JPS624677Y2 - - 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. A means for detecting the opening of each throttle valve provided, a means for detecting the strength of the engine knock phenomenon, a means for storing the possible relationship between the opening of the throttle valve and the gas amount adjustment valve, and 0 when starting the engine.
In addition to providing a storage means for a variable A set to
The degree of opening of the throttle valve is detected as appropriate, and when the value is above a certain level, the strength of the engine knock phenomenon is detected, and the gas amount adjusting valve is adjusted so that the value becomes a small value within a certain range. The opening/closing value of the throttle valve is adjusted, and the difference between the detected opening value of the gas amount adjustment valve at that time and the valve opening value seen from the numerical table is stored in variable A, and if the detected opening value of the throttle valve is other than the above In the area, the opening degree of the gas volume adjustment valve is adjusted so that the difference between the opening value of the gas volume adjustment valve obtained by adding the above variable A according to the numerical table 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 amount.

An embodiment 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 in an embodiment of the present invention. 22 is first mechanically connected to the electric motor 12 by a lever 14, and then reaches the mixer 15 via the driven gas amount regulating 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 as shown in block 1 can have similar functions. 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.

In FIG. 1, reference numeral 27 indicates a sensor that detects the knock strength of combustion in the engine 20. A known vibration displacement detector or the like can be applied to this sensor 27, and the sensor 27 detects the knock strength of the combustion of the engine 20. It is to be installed in a suitable place.

The single output of the sensor 27 is output as an analog waveform as shown in FIG. 4-A, and the strength of the knock phenomenon is expressed as an increase or decrease in the height of the waveform and the number of waves.

Moreover, the periodic appearance of the waves is due to the periodic combustion process during the engine cycle.

Now, in order to read this output with a microcomputer system, a process using the signal preprocessing circuit 26 is necessary, and one of the methods is as follows.
The original waveform can be processed by a peak hold circuit that is triggered and reset at appropriate timings synchronized with the engine cycle.

In this case, the output of the signal preprocessing circuit 26 is
It will look like figure B, and in the section in the figure, A/
It can be read by D conversion.

Therefore, in this case, what is indicated by 25 in FIG.
It becomes an A/D converter.

Another preprocessing method is to use the signal preprocessing circuit 26 as a comparator circuit with an appropriate slice level, but in this case, the output is a pulse output as shown in Figure 4-C.
If the A/D converter 25 in Fig. 1 is a pulse counter that is started and reset in synchronization with the engine cycle, the microcomputer system can determine the counted value as a substitute value for the strength of the knock phenomenon. It is.

To explain the operation of the control device of the present invention based on the above configuration, first, the opening degree of the throttle valve 16 is adjusted to suit a gas fuel engine for a generator set, etc., which is operated at a constant speed, which is the premise of the present invention. can be used as a substitute characteristic value for the load factor.

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 order to avoid the misfire region or knocking region in a gas fuel engine, it is necessary to adjust the air-fuel ratio to a predetermined value, and that value varies depending on the load factor, as shown in Figure 2 above. is a graph of the situation, and in addition to the above avoidance area, fuel consumption,
Considering the level of exhaust gas, it is possible to set one possible control line 31.

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.

According to experimental results, when the fuel gas components change or when the engine 20 changes over time, the misfire region and knocking region shown in FIG. 2 change in a substantially vertically shifted manner.

However, in the present invention, even if such a situation occurs, the numerical table is automatically shifted up or down according to the sequence described below, so that the new engine 20,
It is sufficient to create and memorize a numerical table based on typical gas component calorific values, which is one of the important features of the present invention.

Next, although the control logic is as shown in the flowchart of FIG. 3, the points to be noted here will be explained first. As is clear from Figure 2, in gas engines, the operable range is narrow in the high load range, and this operable range changes sensitively to changes in the fuel gas calorific value, but generally the calorific value is When the temperature rises, the gas amount adjustment valve 1 starts to knock.
The opening value of 1 is decreasing.

Therefore, this can be determined by detecting the strength of the knock, and an output is made to reduce the opening of the gas amount regulating valve 11, but if it is reduced too much, it will enter the misfire range.

