JP2005351189A - Device for supplying gaseous lpg to engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for supplying gaseous LPG to an engine by which liquid LPG in a fuel tank is delivered to a vaporizer to be adjusted to gaseous LPG of a specified positive pressure and injected from a fuel injection valve, and in the case when delivery at its own pressure at low-temperature time is insufficient, a forcible delivery is conducted by a fuel pump to ensure a start-up of the engine. <P>SOLUTION: A fuel-tank pressure is sensed by a pressure sensor 12 provided in the fuel tank 2. The sensed pressure is compared with a specified value which is preset in an electronic controller 10A so as to judge whether or not a maximum flow-rate of the fuel required by the engine can be supplied by the delivery at its own pressure without depending on the fuel pump 5. When the detected pressure is lower than the prescribed value, the fuel is forcibly delivered by operating the fuel pump 5. Thus, startability of the engine at the time of low temperature is ensured. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus that supplies liquid LPG to an engine by vaporizing and depressurizing liquid LPG to a predetermined positive pressure, and in particular, a fuel tank pressure decreases due to a drop in vapor pressure at low temperatures, and fuel The present invention relates to a gas LPG supply device comprising means for forcibly sending a liquid LPG in a fuel tank and supplying it to an engine when self-pressure delivery from the tank is insufficient or impossible.

  LPG has been conventionally used as a fuel for spark ignition engines. As a supply method thereof, as described in, for example, Japanese Patent Laid-Open No. 6-17709, liquid LPG is adjusted to vaporized gas having a predetermined positive pressure, and an intake pipe is used. A method of injecting into a road is widely known. In this system, it is customary to use the heat of engine cooling water as means for heating and vaporizing the liquid LPG, and self-pressure using its own vapor pressure as means for pumping the liquid LPG in the fuel tank to the vaporizer. A supply method is used.

  However, in the self-pressure supply method using the vapor pressure of the LPG itself in the fuel tank, the LPG vapor pressure in the fuel tank is lowered at low temperatures and the output power is insufficient, leading to deterioration of engine operability due to fuel shortage. There is. Or, in the case of LPG having a large amount of butane component or at an extremely low temperature, fuel may not be supplied at all and engine stall may occur or start-up may not be possible.

  In order to solve this problem, Japanese Patent Application Laid-Open No. 2002-302111 discloses a gas LPG supply device in which liquid LPG in a fuel tank is pressurized and delivered using a low-pressure feed pump at an extremely low temperature. According to this apparatus, the fuel can be supplied even at an extremely low temperature, and the fuel is supplied only by the pressure in the fuel tank without operating the low-pressure feed pump at the normal time.

However, this device uses a low-pressure feed pump as a fuel feed assisting means to the plunger pump that drives the engine that measures LPG to the required fuel amount and pumps it toward the intake pipe. Therefore, it is inevitable that the entire apparatus becomes complicated. In addition, the low-pressure feed pump operates at an extremely low temperature, and does not sufficiently cope with all situations where the self-pressure feed output is insufficient. In addition, if the required fuel flow rate increases while the low-pressure feed pump is stopped, there is a concern that depending on the structure of the pump, this may cause passage resistance and supply the required amount of fuel.
JP-A-6-17709 JP 2002-302111 A

  The present invention is intended to solve the above-mentioned problems, and even when the pressure in the fuel tank is lowered, the liquid LPG necessary for engine operation is sent out, and in addition, the self-pressure is delivered by the pressure in the fuel tank. It is an object of the present invention to provide a gas LPG supply device that does not cause fuel shortage and that has a simple configuration capable of maintaining good engine operability.

  The present invention solves the above problem by providing an engine gas LPG supply device that sends liquid LPG in a fuel tank to a vapor pressure adjusting means and injects the fuel LPG as a predetermined positive pressure gas LPG from a fuel injection valve into an intake pipe as follows. I decided to solve it.

