JP4494943B2 - Engine gas fuel supply device - Google Patents

Description

  The present invention relates to a gas fuel supply device for reducing and evaporating gas fuel filled in a pressure vessel to a pressure of about atmospheric pressure or a predetermined positive pressure by a vaporizer, and sending the gas fuel to an intake pipe and supplying the gas fuel to an engine. In particular, the present invention relates to a gas fuel supply device for an engine having an impurity removal mechanism for removing impurities such as tar and oil stored in a vaporizer.

  As a device that supplies gas fuel, generally liquefied petroleum gas (LPG) or compressed natural gas (CNG) to the engine, the high-pressure gas fuel filled in the pressure vessel is adjusted to about atmospheric pressure with a vaporizer (regulator), and the intake air An apparatus for supplying to an engine by sucking at a mixer portion of a pipe line or adjusting to a predetermined positive pressure and injecting with an injector is well known.

  FIG. 4 shows a layout diagram of a gas fuel supply system provided with a conventional gas fuel supply device. The vaporizer 50 depressurizes the high-pressure gas fuel fed from the pressure vessel 1 to a pressure higher than the atmospheric pressure. And a secondary chamber 530 that is further depressurized to a pressure of about atmospheric pressure or a predetermined positive pressure, and the gas fuel sufficiently decompressed and vaporized in the secondary chamber 530 is supplied to the intake pipe. It is sent to the path 4a.

  By the way, impurities such as tar and oil are mixed in the gas fuel from a purification process and a pump during transportation. This impurity is extracted when the gas fuel is heated and vaporized in the paperizer, but due to its high viscosity, it hardly flows downstream and remains mainly in the secondary chamber of the vaporizer.

  This residual impurity impedes the operation of the diaphragm in the pressure adjusting chamber, or the rubber material of the diaphragm is deteriorated, thereby impairing its function. It is done. In this case, in the fuel supply system in which the gas fuel is adjusted to a predetermined positive pressure and injected from the injector, manual impurity discharging means cannot be provided from the viewpoint of safety.

  As a discharge means for discharging impurities including tar and oil, a drain valve is provided at the bottom of the secondary chamber (pressure-regulating chamber) that decompresses gas fuel to about atmospheric pressure. It is performed to discharge this by making it valve. However, this periodic discharge requires manual opening and closing of the drain valve, which requires a lot of trouble for maintenance. Even if periodic discharge is performed, the time to be discharged differs depending on fluctuations in the amount of impurities stored within a predetermined period, which may cause unnecessary discharge work or delay the discharge timing in some cases. Sometimes.

  On the other hand, in Japanese Patent Application Laid-Open No. 2004-218896, a transparent hose is connected to an impurity storage chamber provided in a vaporizer, and this is determined by the height of the liquid level of impurities in the LPG deposited here or the amount of impurities deposited. The technology that makes it possible to grasp the maintenance time when wastewater should be discharged is proposed. By using this technique, it becomes easy to optimize the timing of impurity discharge work. However, even in this case, if the maintenance person forgets the valve in the open state, a trouble that the engine cannot be started occurs.

  Therefore, in Japanese Patent Application Laid-Open No. 2004-251204, an impurity discharge valve that is controlled to open and close by an electronic control unit is provided in the impurity discharge passage of the vaporizer, and the amount of impurities accumulated in the pressure control chamber by the electronic control unit is allowed. Judging whether or not the range has been exceeded, when it is determined that the allowable range has been exceeded, the impurity discharge valve is temporarily opened, and impurities are discharged to an impurity collection container or oil pan provided separately from the regulator. Technology has been presented. This technique does not worry about forgetting to close the discharge valve and can automatically discharge impurities at an appropriate timing, so that the burden on the maintenance person can be greatly reduced.

However, since this technology discharges impurities to an impurity recovery container or oil pan, the gas fuel will also flow out by opening the impurity discharge valve, resulting in waste of gas fuel or in the environment. Problems such as being discharged. Further, the gas fuel flows out when the discharge valve is opened, which causes a variation in the air-fuel ratio of the gas fuel supplied to the engine, and causes engine malfunction. This problem is particularly prominent in a fuel supply system for injecting a positive pressure vaporized gas.
Japanese Patent Application Laid-Open No. 2004-218496 JP 2004-251204 A

  The present invention is intended to solve the above problems, and automatically removes impurities stored in the vaporizer at an appropriate timing without waste of gas fuel and minimizes the influence on engine operation. As a limit, it is an object to be able to maintain the supply of gas fuel to the engine in a suitable state while reducing the labor of maintenance.

  Accordingly, the present invention provides a vaporizer for decompressing and vaporizing high-pressure gas fuel introduced from a high-pressure vessel, a fuel delivery path for transporting the decompressed and vaporized gas fuel and delivering it to the intake pipe of the engine, and a vaporizer adjustment. An impurity discharge passage connected to the bottom of the pressure chamber, a discharge valve for opening and closing the impurity discharge passage, and a control means for controlling the opening and closing of the discharge valve, and this discharge at a predetermined timing. In the gas fuel supply apparatus in which impurities derived from gas fuel stored in the vaporizer are removed by temporarily opening the valve, this impurity discharge mechanism is opened at the end of the impurity discharge path into the intake pipe. At the same time, the control means controls to open the discharge valve in the engine high load region. And it shall automatically discharged into the intake conduit to the.

  As a result, the impurities are discharged by the automatic control of the discharge valve by the control means, and the impurities are sucked into the engine together with the gas fuel, so that it is not necessary to dispose of the impurities. The maintenance effort involved is greatly reduced. Further, at that time, gas fuel flows out and is sucked into the engine as impurities are discharged, and the timing is set at the time of high load operation of the engine, so that the air-fuel ratio fluctuation due to this can be reduced.

  Moreover, if the discharge of impurities is caused by opening the discharge valve by determining the impurity discharge timing based on the result of the control means integrating the operating time of the engine, the impurity discharge operation will be performed in a timely manner. And it becomes an appropriate amount, so that the operation is not wasted.

  Further, in a gas fuel supply apparatus equipped with an electronically controlled injector at the end of the fuel delivery path, if the opening of the discharge valve is intermittently performed in synchronization with the injection cycle of the injector, the gas accompanying impurity discharge Since the outflow of fuel coincides with the combustion timing of the engine and is efficiently used in combustion, the influence on the air-fuel ratio is further reduced and the waste of gas fuel is reduced. In addition, when the impurities are discharged by opening the discharge valve, if the injector is operated with a pulse width obtained by subtracting the operation pulse width of the discharge valve from the drive pulse width of the injector, Since the total amount of gas fuel supplied to the fuel tank hardly fluctuates, the influence on the air-fuel ratio can be minimized.

  According to the present invention in which the discharge valve of the impurity discharge passage connected to the intake pipe is controlled to be opened / closed by the control means, impurities stored in the vaporizer are automatically removed at an appropriate timing, so that no maintenance work is required and gas fuel is used. As a result, the gas fuel is supplied to the engine in a suitable state by assuming that the engine is discharged during high-load operation of the engine and that the influence on the engine operation is small.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a layout of a gas fuel supply system for an engine using LPG as a gas fuel according to the present embodiment, and a pressure vessel (fuel tank). 1 is connected to a primary chamber 51 of a vaporizer 5 (regulator) by a fuel supply line 9A, and an electromagnetically driven fuel cutoff is provided at two locations of the fuel supply line 9A, a portion near the pressure vessel 1 and a portion near the vaporizer 5. Valve 3 is installed.

  The gas fuel that has entered the primary chamber 51 passes through the communication hole 52 that is opened and closed by the secondary chamber valve 54a, is held in the secondary chamber 53 by being reduced to a predetermined positive pressure, and passes through the fuel delivery path 9B. 6 is injected into the intake pipe 4 a of the engine 4.

  Referring to the sectional view of FIG. 2 showing the details of the vaporizer 5, the secondary chamber valve 54a is provided on the valve lever 54d engaged with the diaphragm 54b, and depends on the pressure of the secondary chamber 53 and the spring load of the spring 54c. The communication hole 52 is opened and closed in accordance with the change in the diaphragm 54b. The lower part of the secondary chamber 53 forms an impurity storage chamber 55, an impurity discharge passage 7 is opened in the bottom wall, and the end is opened in the intake pipe 4a.

  An electromagnetically driven discharge valve 8 is disposed near the base end of the impurity discharge passage 7 and is connected to the electronic control unit 10 (see FIG. 1), and is controlled to be opened and closed by its command. Yes. The electronic control unit 10 is a well-known electronic control unit that controls the opening and closing of the injector 6 in order to supply gas fuel required by the engine at an appropriate air-fuel ratio. A function for adjusting the injection amount of the accompanying injector 6 is added. The impurity storage chamber 55, the impurity discharge passage 7, the discharge valve 8, and the electronic control unit 10 constitute an impurity removal mechanism.

  Hereinafter, the operation of the present embodiment will be described in detail.

  The gas fuel that has entered the secondary chamber 53 is depressurized and vaporized, adjusted to a predetermined positive pressure, and sent to the injector 6. However, the gas fuel, particularly the LPG used in this embodiment, is refined. Impurities such as tar and oil are mixed from pumps during process and transportation, and extracted by heating and vaporizing the gas fuel in the paperizer, and the impurity storage chamber provided below the secondary chamber 53 55 is stored.

