JP2897426B2 - Engine fuel control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control device for an engine that controls the amount of fuel supplied to the engine according to intake pressure.

[Conventional technology]

Conventionally, as a fuel control device for an engine, for example,
As shown in JP 59-15656, an elderly injector is provided in the intake passage, and an intake pressure sensor for detecting intake pressure is provided in the intake passage downstream of the throttle valve,
There is known an apparatus in which the fuel injection amount from the injector is appropriately controlled in accordance with the intake pressure detected by the intake pressure sensor and the engine speed.

[Problems to be solved by the invention]

By the way, conventionally, there is an engine provided with an exhaust adjusting means for changing an exhaust flow state accompanied by a change in exhaust pressure according to an operating state of the engine, for example, an engine provided with a so-called sequential turbocharger. This includes a primary turbocharger and a secondary turbocharger provided in parallel with an exhaust passage of an engine, and an exhaust cut valve provided in an exhaust passage for guiding exhaust to the secondary turbocharger. In the flow rate region, the exhaust cut valve is closed and the exhaust gas is intensively supplied to the turbine of the primary turbocharger to obtain a high boost pressure, and in the high flow rate region, the exhaust cut valve is opened to reduce the exhaust gas. By appropriately supplying exhaust gas energy by dispersing and supplying the turbochargers to both turbochargers, an appropriate supercharging pressure is obtained (see JP-A-2-49925).

In such an engine, the exhaust pressure changes according to the opening and closing of the exhaust cut valve, and when the exhaust pressure changes, the filling amount differs even at the same intake pressure. Determining the amount alone causes a deviation in the air-fuel ratio.

Therefore, a plurality of maps for setting the correspondence between the intake pressure and the fuel supply amount are prepared, and the map used for calculating the fuel supply amount is switched according to the opening / closing of the exhaust cut valve (change of the exhaust gas flow state). It is conceivable to adjust the correspondence between the intake pressure and the fuel supply amount according to the pressure change. However, even in such a case, when the exhaust circulation state is changed, the exhaust adjusting means such as the exhaust cut valve has an operation delay, and
Since a certain period of time is required from the start of operation to the end of operation, simply switching the map at the same time as outputting the control signal for changing the exhaust gas flow state will result in matching the change in the exhaust pressure with the change in the fuel supply amount. The air-fuel ratio is shifted.

In view of such circumstances, the present invention can adjust the fuel supply amount calculated based on the intake pressure in accordance with the exhaust pressure that varies depending on the exhaust flow state, and particularly, even when the exhaust flow state is changed. Another object of the present invention is to provide a fuel supply device for an engine capable of appropriately adjusting a fuel supply amount and preventing a deviation of an air-fuel ratio.

[Means for solving the problem]

As shown in FIG. 1, a fuel supply device for supplying fuel to an engine En, an intake pressure detecting device b for detecting an intake pressure of the engine En, A fuel control means c for controlling a fuel supply amount from the fuel supply means a based on the intake pressure, and an exhaust gas for changing an exhaust flow state accompanied by a change in exhaust pressure according to an operating state of the engine. Adjusting means d;
A plurality of maps for setting the correspondence between the exhaust pressure and the fuel supply amount are provided, and a map used for calculating the fuel supply amount is selected from the maps, and the exhaust gas distribution state is changed by the exhaust adjustment means d. A switching means e for switching the map to be used after the state has been changed; and, during the map switching by the switching means e, during the period in which the exhaust pressure change occurs due to the operation of the exhaust adjustment means, the value after the switching is obtained from the value obtained by the map before the switching. Switching smoothing means f for gradually changing the fuel supply amount to a value determined by a map.

In this fuel control device, instead of the switching smoothing means f, the map switching by the switching means e is performed for a predetermined period of time from when the exhaust gas flow state is changed by the exhaust adjustment means d to when the exhaust pressure changes. Switching delay means g for delaying may be provided.

Alternatively, the switching smoothing means f and the switching delay means g may be used in combination, and after the delay by the switching delay means g, the switching smoothing means f may perform the smoothing process of the change in the fuel supply amount.

As the exhaust adjusting means g, for example, a primary turbocharger and a secondary turbocharger provided in parallel with an exhaust passage of the engine, and an exhaust passage for guiding exhaust to the secondary turbocharger, An exhaust cutoff valve that is opened and closed according to the operation of the exhaust cutoff valve to change the exhaust flow state, or the exhaust flow path of the exhaust silencer can be changed, and And a valve that changes the exhaust gas flow path by operation of the valve.

