JPH10252572A - Water injection amount control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a device to suppress a sudden change of a rack position of a water supply pump and a fuel injection pump, relating to a water injection amount control device suited for use in a water injection type Diesel engine. SOLUTION: This device has a water supply pump 40 changing a supply amount of water by changing a rack position, operating condition detection means 50 detecting an operating condition of an engine, and a control means 90 setting an injection amount of water based on detection information from the operating condition detection means. This constitution is formed such that when the operating condition of the engine is changed from a first operating condition to a second operating condition, in the case that a rack position change amount from a rack position in the first operating condition of the water supply pump 40 to a target rack position in the second operating condition is larger than a prescribed amount, by the control means 90, so as to decrease one time rack position change amount of the water supply pump 40 smaller than the prescribed amount, changing of the rack position of the water supply pump is divided into a plurality of times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water injection amount control device suitable for use in a water injection type diesel engine for injecting fuel and water into a combustion chamber.

[0002]

2. Description of the Related Art In a diesel engine, the combustion is performed by so-called in-cylinder air compression ignition, so that the generation mechanism of each component contained in the exhaust gas is different from that of gasoline premixed combustion. That is, in a diesel engine, combustion is generally performed in a state of excess air, and the emission concentration of HC (hydrocarbon) and CO (carbon monoxide) is relatively low, whereas the combustion temperature is high. Therefore, a relatively large amount of NOx (nitrogen oxide) is generated.

Further, after the fuel injection is performed, fuel vapor or an extremely over-concentrated air-fuel mixture is locally exposed to a high-temperature atmosphere, so that fuel molecules are thermally decomposed and carbon particles are easily formed. Therefore, the exhaust gas contains a large amount of soot. In particular, when the load is high, the combustion temperature becomes high, and N
Since the generation of Ox is promoted and the fuel density is higher than at the time of low load, the chance of the carbon particles coming into contact with air again decreases, and more soot is discharged.

Therefore, a so-called water-injection diesel engine has been proposed in which fuel and water are mixed and injected into a combustion chamber to perform combustion. In this water-injection diesel engine, water is injected into the combustion chamber together with fuel at the time of fuel injection, thereby reducing the combustion temperature and suppressing the generation of NOx. In addition, a small explosion due to vaporization of water, that is, a divergence phenomenon of water, generates a vortex in the combustion chamber, thereby improving the combustion efficiency and suppressing the generation of soot. Furthermore, fuel efficiency is improved by the improvement of the combustion efficiency.

[0005]

In such a water-injection diesel engine, the fuel injected into the combustion chamber depends on the operating state of the engine (specifically, the engine speed and the engine load). The amount of water is controlled. Further, the water injection type diesel engine is provided with two high pressure pumps: a fuel injection pump for pressurizing fuel and a water supply pump for pressurizing water. Among them, the fuel injection pump is configured similarly to the fuel injection pump provided in a normal diesel engine, and the fuel injection amount is changed by changing the rack position. In addition, the water supply pump is configured in substantially the same manner as such a fuel injection pump, and the water injection amount is controlled by changing the rack position.

For example, in FIG. 6, when the operating state of the engine changes from the state (first operating state) to the operating state (second operating state) (indicated by an arrow a in the figure).
Or when the operating state changes from the operating state (first operating state) to the operating state (second operating state) (indicated by arrow b in the figure)
In accordance with the time chart shown in FIG.
Control of fuel injection and water injection is performed.

[0007] That is, as shown in FIG. 7D, when it is detected that the operating state of the engine has changed from the state shown in FIG. The rack position Rww1 suitable for the first operation state is changed to the rack position Rww2 suitable for the second operation state (t = ta1). As a result, FIG.
As shown in (b), the water injection amount qw is changed to the rack position Rww2.
Increases to the injection amount qw2 corresponding to.

