JPS58135345A - Cutoff method of fuel for internal-combustion engine - Google Patents

Abstract

PURPOSE:To check possible impact attendant with the resumption of fuel supply by setting the rotation speed of the engine at a smaller value in the feed back of fuel to stop the fuel cutoff when the vehicle speed exceeds a specified value or a brake is in operation than other cases. CONSTITUTION:First, when detecting that a throttle valve 3 is at an idling opening from an output of a throttle sensor 29 during the operation of the engine, a controller 40 determines whether the rotation speed Ne of the engine exceeds the minimum value Nc(about 2,000rpm) for starting the fuel cutoff or not from an output of a vehicle speed sensor 35 and outputs a fuel cutoff signal to a fuel injection valve 41 when YES. Subsequently, it determines whether the rotation speed Ne exceeds the value Nh(about 1,800rpm) for stopping the fuel cutoff or not and then, determines whether or not the vehicle speed V exceeds a specified value Vo when NO. When coming up with NO, it stops the fuel cutoff, namely, resume the fuel supply, under the condition that, the brake is in operation and the rotation speed Ne is below Nl (about 1,000rpm).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel cut method for an internal combustion engine that improves fuel consumption efficiency and emission of harmful components by cutting off fuel supply to the intake system during the deceleration period of the internal combustion engine. .

In this fuel cutoff method, fuel cutoff is performed by detecting the deceleration period from a throttle sensor that detects the opening of the throttle valve and an engine rotation speed sensor (crank angle sensor). In this method, the fuel return engine rotational speed at which the fuel cutoff is stopped is set to be constant regardless of the vehicle speed and the operating state of the brake system. In order to further improve fuel consumption efficiency, it is advantageous to set these engine speeds to small values to increase the fuel cutoff period, but when setting the fuel return engine speed to a small value, There is a problem in that the shock that occurs when the fuel supply is restarted becomes larger.

An object of the present invention is to provide a fuel cutoff method for an internal combustion engine that can increase the fuel cutoff period while suppressing the generated shock.

In order to achieve this object, the fuel cutoff method for an internal combustion engine of the present invention provides that, at high vehicle speeds or when the braking brake is in operation, the shock caused by the vehicle when the fuel is restored is due to the large inertia of the vehicle or the braking force acting on the vehicle. Focusing on the fact that the vehicle speed is more than a predetermined value or the braking device is operating, the fuel return engine rotational speed at which the fuel cutoff is canceled is set to a smaller value than in other cases.

(2) The present invention will be described in detail with reference to the drawings.

FIG. 1 is an overall schematic diagram of an electronically controlled fuel injection engine to which the present invention is applied. Air taken in from the air cleaner 1 is sent to the combustion chamber 8 of the engine body 7 through an intake passage 12 that includes an air flow meter 2, a throttle valve 3, a surge tank 4, an intake port 5, and an intake valve 6. The throttle valve 6 is linked to an accelerator pedal 13 in the driver's cab. The combustion chamber 8 is divided by a cylinder head 9, a cylinder block 10, and a piston 11, and the exhaust gas generated by combustion of the air-fuel mixture is passed through an exhaust valve I5, an exhaust port 16, an exhaust branch pipe 17,
and is discharged to the atmosphere via the exhaust pipe 18. The bypass passage 21 connects the upstream side of the throttle valve 3 and the surge tank 4, and the bypass flow rate control valve 22 controls the flow cross-sectional area of the bypass passage 21 to maintain a constant engine rotational speed during idle link. An exhaust gas recirculation (EGR) passage 23 that guides exhaust gas to the intake system in order to suppress the generation of nitrogen oxides is
The exhaust branch pipe 17 and the surge tank 4 are connected, and an on-off valve type exhaust gas recirculation (EGR) control valve 24 opens and closes the EGR passage 23 in response to electric pulses. The intake air temperature sensor 28 is provided in the air flow meter 2 to detect the intake air temperature, and the throttle position sensor 29,
The opening degree of the throttle valve 3 is detected. The water temperature sensor 30 is attached to the cylinder block 10 to detect the cooling water temperature, that is, the engine temperature, and the air-fuel ratio sensor 31, known as an oxygen concentration sensor, is attached to the collecting part of the exhaust branch pipe 17 to detect the oxygen concentration in the collecting part. The crank angle sensor 32
detects the crank angle of the crankshaft from the rotation of the shaft 340 of the power distributor 33 coupled to the crankshaft (not shown) of the engine body 7, and the vehicle speed sensor 35 detects the rotational speed of the output shaft of the automatic transmission 36. . These sensors 2 , 28 , 29
, 30 , 31 , 32 , 35 and the voltage of the storage battery 37 are sent to an electronic control unit 40 .

A fuel injection valve 41 is provided near each intake port 5 in correspondence with each cylinder, and a pump 42 sends fuel from a fuel tank 43 to the fuel injection valve 41 via a fuel passage 44.

The electronic control unit 40 calculates the fuel injection amount as a function of the input signals from each sensor, and (4) sends an electric pulse with a pulse width corresponding to the calculated fuel injection amount to the fuel injection valve 41. The electronic control device 40 also controls the bypass flow control valve 22, the EGR control valve 24, the solenoid 45 of the automatic transmission hydraulic control circuit, and the ignition device 46. The secondary side of the ignition coil of the ignition device 46 is connected to the power distributor 33 .

