JPS61126335A - Fuel supply quantity control unit of engine with supercharger - Google Patents

Abstract

PURPOSE:To certainly defect a trouble in a supercharger so that fuel cutting can be well achieved, by providing both an over-supercharge detecting means for detecting any over-supercharge and a delay means for reserving an assigned period of time until the fuel quantity is reduced to zero. CONSTITUTION:An over-supercharge detecting means is provided with a number of detecting levels equal to the number of superchargers so as to detect the presence of any over-supercharge. When presence of any over-supercharge is detected, a fuel supply quantity detecting means reduces the fuel quantity to zero. A delay means reserves a delay of an assigned period of time from the time of detecting the presence of an over-supercharge until the fuel quantity is reduced to zero. Said assigned period of time is set per each detecting level of the over-supercharge detecting means and made longer as the detecting level is lower. Any trouble in a supercharger can be certainly detected in this way so that fuel cutting can be well achieved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel supply amount control device for an engine equipped with a plurality of superchargers, and in particular, when excessive supercharging is performed, the fuel supply amount is reduced. The present invention relates to a device that reliably performs so-called fuel cut, which reduces the fuel consumption to zero.

[Conventional technology]

In a supercharged engine, if a failure occurs in which the wastegate pulp does not open, resulting in excessive supercharging, the engine will be adversely affected. For this reason, conventional methods have been used to detect this failure and stop the engine by stopping the fuel supply to the engine, a so-called fuel cut.
It is done to protect the engine. For example, Japanese Patent Application Laid-Open No. 57-200638 discloses a technology that cuts fuel when Q/N (Q: intake air amount, N: engine rotation speed) becomes larger than a predetermined value. has been done. Here, Q/N is used as a value representing the degree of supercharging.

[Problem that the invention seeks to solve]

However, for an engine having a plurality of superchargers, the above-mentioned conventional technology has a problem in that it is not possible to appropriately cut fuel when the waste gate valve fails to open.

For example, in an engine with two superchargers, if the wastegate valve of one supercharger does not open,
The amount of increase in supercharging pressure will be lower than if both superchargers were affected. Furthermore, the characteristics of the diaphragm that controls the opening and closing of the wastegate valve are temperature dependent, and the responsiveness of opening and closing the valve to changes in boost pressure is worse at low temperatures than at high temperatures.

For this reason, if the detection level for detecting excessive supercharging is set to a supercharging pressure value that is reached when the waste gate valves of both superchargers no longer open, the waste gate valve of one supercharger will When only the gate valve fails to open, the boost pressure does not reach the set value, so the failure cannot be detected, and the engine is adversely affected before it is detected.

In addition, if the detection level is set to a boost pressure value that reaches an early stage when the waste gate valve of one turbocharger stops opening, both turbochargers will fail even if one turbocharger fails. However, if the throttle valve is suddenly opened at low temperatures and the wastegate valve response is poor, the boost pressure will temporarily increase, which may incorrectly be detected as a turbocharger failure. Sometimes I put it away.

Therefore, in an engine equipped with a plurality of superchargers, the present invention reliably detects the occurrence of a failure regardless of the number of turbochargers in which the failure has occurred, cuts fuel, and responds to the waste gate valve. The purpose of the present invention is to prevent a temporary increase in supercharging pressure caused by poor performance from being mistakenly detected as a fault in the supercharger, and thereby preventing a fuel cut.

[Means for solving problems]

Therefore, in the present invention, even if the supercharging pressure does not become too high, if the duration is long, the fuel is cut as a failure of the supercharger, and if the supercharging pressure is high enough, the duration is Even if the period is short, it is characterized by a fuel cut as a failure of the supercharger.

Specifically, the fuel supply amount control device for a supercharged engine according to the present invention, as shown in FIG. It is equipped with an amount detection means.

The over-supercharging detection means has the same number of detection levels as the superchargers, and detects that supercharging is excessively performed exceeding each detection level. Further, the fuel supply amount detection means controls the amount of fuel supplied from the fuel supply device to the engine according to the operating state of the engine, and the overcharging detection means detects that excessive supercharging is being performed. Then, the fuel amount is set to zero. Furthermore, the delay means has a predetermined time delay from when the overcharging detection means detects that excessive supercharging is being performed until the fuel supply amount control means sets the fuel amount to zero. The predetermined time period is set for each detection level in the overcharging detection means, and is made longer as the detection level is lower.