[Action]

According to the above configuration, the correspondence between the intake pressure and the fuel supply amount is adjusted by the selection and switching of the map by the switching unit so that the exhaust pressure differs between before and after the change in the exhaust gas flow state. Adjusted by the switching smoothing means or the switching delay means or both.
The fuel supply amount is appropriately adjusted so as to correspond to a change in the exhaust pressure in the process of changing the exhaust gas flow state.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

FIG. 2 schematically shows an engine provided with a fuel control device according to an embodiment of the present invention. This engine is provided with a sequential turbocharger as an exhaust gas adjusting means. In this figure, an engine En is, for example, a rotary piston engine, and its exhaust passage is divided into first and second two exhaust passages 1 and 2. Then, the turbine 3a of the primary turbocharger 3 is provided in the first exhaust passage 1,
Further, turbines 4a of the secondary turbocharger 4 are disposed in the second exhaust passage 2, respectively. The first and second exhaust passages 1 and 2 merge into one downstream of both turbines to form a combined exhaust passage 5.

The intake passage 6 is divided into a first intake passage 7 and a second intake passage 8 downstream of an air cleaner (not shown).
A compressor 3b of the primary turbocharger 3 is arranged in the middle of the first intake passage 7, and a compressor 4b of the secondary turbocharger 4 is arranged in the middle of the second intake passage 8. The first and second intake passages 7 and 8 are connected to the compressors 3b and 4b, respectively.
At the downstream of. An intercooler 9 and a throttle valve 10 are provided in the intake passage 6 downstream of the junction, and a negative pressure sensor (intake pressure detection means) 11 for detecting intake pressure downstream of the throttle valve is connected to the intercooler 9.
The downstream end of the intake passage 6 branches into two independent intake passages 12 and 13 corresponding to the respective cylinders of the engine En, and the independent intake passages 12 and 13 are respectively provided with fuel injectors 14 as fuel supply means. Are arranged. Intake passage 6
Air flow meter that detects the amount of intake air
15 are provided.

The first and second exhaust passages 1 and 2 are communicated with each other by a communication passage 20 on the upstream side of each turbine 3a. Also,
A second exhaust passage 2 that guides exhaust gas to the turbine 4 a of the secondary turbocharger 4 has a second exhaust passage 2 downstream of the communication passage 20.
An exhaust cut valve 21 that opens and closes the exhaust passage 2 to flow and shut off exhaust gas to the turbine 4a is provided. This exhaust cut valve 21 is a diaphragm type actuator.
It is opened and closed by 22. Further, a bypass passage 23 extending from the middle of the communication passage 22 and communicating with the combined exhaust passage 5 downstream of the turbines 3a and 4a is formed.
A wastegate valve 24 connected to a diaphragm type actuator 25 is provided. Furthermore, in order to pre-rotate the secondary turbocharger 4, the bypass passage 23
A leakage passage 26 is formed for communicating the upstream portion of the waste gate valve 24 with the downstream of the exhaust cut valve 21 of the second exhaust passage 2, and the passage 26 has a diaphragm type actuator.
An exhaust leak valve 27 connected to 28 is provided.

On the other hand, the second intake passage 8 is provided, downstream of the compressor 4b, with an intake cut valve 31 driven by a diaphragm type actuator 32 to open and close the passage 8. Further, the second intake passage 8 includes a compressor 4b
A relief passage 33 is formed so as to bypass the intake passage, and a diaphragm-type intake relief valve 34 is formed in the relief passage 33.
Is provided.

The drive system of each of the actuators and the like is as follows.

The actuator 22 of the exhaust cut valve 21 is connected to a three-way solenoid valve 42 through a passage 41, and the negative pressure or the atmospheric pressure from the vacuum tank 43 is selectively introduced into the actuator 22 by the three-way solenoid valve 42. Exhaust valve
21 is opened and closed. The three-way solenoid valve 42 is controlled by the control unit 50 in accordance with the operation state (for example, the intake air amount and the engine speed), so that, for example, as shown in FIG. In a region on the lower flow rate and lower rotation side (hereinafter, referred to as “P region”), the exhaust cut valve 21 is closed, and a region on a higher flow rate and higher rotation side (hereinafter “P +”) than the exhaust cut valve switching lines Ra and Rb.
In the “S region”, the exhaust cut valve 21 is opened. In the example shown in FIG. 3, P +
The exhaust cut valve switching lines Ra and Rb are provided with hysteresis when the shift to the S region is performed and when the shift is reversed.

