JPH11125134A - Fuel injection control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device for an engine which can perform optimum fuel injection in accordance with properties of fuel. SOLUTION: This device is provided with a fuel injection nozzle 11 opening a valve by a fuel pressure to inject fuel in a combustion chamber, fuel injection pump 1 forcedly feeding fuel to the fuel injection nozzle 11, and a nozzle lift sensor 12 detecting an opening of the fuel injection nozzle 11. Based on a detection value of the nozzle lift sensor 12, properties of fuel including a viscosity characteristic of fuel is estimated, a control unit 18 is provided, which controls the operation of the fuel injection pump based on an estimation result of the properties of fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an engine fuel injection control device for maintaining fuel injection characteristics according to fuel properties.

[0002]

2. Description of the Related Art Conventionally, there has been an electronically controlled diesel engine in which the operation of a fuel injection pump is controlled by using a microcomputer so that a fuel injection amount and a fuel injection timing coincide with target values.

[0003] However, even in an electronically controlled diesel engine, if the viscosity characteristics of the fuel change depending on the type of fuel to be refueled, the fuel injection amount and the fuel injection timing deviate from the required values, and the engine will not operate. There is a possibility that the predetermined performance such as the output of the occurrence of the phenomenon cannot be obtained.

[0004] As a countermeasure, there is a conventional technique that estimates the viscosity characteristics of fuel based on the operating state of a fuel injection pump or the like, and controls the operation of the fuel injection pump by reflecting the viscosity characteristics of the fuel (Japanese Patent Application Laid-Open No. Hei 7-1995). 174040 publication).

Further, there is a type in which a pressure sensor for detecting the discharge pressure of the fuel injection pump is provided, and the operation of the fuel injection pump is controlled based on the detected value (Japanese Patent Laid-Open No. Hei 7-11951).
No. 6, JP-A-6-229304).

[0006]

However, when estimating the viscosity characteristics of the fuel based on the operating state of the fuel injection pump or the like, for example, an air conditioner switch or a power steering switch of the vehicle is provided to detect the load condition of the engine. Need to be performed, and the system becomes complicated.

Further, when a pressure sensor for detecting the discharge pressure of the fuel injection pump is provided, there is a problem that the operation for controlling the operation of the fuel injection pump is complicated.

The present invention has been made in view of the above problems, and has as its object to provide a fuel injection control device for an engine in which optimal fuel injection is performed in accordance with fuel properties.

[0009]

According to a first aspect of the present invention, there is provided a fuel injection control device for an engine, wherein a fuel injection nozzle for opening a valve by fuel pressure and injecting fuel into a combustion chamber, and forcing the fuel to the fuel injection nozzle. A fuel injection pump, a nozzle lift sensor for detecting an opening of the fuel injection nozzle, a means for estimating a fuel property including a viscosity characteristic of the fuel based on a detection value of the nozzle lift sensor, and a fuel based on an estimation result of the fuel property. Means for controlling the operation of the injection pump.

According to a second aspect of the present invention, there is provided a fuel injection control apparatus for an engine, wherein the fuel injection nozzle opens a valve by fuel pressure to inject fuel into a combustion chamber, a fuel injection pump for pumping fuel to the fuel injection nozzle, and an engine. Means for controlling the operation of the fuel injection pump in accordance with the operating conditions, a nozzle lift sensor for detecting the opening of the fuel injection nozzle, and means for calculating the fuel injection amount equivalent value S based on the detection value of the nozzle lift sensor. And a change rate α of a change amount | S ₁ -S ₂ | of the fuel injection amount equivalent value S with respect to a change amount | Q ₁ -Q ₂ | of the command value of the fuel injection amount.
Is calculated as α = | S ₁ −S ₂ | / | Q ₁ −Q ₂ |, and the calculated change rate α is compared with a predetermined value K ₁ to estimate the fuel properties including the viscosity characteristics of the fuel. Means and means for switching a map for controlling the operation of the fuel injection pump based on the estimation result of the fuel property.

According to a third aspect of the present invention, there is provided a fuel injection control device for an engine, the fuel injection nozzle opening a valve by fuel pressure and injecting fuel into a combustion chamber, a fuel injection pump for pumping fuel to the fuel injection nozzle, and an engine. Means for controlling the operation of the fuel injection pump in accordance with the operating conditions, a nozzle lift sensor for detecting the opening of the fuel injection nozzle, and means for calculating the fuel injection amount equivalent value S based on the detection value of the nozzle lift sensor. And a change rate α of a change amount | S ₁ -S ₂ | of the fuel injection amount equivalent value S with respect to a change amount | Q ₁ -Q ₂ | of the command value of the fuel injection amount.
Is calculated as α = | S ₁ −S ₂ | / | Q ₁ −Q ₂ |, and the calculated change rate α is compared with a predetermined value K ₂ to determine whether an abnormality of the fuel injection pump has occurred. Determination means.