  If the accumulated impurities exceed a predetermined amount, the movement of the diaphragm 54b is inhibited or the rubber film is deteriorated. Therefore, when the predetermined amount is reached, the discharge valve 8 disposed in the impurity discharge passage 7 is opened. In this embodiment, the method for controlling the discharge valve 8 is also characterized.

  That is, the electronic control unit 10 accumulates the engine 4 operation time from the previous discharge and stores it in the storage means, and determines this as the impurity discharge timing when this reaches a preset reference time. Then, the control is performed so that the discharge valve 8 is opened at the time of the first high engine load after the determination (for example, determined by the engine speed and the engine boost).

  The discharge valve 8 is opened intermittently in a predetermined number of times, which is performed in synchronization with the timing of the LPG injection valve drive signal of the injector 6. When the discharge valve actuation signal is synchronized with the LPG drive signal, the waveform as shown in FIG. 3A is obtained. In this embodiment, as shown in FIG. 10 outputs the LPG injection valve drive signal to the discharge valve 8 as a pulse width Tx obtained by subtracting the pulse width Tt of the discharge valve operation signal from the pulse width Ti, and controls the opening and closing.

  By adopting such control, even if the outflow of gas fuel containing impurities due to the operation of the discharge valve 8 overlaps the injection of gas fuel by driving the injector 6 at the time of impurity discharge, As shown in FIG. 3B, these total times hardly change, and therefore the amount of gas fuel supplied into the intake pipe 4a hardly changes. That is, since the air-fuel ratio of the gas fuel supplied to the engine 4 is hardly changed by the impurity discharging operation, the operability of the engine 4 is improved by maintaining the gas fuel supply to the engine in a suitable state. It is easy to maintain.

  In addition, the means for collecting impurities including tar and oil in an impurity storage container other than the vaporizer required time and effort to dispose of it periodically. In the form, since the impurities are completely burned in the engine 4, the labor and cost are not required. Further, in the technology for discharging impurities together with the gas fuel, the gas fuel is wasted or discharged into the ambient atmosphere, whereas in this embodiment, all the gas fuel discharged together with the impurities is engine. Since it is used for combustion for driving, it is extremely wasteful.

  Even in a gas fuel supply system in which gas fuel is decompressed to about atmospheric pressure by a vaporizer and sucked by the mixer portion of the intake pipe, the electronic control unit opens the discharge valve for discharging impurities when the engine is under high load. By adopting such a configuration, it is possible to automatically remove impurities at an appropriate timing without wasting gas fuel in the same manner as described above. Further, the fuel to be used is not limited to LPG, and the present invention can be applied to all gas fuels in which impurities are accumulated in the vaporizer.

1 is a layout diagram showing a gas fuel supply system according to an embodiment of the present invention. Sectional drawing which shows the detail of the vaporizer of FIG. (A) is a wave form diagram at the time of synchronizing a discharge valve operation signal with a LPG injection valve drive signal, (B) is a wave form diagram of a LPG injection valve drive signal and a discharge valve operation signal in this embodiment. The layout which shows the gas fuel supply system in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure vessel, 3 Fuel cutoff valve, 4 Engine, 4a Intake pipe line, 5 Vaporizer, 6 Injector, 7 Impurity discharge passage, 8 Discharge valve, 10 Electronic control unit, 51 Primary chamber, 52 Communication hole, 53 Secondary chamber, 54a secondary chamber valve, 55 impurity storage chamber,

Claims (3)

Connected to the vaporizer that depressurizes and vaporizes the high-pressure gas fuel introduced from the high-pressure vessel, the fuel delivery path that transports the decompressed and vaporized gas fuel and sends it out to the intake pipe of the engine, and the bottom of the pressure regulator chamber of the vaporizer an impurity discharging mechanism impurities discharge passage and said impurity discharge passage having a control means for opening and closing control of the exhaust valve and exhaust-off valve for opening and closing, which is provided with a said impurity discharge mechanism, said impurity discharge passage ends Is opened in the intake pipe, and the control means is controlled to open the exhaust valve in an engine high load region, and impurities derived from the gas fuel stored in the vaporizer are removed from the gas fuel. automatically discharged to the intake channel together with, in the gas fuel supply apparatus provided with an injector of the electronically controlled in serial fuel delivery path ends, wherein Off valve is controlled so as to intermittently open in synchronization with the injection period of the injector, gas fuel supply apparatus characterized by. The gas fuel supply apparatus according to請Motomeko 1, when the impurity emissions from the opening of the discharge valve, driving the injector pulse width of a portion obtained by subtracting the operating pulse width of the discharge valve from the driving pulse width of the injector A gas fuel supply device, characterized in that: Before SL control means, characterized in that for opening the exhaust valve determines the timing of the impurities discharged based on the result obtained by integrating the operating time of the engine, the gas fuel supply apparatus according to claim 1 or 2 .

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