JP3945066B2 - Gas fuel supply device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gaseous fuel supply apparatus that supplies gaseous fuel to an internal combustion engine, and more particularly to a gaseous fuel supply apparatus that is suitable for supplying gaseous fuel to an internal combustion engine used in a vehicle such as an automobile.
[0002]
[Prior art]
Conventionally, as related to a gaseous fuel supply device, as described in JP-A-9-242615, a pressure adjusting means for increasing the fuel gas pressure on the upstream side of the valve with respect to the fuel gas pressure on the downstream side when the valve is closed There has been known a fuel injection valve for gaseous fuel provided with the above. This fuel injection valve is intended to improve the controllability of the valve opening time by reducing the bounce effect of the valve when the valve is closed by the pressure adjusting means.
[0003]
[Problems to be solved by the invention]
However, the above-described gaseous fuel supply technology has a problem that it is difficult to open and close the valve when the fuel gas pressure upstream of the valve becomes a pressure higher than normal. That is, when the upstream fuel gas pressure that presses the valve becomes larger than the electromagnetic force that attracts the valve, it is difficult to open the valve. In particular, at the time of fuel cut, fuel gas is not consumed, so the pressure of the fuel gas tends to be in a high pressure state, and opening and closing of the valve tends to be difficult.
[0004]
Accordingly, the present invention has been made to solve such problems, and an object of the present invention is to provide a gaseous fuel supply device that can smoothly open and close a valve.
[0005]
[Means for Solving the Problems]
That is, the gaseous fuel supply device according to the present invention includes a fuel injection means for supplying pressurized gaseous fuel to the engine by opening and closing a valve, and a pressure detection means for detecting the pressure of the gaseous fuel pumped to the fuel injection means. , Fuel cut means for stopping the supply of gaseous fuel to the engine under certain conditions, and fuel cut for prohibiting fuel cut by the fuel cut means when the pressure detected by the pressure detection means is equal to or higher than a predetermined reference value And prohibiting means.
[0006]
According to the present invention, the fuel cut is prohibited when the pressure of the gaseous fuel pumped to the fuel injection means is equal to or higher than the predetermined reference value, and therefore the pressure of the gaseous fuel increases due to the execution of the fuel cut. Is prevented. Therefore, it is possible to avoid the problem that it becomes difficult to open and close the valve of the fuel injection means due to an increase in the pressure of the gaseous fuel.
In the gaseous fuel supply apparatus according to the present invention, the fuel cut prohibiting means may be configured to cut the fuel cut when the engine speed is smaller than the predetermined speed and the change amount of the engine speed is equal to or greater than the predetermined change amount. It is preferable to prohibit the fuel cut by the means.
In the gaseous fuel supply apparatus according to the present invention, it is preferable that the fuel injection means has a structure in which the pressure of the gaseous fuel acts in a direction to close the injection port with respect to the valve when the valve is closed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
[0008]
FIG. 1 shows a schematic configuration diagram of a gaseous fuel supply apparatus according to this embodiment.
[0009]
As shown in FIG. 1, a gaseous fuel supply device 10 is applied to an internal combustion engine of a vehicle that runs on gaseous fuel, and is a device that supplies gaseous fuel stored in a fuel tank 11 to an engine 12. The fuel tank 11 is composed of a pressure-resistant container, and contains gaseous fuel in a high pressure state. A pipe 13 for pumping gaseous fuel is connected to the fuel tank 11, and the pipe 13 is connected to a first shutoff valve 14, a high pressure sensor 15, a second shutoff valve 16, a first regulator 17, and a third shutoff valve 18. Are sequentially arranged.
[0010]
The first shut-off valve 14, the second shut-off valve 16, and the third shut-off valve 18 are electromagnetic valves and open and close in response to a control signal from the ECU 20. The ECU 20 controls the entire apparatus of the gaseous fuel supply apparatus 10 and is mainly composed of a computer including a CPU, a ROM, and a RAM. Various control routines including a gaseous fuel supply control routine are stored in the ROM.
[0011]
The high pressure sensor 15 detects the pressure displayed on the pressure gauge installed in the driver's seat of the vehicle. The first regulator 17 is a high-pressure regulator, and pressure adjusting means that adjusts the pressure (eg, 200 kg / cm 3) of the gaseous fuel stored in the fuel tank 11 to a low pressure (eg, 4 kg / cm 3).
[0012]
A delivery pipe 21 is connected to the downstream side of the third cutoff valve 18. The delivery pipe 21 distributes the gas fuel fed under pressure to the injectors 22. A pressure sensor 23 is provided in the delivery pipe 21. The pressure sensor 23 is pressure detection means for detecting the pressure of the gaseous fuel sent to the injector 22. A detection signal output from the pressure sensor 23 is input to the ECU 20.
