JPH0783120A - Controlling method and device for engine air-fuel ratio by stepping motor, etc. - Google Patents

Abstract

PURPOSE:To vary an air-fuel ratio while keeping stability in a lean area and improve speed of responsiveness in a rich area by reading an opening of a bypass valve and judging whether it is the rich area or the lean area from the air-fuel ratio. CONSTITUTION:A control unit 10 reads an opening of a bypass valve 5 by means of a motor controller 11 based on a signal from a stepping motor 8. Stepping speed is cxalculated according to the opening of the bypass valve. The stepping speed is set comparatively slow by means of table in an area where the bypass valve opening is small and an air-fuel ratio is large, that is, a lean area. A step signal is output from the controller 11 to the stepping motor 8. The opening of the bypass valve 5 is steppingly driven while keeping stability for varying the air-fuel ratio. The stepping speed is set comparatively fast by the table in an area where the air-fuel ratio is small, that is, a rich area. The step signal is output to the stepping motor 8 from the controller 11. The opening of the bypass valve 5 is steppingly controlled for improving speed of responsiveness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine air-fuel ratio control method and apparatus using a stepping motor or the like.

[0002]

With respect to such a control method, the present applicant has proposed in Japanese Patent Application No. 5-47075 a method for controlling an air-fuel ratio in a gas engine for driving a generator, for example, in accordance with the number of revolutions varying depending on the engine load. ing.

In the gas engine, for example, the air-fuel ratio is controlled by adjusting the opening degree of a bypass valve provided in the gas bypass passage.

On the other hand, stepping motors and the like are widely used in actuators and the like because they can be driven by digital signals and can obtain an arbitrary step speed (change speed of the bypass valve opening) and are easy to handle. This stepping motor or the like is suitable for adjusting the opening degree of the bypass valve.

[0005]

In controlling the engine rotation fluctuation, the rotation fluctuation amount ΔN is as shown in FIG.
It depends on the air-fuel ratio λ. That is, in the region where the air-fuel ratio λ is large, that is, in the lean region, the rise of the rotation fluctuation amount ΔN is rapid, and it is difficult to stably change the air-fuel ratio.
In the region where λ is small, that is, in the rich region, ΔN is almost constant with almost no influence of the air-fuel ratio λ.

The present invention is based on a stepping motor or the like which enables the air-fuel ratio to be changed while maintaining stability in a region where the air-fuel ratio is large (lean region) and which improves the response speed in the region where the air-fuel ratio is small (rich region). An object is to provide an engine air-fuel ratio control method and apparatus.

[0007]

According to the method of the present invention, when controlling the engine speed fluctuation, the bypass valve opening is read to determine whether the air-fuel ratio is in the rich region or the lean region. The stepping motor or the like is driven at a step speed, and the stepping motor or the like is driven at a high step speed on the rich side.

The device according to the present invention includes a stepping motor or the like for adjusting the opening degree of the bypass valve, a controller for reading the opening degree of the stepping motor or the like and driving the same, and a rich area or a lean area when controlling the rotational fluctuation of the engine. And a control unit including a determination unit for determining whether or not and a calculation unit for calculating the step speed.

[0009]

In the present invention, in controlling the rotation fluctuation,
In a region where the air-fuel ratio has a large influence of one step (lean region), the step speed is slowed down, so the air-fuel ratio can be changed while maintaining stability.

Further, in a region where the air-fuel ratio is small (rich region) where the influence of one step is small, the step speed is increased, so that the response speed can be improved.

[0011]

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

In FIG. 1, an intake passage 1 of a gas engine E for driving a generator L has a gas supply passage 2 for gas G, an air supply passage 3 for air A, and a mixer for mixing gas G and air A. 17, and are connected. The gas supply path 2 is provided with a bypass path 4 that bypasses the mixer 17, and the bypass path 4 is provided with a bypass valve 5 that adjusts the air-fuel ratio. In addition, the intake passage 1 is provided with a throttle valve 6 for adjusting the engine speed.