The present invention solves this problem by controlling it to a point where a slight knock phenomenon is always observed.

In addition, in the low load area, the optimal gas flow adjustment valve 1 confirmed in the high load area by the above sequence
By storing the difference between the opening degree of 1 and the numerical table value as variable A, and always shifting the numerical table value by that amount and setting it as the target value, optimal operation is possible.

In addition, with the means constituting the present invention, if the engine 20 is always operated only in the low load range, such correction will not be performed, but as is clear from Fig. 2, in the low load range Since the operable range is wide, phenomena such as misfires and knocks are less likely to occur.

On the other hand, each target value to be compared with the detected value should be determined with a certain allowance α in order to prevent chattering.

In addition, in consideration of the rotational angular velocity of the electric motor 12, the interval should be selected to be a time length that does not cause much control overshoot, and the interval can be generated by using an external clock or by using software. It is conceivable to adopt a method using a wear timer.

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 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 achievable.

In addition, in the present invention, mixer 1 is used as a control output.
Although the opening degree of the gas amount regulating valve 11 in the previous stage of 5 was controlled,
On the other hand, it goes without saying that similar control can be achieved even if the gas amount adjustment valve 11 is provided on the air 23 line side in Figure 1, and in this case, the numerical table pattern in Figure 2 is appropriate. becomes.

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 memorized in the form of a numerical table, so any pattern can be adopted, and as a result, the misfire region and knock region Optimum patterns that have been tested and confirmed during engine development can be freely set, such as avoiding fuel consumption and minimizing fuel consumption.

In general, gas-fueled engines often use gases with variable calorific values, such as municipal waste processing gas, as fuel, and in this case, the optimal air-fuel ratio pattern that should be set above changes depending on the gas calorific value. In this respect, if the present invention is adopted, the stored numerical table will be automatically updated and changed by providing a knock phenomenon detector.

Therefore, if the control device of the present invention is adopted, effects such as long-term unmanned operation will be achieved.

On the other hand, gas fuel engines have the disadvantage that the above-mentioned notch range changes little by little due to changes over time. This enables long-term maintenance-free operation.

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 you don't have to worry about it.

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 a fast response and has 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 it is capable of controlling the air-fuel ratio in any pattern, and is capable of changing fuel gas components. Even if the engine characteristics change over time, the knock range and misfire range are automatically avoided, making it possible to control the engine more reliably and greatly contributing to fuel efficiency reduction and exhaust gas countermeasures.

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. 3 is a flowchart of the control device of the gas fuel engine shown in FIG. 1, FIG.
The figure shows a waveform representing the output of the signal pre-processing circuit in Fig. 1, and Fig. 4-C shows the pulse output when the signal pre-processing circuit in Fig. 1 is replaced with a comparator circuit having an appropriate slice level. It shows the waveform. 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, 25... A/D converter, 26... Signal preprocessing circuit, 27... Sensor.

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 of a throttle valve, a means for detecting the opening of each of the gas amount adjusting valve provided in the front stage of the mixer and the throttle valve provided in the rear stage of the mixer, and the engine A means for detecting the strength of the knock phenomenon, a means for storing the possible relationship between the opening degree of the throttle valve and the gas amount adjusting valve, and a means for storing a variable A which is set to 0 when the engine is started are provided. , the opening degree of the throttle valve is appropriately detected, and when the opening degree is above a certain level, the strength of the engine knock phenomenon is detected, and the opening degree of the gas amount adjusting valve is adjusted so that the opening degree of the throttle valve becomes a small value within a certain range. Adjust opening/closing, and store the difference between the detected opening value of the gas volume adjustment valve at that time and the valve opening value seen from the numerical table in variable A, and also if the detected opening value of the throttle valve is other than the above. In the region of , the opening of the gas amount adjusting valve is adjusted so that the difference between the opening value of the gas amount adjusting valve added with the above variable A according to the numerical table and the detected opening value of the gas amount adjusting valve is reduced. 1. A control device for a gas fuel engine, characterized in that it is provided with arithmetic control and output means that can increase or decrease the temperature.