Next, as shown in FIG. 7C, after issuing a control signal to the water supply pump, the controller delays the control period τ (t = ta2) to increase the fuel injection amount. The rack position of the fuel injection pump is changed from the rack position Rwf1 suitable for the first operation state to the rack position Rwf2 suitable for the second operation state. Note that the reason why the rack position change signal to the fuel injection pump is delayed by the control period τ is that signals cannot be output at the same time simply because of the control of the controller. Will occur. Hereinafter, this control cycle is referred to as a control interval.

By the way, such a control interval τ
Is present, as shown in FIG. 7A, from ta1 to ta2
In the period up to, the fuel injection amount temporarily decreases. This is because until the rack position of the fuel injection pump is changed, that is, until t = ta2, the total injection amount of fuel and water is unchanged, so that the water injection amount increases during the period from ta1 to ta2. As a result, the fuel injection amount is reduced accordingly. Then, such a decrease in the fuel injection amount causes a problem that the output torque of the engine decreases and so-called breathing occurs.

[0010] Conversely, when it is detected that the operating state of the engine has changed from the state described above to the state described above, the rack position of the water supply pump is adapted by the controller to the second operating state. The rack position Rww2 is changed to the rack position Rww1 suitable for the first operation state (t = tb
1) As a result, as shown in FIG. 7B, the water injection amount is changed to the injection amount qw1 corresponding to the rack position Rww1 of the water supply pump.
Becomes

Then, after a control signal to the water supply pump is issued, the control signal is delayed by a control interval τ (t = tb
2) In order to reduce the fuel injection amount, the rack position of the fuel injection pump is changed from the rack position Rwf2 suitable for the second operation state to the rack position Rwf1 suitable for the first operation state.
In this case, contrary to the above, the fuel injection amount once increases during the period from tb1 to tb2. That is, when the rack position of the fuel injection pump is changed (t = tb2),
Since the total fuel and water injection amount is unchanged, t
During the period from b1 to tb2, the fuel injection amount increases by an amount corresponding to the decrease in the water injection amount. Then, there is a possibility that black smoke is discharged due to the excessive injection of the fuel.

The present invention has been made in view of the above problems, and suppresses abrupt fluctuations in the rack positions of a water supply pump and a fuel injection pump due to a change in the operation state of an engine, thereby reducing breathing caused by a decrease in torque. An object of the present invention is to provide a water injection amount control device capable of minimizing sticking and black smoke emission.

[0013]

According to a first aspect of the present invention, there is provided a water injection amount control device including a water supply pump for changing an amount of water supplied by changing a rack position. In a water-injection engine capable of injecting the water supplied by the water supply pump into a combustion chamber of the engine, operating state detecting means for detecting an operating state of the engine, based on detection information from the operating state detecting means, And control means for setting a water injection amount. When the operation state of the engine changes from the first operation state to the second operation state, the rack position of the water supply pump in the first operation state If the amount of change in the rack position from the second position to the target rack position in the second operating state is larger than a predetermined amount, the control means causes the single rack position change amount of the water supply pump to be larger than the predetermined amount. small Kunar so on, is characterized in that the change of the rack position of the water supply pump is configured to be divided into a plurality of times.

According to a second aspect of the present invention, there is provided a water injection amount control device according to the first aspect of the present invention, wherein the control means includes a control unit for controlling the water injection amount based on detection information from the operation state detection means.
Target rack position setting means for obtaining a target rack position of the water supply pump in the second operation state; and a rack position change amount from the rack position in the first operation state of the water supply pump to the target rack position. Means for calculating a rack position change amount to be calculated, and, when the rack position change amount is larger than a predetermined amount, setting one rack position change amount of the water supply pump to be smaller than the predetermined amount; Rack position change amount dividing means for dividing the change of the rack position of the supply pump into a plurality of times is provided.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the predetermined amount is set by a map of an engine speed and a load. It is characterized by: According to a fourth aspect of the present invention, in addition to the configuration of the second or third aspect, the water injection type engine changes a rack position in addition to the water supply pump. A fuel injection pump for changing the amount of fuel supplied by the control means, wherein the control means changes the rack position of the fuel injection pump when the change of the rack position of the water supply pump is divided into a plurality of times. And a fuel injection pump rack position change amount dividing means for dividing the fuel injection pump into a plurality of times like the water supply pump.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a water injection amount control device as one embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic block diagram focusing on the essential parts, FIG. 2 is a map showing the characteristics of the water injection amount, and FIG. 3 is a map for setting the rack position of the fuel injection pump.