According to a fourth aspect of the present invention, there is provided a fuel injection control apparatus for an engine, wherein the fuel injection nozzle opens a valve by fuel pressure and injects fuel into a combustion chamber, a fuel injection pump for pumping fuel to the fuel injection nozzle, and an engine. Means for controlling the operation of the fuel injection pump in accordance with the operating conditions, a nozzle lift sensor for detecting the opening of the fuel injection nozzle, and means for calculating the fuel injection amount equivalent value S based on the detection value of the nozzle lift sensor. And a change rate α of a change amount | S ₁ -S ₂ | of the fuel injection amount equivalent value S with respect to a change amount | Q ₁ -Q ₂ | of the command value of the fuel injection amount.
Is calculated as α = | S ₁ −S ₂ | / | Q ₁ −Q ₂ | and means for calculating a target value of the fuel injection amount or the fuel injection timing based on the calculated change rate α. It was taken.

According to a fifth aspect of the present invention, there is provided a fuel injection control device for an engine, the fuel injection nozzle opening a valve by fuel pressure and injecting fuel into a combustion chamber, a fuel injection pump for pumping fuel to the fuel injection nozzle, and an engine. Means for controlling the operation of the fuel injection pump in accordance with the operating conditions, a nozzle lift sensor for detecting the opening of the fuel injection nozzle, and means for calculating the fuel injection amount equivalent value S based on the detection value of the nozzle lift sensor. And a change rate α of a change amount | S ₁ -S ₂ | of the fuel injection amount equivalent value S with respect to a change amount | Q ₁ -Q ₂ | of the command value of the fuel injection amount.
Is calculated as α = | S ₁ −S ₂ | / | Q ₁ −Q ₂ |, and the fuel property including the viscosity characteristic of the fuel is calculated based on the calculated variation α ₂ −α ₁ of the change rate α. Means for estimating,
Means for switching a map for controlling the operation of the fuel injection pump based on the estimation result of the fuel property.

According to a sixth aspect of the present invention, in the fuel injection control device for an engine according to any one of the second to fifth aspects, the sampling of the fuel injection amount equivalent value S is performed within a predetermined time. did.

According to a seventh aspect of the present invention, in the fuel injection control device for an engine according to any one of the second to sixth aspects, the fuel injection amount equivalent value S is obtained by integrating the output voltage V of the nozzle lift sensor. Value.

According to an eighth aspect of the present invention, in the fuel injection control device for an engine according to the seventh aspect, the fuel injection amount equivalent value S is obtained by integrating a value at which the output voltage V of the nozzle lift sensor exceeds a predetermined value. Value.

According to a ninth aspect of the present invention, in the fuel injection control device for an engine according to any one of the second to sixth aspects, the output voltage V of the nozzle lift sensor is a predetermined value corresponding to the fuel injection amount equivalent value S. The time exceeded the value.

According to a tenth aspect of the present invention, in the fuel injection control device for an engine according to any one of the second to ninth aspects, the fuel injection amount equivalent value S is a value obtained by averaging a plurality of sampling values. To do.

According to an eleventh aspect of the present invention, in the fuel injection control device for an engine according to any one of the second to tenth aspects, the comparison condition of the change rate α is corrected according to the fuel temperature Tf. To do.

[0020]

In the fuel injection control device for an engine according to the first aspect of the present invention, the fuel property including the viscosity characteristic of the fuel is estimated based on the value detected by the nozzle lift sensor, and the fuel is estimated based on the fuel property estimation result. Controls the operation of the injection pump.

Thus, it is possible to prevent the fuel injection amount or the fuel injection timing from being shifted according to the properties of the fuel supplied to the fuel injection pump, and to maintain a predetermined performance such as engine output.

Further, even if the load of the engine changes due to the operation of the air conditioner or the power steering of the vehicle, the fuel property can be estimated. Therefore, the present invention can be implemented without increasing the number of components such as the power steering switch of the vehicle. The calculation for controlling the operation of the fuel injection pump can be simplified.

In the fuel injection control device for an engine according to the present invention, the fuel injection amount equivalent value S is calculated based on the detection value of the nozzle lift sensor, and the fuel injection amount equivalent value S with respect to the fuel injection amount command value Q is calculated. Change rate α of α = | S ₁ −S ₂
| / | Q ₁ -Q ₂ | is calculated.

Since the rate of change α changes in accordance with the amount of fuel leakage in the fuel injection pump, the rate of change α is compared with a predetermined value K ₁ to estimate the fuel properties including the viscosity characteristics of the fuel. The operation of the fuel injection pump is controlled by switching a map in which a target fuel injection amount, a target fuel injection timing, and the like are set based on the target map.