Further, the actuator 28 of the exhaust leak valve 27 is connected to the first intake passage 7 downstream of the compressor 3b. Then, when the pressure downstream of the compressor 3b becomes equal to or higher than a predetermined value, the exhaust leak valve 27 is opened, so that when the exhaust cut valve 21 is closed, a small amount of exhaust gas flows through the exhaust leak passage 26 to the turbine 4a. And the secondary turbocharger 4 is pre-rotated. The actuator 25 of the wastegate valve 24 is connected to the compressor of the first intake passage 7 through the duty solenoid valve 44.
3b is communicated downstream, and the duty solenoid valve 44
Is controlled by the control unit 50 so that the exhaust bypass amount is controlled at the time of high supercharging or the like.

The actuator 32 of the intake cut valve 31 is a three-way solenoid valve 45
One input port of the three-way solenoid valve 45 is connected to the vacuum tank 43, and the other input port is connected to the atmospheric pressure in accordance with the pressure difference between the first intake passage 7 and the second intake passage 8. Is connected to a differential pressure detection valve 46 that switches between an open state and a closed state. When the three-way solenoid valve 45 is controlled by the control unit 50 in accordance with the operation state, the pressure in the second intake passage 8 increases after the exhaust cut valve 21 is opened during the transition from the P region to the P + S region. Accordingly, the intake cut valve 31 is opened. Further, the intake relief valve 34 is connected to a three-way solenoid valve 47, and the negative pressure or the atmospheric pressure is selectively guided by the three-way solenoid valve 47, so that the intake relief valve 34 is opened and closed. Then, by controlling the three-way solenoid valve 47 by the control unit 50 according to the operating state,
Immediately before the exhaust cut valve 21 is opened, the intake relief valve 34
Is to be closed.

The control unit 50 controls each actuator and the like as described above, and outputs an injection pulse signal to the injector 14 to control the fuel injection amount.The control unit 50 includes the negative pressure sensor 11 Also, a signal from the air flow meter 15, a signal from the engine speed sensor 51, and the like are input.

The memory in the control unit 50 includes a fuel map for the P region and a P + S as a fuel map for setting the fuel injection amount in accordance with the intake pressure and the engine speed.
Two types of maps for the area are stored. The control unit 50 performs control as shown in a flowchart described later according to a program, so that the functions as the fuel control means c, the switching means e, the switching smoothing means f, and the switching delay means g shown in FIG. It is configured to fulfill. In the present embodiment, when a change from the P region to the P + S region or from the P + S region to the P region (change of exhaust gas flow state) due to the opening / closing switching operation of the exhaust cut valve 21 is performed, the used fuel map corresponding to the change is changed. The switching is delayed for a predetermined time after the change is made, and after this delay, the fuel supply amount is gradually changed from the value obtained by the map before switching to the value obtained by the map after switching. ing.

An example of the fuel control by the control unit 50 will be described with reference to the flowchart of FIG. In addition,
This figure shows a routine for calculating the basic injection amount. In addition to this routine, a final injection amount is obtained from the basic injection amount and various correction amounts in a routine not shown, and the injection is executed using the final injection amount. Is done.

When the routine of FIG. 4 starts, first, in step S ₁
Then, check the operating state of the sequential turbocharger,
When only the primary turbocharger 3 is operating (P
State).

Step S ₁ when it is determined that the P state, depending on the engine speed and the intake pressure at that time, the value TEp obtained from the fuel map for P the basic injection amount TE (Step S _2). Then, in step S _3, determines whether the operating condition to be examined by the engine speed and the intake air amount is shifted to P + S region from the P region in FIG. 3, Step S ₁ when the judgment is NO Return to

When the determination of step S ₃ becomes YES (P from P region
+ Transition point to the S region) sets the predetermined time in the timer for switching delay (Step S _4), and then until the countdown to time-up timer, the basic injection quantity values TEp by fuel map for P TE (Step S
₅ ~S _7).

After time is up, from each of the fuel map and fuel map for P + S for P, reads the value TEp and TEp + s corresponding to the intake pressure and the engine speed (step S _8), compares the two values (step S _9). Then, [TEp <TEp +
s], the process of increasing the basic injection amount TE with TEp as the initial value by the smoothing amount x is repeated until [TE ≧ TEp + s] (steps S ₁₀ and S ₁₁ ). Also, [TEp <TEp +
If s], a process of reducing by an amount moderation basic injection amount TE that the initial value x of the TEp, repeated until [TE ≦ TEp + s] (step S _12, S _13). Thus performs the processing of the switching delay means by Step S ₄ to S _7, the processing of the I unit of switching by the subsequent step S ₈ to S _13, the smoothing process achieved (Step S ₁₁
Or when step S ₁₃ becomes YES), by switching the fuel maps to the value TEp + s obtained from the fuel map for P + S and the basic injection amount TE (step S _14). Then return.