In FIG. 1, reference numeral 1 denotes a fuel injection nozzle of a so-called water injection type diesel engine, which is mounted on a cylinder head (not shown) for each cylinder. The fuel injection nozzle 1 mixes and injects fuel and water into the combustion chamber. A water supply pump 40 is connected to the fuel injection nozzle 1 via a water pipe (water supply path) 30, and a fuel injection pump 70 is connected to the fuel injection nozzle 1 via a fuel pipe (fuel supply path) 31. I have.

Here, the water supply pump 40 and the fuel injection pump 70 have substantially the same configuration. That is, a rack actuator 81 is attached to the fuel injection pump 70 as shown in the figure, and the rack actuator 81 uses the rack (not shown) of the fuel injection pump 70.
Is moved, the amount of fuel supplied from the fuel injection pump 70 to the fuel injection nozzle 1 is changed.

A rack actuator 80 is mounted on the water supply pump 40. The rack actuator 80 moves a rack (not shown) of the water supply pump 40 so that the water injection pump 40 The amount of water supplied to 1 is changed. By changing the supply amounts of fuel and water from the pumps 40 and 70 to the fuel injection nozzle 1, the amounts of fuel and water actually injected from the fuel injection nozzle 1 are changed. ing.

By the way, each rack actuator 80,
81 is electrically connected to a controller (control means) 90 which will be described later, and according to a control signal from the controller 90, the water supply pump 40 and the fuel injection pump 70
Is controlled. And
Each of the pumps 40 and 70 can continuously change the discharge amount from 0 to the injection amount under the maximum engine load according to the rack position.

Next, the main parts of the present invention will be described.
As shown in FIG. 1, an engine speed sensor 91 for detecting the engine speed and an engine load sensor 92 for detecting the engine load are connected to the controller (control means) 90 described above. The engine load sensor 9
Reference numeral 2 is for detecting an engine load by detecting, for example, an amount of depression of an accelerator pedal. Further, the engine speed sensor 91 and the engine load sensor 92 have a function as operating state detecting means 50 for detecting an operating state of the engine.

In the controller 90, a water supply pump control unit 90A and a fuel injection pump control unit 90B are provided. These control units 90A and 90B control the operation of the rack actuators 80 and 81, respectively, based on the detection information from the operation state detection means 50, and control the rack positions of the pumps 40 and 70. The fluid (water,
(Fuel).

Specifically, in each of the control units 90A and 90B, the operating state detecting means 50 (the engine speed sensor 91
And whether the operating state of the engine has changed from a certain state (first operating state) to another state (second operating state) based on the detection information from the engine load sensor 92). When it is determined that the state has changed, an operation control signal is output to each of the rack actuators 80 and 81 so that the water injection amount and the fuel injection amount according to the engine operation state are obtained. Here, the state immediately before the engine operating state changes is referred to as a first operating state, and the state immediately after the engine operating state changes is referred to as a second operating state. Therefore, for example, when the operating state of the engine changes in the direction of arrow a shown in FIG.
The state corresponds to the first operating state, and the state corresponds to the second operating state. When the operating state of the engine changes in the direction of arrow b shown in FIG. 6, the state corresponds to the first operating state, and the state corresponds to the second operating state.

Now, such a water supply pump control unit 90
First, the water supply pump control unit 90A of the fuel injection pump control unit 90B will be described. The water supply pump control unit 90A includes a target rack position setting unit 60 and a rack position change amount as shown in FIG. A calculating unit 61 and a rack position change amount dividing unit 62 are provided. The target rack position setting means 60 calculates the target rack position Rww2 of the water supply pump 40 in the second operation state based on the detection information from the operation state detection means 50.

