JPH05223014A - Fuel supply device for lp gas engine - Google Patents

Abstract

PURPOSE:To prevent an engine from malfunctioning due to a rich air-fuel ratio during cold start. CONSTITUTION:A heating plate 8 attached on one side with a PTC heater 9 and on the other side with fins 8a is attached to one side wall 6 of a primary pressure reducing chamber 5 in an LPG regulator 1 through the intermediary of a heat insulation gasket 10, and the PTC heater 9 is energized for heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved fuel supply system for an LP gas engine.

[0002]

2. Description of the Related Art A fuel supply system of this type supplies LPG stored in a cylinder in a liquid state under reduced pressure by an LPG regulator to an engine via an LP gas mixer.

The LP gas regulator is a liquid L
A primary decompression chamber for decompressing P gas and a secondary decompression chamber for decompressing the P gas are provided. A preheater chamber adjacent to the primary decompression chamber and provided upstream of the primary decompression chamber is provided with a hot water passage for passing cooling water of the engine, and the liquid LP gas in the preheater chamber is provided by the engine cooling water. Is heated to promote vaporization of fuel in the primary decompression chamber (see, for example, Japanese Utility Model Laid-Open No. 2-131064).

[0004]

SUMMARY OF THE INVENTION In the above conventional technique,
If you run a standard fuel with a high butane content (that is, it has a high boiling point and is difficult to vaporize) in a cold region and then run without warming up the engine, the temperature of the engine cooling water will be low immediately after the engine starts, and the LPG fuel vaporization heat However, the normal pressure in the primary decompression chamber is not maintained, and the primary decompression chamber is filled with liquid fuel, resulting in engine malfunction due to rich air-fuel ratio (A / F).

Under the above conditions, when the engine is stopped immediately after the engine is started, the liquid fuel filled in the regulator primary decompression chamber is vaporized by the engine cooling water, and 2
A / F is supplied from the next decompression chamber to the engine through the mixer.
Since the engine becomes rich, it becomes difficult to start at the time of restarting, and liquid fuel is temporarily supplied to the engine even after restarting, and the air-fuel ratio becomes excessively rich, causing a problem of engine failure.

[0006] Therefore, an object of the present invention is to provide a fuel supply device capable of solving such a problem.

[0007]

In order to achieve the above object, a fuel supply system for an LP gas engine according to the present invention comprises a PTC.
Attach the heater (9) to one side and the fin (8a) to the other side
The plate to be heated (8) attached with is attached to the side wall (6) of the primary decompression chamber (5) of the LPG regulator (1) via the heat insulating gasket (10) so that the PTC heater (9) is electrically heated. Configured.

Instead of the PTC heater (9), a heater such as a nichrome wire which is heated by energization may be used. Judging from the engine speed signal, the engine cooling water temperature signal, the ignition ON / OFF signal and the starter motor ON / OFF signal, the PTC heater (9) is energized to start the engine warming after the engine is started in the cold state. It is effective to configure so that the energization is stopped after the machine.

In addition, after a lapse of a certain time after the start of energization of the PTC heater (9), the starter motor (23a)
It is effective to be able to energize.

[0010]

By energizing the PTC heater, the LPG regulator is heated before the engine is started, the vaporization of the liquid fuel is promoted, and the starting is facilitated.

Further, in a configuration in which energization of the PTC heater is started after the engine is started in the cold state and energization is stopped after the engine is warmed up, the PT is heated when the starter motor is rotating.
Since the heating power to the C heater is not consumed, the load on the battery at that time does not increase, and there is no fear that the cranking rotation speed will decrease. After warming up, the PTC heater is de-energized to suppress power consumption.

If the starter motor can be energized after a lapse of a certain time after the PTC heater is energized, the starter motor is not energized at the beginning of energization because the consumption current of the PTC heater is large. Since it is possible to prevent the large current at the beginning of energization and the starting current of the starter motor from being simultaneously applied to the battery, there is no fear that the cranking rotation speed will decrease. Further, since the liquid fuel in the LPG regulator is heated by the PTC heater before the starter motor is started and vaporization is promoted, the engine state after starting is more stable.

[0013]

1 to 3, 1 is an LPG regulator, 2 is its body, 3 is a fuel inlet, 4 is a preheater chamber, 5 is a primary decompression chamber, and 6 is a preheater chamber 4. It is formed integrally with the body 2 by the side wall that partitions the primary decompression chamber,
A hot water passage 7 is provided in this to circulate engine cooling water.