As a result, it is possible to prevent the fuel injection amount or the fuel injection timing from being shifted according to the type of fuel supplied to the fuel injection pump, and to maintain predetermined performance such as engine output.

In the fuel injection control device for an engine according to the third aspect, the fuel injection amount equivalent value S is calculated based on the detection value of the nozzle lift sensor, and the fuel injection amount equivalent value S with respect to the fuel injection amount command value Q is calculated. Change rate α of α = | S ₁ −S ₂
| / | Q ₁ -Q ₂ | is calculated.

Since the rate of change α changes in accordance with the amount of fuel leakage in the fuel injection pump, the rate of change α can be compared with a predetermined value K ₂ to accurately determine whether an abnormality has occurred in the fuel injection pump. Fail safe is measured.

In the fuel injection control device for an engine according to the fourth aspect, the fuel injection amount equivalent value S is calculated based on the detection value of the nozzle lift sensor, and the fuel injection amount equivalent value S with respect to the fuel injection amount command value Q is calculated. Change rate α of α = | S ₁ −S ₂
| / | Q ₁ -Q ₂ | is calculated.

The operation of the fuel injection pump is controlled by calculating the target value of the fuel injection amount or the fuel injection timing based on the change rate α.

As a result, the fuel injection amount and the fuel injection timing can be finely controlled according to the change in the fuel viscosity, and the predetermined performance such as the engine output can be maintained.

In the fuel injection control device for an engine according to the fifth aspect, the fuel injection amount equivalent value S is calculated based on the detection value of the nozzle lift sensor, and the fuel injection amount equivalent value S with respect to the fuel injection amount command value Q is calculated. Change rate α of α = | S ₁ −S ₂
| / | Q ₁ -Q ₂ | is calculated.

Since the rate of change α changes in accordance with the amount of fuel leakage in the fuel injection pump, the fuel properties including the viscosity characteristics of the fuel are estimated based on the amount of change α ₂ −α ₁ of the rate of change α, and this estimation is performed. The operation of the fuel injection pump is controlled by switching a map in which a target fuel injection amount or a target fuel injection timing is set based on the value.

Thus, it is possible to prevent the fuel injection amount or the fuel injection timing from shifting according to the type of fuel supplied to the fuel injection pump, and to maintain predetermined performance such as engine output.

In the engine fuel injection control device according to the sixth aspect, by sampling the fuel injection amount equivalent value S within a predetermined time, the accuracy of estimating the fuel property due to a change in the fuel temperature is deteriorated. Can be avoided.

In the fuel injection control device for an engine according to the present invention, the fuel property can be estimated with high accuracy by obtaining the fuel injection amount equivalent value S by integrating the output voltage V of the nozzle lift sensor.

In the fuel injection control device for an engine according to the present invention, the fuel injection amount equivalent value S is obtained by using a waveform of a high voltage portion where the output voltage V of the nozzle lift sensor greatly changes due to a change in fuel properties. Thereby, the accuracy of estimating the fuel property can be improved.

In the fuel injection control device for an engine according to the ninth aspect, the calculation is simplified by calculating the fuel injection amount equivalent value S as the time when the output voltage V of the nozzle lift sensor exceeds a predetermined value.

In the fuel injection control device for an engine according to the tenth aspect, the fuel injection amount equivalent value S is obtained by averaging a plurality of sampling values, thereby improving the accuracy of estimating the fuel property.

12. The fuel injection control device for an engine according to claim 11, wherein the comparison condition of the change rate α is a fuel temperature T.
By making corrections in accordance with f, it is possible to estimate the fuel properties and the like even under operating conditions in which the fuel temperature changes greatly, such as when the engine is cold or during warm-up.

[0040]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a fuel injection system for a diesel engine.

In FIG. 1, a feed pump 6 for pre-pressurizing fuel is mounted on an input shaft 6a of a fuel injection pump 1 which is driven to rotate in synchronization with the engine rotation, and is coaxially identical with the input shaft 6a. And a plunger 2 connected so as to reciprocate in the axial direction while being rotated.

The feed pump 6 sends out the pressurized fuel to the pump chamber 7, and excess fuel is returned to a fuel tank (not shown) to maintain the pressure in the pump chamber 7 constant.

A face cam 2a having cam lobes corresponding to the number of cylinders is provided coaxially on the plunger 2. The plunger 2 reciprocates in the axial direction each time the face cam 2a rides on the roller 8a. For example, in the case of a six-cylinder engine, when the input shaft 6a makes one rotation, the face cam 2a rides on the roller 8a six times during this time, and the plunger 2 reciprocates six times. Each time the plunger 2 reciprocates, it draws fuel into the plunger chamber 2b and pressurizes it. A return spring 2k pushes back the plunger 2 against the face cam 2a.

