JPS5910747A - Fuel cut device for electronically controlled engine - Google Patents

Abstract

PURPOSE:To reduce variation of the output torque of an engine by cutting fuel when synchronous fuel injection amount is less than a reference value. CONSTITUTION:In step 66 is read an engine speed Ne. In step 67 is obtained the reference fuel injection time taucut from the engine seed Ne. In step 68 is read synchronous injection time tau, and in step 69 is judged whether or not tau<taucut. When tau<taucut and the engine speed Ne>=N1, fuel is cut. When Ne<N1 even though tau<taucut, fuel is not cut. When tau>=taucut, fuel is not cut. Thus, the variation of the output torque of the engine can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel cut device for an electronically controlled engine that stops supplying fuel during a deceleration period to improve exhaust gas purification and fuel consumption efficiency.

In conventional fuel cutoff devices, fuel cutoff is performed in response to turning on and off of an idle switch that detects the idling opening of a throttle valve.

The idle switch is a mechanical type that opens and closes the contacts in conjunction with the shaft of the throttle valve, ensuring a predetermined contact pressure.
It has been turned on since.

Therefore, in the conventional fuel cutoff device, especially in the case of fuel cutoff in the low engine speed region, the fuel cutoff is started before the engine's output torque becomes sufficiently close to the engine's friction torque, or the fuel cutoff is started before the engine's output torque becomes sufficiently close to the engine's friction torque, or the fuel cutoff is started before the engine's output torque becomes sufficiently close to the engine's friction torque. If it moves, the throttle valve is 1
The fuel supply is resumed after the opening degree reaches ~2°, and the shock at the start of fuel cutoff and when transitioning from deceleration to acceleration increases. Indeed, the fact that the fuel 1 cutoff is performed when the throttle valve is not fully idling but at a slight opening narrows the engine's low-speed, light-load operating range.

An object of the present invention is to eliminate such drawbacks of the conventional fuel cutoff device, which occurs when the idle switch is turned on from an opening slightly larger than the idling opening.

In order to achieve this object, the present invention provides an electronically controlled engine in which the synchronous fuel injection amount of fuel supplied from the injection valve to the intake system in synchronization with the rotation of the engine is reduced as a function of the intake air flow rate. In the fuel cutoff device, a reference value, which is a function of the engine rotational speed, is calculated from the detection shift ξ1 hole rotational speed, and if the periodic fuel injection meter is less than the reference value, the fuel is cut off, and the same 1υ1 fuel If the injection meter is below the standard value, it will supply fuel I to the intake system.

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

FIG. 1 is a schematic diagram of the entire Y1 system to which the present invention is applied. The electricity sucked in from the air cleaner 1 is sent to the air flow meter 2, throttle valve 3, Zano tank,
1, an intake passage 12 including an intake boat 5 and an intake valve 6
6, which is sent to the combustion chamber 8 of the engine body 7 via the throttle valve 6.
is linked to accelerator pedals 1 and 3 in the driver's cab. A combustion chamber 8 is defined by a cylinder head 9, a cylinder block 10, and a piston 11, and the exhaust gas produced by the combustion of the air-fuel mixture passes through a control valve 15, an exhaust boat 16, an exhaust branch pipe 17, and an exhaust pipe 18. released into the atmosphere via The bypass passage 21 connects the upstream side of the throttle valve 3 and the surge tank 4.
The bypass flow control valve 22 is connected to the bypass passage 2.
The flow cross-sectional area of 1 is controlled to maintain a constant engine rotational speed during idling. In order to suppress the generation of nitrogen oxides, exhaust gas is guided to the intake system by υ1 gas recirculation (EGR).
) Passage 2:3 ij, exhaust branch' (τ17 and ther/・4
connection 4, and perform on-off valve type exhaust gas recirculation (
EGR) control valve 2・Itfot: Opens and closes the EGR passage 2;) in response to electric pulses. )! Water temperature sensor 281 (1, installed in the air flow meter 2 to detect the intake air temperature, throttle position sensor 29 t/i, throttle valve: 3 opening degree), water temperature sensor 30 (4 cylinder block 10) A well-known air-fuel ratio sensor 31 as an oxygen concentration sensor is attached to the collecting part of the 411 air branch pipe 17 to detect the oxygen concentration in the collecting part, and detects the cooling water temperature, that is, the engine temperature. The angle sensor 32 detects the crank angle of the crankshaft from the rotation of the shaft of the power distributor 33 connected to the crankshaft (not shown) of the engine body 7; 3.1.
The outputs of 29.30.31.32 are sent to the electronic control unit 40. Fuel and injection valves are provided near each intake boat 5 in correspondence with each cylinder, and the pump 42 supplies fuel from a fuel tank 43 to the fuel injection valves through a fuel passage 44.

Electronic jlil control system 4 (1iJ, burning based on one person's strength bow from each sensor (reciting jet QA'ti'i 7
, Blue 1 ■ Shida Fuel O'・1 injection Q1.5+4 sends the first fuel injection pulse with a Tsukimi and Shibu pulse width to the fuel injection valve 41-8. E-r': Il monk 1 device = lO11, control valve 22 for bypass flow, F: G R:li'l visit valve 2.1. A, Ignition device/1G open side). Ignition device bar 4 (i
Tertiary Th1ll lql of the spotting coil: Distributor 3;
3-\Connected. .

Figure 2 (1) is a block diagram of the internal components of the electronic control unit. CPU 5, ROM 57, RAM
58 , 541 , a multiplexer (A/I) (analog/tezotal) converter 60 , and an I10 (human output) ink face 61 are connected to each other via a bus 62 . RAM5!1←l1 is connected to the auxiliary power source, and even when the ignition switch is opened and the engine is stopped, a predetermined amount of power is supplied and the memory can be retained.

Analog signals from the knee flow meter 2, intake temperature sensor 28, water temperature sensor 30, and air-fuel ratio sensor 31 are A.
/D converter 60. Throttle position sensor 2 (
] and the output of the crank angle sensor 32 are sent to the I10 interface 6I, and the bypass flow control I fp 22
, EGR control valve 24, old fuel injection valve, and ignition system 4
al(, J, an input signal is sent from the input/output interface 61.

FIG. 3d is a flowchart of the program of the present invention. In step 66, the engine rotational speed Ne is read. The engine rotational speed Ne is detected from human power from the crank angle sensor 32. In step 67, cut is calculated using the standard fuel injection time for fuel cutoff.

τc u t l: As shown in FIG. 4, it is a function of Ne and is defined by the following equation.

τcut=Ne
The synchronous fuel injection time τ listed in onst is constant. Note that the synchronous fuel injection time τ is the same as the engine rotation speed.
lJ+ means the time during which the injection valve 11 injects fuel, and the injection valve old is kept fully open.

In FIG. 4, the horizontal axis is the engine rotational speed Ne, the vertical axis is the engine output torque T, and the iso-tau line is in one line with respect to the horizontal axis. The friction torque of an engine is related to Ne, and Ne
When it is small, it decreases by 1'-1 (because friction torque is expressed as a negative value). The engine output torque T, which is set along the line τcut(r, J friction) · torque, is negative, which means that the torque is being transmitted from the drive wheels to the engine force.

Step (58) reads the same amount injection time τ. τ is a function of the intake air flow rate - Q.
- It can be detected directly from the meter 2 or indirectly from the negative side of the intake pipe. In step 69, it is determined whether d, τ<τcut, and if it is, the process proceeds to step 70, and τ,
If τcut, proceed to step 76 and set the flag F cu
Set t to 0. In step 70, it is determined whether Ne is NI or not, and if Ne is Q-3Nl, step 74
Step 71 sets the flag F cut to 1, and if N<N1, the flow advances to step 71. Nl1J:, 2000 r, p,
m.