[0013]
The injector 22 is a fuel injection unit that supplies pressurized gaseous fuel to the engine 12 by opening and closing the valve 31, and is installed for each cylinder provided in the engine 12.
[0014]
On the other hand, a check valve 24 is connected between the fuel tank 11 of the pipe 13 and the first shut-off valve 14. Further, a filling valve 25 and a filling port 26 are sequentially arranged on the upstream side of the check valve 24. By providing these check valve 24, filling valve 25 and filling port 26, it becomes possible to replenish the fuel tank 11 with gaseous fuel from the outside of the vehicle.
[0015]
FIG. 2 shows a schematic diagram of the injector 22 of the gaseous fuel supply apparatus 10 according to the present embodiment.
[0016]
As shown in FIG. 2, the injector 22 is provided with a coil 33 in a hollow main body 32. The coil 33 receives a control signal from the ECU 20 and generates an electromagnetic force, and is arranged with the opening direction of the central opening portion directed toward the axial direction of the main body 32. A spout 35 is opened at the tip 34 of the main body 32. A valve 31 is disposed between the ejection port 35 in the main body 32 and the coil 33. The valve 31 is a valve body that opens and closes the ejection port 35, and is biased by the spring 36 so as to close the ejection port 35.
[0017]
In the injector 22, when the supply of the gaseous fuel G is stopped, the coil 33 is not energized, the valve 31 is pressed against the inner surface of the distal end portion 34 by the bias of the spring 36, and the ejection port 35 is closed. On the other hand, when the gaseous fuel G is supplied, the coil 33 is energized, a magnetic field is formed around the end of the coil 33, and an electromagnetic force acts on the valve 31 by the magnetic field. For this reason, the valve 31 moves to the coil 33 side, and the spout 35 is opened. At this time, the gaseous fuel G is pumped from the proximal end side (right side in FIG. 2) of the injector 22, passes through the central opening of the coil 33, passes through the gap between the valve 31 and the inner surface of the distal end portion 34, and the jet outlet 35. Is injected from.
[0018]
In the injector 22 having such a structure, if the pressure of the gaseous fuel G is high when the valve is closed, it may be difficult to open the valve. That is, the pressure of the gaseous fuel G acts on the valve 31 that closes the injection port 35, and the valve 31 is pressed against the tip portion 34. When the pressing force becomes larger than the electromagnetic force of the coil 33, it is difficult to open the valve 31. Therefore, in order to smoothly open and close the valve 31, it is necessary to adjust the pressure of the gaseous fuel G on the upstream side of the valve 31 so as not to be in a high pressure state.
[0019]
Next, the operation of the gaseous fuel supply device will be described.
[0020]
FIG. 3 shows a flowchart of the operation of the gaseous fuel supply apparatus 10. First, in step S10 of FIG. 3 (hereinafter simply referred to as “S10”, the same applies to other steps), it is determined whether or not the idle switch is in an ON state. When it is determined that the idle switch is in the ON state, the process proceeds to S12, where it is determined whether or not a fuel cut is currently being executed. On the other hand, when it is determined that the idle switch is not in the ON state, the process proceeds to S20, where the fuel cut is prohibited, and “0” is stored as the data of the fuel cut flag (exfc).
[0021]
In S12, whether or not the fuel cut is being performed is determined by detecting whether the data stored in the fuel cut flag of the ECU 20 is “1” or “0”, for example.
[0022]
If it is determined in S12 that the fuel cut is being executed, the process proceeds to S14, and whether or not the engine speed (ene) of the engine 12 is smaller than a preset first engine speed reference value (EFCRTNNE). Determined. On the other hand, when it is determined in S12 that the fuel cut is not being executed, the process proceeds to S22.
[0023]
When it is determined in S14 that the engine speed of the engine 12 is smaller than the first reference value, the process proceeds to S16, and the change amount reference value (EFCR) in which the change amount (edlne) of the engine 12 is preset. It is determined whether or not it is above. On the other hand, when it is determined in S14 that the rotational speed of the engine 12 is not smaller than the first reference value, the process proceeds to S18.
[0024]
When it is determined in S16 that the amount of change in the rotational speed of the engine 12 is equal to or greater than the change amount reference value, the process proceeds to S20 and fuel cut is prohibited. On the other hand, when it is determined in S16 that the amount of change in the rotational speed of the engine 12 is not greater than or equal to the change amount reference value, the process proceeds to S18.
[0025]
In S18, it is determined whether or not the pressure (epcng2) of the gaseous fuel upstream of the valve 31 in the injector 22 is equal to or higher than a preset first pressure reference value (EPCNG2FCR). Here, the pressure (epcng2) of the gaseous fuel upstream of the valve 31 in the injector 22 is determined based on the detection signal output from the pressure sensor 23.
