JPS58214655A - Controller for gas fuel engine - Google Patents

Abstract

PURPOSE:To keep air-fuel ratio to an optimum value in the whole operation state by reading-out an optimum gas feeding quantity in accordance with the eng ine revolution speed and the opening degree of a throttle from a memory and keeping the gas feeding quantity to the value read-out by using a control means. CONSTITUTION:The output of a revolution-speed detector 2 installed onto an engine 1 is inputted, together with the value on a counter 15, into a governor 8 and the engine revolution speed is kept at a prescribed value through a throttle valve 14. While, the output of a throttle valve opening degree detector 14 is inputted into a microcomputer 5 through an A/D converter 16, and an optimum gas feeding quantity is read-out from a ROM4, on the basis of the revolution speed value on the counter 15 and the value of the throttle opening degree. Said microcomputer 5 controls opening and closing of a solenoid valve 35 through a pulse width conversion circuit 25 and an amplifying circuit 28, on the basis of the read-out value, and thus the opening degree of a gas feeding control valve 43 is controlled.

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 according to the operating condition 11 of the engine.

In general, the fuel efficiency and exhaust gas of a gas fuel engine are largely influenced by the air-fuel ratio, as can be seen from the operating characteristic diagram, an example of which is shown in FIG. Therefore, in order to reduce fuel consumption and reduce harmful components in the exhaust gas (vJ*), in order to operate the engine well, the optimum air-fuel ratio must always be obtained depending on the operating conditions, that is, the engine speed and load condition. Conventional technologies for performing such control include one that uses intake air pressure to correct the air volume, and one that uses variable control that is linked to a butterfly that senses the dynamic pressure caused by the air flow in a part of the mixer. It is not common to use mechanical means such as setting up a throttle mechanism to adjust the fuel supply amount, and it also changes depending on the rotational speed. It is difficult to always obtain the optimal air-fuel ratio,
Furthermore, variable throttle mechanisms are expensive and relatively large, making them unsuitable for small engines.

Another conventional technique is to install an oxygen coal-making sensor at the outlet of the combustion chamber and adjust the fuel supply amount based on the detection results, but the oxygen concentration sensor is generally expensive. Moreover, they have problems such as poor durability, unstable operation, complicated control circuits, and high replacement costs.

The present invention has focused on these points, and has been made for the purpose of providing a control device for a gas fuel engine that can appropriately control the air-fuel ratio according to the operating state. means for detecting, means for detecting the throttle opening of the engine, means for storing the possible relationship between the three elements of rotational speed, throttle opening, and gas co-supply amount in the form of a numerical table; and sampled rotational speed. and a calculation means for determining the gas supply amount based on the numerical table and outputting a control output according to each detection result of the throttle opening degree, and an adjustment means for adjusting the gas supply amount based on the control output of the calculation means. It is characterized by

That is, the present invention indirectly detects the air amount using the engine rotational speed and throttle opening, and also detects the load factor using the throttle opening, which is a substitute characteristic thereof, and calculates the load and air amount based on these detection results. The system calculates and controls the gas supply amount according to the rotational speed and throttle opening using arithmetic means.The optimum gas supply amount for changes in the two elements of rotational speed and throttle opening is determined in advance through experiments, and this is calculated using the numerical table. By memorizing the air-fuel ratio in the form, you can always obtain the air-fuel ratio suitable for the operating conditions at that time. The numerical table to be stored is a three-dimensional numerical table in which the three elements of rotational speed, throttle opening, and gas supply amount are orthogonal to each other, as illustrated in FIG.

Next, embodiments of the present invention will be described with reference to the drawings.

3 to 7 show a first embodiment in which the valve opening degree of the gas pressure regulator is controlled by adjusting the reference pressure of the gas pressure regulator. The vJ3 diagram is a conceptual system diagram, and in the figure, f1+ is the engine, (2) #'i' is the rotation speed detector which is a means of detecting the rotation speed, and (3) is the throttle opening which is the means to detect the throttle opening. (4) is a ROM which is a storage means, (5) is a microcomputer which is a calculation means, (6) and (7) are a gas pressure regulator and a negative pressure control electromagnetic device which are means for adjusting the gas supply amount. It is a valve.

The fuel gas (river) supplied to the combustion chamber of the engine +1) passes through the gas pressure regulator (6) to the mixer (12), where it is mixed with air (13) taken in from another boat.
It is supplied to the engine (1) via the throttle valve (14), and the operating state of the engine (1) is detected based on the rotational speed and throttle opening. As the rotational speed detector (2), for example, one that outputs a pulse output proportional to the rotational speed can be used, and the output is sent to the detector θ and converted. Also, the opening degree detector (3) of the throttle valve (+4)
) can be, for example, a potentiometer, the output of which is sent to a multiplexer A/D converter θ6) and converted into a digital quantity.

