JPS6365145A - Fuel control device for automobile engine - Google Patents

Abstract

PURPOSE:To prevent a speed reduction shock by carrying out a speed reducing and quantity increasing correction when gears are connected and to prevent the rising up of engine speed by limiting the speed reducing and quantity increasing correction when gears are not connected. CONSTITUTION:Signals from an engine speed sensor 20, a throttle opening sensor 23, an idle switch, a gear switch 28, etc. are inputted into a control device 26, to control a fuel injection quantity from an injector 16. In a condition that an idle switch is on, that the engine speed is in a speed-reducing and quantity-increasing engine speed zone, and that gears are connected, a speed reducing and quantity increasing correction is carried out. When gears are not connected, the speed reducing and quantity increasing correction is suspended. Thereby, a speed reduction shock can be prevented when gears are connected while the rising up of engine speed can be prevented when gears are not connected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel control device for an automobile engine, and more particularly to a fuel control device that corrects the fuel injection amount during deceleration and increase.

(Prior Art) In recent years, automobile engines are equipped with electronically controlled fuel control devices to precisely control the amount of fuel injected from an injector based on engine operating conditions, cooling water temperature, intake temperature, etc.

Furthermore, this type of fuel control device generally cuts fuel when the vehicle decelerates to prevent incomplete combustion, protect the catalyst, and save fuel, thereby preventing deceleration shock and improving combustibility during the transition to an idle state. In order to ensure this and prevent engine stall, the fuel injection amount is corrected for deceleration and increase.

For example, Japanese Patent Application Laid-Open No. 58-222930 discloses that the inheritance time of the idle switch ON is detected, and 1) when one hour is less than a predetermined value, the value of the deceleration increase is set smaller than when the time is more than the predetermined value. A fuel control system with a 100% reduction in fuel consumption is described.

(Problems to be Solved by the Invention) In the conventional fuel control device for an automobile engine, the fuel injection amount is corrected by deceleration increase ffi +1 m regardless of whether the gear of the transmission is engaged or not.

Therefore, if the deceleration increase correction is performed when the clutch is disengaged and the gear is not connected, there is a problem in that the engine speed will suddenly increase because the engine load is very small.

(Means for solving the problems) The automobile engine control i'JIl device according to the present invention includes:
As shown in the functional block diagram in Figure 1, among the engine operating ranges determined by engine speed and load, the fuel injection amount is decelerated and increased in a predetermined operating range adjacent to the idle range and higher than the idle range. In the fuel control gW for an automobile engine, a detection means for detecting whether a gear of the transmission is in a connected state or a disconnected state is provided, and based on the output from the detection means, when the gear is in a disconnected state, A correction limiting means is provided for limiting the deceleration/increase correction described above.

(Function) In the fuel control device for an automobile engine according to the present invention, a deceleration increase correction is made to the fuel injection amount in a predetermined operating region of the engine that is adjacent to the idle region and on the higher rotation side than the idle region. However, when the detection means detects that the gear of the transmission is in a disconnected state, the correction restriction means restricts the deceleration increase correction based on the detection result.

In other words, when the gears are in the connected state, deceleration shock is likely to occur (engine stall is likely to occur when shifting to the idle region), so the deceleration increase correction prevents a sudden decrease in torque and ensures combustion performance.

On the other hand, when the gear is in the disconnected state, the engine load is small and engine stall is less likely to occur, so by limiting the deceleration increase correction, the engine speed is prevented from rising.

(Effects of the Invention) According to the fuel control device for an automobile engine according to the present invention, as explained above, deceleration shock can be reliably prevented by correcting the deceleration increase when the gear is engaged. By limiting the deceleration increase correction when the gear is not engaged, it is possible to reliably prevent the engine speed from rising.

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

This embodiment is an example in which the present invention is applied to a 4-stroke, 4-cylinder, vertical fuel-injection engine for an automobile.

As shown in FIG. 2, a combustion chamber 4 is formed by a cylinder block 1, a cylinder head 2, and a piston 3, an intake valve 6 opens and closes the downstream end of an intake boat 5, and an exhaust valve 6 opens and closes the downstream end of an exhaust port 7. An air cleaner lO is provided at the upstream end of an intake passage 9 connected to the intake boat 5, and a measuring plate-type intake air amount sensor 1) and a turbocharger are installed in the intake passage 9 in order from the upstream side. 1
A compressor 12b, an intercooler 13, a throttle valve 14, and a surge tank 15 are installed at the lower end of each branched intake pipe of the intake manifold portion of the intake pipe forming the intake passage 9, which is directed toward the intake boat 5. An injector 16 that injects fuel is installed.

On the other hand, a turbocharger 12 is located in the middle of the exhaust passage 17.
A turbine 12a is provided.

