JPS624674Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a gas fuel engine that automatically adjusts the air-fuel ratio or excess air ratio of the gas fuel engine.

In gas fuel engines, especially electrically ignited gas fuel engines, it is essential to optimize the air-fuel ratio as a means to avoid knock and misfire regions and to improve fuel consumption and exhaust gas characteristics. It is.

Conventional techniques related to such adjustment devices generally do not include a control device, but use mechanical means such as providing a fuel throttle section that is linked to a butterfly that senses the dynamic pressure caused by the air flow in the mixer section.

On the other hand, the air-fuel ratio, which avoids the knocking and misfire range and also takes into account the minimum fuel consumption and exhaust gas, generally does not have a simple linear relationship with the load factor, and the vertical axis in Figure 2 shows the gas amount. The pressure regulating valve opening and the throttle valve opening are expressed on the horizontal axis as a knocking region, a misfire region or stall region, and a fuel efficiency deterioration region.

However, since the above-mentioned conventional technology uses mechanical means, this objective cannot be achieved and adjustment is also difficult.

In addition, as another general conventional technology, there is a method such as installing an oxygen concentration sensor at the outlet of the combustion chamber and adjusting the amount of fuel supplied based on the detection result, but the oxygen concentration sensor used here They are expensive and have a durability of only a few hundred hours, and they also have many disadvantages such as the fact that their output changes significantly depending on the temperature during use, and they require high control circuit costs and frequent replacement. There was a problem that the cost burden was large.

Therefore, the present invention was made to solve the problems of the conventional technology, and provides a gas fuel engine with a control device that avoids the knock region and misfire region and improves the fuel consumption rate and exhaust gas characteristics. It is intended to.

That is, the control device for a gas fuel engine of the present invention is applicable to a gas fuel engine having a governor mechanism that maintains a constant speed by increasing or decreasing the opening degree of a throttle valve. It has means for detecting the opening of each throttle valve provided in the throttle valve, and a means for memorizing the possible relationship between the opening of the throttle valve and the gas amount adjusting valve in the form of a numerical table. Detect the opening degree of the gas volume adjustment valve, select the possible opening degree of the gas volume adjustment valve based on the above numerical table, and adjust the gas volume so that the difference between this value and the detected opening value of the gas volume adjustment valve is reduced. It is constructed by providing arithmetic control and output means that can increase or decrease the opening degree of the valve.

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

First, FIG. 1 is a conceptual system diagram showing a gas fuel engine according to an embodiment of the present invention. Fuel gas 22 supplied to the combustion chamber of the engine 20 is first mechanically connected to an electric motor 12 by a lever 14. The gas then reaches the mixer 15 via the driven gas amount adjustment valve 11 . Further, air 23 is taken into this mixer 15 from another port, mixed, and then passed through a throttle valve 16 to reach the combustion chamber of the engine 20.

Here, in the present invention, as a prerequisite technology, it is assumed that the throttle valve 16 is controlled by the governor mechanism 18 and is adjusted to a valve opening degree that can always maintain the rotational speed of the engine 20 constant. Although this governor mechanism 18 is outside the scope of the present invention, any method may be used, such as applying an electronic governor that operates in response to a signal from the engine rotational speed detector 21 to the governor mechanism 18.

Next, 13 is an opening detector for the gas amount adjustment valve 11, and 17 is an opening detector for the throttle valve 16, both of which can be provided with known technology such as a potentiometer. can.

The opening degree of the throttle valve 16 and the gas amount adjustment valve 11
As shown in this embodiment, a microcomputer system can be used as the means for storing the possible relationship between the two in the form of a numerical table and the arithmetic control means.

That is, 2 in Figure 1 is the CPU, 3 is the ROM,
Here, a calculation control program and possible values of the gas amount regulating valve 11 can be stored in the form of a numerical table. 4 is a RAM, and 5 is an I/O interface.

It should be noted that each unit shown in 2 to 5 above can not only be constructed from a discrete LSI, but also a one-chip microcomputer like block 1 can have the same function. Further, 8 indicates a so-called system bus line consisting of a data bus, an address bus, and a control bus.

Furthermore, since the values detected by the two opening degree detectors 13 and 17 are detected as analog values, a multiplexer and an A/D converter 6 are required, which can also be connected to the system bus line 8. .

In addition, the calculation result is the I/O interface 5
When the electric motor 12 is used, the output is output as an opening increase/decrease signal of the electric gas amount adjustment valve 11, and the output is the forward and reverse rotation signals 10,
It is output as 9, which is a power transistor,
Alternatively, connection can be made via an amplifier 7 using a relay or the like.

The operation of the control system of the present invention based on the above configuration will now be explained. First, the opening of the throttle valve 16 can be used as a substitute characteristic value for the load factor in a gas fuel engine for a generator set or the like that is operated at a constant speed as assumed by the present invention.

