JP2006250149A - Lpg supply device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize supply of LPG to an engine, in an LPG injection system having a liquid phase fuel system and a gas phase fuel system. <P>SOLUTION: An LPG component calculation means 35 calculates a component fraction based on values detected from a tank temperature sensor 33 and a gas phase pressure sensor 25. A liquid phase state determination means 36 determines a state of liquid phase LPG in the liquid phase fuel system FL from a liquid phase pressure sensor 15 and a liquid phase temperature sensor 16 by using the calculated component fraction. The liquid phase fuel system FL supplies fuel when the fuel is completely on the liquid phase, and the liquid phase fuel system FL is switched to the gas fuel system FG when generation of gas phase is determined, so that a correct and precise fuel control is always performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for supplying LPG as fuel to an engine by an injection method, more specifically, a system for injecting LPG in a liquid phase and a system for injecting LPG in a gas phase, and a system according to various conditions of the LPG and the engine. Is selected and a liquid phase or gas phase LPG is supplied to the engine.

  In order to increase the output of an engine using LPG as fuel, it has been proposed to inject into an intake pipe using an injection valve in a high-pressure liquid phase state without vaporization under reduced pressure and supply the engine to the engine.

  As is well known, liquid phase LPG tends to vaporize as the temperature rises, and when the gas phase is generated in the liquid phase fuel system from the fuel tank to the injection valve due to the temperature rise, the pressure fluctuates greatly, Further, since the gas phase fuel is also injected, the injection amount from the injection valve is changed to make the engine malfunction or impossible to operate.

  As a countermeasure, a gas phase fuel system having an injection valve different from the liquid phase fuel system is provided. When no gas phase is generated in the liquid phase fuel system, the liquid phase LPG is injected. JP-A-63-18172 and JP-A-11-210557 suggest that the fuel system to be used should be switched so that gas phase LPG is injected when the gas is generated.

  FIG. 8 is a diagram schematically showing an LPG injection system described in Japanese Patent Laid-Open No. Sho 63-18172, in which a liquid phase injection valve 55 of a liquid phase fuel system 54 is provided in an intake pipe 52 of an engine 51. And a gas phase injection valve 63 of the gas phase fuel system 62 are installed. The liquid phase fuel system 54 includes a pump 57, a pressure sensor 58, and a temperature sensor 59 in a liquid phase fuel passage 56 extending from the fuel tank 53 to the liquid phase injection valve 55, and includes a return passage 60 having a pressure regulator 61. Yes. The gas phase fuel system 62 is provided with a gas phase storage tank 65 in a gas phase fuel passage 64 extending from the return passage 60 or the fuel tank 53 to the gas phase injection valve 63.

  Then, when the pressure and temperature are detected by the pressure sensor 58 and the temperature sensor 59 and it is determined that a gas phase is generated in the liquid phase LPG of the liquid phase fuel passage 56, the liquid phase injection valve 55 is stopped. The gas phase LPG is supplied to the engine 51 by the gas phase injection valve 63.

  FIG. 9 is a diagram schematically showing the LPG injection system described in Japanese Patent Application Laid-Open No. 11-210557, and a liquid-phase fuel system 54 is provided in the intake pipe 52 of the engine 51 in the same manner as in FIG. The liquid phase injection valve 55 and the gas phase injection valve 63 of the gas phase fuel system 62 are provided. The liquid phase fuel system 54 includes a pump 57, a pressure sensor 58, and a temperature sensor 59 in a liquid phase fuel passage 56 extending from the fuel tank 53 to the liquid phase injection valve 55, and includes a return passage 60 having a pressure regulator 61. Yes. On the other hand, the gas phase fuel system 62 is provided with a pressure regulator 66, a pressure sensor 67, and a temperature sensor 68 in a gas phase fuel passage 64 extending from the fuel tank 53 to the gas phase injection valve 63, and further cooling the engine 51. A water temperature sensor 69 for detecting the water temperature is provided.