Furthermore, as various sensors other than the intake air amount sensor 1), a water temperature sensor 18 for detecting the temperature of cooling water in the walk jacket of the cylinder block 10 is installed in the cylinder block 1.
For example, a rotation speed detection sensor 20 for electromagnetic pickup 2 is attached to the crankshaft 19 and outputs a rotation speed signal (crank angle signal) every time the crankshaft 19 rotates 180 degrees. A first intake temperature sensor 21 is interposed in the intake passage 9 to detect the intake temperature, and a second intake temperature sensor 2 is installed in the surge tank 15 to detect the intake temperature after supercharging and after being cooled by the intercooler 13.
A throttle opening sensor 23, such as a potentiometer 2, for detecting the opening of the throttle valve 14 is provided in conjunction with the valve shaft of the throttle valve 14.

Furthermore, the throttle valve 14 is provided with an idle switch (path shown) that is turned on until the throttle valve 14 opens by a set amount when the accelerator pedal is slightly depressed, and turned off when the throttle valve 14 is opened by more than the set amount.

A control unit 12G is provided to control the distributor 24, injector 16, and warning lamp 25 in response to detection signals from the sensors 1), 18, 20 to 23, etc., and this control unit 26 is connected to an inhibitor switch. 27, a signal from a gear switch 28 attached to the transmission and detecting the gear connection state, and a voltage signal from the battery are also output.

As shown in FIG. 3, the control unit 26 includes an A/D converter 26a that receives detection signals from the sensors 1), 18, 20 to 23 and the battery, performs A/D conversion, and outputs the signals to the CPU 26C. and rotation speed detection sensor 20
and an input interface 2 that receives signals from the switches 27, 28, etc. and outputs the signals to the CPU 26C.
6b, CPU <central processing unit) 26C, and ROM
(Read-Only Memory) 26d, RAM (Random Access Memory) 26e, and an output interface 26f that outputs drive signals to the injector 16, distributor 24, etc. in accordance with the output signal from the CPU 26c. A/D converter 26a, input interface 26b, ROM 26d, and RAM 26
e and the output interface 26f are connected to the CPU 26C via the control bus, address bus, and data bus, respectively.
It is connected to the.

The ROM 26d stores in advance a control program for fuel injection amount control, a control program for ignition timing control, a memory map, and other control programs, which will be described later.

The RAM 26e is provided with a plurality of memories (temporary data storage memory, flag memory, counter memory, etc.) for temporarily storing various data as needed.

Next, a flowchart of the fuel control routine executed by the control unit 26 will be described with reference to FIG.

In the figure, 81 to S22 indicate each step. First, when control is started with engine startup, initialization such as clearing the memory is executed at SL, and then 82
At step 83, the intake air amount signal is read, and then at step 83, the intake air amount Q1 per cylinder is calculated using the intake air signal.

Next, at 84, the engine rotation speed N calculated using the rotation speed signal from the rotation speed detection sensor 20 and stored in the memory is read by interrupt processing, and then at 85, the basic injection time T, - is changed to T. , = is calculated using the formula -Q, /N (where K is a predetermined constant) and is written as jQ.
be done. This basic injection time TP corresponds to the basic injection amount for each cylinder, and represents the pulse width of the injection pulse output to the injector 16.

Next, in S6, the throttle opening signal θ from the throttle opening sensor 23 is read and stored.

Next, at 87, it is determined whether the idle switch provided on the throttle valve 14 is ON (see FIG. 5).
When it is ON, it moves to S8, and when it is OFF, it moves to S2.
Transition to 0.

When the idle switch is ON, it is determined in S8 whether the engine speed N is equal to or higher than the lower limit rotation speed N8 for deceleration and increase, and when N≧N, the process moves to S9, and when N≧ND, the process moves to S18.

Next, in 89, it is determined whether the engine speed N is equal to or higher than the deceleration increase upper limit speed N6, and if N<Nc, the SIO
When N≧NC, the process moves to 31G.

Result N of determination in S8 and S9 above. ≦N<When NC, it is determined that the engine operating state is in the deceleration/increase region.

Next, in Sll, it is determined whether the vehicle is an M/T vehicle, that is, whether or not it is equipped with a manual transmission. M
When using a common microcomputer for the control unit of /T vehicles and A/T vehicles (vehicles equipped with automatic transmissions), the CPU 26 is used for MZT vehicles and A/T vehicles.
Since the settings of boat c are different, whether or not it is an M/T vehicle is determined from the settings of the boat.

As a result of the above determination, if the vehicle is an M/T vehicle, the process proceeds to S12, and if the vehicle is an A/T vehicle, the process proceeds to S15. and,
In the case of an M/T vehicle, it is determined in S12 whether or not the gear of the transmission is in the connected state, and if the gear is in the WI'FM state, the process moves to S13, and if the gear is not in the connected state, S12 is determined.
Move to 15.

