JP3403428B2 - Method and apparatus for controlling fuel injection into a diesel internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to a method and apparatus for controlling fuel injection into a diesel internal combustion engine, and more particularly,
Solenoid valve is provided in association with each cylinder, the fuel metering is performed by the driving time, set when the driving time is reduced to below the predetermined first threshold value, the corresponding driving time zero The invention relates to a method and a device for controlling fuel injection into a diesel internal combustion engine in which at least one cylinder is deactivated.

[0002]

2. Description of the Related Art Such a method and apparatus is a DE-OS3
Known from 536207. This publication describes a fuel control device for a diesel internal combustion engine. This control device has a solenoid valve, and the fuel amount is determined by the driving time of the solenoid valve. Above a predetermined engine speed, the fuel supply to the individual combustion chambers of the internal combustion engine is interrupted at the same time when the required fuel is below a predetermined set value. In that case, the fuel supply to each predetermined combustion chamber is interrupted. In that case, in order to maintain the set engine output, the increased fuel amount is supplied to the other combustion chambers.

By simply stopping one cylinder,
The rotation of the internal combustion engine becomes quite uneven. Therefore, the interval between individual combustions, called the ignition angle, is of varying magnitude.
Furthermore, this method does not always provide a smooth transition when the cylinder is stopped or operating.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method and a device for controlling fuel injection into a diesel internal combustion engine in which it is guaranteed that stopping the cylinder will not hinder the running characteristics. It is to be.

[0005]

In order to solve the above problems, according to the present invention, an electromagnetic valve is provided in association with each cylinder, and fuel metering is performed by the driving time (T) thereof.
Is, the lower driving time than a predetermined first threshold (Tmin)
When reduced towards the corresponding driving time stop of the at least one cylinder is set to zero is performed, a method for controlling fuel injection into a diesel internal combustion engine, showing the relationship between the drive time and the torque Characteristic curve provided
And when the cylinder is stopped or released.
Driving time (TN) according to the characteristic curve
Set , the characteristic curve is cut at the set drive time.
Torque generated from a diesel internal combustion engine when replaced
The characteristics are such that the
Configurations of the adopted, also in the present invention, each silicon
Solenoid valve is provided in relation to the vehicle and its drive time (T)
Fuel metering is performed by the
When it decreases below the threshold value (Tmin),
Also set the drive time of one cylinder to zero
Internal combustion engine provided with means for stopping the engine
An apparatus for controlling fuel injection into the driving time and Torr
Memory and, cylindrical storing a characteristic curve showing the relationship between the click
When Da is stopped or released
Drive time (TN) according to the characteristic curve
And the characteristic curve is set to the set driving time.
Generated from a diesel internal combustion engine when switched
With the characteristic that the torque is maintained constant before and after switching
The adopted configuration is also adopted .

[0006]

In the preferred embodiment, after the drive time has been set to zero for at least one cylinder, the drive time of the remaining cylinders is increased so that the torque output from the diesel internal combustion engine remains constant. It

Also, in a preferred embodiment, at least 1
After the drive time of one cylinder is set to zero, the drive time of the remaining cylinders is increased so that the sum of the average effective pressures of the individual cylinders remains constant.

By increasing or decreasing the drive time of a cylinder that is not stopped according to a predetermined characteristic curve, the transition from a cylinder-free operation to a cylinder-stopped operation or vice versa is shock-free.

The cylinders are divided into two groups, and every other cylinder is made into one group in a predetermined ignition order, one group is stopped, and the other groups are operated, whereby the rotation of the internal combustion engine is extremely smooth. become.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1 schematically shows the structure of a control unit and a solenoid valve-controlled diesel injection pump. Each cylinder of an internal combustion engine (not shown) has a pump piston 1
Fuel is supplied via a fuel pump 10 having a fuel cell 5.
In that case, there can be only one fuel pump 10 per internal combustion engine, for example as in the case of a distribution pump. As a result, fuel is supplied alternately to the individual cylinders. On the other hand, a fuel pump may be provided for each cylinder. This type of pump is called a row pump or a pump nozzle unit.