Then, when the pressure and temperature are detected by the pressure sensor 58 and the temperature sensor 59 and it is determined that a gas phase is generated in the liquid phase LPG of the liquid phase fuel passage 56, the liquid phase injection valve 55 is stopped. The basic operation of supplying the gas phase LPG to the engine 51 by the gas phase injection valve 63 is the same as that of FIG. However, in the case of FIG. 9, the gas phase LPG of the gas phase fuel passage 64 detected by the pressure sensor 67 and the temperature sensor 68, that is, the gas phase depends on whether it is a complete gas phase or an incomplete gas phase. The control mode of the injection valve 63 is changed, and when the high temperature restart is determined by the water temperature sensor 69, the gas phase LPG is supplied to the engine by the gas phase injection valve 63.
JP-A-63-18172 JP-A-11-210557

  The LPG injection system shown in FIGS. 8 and 9 determines the state of the LPG of the liquid phase fuel system, that is, whether the liquid phase is only or whether the gas phase is generated, as described above. This determines whether to continue the supply of the liquid phase LPG or switch to the supply of the gas phase LPG. Therefore, there is a problem that an error in judgment is large depending on the component ratio of LPG, and accurate control becomes difficult.

  Further, when the engine is started, the liquid phase fuel system may not be filled with LPG. In such a case, not only the start by the LPG injection system of FIG. 8 but also the start other than the cold start by the LPG injection system of FIG. It is difficult to accurately determine the state of the LPG in the liquid phase fuel passage, and it is unavoidable that a long time may be required for starting. Further, since the fuel system to be used is selected only depending on the state of the liquid phase LPG of the liquid phase fuel system, if the use of only the liquid phase fuel system is continued, the surplus LPG that has become hot due to the heat in the engine room is converted into the fuel tank. By returning to step S3 and repeating the circulation, the temperature and pressure of the LPG in the fuel tank rise. As a result, a high-precision injection valve is required, and not only a complicated system is required for its control, but also a large pressure resistance is required for each component of the fuel system. In addition, LPG is added to the fuel tank. When it becomes necessary to replenish, there is a problem that filling is difficult if the inside is at a high pressure.

  The present invention has been made to solve the above-mentioned problems of the conventional LPG injection system, and appropriately switches between liquid phase LPG injection and gas phase LPG injection, and In addition to this, it is intended to make the engine start easy and stable, and to further reduce the demand for the injection valve, control system, and pressure resistance by suppressing the temperature and pressure rise of the fuel tank. It is another object of the present invention to provide an LPG injection system in which fuel takeover at the time of switching is performed smoothly.

  The present invention has an LPG injection system having a liquid phase fuel system and a gas phase fuel system that individually inject a liquid phase portion and a gas phase portion of LPG filled in a fuel tank into an intake pipe and supply them to an engine. The above-described problems were solved as follows.

  That is, the present invention provides, as a first means for solving the above problems, a tank temperature sensor that is installed in a fuel tank and detects its temperature; a liquid phase from a liquid fuel tank to a liquid injection valve A liquid phase pressure sensor and a liquid phase temperature sensor installed in the fuel passage for detecting the pressure and temperature of the liquid phase LPG inside the fuel passage; installed in the gas phase fuel passage from the fuel tank of the gas phase fuel system to the gas phase injection valve A gas phase pressure sensor and a gas phase temperature sensor for detecting the pressure and temperature of the gas phase LPG therein; and based on the values detected by the tank temperature sensor and the gas phase pressure sensor or the liquid phase temperature sensor, LPG component calculation means for calculating the component ratio; and based on the component ratio calculated by the LPG component calculation means, from the values detected by the liquid phase pressure sensor and the liquid phase temperature sensor, the liquid phase LPG in the liquid phase fuel system Liquid phase state determining means for determining a state; and when the liquid phase state determining means determines that the liquid phase LPG in the liquid phase fuel system is a complete liquid phase, fuel supply by the liquid phase fuel system is performed. When it is judged that a gas phase is generated in the liquid phase fuel system, fuel supply by the gas phase fuel system is performed.

  As described above, the switching between the liquid phase LPG and the gas phase LPG is determined not only by the pressure and temperature of the liquid phase LPG in the liquid phase fuel system but also by taking into account the composition of the LPG in addition to these. According to the means, there is no determination error due to the difference in the component ratio of LPG, and accurate and highly accurate control is possible. And stable engine performance can be obtained under a wide range of operating conditions.