In the extension stroke of the plunger 2, fuel from the pump chamber 7 is sucked into the plunger chamber 2b through the fuel stop valve 10 and the slit 2j provided in the plunger 2.

On the other hand, since the pressurized fuel in the plunger high pressure chamber 2b is fed to the fuel injection nozzle 11 of each cylinder in the compression stroke of the plunger 2, it communicates with the plunger high pressure chamber 2b along the axis of the plunger 2. A communication passage 2c is formed, and a high-pressure passage 2d branches in the radial direction from the middle of the communication passage 2c. Further, a cutoff port 2e penetrating through the plunger 2 in the radial direction branches off from the distal end of the communication passage 2c.

Ports 2g of a number corresponding to the number of cylinders of the diesel engine are equally provided on the inner periphery of the cylinder 2f around the plunger 2 so as to be selectively connected to the high pressure passage 2d according to the rotational position of the plunger 2. , And a delivery valve 2h (only one is shown) is connected to each port 2g, and fuel is pressure-fed from the delivery valve 2h to the fuel injection nozzle 11.

The plunger 2 reciprocates six times each time it rotates, and pressurizes the inhaled fuel each time. The pressurized fuel is pushed into the high-pressure passage 2d from the communication passage 2c. The pressurized fuel is sent to the port 2g, and the fuel is fed to the fuel injection nozzle 11 via the corresponding delivery valve 2h.

On the other hand, a control sleeve 3 is slidably fitted on the outer periphery of the plunger 2 and normally covers the discharge passage 2e, and is closed. The passage 2e is released. As a result, the pressure in the plunger chamber 2b is released, and the pressure feed of the fuel from the delivery valve 2h to the fuel injection nozzle 11 ends.

The fuel injection nozzle 11 is a delivery valve 2h
The fuel (not shown) lifts a needle (not shown) to open the injection port, and directly injects fuel from the injection port to each cylinder.

Therefore, the amount of fuel fed into the fuel injection nozzle 11 varies depending on the position of the control sleeve 3. If the release passage 2e is released early when the plunger 2 moves in the compression direction, the fuel injection amount will be small. Conversely, when the release timing of the discharge passage 2e is delayed, the fuel injection amount increases.

In order to control the fuel injection amount, a rotary solenoid 4 for freely changing the position of the control sleeve 3 is provided. The rotary solenoid 4 is supplied with a fuel injection signal from a control unit 18 mainly composed of a microcomputer or the like, and changes the position of the control sleeve 3 according to the signal. The position of the control sleeve 3 is detected by the position sensor 5 and is fed back to the control unit 18.

Next, the position of the face cam 2a in the circumferential direction of the roller 8a on which the face cam 2a rides is controlled by the timer piston 8. In addition,
The illustrated timer piston 8 is rotated by 90 degrees from the actual position for convenience of explanation. A low-pressure chamber 8b and a high-pressure chamber 8c are provided on both sides of the timer piston 8, and the pressure in the high-pressure chamber 8c is adjusted by controlling the amount of a part of the high-pressure fuel released to the low-pressure chamber 8b by the control valve 9. Thus, the position of the timer piston 8 changes.

When the position of the timer piston 8 changes and the position of the roller 8a is advanced in the rotation direction of the face cam 2a,
The position at which the face cam 2a rides on the roller 8a is relatively delayed, and the timing of starting pressurization of the fuel by the plunger 2, that is, the fuel injection timing is delayed.
If the position of the roller 8a is delayed in the direction opposite to the rotation of the roller, the pressure start timing by the plunger 2 is advanced, and the fuel injection timing is advanced.

The operation of the control valve 9 is controlled in accordance with the operation state by the signal from the control unit 18, and the position of the timer piston 8 is adjusted.
The fuel injection timing is advanced and retarded.

The control unit 18 includes a nozzle lift sensor 12 for detecting the valve opening timing of the fuel injection nozzle 11, a fuel temperature sensor 15 for detecting the temperature of the fuel supplied to the fuel injection pump 1, and an engine cooling water temperature. From the cooling water temperature sensor 13 for detecting the engine speed, the accelerator opening sensor 16 for detecting the accelerator opening, the rotation speed sensor 14 for detecting the pump rotation speed, and the like, and based on these, the fuel injection amount described above. , And calculates and outputs a control signal for the injection timing.

The nozzle lift sensor 12 is mounted on the fuel injection nozzle 11 and is constituted by a piezoelectric element which is compressed with the lift of the needle, and outputs a signal corresponding to the lift of the needle.

The gist of the present invention is that the control unit 18 estimates the viscosity characteristics of the fuel based on the output of the nozzle lift sensor 12 and, based on the estimated value, adjusts the accelerator opening and the engine speed. The target position of the control sleeve 3 and the target position of the timer piston 8 are controlled by switching the map in which the target fuel injection amount and the target fuel injection timing are set. This prevents the actual fuel injection amount or fuel injection timing from changing in accordance with the viscosity characteristics of the fuel used.