Here, the target rack position setting means 60 has a map (FIG. 2) for obtaining the target rack position Rww2.
Reference) is stored. In this map, the ratio of the optimal water injection amount to the fuel injection amount according to the engine speed and the engine load is stored. The target rack position setting means 60 calculates the engine speed and the engine load from this map. Based on this, the optimum target rack position Rww2 in the second operating state is set.

The rack position change amount calculating means 61
The target rack position Rww set by the target rack position setting means 60 from the rack position (ie, current rack position) Rww1 of the water supply pump 40 in the first operation state.
Rack position change amount ΔRww (= | Rww2−Rww1) up to 2
|) Is calculated. Further, the rack position change amount dividing means 62 includes a rack position change amount ΔRww calculated by the rack position change amount calculating means 61 and a predetermined amount ΔRwwmax.
When the rack position change amount ΔRww is larger than the predetermined amount ΔRwwmax, the water supply pump 40
The change in the rack position of the water supply pump 40 is divided into a plurality of times by setting the amount of change in the rack position at one time to be smaller than the predetermined amount ΔRwwmax.

Here, the predetermined amount ΔRwwmax is the maximum value of a single rack position change set by the engine speed and the engine load, and is a three-dimensional map (engine speed, engine speed, not shown). Load and ΔR
wwmax). Further, the predetermined amount ΔRwwmax is such that when the amount of one change of the rack position is equal to or more than the maximum value ΔRwwmax, the torque fluctuation of the engine becomes large, and the breathing of the engine and the discharge of black smoke may occur. This is the rack position change amount.

That is, in the present apparatus, when the rack position change amount ΔRww is larger than the predetermined amount ΔRwwmax, one rack position change amount of the water supply pump 40 is set to the predetermined amount ΔRwwma.
x so that the water supply pump 40
By dividing the change of the rack position into a plurality of times, the torque fluctuation when the engine operating state changes is suppressed as much as possible, and the breathing of the engine and the emission of black smoke are prevented.

Next, the fuel injection pump control unit 90B will be described.
Target rack position setting means 63 for setting a target rack position Rwf2 of the fuel injection pump 70 when the operating state of the engine changes from the first operating state to the second operating state;
Based on the information from the target rack position setting means 63 and the rack position change amount dividing means 62 provided in the water supply pump control unit 90A, the change of the rack position of the fuel injection pump 70 is divided into a plurality of times. A rack position change amount dividing means 64 is provided.

Here, the target rack position setting means 63
The rack change amount ΔRwf of the fuel injection pump 70 is set based on the rack position Rww of the water supply pump 40 set by the target rack position setting means 60 of the water supply pump 40. For example, a map as shown in FIG. Is stored. Further, the rack position change amount dividing means 64 is provided with a rack position change amount dividing means 62 of the water supply pump control unit 90A.
If the change in the rack position of the water supply pump 40 is divided into a plurality of times based on the information from the control unit, the change in the rack position of the fuel injection pump 70 is similarly divided into a plurality of times.

Accordingly, when the rack position change amount ΔRww of the water supply pump 40 is larger than the predetermined amount ΔRwwmax when the engine operation state changes, the fuel injection pump 7
The change of the rack position of 0 is also divided into the same number of times as the change number of the rack position of the water supply pump 40. Since the water injection amount control device as one embodiment of the present invention is configured as described above, when the operation state of the engine changes, the fuel injection and the fuel injection amount are controlled according to, for example, a time chart shown in FIG. Control of water injection is performed.

First, the case where the operating state of the engine changes from the state shown in FIG. 6 (first operating state) to the state (second operating state) will be described. The controller 90 determines whether the engine operating state has changed based on the engine speed information and the engine load information from the engine speed sensor 91 and the engine load sensor 92, and has determined that the engine operating state has changed. In this case, the target rack position setting unit 60 determines the target rack position Rww of the water supply pump 40 from a map as shown in FIG.
Set 2.

