JPH06239150A - Preheating device - Google Patents

Abstract

PURPOSE:To enhance both the drivability and the startabilty at low temperature of an engine by accelerating the vaporization of fuel for a vehicle using liquefied gas (LPG). CONSTITUTION:A fuel feed pipe 17 is provided, which feeds LPG to a regulator 6from a fuel tank 1 or a heater 11 is provided for the regulator 6, electric power to the heater 11 from a battery 10 is controlled to be fed/cut off based on intake air pressure P (mmHg) and cooling water temperature TW ( deg.C) detected by the detectors 8 and 16 of an ECU 9. By this constitution, electric power is applied to the heater 11 only when the loading of an internal combustion engine 14 is great, and the temperature of the internal combustion engine 14 is low at the time other than a case as mentioned above, a power source is cut off, so that the battery 10 is thereby prevented from being consumed.

Description

Detailed Description of the Invention

[0001]

The present invention relates to liquefied petroleum gas (LP
In a vehicle using G) as fuel, the present invention relates to a preheating device for preheating LPG as fuel.

[0002]

2. Description of the Related Art Conventionally, in a vehicle that uses liquefied petroleum gas (LPG) as a fuel, a fuel supply pipe between a fuel tank and a regulator is provided in order to accelerate vaporization of the fuel and improve power performance of the engine in cold weather. A preheating device that circulates engine cooling water to preheat fuel is used.

[0003]

With the above-mentioned preheating device, LP
When G is preheated, when the engine is started at a low temperature, the engine cooling water is also at a low temperature, therefore preheating is not properly performed, and the startability of the engine cannot be improved. In addition, since the engine cooling water is used to preheat the fuel, it takes time to reach the optimum temperature and it is difficult to adjust it. It is difficult to fine-tune the preheating temperature of the fuel according to the fuel flow rate and always maintain the optimum temperature. Is.

The object of the present invention is to solve the above problems and to provide an LP
It is an object of the present invention to provide an LPG preheating device capable of improving the engine startability in a vehicle using G as fuel and improving the power performance of the engine when cold.

[0005]

DISCLOSURE OF THE INVENTION According to the present invention, heating means provided in a regulator for vaporizing liquefied petroleum gas or a supply pipe for supplying liquefied petroleum gas to the regulator, and supply / interruption of electric power to the heating means. It is a preheating device characterized by including control means for controlling.

Further, the present invention is characterized in that the control means controls the supply / interruption of electric power based on the intake pressure of the engine and the cooling water temperature.

Further, the present invention is characterized in that the control means duty-controls the supply / interruption of electric power based on the intake pressure of the engine.

Furthermore, the present invention is characterized in that the control means duty-controls the supply / interruption of electric power based on the intake pressure of the engine and the cooling water temperature.

[0009]

According to the present invention, the heating means is provided in the supply pipe for supplying the liquefied petroleum gas from the fuel tank to the regulator or the regulator for vaporizing the liquefied petroleum gas supplied.
The control means controls the supply / interruption of electric power to the heating means. As described above, in the present invention, the liquefied petroleum gas is heated by the electrically controlled heating means and supplied to the regulator. Therefore, it is possible to realize the optimum preheating temperature even when the engine is at a low temperature.

Further, since the control means controls the supply / interruption of electric power based on the intake pressure of the engine and the temperature of the cooling water, it is possible to heat the liquefied petroleum gas in accordance with the load of the engine and the temperatures of the engine and the regulator. Therefore, when the engine becomes hot and the liquefied petroleum gas is no longer required to be heated, the power supply can be cut off to save the power consumption.

Further, since the control means duty-controls the supply / interruption of the electric power based on the intake pressure of the engine, the heating means can be controlled to a more suitable temperature according to the load of the engine, and the heating is stable and stable. Liquefied petroleum gas can be promoted to vaporize.

Furthermore, the control means duty-controls the supply / interruption of electric power based on the intake pressure of the engine and the cooling water temperature. Therefore, the heating means can be controlled to an appropriate temperature according to the load on the engine, and the supply / interruption of electric power to the heating means can be controlled according to the temperature of the cooling water of the engine. It can be performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a preheating device 2 which is an embodiment of the present invention.
FIG. 3 is a block diagram showing a configuration of a fuel supply system including 0.
Liquefied petroleum gas (LPG) supplied from the fuel tank 1 passes through the fuel supply pipe 17 in a liquid state and is vaporized under reduced pressure in the regulator 6. The regulator 6 vaporizes the LPG to maintain it at a constant pressure, and adjusts the vaporization amount according to the increase or decrease of the engine load.