On the other hand, not in the P state at step S ₁ (both turbochargers 3,
4 is operating in the P + S state), the P is determined according to the engine speed and the intake pressure at that time.
The value TEp + s obtained from the + S fuel map is used as the basic injection amount TE
And (step S _15). Then, in step S ₁₆ P +
It is determined whether or not the state has shifted from the S area to the P area. Then, after when the determination of step S ₁₆ becomes YES, and performing the step S ₄ processing as switching delay means and the switching of this means according to to S ₁₃ (steps S ₁₇ to S _26),
Change fuel map and find TE from fuel map for P
The the basic injection quantity TE p (step S _27). Then return.

The delay time and the smoothing amount x set in the timer are set so as to correspond to the operation delay and the operation speed of the exhaust cut valve 21 as described later. The value corresponding to the engine speed may be stored in a memory as a map and read from the map.

The operation of the apparatus of this embodiment will be described with reference to the time chart of FIG.

In the sequential turbocharger, in order to improve the supercharging efficiency, in the low flow rate region, the exhaust cut valve 21 is closed, and the exhaust gas is intensively sent only to the turbine 3a. In the high flow rate region, the exhaust cut valve 21 is opened to open the two turbines 3a and 4a.
The turbochargers 3, 4 are operated by sending exhaust gas to the turbocharger. With such a change, the exhaust pressure is different between the case where the exhaust cut valve 21 is closed and the case where the exhaust cut valve 21 is open, and its influence affects the intake pressure. Therefore, by properly using two types of fuel maps for P and P + S, the fuel injection amount in each case can be accurately obtained.

By the way, P + S
After shifting to the region, the supercharger drive signal is changed from P to P + S at the transition point t _0. That is, at this point t _0, the signal for changing the exhaust cut valve 21 from the closed to the open is output to the three-way solenoid valve 42. However, even after this signal is output, the opening operation of the exhaust cut valve 21 is started (at the time
A delay occurs before t ₁ ), and a certain period of time is required from the start of the opening operation of the exhaust cut valve 21 to the completion of the opening operation (time point t ₂ ). The change in exhaust pressure also corresponds to this. In contrast,
Exhaust cutoff valve operation start delay (t ₀ ~t ₁₎ is switched only fuel map is delayed (reference numeral 61), further corresponding to the exhaust cut valve operating speed of the exhaust cut valve operation time (t ₁ ~t ₂₎ An annealing process for switching the fuel map is performed (reference numeral 62). Therefore, the change in the basic injection amount is adjusted to correspond to the effect of the exhaust pressure fluctuation accompanying the operation of the exhaust cut valve 21, and the change from the P region to the P region
Even when shifting to the + S region (or from the P + S region to the P region), occurrence of a deviation in the air-fuel ratio is prevented.

In the above embodiment, both the switching delay means and the switching smoothing means are provided.
The transition of the air-fuel ratio during the transition is lower than in the past.

Further, as the exhaust gas adjusting means, a variable silencer device as shown in FIG. 6 may be used instead of or in combination with the above-described sequential turbocharger.

In this variable silencer device, the exhaust system is branched into two, and a main silencer 71, a sava silencer 72 and a catalytic converter 73 are arranged in each exhaust system as shown in FIG. These main silencers 71 are the first and second
The two outlet pipes 75 and 76 are provided. Main silencer 7
A resonance chamber, an expansion chamber (not shown) and the like are provided in the interior of the apparatus 1, and a short exhaust circulation path from the inlet pipe directly to the first outlet pipe 75 and a long exhaust path from the inlet pipe to the second outlet pipe 76 meandering. An exhaust circulation path is configured. Further, an opening / closing valve 77 is provided in each of the first outlet pipes 75 as a valve for changing the exhaust gas flow path. These open / close valves 77 are connected to actuators 78 via links or the like, and a three-way solenoid valve 79 for controlling the operating pressure of each actuator 78 is controlled by a control unit 80. In this manner, the opening and closing valve 77 is operated according to the operation state, and the exhaust sound path is changed, so that the exhaust sound is adjusted.

Also in the case of the variable silencer, the exhaust pressure changes due to the opening and closing of the open / close valve 77, and there is a delay in the operation of the open / close valve 77 itself, a delay until the exhaust pressure fluctuation reaches the combustion chamber, and the like.
Therefore, the fuel control may be performed according to the control according to the opening and closing of the exhaust cut valve of the sequential turbocharger.