Microcomputer (5) (2]) HCPU %
422 is Oboro, (Ten)) is ■10 interface, (
The system path line consists of a data bus, an address bus, and a control bus stop. Each unit constituting the microcomputer (5) may be composed of discrete LSIs, or a so-called one-chip microchip that integrates the entire system may be used.

The ROM+41 stores arithmetic control programs and data that represents the possible relationship between the three elements of rotation speed, throttle opening, and gas supply amount; however, in this example, the gas supply amount is not controlled. It is converted into data in the form of negative pressure.

The calculation result is sent from the 10 interface (c) to the pulse width conversion circuit (e) and output as a solenoid pulp opening/closing signal (a). Figure 4 shows the waveform of this solenoid pulp opening/closing signal.As will be described later, the ratio of pulse width t to period T (t/T x
1oo%), the negative pressure control solenoid valve (7) is controlled. (2η is the amplifier circuit, (company) is the reference pulse generator, (c) is the reference pulse signal, and the solenoid pulp opening/closing signal (company) is sent to the negative pressure control solenoid valve (7) via the amplifier circuit Qn. .

The gas supply amount is adjusted by applying a controlled pressure to the -E section of the diaphragm of the gas pressure regulator (6) and controlling the valve opening.

The negative pressure control solenoid valve (7) consists of a negative pressure chamber with a diaphragm type constant pressure valve (button) and a solenoid pulp (33). 04), and also the solenoid pulp (
33) to the atmosphere, and a gas pressure regulator (
The diaphragm of 6)← also communicates with the back of 1). The negative pressure at the throttle valve inlet that acts on this negative pressure V cia K changes depending on the operating condition, but when the negative pressure exceeds a certain value by connecting the spring +341, the constant pressure valve assembly closes and the negative pressure chamber becomes 0 odor. It is designed to maintain a constant pressure. If the solenoid pulp 03) is off, a constant negative pressure is applied to the diaphragm kl) of the gas pressure regulator (6), and the solenoid pulp (83)
When the valve is repeatedly turned on at a certain rate, the negative pressure decreases according to the valve opening time rate. The aforementioned solenoid pulp opening/closing signal (
100% of t/T

On the other hand, in the gas pressure regulator (6), the regulating valve (43) opens and closes in response to the biasing force of a spring applied to the diaphragm (41) and the control negative pressure given from the negative pressure control solenoid valve (7). The pressure is adjusted to a predetermined pressure, and the relationship between the controlled negative pressure and the opening degree of the regulating valve is a linear relationship as shown in FIG.

Therefore, if the opening time ratio of the negative pressure control solenoid valve (7) is determined, the valve opening degree of the gas pressure regulator (6) will remain fixed.
Since the gas supply pressure is adjusted to a predetermined pressure, the amount of gas supplied is thereby controlled and an optimum air-fuel ratio can be obtained.

In addition, the negative pressure supplied to the negative pressure chamber of the negative pressure control solenoid valve (7) may be extracted from the air inlet of the mixer (12) instead of the inlet of the throttle valve (+4). .

In the figure, (8) is the governor mechanism, and the rotation speed detector (2) is the governor mechanism.
) is configured to adjust the valve opening degree of the throttle valve 04) in accordance with the detection output of the engine (1) to maintain the rotational speed of the engine (1) constant. In other words, in this embodiment, there is little need to use the rotational speed as one of the elements for control in a steady state, and a great effect is expected in cases such as a sudden change in load or a decrease in rotational speed due to overload. However, it goes without saying that the present invention can be applied not only to such constant-speed operating engines but also to variable-speed engines, and the features of the present invention are more fully exhibited in the case of variable-speed engines. The figure shows a control flowchart for the series of operations described above.

Next, a second embodiment will be described with reference to FIGS. 8 and 9. In this embodiment, the opening degree of the regulating valve of the gas pressure regulator is directly adjusted by a regulating valve driving mechanism, and here a motor with a linear head is used as the regulating valve driving mechanism.

Hereinafter, points different from the first embodiment will be described.

In Figure 8, the mouse is an 11-movement motor (the image is a linear head, the decoy is a displacement detector), the microcomputer (5
) increase signal (26a) or decrease signal @ (26b)
The electric motor (motor) rotates forward or reverse depending on the direction of rotation, lowering or raising the linear head [υ]. By raising and lowering the linear head ←, the set value by the spring ←2 changes, the opening degree of the regulating valve ← is adjusted, the gas supply pressure is adjusted to a predetermined pressure, and the gas supply amount is controlled.

As mentioned above, in this embodiment, the gas supply amount is controlled by the position of the linear head, so the gas co-supply amount stored in the numerical table is converted into data in the form of the displacement amount of the linear head. The amount of displacement of the linear head is detected by a displacement detector, and a multiplexer A/D converter (1
(Feedback is sent to the microcomputer (6) via C, and control is performed by comparing the detected displacement amount with the set value of the i table. FIG. 9 shows a control 70 chart of this embodiment. It is.