Reference numeral 8 is a heated plate with fins provided in the primary decompression chamber 5, and a PTC heater (positive temperature coefficient thermistor) 9 is adhered and fixed to the side opposite to the fins 8a with a conductive adhesive. The heated plate 8 is attached to the side wall 6 of the primary decompression chamber 5 by a screw through a heat insulating gasket 10.

Reference numeral 11 denotes an electrically insulating heat insulating plate provided on the left side of the side wall 6, and 12 denotes one surface of the PTC heater 9 (right surface in the figure).
The spring terminal elastically pressure-contacted with is connected to the positive terminal of the battery 15 by the electric wire 13 via the contact 14a of the relay 14.

The other surface (the surface on the left side of the figure) of the PTC heater 9 is body-grounded by the body 2. Reference numeral 16 is a primary valve arranged between the preheater chamber 4 and the primary decompression chamber 5, 17 is a secondary decompression chamber, 18 is an atmosphere chamber, and 19 is between the primary decompression chamber 5 and the secondary decompression chamber 17. Secondary valve installed,
Reference numeral 20 is a slow lock solenoid valve.

Reference numeral 21 is a fuel tank, and LP is provided in the fuel passage 22.
It communicates with the fuel inlet 3 of the G regulator 1. 23 is an engine, 24 is an intake manifold, 25 is a mixer, 2
Reference numeral 5a is an injector, and the LPG regulator 1 is in communication with the mixer 25 and the injector 25a through LP gas passages 26 and 27. The arrow A indicates the flow of fuel in the LPG regulator 1. Reference numeral 28 denotes a key switch, which is turned on by one step operation and turned on by a two step operation.

In the first embodiment, when the key switch 28 is operated to turn on the ignition, the relay 14 is excited and the PTC heater 9 is energized through its a contact 14a. A large current flows through the PTC heater 9 in the initial period when the PTC heater 9 is cold, and when the temperature of the PTC heater 9 rises, its electrical resistance increases and the current flow decreases.

As described above, by energizing the PTC heater 9, the LPG regulator is heated before the engine is started, the vaporization of the liquid fuel is promoted, and the normal primary pressure is secured.
Does not become rich.

FIG. 4 shows a comparison of the change in the amount of liquid fuel with the lapse of time after the ignition is turned on between the prior art and the first embodiment, and it is understood that the present invention has a small amount of liquid fuel.

FIG. 5 shows the pressure in the primary decompression chamber.
It can be seen that the first embodiment is stable. Further, as shown in FIG. 6, in the first embodiment of the present invention, the A / F is stable and the engine stall does not occur.

Although the PTC heater is used in the first embodiment, other heaters such as nichrome wire may be used instead of the PTC heater. FIG. 7 shows a second embodiment of the present invention.
The components having the same numbers as those in the first embodiment have the same functions.

In the second embodiment of FIG. 7, 29 is a water temperature switch for measuring the engine cooling water temperature, 30 is a rotation speed detector for detecting the engine speed, and 31 is an ECU (control unit).
Then, the engine speed signal from the speed detector 30, the engine cooling water temperature signal from the water temperature switch 29, the ignition ON / OFF signal from the key switch 28, and
Judging from the starter motor ON / OFF signal, the relay 14 is excited to start energizing the PTC heater 9 after the engine is started in the cold state, and after the engine is warmed up, the relay 14 is restored to stop energizing the PTC heater. Control to do.

In the second embodiment, in addition to the effects of the first embodiment, since the load of the PTC heater is not applied to the battery during cranking, the cranking rotation speed is PTC.
There is no fear that the terminal voltage of the battery will drop due to the load of the heater, and it can be started reliably.

Further, after warming up, unnecessary power supply to the PTC heater can be stopped and power consumption can be suppressed. Particularly, the Curie point of the PTC heater after warm-up is lower than the engine cooling water temperature, so that the problem of the first embodiment that the current continues to flow to the PTC heater even after engine warm-up is solved in the second embodiment. It

FIG. 8 shows a third embodiment of the present invention. Reference numeral 32 is a normally closed solenoid valve inserted in the middle of the fuel passage 22. When the key switch 28 is operated to turn on the ignition, the solenoid valve 32 is turned on. The fuel passage 22 is opened.

Further, 33 is a delay circuit connected to the ignition contact of the key switch 28, and 34 and 35.
Is a relay and 23a is a starter motor connected as shown in the figure. In addition, in the third embodiment, the first embodiment,
The components having the same numbers as in the second embodiment have the same functions.

In the third embodiment shown in FIG. 8, when the ignition switch is turned on by operating the key switch 28, the solenoid valve 32 is opened and the fuel tank 2 is fed to the LPG regulator 1.
Liquid fuel is supplied from 1, and at the same time, the relay 14 operates to energize the PTC heater 9.

Then, after a lapse of a fixed time determined by the characteristics of the delay circuit 33, the relay 34 is excited, and the starter motor 23a can be energized. Here, when the key switch 28 is operated to set the starter motor to the ON position, an exciting current flows through the coil of the relay 35 via the contact 34a of the relay 34, and a starting current is supplied to the starter motor 23a via the contact 35a. And cranking starts.

By this time, the fuel of the LPG regulator has been heated by the PTC heater for a certain period of time or more, and the vaporization has been promoted, so that the engine operates stably.
Further, the energized current flow to the PTC heater 9 is large only during the first cold, and becomes smaller as the PTC heater warms up thereafter. Therefore, during cranking, the large current flow of the PTC heater is not simultaneously applied to the battery. Therefore, the cranking rotation speed does not decrease and the starting becomes easy.

Since the starter motor is not turned on until a certain time has elapsed, the starting current of the star motor does not flow, and therefore the terminal voltage of the battery does not drop due to this starting current. However, as shown in FIG. 9, the flow rate can be made larger than in the first embodiment.

Therefore, the temperature rise of the PTC heater is also shown in FIG.
As a result, the vaporization of the fuel is promoted, and the amount of the liquid fuel is reduced as shown in FIG. 11, resulting in a good result.

[0033]

Since the fuel supply device of the present invention is configured as described above, the vaporization of the liquid fuel is promoted by the electric heating to the heater such as the PTC heater and the normal primary pressure is secured, Liquid fuel does not accumulate in the primary decompression chamber. Therefore, the A / F does not become rich, and the A / F is stable when left in the fast idle after cold start, and engine stall does not occur. In addition, it becomes easy to restart when cold. Furthermore, since the pressure of the primary decompression chamber of the LPG regulator is kept constant immediately after the start, the amount of fuel supplied to the mixer is stable, and the engine can be warmed immediately after the start without the need for warming up the engine.

Further, in the inventions of claims 3 and 4, since a large energization current of the PTC heater does not flow during cranking, sufficient electric power is supplied to the starter motor, the cranking rotation speed does not decrease, and the cooling is low. There is no loss of startability.

In the third aspect of the invention, since the PTC heater is automatically de-energized after warming up, the alternator load is reduced, which is useful for improving fuel efficiency. Further, in the invention of claim 4, since the PTC heater is energized for a certain time or more before cranking, the vaporization of the fuel is further promoted and the engine state after starting is more stable.

[Brief description of drawings]

FIG. 1 is a system diagram of a first embodiment of the present invention, in which an LPG regulator is a vertical schematic diagram.

FIG. 2 is a vertical sectional view of the LPG regulator of the embodiment of FIG.

FIG. 3 is a partially enlarged view of FIG.

FIG. 4 is a diagram showing the amount of liquid fuel in the primary decompression chamber in comparison with the prior art and the first embodiment of the present invention.

FIG. 5 is a diagram showing the primary depressurizing chamber pressure.

FIG. 6 is a diagram showing A / F similarly.

FIG. 7 is a system diagram of a second embodiment of the present invention.

FIG. 8 is a system diagram of a third embodiment of the present invention.

FIG. 9 is a flow chart showing a first embodiment of the present invention in which a current is continuously supplied to a PTC heater.
The line diagram shown in comparison with an example and the 3rd example.

FIG. 10 is a diagram showing PTC heater temperature.

FIG. 11 is a diagram showing a liquid fuel amount similarly.

[Explanation of symbols]

 1 LPG regulator 5 Primary decompression chamber 6 Side wall 8 Heated plate 8a Fin 9 PTC heater 10 Insulation gasket 23 Engine 28 Key switch

Claims (4)

[Claims] 1. A primary decompression of an LPG regulator (1) via a heat insulating gasket (10) of a heated plate (8) having a PTC heater (9) mounted on one side and fins (8a) on the other side. A fuel supply device for an LP gas engine, which is attached to a side wall (6) of a chamber (5) and is configured to electrically heat a PTC heater (9). 2. The fuel supply device according to claim 1, wherein a heater heated by energization is used instead of the PTC heater (9). 3. Judging from the engine speed signal, engine cooling water temperature signal, ignition ON / OFF signal and starter motor ON / OFF signal, energization of the PTC heater (9) is started after the engine is started in the cold state. The fuel supply device according to claim 1, wherein the power supply is stopped after the engine is warmed up. 4. The fuel supply device according to claim 1, wherein the starter motor (23a) can be energized after a lapse of a certain time after the PTC heater (9) is energized.