On the other hand, the output shaft of the gas engine E is provided with a rotary pickup 7 which is a rotational speed detecting means. The rotary pickup 7 is connected to the throttle valve 6 via a throttle controller 6a, and is also connected to a load sensor 9 of the generator L and a control unit 10 as a control means. The stepping motor 8 that drives the bypass valve 5 is connected to the control unit 10.

The control unit 10 is connected to the stepping motor 8, reads the valve opening, and outputs a drive signal to the motor 8, and a motor controller 11, and the air-fuel ratio is leaner or richer than the valve opening. A determination unit 12 that determines whether the area is a region and a calculation unit 13 that determines the step speed are provided.

Next, the control mode will be described.

In FIG. 2, the control unit 10 reads the opening degree of the bypass valve 5 by the motor controller 11 based on the signal from the stepping motor 8 (step S).
1). The read bypass valve opening corresponds to the air-fuel ratio like the relationship between the bypass valve opening X and the air-fuel ratio λ shown in FIG. Therefore, bypass valve opening (= air-fuel ratio λ)
Thus, the calculation unit 13 calculates the step speed based on FIG. 4 (step S3 or S6). That is, in a region where the influence of 1 step S is large, that is, in a region where the bypass valve opening is small and the air-fuel ratio λ is large (lean region), the step speed is set relatively slow by the table. Next, the controller 11 outputs a step signal to the stepping motor 8 to step-drive the opening degree of the bypass valve 5 while maintaining stability to change the air-fuel ratio (step S4 or S7), and when the step drive is completed (step S).
5 or S8), and returns.

On the other hand, in a region where the opening degree of the bypass valve is large, that is, a region where the air-fuel ratio λ is small (rich region), the step speed is set relatively high by the table. here,
In addition to changing the speed in the large and small regions of the air-fuel ratio λ (lean, rich), it is possible to step in the rich side (Table 2) and in the lean side (Table 1) in any region. Changing the speed is more effective.

Then, the controller 11 outputs a step signal to the stepping motor 8 to step drive the opening of the bypass valve 5 to improve the response speed (step S4).
Alternatively, in step S7), when the step driving is completed (step S5 or S8), the process returns.

[0019]

As described above, according to the present invention, the air-fuel ratio can be changed while maintaining stability in the lean region where the air-fuel ratio is large.

Further, the response speed can be improved in the rich region where the air-fuel ratio is small.

Therefore, in the air-fuel ratio control based on the rotation fluctuation, the correct rotation fluctuation amount can be judged and controlled.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a control flowchart.

FIG. 3 is a characteristic diagram of a bypass valve opening versus air-fuel ratio.

FIG. 4 is a step speed calculation table diagram.

FIG. 5 is an air-fuel ratio vs. rotational fluctuation amount characteristic diagram.

[Explanation of symbols]

 A ... Air E ... Gas engine G ... Gas L ... Generator 1 ... Intake passage 2 ... Gas supply passage 3 ... Air supply passage 17 ... Mixer 4 ... Bypass passage 5 ... Bypass valve 6 ... Throttle valve 6a ... Throttle controller 7 ... Rotary pickup 8 ... Stepping motor 9 ... Load sensor 10 ... Control unit 12 ... Motor controller 12 ... Judgment part 13 ... Calculation part

Claims (2)

[Claims] 1. When controlling fluctuation in engine rotation,
The bypass valve opening is read to determine whether the air-fuel ratio is in the rich region or the lean region. In the lean region, the stepping motor, etc. is driven at a slow step speed, and in the rich region, the stepping motor, etc. is driven at a fast step speed. An engine air-fuel ratio control method using a stepping motor or the like. 2. A stepping motor or the like for adjusting a bypass valve opening, a controller for reading and opening the opening of the stepping motor or the like, and a rich area or a lean area for controlling engine rotation fluctuation. An engine air-fuel ratio control apparatus using a stepping motor or the like, which is provided with a control unit including a determination unit for determining and a calculation unit for calculating a step speed.