  That is, a fuel pump provided in a fuel delivery line from the fuel tank to the vapor pressure adjusting means, a fuel tank pressure detecting means for detecting the pressure of the fuel tank, and a fuel pump operation determination based on the detected fuel tank pressure. The fuel pump operation determining means is provided, and the fuel pump operation determining means is operated when the fuel tank pressure detected by the fuel pump is lower than a predetermined value set in advance and stopped when it is higher. One means.

  Alternatively, a fuel pump provided in a fuel delivery line from the fuel tank to the vapor pressure adjusting means, a fuel tank temperature detecting means for detecting the temperature of the fuel tank, and a fuel pump operation determination based on the detected fuel tank temperature. The fuel pump operation determining means is provided, and the fuel pump operation determining means is operated when the fuel tank temperature detected by the fuel pump is lower than a predetermined value set in advance and stopped when it is higher. Two measures were taken.

  The fuel tank pressure is detected by presetting the boundary pressure as to whether or not the engine required maximum fuel flow rate can be secured by sending out the liquid LPG in the fuel tank by self-pressure. The pressure in the fuel tank is estimated directly from the temperature detected by the fuel tank temperature detection means, and the necessity of the fuel pump operation is judged based on the result of judging whether the fuel pump is necessary or not. Only when the fuel pump is operated, the liquid LPG is forcibly sent out and sent to the vaporization pressure adjusting means, so that the engine start at the low temperature and the subsequent engine operation can be ensured.

  Also, a fuel pump provided in a fuel delivery line from the fuel tank to the vapor pressure adjusting means, a fuel tank pressure detecting means and a fuel tank temperature detecting means for detecting the pressure and temperature of the fuel tank, respectively, and the detected fuel tank pressure And a fuel pump operation determining means for determining the operation of the fuel pump based on the fuel tank temperature, and the fuel pump operation determining means is provided in advance for each of at least one of the fuel tank pressure and the fuel tank temperature detected by the fuel pump. The third means for solving the problem is that the system is activated when it is lower than a predetermined value and is stopped when both are higher.

  Alternatively, instead of setting a predetermined value for determining the fuel pump operation in the third means in advance, the LPG composition is estimated based on the fuel tank pressure and the fuel tank temperature, and each of determining the operation of the fuel pump is determined. The predetermined value is determined according to the LPG composition, and at least one of the detected fuel tank pressure and fuel tank temperature is lower than the predetermined value determined for each, and both are stopped when both are higher This was the fourth means of solving the problem.

  In this way, by determining whether the fuel pump operation is necessary or unnecessary from both the pressure and temperature of the fuel tank, the fuel pump can be appropriately operated when necessary, and the engine can be started more reliably. In particular, according to the fourth means for determining the necessity / unnecessity of the fuel pump operation by estimating the LPG composition, the fuel pump can be further qualified because the predetermined value can be set to an optimum value for the LPG used. Can be operated.

  Here, in carrying out the present invention, the first, second, third and fourth means are provided with a pressure regulator, and a return line for returning liquid LPG exceeding the required fuel flow rate to the fuel tank is branched from the fuel delivery line. It is suitable to provide. As a result, an excessive primary pressure is prevented from acting on the vapor pressure adjusting means that makes the liquid LPG a predetermined positive pressure gas LPG, and excessive liquid LPG exceeding the vaporization capacity is sent to the vapor pressure adjusting means. Is prevented.

  Also, for the first and third means, a predetermined value of the fuel tank pressure, which is a criterion for determining whether the fuel pump is operating or stopped, is set to a low value within a range in which the engine required maximum fuel flow rate is ensured. Setting a predetermined value of the fuel tank temperature, which is a criterion for determining whether the fuel pump is activated or stopped, to a high value corresponding to the LPG composition with a low vapor pressure ensures a fuel supply at a low temperature while ensuring the fuel supply. This is preferable in that the operation is not performed more than necessary. Further, a predetermined value for each of the fuel tank pressure and the fuel tank temperature for determining the operation / stop of the fuel pump for the fourth means is determined by correcting according to the LPG composition in which a predetermined value set in advance is estimated. Is effective in obtaining an appropriate predetermined value.