[Effect]

If the supercharger is not malfunctioning and is functioning normally, a predetermined amount of fuel is supplied from the fuel supply device to the engine according to the operating state of the engine.

Also, at that time, even if the temperature around the engine is low and the response of the waste gate valve is poor, and the boost pressure temporarily increases when the throttle valve is suddenly opened, the boost pressure will be lower than the Since the amount of time exceeding the detection level, which is set to a relatively low level, is short, the amount of fuel supplied will not be set to zero, and fuel will be supplied normally as in the case described above.

On the other hand, if a failure occurs in which the waste gate valve of one of the multiple turbochargers does not open, the boost pressure will exceed the lowest detection level set according to the throttle valve opening. This state is not temporary and continues beyond a relatively long delay time corresponding to the detection level (therefore, the amount of fuel to be supplied is set to zero and a fuel cut is performed).

Furthermore, if a failure occurs in which the wastegate pulps of two or more turbochargers do not open, the boost pressure will exceed a relatively high detection level in response to the opening of the throttle valve. After a relatively short delay time corresponding to this, the amount of supplied fuel is reduced to zero, and a fuel cut is performed.

〔Example〕

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

FIG. 2 is a system configuration diagram of an embodiment of the present invention,
This example is a fuel-injected engine with two superchargers.

Here, 18 is the engine body, and 4.6 is the supercharger. The intake passage 20 of the engine body 18 is divided into two systems on the air intake side from the throttle valve 92, compressors 76 and 80 of each supercharger 4.6 are inserted in each system, and the exhaust passage 22 is also the same as the intake passage 20.
It is divided into systems, and turbines 74 and 78 of each supercharger 4.6 are inserted in each system. In addition, a bypass passage 82.84 is further formed in parallel with the passage in which the turbine 74.78 is inserted.
．． A wastegate valve 8.10 is provided in each case 84. Each wastegate valve 8.10 is controlled to open and close by an actuator 14.16. That is, the valve body 86.88 of each wastegate valve 8.10 is connected to each actuator 14.
16 is linked to a built-in diaphragm (not shown), while the diaphragm is adapted to deform under the pressure of the intake passage 20. As a result, while the pressure in the intake passage 20 is lower in absolute pressure than the predetermined pressure, each wastegate valve 8.10 is closed, but when the pressure in the intake passage 20 becomes higher than the above pressure, each wastegate valve 8.10 is closed. The valve 8.10 is opened to prevent the pressure in the intake passage 20, that is, the boost pressure, from becoming too high.

As mentioned above, since the engine in this case is a fuel injection type, the intake manifold 90 forming a part of the intake passage 20 is provided with the fuel injection valve 12. , the opening and closing are controlled in response to electrical drive pulses sent from the control circuit 314, and pressurized fuel sent from the fuel supply system is intermittently injected into the intake manifold 90. Note that the fuel injection valve 12 constitutes a fuel supply device in the present invention.

As described above, in a fuel injection type engine, the amount of fuel supplied to the engine is determined by the drive pulse sent from the control circuit 34 to the fuel injection valve 12.
In order to calculate the pulse width of this driving pulse, that is, the fuel injection time of the fuel injection valve 12, the control circuit 34
For example, a crank angle signal is input from the cylinder discrimination sensor 30 and engine rotation speed sensor 32 provided in the distributor 94, and an intake air amount is input from the air flow meter 2. A signal is being input. In addition, although not shown, a cooling water temperature signal from a cooling water temperature sensor, an intake air temperature signal from an intake air temperature sensor, etc. are input.

In this embodiment, the ignition system is also controlled by the control circuit 34, and the energization signal is sent from the control circuit 34 to the igniter 28.

FIG. 3 is a block diagram showing details of the control circuit 34, and here, each sensor that inputs a signal to the control circuit 34, as well as the fuel injection valve 12 and the ionizer 28 to which signals are sent from the control circuit 34, are also shown in blocks. has been done.

The control circuit 34 includes random access memory (RAM).
) 36, a read-only memory (ROM) 38,
central processing unit (CPU) 40 and first input/output boat 4
2, a second input/output port 44, and a first output port 4
6 and a second output port 48, and includes a RAM 36, a ROM 38, a C
The PU 40, the first input/output boat 42, the second input/output port 44, the first output port 46, and the second output port 48 are connected by a bus 50.

