculated.

In order to optimize the fuel injection amount, it is desirable to consider friction generated in the engine and its drive transmission system. Especially when cold
Due to the fact that the clearance between the piston and the cylinder bore is smaller than when the engine is warm, the viscosity of the engine oil is large, and so on, the friction generated at each part of the engine is greater than when the engine is warm. Further, as the drive transmission system, for example, in an engine whose output shaft is connected to an automatic transmission, the engine output is transmitted due to an increase in the viscosity coefficient of the fluid in the torque converter when the engine is cold. The resistance (friction) at the time of cooling is also large at the time of cold. As described above, in a cold state in which the friction of the engine and its drive transmission system is large, it is desirable to optimize the fuel injection amount by increasing the fuel injection amount in comparison with the case of warm air.

Therefore, conventionally, regarding the fuel injection amount increase control, an increase correction value of the injection amount in the cold state is calculated from the temperature of the engine cooling water at the time of starting, and the increase correction value when the idle switch is turned off. There is proposed an apparatus for performing control to gradually reduce the pressure. According to such a control device, not only at the time of starting the engine, but also at the time of a wide cold state, it is possible to perform the increase correction of the fuel injection amount in consideration of the friction, and by performing the decrease control of the same increase correction value, It is also possible to perform fuel injection amount control in consideration of a decrease in friction after starting.

[0005]

In the above-described embodiment, when the increase control is performed based on the temperature of the cooling water including the time when the engine is not idling, it is not possible to accurately reflect the friction of the engine. However, when friction occurs in the drive transmission system, control that accurately reflects the friction is not always performed. This is due, for example, to the fact that the change in the friction of the fluid in the torque converter not only changes in accordance with the manner in which the cooling water temperature of the engine rises, but also changes in accordance with the manner in which the fluid is stirred by the engine output. I have.

When the injection amount increase correction value is controlled to be reduced when the idle switch is turned off in the above-described mode, the control mode of the injection amount is greatly affected by the driving mode of the driver. That is, for example, when the rotation speed is increased by depressing an accelerator pedal for warming up the engine, the idle amount is turned off and the injection amount is gradually reduced. In this case, since the friction of the drive transmission system such as the torque converter does not decrease so much at the time of the subsequent start, there is a possibility that a running failure due to insufficient torque may occur. Therefore,
Even in this case, eventually, the change in friction of the entire drive transmission system is not necessarily accurately reflected.

Conventionally, for example, Japanese Patent Application Laid-Open No. 2000-18
As disclosed in Japanese Patent Application Publication No. 058, when determining the injection amount at the time of starting from the rotation speed of the engine and the temperature of the engine cooling water, the fuel injection amount is increased and corrected based on the line pressure of the automatic transmission. Volume control devices are also known. According to this injection amount control device, at the time of startup, an increase in friction in an engine-driven oil pump for driving an automatic transmission is estimated based on the line pressure, thereby coping with the increase in friction. The fuel injection amount can be optimized.

However, since it is difficult to accurately monitor the friction of the entire drive system from the above line pressure, it is necessary to apply this device not only at the time of starting but also at the time of wide cold control. There is impossible. In addition, this technique is disadvantageous in terms of cost since it is necessary to provide a new sensor in order to accurately reflect the friction in the oil pump, even though the friction is required.

The present invention has been made in view of the above circumstances, and an object of the present invention is to perform more accurate fuel injection control that more accurately reflects a change in friction of a drive transmission system in a cold state. It is an object of the present invention to provide a diesel engine fuel injection amount control device which can be used.

[0010]

The means for achieving the above object and the effects thereof will be described below. The invention according to claim 1 is a fuel injection amount control device for a diesel engine that controls a fuel injection amount based on an accelerator opening, an engine rotation speed, and an environmental parameter, wherein the cooling water temperature of the engine is used as the environmental parameter. And a control unit for controlling the fuel injection amount using a running time of a vehicle equipped with the engine.

[0011] In the above configuration, as the parameters for controlling the fuel injection amount of the diesel engine, in addition to the accelerator opening and the engine rotation speed, the cooling water temperature of the engine and the running time of the vehicle equipped with the engine are used. Therefore, it is possible to accurately reflect the change in the friction of the engine at the time of cold based on the temperature of the cooling water of the engine. Moreover, according to the above configuration, since the fuel injection amount is controlled based on the running time, the fuel injection amount control can be performed by accurately reflecting the change in the friction of the drive transmission system in a wide cold state. become.

According to a first aspect of the present invention, as in the second aspect of the present invention, the control means determines the fuel injection amount which is basically determined in accordance with the accelerator opening and the engine speed. And an increase correction means for increasing and decreasing the fuel injection amount based on the travel time of the vehicle.