The rack position change amount ΔRww from the current rack position Rww1 of the water supply pump 40 to the target rack position Rww2 is calculated by the rack position change amount calculating means 61.
(= Rww2-Rww1) is calculated. Further, in the rack position change amount dividing means 62, the rack position change amount Δ
It is determined whether or not Rww is greater than a predetermined amount ΔRwwmax. Note that the predetermined amount ΔRwwmax is set based on an engine speed and an engine load from a map (not shown).

Here, when the rack position change amount ΔRww is larger than the predetermined amount ΔRwwmax, the rack position of the water supply pump is set so that the single rack position change amount of the water supply pump becomes smaller than the predetermined amount ΔRwwmax. Is split into multiple changes. In this case, specifically, the first indicated rack position Rwwd of the water supply pump 40 is set as Rww1 + ΔRwwmax.

Thus, as shown in the time chart of FIG. 4D, at the control start time t = ta1, the rack position of the water supply pump 40 is set to Rww1 + ΔRwwmax. As a result, the water injection amount qw becomes qw1 + Δqw, as shown in FIG. On the other hand, as shown in FIG. 4A, the fuel injection amount qf
Temporarily decreases. This is because until the rack position of the fuel injection pump 70 is changed (that is, until t = ta2), the total injection amount of fuel and water remains unchanged.
As a result, during the period from a1 to ta2, the fuel injection amount is reduced by the amount of the increased water injection amount.

However, in the present apparatus, one change in the rack position of the water supply pump 40 is suppressed so that the increment of the water injection amount is equal to or less than the predetermined amount ΔRwwmax. Thus, the reduction in torque can be suppressed to a minimum, and so-called breathing can be prevented. Then, in the next control cycle (t = ta2) of the controller 90, the rack position Rwf of the fuel injection pump 70 is controlled. At this time, the rack position Rwf of the fuel injection pump 70 is set by the target rack position setting means 63 of the fuel injection pump control unit 90B.
The rack position change amount dividing means 64 of the fuel injection pump control unit 90B fetches information from the rack position change amount dividing means 62 of the water supply pump control unit 90A, and changes the rack position of the water supply pump 40 a plurality of times. When divided, the change of the rack position of the fuel injection pump 70 is divided into a plurality of times, similarly to the division of the change of the rack position of the water supply pump 40.

That is, as shown in FIG.
At ta2, the rack position Rwf of the fuel injection pump 70
Is set to Rwf1 + ΔRwf. As a result, FIG.
As shown in (a), the fuel injection amount qf is qf1 + Δqf. Then, in the next control cycle (t = ta3) of the controller 90, the rack position Rww1 + ΔRwwmax of the water supply pump 40 is changed again.

At this time, the previous designated rack position Rwwd
(= Rww1 + ΔRwwmax) and the target rack position Rww2 [| Rww2− (Rww1 + ΔRwwmax) |] is a predetermined amount Δ
If it is larger than Rwwmax, the indicated rack position R
wwd is added to the previous rack position Rww1 + ΔRwwmax by a predetermined amount Δ
Rwwmax is the new designated rack position Rwwd
(T = ta3). Hereinafter, the change of the rack position of the water supply pump 40 is divided into a plurality of times until the difference between the rack position Rwwd changed immediately before and the target rack position Rww2 becomes smaller than the predetermined amount ΔRwwmax.

When the difference between the previous designated rack position Rwwd and the target rack position Rww2 becomes smaller than the predetermined amount ΔRwwmax, the target rack position Rww2 is set as the final designated rack position Rwwd. That is, Rww1 + n ·
The change of the rack position of the water supply pump 40 is repeated n times until ΔRwwmax> Rww2 is satisfied. FIG.
In the example shown in FIG. 7, the case where the second designated rack position Rwwd of the water supply pump 40 becomes the target rack position Rww2 is shown. That is, in this case, as shown in FIG. 4 (d), at t = ta3, the designated rack position Rwwd of the water supply pump 40 is set to the target rack position Rww2, thereby, as shown in FIG. 4 (b). As described above, the water injection amount qw changes stepwise from qw1 to qw2.

