JP2008121645A - Engine lpg fuel supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure a preferable low-temperature start performance of the engine in an LPG fuel supply device for an engine utilizing the heat of an electric heater in addition to the utilization of the heat of engine cooling water for heating the vaporization of an LPG fuel. <P>SOLUTION: The LPG fuel supply device for an engine comprising a heating vaporization means 3 for heating vaporization of an LPG using an electric heater 31 in addition to the heat of engine cooling water circulating through engine cooling water circulation paths 8a, 8b is provided with a shut-off valve 15 and a temperature sensor 13 as a cooling water temperature sensing means in the engine cooling water circulation path 8a so that a circulation of the engine cooling water to the heating vaporization means 3 is stopped at the time of the low-temperature start of the engine by keeping the shut-off valve 15 in a closed state by an electronic control unit 10A from the start of the power supply to the electric heater 31 until the engine cooling water temperature reaches to a preset temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus for supplying vaporized gas obtained by vaporizing liquefied gas fuel such as LPG (liquefied petroleum gas) under reduced pressure to an engine, and in particular, heat of engine cooling water as heating and vaporizing means for LPG fuel. The present invention relates to an LPG fuel supply device that improves the operability of an engine during a period from a low temperature start to a warm-up operation by using both the heat of an electric heater and the electric heater.

  LPG fuel used as fuel for automobiles and the like has been widely used as fuel for spark ignition engines, and as described in Japanese Patent Laid-Open No. 6-17709, LPG is vaporized under reduced pressure to obtain a predetermined pressure. A method of adjusting to the vaporized gas and injecting it into the intake pipe of the engine is widely used.

  In the method of adjusting the vaporized gas to a predetermined positive pressure as described above, it is common to use the heat of engine cooling water as means for heating and vaporizing the LPG fuel. However, the heating and vaporizing means that uses the heat of engine cooling water tends to cause insufficient fuel vaporization because the cooling water is low temperature when the engine is cold. There is a problem of letting you.

  Therefore, for example, as described in Japanese Utility Model Publication No. 56-41147, in addition to utilizing the heat of engine cooling water, an electric heater is disposed upstream of the vaporizer to sufficiently supply fuel even at a low temperature of the cooling water. A device that can be vaporized has been proposed. Further, Japanese Patent Laid-Open No. 5-223014 discloses the coolant temperature detected by the temperature sensor 13 by the electronic control unit 10B as in the fuel supply system shown in the layout diagram of FIG. It has also been proposed that the end of warm-up is determined from the rise or the like, and the power supply to the electric heater 31 attached to the heating vaporization means 3 is automatically stopped.

However, in the case of using the heat of these electric heaters supplementarily, the circulating water acts in a direction that cancels the effect of the electric heater while the engine cooling water is at a low temperature. There is a problem that the engine operation is not performed properly without vaporization.
JP-A-6-17709 Japanese Utility Model Publication No. 56-41147 Japanese Patent Laid-Open No. 5-223014

  The present invention is intended to solve the above problems, and relates to an LPG fuel supply device for an engine that uses the heat of an electric heater in addition to using the heat of engine cooling water for heating and vaporizing the LPG fuel. It is an object of the present invention to ensure good engine low-temperature starting performance.

  Accordingly, the present invention provides an LPG fuel supply apparatus for an engine having a heating and vaporizing means for heating and vaporizing LPG fuel in combination with an electric heater provided separately from the heat of engine cooling water circulating in the engine cooling water circulation path. The engine cooling water circulation path is provided with a shut-off valve that opens and closes by a control device based on a detection signal from a cooling water temperature detection means provided in the engine cooling water circulation path. From the start until the engine coolant temperature reaches a preset temperature, the shut-off valve is closed, and the circulation of the engine coolant to the heating and vaporizing means is stopped.

  In this way, by providing a shut-off valve in the engine coolant circulation path and controlling the shut-off valve so as to stop the engine coolant circulation until the engine coolant temperature reaches a preset temperature, the low-temperature engine cooling It can avoid that water inhibits the heating action of an electric heater.

  In this case, the engine cooling water temperature detecting means is a temperature sensor and the control means is an electronic control means, and the electronic control means detecting the engine cooling water temperature with the temperature sensor is used as a timing for opening / closing the shut-off valve. If the engine cooling water circulation is controlled while judging the above, the above-described operation can be performed reliably, or the engine cooling water temperature detecting means and the control means can also serve as a single thermo switch. If the shut-off valve is opened and closed by the operation of a thermo switch that detects the temperature of the temperature, it can be implemented at a relatively low cost.

  Thus, according to the present invention, in which the circulation of the engine coolant is stopped until the engine coolant temperature reaches a preset temperature, it is possible to avoid that the low-temperature engine coolant interferes with the heating action of the electric heater, Good engine cold start performance can be secured.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a layout view of an engine fuel supply system including an LPG fuel supply apparatus according to the present embodiment, and a fuel supply pipe connected to a fuel tank 1 in which LPG fuel is stored in a liquid state. The passage 9A is connected to a heating vaporization means (vaporizer) 3 including a hot water heating unit 3a, an electric heating unit 3b having an electric heater and a pressure adjusting unit 3c having a pressure adjusting valve.

  The heating vaporization means 3 adjusts the LPG fuel from a liquid state to a vaporized gas having a predetermined positive pressure by depressurizing and vaporizing the LPG fuel. The heating water heating unit 3a using the engine cooling water as a heat source and the electric heater 31 are used as the heat source. And an electric heating unit 3b used for the control, and a pressure regulating unit 3c is attached downstream thereof. A fuel supply line 9 </ b> B extending from the heating and vaporizing means 3 is connected to an injector 5 installed in the intake line 4 b of the engine 4.