For example, l300r, p, m. In step 71, it is determined whether or not N-1-N2 and F cut-1. If N-;-N2 and F cut-=1, Progera 11 is terminated and N(N2 or iJ,'
If ut = 0, proceed to step 76 and p cut
= O. N2 is less than or equal to I 800 r, p, +n, Nl - N2 /100, and N2 (
dFor example! I F3(] r, p, m, Fc
In the case of u Hi 1, it is practical to shut off the fuel 1;l, and F C1l
In the case of t-0, fuel is supplied from the old fuel injection valve. A hysteresis regarding the engine rotational speed is provided for the implementation of the fuel cutoff.If Ne(Nl), the fuel cutoff will not be started, but if Ne is
It continues decreasing to 2 hours. In the conventional fuel cutoff device, the fuel cutoff starts when the idle switch is turned off from OFF, as shown by the broken line in Fig. 4, that is, when the throttle valve 3 is opened 1 to 2 degrees before reaching the idling opening. As a result, the engine output torque T changed significantly from the position of the broken line to the position of friction torque (the two-dot button line), and a large impact was generated. In the present invention, the fuel cutoff is performed after the engine output torque T sufficiently approaches the friction torque at the engine rotational speed Ne at that time, so the change in the engine output torque accompanying the start of the fuel cutoff is small, and the impact is suppressed. be done.

In Figure 5, Ne is Nea, Neb, Ne, respectively.
c shows the relationship between the engine output torque T and the throttle valve opening in the case of Nea (Neb (Nec)). In the present invention, i-1, the idle switch is turned on U (even after the second opening, the fuel j'-1 continues to be supplied, and the engine's output l/ruq is sufficient for the friction torque). The fuel 81 cut-off starts after the approach, and this feature becomes more pronounced as Ne is smaller.

FIG. 6 shows changes over time in vehicle speed and engine output torque when the throttle valve is gradually closed to the idling opening and then gradually opened from the idling opening. The solid line shows the present invention, and the broken line shows the change in the conventional device. t
1 and t2 are the times at which fuel cutoff is started in the conventional device and the present invention, respectively, and t3 and t4 are the times at which fuel supply is restarted in the present invention and the conventional device, respectively. During fuel cutoff, the engine speed decreases, so the engine output increases over time. According to the present invention, the fuel cutoff is performed after the output torque of the engine is sufficiently reduced;
However, during acceleration d1, the fuel supply is quickly resumed before the throttle valve opening degree is 1 to 2 degrees when the idle switch is turned off, so the change in engine output torque due to the start and end of fuel cut-off is reduced, and the impact is reduced. is suppressed.

Thus, according to the present invention, the synchronous fuel injector calculated as a function of the intake air flow rate is compared with a reference value calculated as a function of the engine speed to determine whether to perform a fuel cutoff. It is possible to reduce the amount of intermittent change in engine output torque accompanying the start of fuel cutoff and resumption of fuel supply, thereby suppressing impact. Since fuel supply can be maintained at extremely small openings, such as when the idle switch is turned on, the operating range of the engine at low loads can be expanded.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the entire electronic control engine to which the present invention is applied, FIG. 2 is a block diagram of the electronic control device shown in FIG. 1, and FIG.
Figure 4 is a flowchart of a program based on the present invention.
The figure shows the implementation range of fuel cutoff, Figure 5- is a graph showing the relationship between the throttle valve opening and the engine output torque comparing the present invention and the conventional device, and Figure 6 shows the relationship between the throttle valve opening and the engine output torque. Slow force 11 speed-
This is a graph that shows the time changes in heavy speed, throttle valve opening, and engine output torque when shifting. 2. Flow meter, 7. Engine body, 10.
Electronic control unit, 41・Fuel injection valve.

Claims (1)

[Scope of Claims] 1. A fuel cutoff system for an electronically controlled engine in which a synchronous fuel injection amount of fuel supplied from an injection valve to an intake system in synchronization with engine rotation is calculated as a function of an intake air flow gutter. A reference value, which is a function of speed, is calculated from the detected engine rotational speed, and if the synchronous fuel injection amount is less than the reference value, fuel is cut off, and if the synchronous fuel injection amount is less than or equal to the reference value, fuel is taken into intake. A fuel cutoff device for an electronically controlled engine, characterized by supplying fuel to the system. 2. Claim 1, characterized in that the fuel injection pulse to be sent to the injection valve has a pulse width corresponding to the synchronous fuel injection amount, and the pulse width is compared with the reference value.
Fuel cutoff device as described in section. 3. The fuel cutoff device according to claim 1 or 2, wherein the reference value is set as a function that decreases as the engine rotational speed increases. 4 The reference value τcut is determined by the following formula % formula % Ne: engine rotation speed, K: positive constant, τcon
st: A constant. 4. The fuel cutoff device according to claim 3, wherein the fuel is discharged from the fuel cutoff device.