In the case of gear connection, deceleration increase correction is performed to prevent deceleration shock and engine stall when transitioning to an idle state.

That is, in S13, the injection time T is T=TP
Cii + Cn ) + τ calculation formulas.

However, the above C8 is the deceleration increase J1) correction, C and 4 are the water temperature corrections that are corrected during warm-up when the cooling water temperature is below a predetermined value, and C1l is the battery correction that is corrected when the battery voltage is below a predetermined value. The water temperature correction C,1 is calculated from a predetermined memory map or calculation formula that uses the cooling water temperature as a parameter, the deceleration increase correction CD is a predetermined constant, and the battery correction τ8 is calculated using a memory map that uses the battery voltage as a parameter. It is calculated from a calculation expression.

If the result of the judgment in Sll is that it is an A/T vehicle or S
As a result of the determination in Step 12, M/] If the gear of the vehicle is not connected, the deceleration increase correction is canceled by setting C0-0 in S15, and the process moves from S15 to 313.

In other words, when the gear is not engaged, the load on the engine is extremely small, so if the engine is compensated for the increase in deceleration, the engine speed will suddenly increase and increase when the engine shifts to the idle state, so the correction for the increase in deceleration is canceled. .

The process moves from S13 to S14, and in S14, when the injection timing comes, the injector is driven by outputting an injection pulse with a pulse width of injection time T determined in any step of S13, S19, or S21.322. Then, the process returns from S14 to 82.

On the other hand, if N≧N as a result of the determination in S9, S
At 31G, it is determined that the engine operating state is in the fuel cut region (see Figure 5), and then at 31G
In S17, the drive of the injector is stopped, and the process returns from S17 to S82.

On the other hand, if the result of the determination in S8 is not N≧N, it is determined in 318 that the operating state of the engine is in the idle region, and then in 319 the injection time T in the idle region is determined by the calculation formula of T=T, +τ3. calculated, S1
Transition from 9 to 314.

Furthermore, as a result of the determination in S7, the idle switch is set to O.
In the case of FF, the process moves to S20, where it is determined whether the rate of increase in throttle opening dθ/dt is equal to or greater than a predetermined value A, and dθ/
When dt≧A, it is determined that the state is accelerating, and in this case, in S21, the injection time T is determined as T=Tr (1”C,
, "CA+Cy) + τ3, 321
Then, the process moves to 314.

However, the above CA is an acceleration correction for improving the output during acceleration and ensuring acceleration responsiveness, and the above acceleration correction CA is stored in advance in the ROM in the form of a memory map or an arithmetic formula using the increase rate of the throttle opening as a parameter. This is a stored input, and qualitatively the value becomes larger as the rate of increase in throttle opening increases.

In addition, the above C6 is an enrich correction that changes the air-fuel ratio that was lean-controlled in the idle state to the stoichiometric air-fuel ratio (14,7) or higher when the idle state is not idle, and this enrich correction cE is performed when the idle switch is turned off. OF
For the region F, the ROM 26 d
is stored in.

As a result of the determination in S20, if dθ/dt≧A, the state is not accelerated, so the process moves to S22, where the injection time T is calculated using the formula T=TP (1+CW +CE)+τ, and the process moves to S14.

Incidentally, the routine of S2 to S22 is repeatedly executed every minute time of several tens of m5ec.

As explained above, by performing the deceleration increase correction when the gear is engaged, it is possible to prevent deceleration shock and ensure combustion performance when transitioning to the idle region. By canceling the slow increase correction when the gear is not engaged, it is possible to prevent the engine speed from rising when the engine shifts to the idle region.

[Brief explanation of the drawing]

Of the drawings, FIG. 1 is a functional block diagram of the present invention, and FIGS.
Fig. 5 shows an embodiment of the present invention, Fig. 2 is an overall configuration diagram of an engine fuel control device, Fig. 3 is a configuration diagram of a control system such as a control unit, and Fig. 4 is a configuration diagram of a control system such as a control unit. A schematic flowchart of the fuel control routine, FIG. 5 is an explanatory diagram showing each region of the engine operating region. 1)... Intake air amount sensor, 16... Injector, 20... Rotation speed detection sensor, 26... Control unit. Patent applicant Mazda Motor Corporation Figure 1

Claims (1)

[Claims] (1) An automobile engine in which the fuel injection amount is decelerated and increased in a predetermined operating region adjacent to the idle region and on the higher rotation side than the idle region among the engine operating regions determined by engine speed and load. In the fuel control device, a detection means for detecting whether a gear of the transmission is in a connected state or a disengaged state, and a correction limit that limits the deceleration increase correction when the gear is in a disengaged state based on an output from the detection means. 1. A fuel control device for an automobile engine, comprising: means.