According to a first aspect of the present invention, as in the third aspect of the present invention, the control means adjusts the fuel injection amount basically determined according to the accelerator opening and the engine speed. An increase correction means for increasing the upper limit guard value provided for the engine based on the cooling water temperature of the engine; and a decrease correction means for decreasing the increase in the upper limit guard value based on the traveling time of the vehicle. You may make it comprise.

According to the third aspect of the invention, the upper limit guard value is corrected by the increase correction means and the decrease correction means. For this reason, when the driver indicates an intention to increase the torque, for example, by increasing the amount of depression of the accelerator pedal to compensate for the lack of torque due to the increase in friction, the intention display can be accurately reflected. Become.

According to a fourth aspect of the present invention, in the second or third aspect of the invention, the increase correction based on the cooling water temperature of the engine by the increase correction means is separately performed according to the rotation speed of the engine. Is the gist.

In the above configuration, the increase correction based on the engine cooling water temperature by the increase correction means is performed separately for each engine speed. For this reason, it becomes possible to correct the fuel injection amount to a more suitable amount according to the increase amount of the friction.

According to a second aspect of the present invention, in the vehicle according to the fifth aspect, the decrease correction means includes a drive transmission system connected to an output shaft of the engine. It is preferable that the increase-corrected fuel injection amount is corrected to decrease based on the friction reduction rate according to the traveling time of the vehicle.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the increase correction means and the decrease correction means require that the engine speed is lower than a predetermined speed. The gist is that the above correction is executed.

In the above configuration, when the rotational speed of the engine is equal to or less than a predetermined value, the correction by the increase correction means and the decrease correction means is performed. For this reason, when it is easy to feel the lack of torque in a cold state, such as when starting, the fuel injection amount is corrected, and deterioration in drivability due to the lack of torque can be avoided. .

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a fuel injection amount control device for a diesel engine according to the present invention will be described.
This will be described with reference to the drawings.

FIG. 1 shows a configuration of a fuel injection amount control device for a diesel engine according to the present embodiment. The diesel engine 1 shown in FIG. 1 includes a cylinder block 2, a cylinder head 4, and a piston 6. Further, an injector 10 is provided for directly injecting fuel into a combustion chamber 8 defined by the cylinder block 2, the cylinder head 4, and the piston 6.

The amount of fuel injected from the injector 10 is controlled by a fuel injection amount control mechanism 12. Any mechanism can be assumed as the fuel injection amount control mechanism 12. For example, when a common rail type is assumed, the fuel injection amount control mechanism 12 includes a common rail for storing fuel adjusted to a predetermined high pressure, and an electromagnetic valve provided between the common rail and the injector 10. And the like can be assumed. And
By controlling the opening and closing of the solenoid valve to control conduction and cutoff between the common rail and the injector 10, the amount of fuel injected from the injector 10 is controlled.

Further, this diesel engine is provided with an output shaft 14 for taking out the energy accompanying the explosion of the fuel injected from the injector 10 into the combustion chamber 8 as driving force. The output shaft 14 is configured to be connectable to a drive transmission system 16. The drive transmission system 16 finally drives the drive force of the output shaft 14 to drive wheels of a vehicle equipped with the diesel engine. Is transmitted.

The drive transmission system 16 includes, for example, a torque converter connected to the output shaft 14, an automatic transmission connected to the torque converter, a propeller shaft,
A configuration including a differential, an axle shaft, and the like can be assumed.

On the other hand, the fuel injection amount control device according to the present embodiment for controlling the fuel injection amount of the diesel engine 1 includes a sensor for detecting various states of the diesel engine 1 and the vehicle, and a detection result of the sensor. And an electronic control unit 30 for controlling the fuel injection amount control mechanism 12 based on the control signal.

The sensors include a water temperature sensor 20 for detecting the temperature of the cooling water of the diesel engine 1, a rotational speed sensor 22 for detecting the rotational speed of the engine 1, and the degree of depression of an accelerator pedal (not shown) by the driver. Sensor 24, a vehicle speed sensor 26, an ignition switch 28, and the like for detecting the vehicle speed.

Here, the manner of controlling the fuel injection amount by the fuel injection control device according to the present embodiment will be described in detail. Also in the present embodiment, the fuel amount injected through the injector 10 is basically equal to the rotational speed detected by the rotational speed sensor 22 and the accelerator opening detected by the accelerator sensor 24 during an operation other than idling. And is set based on FIG. 2 shows this fuel injection amount calculation procedure. This routine is repeatedly executed at predetermined time intervals.