The first input/output boat 42 includes buffers 52A to 52C.
, multiplexer 54 and analog-digital (A
/D) The air flow meter 2 , the cooling water temperature sensor 24 , and the intake air temperature sensor 26 are connected via the converter 56 . The multiplexer 54 and A/D converter 56 are controlled by a command signal sent from the CPU 40 via the first input/output port 42, and sequentially convert the voltage signals from the air flow meter 2 and each sensor 24, 26 into binary data. Convert to signal.

A cylinder discrimination sensor 30 and an engine rotation speed sensor 32 are connected to the second input/output boat 44 via a waveform shaping circuit 64.
The pulse signal from the engine rotation speed sensor 32 is used to calculate the engine rotation speed and also serves as the clock for the timing counter, and the pulse signal from the cylinder discrimination sensor 30 is used to calculate the current rotation speed of the timing counter. Works as a signal. The timing signal obtained from this timing counter is sent to the CPU 40 and becomes an interrupt request signal for a fuel injection processing routine that calculates the pulse width of the drive pulse to the fuel injection valve 12.

Further, the first output port 46 is connected to the initer 28 via the drive circuit 70, and the second output port 48 is connected to the initiator 28 via the drive circuit 70.
It is connected to the fuel injection valve 12 via a drive circuit 72.

On the other hand, the ROM 38 stores in advance a main processing routine program, a fuel injection processing routine program, and other programs, as well as various data, tables, etc. necessary for these calculation processes.

According to a predetermined program stored in ROM38, C
The PU 40 instructs the A/D converter 56 to start A/D conversion for a predetermined period of time, for example, every 4 to 8 seconds, and the data representing the intake air amount, intake temperature, and cooling water temperature are ,
The data is taken into the computer by an A/D conversion completion interrupt from the A/D converter 56 and stored in the RAM 36 as it is.

In addition, the engine rotation speed data obtained based on the pulse signal generated from the engine rotation speed sensor 32 is also RA.
Stored in M36. ! FIG. 4 shows a time interrupt processing routine that is activated every 4 milliseconds.

When this program is started, first, step 101
At , the Q/N is captured. The intake air amount Q and the engine rotational speed N are both data that is taken in, calculated, and stored in the RAM 36.

Q/N is obtained by dividing the intake air amount Q by the engine speed N, and is calculated by dividing the intake air amount Q by the engine speed N.
This is used when calculating the fuel injection time in step 2.

Since Q/N is proportional to the pressure in the intake passage 20, it is used here as a value representing the degree of supercharging, that is, the supercharging pressure.

Next, in step 102, Q/N is 1. El/rev
It is determined whether the
Then, it is determined whether Q/N is greater than 1.61/rev. That is, in steps 102 and 103, the supercharging by the two superchargers 4.6 has the same number of detection levels as the number of superchargers, 1,317 rev, 1.61 /rev
It is determined whether or not this is being done excessively.

If the wastegate valve 8.10 of each supercharger 4.6 is operating normally and supercharging is not performed excessively,
Since Q/N is a value lower than 1.61/rev, both steps 102 and 103' are negative, and the process proceeds to step 117.

On the other hand, the waste gate valve 8.1 of each supercharger 4.6
0 fails and does not open until it closes, the pressure in the intake passage 20, that is, the supercharging pressure, increases abnormally in response to the opening degree of the throttle valve 92.

In this case, if Q/N exceeds 1.6 β/rev and both waste gate valves 8.10 do not open, Q/N also exceeds 1.3 It/rev. Also, if the throttle valve 92 is suddenly opened when the temperature around the engine is low and the response of the actuator 14, 16 to boost pressure is poor,
Q/N may exceed 1.61/rev.

In this way, if Q/N exceeds 1.61/rev, a negative determination is made in step 102, but step 1
03 is affirmatively determined, and the process proceeds to step 114. Also, Q
If /N exceeds 1.81/rev, an affirmative determination is made in step 102, and the process proceeds to step 111.

In step 117, the program counter C1,
-C2 is cleared to "0" and step 111.
At 114, counters C1 and C2 are each incremented. Therefore, when Q/N becomes larger than 1,812 /rev or 1.61 /rev, counter C1 or C2 is incremented every 41 υ seconds, and Q/N is incremented every 41 υ seconds.
When N becomes 1.61/rev or less, both counters C
LC2 is cleared.