The preheating device 20 of the present invention is provided in the fuel supply pipe 17 between the fuel tank 1 and the regulator 6 or in the regulator 6. The internal temperature of the internal combustion engine 14 that uses LPG as fuel is low, and the internal combustion engine 14 and the fuel supply pipe 1
When the temperature of 7 is low, the fuel is less likely to be vaporized as compared with an internal combustion engine that uses gasoline as a fuel, so that the starting is not easy and a long cranking time (a time for rotating the starter motor) is required. Further, immediately after the start, when the no-load high-speed rotation (racing) is performed when the temperature of the cooling water is low, vaporization of LPG due to pressure reduction in the regulator 6 is promoted, and L
The heat of vaporization of PG may cause the regulator 6 to freeze and damage the regulator 6. Therefore, by providing the heater 11 as a heating means between the fuel tank 1 and the regulator 6, the internal combustion engine 14 can be easily started, and the energization time of the heater 11 can be changed according to the increase or decrease of the throttle opening and the engine load. By performing time-division control, freezing of the regulator 6 can be prevented while saving battery consumption.

The preheating device 20 includes a heater 11 arranged around the outer circumference of the fuel supply pipe 17, and an intake pressure P, for example.
(MmHg), cooling water temperature TW (° C), and the like, an electric control unit (ECU) 9 for driving the heater 11 in a time division manner, the heater 11 and the ECU 9
And a battery 10 for supplying electric power to.

Further, the fuel air introduced from the intake port 2 is purified by the air cleaner 3, the amount of inflow is adjusted by the throttle valve 5, and reaches the venturi 7 via the intake pipe 4. The inflow velocity of the combustion air is accelerated by the venturi 7 having a narrowed cross section of the intake pipe 4, and the LPG vaporized by the regulator 6 is attracted to the intake pipe 4 from the fuel supply passage 17 having an open end in the venturi 7. In the intake pipe 4 near the venturi 7, the vaporized LPG introduced according to the opening degree of the throttle valve 5 and the combustion air that is accelerated by the venturi 7 and forms a vortex of the air are mixed, and the internal pressure becomes negative pressure, and cooling is performed. It is introduced into a cylinder of an internal combustion engine 14 covered by a water jacket. The air-fuel mixture is compressed by the piston 18 to an appropriate compression ratio. At this time, the spark plug 12 ignites, and the air-fuel mixture trapped in the cylinder is ignited. The burned air-fuel mixture is discharged to the outside through the exhaust pipe 13.

Further, the detector 8 detects the intake pressure P (mmHg) of the combustion air sucked into the intake pipe 4, and the detector 16 detects the water temperature TW (° C) of the cooling water 17.

FIG. 2 is a graph showing the relationship between the cooling water temperature TW and the intake pressure P for explaining the operation of the heater 11 of the preheating device 20, and FIG. 3 is a flow chart for explaining the operation of the heater 11. FIG. 4 is a timing chart showing an example of the operation of the heater 11. As shown in FIG.
In the preheating device 20, the intake pressure P (mmHg) is equal to or higher than a predetermined intake pressure PO (mmHg), and the cooling water temperature TW.
When the temperature (° C) is equal to or lower than the predetermined cooling water temperature TWM (° C), the heater 11 is turned on and the LPG as fuel is used.
Preheat (liquefied petroleum gas). In other cases, the heater 11 is turned off to reduce the consumption of the battery 10 by the heater 11. That is, the fuel is preheated only at a low temperature and a high load, and when the preheating is unnecessary, the heater 11 is turned off to reduce the consumption of the battery 10.

As shown in FIG. 3, in the preheating device 20, the intake pressure P (mmHg) and the cooling water temperature TW (°
C) is detected. In step i2, the intake pressure P (mmHg) detected in step i1 is the predetermined intake pressure PO.
(MmHg) or more is determined, and PO ≦ P
If so, the process proceeds to step i3. If PO> P, the process proceeds to step i4. At step i3, the cooling water temperature TW (°
C) is below a predetermined cooling water temperature TWM (° C), and if TW ≤ TWM, step i5
Move to step i4, if TW> TWM. In step i4. The heater 11 is turned off, and the process proceeds to step i1. In step i5, the heater 11 is turned on, and the process returns to step i1. In this way, the intake pressure P and the cooling water temperature TW are repeatedly detected at regular intervals, and the conduction state of the heater 11 is switched based on these detected values to control the fuel preheating.

For example, as shown in FIG. 4, an engine having a low temperature is started at time t0, and each time t0, ..., T.
If the intake pressure P and the cooling water temperature TW are detected at n, ..., At any time from t0 to t4, the intake pressure P and the cooling water temperature TW detected at step i1 in FIG.
(Low load) and TW ≦ TWM (low temperature), during which the heater 11 is in the OFF state. At times t5 and t6, for example, the accelerator is stepped on for starting, and the intake pressure detected at times t5 and t6 is PO ≦ P (high load).
The cooling water temperature TW is in the state of TW ≦ TWM (low temperature). During this time, the heater 11 is in the ON state. Again, at time t7, the engine, that is, the cooling water temperature is low (T
W ≦ TWM), the accelerator is loosened (low load), and the heater 11 is turned off.

Similarly, at times t8, t11, ..., Tn-1, PO≤P (high load) and the cooling water temperature TW≤TWM.
(Low temperature) is detected, the heater 11 is turned on, and PO> P at times t9, t10, t12, ..., Tn.
(Low load), cooling water temperature TW ≤ TWM (low temperature) is detected, and the heater 11 is turned off. In this way
After a while after the engine is started, if the engine is warmed by the operation of the engine and the cooling water temperature TW is always equal to or higher than the predetermined cooling water temperature TWM (° C), the heater 11 turns off.
The FF state is set.

As described above, according to this embodiment, the preheating device 2
Since 0 has the heater 11 driven by the battery 10, it reaches the appropriate preheating temperature in a relatively short time, and the warm-up operation immediately after the start can be stably maintained even when the engine is started at a low temperature. Further, based on the detected intake pressure P (mmHg), the fuel can be preheated at any time when the engine is under high load, and therefore, the power performance of the engine such as the throttle response at low temperature can be improved. You can Further, when the engine is at a high temperature where the fuel preheating is unnecessary, that is, when the cooling water temperature TW (° C) is TWM ≦ TW, the heater 11 can be turned off to save the consumption of the battery 10. Therefore, the fuel can be preheated efficiently.

FIG. 5 shows a preheating device 2 according to another embodiment of the present invention.
6 is a timing chart for explaining the operation of the heater 11 of No. 0. As shown in FIG. 5, the heater 11 has a predetermined time T (msec) as one cycle, and T (msec)
The heater 11 is turned on for x (msec) of
During (T−x) (msec), the heater 11 is turned off and time-division driving is performed.

FIG. 6 is a graph showing the duty ratio m (%) for driving the heater 11 of the preheating device 20 in a time division manner. Time for turning on the heater 11 x (mse
c) is the intake pressure T (mmHg) given from the detector 8.
Based on the above, the duty ratio obtained from the graph shown in FIG. 6 is m (%), and x = mT / 100 (msec) (1) As the duty ratio m, as shown in FIG. 3, a constant intake pressure PO (mm
When it is equal to or less than Hg), a constant level of duty ratio m0 is given and a certain amount of preheating is performed even when the throttle valve 5 is fully closed. Further, when the intake pressure P becomes equal to or higher than the predetermined intake pressure PM (mmHg), the duty ratio 10
0% is given, and the intake pressure P (m
heater 11 until mHg) falls below PM (mmHg)
Is kept ON.

FIG. 7 is a flow chart for explaining the operation of the preheating device 20 which is another embodiment of the present invention.
This flowchart starts when the engine is started. In step k1, the detector 8 detects the intake pressure P. At step k2, the duty ratio m is calculated as a percentage by interpolation from the graph shown in FIG. 6 based on the intake pressure P detected at step k1. At step k3, the time x (msec) for holding the heater 11 in the ON state is
It is calculated and calculated from the mathematical expression (1).

At step k4, the current time y is detected. At step k5, the heater 11 is turned on and this state is maintained. At step k6, the heater 11 is turned on.
Calculate the time A at which the FF state is set, that is, A = y + x,
Set. At step k7, the current time y is obtained, and at step k8, it is determined whether or not the current time y reaches the time A at which the heater 11 is turned off. When the current time y does not reach the time A when the heater 11 is turned off, the process returns to step k7 and the current time y is detected again.

When the current time y reaches the time A at which the heater 11 is turned off, the process moves to step k9 and the heater 11 is turned off. Next, at step k10, time B at which the heater 11 is turned on, that is, B =
Calculate and set the time calculated by y + T-x. At step k11, the current time y is detected, and at step k12
Then, it is determined whether or not the current time y reaches the time B at which the heater 11 is turned on. If the current time y does not reach the time B at which the heater 11 is turned on, the process returns to step k7 to detect the current time y again. When the current time y reaches the time B at which the heater 11 is turned on, the process returns to step k1. In this embodiment, steps k1 to
Determination of duty ratio m at step k3 and steps k4 to
The time-divisional driving of the heater 11 in step k12 is performed in one flow, but these may be performed under different controls.

As described above, according to this embodiment, the intake pressure P is PM (mmHg) at a high load with a large fuel flow rate.
The heater 11 is turned on at a duty ratio of 100% only when it takes a value exceeding, and the duty ratio is reduced as the load becomes lighter. As a result, the heat generation of the heater 11 is stabilized, the vaporization of the LPG can be promoted in a stable state even with respect to the load change of the engine, and the duty ratio m is reduced when the load is light, so that the consumption of the battery 10 is saved. You can

FIG. 8 is a graph for giving a correction value according to the cooling water temperature to the duty ratio of the time division drive of the preheating device 20. For the heater 11 of the preheating device 20, the duty ratio m is obtained based on the intake pressure P from the graph shown in FIG. Further, based on the cooling water temperature TW (° C) given from the detector 16, the correction coefficient k is obtained from the graph shown in FIG. 8, and the time x for turning on the heater 11 is given.

X = kmT / 100 (2) As shown in FIG. 8, when the cooling water temperature TW (° C) is equal to or lower than the predetermined temperature TW0 (° C), k = 1 and the duty ratio is set only by the intake pressure P. m shall be determined. Further, the correction coefficient k gradually decreases from 1 as the cooling water temperature TW (° C) becomes higher than TW0 (° C), and when the cooling water temperature TW (° C) exceeds TWM (° C), a constant value is obtained. The duty ratio m is multiplied by the coefficient value of k0 (0 <k0 <1) to determine the duty ratio of the heater 11.

FIG. 9 is a flow chart for explaining the operation of the preheating device 20 which is still another embodiment of the present invention. This flowchart starts when the engine is started. At step j1, the intake pressure P is detected by the detectors 8 and 16.
(MmHg) and the cooling water temperature TW (° C) are detected. At step j2, from the graph shown in FIG.
The duty ratio m is obtained as a percentage by interpolation based on the intake pressure P detected in. Further, the correction coefficient k is obtained by interpolation based on the cooling water temperature TW (° C) detected in step j1 from the graph shown in FIG. At step j3, the time x (mse
c) is calculated by the mathematical expression (2).

At step j4, the current time y is detected. In step j5, the heater 11 is turned on and this state is maintained. At step j6, the heater 11 is turned on.
Calculate the time A at which the FF state is set, that is, A = y + x,
Set. At step j7, the present time y is obtained, and at step j8, it is judged whether or not the present time y reaches the time A at which the heater 11 is turned off. When the current time y does not reach the time A when the heater 11 is turned off, the process returns to step j7 to detect the current time y again.

When the current time y reaches the time A at which the heater 11 is turned off, the process moves to step j9 and the heater 11 is turned off. Next, at step j10, time B at which the heater 11 is turned on, that is, B =
Calculate and set the time calculated by y + T-x. At step j11, the current time y is detected, and at step j12
Then, it is determined whether or not the current time y reaches the time B at which the heater 11 is turned on. If the current time y does not reach the time B at which the heater 11 is turned on, the process returns to step j7 to detect the current time y again. When the current time y reaches the time B at which the heater 11 is turned on, the process returns to step j1. In the present embodiment, the determination of the duty ratio m in steps j1 to j3 and the time-divisional driving of the heater 11 in steps j4 to j12 are performed under one control, but these may be controlled separately. You may go with.