The fuel pump is connected to the solenoid valve 20. A switching pulse is applied to the solenoid valve 20 from the electronic control unit 30 via the output stage 40. Solenoid valve 2
A signal is supplied to the electronic control unit 30 from a sensor 70 arranged at 0 and / or an injection nozzle (not shown).

The measuring device 50 detects the rotational movement of the pump camshaft 60 or the crankshaft and outputs a corresponding signal to the electronic control unit 30. Information about other quantities is provided to the electronic control unit 30 by other sensors 80.
Furthermore, the electronic control unit is connected to the memory element 90. The characteristic values shown in FIG. 3 are stored in this memory. The memory 90 can also be incorporated in the electronic control unit 30.

The electronic control unit 30 determines a desired feed start and feed period of the fuel pump 10 according to the amount detected by the sensor 80 and the movement of the pump cam shaft 60 detected by the measuring device 50. The driving point of the output stage 40 is calculated based on the target values of the feeding start and the feeding period. The solenoid valve 20 is in the first position where it starts to pump the pump at the desired starting point. The solenoid valve assumes a second position which again ends the delivery of the fuel pump at the desired end of delivery. As the quantity referred to in the calculation of the feed start and / or the feed period, one or more of the quantities such as the rotation speed (N), the lambda value and various temperature values are used. One of the sensors 80 produces a signal representative of the position of the accelerator pedal.

The pump cam shaft drives the pump piston 15, and the fuel of the fuel pump 10 is pressurized. In that case, the solenoid valve 20 controls the pressure build up. In that case, the solenoid valve 20 is preferably configured such that the pressure is formed when the solenoid valve 20 is closed. However, it is also possible for the pressure to build up when the solenoid valve 20 is opened.

The corresponding pressure in the fuel pump opens the injection valve (not shown), and the fuel reaches the combustion chamber of the internal combustion engine through the injection nozzle (not shown).

The electronic control unit 30 outputs a drive signal between a driving time point that determines the start of feeding and a driving time point that determines the end of feeding. The period between both drive points is called the drive time T.
The period between the actuation time and the time when the solenoid valve reaches its end position is called the switch-on time or the switch-off time of the solenoid valve.

When the valve needle reaches its end position, pressure build-up in the fuel pump begins. The solenoid valve returns to its original position only after a lapse of a predetermined delay time after the shutoff. Only after that, the pressure in the pump chamber is reduced to a predetermined value or less, the injection valve (not shown) is closed, and the fuel supply is completed.

Fuel is delivered to the combustion chamber of the internal combustion engine between the start of the delivery and the time when the pressure drops below a predetermined value and injection is no longer performed. The fuel injection amount is determined by this time interval. The drive time of the solenoid valve 20 is
The corresponding solenoid valves must be set to ensure that they reach their respective end positions. This means that the needle of the solenoid valve reaches the valve seat of the solenoid valve. As a result, the solenoid valve must be driven for the minimum drive time Tmin.

This minimum drive time Tmin must not be exceeded. As a result of this minimum drive time, the minimum fuel quantity QKmin is adjusted in accordance with the rotation of the internal combustion engine. If the rotation speed is high, this fuel amount becomes more than the so-called zero load amount. The zero load amount is the amount of fuel required to maintain the idle speed when the internal combustion engine is not loaded. When the load is small, the amount of fuel to be injected may exceed the required minimum fuel amount QKmin. Even in such an operating state, it is necessary to reduce the amount of fuel so that the fuel can be adjusted normally.

Therefore, when the load is small, the amount of fuel injected into the internal combustion engine is reduced by interrupting the fuel supply to the individual cylinders. However, this causes, among other things, the rotation of the individual cylinders when stopped or actuated to be non-smooth and the transition to be shocking. The operation with all cylinders and the operation with a reduced number of cylinders or vice versa must be carried out without impact without notice to the driver. Furthermore, smooth running of the internal combustion engine must be ensured.

According to the method of the present invention, the above need is met by the method of FIG. In a first step 200, the drive time T of the individual solenoid valve is calculated by the electronic control unit 30. In decision step 210, it is checked whether this drive time T is smaller than the minimum drive time Tmin.

If this is the case, then in step 215 the drive time of a group of cylinders is set to zero. In this regard, the individual cylinders are preferably divided into two groups. In that case, each group consists of the same number of cylinders. Each group is composed of every other cylinder in a predetermined ignition order. In step 215, the injection period is set to zero for these one group. Subsequently, in steps 220 and 225, the injection time TN of the other cylinder is calculated.

A simple method of this calculation is to double the driving time of other cylinders. However, this results in shocking transitions when stopping or activating one group of cylinders. This is because the combustion efficiency is usually non-uniform when the fuel amount is different. Normally, even if the injection amount is doubled, the output torque will not be doubled.

The relationship between the amount of fuel injected into a cylinder per stroke and the torque produced is shown in FIG. 3 in the form of the average pressure of the cylinder. Preferably, this relationship is stored in the memory 90 in the form of characteristic values (map) according to the rotation speed. In step 220, a value relating to the generated torque value is read from this characteristic value according to the driving time. It is also possible to use the injection amount instead of the driving time. The torque is stored in the map as a function F of the driving time per stroke or the injected fuel amount.

According to the invention, the same torque must be procured with half the number of cylinders after a group of cylinders is stopped, in order to make the transition when the group of cylinders is stopped shock-free. Therefore, each cylinder must generate twice the torque. Therefore step 2
At 25, the new drive time TN for the cylinder still operating is read from the map. In that case, the new drive time TN is set according to the inverse function F ′ of the original function F according to the doubled torque (2 * P).

Instead of using a map, step 220
It is also possible to calculate the torque on the basis of the driving time or the injected fuel amount in accordance with the predetermined function F. Accordingly, in step 225, the new drive time T is calculated according to the inverse function F ′ from twice the torque calculated in step 220.
N is calculated. The torque output from the internal combustion engine does not change after the cylinder group is stopped. The same applies to the sum of the mean effective pressures in the individual cylinders.

Next, at step 227, a predetermined value is stored in the auxiliary memory. In this embodiment, the value 1 indicates that the cylinder has been stopped.

If it is determined in the judgment step 210 that the driving time is longer than Tmin, the routine proceeds to step 230. It is checked here whether a cylinder stop has already taken place. In the negative, that is, when the value stored in the auxiliary memory H is not 1, the process proceeds to step 235.

On the other hand, if it is determined in the decision step 230 that the cylinder is stopped, that is, the value of the auxiliary memory is 1, the process proceeds to the decision unit 232, where the drive time T is It is checked whether it is above the upper threshold Tmax. The driving time T is a threshold value Tmax in the judgment unit 232.
If less than is detected, the cylinder stop is maintained. This means that the process of step 220 is performed as the next process. The second upper threshold value Tmax preferably has a value greater than the first lower threshold value Tmin.

At decision step 232, the drive time T
If it becomes clear that is greater than Tmax, then in step 237 one of the cylinder groups is released. At the same time, a value other than 1 is written in the auxiliary memory. The drive time is then reduced to make a shock-free transition.

Due to the second threshold value Tmax of the driving time, hysteresis occurs when the cylinder group is stopped and operated. The threshold Tmax is larger than the threshold Tmin. By doing so, it is possible to prevent vibrations around the threshold value Tmin during the driving time, and to prevent unstable switching between cylinder stop and driving by all cylinders.

At step 240, the value relating to the torque output according to the injection amount is read from the map. It is also possible to use the drive time T instead of the injection amount.
Torque is stored in the map as a function F of the amount of fuel injected per drive time or stroke.

In order to obtain a shock-free transition when operating the cylinder groups, the same torque must be provided by double the number of cylinders after the cylinder groups have been activated. Therefore, each cylinder need only supply half the torque. Therefore, in step 245, the new cylinder drive time TN is read from the map. In this case, the new drive time TN is read out according to the half torque P based on the inverse function F ′ of the original function F.

Alternatively, step 240 is performed according to the driving time or the injected fuel amount based on the predetermined function F.
You can also calculate the torque with. In that case, in step 245, a new drive time TN is calculated from the half of the torque calculated in step 240 according to the inverse function F ′.

In a particularly simple embodiment, step 2
The drive time T set at 00 is used. This means that the increased amount of fuel is set by steps 220, 225 and 227 while cylinder deactivation is desired. If the cylinder stop is released, the value set in step 200 is again used. This is indicated by a broken line in the figure.

After steps 227, 245 and 235, the fuel is metered in step 250 using the new drive time TN. If cylinder deactivation has taken place, this drive time is supplied to only half the cylinders.

FIG. 3 shows the relationship between the amount of fuel injected per stroke and the torque P generated from the cylinder corresponding to the cylinder. The torque corresponds to approximately the average effective pressure of the corresponding cylinder. The amount of fuel injected per stroke Q
K / Hub almost corresponds to the driving time T. This relationship is 3
It is shown by way of example for one rotational speed n1, n2 and n3. The rotation speed increases from n1 to n2 or n3. A nearly linear relationship is obtained between the two quantities, and the relationship is non-linear only when the fuel quantity is high. In that case, the torque P decreases below the value given in the linear relationship. Note that this reduction is
Larger when the rotation speed is large. As an example, two sets of values (torque, fuel amount injected per stroke) are described.

If, for example, the internal combustion engine is driven in an operating state in which 30 mg of fuel are metered into the cylinder per stroke, this corresponds to an average effective pressure of approximately 2 bar in the corresponding cylinder. If half of the cylinders are stopped in this operating state, the remaining cylinders must produce double the torque. This corresponds to an average effective pressure of about 4 bar. Corresponding to an average effective pressure of 4 bar is an injected fuel quantity of 45 mg per stroke.

Therefore, twice the amount of fuel is not required to provide a double average effective pressure. In this case, if a double fuel amount of 60 mg per stroke is injected, this amount causes a jump in torque at the time of stopping. The same applies to reactivating a stopped cylinder. In that case, the injection quantity cannot be easily halved and must be read out correspondingly from the map.

The characteristic curve shown in FIG. 3 is usually referred to as a Willan characteristic curve. It becomes particularly favorable when the characteristic curves are stored for different rotational speeds as shown. The fact that more than twice the torque is output when the injection quantity is doubled is based on the fact that the efficiency of the internal combustion engine becomes poor when the injected fuel quantity is small.

FIG. 4 shows characteristic values of the injection amount. The amount of fuel injected per stroke is illustrated according to the speed N. The zero load characteristic curve is shown by the dotted line with reference numeral 2. This characteristic curve corresponds to the fuel requirement in an unloaded internal combustion engine in order to keep it operating. If more fuel is injected, acceleration will result, and if the fuel quantity is less, the internal combustion engine will stop.

A solid line indicated by reference numeral 4 is a characteristic curve when the driving time has the minimum value. As is clear from the characteristic curve, the injected fuel amount falls below the zero load amount when the rotation speed is small, and rises above the zero load amount when the rotation speed increases.

When the rotational speed is high, the fuel is supplied more than the zero load amount. About 24 per minute
In the case of 00 revolutions, about twice the zero load amount is injected. The characteristic curve moves upward as the drive time T increases.

In order to reduce the injection quantity, half the cylinders are stopped by setting the driving time of the half cylinders to zero. Thereby, the torque procured by these cylinders will be provided by the remaining cylinders. To that end, these cylinders are supplied with increased fuel.

The characteristic curve that applies to the cylinders that are not stopped is shown at 3 when one cylinder group is stopped and the remaining cylinders are supplied with the corresponding increase. The characteristic curve 3 corresponds to the characteristic curve 1 in that case. In the case without cylinder stop shown in characteristic curve 1 and the case with cylinder stop shown in characteristic curve 3,
The torque generated by the internal combustion engine is equal. Characteristic curve 1 is valid when fuel is supplied to all cylinders, and characteristic curve 3 is valid for cylinders that are not stopped when there is a cylinder stop.

The reference numeral 4 is a characteristic curve similar to the characteristic curve 3 and corresponds to the case where the driving time reaches the second threshold value. This threshold becomes a switching threshold when switching from cylinder stop to full drive. This introduces hysteresis.