〔The invention's effect〕

As described above, according to the device of the first aspect of the present invention, in a system for calculating and controlling the fuel supply amount from the map based on the intake pressure, a state in which the exhaust gas flow is changed by the exhaust adjustment means is set. By switching the map after that, the fuel supply amount calculated according to the intake pressure is adjusted so as to correspond to the change in the intake charge amount after the exhaust pressure change. By gradually reducing the fuel supply amount from the value obtained by the map to the value obtained by the switched map, it is possible to adjust to correspond to the transition of the exhaust pressure change at the time of changing the exhaust flow state, and to adjust the air-fuel ratio. The displacement can be suppressed.

According to the second aspect of the present invention, since the switching delay means for delaying the map switching is provided instead of the switching smoothing means, the switching is not performed until the exhaust pressure at the time of changing the exhaust gas flow state starts to change. The fuel supply amount can be adjusted using the previous map, and the deviation of the air-fuel ratio at the beginning of the change in the exhaust gas flow state can be suppressed.

According to the third aspect of the present invention, since the switching delay means and the switching smoothing means are used in combination, the fuel supply amount can be adjusted with higher accuracy.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the structure of the present invention, FIG. 2 is a schematic view of the entire apparatus according to an embodiment of the present invention, FIG. 3 is an explanatory view showing a control area of a sequential turbocharger, and FIG. FIG. 5 is a flow chart of the control, FIG. 5 is a time chart, and FIG. 6 is a schematic diagram showing another example of the exhaust adjustment means. a ... fuel supply means, b ... intake pressure detection means, c ...
Fuel control means, exhaust control means, switching means, f
... Switching smoothing means, g... Switching delay means, 1, 2... Exhaust passage, 3, 4... Turbocharger, 11.
……control unit.

Claims (5)

(57) [Claims] A fuel supply means for supplying fuel to the engine; an intake pressure detection means for detecting an intake pressure of the engine; and a fuel control means for controlling a fuel supply amount from the fuel supply means based on the intake pressure. And an exhaust adjusting means for changing an exhaust flow state with a change in exhaust pressure according to an operating state of the engine, and a plurality of maps for setting a correspondence relationship between the intake pressure and the fuel supply amount. Switching means for selecting a map to be used for calculating the fuel supply amount from among them, and switching the map to be used after the exhaust gas adjusting means changes the exhaust gas distribution state; During the period in which the exhaust pressure changes due to the operation of the exhaust adjusting means, the fuel is changed from the value obtained by the map before switching to the value obtained by the map after switching. An engine fuel control device comprising: switching smoothing means for gradually changing a supply amount. A fuel supply means for supplying fuel to the engine; an intake pressure detection means for detecting an intake pressure of the engine; and a fuel control means for controlling a fuel supply amount from the fuel supply means based on the intake pressure. And an exhaust adjusting means for changing an exhaust flow state with a change in exhaust pressure according to an operating state of the engine, and a plurality of maps for setting a correspondence relationship between the intake pressure and the fuel supply amount. Switching means for selecting a map to be used for calculating the fuel supply amount from among them, and switching the map to be used after the exhaust gas adjusting means changes the exhaust flow state; and Switching delay means for delaying a predetermined time from when the exhaust gas adjusting means changes the exhaust flow state to when the exhaust pressure changes. Engine fuel control. A fuel supply means for supplying fuel to the engine; an intake pressure detection means for detecting an intake pressure of the engine; and a fuel control means for controlling a fuel supply amount from the fuel supply means based on the intake pressure. And an exhaust adjusting means for changing an exhaust flow state with a change in exhaust pressure according to an operating state of the engine, and a plurality of maps for setting a correspondence relationship between the intake pressure and the fuel supply amount. Switching means for selecting a map to be used for calculating the fuel supply amount from among them, and switching the map to be used after the exhaust gas adjusting means changes the exhaust flow state; and Switching delay means for delaying a predetermined time from the time when the exhaust gas flow state is changed by the exhaust gas adjusting means to the time when the exhaust pressure changes; Fuel control apparatus for an engine is characterized in that a has a switching means for gradually changing the fuel supply amount to the value obtained by the map after switching from the value obtained by the map. 4. An exhaust control means is provided in a primary turbocharger and a secondary turbocharger provided in parallel with an exhaust passage of an engine, and in an exhaust passage leading exhaust to the secondary turbocharger. The engine fuel control device according to any one of claims 1 to 3, further comprising: an exhaust cut valve that is opened and closed according to a state, wherein an exhaust circulation state is changed by an operation of the exhaust cut valve. 5. The exhaust adjusting means is capable of changing an exhaust circulation path of an exhaust silencer, and
The engine fuel control device according to any one of claims 1 to 3, further comprising a valve that changes an exhaust flow path according to an operation state, wherein the exhaust flow state is changed by an operation of the valve.