At this time, as shown in FIG. 4 (a), the fuel injection amount qf temporarily decreases as the water injection amount qw increases, as in the case of t = ta1. At the cycle (t = ta4), the rack position of the fuel injection pump 70 is set to Rwf2, whereby the water and fuel injection amounts correspond to the second operation state. On the other hand, when the operating state of the engine is as shown in FIG.
The operation state is changed from the operation state to the state (second operation state). In this case, the control is performed in substantially the same manner as described above. In the following cases, the small letter 2 indicates the first operating state, and the small letter 1 indicates the second operating state.

First, in the controller 90, the target rack position Rww1 of the water supply pump 40 is set in the target rack position setting means 60, and then the current water supply pump 40 of the water supply pump 40 is set by the rack position change amount calculation means 61. Rack position R
The rack position change amount ΔRww (= | Rww1−Rww2 |) from ww2 to the target rack position Rww1 is calculated. further,
In the rack position change amount dividing means 62, the rack position change amount ΔRww is determined by a predetermined amount ΔRww set based on the engine speed and the engine load from a map (not shown).
Determine if it is greater than max.

The rack position change amount ΔRww is equal to a predetermined amount ΔRwwma
When it is larger than x, the change of the rack position of the water supply pump is divided into a plurality of times so that the single rack position change amount of the water supply pump becomes smaller than the predetermined amount ΔRwwmax. In this case, specifically, the first water supply pump 40
Is set as Rww2−ΔRwwmax.

As a result, as shown in the time chart of FIG. 4D, at the control start time t = tb1, the rack position of the water supply pump 40 is set to Rww2−ΔRwwmax. As shown in FIG. 4B, qw2−Δqw. On the other hand, as shown in FIG. 4A, the fuel injection amount qf temporarily increases as the water injection amount decreases. This is until the rack position of the fuel injection pump 70 is changed (that is, until t = tB2).
Since the total injection amount of fuel and water does not change, the fuel injection amount increases as a result of the decrease in the water injection amount during the period from tB1 to tB2.

However, in the present apparatus, one change in the rack position of the water supply pump 40 is suppressed so that the decrease in the water injection amount is equal to or less than the predetermined amount ΔRwwmax. And the emission of black smoke can be minimized. Then, in the next control cycle (t = tb2) of the controller 90, the rack position Rwf of the fuel injection pump 70 is controlled. At this time,
The rack position Rwf of the fuel injection pump 70 is set by the target rack position setting means 63 of the fuel injection pump control unit 90B. If the change of the rack position of the water supply pump 40 is divided into a plurality of times by taking in the information from the rack position change amount dividing means 62 of the pump control unit 90A, the division of the rack position change of the water supply pump 40 is divided. Similarly to the control, the change of the rack position of the fuel injection pump 70 is divided into a plurality of times.

That is, as shown in FIG.
At tb2, the rack position Rwf of the fuel injection pump 70
Is set to Rwf2−ΔRwf. As a result, FIG.
As shown in (a), the fuel injection amount qf is qf2−Δqf. Then, in the next control cycle of the controller 90 (t = tb3), the rack position Rww2−ΔRwwmax of the water supply pump 40 is changed again.

At this time, the previous designated rack position Rwwd
(= Rww2−ΔRwwmax) and the target rack position Rww1 [| Rww1− (Rww2−ΔRwwmax) |] is a predetermined amount Δ
If it is larger than Rwwmax, the indicated rack position R
wwd is added to the previous rack position Rww2-ΔRwwmax by a predetermined amount Δ
Rwwmax is the new designated rack position Rwwd reduced by Rwwmax
(T = tb3). Hereinafter, until the difference between the rack position Rwwd changed immediately before and the target rack position Rww1 becomes smaller than the predetermined amount ΔRwwmax, the water supply pump 40
The rack position is divided into a plurality of times.

When the difference between the previous designated rack position Rwwd and the target rack position Rww1 is smaller than a predetermined amount ΔRwwmax, the target rack position Rww1 is set as the final designated rack position. That is, Rww2−n · ΔRww
The change of the rack position of the water supply pump 40 is repeated n times until max <Rww1 is satisfied. In the example shown in FIG. 4, the second indicated rack position R of the water supply pump 40 is set.
The case where wwd is the target rack position Rww1 is shown.
That is, in this case, as shown in FIG.
= Tb3, indicated rack position R of water supply pump 40
wwd is set to the target rack position Rww1, whereby
As shown in FIG. 4B, the water injection amount qw is gradually increased by qw2.
From qw1.