  Next, according to the present invention, a second means for solving the above problems includes an engine temperature sensor for detecting the temperature of the engine in addition to the first means; an LPG component ratio calculated by the LPG component calculation means; Starting fuel selecting means for selecting a fuel to be supplied at the time of starting the engine based on a value detected by the engine temperature sensor; and the starting fuel selecting means is a liquid phase fuel when the engine temperature at the time of starting is lower than the reference temperature. The starting fuel is supplied to the system, and the starting fuel is supplied to the gas phase fuel system when the temperature is high.

  As described above, according to the second means added to the first means to select the fuel to be supplied at the time of starting as either the liquid phase LPG or the gas phase LPG depending on the engine temperature, in addition to the function of the first means, The engine can always be started easily and stably under all environmental conditions.

  Here, if the starting fuel selection means is designed to extend the starting fuel supply temperature range by the gas phase fuel system by shifting the reference temperature to the lower temperature side as the LPG propane ratio is higher, the starting fuel is appropriately supplied. Thus, the startability of the engine can be further enhanced.

  According to the present invention, there is provided a third means for solving the above problem, a rotational speed sensor for detecting the rotational speed of the engine in addition to the first means or the second means; and a value detected by the rotational speed sensor. And a delay time setting means for setting a time for delaying the fuel supply stop / start timing of the liquid phase fuel system at the time of fuel switching from the fuel supply start / stop timing of the gas phase fuel system. When switching from the phase fuel system to the gas phase fuel system, the former fuel supply is stopped after a delay of a set time from the start of the latter fuel supply, and when switching from the gas phase fuel system to the liquid phase fuel system, the former fuel The latter fuel supply is started after a set time from the supply stop point.

  The present invention is based on injecting the liquid phase LPG into the intake pipe and supplying it to the engine. Under specific conditions, the gas phase LPG is injected into the intake pipe and supplied to the engine. Like a gasoline engine injection valve, it is installed in each intake manifold branch pipe corresponding to each cylinder to improve responsiveness and distribution to each cylinder, and the gas phase injection valve is temporarily used Therefore, a small number should be installed on the upstream side of the liquid phase injection valve in consideration of the cylinder distribution, considering the economic efficiency. It is preferable to install on the side.

  According to the fourth means added to the first means, the second means or the third means that the timing of stopping and starting the fuel supply of the liquid phase fuel system at the time of fuel switching is as described above. In particular, when the liquid-phase injection valve and the gas-phase injection valve are arranged as described above, fluctuations in the air-fuel ratio at the time of fuel switching can be eliminated, and the drivability and exhaust state can be maintained well.

  Here, if the delay time setting means sets the delay time to be shorter as the engine speed increases, the air-fuel ratio fluctuation at the time of fuel switching can be more reliably eliminated.

  As described above, LPG injection comprising a liquid phase fuel system that injects the liquid phase portion of the LPG of the fuel tank into the intake pipe, and a gas phase fuel system that injects the gas phase portion into the intake pipe under specific conditions. In the system, in addition to detecting the pressure and temperature of the LPG in each fuel system, the temperature of the fuel tank is detected and the component ratio of the LPG used is calculated, and this is used as a reference in the liquid phase fuel system According to the present invention, it is determined whether the liquid phase LPG is a complete liquid phase or a gas phase is generated. Even if LPGs having different compositions are used, the liquid phase LPG or the gas phase LPG is always injected. It is possible to obtain a stable engine performance under a wide range of operating conditions by performing accurate control.

  Further, for this, means for selecting the starting fuel based on the engine temperature and the LPG component ratio, and means for forcibly switching the fuel supply by the liquid phase fuel system to the fuel supply by the gas phase fuel system based on the temperature of the fuel tank. According to the present invention, one or more of means for delaying the supply stop / start of the liquid phase fuel system at the time of fuel switching for a time corresponding to the engine rotation speed is delayed from the supply start / stop of the gas phase fuel system The engine can be started easily and stably, the temperature and pressure rise of the fuel tank is suppressed to reduce various requirements for the injection valve, control system, and parts, and the fuel takeover at the time of switching is interrupted and duplicated. It is possible to carry out smoothly without causing any deterioration in engine operability and exhaust state.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a layout view showing an embodiment for implementing an LPG injection system according to the present invention, wherein 1 is an engine, 2 is a throttle body 3, an intake line including an intake manifold 5, 6 is an exhaust line, 7 is a fuel tank composed of a pressure vessel, 8 is an electronic control unit, FL is a liquid phase fuel system, and FG is a gas phase fuel system.