  Further, based on the fuel pump provided in the fuel delivery line from the fuel tank to the vaporization pressure regulating means, the fuel delivery line pressure detecting means for detecting the pressure of the fuel delivery line, and the detected fuel delivery line pressure The fuel pump operation determining means for determining the operation of the fuel pump and the fuel pump operation control means for controlling the operation of the fuel pump are provided, and the fuel pump operation determining means is preset with the fuel delivery line pressure detected by the fuel pump. When the fuel pump is operated, the fuel pump operation control means is operated to control the fuel delivery line pressure to a predetermined value when the fuel pump is operated. As a means.

  Predetermined as a predetermined value the boundary pressure on whether or not the required engine fuel flow rate can be secured by self-pressure delivery, the pressure of the fuel delivery line is detected to determine the necessity / unnecessity of the fuel pump operation Based on the results, the fuel pump operation control is performed so that the pressure of the fuel delivery line is set to a predetermined value only when self-pressure delivery is insufficient or impossible, so that the engine start at the low temperature and the subsequent engine operation are ensured. It can be stable. In implementing the fifth means, it is necessary to set the predetermined value of the fuel supply line pressure, which is a criterion for determining whether the fuel pump is operating or stopped, to a low value within a range that ensures the engine required maximum fuel flow rate. This is preferable in that the fuel pump is not operated more than necessary while ensuring the fuel supply. The operation control of the fuel pump is preferably performed by duty control by normal PWM, and the detected fuel supply line pressure is compared with a predetermined value to calculate the duty value.

  Furthermore, the first, second, third, fourth, and fifth means are provided with fuel pump bypass means for introducing the liquid LPG in the fuel tank into the fuel delivery line downstream of the fuel pump. It was the sixth means of solution. Preferably, the fuel pump bypass means is provided with a check valve that opens toward the fuel delivery line by a slight pressure difference between the fuel tank and the fuel delivery line in the fuel introduction line connected to the fuel delivery line. The

  When the fuel pump is stopped and the liquid LPG in the fuel tank is sent out by self-pressure, depending on the structure of the fuel pump, there is a fear that the engine required maximum fuel flow rate cannot be supplied due to passage resistance. In such a case, the liquid LPG in the fuel tank is replenished from the fuel introduction pipe, and the engine required maximum fuel flow rate can be supplied.

  According to the present invention, it is possible to accurately and automatically determine the necessity / unnecessity of the fuel pump operation and control the operation, and a necessary and sufficient amount for the required fuel flow rate of the engine without wasting power. The fuel can be supplied reliably, and even when the self-pressure is sent due to the pressure in the fuel tank, the fuel shortage is avoided to ensure the engine start at low temperature and the subsequent engine operation. It can be maintained well.

  An embodiment of the present invention will be described with reference to the drawings. In the layout diagrams of FIGS. 1 to 4 showing different embodiments, an in-tank type fuel pump 5 is installed in a fuel tank 2 storing liquid LPG. The fuel delivery line 7A extending from the discharge port is connected to the vaporizer 4 which is a vapor pressure adjusting means. The fuel delivery line 7A has a fuel cutoff valve 3 that is closed when the engine is stopped and opened during operation. The liquid LPG in the fuel tank 2 passes through the fuel filter 5a and the fuel pump 5 and is sent to the vaporizer 4 by the fuel delivery line 7A. Here, the liquid LPG is vaporized by the engine cooling water or electric resistance heat in addition to this, and at a predetermined positive pressure. The gas LPG is adjusted, introduced into the fuel rail 8 from the fuel supply line 7B, and injected from the fuel injection valve 9 into the intake line.