Further, the opening degree of the gas amount regulating valve 11 can be used as a substitute characteristic value indicating the magnitude of the air-fuel ratio.

In a gas fuel engine, in order to avoid the misfire region or knocking region, it is necessary to adjust the air-fuel ratio to a predetermined value, and that value varies depending on the load factor, and the above-mentioned second The figure is a graph of the situation, and it can be set as one possible control line 31, taking into consideration fuel consumption and exhaust gas level in addition to the above-mentioned avoidance range.

One of the features of the present invention is to memorize this control line 31, and the reason why the control line 31 is step-shaped is for quantization when converting into a numerical table. Needless to say, the larger the storage capacity is, the more fine-grained control lines 31 can be stored.

Next, the control logic is as shown in the flowchart of Fig. 3, but it should be noted here that the detected value of the opening degree of the gas amount adjustment valve 11 is compared with the target value according to the numerical table. In this case, it is effective to provide a certain allowance balance to prevent chattering.

In addition, the interval must be selected at an optimal value that does not cause frequent control overshoots in consideration of the rotational angular velocity of the electric motor 12, and the interval itself must be set using a software timer or an external clock. It is possible to adopt this method.

Furthermore, to illustrate some other embodiments other than the embodiments of the present invention that are applicable to the present invention, the electric motor 12 in FIG.
For example, it is possible to use a servo solenoid,
In this case, the output from the control circuit is an analog value, so this is achieved by assigning the number of bits corresponding to a predetermined precision to the output section of the I/O interface 5 and outputting it via a D/A converter (not shown). It is possible.

In addition, in the present invention, mixer 1 is used as a control output.
Although the opening degree of the gas amount adjusting valve 11 at the front stage of FIG. In this case, the numerical table pattern shown in FIG. 2 would be appropriate.

Furthermore, it goes without saying that a similar sequence circuit can be constructed using ordinary random logic without using the CPU 2 as a control circuit.

Note that when the opening degree of the gas amount regulating valve 11 is changed by the control device of the present invention, it may cause a change in the rotational speed of the engine 20, but this can be immediately corrected by a separately provided governor mechanism. It is.

Therefore, if the control device of the present invention is applied to a gas fuel engine, the optimal air-fuel ratio pattern for the load factor is stored in the form of a numerical table, so any pattern can be adopted, and as a result, the pre-fire range and the You can freely set optimal patterns that have been tested and confirmed during engine development, such as avoiding areas and minimizing fuel consumption.

In addition, since the opening of the throttle valve is detected as a substitute characteristic for the load factor, the device is inexpensive, and unlike load detection methods such as torque sensors, the installation location is restricted depending on the type of load. The advantage is that there is no need to worry about

Furthermore, since the control device of the present invention does not measure the air-fuel ratio itself, there is no need for an expensive and difficult-to-handle sensor such as an oxygen concentration sensor. Because it uses a numerical table storage system, it has quick response and fewer problems such as hunting.

As described above, the control device of the present invention has a simple mechanism, is low in price, and is easy to adjust and maintain, yet can control the air-fuel ratio in any pattern, By avoiding
This enables more reliable engine control and minimizes fuel consumption, exhaust gas, etc.

Note that the present invention can be effectively applied to gas fuel engines in general that operate at a constant speed.

[Brief explanation of the drawing]

Fig. 1 is a conceptual system diagram showing a gas fuel engine in an embodiment of the present invention, and Fig. 2 is a control of the gas fuel engine shown in Fig. 1 in relation to the gas amount adjustment valve opening and throttle valve opening of the gas fuel engine. FIG. 3 is a flowchart of the control device for the gas fuel engine shown in FIG. 1. 1...Block, 2...CPU, 3...ROM,
4...RAM, 5...I/O interface,
6...Multiplexer, A/D converter, 7
...Amplifier, 11...Gas amount adjustment valve, 13...Opening degree detector, 15...Mixer, 16...Throttle valve, 17...Opening degree detector, 18...Governor mechanism, 20...Engine, 21... Engine rotation speed detector, 31... Control line.

Claims (1)

[Scope of utility model registration request] In a gas fuel engine having a governor mechanism that maintains a constant speed by increasing or decreasing the opening degree of a throttle valve, a gas amount adjusting valve provided upstream of a mixer and an opening detection means for each of the throttle valves provided downstream of the mixer; It has a means capable of memorizing the possible relationship between the opening degree of the throttle valve and the gas amount adjusting valve in the form of a numerical table, and also detects the opening degree of the throttle valve as appropriate, Arithmetic control and output means capable of selecting the opening degree of the gas volume adjustment valve that should be changed, and increasing or decreasing the opening degree of the gas volume adjustment valve so as to reduce the difference between this value and the detected opening value of the gas volume adjustment valve. A control device for a gas fuel engine, characterized in that it is provided with: