JP3952753B2 - Fuel supply device for lean burn gas engine and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a fuel gas supply line provided with a gas governor, an air supply line provided with an upstream air cleaner, and a carburetor for mixing supply gas from the fuel supply line and supply air from the air supply line. Further, the present invention relates to a fuel supply device and a control method for a lean combustion type gas engine configured by a balance pipe that communicates an inlet pressure of the carburetor with a loading pressure communication port of the gas governor.
[0002]
[Prior art]
As shown in FIG. 7, in the gas engine E, when the air cleaner 2 interposed in the air supply line AL is clogged and the ventilation resistance increases, the air supply is maintained in order to keep the air-fuel ratio constant. The inlet pressure of the carburetor 3 interposed in the line AL (the air cleaner ventilation resistance and the negative pressure generated by the carburetor venturi) is used as a loading pressure, and the communication port 1a of the gas governor 1 interposed in the fuel gas supply line FL. The gas governor 1 reduces the supply gas pressure flowing through the fuel gas supply line FL in conjunction with the balance pipe BP.
[0003]
That is, the air cleaner ventilation resistance and the negative pressure generated in the venturi of the carburetor 3 are transmitted to the gas governor 1 as a loading pressure. The gas governor 1 refers to the loading pressure, and the supplied fuel gas is substantially equal to the loading pressure. The pressure (secondary pressure) is adjusted and supplied to the carburetor 3.
In FIG. 7, reference numeral 9 denotes an intake pipe, and reference numeral 10 denotes a throttle valve interposed in the intake pipe 9.
[0004]
Here, the air-fuel ratio of the gas engine is preferably constant regardless of the operating conditions. However, in the fuel supply device of the lean combustion gas engine, as shown in FIG. The supply fuel gas pressure is also approximately equal to the loading pressure, and the supply fuel gas pressure is low at high loads.On the other hand, if the air / fuel ratio is set to be appropriate at high loads, it becomes rich at low loads. The problem of becoming.
[0005]
Therefore, as a method for optimizing the air-fuel ratio, a fuel adjustment valve is provided on the fuel supply side to the carburetor, or an air bypass valve is provided on the intake air side, and the fuel adjustment is performed based on information from the 02 sensor provided in the exhaust system. A device for adjusting and controlling the fuel flow rate by controlling a valve, or a device for adjusting and controlling the flow rate of intake air by controlling the air bypass valve is known.
[0006]
However, since the fuel adjustment valve and the device that drives the fuel adjustment valve handle flammable gas, general-purpose products cannot be used, and are expensive from the viewpoint of safety (supporting seals and electrical explosion-proofing). Cost).
[0007]
[Problems to be solved by the invention]
The present invention has been proposed in view of the above-mentioned problems of the prior art, and even if there is a load or other conditions (for example, rapid fluctuations in the clogging of the air cleaner), the air-fuel ratio can be reduced at an appropriate level. An object of the present invention is to provide a fuel supply device for a lean combustion gas engine and a control method therefor.
[0008]
[Means for Solving the Problems]
According to the present invention, a fuel gas supply line having a gas governor interposed therein, an air supply line having an air cleaner interposed upstream, a supply gas from the fuel gas supply line, and a supply air from the air supply line are mixed. And a balance pipe that communicates the inlet pressure of the carburetor to the loading pressure communication port of the gas governor. A variable atmospheric release valve, an intake pressure detecting means interposed between the air cleaner and the carburetor of the air supply line, and a gas pressure interposed between the gas governor and the carburetor of the fuel gas supply line A detection means and a load detection means provided on the output side of the gas engine, and an intake pressure from the intake pressure detection means. Based on the pressure signal, the gas pressure signal from the gas pressure detecting means, the load signal from the load detecting means, and the gas pressure map indicating the relationship between the set load and the supply gas pressure, Control means for driving and controlling to the target gas pressure is provided.
[0009]
In the fuel supply system for the lean combustion gas engine (E), the engine rotation detecting means (11) is provided, and the opening ratio is variable based on the fluctuation information of the engine rotation detected by the engine rotation detecting means (11). You may return a gas engine to the original rotational speed by changing the air release rate of the air release valve (4).
[0010]
The open rate variable atmospheric release valve (4) is preferably a duty solenoid valve, for example, and the atmospheric release rate in the case of a duty solenoid valve indicates a duty ratio.
[0011]
According to the fuel supply device for a lean combustion gas engine of the present invention having such a configuration, the open rate variable atmospheric release valve (for example, the duty solenoid valve 4) uses the intake pressure as the loading pressure of the gas governor (1). Since it is an intermediary and does not communicate the fuel gas itself, the cost of handling explosion-proof measures and seals is minimal.
In addition, since the open rate variable atmospheric release valve can be a general-purpose product, the entire system is simple and inexpensive.
[0012]
Further, according to the present invention, the fuel gas supply line having the gas governor interposed therein, the air supply line having the air cleaner interposed upstream, the supply gas from the fuel gas supply line, and the supply air from the air supply line are provided. In a control method of a fuel supply apparatus for a lean combustion gas engine, comprising: a carburetor for mixing; and a balance pipe for communicating an inlet pressure of the carburetor to a loading pressure communication port of the gas governor. A step of detecting a gas pressure using the provided gas pressure detecting means, a step of detecting a load of the gas engine using a load detecting means provided on the output side of the gas engine, and an intake pressure provided in the air supply line Detecting the intake air pressure using the detecting means, and changing the engine load based on the load information detected by the load detecting step. A load variation determination step for determining whether or not there is a load variation, and a step of fixing the air release rate of the open rate variable atmospheric release valve interposed in the balance pipe for a predetermined time when it is determined that there is a load variation in the load variation determination step. , A step of calculating a target gas pressure when it is determined that there is no load variation in the load variation determining step, a gas pressure comparing step of comparing the actual gas pressure with the target gas pressure, and a comparison result in the gas pressure comparing step And a step of changing the air release rate of the open rate variable air release valve.
[0013]
According to the fuel supply control method for a lean combustion type gas engine of the present invention having the above steps, the intake pressure is detected by the intake pressure detecting means (5), and the secondary pressure of the fuel gas (the fuel gas is detected by the gas pressure detecting means (6)). The supply fuel gas pressure between the gas governor 1 and the venturi pipe 3) in the supply line FL) and the load of the gas engine (E) are constantly detected by the load detection means (7), respectively. Based on the detection signal from the means, the control means (8) quickly detects, for example, a sudden change in the load, and determines the air release rate (duty ratio) of the open rate variable air release valve (for example, duty solenoid valve 4). The optimum supply gas pressure can be obtained by appropriately controlling with reference to the gas pressure map prepared in advance (FIG. 4).
Alternatively, it is possible to detect the sudden clogging of the air cleaner and correct the target fuel gas pressure to obtain an optimum supply gas pressure.
[0014]
Specifically, as shown in the gas pressure map of FIG. 4, when the air cleaner is clogged suddenly, the intake pressure that is the loading pressure of the gas governor rapidly decreases, and therefore the supply gas pressure supplied to the carburetor also decreases. (A certain point on the solid line in FIG. 4).
However, the control means (8) calculates and corrects the supply gas pressure (a point on the dotted line in FIG. 4) that should be originally obtained from the relationship between the change over time in the intake pressure and the load. Accordingly, the duty ratio of the duty solenoid valve, that is, the opening ratio to the atmosphere and the opening time are controlled to correct the supply gas pressure.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the accompanying drawings.
[0016]
In FIG. 1, the fuel supply apparatus of this embodiment includes a fuel gas supply line FL having a gas governor 1 interposed therein, an air supply line AL having an upstream air cleaner 2 interposed therein, and a supply from the fuel gas supply line FL. A carburetor 3 that mixes gas and supply air from the air supply line AL; an intake pipe 9 that communicates with the carburetor 3 and a cylinder (not shown) of the lean combustion gas engine E; 3 and a balance pipe BP communicating with the loading pressure communication port 1a of the gas governor 1.
[0017]
The balance pipe BP is provided with a duty solenoid valve 4 having a variable open ratio to the atmosphere.
[0018]
Between the air cleaner 2 and the carburetor 3 in the air supply line AL, an intake pressure detection means (intake pressure sensor: hereinafter, the intake pressure detection means is referred to as an intake pressure sensor) 5 is interposed and input. The control means 8 is connected via a signal line SL1.
[0019]
Between the gas governor 1 and the carburetor 3 in the fuel gas supply line FL, a gas pressure detecting means (gas pressure sensor: hereinafter, the gas pressure detecting means is referred to as a gas pressure sensor) 6 is interposed. The control means 8 is connected via the input signal line SL2.
[0020]
Further, a load detecting means 8 is provided on the output side G of the gas engine E, and a tachometer 11 is provided on the rotating portion directly connected to the crankshaft of the gas engine, and the input signal lines SL3 and SL4 are provided in the order of signs. Connected to the control means 8.
[0021]
Then, the control means 8 uses an output signal line SL5 to obtain an optimum supply gas pressure based on the input signal information of the signal lines SL1 to SL4 and a gas pressure map prepared in advance (see FIG. 4). Thus, the duty solenoid valve 4 is controlled.
[0022]
According to the embodiment of the fuel supply apparatus of the lean combustion gas engine shown in FIG. 1 having such a configuration, the duty solenoid valve 4 mediates the intake pressure as the loading pressure of the gas governor 1, and the fuel gas itself Because it does not communicate, the countermeasures for explosion-proof sealing are minimal.
Further, the duty solenoid valve 4 itself is a general-purpose product and inexpensive, and the entire system is configured simply and inexpensively.
[0023]
Next, a fuel supply control method for a lean combustion gas engine will be described with reference to FIG.
[0024]
First, in step S1, the gas pressure map shown in FIG. 4 is set, and in the next step S2, the secondary gas pressure, that is, the supply gas pressure downstream of the gas governor 1 is detected by the gas pressure sensor 6.
[0025]
In the next step S3, the load detecting means 7 detects the engine load, and the process proceeds to the next step S4.
[0026]
In step S4, the inlet pressure of the carburetor 3 is detected by the intake pressure sensor 5, and the process proceeds to the next step S5.
[0027]
In step S5, the control means 8 determines whether or not there is a load fluctuation in the engine E based on the detected engine load information. If there is a load fluctuation, the process proceeds to step S6, and if there is no load fluctuation. Advances to step S7.
[0028]
In step S6, for example, if the load fluctuates so as to increase, the control means 8 increases the duty ratio of the duty solenoid valve 4, that is, the opening rate of the communication hole 4a with the atmosphere of the duty solenoid valve 4. The duty ratio is controlled so as to be fixed only for a time corresponding to the target load size. Then, the process proceeds to the next step S11.
[0029]
If the control is performed as described above, the loading pressure flowing through the balance pipe BP is corrected as if the intake pressure has increased. Accordingly, the gas governor 1 increases the supply gas amount in conjunction with the correction, and is the supply gas pressure. Secondary gas pressure increases. As a result, the mixed gas of fuel gas and air flowing into the combustion chamber (not shown) becomes rich, and the original purpose (injection of fuel corresponding to the increase in load) is achieved.
[0030]
In step S7, the control means 8 calculates a target gas pressure based on the detection information obtained by the intake pressure sensor 5, the gas pressure sensor 6, the load detection means 7, and the gas pressure map (FIG. 4). The process proceeds to the next step S8.
[0031]
In step S8, the control means 8 determines whether or not the actual gas pressure is higher than the target value. If the actual gas pressure is higher (YES in step S8), the process proceeds to step S9, and if lower (NO in step S8), Proceed to step S10.
[0032]
In step S9, the control means 8 performs control so as to reduce the duty ratio of the duty solenoid valve 4, and as a result, the secondary gas pressure changes so as to decrease, and the control returns to step S2.
[0033]
In step S10, the control means 8 performs control so as to increase the duty ratio of the duty solenoid valve 4. As a result, the secondary gas pressure changes so as to increase, and the control returns to step S2.
[0034]
Here, FIG. 5 shows the load signal and the duty ratio in the control for detecting the load, increasing the duty ratio at the time of turning on the load to make the fuel thicker (in a rich state), and preventing the rotation speed from dropping at the time of turning on the load. It is a characteristic graph which shows the relationship of secondary gas pressure.
The horizontal axis represents elapsed time.
[0035]
FIG. 3 shows another example of the fuel supply control method for the lean burn type gas engine of the present embodiment.
3 differs from FIG. 2 in detecting the engine speed (S22 in FIG. 3) between the gas pressure map setting step (S1 in FIG. 2) and the secondary gas pressure detection step (S2 in FIG. 2). ), A load fluctuation determination step (S5 in FIG. 2), and a target gas pressure calculation step (S7 in FIG. 2), except that a step for determining the presence or absence of rotation fluctuation (S27 in FIG. 3) is added. This is the same as FIG.
[0036]
Here, FIG. 6 detects the engine speed, and when the engine speed becomes lower than the set speed, the duty ratio is fixed to a high value to make the fuel gas (mixed gas) rich (in a rich state). On the other hand, when the rotational speed becomes higher than the set rotational speed, the rotation signal, the duty ratio, and the duty ratio are controlled in a control for returning the rotation by fixing the duty ratio to a low value and thinning the fuel gas (in a lean state). It is a characteristic graph which shows the relationship of secondary gas pressure.
The horizontal axis represents elapsed time.
[0037]
According to the fuel supply control method of the lean combustion type gas engine shown in FIGS. 2 and 3 having such a process, the load pressure detection is performed by the intake pressure sensor 5, the secondary pressure of the fuel gas is detected by the gas pressure sensor 6, and the load detection is performed. The load of the gas engine E is constantly detected by the means 7, and the control means 8 quickly detects, for example, a sudden change in the load based on the detection signals from the three detection means. The duty ratio is appropriately controlled with reference to a gas pressure map prepared in advance (FIG. 4), so that an optimum supply gas pressure can be obtained.
Alternatively, it is possible to detect the sudden clogging of the air cleaner and correct the target fuel gas pressure to obtain an optimum supply gas pressure.
[0038]
It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical contents of the present invention.
[0039]
【The invention's effect】
The effects of the present invention are listed below.
(1) The open rate variable atmospheric release valve mediates the intake pressure as the loading pressure of the gas governor and does not allow the fuel gas itself to communicate, so that the explosion-proof measures and the seal measures are minimal.
(2) The open rate variable air release valve can be used as a general-purpose product, and the entire system is simple and inexpensive.
(3) The intake pressure signal by the intake pressure detection means, the fuel gas secondary pressure signal by the gas pressure detection means, and the load signal by the load detection means are always detected, and the control means is based on the three detection signals, An optimum supply gas pressure can be obtained by quickly detecting the fluctuation of the engine during operation and appropriately controlling the air release rate of the open rate variable air release valve.
(4) It is possible to detect the sudden clogging of the air cleaner and correct the target fuel gas pressure to obtain the optimum supply gas pressure.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a fuel supply device for a lean burn gas engine according to an embodiment of the present invention.
FIG. 2 is a control flowchart showing a flow of fuel supply control in the embodiment of the present invention.
FIG. 3 is a control flowchart showing another example of the flow of fuel supply control in the embodiment of the present invention.
FIG. 4 is a diagram showing a gas pressure map used for fuel supply control in the embodiment of the present invention.
FIG. 5 is a graph showing a relationship between a load signal, a duty ratio, and a secondary gas pressure in the fuel supply control according to the embodiment of the present invention.
FIG. 6 is a graph showing the relationship between the rotation signal, the duty ratio, and the secondary gas pressure in the fuel supply control according to the embodiment of the present invention.
FIG. 7 is a configuration diagram of a fuel supply device for a gas engine in the prior art.
FIG. 8 is a graph showing the relationship between load magnitude, supply gas pressure and air-fuel ratio in the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Gas governor 2 ... Air cleaner 3 ... Carburetor 4 ... Duty solenoid valve 5 ... Intake pressure sensor 6 ... Gas pressure sensor 7 ... Load detection means 8 ... Control means 9 ... Intake pipe 10 ... Throttle valve AL ... Air supply line FL ... Fuel gas supply line BP ... Balance pipe

Claims (2)

A fuel gas supply line provided with a gas governor; an air supply line provided with an air cleaner upstream; a carburetor for mixing supply gas from the fuel gas supply line and supply air from the air supply line; and the carburetor A balance pipe that communicates the inlet pressure of the gas governor with the loading pressure communication port of the gas governor, and a fuel supply device for a lean-burn gas engine, wherein the open rate variable atmospheric release valve interposed in the balance pipe; An intake pressure detecting means interposed between the air cleaner of the air supply line and the carburetor, a gas pressure detecting means interposed between the gas governor of the fuel gas supply line and the carburetor, and a gas engine Load detection means provided on the output side of the intake air pressure signal from the intake pressure detection means and the gas Target gas by driving the opening ratio variable air open valve based on the gas pressure map showing the relationship between the load signal and the set load and feed gas pressure between the gas pressure signal from pressure detecting means from said load detecting means A fuel supply device for a lean combustion type gas engine, characterized by comprising control means for controlling the pressure . A fuel gas supply line provided with a gas governor; an air supply line provided with an air cleaner upstream; a carburetor for mixing supply gas from the fuel gas supply line and supply air from the air supply line; and the carburetor In the control method of the fuel supply device of the lean combustion type gas engine, the gas pressure detection means provided in the fuel gas supply line comprises: a balance pipe communicating the inlet pressure of the gas governor with the loading pressure communication port of the gas governor. The step of detecting the gas pressure using the load detecting means provided on the output side of the gas engine, the step of detecting the load of the gas engine using the load detecting means provided on the output side of the gas engine, and the intake pressure detecting means using the intake pressure detecting means provided on the air supply line. a step of detecting the negative to determine the presence or absence of variation in engine load based on the load information detected by the load detection step A change determining step, a step of fixing the air release rate of the open rate interposed said balance pipe when it is determined that there load change in the load fluctuation determining step variable air release valve a predetermined time, the load variation judgment step The target gas pressure is calculated when it is determined that there is no load fluctuation, the actual gas pressure is compared with the target gas pressure, and the open rate is variable based on the comparison result in the gas pressure comparison step. And a step of changing an air release rate of the air release valve. A control method of a fuel supply device for a lean combustion gas engine.

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