A value obtained by integrating the output voltage V of the nozzle lift sensor 12 is calculated as a fuel injection amount equivalent value S, and the change rate α of the actual fuel injection amount equivalent value S with respect to the fuel injection amount command value Q is α = | S ₁ −S ₂ | / | Q ₁ −Q ₂ | is calculated. Estimate the viscosity characteristics of the fuel according to the change rate α, correct the target fuel injection amount and fuel injection timing according to the viscosity of the fuel,
The target position of the control sleeve 3 and the target position of the timer piston 8 are controlled, respectively.

FIG. 2 shows the waveform of the output voltage V of the nozzle lift sensor 12 when the type of fuel is changed under the same operating conditions. The output waveform indicated by the solid line in the figure indicates the output waveform when JIS standard No. 3 light oil is used, and the output waveform when the No. 2 light oil is used is indicated by the solid line. Thus, it can be seen that the output waveform of the nozzle lift sensor 12 of the special light oil 3 having a low fuel viscosity is smaller than that of the No. 2 light oil. That is, the fuel injection amount equivalent value S (the area of the output waveform) obtained by integrating the output voltage V of the nozzle lift sensor 12 becomes smaller due to the decrease in the fuel viscosity. This is the special diesel oil 2
Since the viscosity is lower than that of the light oil, the fuel injection nozzle 11 can be used in the compression stroke of the plunger 2 of the fuel injection pump 1.
This is because the amount of fuel that leaks to the pump chamber 7 without being sent to the pump chamber 7 increases.

FIG. 3 shows a characteristic in which the fuel injection amount equivalent value S changes with respect to the fuel injection amount command value Q. The characteristics shown by the solid line in the figure are the case where JIS standard No. 2 light oil is used, and the case where the special No. 3 light oil is used is shown by the broken line. Special No. 3 light oil with low fuel viscosity has a larger slope than No. 2 light oil. That is, the rate of change α of the fuel injection amount equivalent value S with respect to the command value Q increases as the fuel viscosity decreases. This is because, when the control sleeve 3 moves to increase the opening area of the discharge passage 2e, the amount of fuel released from the discharge passage 2e to the pump chamber 7 is larger in the special fuel oil 3 having a low fuel viscosity than in the light oil No. 2 when the control sleeve 3 moves. This is because the effect of the amount of fuel leaking into the pump chamber 7 through the gap around the plunger 2 is reduced.

Therefore, the viscosity characteristic of the fuel can be accurately estimated according to the change rate α of the actual fuel injection amount equivalent value S with respect to the fuel injection amount command value Q. By correcting the target position of the control sleeve 3 and the target position of the timer piston 8 in accordance with the fuel viscosity estimated in this way, the fuel injection amount and the fuel injection timing respectively approach the desired target values, and the generation of the engine is started. Predetermined performance such as output can be maintained.

In this embodiment, the fuel injection amount equivalent value S
Is a value obtained by integrating the output voltage V of the nozzle lift sensor 12, but a value obtained when the output voltage V of the nozzle lift sensor 12 exceeds a predetermined value may be integrated. By using the waveform of the high voltage portion where the output voltage V changes greatly due to the change in the fuel viscosity, the estimation accuracy of the fuel viscosity can be improved.

Further, it is also possible to calculate the time during which the output voltage V of the nozzle lift sensor 12 exceeds a predetermined value as the fuel injection amount equivalent value S, thereby simplifying the calculation.

A pressure sensor for detecting the fuel pressure guided from the delivery valve 2h to the fuel injection nozzle 11 may be provided instead of the nozzle lift sensor 12, and the viscosity characteristics of the fuel may be estimated based on the output of the pressure sensor.

The fuel injection amount equivalent value S can be obtained by averaging a plurality of sampling values to increase the accuracy of estimating the fuel viscosity.

The flow charts of FIGS. 4 to 6 show a series of routines for controlling the fuel injection amount and the fuel injection timing in accordance with the viscosity characteristics of the fuel.
Is executed at a constant cycle.

The routine shown in FIG. 4 will be described.
First, in step 1, it is determined whether a predetermined time (for example, several tens of seconds) has elapsed after the engine was started.

If this condition is satisfied, the routine proceeds to step 2, where the engine speed N is reduced to a predetermined low speed range N ₁ <N
<Determines whether or not there to N _2. N ₁ is, for example, an idle load rotation speed of 800 rpm, and N ₂ is 1200 rpm.
To

[0070] When this condition is satisfied, the process proceeds to Step 3 reads a command value to Q ₁ fuel injection amount. Then proceed to step 4 to determine whether the command value Q ₁ is in the range of _{Q L <Q 1 <Q H} .