In all of the above embodiments, the gas supply amount is controlled by adjusting the gas supply pressure.
The gas supply amount #-t@1 can also be controlled by a gas amount adjustment valve as in the third embodiment shown in FIGS. 10 and 11.

In the figure, (9) is the gas amount adjustment valve, and the increase signal (
When the electric motor (44I) is driven according to the wave signal (26a) or the wave signal (26b), the opening degree of the internal regulating valve (not shown) is adjusted via the link (4), and the flow rate of the fuel gas is adjusted. The opening degree of the regulating valve is detected by an opening degree detector I47) and fed back to the microcomputer (6), where it is compared with a government value and controlled. Therefore, in this embodiment, the gas supply amount stored in the numerical table is converted into data in the form of the opening degree of the gas amount adjustment valve (9).
The figure shows a control flowchart of this embodiment.

Generally, a gas mixer is used to control the mixing ratio of air and fuel gas to mix them at an appropriate ratio, but as in the present invention, the gas supply amount is controlled by a gas pressure regulator or a gas volume adjustment valve. When controlling a mixer, there is almost no need to use a complicated and expensive mixer, and this can be omitted. Therefore, in the third embodiment, the mixer is not used, and the fuel gas (11) and air 03) discharged from the gas amount adjustment valve (9) are directly supplied to the throttle valve (I4). ) is simply provided with a gas supply valve←9) on the inlet side. φ0) is an air filter.

The omission of such a gas mixer can also be done in the first and second embodiments, and the fuel gas (1) discharged from the gas pressure regulator (6) is connected to the throttle valve as in the embodiment shown in FIG. 04). In this case, the memorized numerical table and control chart 70 may be the same as those described in the first and second embodiments, and the part of the mixer 02) in FIGS. 3 and 8 may be replaced with that in FIG. Since the gas supply valve (49) and air filter (50) shown may be replaced, specific drawings are omitted.

As is clear from the description of each of the embodiments above, the present invention stores the desirable relationship between the three elements of engine rotation speed, throttle opening, and gas supply amount in the form of a numerical table, and Since the amount of gas supplied M is controlled according to the throttle opening, by storing the optimum pattern confirmed through tests during engine development, the excess air ratio can be set to 1.
By setting the value between 1 and 1.3, economical operation can be carried out at all times, and the generation of harmful exhaust components can be suppressed. Furthermore, by setting the excess air ratio to 1.0 during overload, for example, it is possible to easily perform control to prevent the rotational speed from decreasing.

Furthermore, in the present invention, since the opening degree of the throttle valve is detected as a substitute characteristic for the load factor, there is no need to use an expensive device such as a torque sensor that has many restrictions on use, and the air-fuel ratio itself is not measured. Therefore, there is no need for expensive and troublesome items such as oxygen concentration sensors.
There is also the advantage of being able to obtain a control device that is inexpensive and has excellent responsiveness.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the operating characteristics of the gas fuel engine according to the present invention with respect to the air-fuel ratio, and FIG. 2 is a diagram showing an example of a numerical table according to the present invention. Figures 3 to 7 show the first embodiment of the present invention. Figure 3 is a conceptual system diagram, Figure 4 is a waveform diagram of the solenoid opening/closing signal, and Figure 5 is a negative pressure control A characteristic diagram showing the relationship between the valve opening time ratio of the solenoid valve and the controlled negative pressure, Figure 6 is a characteristic diagram showing the relationship between the controlled negative pressure and the valve opening degree of the gas pressure regulator, and Figure 7 is a control flow chart. Fig. 8 and Fig. 9 show the second embodiment, Fig. 8 is a conceptual system diagram, and Fig. 4!59 is a control flow chart. By way of example,
FIG. 10 is a conceptual system diagram, and FIG. 11 is a control flowchart. (+) #-j engine, (2) is rotation speed detector, (3) is throttle valve opening detector, (4) is ROM, (f
il is a microcomputer, (6) is a gas pressure regulator,
(7) is a negative pressure control solenoid valve, (9) is a gas amount adjustment valve, (kawa is fuel gas, haze is air, (b) is a solenoid pulp opening/closing signal, (26a) is an increase signal, (26b) is a wave Signal, reconnaissance twJ motor, ← is the linear head, ← is the 81ti displacement detector, ← is the opening detector of the gas amount adjustment valve. Patent applicant Yanmar Diesel Co., Ltd. agent
Person Patent Attorney Shino 1) Jichi Tokukai Sho 58-214655 (5)

Claims (1)

[Claims] ft) means for detecting the rotational speed of the engine, means for detecting the throttle opening of the engine, and means for storing the possible relationships among the three elements of rotational speed, throttle opening, and gas supply amount in the form of a numerical table. and a calculation means for determining the gas supply amount based on the above-mentioned numerical table according to each detection result of the sampled rotational speed and throttle opening and outputting a control output, and adjusting the gas supply amount based on the control output of the calculation means. A control device for a gas fuel engine, characterized in that it is equipped with an adjusting means for adjusting the amount.