  The liquid phase fuel system FL is immersed in the liquid phase LPG of the fuel tank 7 and further pressurizes the high pressure liquid phase LPG sucked through the filter, and the liquid phase LPG sent from this is sent to the fuel gallery 17. A fuel passage 11, an electromagnetically driven liquid phase shut-off valve 14, a liquid phase pressure sensor 15, a liquid phase temperature sensor 16, and a fuel gallery 17 that are installed in the passage 11 are connected to a fuel gallery 17 and intake air corresponding to each cylinder of the engine 1. Liquid having a liquid phase injection valve 18 installed in each of the branch pipes of the manifold 5 and a liquid phase pressure regulator 20, branched from a location close to the fuel gallery 17 of the liquid phase fuel passage 11 and connected to the fuel tank 7. And a phase return passage 19.

  The liquid phase pressure sensor 15 and the liquid phase temperature sensor 16 are installed at a location close to the fuel gallery 17, and the liquid phase injection valve 18 is installed at a location close to the intake port of the engine 1. By detecting this state and injecting near the engine inlet, an appropriate amount of liquid phase LPG can be supplied to the engine with good response.

  On the other hand, the gas phase fuel system FG includes a gas phase fuel passage 22 having an inlet opening in the gas phase LPG of the fuel tank 7, an electromagnetically driven gas phase shutoff valve 23 installed in the passage 22, a gas phase pressure regulator 24, A gas phase pressure sensor 25, a gas phase temperature sensor 26, and a gas phase injection valve 27 installed at a location near the throttle body 3 in the collection portion of the intake manifold 5 are provided. However, a plurality of gas-phase injection valves 27 may be installed at appropriate locations so that a plurality of gas-phase injection valves 27 can be distributed equally to each cylinder.

  The gas phase pressure sensor 25 and the gas phase temperature sensor 26 are installed near the gas phase injection valve 27 so as to detect the state of the gas phase LPG immediately before injection and supply an appropriate amount of the gas phase LPG to the engine. It has become.

  The engine 1 is provided with an engine temperature sensor 31 for detecting the temperature, generally the temperature of the cooling water, and a rotation speed sensor 32 for detecting the rotation speed. A sensor for detecting the state of the engine 1, such as an oxygen sensor for detecting, an air flow sensor for detecting the intake air amount installed upstream of the throttle valve 4 in the intake pipe 2, and a throttle opening sensor for detecting the position of the throttle valve 4. Similar to the conventional fuel injection control system, the values detected by these are sent to the electronic control unit 8 to control the liquid phase injection valve 18 and the gas phase injection valve 27.

  In this embodiment, in addition to the engine temperature sensor 31 and the rotation speed sensor 32, a tank temperature sensor 33 for detecting the temperature of the LPG filled in the fuel tank 7 is installed. The gas phase pressure regulator 24 is heated by engine cooling water, and can maintain the gas phase and inject from the gas phase injection valve 27 even if the temperature is lowered.

  The electronic control unit 8 stores the relationship between pressure and temperature in accordance with LPG components, specifically the propane component ratio represented by the pressure-temperature diagram shown in FIG. In addition to control variable input / arithmetic processing / control signal output means for fuel ratio control, LPG component calculation means 35, liquid phase state determination means 36, starting fuel selection means 37, switching command means 38, and delay time setting means 39 are provided. include.

  In normal engine operation, when fuel is supplied by the liquid phase fuel system FL, the liquid phase LPG detected by the liquid phase pressure sensor 15 and the liquid phase temperature sensor 16 and the operating state of the engine 1 are used for the liquid. When the phase injection valve 18 is controlled and fuel is supplied by the gas phase fuel system FG, the gas phase LPG detected by the gas phase pressure sensor 25 and the gas phase temperature sensor 26 and the operating state of the engine 1 are determined. The gas phase injection valve 27 is controlled.