[0026]
If it is determined in S18 that the pressure of the gaseous fuel upstream of the valve 31 is equal to or higher than the first pressure reference value, the process proceeds to S20 and fuel cut is prohibited. On the other hand, when it is determined in S18 that the pressure of the gaseous fuel upstream of the valve 31 is not equal to or higher than the first pressure reference value, the control process is terminated. In this case, since the pressure of the gaseous fuel upstream of the valve 31 is not in a high pressure state, there is no concern that it is difficult to open the valve 31, and fuel cut is continuously executed.
[0027]
By the way, in S22, it is determined whether or not the rotational speed (ene) of the engine 12 is equal to or greater than a second rotational speed reference value (NCUT) set in advance. When it is determined that the rotational speed of the engine 12 is not equal to or greater than the second rotational speed reference value, it is determined that the condition for executing the fuel cut is not satisfied, and the control process is terminated.
[0028]
On the other hand, when it is determined that the rotational speed of the engine 12 is greater than or equal to the second rotational speed reference value, the routine proceeds to S26, where the throttle switch operation is not abnormal (exgtafc = OFF) or the throttle switch operation is abnormal. It is determined whether (exgtafc = ON). If it is determined in S26 that the operation of the throttle switch is abnormal, the control process is terminated. On the other hand, when it is determined that the operation of the throttle switch is not abnormal, the process proceeds to S30.
[0029]
In S30, it is determined whether or not the pressure (epcng2) of the gaseous fuel upstream of the valve 31 in the injector 22 is smaller than a preset second pressure reference value (EPCNG2FC). In S30, when it is determined that the pressure of the gaseous fuel upstream of the valve 31 is smaller than the second pressure reference value, the process proceeds to S32 and fuel cut is executed. At this time, “1” is stored as data of the fuel cut flag (exfc).
[0030]
On the other hand, when it is determined in S30 that the pressure of the gaseous fuel upstream of the valve 31 is not smaller than the second pressure reference value, the control process is terminated. In this case, since the pressure of the gaseous fuel upstream of the valve 31 is in a high pressure state, the valve 31 may be difficult to open, and fuel cut is prohibited.
[0031]
As described above, according to the gaseous fuel supply apparatus 10 according to the present embodiment, as shown in FIG. 4, when the fuel cut is not being performed, the pressure (epcng2) of the gaseous fuel on the upstream side of the valve 31 in the injector 22. Is cut only when the pressure is smaller than the second pressure reference value (EPCNG2FC), and the fuel cut is prohibited when the pressure of the gaseous fuel is equal to or higher than the second pressure reference value. On the other hand, when the fuel cut is being executed, the fuel cut is prohibited when the pressure of the gaseous fuel becomes equal to or higher than the first pressure reference value (EPCNG2FCR). For this reason, it can prevent that the pressure of gaseous fuel rises by execution of fuel cut. Therefore, it is possible to prevent the problem that the valve of the fuel injection means cannot be opened due to the increase in the pressure of the gaseous fuel.
[0032]
【The invention's effect】
As described above, according to the present invention, since the fuel cut is prohibited when the pressure of the gaseous fuel sent to the fuel injection means is equal to or higher than a predetermined reference value, the pressure of the gaseous fuel is caused by the execution of the fuel cut. Can be prevented from rising. Accordingly, it is possible to avoid the problem that the valve of the fuel injection means cannot be opened due to the increase in the pressure of the gaseous fuel.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a gaseous fuel supply apparatus according to an embodiment.
FIG. 2 is an explanatory view of an injector of the gaseous fuel supply device according to the embodiment.
FIG. 3 is a flowchart showing the operation of the gaseous fuel supply device according to the embodiment.
FIG. 4 is an explanatory diagram of a gaseous fuel pressure and a fuel cut state in the gaseous fuel supply apparatus according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Gaseous fuel supply apparatus, 12 ... Engine, 22 ... Injector (fuel injection means), 23 ... Pressure sensor (pressure detection means), G ... Gaseous fuel.

Claims (3)

Fuel injection means for supplying pressurized gaseous fuel to the engine by opening and closing a valve;
Pressure detection means for detecting the pressure of the gaseous fuel pumped to the fuel injection means;
Fuel cut means for stopping the supply of the gaseous fuel to the engine under certain conditions;
A fuel cut prohibiting means for prohibiting a fuel cut by the fuel cut means when the pressure detected by the pressure detecting means is equal to or higher than a predetermined reference value;
A gaseous fuel supply device comprising: The fuel cut prohibiting means prohibits the fuel cut by the fuel cut means when the engine speed is smaller than a predetermined speed and the change amount of the engine speed is not less than a predetermined change amount,
The gaseous fuel supply apparatus according to claim 1.   The gaseous fuel supply device according to claim 1 or 2, wherein the fuel injection means has a structure in which the pressure of the gaseous fuel acts in a direction to close the injection port with respect to the valve when the valve is closed.

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