Q/N months, greater than 81 /rev, step 11
When 1 is processed, it is determined in step 112 whether the counter C1 has become ``25'' or more.

When Q/N becomes larger than 1.81/rev and 0.1 seconds have passed, the process of step 111 is performed 25 times,
Since the counter C1 becomes "25", an affirmative determination is made in step 112 and the process proceeds to step 113, where the counter C1 is set to "25". However, before 0.1 second elapses, the counter C1 becomes less than "25", so a negative determination is made in step 112, and the process in step 113 is skipped.

Further, when Q/N is greater than 1-61 /rev and step 114 has been processed, it is determined in step 115 whether or not the counter C2 has exceeded rl 250J. When Q/N becomes larger than 1.6117 rev and 5 seconds have passed, the process of step 114 is changed to 1250 rev.
Since the counter C2 becomes "1250", an affirmative decision is made in step 115 and the process proceeds to step 116.
Here, the counter C2 is set to rl 250J. However, before 5 seconds elapse, the counter C2 becomes less than rl 250J, so a negative determination is made in step 115, and the process in step 116 is skipped.

As described above, by executing the time interrupt processing routine shown in FIG.
50J&;:,,,yoe, Q/N#<1.8'
When the state of being greater than Il/rev has passed for 0.1 seconds or more, the counter C1 is set to "25".

FIG. 5 shows a fuel injection processing routine activated by a timing signal from the above-mentioned timing counter, and for example, in the case of a six-cylinder engine, this routine is executed every 120 degrees of crank angle.

When this routine is started, first, in step 121, the engine speed and intake air amount stored in the RAM 36 are read, and the basic fuel injection time τp is calculated from the engine speed and intake air amount, that is, Q/N. seek. Next, in step 122, as is well known, the RAM
The fuel injection time τ is determined by correcting the basic fuel injection time τp based on the warm-up increase correction coefficient stored in the controller 36 and other correction coefficients. That is, it is determined by τ=τpXKm+Tv. Here, Km is a correction coefficient,
TV is the invalid injection time of the fuel injection valve 12. moreover,
Km is: Km = K,
(Ks +Ka Ks ・---------・)
It is calculated by the sum or product of each correction coefficient KI, Kg. For each correction coefficient +, Kz・-・
. . . are, as is well known, a warm-up increase correction coefficient, a post-start increase correction coefficient, etc.

In the next step 123, it is determined whether the counter C1 is greater than "25", and in step 124, it is determined whether the counter C2 is greater than rl 250J. If the counter C1 is equal to or greater than "25" or the counter C2 is equal to or greater than r1250J, step 123 or step 1
24 is affirmatively determined, and in step 125, the fuel injection time τ is set to "0". However, counter C1 is "
25" or more, and the counter C2 is also rl 25.
If it is not greater than or equal to 0J, step 123.1
24 are both negative, and the process of step 125 is skipped.

In step 126, data regarding the fuel injection time determined in this way, that is, the fuel injection pulse width, is converted into a signal for driving the fuel injection valve 12, and is supplied to the fuel injection valve 12. At this time, if the process of step 125 is skipped and the fuel injection time τ is not set to "0",
A predetermined amount of fuel is injected according to the operating state of the engine, but step 125 is processed and the fuel injection time τ is
0, no fuel injection is performed at all, and a so-called fuel cut is performed.

In addition, in the flowcharts of FIGS. 4 and 5,
The processing in steps 101 to 103 corresponds to the overcharging detection means of the present invention, and the processing in steps 11 to 117 is as follows:
This corresponds to the delay means of the present invention, and the processing of steps 121 to 126 corresponds to the fuel supply amount control means of the present invention.

FIG. 6(A) is a graph for explaining the above-mentioned control contents, and shows the engine rotation speed on the horizontal axis and the Q/N on the vertical axis. If Q/N remains greater than 1.61t/rev for 5 seconds or more, counter C2 will change to r1250J.
Since the fuel injection time τ is set to rOJ, a fuel cut is performed, and if the state where Q/N is greater than 1.81/rev continues for more than o, i seconds, the counter C1
is set to "25" and the fuel injection time τ is set to "0", so a fuel cut is performed. Note that this control is performed regardless of changes in engine speed.