  According to the present embodiment, based on the values detected by the tank temperature sensor 33 and the gas phase pressure sensor 25 or the liquid phase pressure sensor 15, the component ratio of the LPG currently filled in the fuel tank 7, the present embodiment Then, the propane component ratio is calculated by the LPG component calculation means 35. This component ratio can be accurately calculated from the pressure-temperature relationship shown in FIG.

  Then, using the calculated component ratio of LPG and the pressure and temperature in the liquid phase fuel system FL detected by the liquid phase pressure sensor 15 and the liquid phase temperature sensor 16, the liquid phase state determination means 36 uses the liquid phase fuel system. The state of the liquid phase LPG in the FL, that is, whether it is a complete liquid phase or a gas phase is determined. In this case, since there is a constant pressure-temperature relationship depending on the component ratio, if the detected pressure and temperature values deviate from this relationship, it is determined that a gas phase is generated, and the liquid-phase fuel is generated. The fuel supply by the system FL is stopped and switched to the fuel supply by the gas phase fuel system FG.

  The above is an embodiment of the first means described in claim 1, and by adding the composition of the currently used LPG to the element for determining the state of the liquid phase LPG in the liquid phase fuel system FL, The determination error due to the difference in the component ratios is eliminated, and accurate and highly accurate control is possible, and the inconvenience that the fuel supply by the liquid phase fuel system FL is continued even after the gas phase is generated and the mixture is excessively thin is eliminated. Stable engine performance can be obtained under a wide range of operating conditions.

  Next, when starting the engine, the start fuel selection means 37 uses the LPG component ratio calculated by the LPG component calculation means 35 and the engine temperature detected by the engine temperature sensor 31 to select either the liquid phase LPG or the gas phase LPG. Select whether to start with. That is, as shown in FIG. 3, when the engine temperature is lower than the reference temperature TE, the engine is started with the liquid phase LPG supplied from the liquid fuel system FL, and when the engine temperature is higher than the reference temperature TE, the gas phase fuel system is used. It is started with the gas phase LPG supplied from the FG. As a result, the liquid phase LPG is supplied in a low temperature range where the liquid phase LPG is hard to vaporize, and the engine 1 can always be easily and stably started under all environmental conditions. Note that after the engine is started, fuel is supplied according to the determination of the liquid phase state determination means 36.

  In the present embodiment, the reference temperature TE is variable according to the LPG component ratio. That is, as shown in FIG. 4, the higher the ratio of propane in the LPG component ratio calculated by the LPG component calculating means 35, the more the reference temperature TE is shifted to the lower temperature side and the starting temperature range by the gas phase LPG is expanded. On the other hand, the lower the ratio of propane, the higher the reference temperature TE is shifted to the higher temperature side, thereby extending the starting temperature range by the liquid phase LPG.

  The above is the embodiment of the second means described in claim 2, and the startability of the engine 1 can be further improved by changing the reference temperature TE according to the difference in vapor pressure due to the LPG component ratio.

  When the engine 1 is operated for a long time or in a high temperature atmosphere, the excess liquid phase LPG heated by the surroundings of the engine 1 is heated to the fuel tank 7 through the liquid phase return passage 19. Returning and circulating, the temperature of the fuel tank 7 gradually increases. When the temperature of the fuel tank 7 rises, vaporization of the filled LPG advances and the pressure rises significantly.

  The temperature of the fuel tank 7 is detected by a tank temperature sensor 33. When the temperature is lower than a preset reference temperature TF as shown in FIG. 5, the fuel supply by the liquid phase fuel system FL is continued, but from the reference temperature TF. When the temperature becomes too high, the fuel supply is switched to the gas phase fuel system FG. This switching is performed by the switching command means 38 comparing the temperature detected by the tank temperature sensor 33 with the reference temperature TF and issuing a command, so that the liquid phase state determining means 36 completes the liquid phase fuel system FL. Even if it is determined as the liquid phase LPG, the switching is forcibly performed in preference to this determination.