[0071] When this condition is satisfied, the process proceeds to step 5, and calculates the actual fuel injection amount corresponding values S ₁ by integrating the output voltage V of the nozzle lift sensor 12.

[0072] Referring now the routine shown in FIG 5 will be described, first, at step 11, whether the routine operation time has elapsed since the calculated fuel injection amount corresponding values S ₁ at t is shorter than the predetermined value t ₀ Is determined. If the elapsed operation time t exceeds t ₀ , this routine ends because the fuel temperature may have changed significantly. Thus, it is possible to prevent the accuracy of estimating the fuel viscosity from being deteriorated due to the change in the fuel temperature.

If this condition is satisfied, step 12
It is determined whether the engine speed N is in a predetermined low speed range N ₃ <N <N ₄ . N ₃ is higher than N ₂ by 150
0 rpm and N ₃ is the maximum allowable engine speed.

If this condition is satisfied, step 13
Proceed to reads the command value Q ₂ of the fuel injection amount. Then the routine proceeds to step 14, determines whether the command value Q ₂ is in the range of _{Q L <Q 2 <Q H} .

If this condition is satisfied, step 15
To determine whether the difference | Q ₂ −Q ₁ | between the current Q ₂ and the previous Q ₁ is larger than a predetermined value ΔQ.

If this condition is satisfied, step 16
Willing to calculate the actual fuel injection quantity corresponding value S ₂ by integrating the output voltage V of the nozzle lift sensor 12.

Next, the routine shown in FIG. 6 will be described. First, in step 20, the change rate α of the fuel injection amount equivalent value S with respect to the command value Q is determined as follows: α = | S ₁ −S ₂ | / | Q ₁ −Q ₂ | Is calculated as

Then, the program proceeds to a step S 21, wherein predetermined values K ₁ and K _{2 serving} as comparison conditions for the change rate α are searched in accordance with the fuel temperature Tf based on preset tables. Tables not shown include predetermined values K ₁ and K ₂ corresponding to the fuel temperature Tf.
Is set in consideration of measurement errors and the like.

[0079] Then the process proceeds to step 22 and determines the calculated rate of change α is whether a predetermined value K ₁ is smaller than.

If it is determined that the change rate α is smaller than the predetermined value K ₁ , the process proceeds to step 23, where it is determined whether α is smaller than the predetermined value K ₂ . Here, if the α is determined that the predetermined value K ₂ is smaller than, judges that when the abnormal fuel injection pump 1 proceeds to step 26. K ₂ is K ₁ value less than can be determined that the amount of fuel leaking from a gap or the like around the plunger 2 into the pump chamber 7 is increased abnormally.

If it is determined that the change rate α is smaller than the predetermined value K ₁ and equal to or more than the predetermined value K _2, it is estimated that the special No. 3 light oil is used, and the routine proceeds to step 24, where the special no. The map is switched to the fuel injection amount map and the fuel injection timing map which are set in advance correspondingly, and this routine ends.

[0082] On the other hand, if the rate of change α is determined that the predetermined value K ₁ or more, and estimated that the No. 2 diesel oil is being used, the routine proceeds to step 25, which is set in advance corresponding to the No. 2 gas oil After switching to the fuel injection amount map and the fuel injection timing map, this routine ends.

The fuel injection amount map corresponding to the No. 2 light oil is set to increase the target fuel injection amount in anticipation of the amount of fuel leaking during the compression stroke of the plunger 2 as compared with the fuel injection amount map corresponding to the No. 3 light oil. Have been. For this reason, even if the fuel supplied to the tank changes from No. 2 light oil to special No. 3 light oil,
The fuel injection amount can be appropriately controlled, and predetermined performance such as engine output can be maintained.

By correcting the predetermined values K ₁ and K _{2 according} to the fuel temperature Tf, it is possible to estimate the fuel property even under an operating condition in which the fuel temperature changes greatly, such as during a cold period or during a warm-up period.

In another embodiment, the estimation of the fuel properties based on the change rate α is performed when the fuel temperature Tf is less than 50 ° <Tf.
The reaction may be performed under the condition of an equilibrium temperature range of <70 °. In this case, it is not necessary to correct the predetermined values K ₁ and K _{2 according} to the fuel temperature Tf.

In another embodiment, the control unit 18 corrects the target fuel injection amount and fuel injection timing based on the change rate α,
And the target position of the timer piston 8 may be controlled.

FIG. 7 is a flowchart showing a routine for controlling the fuel injection amount in accordance with the viscosity characteristics of the fuel.
It is executed in the control unit 18 at regular intervals.