FIG. 2 is a block diagram of the inside of the electronic control device. C.P.
U (central processing unit) 56, ROM (read-only storage) 57, RAM (direct access storage) 58,
A C-RAM (complementary RAM) 59, an A/D (analog/digital) converter with multiplexer 60, and an input/output interface 61 are connected to each other via a bus 62. The C-RAM 59 is connected to an auxiliary power source, and is supplied with a predetermined amount of power even when the ignition switch is opened and the engine is stopped, so that the memory can be retained. Analog signals from the air flow meter 2, intake temperature sensor 28, water temperature sensor 30, and air-fuel ratio sensor 31 are sent to an A/D converter 60. Throttle position sensor 29, crank angle sensor 32, and vehicle speed sensor 35
Output (5) Power is sent to the input/output interface 61 , and the bypass flow control valve 22 , EGR control valve 24 , solenoid 45 , and ignition device 46 are sent input signals from the input/output interface 61 .

FIG. 3 is a flowchart of a program implementing the present invention. In step 65, it is determined whether the idle switch is on, that is, whether the throttle valve 3 is at the idling opening position, and if the determination result is positive, the process proceeds to step 66.
If not, the process advances to step 77. The idle switch is included in the throttle sensor 29 mentioned above. Step 6
At step 6, it is determined whether the engine rotational speed Ne; Nc is the minimum engine rotation speed at which fuel cutoff starts, and has a relationship of Nc≧Nh with respect to Nh, which will be described later. In step 67, the flag f=1. The flag f is a flag to indicate that the conditions for implementing a fuel cutoff are satisfied, and once it becomes 1, it is maintained at 1 until the fuel supply is restarted. In step 70, the flag f
/c=1 (6). If flag f/c = 1, a fuel cutoff is implemented. In step 68, it is determined whether f=1 or not. If the determination result is positive, the process proceeds to step 69; otherwise, the process proceeds to step 77. In step 69, the engine rotation speed Ne
'@Nh or not is determined, and if the determination result is positive, the process proceeds to step 70, and if not, the process proceeds to step 74. Nh
and Nl, which will be described later, is the engine rotational speed at which the fuel cutoff is stopped, that is, the fuel supply is restarted, and is Nh)Nl. In step 74, it is determined whether the vehicle speed is v4vo,
If the determination result is positive, the process proceeds to step 76; if not, the process proceeds to step 75. In step 75, it is determined whether or not the braking device, that is, the brake, is in operation. If the determination result is positive, the process proceeds to step 76, and if not, the process proceeds to step 77. In step 76, it is determined whether the engine rotational speed Ne>Nl, and if the determination result is positive, the process proceeds to step 70, and if not, the process proceeds to step 77. In step 70, the flag f=o. In step 78, the flag f/c-0 is set, so the fuel cutoff is canceled, that is, fuel is supplied.

Therefore, if the internal combustion (7) engine is decelerating and the engine rotational speed Ne is Nc or more, fuel cutoff is performed, and if the vehicle speed is more than v'b''-VO or the brake is in operation, the engine rotational speed Ne
When Ne falls to the smaller set value NA, the fuel cut-off is canceled, and in other cases, when the engine speed Ne drops to the larger set value Nh, the fuel cut-off is canceled. In addition, as a preferred embodiment, Nc = 200Or
, p, m,, Nh=1800r, pom,, NA+
=1.000r, plm.

FIG. 4 shows the implementation range and the stop range of fuel cutoff in the present invention. Note that FIG. 4 shows the relationship between the vehicle speed V and the engine rotational speed Ne at the second, third, and fourth speeds. The higher the vehicle speed or engine rotational speed is, the less the vehicle occupant will feel the rolling motion of the vehicle due to the impact caused by fluctuations in the output torque of the engine when the fuel is restored, that is, when the fuel supply is resumed after a fuel cutoff.

This is because as the vehicle speed or engine rotational speed increases, the rolling motion of the vehicle is alleviated due to the large inertia of the vehicle or engine rotating parts (8). Therefore, the fuel can be cut off without any problem in the high-speed region A where ■≧VO and Ne≧Nl and in the high-speed region B where V<VO and Ne≧Nh.

Further, while the braking device is in operation, a braking force acts on the vehicle and the rolling of the vehicle is considerably alleviated. Therefore, in region C where V<VO and Nl <Ne (Nh), fuel cut-off is performed only when the brake system is operating. This region is a region in which fuel cut-off is not performed. Thus, the fuel cut-off region as a whole Expanded.

As described above, according to the present invention, the fuel return engine rotation speed is
As a result of being set in relation to the vehicle speed and the operating state of the braking system, it is possible to maximize the fuel cut-off area while suppressing the shock generated when fuel is restored, significantly improving fuel consumption efficiency and suppressing the release of harmful components. can.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an electronically controlled fuel injection engine to which the present invention is applied, Fig. 2 is a block diagram of the electronic control device of Fig. 1, and Fig. 3 is a flowchart of a program (9) implementing the present invention. , FIG. 4 is a diagram showing areas in which fuel cutoff is performed and stopped. 29...Throttle sensor, 32...Crank angle sensor, 40...Electronic control device patent applicant Toyota Motor Corporation l-2 (10)

Claims (1)

[Claims] In a fuel cutoff method for an internal combustion engine that cuts off fuel supply to the intake system during the deceleration period of the internal combustion engine, the fuel cutoff is stopped when the vehicle speed is above a predetermined value or when the braking device is activated. A method of fuel cutoff for an internal combustion engine, characterized in that the speed is set to a value smaller than it would otherwise be.