  By consuming the gas phase LPG in the fuel tank 7, the pressure in the fuel tank 7 decreases, the evaporation amount of the liquid phase LPG increases significantly, and the temperature of the fuel tank 7 decreases due to the cooling effect due to the latent heat of vaporization during evaporation. To do. As described above, the increase in the temperature and pressure of the fuel tank 7 is suppressed, so that the liquid phase injection valve 18 and the gas phase injection valve 27 do not require a high processing accuracy and a complicated operation control system, and the liquid phase fuel. It is possible to reduce the requirements for the pressure strength of the components of the system FL and the gas-phase fuel system FG, and it is possible to easily perform the filling operation when the fuel tank 7 is replenished with LPG.

  When the temperature of the fuel tank 7 falls below the reference temperature TF, the fuel supply is returned to the fuel phase according to the determination of the liquid phase state determination means 36. The reference temperature TF in this embodiment may be fixed to a constant value. However, the higher the propane ratio in accordance with the LPG component ratio, the lower the propane ratio, the lower the temperature range for switching to the gas phase LPG. You may make it expand, and if it does in this way, the rise in the temperature and pressure in the fuel tank 7 can be suppressed further appropriately.

  Further, as in the embodiment shown in FIG. 1, a liquid-phase injection valve 18 of a liquid-phase fuel system FL that is normally used is installed near the engine inlet for each intake manifold branch pipe, and the gas-phase fuel system used under specific conditions In the case where the FG gas-phase injection valve 27 is installed in the intake manifold assembly, if the fuel supply stop by the liquid-phase fuel system FL and the fuel supply start by the gas-phase fuel system FG are performed simultaneously, the gas-phase injection valve 27 Is far from the engine 1, causing a supply delay, and the air-fuel mixture temporarily becomes thin. Further, when the fuel supply by the gas phase fuel system FG is stopped and the fuel supply by the liquid phase fuel system FL is started at the same time, the gas phase LPG and the liquid phase LPG are generated because the liquid phase injection valve 18 is close to the engine 1. At the same time, the mixture is temporarily over-rich.

  FIG. 6B shows this situation, and causes the inconvenience that the air-fuel ratio spikes at the time of switching to deteriorate the engine operability and the exhaust state.

  Therefore, when switching is performed in accordance with commands issued by the liquid phase state determination unit 36 and the switching command unit 38, the delay time setting unit 39 uses the delay time setting unit 39 to stop and start the fuel supply of the liquid phase fuel system FL based on the value detected by the rotation speed sensor 32. A time for delaying the timing from the fuel supply start / stop timing of the gas phase fuel system FG is set, and the fuel supply stop and start of the liquid phase fuel system FL are delayed according to the set delay time.

  That is, when switching from the liquid phase fuel system FL to the gas phase fuel system FG, the fuel is interrupted by stopping the fuel supply by the liquid phase fuel system FL slightly after the start of fuel supply by the gas phase fuel system FG. Without being supplied to the engine 1. Further, when switching from the gas phase fuel system FG to the liquid phase fuel system FL, the fuel supply from the liquid phase fuel system FL is started by starting the fuel supply by the liquid phase fuel system FL with a slight delay from the stop of the fuel supply by the gas phase fuel system FG. Can be supplied to the engine 1 without overlapping.

  In setting the delay time by the delay time setting means 39, as shown in FIG. 7, the higher the engine speed, the shorter the delay time is set, resulting in fuel interruption and duplication regardless of the rotational speed. It is effective not to let it.

  The above is an embodiment of the third means described in claims 3 and 5, and as shown in FIG. 6 (A), the occurrence of an air-fuel ratio spike at the time of switching is eliminated, and an air-fuel mixture with a constant air-fuel ratio is supplied to the engine 1. To maintain good operability and exhaust state.

The layout which shows embodiment of this invention. The pressure-temperature diagram of LPG. The figure explaining the starting fuel selection by engine temperature. The figure which shows the relationship between the engine reference temperature of start fuel selection, and a LPG component ratio. The figure explaining the use fuel switching by fuel tank temperature. The figure explaining the relationship between switching of liquid phase LPG and gaseous-phase LPG, and an air fuel ratio. The figure which shows the relationship between the delay time setting of fuel switching, and an engine speed. The schematic arrangement drawing of a prior art example. The schematic arrangement drawing of a different conventional example.