As described above, according to the present embodiment, the preheating device 20 drives the heater 11 in a time-divisional manner by the intake pressure P of the engine and the cooling water temperature TW, so that the heat generation of the heater 11 is kept stable and the low temperature and high load is maintained. At times, vaporization of LPG can be promoted in a stable state. Therefore, power performance such as throttle response of the engine at low temperature is improved and L
It is possible to reduce the consumption of the battery 10 after the completion of warming up, which does not require much preheating of the PG.

[0035]

As described above, according to the present invention, in the preheating device, the heating means is provided in the supply pipe for supplying the liquefied petroleum gas from the fuel tank to the regulator or the regulator for vaporizing the liquefied petroleum gas supplied, and the control is performed. The means controls the supply / interruption of power to the heating means. Therefore, this preheating device can electrically control and heat the liquefied petroleum gas and supply it to the regulator, and preheat the liquefied petroleum gas in a shorter time than in the case where the cooling water is circulated to preheat the liquefied petroleum gas. be able to. Further, the preheating temperature of the liquefied petroleum gas can be finely adjusted to easily maintain the optimum preheating temperature.

Further, since the control means controls the supply / interruption of electric power based on the intake pressure of the engine and the cooling water temperature, the liquefied petroleum gas can be heated according to the load of the engine, and the engine becomes high temperature. When it becomes unnecessary to heat the liquefied petroleum gas, the power supply can be cut off to save power consumption. Therefore, even when the engine temperature is low, vaporized liquefied petroleum gas corresponding to the throttle opening can be supplied, and the power performance of the engine can be improved.

Further, since the control means duty-controls the supply / interruption of electric power based on the intake pressure of the engine, the heating means can be controlled to a more suitable temperature according to the load of the engine, and the heating is stable and stable. The vaporization of liquefied petroleum gas can be promoted.

Further, the control means duty-controls the supply / interruption of electric power based on the intake pressure of the engine and the cooling water temperature, so that the heating means can be controlled to an appropriate temperature according to the load of the engine, and further the engine can be controlled. Since the supply / interruption of electric power to the heating means can be controlled in accordance with the cooling water temperature, the liquefied petroleum gas can be preheated more appropriately.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a fuel supply system including a preheating device 20 according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a cooling water temperature TW (° C) and an intake pressure P (mmHg) for explaining the operation of the preheating device 20.

FIG. 3 is a flowchart for explaining the operation of the preheating device 20.

FIG. 4 is a timing chart showing an example of the operation of the preheating device 20.

FIG. 5 is a timing chart for explaining the operation of the preheating device 20 which is another embodiment of the present invention.

FIG. 6 is a graph showing a duty ratio m for time-divisionally driving the heater 11 of the preheating device 20.

FIG. 7 is a flow chart for explaining the operation of the preheating device 20 which is another embodiment of the present invention.

8 is a graph that gives a correction value according to the cooling water temperature to the duty ratio of the time division drive of the preheating device 20. FIG.

FIG. 9 is a preheating device 20 which is still another embodiment of the present invention.
5 is a flowchart for explaining the operation of FIG.

[Explanation of symbols]

 1 Fuel Tank 2 Intake Port 4 Intake Pipe 5 Throttle Valve 6 Regulator 7 Venturi 8, 16 Detector 9 ECU (Electrical Control Unit) 10 Battery 11 Heater 14 Internal Combustion Engine 15 Cooling Water 17 Fuel Supply Pipe 20 Preheating Device

Claims (4)

[Claims] 1. A heating means provided in a regulator for vaporizing liquefied petroleum gas or a supply pipe for supplying liquefied petroleum gas to the regulator, and a control means for controlling supply / interruption of electric power to the heating means. Preheating device characterized by. 2. The preheating device according to claim 1, wherein the control means controls supply / interruption of electric power based on an intake pressure of the engine and a cooling water temperature. 3. The preheating device according to claim 1, wherein the control means duty-controls the supply / interruption of electric power based on the intake pressure of the engine. 4. The preheating device according to claim 1, wherein the control means duty-controls supply / interruption of electric power based on an intake pressure of the engine and a cooling water temperature.