That is, in step 100, when the fuel injection amount is calculated from various conditions such as the rotation speed and the accelerator opening, in step 110, it is determined whether the calculated fuel injection amount is larger than the upper limit guard value. Is determined. The upper limit guard value is set for each engine speed. When the calculated fuel injection amount is larger than the upper limit guard value, the upper limit guard value (step 120) is set as the fuel injection amount, and when the calculated fuel injection amount is smaller than the upper limit guard value. Is set to the fuel injection amount calculated as the fuel injection amount (step 130).

When the engine is cold, the amount of fuel injected is set to be increased based on the accelerator opening and the rotational speed in the above-described manner in consideration of the increase in friction between the diesel engine 1 and the drive transmission system 16. Control is performed. Specifically, the upper limit guard value is increased and corrected. As described above, by correcting only the upper limit guard value instead of correcting the fuel injection amount calculated in step 100 of FIG. 2, drivability can be suitably maintained. That is, by correcting the upper limit guard value, the driver can adjust the amount of depression of the accelerator pedal to avoid insufficient torque, so that a suitable driving feeling can be obtained.

The increase value of the upper guard value is determined based on the water temperature detected by the water temperature sensor 20 and the rotation speed detected by the rotation speed sensor 22. That is, since the friction between the engine 1 and the drive transmission system 16 increases as the engine is colder, the engine water temperature is used to determine the engine's water temperature. Also, the friction is
It depends not only on the engine water temperature but also on the rotation speed of the engine 1. Therefore, in the present embodiment, the amount of increase in the friction is calculated based on the engine water temperature and the rotational speed, and the amount of fuel required to offset the calculated amount of friction is calculated.

In order to calculate the amount of fuel required to offset the increase in friction according to the water temperature and rotation speed of the engine 1 in this embodiment, in the present embodiment, the relationship between the water temperature and rotation speed and the increase in friction is used. And a map that defines the relationship between the friction increase amount and the fuel amount for canceling the increase amount.

Here, a two-dimensional map that defines the relationship between the water temperature and rotation speed of the engine 1 and the friction increase amount is as follows:
The relationship between the engine water temperature and the amount of increase in friction as illustrated in FIG. 3 and the relationship between the rotational speed of the engine and the amount of increase in friction are prepared in advance by experiment.

On the other hand, the map for calculating the fuel amount for offsetting the increase in friction is based on the fact that the injection amount per 1 Nm of torque necessary to compensate for the torque loss due to the increase in friction is experimentally determined in advance for each engine speed. Prepared on request. By setting the required fuel amount for each engine rotation speed in this manner, it is possible to set an accurate fuel amount in consideration of the fact that the torque generated by a predetermined fuel injection amount changes depending on the operating state of the engine.

It is desirable that these series of experiments be performed on the assumption that the engine has just started cold. The fuel injection amount increase is calculated based on these maps. That is, based on the two-dimensional map that defines the relationship between the engine rotation speed and the water temperature and the friction increase amount, the friction increase amount base value Δ
F is calculated. Further, a required fuel amount q at the engine speed at that time is calculated from a map for calculating a fuel amount for canceling the friction increase amount. Then, the injection amount increase base value ΔQ is calculated as the product of the friction increase amount base value ΔF calculated from each of the maps and the required fuel amount q.

ΔQ = q × ΔF (c1) By the way, the injection amount increase base value ΔQ thus calculated
Basically reflects the water temperature of the engine 1. For this reason, as described above, this injection amount increase base value ΔQ may not accurately reflect the friction of the drive transmission system 16. That is, the friction increase amount base value ΔF obtained in the above mode is
Immediately after the start, even if the friction is appropriate as the entire friction of the engine 1 and the drive transmission system 16, the change in the friction of the drive transmission system 16 is greatly different depending on the driving state of the vehicle. There is a possibility that it is not something.

Therefore, in the present embodiment, the time during which the vehicle has traveled at a predetermined speed or more from the start is calculated, and the injection amount increase base value ΔQ is corrected to be reduced based on the calculated travel time. Specifically, as shown in FIG. 4 (a), the reduction mode of the friction of the engine and the drive transmission system at the time of a cold start (indicated as drive system friction in the figure) with respect to the running time is experimentally obtained in advance. And
From this reduction mode, the friction reduction rate with respect to the traveling time is calculated as a reduction coefficient in the mode shown in FIG.
This is prepared as a one-dimensional map.

The calculation of the reduction coefficient shown in FIG.
For example, it can be performed as follows. First, in FIG. 4A, the value A of the drive system friction immediately after starting
And the value C of the drive system friction at the time C at which the friction hardly changes even if the running time increases. Next, each time point x between the running time “0” and “C”
The value y of the drive system friction at is calculated. Thus, the decrease coefficient K at each time point x between the running time “0” and “C” is represented by the following equation.