Therefore, when one of the waste gate valves 8.10 of the two superchargers 4.6 fails and remains closed and does not open, the supercharging pressure increases in accordance with the opening degree of the throttle valve 92. Therefore, Q/N becomes larger than 1-61/rev, and when this continues for 5 seconds, a fuel cut is performed and the engine is stopped. In addition, two superchargers4.
Both of the waste gate valves 8 and 10 in No. 6 are broken and do not open (when this occurs, the boost pressure increases in accordance with the opening degree of the throttle valve 92, so the Q/N is 1.8).
j! /rev and continues for 0.1 seconds, a fuel cut is performed and the engine is stopped.

However, the temperature around the engine is low and
y'-) /, /L/7"8.10 (D79 fs:
Z-1'14.16 has poor responsiveness to changes in supercharging pressure, and when the opening of the throttle valve 92 is suddenly increased, the supercharging pressure temporarily increases, and at this time, Q/
Even if N becomes larger than 1.61/rev, this does not continue for more than 5 seconds, so there is no possibility that the fuel will be cut off by mistake and the engine will be stopped.

FIG. 6(CB) is a graph similar to FIG. 6(A) for explaining the control contents in the conventional case where there is only one detection level. In this case, if the Q/N remains larger than the set value for a predetermined period of time, fuel cut is performed. For this reason,
When the set value is set to 1.81/reν, each turbocharger 4
．． When only one of the 6 waste gate valves 8.10 fails and does not open, the Q/N is 1.8 A.
/ rev is not reached easily, so even though one of the waste gate valves 8.10 is out of order, the fuel is not cut and the engine is adversely affected. On the other hand, if the set value is set to 1.6 e/rev and the predetermined time is relatively long, both waste gate valves 8.10 of the two superchargers 4.6 will fail. When it does not open, the boost pressure rises quite rapidly, which can have an adverse effect on the engine before the fuel is cut. Also, if the predetermined time is made relatively short, even if both wastegate valves 8.10 are not malfunctioning, slow/
) The supercharging pressure temporarily increases in response to the sudden opening of the fuel valve 92, resulting in a fuel cut and the engine being stopped.

Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and includes various embodiments within the scope of the claims. For example, the boost pressure may be detected directly by a pressure sensor. Further, the fuel supply device may be a carburetor.

〔Effect of the invention〕

As described above, according to the present invention, even if the supercharging pressure does not become too high, if the duration is long, it is assumed that the supercharger has failed and the amount of fuel supplied is set to zero, and even if the supercharging pressure does not become high enough. For example, even if the duration is short, the amount of fuel supplied will be reduced to zero as a result of a turbocharger failure, so regardless of the number of failed turbochargers, the engine will be shut down before it has a negative impact on the engine. Moreover, the increase in supercharging pressure when there is a delay in response of the waste gate valve at low temperatures does not become very high and the duration is short, so this can be mistakenly detected as a fault in the supercharger. This eliminates the problem of stopping the engine for no reason.

[Brief explanation of the drawing]

FIG. 1 is a claim correspondence diagram, FIG. 2 is a system configuration diagram of an embodiment of the present invention, FIG. 3 is a block diagram of the control circuit in FIG. 2, and FIGS. 4 and 5 are FIG. 3 is a flowchart showing part of the program contents of the microcomputer, and FIG. 6 is a graph for explaining the control contents in the above embodiment. 2...--Air flow meter 4.6-----1-Supercharger 8.10--Waste gate pulp 12
--- Fuel injection valve 14, 16 --- Actuator 18 --- Engine body 20 --- Intake passage 22 --- Exhaust passage 30 --- Cylinder discrimination sensor 32--Engine speed sensor 34---Control circuit 36--RAM 38--ROM 40-------CPU 92-------- Throttle valve applicant Toyota Motor Corporation Saki site Figure 3 y Figure 4 Figure 5 W

Claims (1)

[Claims] 1. In an engine equipped with a plurality of superchargers, over-supercharging detection means has the same number of detection levels as the superchargers and detects that supercharging is excessively performed exceeding each detection level; The amount of fuel supplied from the fuel supply device to the engine is controlled according to the operating state of the engine, and when excessive supercharging is detected by the overcharging detection means,
A fuel supply amount control means that sets the fuel amount to zero, and a period from when excessive supercharging is detected by the overcharging detection means to when the fuel supply amount control means sets the fuel amount to zero. A supercharged engine is provided with a delay means for delaying by a predetermined time, the predetermined time being set for each detection level in the over-supercharging detection means, and the delay means being made longer as the detection level is lower. Fuel supply amount control device.