JPS6043142A - Control method for the time when trouble is caused with differential-pressure sensor used in electronically controlled fuel supplying apparatus - Google Patents

Abstract

PURPOSE:To enable to operate an engine in a stable manner to a certain extent, by controlling the air-fuel ratio by reading out the opening of a throttle valve directly from a map in case that trouble is caused with a differential-pressure sensor. CONSTITUTION:A differential-pressure sensor detects the pressure difference on the opposite sides of a throttle valve, and characteristics relating to the engine speed N, fuel supply rate QF/N per one rotation of an engine and opening theta of the throttle valve are stored in a map of QF/N-N. In case that it is detected that some trouble is caused with the differential-pressure sensor, the air-fuel ratio is controlled by reading out the opening theta of the throttle valve from the map and adjusting the throttle-valve opening by an actuator. By employing such a method, it is enabled to operate an engine in a stable manner to a certain extent even if trouble is caused with the differential-pressure sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION Air-fuel ratio control can be performed by controlling the air flow rate to be supplied to the engine by an actuator operated by a computer based on various information about the engine, including a differential pressure sensor that detects The present invention relates to a control method in the event of a differential pressure sensor failure in an electronically controlled fuel supply system configured as described above.

For example, in the conventional electronic control fuel supply system and 1~,
7-9], a fuel priority type electronically controlled twisting l-1 feeding device is known as disclosed in Publication No. 343. This is explained with reference to FIG. 1, where 10 is an engine and 12 is a throttle. 14 is a throttle valve actuator; 16 is a fuel supply mechanism; 18 is a fuel injection device; 2
0 is an accelerator pedal, 22 is a position sensor for the accelerator pedal 20, 24 is a differential pressure sensor that detects the differential pressure between the upstream and downstream sides of the throttle valve 12, 26 is a rotation sensor that detects the engine speed, and 28 is a computer. The fuel supply system configured in this manner controls the air-fuel ratio by the computer 28 according to various engine conditions including the differential pressure between the upstream and downstream sides of the throttle valve 12 detected by the differential pressure sensor 24. However, if the differential pressure sensor 24 fails, the air-fuel ratio may fluctuate or become very low. However, the engine is controlled very leanly, making driving unstable and, in some cases, causing the engine to stop and making driving impossible.

In view of the following two points, the present invention provides a control method when a differential pressure sensor fails in an electronically controlled fuel supply system, which enables stable driving even when the differential pressure sensor fails. The purpose is to have a computer operate the air flow rate to be supplied to the engine based on various engine information including a differential pressure sensor that detects the differential pressure between the upstream and downstream of the throttle valve. In an electronically controlled fuel supply system configured to perform air-fuel ratio control by controlling an actuator, engine rotation speed (N), - fuel supply amount per rotation (
Characteristics related to QF/N) and throttle valve opening (θ) are stored in the computer as a map of QF/N-N, and if the differential pressure sensor fails,
By detecting this, N and without using the differential pressure sensor output signal. This is achieved by a control method when a differential pressure sensor fails, characterized in that the air-fuel ratio is controlled by directly reading out θ from the F/N based on the above map.

The method of controlling the differential pressure sensor when it fails according to the present invention is described below.
;2. To be clear, the configuration of the electronically controlled fuel supply system itself is the same as the conventional configuration shown in FIG. 1, and all control according to the present invention is processed within the computer 28. The computer 28 has an engine In+! E-turn 1 fl (N), - fuel supply amount per revolution (Q P/N
) and throttle valve opening (θ).
It is stored as an F/N-N map. Next, the control method according to the present invention will be explained with reference to the flowchart shown in FIG. The air-fuel ratio is controlled by the computer based on the following.If a failure of the differential pressure sensor is detected, the fuel supply lQF and engine rotational speed N at this time are detected and the fuel supply amount per revolution QF is determined. /N is calculated, and the throttle valve opening θ is read out from QF/N and N using the above-mentioned map, and air-fuel ratio control is performed by adjusting the throttle valve opening to θ via the actuator. In this case, since θ and air flow rate QA are uniquely determined for IQF/N and N, there will be some error in the air flow rate when the differential pressure sensor is operating normally, but it will be enough. It is possible to run.

As described above, according to the present invention, the structure of the electronically controlled fuel sting supply device remains the same, but by changing the computer software, even if the differential pressure sensor fails,
By detecting this, the computer reads out the throttle valve opening based on a map created by the computer based on the amount of fuel supplied per revolution and the engine speed, and adjusts the throttle valve opening via the actuator. Therefore, stable running is possible even if the differential pressure sensor fails, and since no special equipment is required for this, there is almost no risk of increased costs, making it extremely effective. .

It should be noted that the map stored in the convenience store may be any other map, and in that case, the air-fuel ratio can be controlled based on the information read from the map. Further, in the above description, the fuel priority type electronically controlled fuel supply system has been described, but it goes without saying that the present invention is not limited to this and can be applied to other types of electronically controlled fuel supply systems.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a fuel priority type electronically controlled fuel supply system, and FIG. 2 is a flowchart of a control method according to the present invention. 10 engine, 12 throttle valve, 1/1...
・Actuator, 16 fuel supply unit 'tf&, ],
8. Fuel injection device, 2o... accelerator pedal, 22
Position sensor, 24 ・Differential pressure sensor, 26 Rotation sensor")--+28... Computer.

Claims (1)

[Claims] The air flow rate to be supplied to the engine is controlled by an actuator operated by a computer based on various engine information including a differential pressure sensor that detects the differential pressure between the upstream and downstream sides of the throttle valve. In an electronically controlled fuel supply system configured to perform air-fuel ratio control, engine rotation speed (N), - fuel supply per rotation W - (Q
Characteristics related to F/N) and throttle valve opening (θ) are stored in the computer as a map of QF/N-N, and if the differential pressure sensor fails, by detecting this, the differential pressure sensor output signal θ directly from N・ and QF/N based on the above map without using
1. A method of controlling differential pressure sensor 1 when a failure occurs, characterized in that air/fuel efficiency control is performed by reading out the following information.