  The hot water heating unit 3a that uses engine cooling water as a heat source has the same configuration as that of a commonly used vaporizer, and is connected to a cooling water jacket 4a provided in the engine 4 by cooling water circulation paths 8a and 8b. Then, the engine coolant is circulated, and the LPG fuel is heated and vaporized by the heat. In view of the configuration of the present embodiment, an electromagnetic shut-off valve 15 is disposed in the cooling water circulation path 8a on the fuel delivery side, and the electronic control unit 10A controls the opening and closing thereof. It has become a characteristic part.

  In addition, the electric heating unit 3b provided on the downstream side of the hot water heating unit 3a is for storing an electric heater 31 such as a flat plate-like PTC heater and exchanging heat with the LPG. It is electrically connected to the control unit 10A and its operation is controlled.

  On the other hand, in the electronic control unit 10A, a general engine control program is installed in the storage means. In addition to the normal fuel injection control function, the engine operation from the ignition key ON to the end of the warm-up operation is performed. In the initial stage, the necessity of the auxiliary heating by the electric heating unit 3b is determined in detail based on various data representing the engine operating state including the engine coolant temperature, and the operation is controlled.

  The engine cooling water temperature is sequentially detected by the electronic control unit 10A based on a detection signal from the temperature sensor 13 disposed on the base end side of the cooling water circulation path 8a on the delivery side. When the detected coolant temperature is lower than a predetermined temperature, the electronic control unit 10A closes the shutoff valve 15 provided in the engine coolant circulation path 8a by a command signal so as to stop the circulation of the engine coolant. This point is a control feature of the present embodiment.

  Next, the operation of the LPG fuel supply apparatus according to the present embodiment will be described in detail using the graphs representing the respective waveform diagrams of FIG.

  First, when the ignition key is turned on when the engine 4 is started, the electronic control unit 10A determines whether or not the engine cooling water temperature detected by the temperature sensor 13 has reached the heater operation reference water temperature. The electric heater energization signal is turned on to energize the electric heater 31.

  In this case, in the conventional example shown in FIG. 3, since the engine cooling water starts to circulate at this point, the heating operation of the LPG by energization of the electric heater 31 is hindered when the cooling water temperature is excessively low. It was. On the other hand, in the present embodiment, while the engine coolant temperature detected by the electronic control unit 10A does not reach the preset shut-off valve opening / closing reference water temperature, the shut-off valve 15 is maintained in the closed state. The control for stopping the circulation of the cooling water is executed.

  For this reason, when the engine is started with the ignition key set to START, the fuel gas electrically heated and vaporized by the electric heating unit 3b is supplied to the engine to achieve a good start, and then the detected engine cooling. When the water temperature reaches the shut-off valve opening / closing reference water temperature, the electronic control unit 10A opens the shut-off valve 15 and starts circulation of the engine coolant to the warm water heating unit 3a.

  Then, the engine is warmed up as time passes, and when the detected engine cooling water temperature reaches a predetermined heater operation reference water temperature, the electronic control unit 10A stops the heater energization signal to the electric heating unit 3b, Thereafter, the LPG fuel is heated and vaporized only by the hot water heating unit 3a.

  As described above, when the heating operation of the LPG fuel by the electric heating unit 3b is obstructed by circulating the engine cooling water at a low temperature, the electronic control unit 10A closes the shut-off valve 15 to close the engine cooling water. Therefore, the LPG is sufficiently heated and vaporized when the engine is started at a low temperature.

  In the present embodiment, the case where the engine coolant temperature detecting means is the temperature sensor and the control means is the electronic control unit 10 has been described. However, in addition to this, a thermostat for turning the switch ON / OFF based on a predetermined temperature is used. Even if a switch is provided to serve as both engine cooling water temperature detection means and shut-off valve control means, the present invention can be implemented in the same manner as described above.

  In this case, it is only necessary to add a thermo switch at a location where the coolant temperature can be detected with respect to the conventional fuel supply device of the engine and connect it so that the shut-off valve 15 can be driven. It can be implemented at a relatively low cost without the need to change or add a unit control program.

  As described above, the engine LPG fuel supply apparatus that uses the heat of the electric heater in addition to the heat of the engine cooling water for heating and vaporizing the LPG fuel, the low temperature start performance of the engine according to the present invention. Can be improved.

The layout which shows embodiment of this invention. The wave form diagram of each signal at the time of the low temperature start in embodiment of FIG. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank, 3 Heating vaporization means, 3a Hot water heating part, 3b Electric heating part, 3c Pressure regulation part, 4 Engine, 9A, 9B Fuel supply line, 10A Electronic control unit, 13 Temperature sensor, 15 Shut-off valve, 31 Electricity heater

Claims (3)

  In an engine LPG fuel supply apparatus having a heating and vaporizing means for heating and vaporizing LPG fuel in combination with an electric heater provided separately from the heat of engine cooling water circulating in the engine cooling water circulation path, the engine cooling water circulation path includes A shut-off valve that is opened and closed by a control device based on a detection signal from a cooling water temperature detecting means provided in the engine cooling water circulation path is provided. Until the temperature reaches a preset temperature, the shutoff valve is closed, and the circulation of engine cooling water to the heating and vaporizing means is stopped.   The engine cooling water temperature detecting means is a temperature sensor and the control means is an electronic control means, and the engine cooling water temperature detected by the temperature sensor is opened and closed by the electronic control means as the control means. 2. The engine LPG fuel supply device according to claim 1, wherein circulation of engine cooling water is controlled while determining timing. 2. The engine cooling water temperature detecting means and the control means are combined with one thermo switch, and the shut-off valve is opened and closed by operating the thermo switch that detects a predetermined temperature. Engine LPG fuel supply device.

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