To explain this, first, in step 3
In step 1, the change rate α of the fuel injection amount equivalent value S with respect to the command value Q is calculated as α = | S ₁ −S ₂ | / | Q ₁ −Q ₂ |.

Then, the process proceeds to a step 32, wherein a target fuel injection amount Q ′ set in advance based on the calculated change rate α is set.
And the target fuel injection timing IT ′ set in advance is corrected based on the change rate α, and the routine ends.

In this case, different types of fuel are mixed and supplied to the fuel injection pump 1 in the tank, or the fuel viscosity changes as the fuel temperature changes during operation of the engine. The fuel injection amount and the fuel injection timing can be finely controlled in response to the change, and predetermined performance such as engine output can be maintained.

In still another embodiment, the control unit 18 calculates the rate of change α each time a predetermined time elapses, estimates the viscosity characteristics of the fuel based on the amount of change in the rate of change α, and based on the estimated value. The target position of the control sleeve 3 and the target position of the timer piston 8 may be controlled by switching the map in which the target fuel injection amount and the target fuel injection timing according to the accelerator opening and the engine speed are set.

FIG. 8 is a flow chart showing a routine for controlling the fuel injection amount in accordance with the fuel viscosity characteristics.
It is executed in the control unit 18 at regular intervals.

This will be described first.
The change rate α ₁ of the fuel injection amount equivalent value S with respect to the command value Q at ₁
Is calculated as α ₁ = | S ₁ −S ₂ | / | Q ₁ −Q ₂ |.

Then, the process proceeds to a step 42, wherein it is determined whether or not a predetermined time has elapsed since the previous change rate α was calculated. If the predetermined time has elapsed, the routine proceeds to step 43, where the change rate α _{2 of the} fuel injection amount equivalent value S with respect to the command value Q is
Is calculated as α ₂ = | S ₁ −S ₂ | / | Q ₁ −Q ₂ |.

Then, the process proceeds to a step 44, wherein predetermined values θ and θ ′ serving as comparison conditions for the change rate α are searched for in accordance with the fuel temperature Tf based on preset tables. In each table (not shown), predetermined values θ and θ ′ corresponding to the fuel temperature Tf are set in consideration of measurement errors and the like.

[0096] Then the process proceeds to step 45, determines the difference between alpha _{2-.alpha. 1} of the two rates of change alpha ₂ and alpha ₁ is whether greater than the predetermined value theta.

If α ₂ −α ₁ is larger than the predetermined value θ, it is estimated that No. 2 light oil is used, and the routine proceeds to step 48, where a fuel injection amount map set in advance corresponding to No. 2 light oil is used. Then, the routine is ended after switching to the fuel injection timing map.

When α ₂ −α ₁ is equal to or smaller than the predetermined value θ, α ₂ −α ₁
Is smaller than a predetermined value θ ′.

If α ₂ −α ₁ is smaller than the predetermined value θ ′, it is estimated that the special No. 3 light oil is used, and step 47
Then, the map is switched to the fuel injection amount map and the fuel injection timing map that are set in advance corresponding to the special No. 3 light oil, and the present routine ends.

By correcting the predetermined values θ and θ ′ according to the fuel temperature Tf, it is possible to estimate the fuel properties even in an operating condition in which the fuel temperature changes greatly, such as during a cold period or during a warm-up period.

[Brief description of the drawings]

FIG. 1 is a system diagram of a fuel injection device showing an embodiment of the present invention.

FIG. 2 is an output waveform diagram of the nozzle lift sensor.

FIG. 3 is a characteristic diagram of a fuel injection amount equivalent value S with respect to a command value Q.

FIG. 4 is a flowchart for estimating a viscosity characteristic of a fuel.

FIG. 5 is a flowchart for estimating a viscosity characteristic of the fuel.

FIG. 6 is a flowchart for controlling a fuel injection amount according to the same fuel viscosity characteristic.

FIG. 7 is a flowchart for controlling a fuel injection amount according to a fuel viscosity characteristic according to another embodiment.

FIG. 8 is a flow chart for controlling a fuel injection amount according to a fuel viscosity characteristic according to still another embodiment.

[Explanation of symbols]

 Reference Signs List 1 fuel injection pump 2 plunger 3 control sleeve 4 rotary solenoid 8 timer piston 9 control valve 11 fuel injection nozzle 12 nozzle lift sensor 13 cooling water temperature sensor 14 speed sensor 15 fuel temperature sensor 16 accelerator opening sensor 18 control unit

Claims (11)