  The fuel delivery line 7A is connected to a fuel introduction line 11a constituting the fuel pump bypass means 11, and when the pressure in the fuel tank 2 is slightly higher than the pressure in the fuel delivery line 7A, the fuel delivery line 7A. A check valve 11b that opens toward the end is provided in the fuel introduction line 11a. When the fuel pump 5 is operated to forcibly deliver the liquid LPG, the check valve 11b is closed because the fuel delivery line 7A on the discharge side is at a higher pressure than the fuel tank 2. When the fuel pump 5 is stopped and the liquid LPG is sent out by its own pressure, depending on the structure of the fuel pump 5, there may be a passage resistance and the engine required maximum fuel flow rate may not be supplied. In such a case, since the pressure in the fuel tank 2 becomes higher than the pressure in the fuel delivery line 7A, the check valve 11b is opened and the liquid LPG in the fuel tank 2 is supplied to the fuel delivery line 7A. Pressure delivery will be performed without hindrance.

  Further, electronic control devices 10A, 10B, 10C, and 10D are provided in the embodiment shown in FIGS. These have a conventionally well-known function of controlling the fuel injection valve 9 and the ignition timing in accordance with the engine operating state. In addition to these, the operation and stop of the fuel pump 5 necessary for carrying out the present invention are performed. It is assumed that it has a function of performing judgment and its command or operation control of the fuel pump 5.

  On the other hand, in each of the embodiments shown in FIGS. 1 to 3, a return line 15 for returning the liquid LPG exceeding the engine required fuel flow rate in the fuel delivery line 7A to the fuel tank 2 is branched from the fuel delivery line 7A. The pressure regulator 16 is installed in the return line 15. As a result, when the engine required fuel flow rate is small, a large amount of liquid LPG is sent to the vaporizer 4 and an excessive primary pressure acts, and excessive liquid LPG exceeding the vaporization capacity is sent to the vaporizer 4. Is prevented, and the gas LPG having the engine required fuel flow rate can be stably injected from the fuel injection valve 9.

  FIG. 1 shows an embodiment of the first means for solving the problems in the present invention as set forth in claims 1, 5 and 6, wherein a pressure sensor 12 as a fuel tank pressure detecting means is attached to a fuel tank 2. The fuel tank pressure depending on the fuel tank internal pressure, that is, the LPG vapor pressure is detected, and this is input to the electronic control apparatus 10A as fuel tank pressure data. Then, the electronic control unit 10A determines whether or not the self-pressure delivery of the liquid LPG is sufficient for the engine request maximum fuel flow rate in the storage means (ROM), and if it is sufficient, the fuel pump 5 is stopped. A program for determining whether to operate the fuel tank, and a predetermined value of the fuel tank pressure that is a criterion for the determination are preset and stored, and these are fuel pump operation determinations that determine whether the fuel pump 5 is operating or stopped Means.

  That is, the fuel pump operation determination means set in the electronic control device 10A determines the operation / stop of the fuel pump 5 by comparing the fuel tank pressure detected by the pressure sensor 12 with a set predetermined value, When it is determined that operation is necessary, an operation command is issued to the fuel pump 5 to perform operation. In order to minimize the power consumption for driving the fuel pump, it is desirable to set the predetermined value to a low value, for example, a minimum value within a range in which the engine required maximum fuel flow rate is secured.

  The operation of the present embodiment having such a pressure sensor 12 and the electronic control device 10A will be described below. First, when the key switch is turned on, the pressure sensor 12 detects the fuel tank pressure and outputs it to the electronic control unit 10A. Then, the electronic control device 10A compares this with a preset predetermined value to determine whether or not the fuel pump 5 needs to be operated.

  For example, when the fuel tank pressure depending on the vapor pressure of the liquid LPG is lower than a predetermined value at a low temperature, the electronic control unit 10A determines that the forced delivery by the fuel pump 5 is necessary, and starts the operation of the fuel pump 5. By outputting the command, the fuel pump 5 is operated, and the liquid LPG is forcibly delivered toward the vaporizer 4. Then, the input of the fuel tank pressure and the above processing are continuously performed during the engine operation, and thereafter, when the temperature rises and the fuel tank pressure reaches a predetermined value, an operation stop command for the fuel pump 5 is output. Switch to self-pressure delivery only by fuel tank pressure. On the other hand, if the fuel tank pressure is higher than a predetermined value when the key switch is ON, it is determined that the engine required fuel flow rate can be supplied by self-pressure delivery only by the fuel tank pressure, and the operation start command for the fuel pump 5 is not output.