K = (y−B) / (A−B) (c2) When the running time is longer than “C”, FIG.
As shown in (b), this reduction coefficient is set to “0”.

Based on the one-dimensional map of the traveling time and the reduction coefficient prepared in advance in this way, the final injection quantity increase value FQ in consideration of the drive system friction is obtained by the following equation. FQ = K × q × ΔF (c3) On the basis of the injection amount increase final value FQ calculated in this manner,
In the present embodiment, the upper limit guard value is changed. Specifically, the injection amount increase final value FQ calculated corresponding to the rotation speed is added to the upper limit guard value set for each rotation speed.

Hereinafter, the configuration of the electronic control unit 30 for performing the increase control of the injection amount in the above mode will be described. Figure 1
As shown in (1), the electronic control unit 30 takes in the detection results of the water temperature sensor 20 and the rotation speed sensor 22. Then, the friction increase calculating unit 31 calculates a friction increase base value ΔF based on the two-dimensional map based on the captured value.
The injection amount increase calculation section 32 calculates an injection amount increase base value ΔQ from the friction increase amount base value ΔF and the rotation speed.

On the other hand, in the running time calculating section 34, the vehicle speed sensor 26 is turned on after the ignition switch 28 is turned on.
The time during which the detected vehicle speed is equal to or higher than the predetermined value is calculated. This predetermined value is for determining a running state sufficient to contribute to a reduction in friction of the drive transmission system 16. When the time during which the vehicle has traveled at or above the predetermined vehicle speed is calculated in this manner, the reduction coefficient calculation unit 33 calculates the reduction coefficient K based on the calculated time.

In this way, the values calculated by the respective injection amount increase calculators 32 and the decrease coefficient calculator 33 are multiplied by the multiplier 35, whereby the injection amount increase final value FQ expressed by the above equation (c3) is obtained. Is calculated.

The injection amount increase final value FQ thus calculated
Is reflected in the amount of fuel injected from the injector 10 in a predetermined operating state of the engine. That is, in the present embodiment, when the engine rotation speed is equal to or more than the predetermined value α and equal to or less than the predetermined value β, the correction amount determination unit 36 reflects the same injection amount increase final value FQ in the injected fuel amount. Set as follows. Here, the predetermined value α is set to be smaller than the rotation speed during idling. on the other hand,
The predetermined value β is set to a rotational speed at which a torque loss due to an increase in friction during cold operation felt by the driver can be ignored.

As described above, by performing the above-described increase control of the injection amount only in the relatively low rotation speed region, the increase in the friction at the time of the cold state is insufficient for the torque, so that when the start is easy to be felt by the driver, it is accurately performed. Insufficient torque can be compensated. Then, in the rotation speed range smaller than the idling rotation speed, such as during deceleration, the increase in the fuel injection amount is not performed, so that the fuel consumption can be reduced. Also,
In the high rotation region, since the control for increasing the fuel injection amount is not performed, it is possible to avoid the occurrence of excessive torque due to the control for increasing the fuel amount.

As described above, based on the determination by the correction area determination unit 36, the injection amount calculation unit 37 basically performs the processing shown in FIG. 2 based on the engine speed and the accelerator opening. When the fuel injection amount increase control due to the friction increase amount is performed, the injection amount increase final value is compared with the upper limit guard value (solid line in FIG. 5) set for each engine rotation speed shown in FIG. FQ is added. As a result, the upper limit guard value is corrected to a value in a region indicated by oblique lines in FIG. Therefore, when the driver indicates the intention to increase the torque by depressing the accelerator pedal in response to the increase in the friction, the increase in the fuel amount can be controlled to reflect this intention, and the torque shortage can be reduced. It is possible to avoid traveling in a suitable manner.

The calculation of the injection amount increase final value FQ and the determination by the correction area determination unit 36 are also performed at predetermined time intervals in the present embodiment. According to the embodiment described above, the following effects can be obtained.

(1) An injection amount increase base value ΔQ corresponding to the friction of the engine 1 and the drive transmission system 16 at the time of cold start is obtained from the engine water temperature and the rotation speed.
The injection amount increase final value FQ was obtained by controlling the injection amount increase base value ΔQ to decrease according to the traveling time. As a result, even when the engine water temperature does not accurately reflect the friction of the drive transmission system 16, the injection amount increase final value FQ that accurately reflects the friction of the drive transmission system 16 can be obtained.