FIG. 5 shows the ignition sequence for various types of cylinder stops. Preferably the cylinders are divided into two groups. Cylinders 1, 3 and 2 belong to the first group, and cylinders 5, 6 and 4 belong to the second cylinder. The cylinders are preferably chosen such that metering and non-metering alternate with each other.

In FIG. 5, this is shown by way of example for a 6-cylinder internal combustion engine. In the left column, cylinder numbers, cylinder 1, cylinder 5, cylinder 3, cylinder 6, cylinder 2 and cylinder 4, each having a predetermined ignition sequence, are shown. On the right side, it is described which cylinder is sequentially supplied with fuel and is not supplied to that cylinder. X indicates fuel metering, and-indicates that metering is not performed.

Next, the difference between A, B and C in FIG. 5 will be described in detail. FIG. 5 (A) shows driving by the first cylinder group. Driving by the second cylinder group is shown in FIG. 5 (B). In that case, it is understood that the ignition angle, i.e. the distance between the two meterings, is of equal magnitude. This angle is 240
It becomes a crank angle of °. This drive is called group stop. Which cylinder is stopped when setting the cylinder stop is done according to a random selection. Due to the symmetrical ignition angle, the smoothness of rotation of the internal combustion engine is extremely high.

FIG. 5 (C) shows a so-called 8-cycle method, in which the first group and the second group alternate according to the combustion cycle. This method has the advantage that fuel is supplied to all cylinders at a uniform frequency. In the case of this type of metering, the cooling of the combustion chamber is not carried out, unlike in the case described above. There are three types of ignition angles (240 °, 120 ° and 360 °) here.
As a result, the rotation of the internal combustion engine becomes considerably uneven.

However, stopping the cylinder in this way is effective when the cylinder has an odd number. In the case of an odd number of cylinders, one group has more cylinders than the other group. In that case, the cylinders cannot be directly divided into the same number of groups. For this reason, metering is always performed on only every other cylinder in a given ignition sequence. In the case of an odd number of cylinders, rather than stopping a given group of cylinders, in the next combustion cycle fuel is metered to the cylinders that had not previously been fuel metered.

When this is applied to the method shown in FIG. 5, it is performed as follows in an odd number of cylinders. The cylinders are divided into two groups of different size. Here, too, each one group of cylinders is deactivated, in which case there is a shift between the two groups according to the entire engine cycle. This means, for example, in an internal combustion engine with five cylinders, the first group has two cylinders and the second group has three cylinders. First of all, two adjustments are performed in the first group, and then three adjustments are performed in the second group. This likewise results in a constant ignition angle. That is, the ignition angle is always the same. It should be noted that the ignition angle becomes twice as large as that before the stop when one cylinder group is stopped. Even if the number of cylinders is odd, metering and no metering alternate.

FIG. 6 shows the amount of drive time and the release of the stop, respectively, in the ignition sequence and when the cylinder is stopped. At time point A, the control unit determines that a cylinder stop is required. During the next metering, the drive time T is set to zero, which is indicated by-as in FIG. For the next metering, the drive time is increased according to the characteristic curve of Vilan, which is indicated by H. Next, the drive with the longer drive time and the drive (stop) set to zero are alternately performed.

This is maintained until at time B it is detected that fueling to all cylinders has been restarted.
From this point, fuel metering to the cylinder group that was stopped until then is started, and at the same time the drive time by the method described above is released.

[0056]

As is apparent from the above description, according to the present invention, when a part of cylinders is stopped or the cylinder is stopped.
When the stop is released, before switching the solenoid valve drive time
Since the torque afterwards is kept constant, it is
It is possible to improve driving characteristics remarkably without fluctuation
The effect is obtained .

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of a device of the present invention.

FIG. 2 is a flow chart for explaining the operation of the present invention.

FIG. 3 is a diagram showing characteristic values for calculating an increase amount when stopped and a decrease amount when reactivating a stopped cylinder.

FIG. 4 is a diagram showing a characteristic value of a fuel amount based on a rotation speed.