  As described above, the electronic control device 10A has the function of the fuel pump operation determination means and directly detects the fuel tank pressure, so that the necessity / unnecessity of the operation of the fuel pump 5 is accurately and automatically determined. In order to accurately operate the fuel pump 5 only when necessary, it is possible to reliably supply a necessary and sufficient amount of fuel with respect to the fuel flow rate required for the engine while avoiding waste of electric power, so that the cold start and subsequent operation can be performed satisfactorily. Is something that can be done.

  FIG. 2 shows an embodiment of the second means for solving the problems in the present invention as set forth in claims 2, 5 and 7. In place of the pressure sensor 12 in FIG. The temperature sensor 13 is attached. That is, since the fuel tank pressure depending on the vapor pressure of LPG in the fuel tank 2 is correlated with the fuel tank temperature, the fuel tank pressure can be estimated by monitoring the fuel tank temperature. Then, it is determined whether or not the self-pressure delivery of the liquid LPG is sufficient for the engine requested maximum fuel flow rate in the storage means of the electronic control device 10B, and if it is sufficient, the fuel pump 5 is stopped and if not sufficient, the fuel pump 5 is activated. And a predetermined value of the fuel tank temperature which is a criterion for the determination are preset and stored, and these constitute fuel pump operation determining means for determining whether the fuel pump 5 is activated or stopped. ing. In addition, since the vapor pressure varies depending on the LPG composition, the predetermined value in the present embodiment is generally recommended to be set to a high value assuming a low vapor pressure LPG with many butane components.

  In this embodiment including the temperature sensor 13 and the electronic control device 10B, the operation of the fuel pump 5 is performed by comparing the fuel tank temperature detected by the temperature sensor 13 with a predetermined value set in advance. The stop is judged, but its action is substantially the same as the action of the embodiment shown in FIG.

  FIG. 3 shows an embodiment of the third and fourth means for solving the problems in the present invention as set forth in claims 3, 4, 5, 6, 7 and 8, and a pressure sensor 12 as a fuel tank pressure detecting means. A temperature sensor 13 as fuel tank temperature detecting means is attached to the fuel tank 2, and the fuel tank pressure and the fuel tank temperature detected by these are input to the electronic control unit 10C. The electronic control unit 10C determines whether or not the self-pressure delivery of the liquid LPG is sufficient in the storage means for the engine required maximum fuel flow rate, and if it is sufficient, the fuel pump 5 is stopped and if not, the fuel pump 5 is activated. A program to be executed, and predetermined values of the fuel tank pressure and the fuel tank temperature, which are judgment criteria thereof, are preset and stored, and these are the fuel pump operations for judging the operation / stop of the fuel pump 5 The determination means is configured.

  In this embodiment including the pressure sensor 12, the temperature sensor 13 and the electronic control device 10C, the fuel tank pressure detected by the pressure sensor 12 and the fuel tank temperature detected by the temperature sensor 13 are respectively determined. Compared with a predetermined value set in advance, it is determined that the fuel pump 5 is operated when at least one is lower than the predetermined value, and the fuel pump 5 is not operated when both are higher than the predetermined value. Is basically the same as the operation of the embodiment shown in FIGS.

  In the present embodiment, since the pressure and temperature of the fuel tank 2 are detected, the composition of the LPG used can be estimated. Therefore, it is also possible to determine a predetermined value for each of the pressure and temperature for determining whether or not the self-pressure delivery is sufficient according to the estimated LPG composition, that is, for determining whether the fuel pump 5 is activated or stopped. This is easily implemented by providing the electronic control device 10C with an LPG composition calculation function and a predetermined value determination function. Alternatively, for example, a predetermined value for a standard composition LPG is set in advance, and this is corrected according to the LPG composition estimated from the detected fuel tank pressure and fuel tank temperature. A predetermined value for determining stop can also be determined.