(2) By adding the injection amount increase final value FQ to the upper limit guard value, a suitable driving feeling can be obtained. (3) By providing the correction area determination unit 36, the increase correction of the upper limit guard value is not performed in an area where deterioration of drivability due to an increase in friction can be ignored. As a result, it is possible to avoid the occurrence of excessive torque due to the fuel amount increase control.

The above embodiment can be modified and implemented as follows. The calculation of the friction increase amount by the friction increase amount calculation unit 31 and the processing in the injection amount increase calculation unit 32
This may be performed in one step by preparing a two-dimensional map that defines the relationship between the engine water temperature and rotation speed and the injection amount increase. The manner of generating the two-dimensional map can be generated from the friction increase amount obtained as in the above embodiment and the injection amount necessary to offset the friction increase amount. However, the fuel injection amount required at each water temperature and rotation speed is obtained experimentally in advance to obtain
It is preferable to generate a dimensional map because the number of steps for generating the map can be reduced.

Further, the increase in the injection amount is not necessarily limited to the one obtained from the water temperature and the rotation speed, but may take into account the value of an appropriate parameter. Further, even if only the water temperature is used, the friction immediately after the cold start can be generally grasped.

Regarding the decrease coefficient, instead of setting the decrease coefficient based only on the traveling time, an appropriate parameter may be further added and set. The invention is not limited to the method in which the injection amount increase base value ΔQ is multiplied by a decrease coefficient based on the travel time. For example, the configuration may be such that the final injection amount increase final value FQ is calculated directly from a two-dimensional map of the traveling time and the water temperature or from a multidimensional map based on the values of some parameters in addition to the traveling time and the water temperature.

If the problem such as excessive torque can be neglected even when the fuel injection amount is increased in the high rotation speed region, the predetermined value β may not be provided. -Also in the rotation speed region smaller than the idle rotation speed, the control may be simplified by performing the injection amount increase control similar to the above embodiment and its modification.

The injection amount increase final value FQ is not limited to the addition thereof. For example, by appropriately setting the correction value, the fuel injection amount calculated in the previous step 100 may be multiplied. In step 100, the fuel injection amount including the running time and the engine water temperature may be calculated.

Instead of correcting the upper limit guard value, a configuration may be adopted in which both the fuel injection amount calculated in step 100 and the upper limit guard value are corrected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a diesel engine fuel injection amount control device, a diesel engine, and the like according to the present invention.

FIG. 2 is a flowchart for determining a fuel injection amount in the embodiment.

FIG. 3 is a diagram exemplifying a relationship between an engine water temperature and a friction increase amount.

FIG. 4 is a diagram showing a relationship between running time and friction.

FIG. 5 is a diagram illustrating a relationship between a rotation speed and an upper limit guard value.

[Explanation of symbols]

1. Diesel engine, 2. Cylinder block, 4.
Cylinder head, 6: piston, 8: combustion chamber, 10: injector, 12: fuel injection amount control mechanism, 14: output shaft, 16: drive transmission system.

Claims (6)

[Claims] A fuel injection amount control device for a diesel engine for controlling a fuel injection amount based on an accelerator opening, an engine rotation speed, and an environmental parameter, wherein the environmental parameter includes a cooling water temperature of the engine and the engine A fuel injection amount control device for a diesel engine, comprising: control means for controlling the fuel injection amount using a running time of a mounted vehicle. 2. An increase correction means for increasing an amount of fuel injection, which is basically determined according to the accelerator opening and the engine speed, based on a cooling water temperature of the engine. The fuel injection amount control device for a diesel engine according to claim 1, further comprising: a decrease correction unit configured to reduce and correct the determined fuel injection amount based on a running time of the vehicle. 3. The control means increases and corrects an upper limit guard value provided for a fuel injection amount basically obtained according to the accelerator opening and the engine rotation speed based on the cooling water temperature of the engine. 2. The fuel injection amount control device for a diesel engine according to claim 1, further comprising: an increase correction means; and a decrease correction means for decreasing the increase-corrected upper limit guard value based on the travel time of the vehicle. 4. The fuel injection amount control device for a diesel engine according to claim 2, wherein the increase correction based on the cooling water temperature of the engine by the increase correction means is performed separately in accordance with a rotation speed of the engine. 5. A decrease correction means for decreasing the increase in the fuel injection amount in a drive transmission system connected to an output shaft of the engine, based on a friction decrease rate according to a running time of the vehicle. The fuel injection amount control device for a diesel engine according to any one of claims 2 to 4, wherein 6. The apparatus according to claim 2, wherein said increase correction means and said decrease correction means execute said correction on condition that said engine rotation speed is lower than a predetermined rotation speed. Fuel injection amount control device for diesel engine.