5 (A), (B), and (C) are diagrams showing ignition orders of various cylinders at the time of cylinder stop according to various cylinder stop principles.

FIG. 6 is a diagram of an ignition sequence showing the time points at which the cylinder is stopped and restarted.

[Explanation of symbols]

10 Fuel pump 15 pump piston 20 solenoid valve 30 control unit 40 output stages 50 Measuring device 60 cam shaft 80 sensor 90 memory

Front page continuation (51) Int.Cl. ⁷ Identification code FI F02D 43/00 F02D 43/00 301H 45/00 368 45/00 368S F02P 5/15 F02P 5/15 B (72) Inventor Thomas Henze German Federation Republic 7000 Stuttgart 1 Gustav Mahler Strasse 47 (72) Inventor Alfred Schmidt Federal Republic of Germany 7257 Ditzingen 4 Litterstraße 31 (56) Reference JP-A-56-2432 (JP, A) JP-A-59- 192841 (JP, A) JP 60-11656 (JP, A) JP 61-229957 (JP, A) JP 4-166634 (JP, A) JP 64-6332 (JP, B1) JP 54-17889 (JP, B1) German patent application publication 3536207 (DE, A 1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02D 17/02 F02D 41/40 F02D 43 / 00 301 F02P 5/15 F02D 45/00 368

Claims (11)

(57) [Claims] 1. A solenoid valve is provided in association with each cylinder, and fuel is metered according to its drive time (T), and the drive time is reduced below a predetermined first threshold value (Tmin). In a method for controlling fuel injection into a diesel internal combustion engine, wherein a corresponding drive time is set to zero and at least one cylinder is stopped , a characteristic curve showing a relationship between drive time and torque is provided. The cylinder is stopped or released.
Drive time (TN) is set according to the characteristic curve
And the characteristic curve is switched to the set drive time.
At this time, the torque generated from the diesel internal combustion engine switches
A method of controlling fuel injection into a diesel internal combustion engine, which is characterized by being maintained constant before and after the operation . 2. The drive time of the remaining cylinders is increased so that the torque generated from the diesel internal combustion engine is kept constant after the drive time is set to zero for at least one cylinder. The method according to claim 1, wherein 3. After the drive time of at least one cylinder is set to zero, the drive time of the remaining cylinders is increased so that the sum of the average effective pressures of the individual cylinders remains constant. The method of claim 1 characterized. 4. The characteristic curve is Villan.
n) The characteristic curve of claim 1 to 3 characterized in that
The method according to any one of 1. 5. The driving time, so that the ignition angle between each second injection equal, the method according to any one of claims 2 4, characterized in that it is set to zero. 6. Method according to claim 1, characterized in that metering and non-metering alternate. 7. The cylinder is divided into two groups,
7. A method according to any one of claims 1 to 6, characterized in that the different groups of cylinders are each consecutive in a predetermined firing order. If 8. cylinders is even, the driving time of one group are set to zero, the driving time of the other group is as defined in claim 7, characterized in that it is increased in accordance with the characteristic curve Method. 9. If the number of cylinders is odd, the drive times of one group or the other are alternately set to zero, in which case the alternation is carried out every engine cycle. Item 7. The method according to Item 7. 10. The driving time is a second threshold value (Tmax).
10. The method according to any one of claims 1 to 9, characterized in that the stop is released when the above is exceeded, in which case the second threshold value is greater than the first threshold value. 11. A solenoid valve is provided in association with each cylinder, and fuel is metered according to its driving time (T), and the driving time is reduced below a predetermined first threshold value (Tmin). In a device for controlling fuel injection to a diesel internal combustion engine, which is provided with means for stopping the cylinder by setting the drive time of at least one cylinder to zero, a characteristic curve showing the relationship between the drive time and the torque. To store
Memory and when the cylinder is stopped or released.
Drive time (TN) according to the characteristic curve
Means for switching the characteristic curve to a set drive time
At this time, the torque generated from the diesel internal combustion engine switches
A device for controlling fuel injection into a diesel internal combustion engine, which is characterized by being maintained constant before and after the operation .