  FIG. 4 shows an embodiment of the fifth means for solving the problems described in claims 9 and 10, wherein a pressure sensor 14 as a fuel delivery line pressure detecting means is installed in the fuel delivery line 7A. The fuel delivery line pressure detected by the pressure sensor 14 is input to the electronic control device 10D. The electronic control device 10D has a fuel pump operation determination unit and a fuel pump operation control unit. The fuel pump operation determination means is used to determine whether or not the self-pressure delivery of the liquid LPG is sufficient for the engine required maximum fuel flow rate and if it is sufficient, the fuel pump 5 is stopped and if not sufficient, the fuel pump 5 is activated. A program and a predetermined value set in advance for the fuel delivery line pressure as a criterion for the program are input and stored in the storage means of the electronic control unit 10D. Further, the fuel pump operation control means is a program that controls the operation of the fuel pump 5 so that the fuel delivery line pressure is set in advance to a predetermined value and is stored in the storage means of the electronic control unit 10D. .

  By controlling the operation of the fuel pump 5 so that the fuel delivery line pressure becomes a predetermined value, it is possible to reliably start the engine at a low temperature, and the liquid LPG is excessively delivered due to the increase in the fuel tank pressure accompanying the temperature rise. Thus, the engine operation can be continued stably without causing the inconvenience. When the predetermined value is exceeded, it is determined that the fuel supply by the self-pressure delivery is sufficiently possible, and the fuel pump 5 is stopped. Note that it is preferable to set the predetermined value to a low value within a range in which the engine required maximum fuel flow rate can be secured, in order to prevent the fuel pump 5 from performing more than necessary while ensuring the fuel supply at low temperatures.

  As described above, according to the present invention, only when forced delivery by the fuel pump is required, this is properly operated, and a necessary and sufficient amount of fuel corresponding to the engine required fuel flow rate is obtained while minimizing power consumption. The engine can be sent out to ensure the start of the engine at a low temperature, and the subsequent engine operation can be satisfactorily maintained.

The layout which shows 1st embodiment of this invention. The layout which shows 2nd embodiment of this invention. The layout which shows 3rd embodiment of this invention. The layout which shows 4th Embodiment of this invention.

Explanation of symbols

2 Fuel tank, 4 Vaporizer, 5 Fuel pump, 6 Regulator, 7A Fuel delivery line, 9 Fuel injection valve, 10A, 10B, 10C, 10D Electronic control device, 11 Fuel pump bypass means, 12, 14 Pressure sensor, 13 Temperature sensor, 16 pressure regulator

Claims (12)