At this time, as shown in FIG. 4 (a), the fuel injection amount qf temporarily increases as the water injection amount qw decreases, as in the case of t = tb1, but the following control is performed. At the cycle (t = tb4), the rack position of the fuel injection pump 70 is set to Rwf1, whereby the water and fuel injection amounts are in accordance with the second operating state. By the way, such a water injection amount control device is provided with a water supply pump 40 according to a flowchart shown in FIG.
And rack position control of the fuel injection pump 70 is performed.

That is, first, in step S1, the target rack position Rww2 of the water supply pump 40 is read from the three-dimensional map as shown in FIG. 2 based on the engine speed and the engine load, and the flag F is set to 0. . Next, the process proceeds to step S2, where the maximum value ΔRwwmax of one rack position change is read from a three-dimensional map (not shown) based on the engine speed and the engine load.

Then, the process proceeds to step S3, in which the change amount | Rww2−Rww1 | from the current rack position Rww1 to the target rack position Rww2 and the maximum change amount of one rack position change of the water supply pump 40 obtained in step S2. Compare the magnitude with the value ΔRwwmax. Here, the change amount of the rack position | R
If ww2−Rww1 | is smaller than the above maximum value ΔRwwmax, the process proceeds to step S4, where the designated rack position Rwwd of the water supply pump 40 is set to the target rack position Rww2, and the flag F is set to 1. Next, step S
Proceed to 6.

On the other hand, if it is determined in step S3 that the amount of change | Rww2-Rww1 | of the rack position is larger than the maximum value ΔRwwmax, the process proceeds to step S5, where the designated rack position Rwwd is set to Rww1 + ΔRwwmax. Further, when step S5 is passed again in the subsequent routine, ΔRwwma is again determined with respect to the previous designated rack position Rwwd.
Rww1 = Rwwd is set so that x is added.

Then, in step S6, the water supply pump 40
Is driven to the designated rack position Rwwd, and water is injected at a predetermined water injection amount. Then, step S7
To the rack position increase ΔRwf of the fuel injection pump 70
Is set according to the injection amount of the water supply pump 40. At this time, the rack position increase Δ of the fuel injection pump 70 is
Rwf is set based on the rack position Rww of the water supply pump 40 controlled in step S6. Then, the process proceeds to step S8, where the rack position Rwf of the fuel injection pump 70 is set.
Is set to Rwf1 + ΔRwf, and the fuel injection control is executed.

Thereafter, in step S9, the flag is set to F
It is determined whether or not = 1, and if F = 1, the process returns. Otherwise, the process returns to step S3, and steps S3 to S8 are repeatedly executed until F = 1. In the water injection amount control device of the present invention, the water injection pump 40
In addition, since the rack position of the fuel injection pump 70 is controlled, there is an advantage that a rapid change in the rack position of the water supply pump 40 and the fuel injection pump 70 can be suppressed.
More specifically, when the engine operating state changes, the fuel injection amount temporarily drops sharply, and excessive fuel injection can be suppressed. Thus, there is an advantage that breathing due to a decrease in engine torque and emission of black smoke can be suppressed.

Further, according to the water injection amount control apparatus of the present apparatus, it is not necessary to provide any new parts and the like, and only the control logic needs to be changed, thus increasing the cost and weight. There is also an advantage that no increase is caused. Further, the predetermined amount ΔRwwmax is
Since it is set by the engine speed and the engine load, there is an advantage that fine rack position control can be performed according to the engine operating state.

[0055]

As described above in detail, according to the water injection amount control apparatus of the present invention, it is possible to suppress a rapid change in the rack position of the water supply pump, and thereby the engine When the operating state changes, there is an advantage that breathing due to a decrease in engine torque and emission of black smoke can be suppressed.