Explanation of symbols

1 engine, 2 intake pipe, 7 fuel tank, 8 electronic control unit, 11 liquid phase fuel passage, 15 liquid phase pressure sensor, 16 liquid phase temperature sensor, 18 liquid phase injection valve, 22 gas phase fuel passage, 25 air Phase pressure sensor, 26 gas phase temperature sensor, 27 gas phase injection valve, 31 engine temperature sensor, 32 rotation speed sensor, 33 tank temperature sensor, 35 LPG component calculation means, 36 liquid phase state determination means, 37 start fuel selection means, 38 switching command means, 39 delay time setting means, FL liquid phase fuel system, FG gas phase fuel system,

Claims (5)

  The fuel tank has a liquid phase fuel system and a gas phase fuel system that select either the liquid phase part or the gas phase part of the LPG filled in the fuel tank, inject it into the intake pipe and supply it to the engine. A tank temperature sensor installed in the fuel tank for detecting the temperature thereof, and a pressure of the liquid phase LPG installed in the liquid phase fuel passage from the fuel tank of the liquid phase fuel system to the liquid phase injection valve. And a liquid phase pressure sensor and a liquid phase temperature sensor for detecting the temperature, and a pressure and temperature of the gas phase LPG installed in the gas phase fuel passage from the fuel tank of the gas phase fuel system to the gas phase injection valve A gas phase pressure sensor and a gas phase temperature sensor for detecting the LPG component, and an LPG component calculation means for calculating a component ratio of LPG based on each value detected by the tank temperature sensor and the gas phase pressure sensor or the liquid phase pressure sensor; ,in front Liquid phase state determining means for determining the state of the liquid phase LPG in the liquid phase fuel system from each value detected by the liquid phase pressure sensor and the liquid phase temperature sensor with reference to the component ratio calculated by the LPG component calculating means. And when the liquid phase state determination means determines that the liquid phase LPG in the liquid phase fuel system is a complete liquid phase, the fuel supply by the liquid phase fuel system is performed, and the liquid phase fuel system An LPG supply device for an engine, characterized in that when it is determined that a gas phase is generated, fuel is supplied by the gas phase fuel system.   2. The engine LPG supply apparatus according to claim 1, wherein an engine temperature sensor for detecting an engine temperature, an LPG component ratio calculated by the LPG component calculation means, and a value detected by the engine temperature sensor are used. Starting fuel selecting means for selecting a fuel to be supplied at the time of starting, and the starting fuel selecting means causes the liquid phase fuel system to supply starting fuel when the engine temperature at the time of starting is lower than a reference temperature. An engine LPG supply system characterized in that the gas-phase fuel system is supplied with starting fuel.   3. The engine LPG supply apparatus according to claim 1 or 2, wherein a rotation speed sensor for detecting a rotation speed of the engine and a fuel supply of the liquid phase fuel system at the time of fuel switching according to a value detected by the rotation speed sensor. Delay time setting means for setting a time for delaying the stop / start timing from the fuel supply start / stop timing of the gas phase fuel system, the delay time setting means from the liquid phase fuel system to the gas phase fuel system At the time of switching, the former fuel supply is stopped after a delay set from the latter fuel supply start time, and only the time set from the former fuel supply stop time at the time of switching from the gas phase fuel system to the liquid phase fuel system. An LPG supply device for an engine, wherein the latter fuel supply is started with a delay.   The liquid phase fuel system liquid phase injection valve is installed in each of the intake manifold branch pipes of the intake line corresponding to each cylinder of the engine, and the gas phase fuel system has one gas phase injection valve. The LPG supply device for an engine according to claim 1, 2 or 3, wherein the LPG supply device is installed at an intake manifold collecting portion of the intake pipe or at an upstream side thereof. 4. The engine LPG supply apparatus according to claim 3, wherein the delay time setting means sets the delay time to be shorter as the engine speed is higher.

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