In an engine gas LPG supply device that sends liquid LPG in a fuel tank to a vapor pressure adjusting means and injects it as a predetermined positive pressure gas LPG from a fuel injection valve into an intake pipe.
A fuel pump provided in a fuel delivery line from the fuel tank to the vapor pressure adjusting means, a fuel tank pressure detecting means for detecting the pressure of the fuel tank, and an operation determination of the fuel pump based on the detected fuel tank pressure A fuel pump operation determining means for performing
The fuel pump operation determining means is operated when the fuel tank pressure detected by the fuel pump is lower than a predetermined value set in advance, and is stopped when it is high.
A gas LPG supply device for an engine. In an engine gas LPG supply device that sends liquid LPG in a fuel tank to a vapor pressure adjusting means and injects it as a predetermined positive pressure gas LPG from a fuel injection valve into an intake pipe.
A fuel pump provided in a fuel delivery line from the fuel tank to the vapor pressure adjusting means, a fuel tank temperature detecting means for detecting the temperature of the fuel tank, and an operation determination of the fuel pump based on the detected fuel tank temperature A fuel pump operation determining means for performing
The fuel pump operation determination means is operated when the fuel tank temperature detected by the fuel pump is lower than a predetermined value set in advance, and is stopped when it is high.
A gas LPG supply device for an engine. In an engine gas LPG supply device that sends liquid LPG in a fuel tank to a vapor pressure adjusting means and injects it as a predetermined positive pressure gas LPG from a fuel injection valve into an intake pipe.
A fuel pump provided in a fuel delivery line from the fuel tank to the vapor pressure adjusting means, a fuel tank pressure detecting means and a fuel tank temperature detecting means for detecting a pressure and a temperature of the fuel tank, respectively, and a detected fuel tank pressure; And a fuel pump operation determining means for determining the operation of the fuel pump based on the fuel tank temperature,
The fuel pump operation determining means is operated when at least one of the fuel tank pressure and the fuel tank temperature detected by the fuel pump is lower than a predetermined value for each, and is stopped when both are higher.
A gas LPG supply device for an engine. The gas LPG supply device for an engine according to claim 3,
The fuel pump operation determining means estimates the LPG composition based on the detected fuel tank pressure and fuel tank temperature, and determines a predetermined value for each of determining whether the fuel pump is activated or stopped according to the estimated LPG composition. The fuel pump is operated when at least one of the detected fuel tank pressure and fuel tank temperature is lower than a predetermined value determined for each, and is stopped when both are higher.
A gas LPG supply device for an engine.   The engine gas according to claim 1, 2, 3, or 4, wherein a return line for returning a liquid LPG exceeding an engine required fuel flow rate to the fuel tank is provided by branching from the fuel delivery line. LPG supply device.   4. The engine according to claim 1, wherein the predetermined value of the fuel tank pressure, which is a determination criterion for the operation / stop of the fuel pump, is set to a low value within a range in which the engine required maximum fuel flow rate is secured. Gaseous fuel supply device.   The engine gas according to claim 2 or 3, wherein the predetermined value of the fuel tank temperature, which is a determination criterion for the operation / stop of the fuel pump, is set to a high value corresponding to an LPG composition having a low vapor pressure. Fuel supply device.   The predetermined value for each of the fuel tank pressure and the fuel tank temperature for determining the operation / stop of the fuel pump is determined by correcting a predetermined value according to an estimated LPG composition. 4. A gas LPG supply device for an engine according to 4. In an engine gas LPG supply device that sends liquid LPG in a fuel tank to a vapor pressure adjusting means and injects it as a predetermined positive pressure gas LPG from a fuel injection valve into an intake pipe.
Based on a fuel pump provided in a fuel delivery line from the fuel tank to the vapor pressure regulating means, a fuel delivery line pressure detecting means for detecting the pressure of the fuel delivery line, and the detected fuel delivery line pressure Fuel pump operation determining means for determining operation of the fuel pump, and fuel pump operation control means for controlling operation of the fuel pump,
The fuel pump operation determining means is activated when the fuel delivery line pressure detected by the fuel pump is lower than a predetermined value set in advance, and stopped when the fuel pump operation control means is high, and the fuel pump operation control means is activated when the fuel pump is activated. Operation control was performed so that the pipeline pressure was the predetermined value.
A gas LPG supply device for an engine.   10. The engine according to claim 9, wherein the predetermined value of the fuel delivery line pressure, which is a determination criterion for the operation / stop of the fuel pump, is set to a low value within a range in which the engine required maximum fuel flow rate is secured. Gas LPG supply device. The gas LPG supply device for an engine according to any one of claims 1, 2, 3, 4, and 9,
Fuel pump bypass means for introducing the liquid LPG in the fuel tank into the fuel delivery line downstream of the fuel pump;
A gas LPG supply device for an engine. The fuel pump bypass means is connected to the fuel delivery line, and is provided in the fuel introduction line. The fuel pump bypass means is connected to the fuel delivery line by a slight pressure difference between the fuel tank and the fuel delivery line. The engine gas LPG supply device according to claim 11, comprising a check valve that opens toward the engine.

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