[Claims] 1. A fuel injection nozzle for opening a valve by fuel pressure to inject fuel into a combustion chamber, a fuel injection pump for pressure-feeding fuel to the fuel injection nozzle, a nozzle lift sensor for detecting an opening of the fuel injection nozzle, and A means for estimating a fuel property including a viscosity property of the fuel based on a detection value of the nozzle lift sensor; and a means for controlling operation of a fuel injection pump based on a result of estimating the fuel property. Engine fuel injection control device. 2. A fuel injection nozzle for opening fuel by a fuel pressure to inject fuel into a combustion chamber, a fuel injection pump for pumping fuel to the fuel injection nozzle, and an operation of the fuel injection pump according to operating conditions of the engine. Controlling means; a nozzle lift sensor for detecting the opening of the fuel injection nozzle; means for calculating a fuel injection amount equivalent value S based on a detection value of the nozzle lift sensor; and a change amount of a command value of the fuel injection amount | The change rate α of the change amount | S ₁ −S ₂ | of the fuel injection amount equivalent value S with respect to Q ₁ −Q ₂ |
Means for calculating as | S ₁ -S ₂ | / | Q ₁ -Q ₂ | and means for estimating fuel properties including the viscosity characteristics of the fuel by comparing the calculated change rate α with a predetermined value K _1. Means for switching a map for controlling the operation of the fuel injection pump based on the estimation result of the fuel property; and a fuel injection control device for an engine. 3. A fuel injection nozzle for opening fuel by a fuel pressure to inject fuel into a combustion chamber, a fuel injection pump for pumping fuel to the fuel injection nozzle, and an operation of the fuel injection pump in accordance with operating conditions of the engine. Controlling means; a nozzle lift sensor for detecting the opening of the fuel injection nozzle; means for calculating a fuel injection amount equivalent value S based on a detection value of the nozzle lift sensor; and a change amount of a command value of the fuel injection amount | A change rate α of the change amount | S ₁ −S ₂ | of the fuel injection amount equivalent value S with respect to Q ₁ −Q ₂ |
Means for calculating as | S ₁ -S ₂ | / | Q ₁ -Q ₂ |, and means for comparing the calculated change rate α with a predetermined value K ₂ to determine whether an abnormality has occurred in the fuel injection pump. A fuel injection control device for an engine, comprising: 4. A fuel injection nozzle for opening a valve by fuel pressure to inject fuel into a combustion chamber, a fuel injection pump for pumping fuel to the fuel injection nozzle, and an operation of the fuel injection pump according to operating conditions of the engine. Controlling means; a nozzle lift sensor for detecting the opening of the fuel injection nozzle; means for calculating a fuel injection amount equivalent value S based on a detection value of the nozzle lift sensor; and a change amount of a command value of the fuel injection amount | A change rate α of the change amount | S ₁ −S ₂ | of the fuel injection amount equivalent value S with respect to Q ₁ −Q ₂ |
Means for calculating | S ₁ -S ₂ | / | Q ₁ -Q ₂ |, and means for calculating a target value of the fuel injection amount or the fuel injection timing based on the calculated change rate α. A fuel injection control device for an engine, comprising: 5. A fuel injection nozzle for opening a valve by fuel pressure to inject fuel into a combustion chamber, a fuel injection pump for pumping fuel to the fuel injection nozzle, and an operation of the fuel injection pump according to operating conditions of the engine. Controlling means; a nozzle lift sensor for detecting the opening of the fuel injection nozzle; means for calculating a fuel injection amount equivalent value S based on a detection value of the nozzle lift sensor; and a change amount of a command value of the fuel injection amount | A change rate α of the change amount | S ₁ −S ₂ | of the fuel injection amount equivalent value S with respect to Q ₁ −Q ₂ |
Means for calculating as | S ₁ -S ₂ | / | Q ₁ -Q ₂ | and means for estimating fuel properties including the viscosity characteristics of the fuel based on the calculated variation α ₂ -α ₁ of the rate of change α Means for switching a map for controlling the operation of the fuel injection pump based on the estimation result of the fuel property; and means for controlling the fuel injection of the engine. 6. The fuel injection control device for an engine according to claim 2, wherein the sampling of the fuel injection amount equivalent value S is performed within a predetermined time. 7. The fuel injection control device for an engine according to claim 2, wherein the fuel injection amount equivalent value S is a value obtained by integrating an output voltage V of a nozzle lift sensor. . 8. The fuel injection control device for an engine according to claim 7, wherein the fuel injection amount equivalent value S is a value obtained by integrating a value exceeding a predetermined value of an output voltage V of the nozzle lift sensor. . 9. The fuel injection for an engine according to claim 2, wherein the value S corresponding to the fuel injection amount is a time during which the output voltage V of the nozzle lift sensor exceeds a predetermined value. Control device. 10. The fuel injection amount equivalent value S is a value obtained by averaging a plurality of sampling values.
10. The fuel injection control device for an engine according to any one of claims 1 to 9. 11. A condition for comparing the change rate α with a fuel temperature Tf
The fuel injection control device for an engine according to any one of claims 2 to 10, wherein the correction is performed according to the following.