Further, according to the water injection amount control device of the present invention, in addition to the same advantages as described above, it is not necessary to provide new parts and the like in the conventional water injection engine. Since it is only necessary to change the control logic, there is an advantage that cost and weight do not increase.
Further, according to the water injection amount control device of the present invention described in claim 3, there is an advantage that fine rack position control can be performed according to the engine operating state.

Further, according to the water injection amount control device of the present invention, there is an advantage that a rapid change in the rack position of the water supply pump and the fuel injection pump can be suppressed. As a result, when the engine operating state changes,
The advantage is that the fuel injection amount can be prevented from temporarily dropping suddenly or fuel from being excessively injected, and it is possible to suppress breathing due to a decrease in engine torque and emission of black smoke. is there. Further, in comparison with the conventional water-injection engine, there is no need to provide new parts and the like, and only the control logic needs to be changed. Therefore, there is an advantage that cost and weight do not increase.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram focusing on a main configuration of a water injection amount control device as one embodiment of the present invention.

FIG. 2 is a map showing characteristics of a water injection amount in the water injection amount control device as one embodiment of the present invention.

FIG. 3 is a map for setting a rack position of a fuel injection pump in the water injection amount control device as one embodiment of the present invention.

FIG. 4 is a time chart for explaining an operation in the water injection amount control device as one embodiment of the present invention.

FIG. 5 is a flowchart for explaining an operation in the water injection amount control device as one embodiment of the present invention.

FIG. 6 is a diagram for explaining a change in an operating state of a general engine.

FIG. 7 is a time chart for explaining the operation of the conventional water injection amount control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection nozzle 1 30 Water pipe (water supply path) 31 Fuel pipe (fuel supply path) 40 Water supply pump 50 Operating state detecting means 60 Water supply pump target rack position setting means 61 Water supply pump rack position change amount calculating means 62 Water supply pump rack position change amount dividing means 63 Fuel injection pump target rack position setting means 64 Fuel injection pump rack position change amount division means 70 Fuel injection pump 80, 81 Rack actuator 90 Controller (control means) 90A Water supply pump control section 90B Fuel injection pump controller 91 Engine speed sensor 92 Engine load sensor

Claims (4)

[Claims] 1. A water injection engine having a water supply pump for changing an amount of water supplied by changing a rack position, and injecting the water supplied by the water supply pump into a combustion chamber of the engine. , An operating state detecting means for detecting an operating state of the engine, and a control means for setting the water injection amount based on the detection information from the operating state detecting means, wherein the operating state of the engine is the first. When the water supply pump changes from the operating state to the second operating state, the amount of change in the rack position from the rack position in the first operating state to the target rack position in the second operating state is greater than a predetermined amount. If the change is large, the control means divides the change of the rack position of the water supply pump into a plurality of times so that the amount of one rack position change of the water supply pump is smaller than the predetermined amount. Characterized in that it is configured to so that the water injection amount control device. 2. The method according to claim 1, wherein the control unit is configured to control the second state based on detection information from the operation state detection unit.
Target rack position setting means for obtaining a target rack position of the water supply pump in the operation state of the above, and a rack for calculating a rack position change amount from the rack position in the first operation state of the water supply pump to the target rack position. Position change amount calculating means; and if the rack position change amount is larger than a predetermined amount,
Rack position change amount dividing means for setting a single rack position change amount of the water supply pump to be smaller than the predetermined amount and dividing a change of the rack position of the water supply pump into a plurality of times. The water injection amount control device according to claim 1, characterized in that: 3. The water injection amount control device according to claim 1, wherein the predetermined amount is set by a map of an engine speed and a load. 4. The water injection engine further comprises a fuel injection pump for changing an amount of fuel supplied by changing a rack position, in addition to the water supply pump. When the change in the rack position of the pump is divided into a plurality of times, a fuel injection pump rack position change amount dividing means for dividing the change in the rack position of the fuel injection pump into a plurality of times like the water supply pump is provided. The water injection amount control device according to claim 2, wherein