JP2000240480A - Method for controlling fuel of lpg engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the discharge of unburned gas by suction of the remaining fuel in a sudden reduction in air quantity by decelerating operation by judging the decelerating operation or not, and stopping the current-carrying to an injector when the decelerating operation is judged. SOLUTION: During the operation of an LPG engine 100 having an LPG regulator 1, a slow lock solenoid valve 2, an injector 3, a venturi part 4, an air-fuel ratio control motor 5 and the like, when it is judged in an engine control computer 7 that the vehicle speed is a prescribed value (for example, 2 km/h) or less from the output of a vehicle sensor, it is judged whether a throttle switch 6 is ON or not. When ON is judged, the current-carrying to the injector 3 is stopped. It is then judged whether the engine rotating speed is larger than the cut rotating speed or not, and when YES is judged, the current-carrying to the slow lock solenoid valve 2 is stopped, and the fuel control processing of the LPG engine is then ended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control method for an LPG engine, and more particularly, to a fuel control method for an LPG engine in which fuel is injected from an injector via a slow lock solenoid valve.

[0002]

2. Description of the Related Art Japanese Unexamined Utility Model Publication No. Sho 61-36163 discloses a technique for closing a slow lock valve during deceleration operation in an LPG engine in which fuel is injected from an injector via a slow lock solenoid valve.

[0003] In the LPG engine disclosed in the above publication, the power supply to the injector is stopped only in conjunction with the case where power supply to the slow lock solenoid valve is stopped during deceleration operation.

Referring to FIG. 3, a flowchart of a conventional fuel control method for an LPG engine will be described. First, it is determined whether the vehicle speed SPD is equal to or less than a predetermined value X (S3).
01). The predetermined value X is, for example, 2 km / h. When it is determined that the vehicle speed SPD is equal to or less than the predetermined value X, it is determined whether or not the throttle switch IDL_SW is on (S302). Throttle switch IDL_SW
Is turned on, the engine speed NE
It is determined whether 1 is larger than the cut rotation speed tNCUT (S303). When it is determined that the engine speed NE1 is higher than the cut speed tNCUT, the energization of the slow lock solenoid valve is stopped (S304).
The power supply to the injector is stopped (S305). Then L
The process of the fuel control of the PG engine ends.

When it is determined that the vehicle speed SPD is not lower than the predetermined value X (NO in S301), the throttle switch I
When it is determined that the DL_SW is not on (N in S302)
O), or the engine speed NE1 is equal to the cut speed tN.
When it is determined that it is not larger than CUT (N in S303)
In O), the slow lock solenoid valve is energized (S
306), the injector is energized (S307). Thereafter, the process of fuel control of the LPG engine ends.

As described above, in the conventional LPG engine fuel control method, the energization of the injector is stopped (S305) only in conjunction with stopping the energization of the slow lock solenoid valve (S304).

[0007]

However, in the above-mentioned conventional fuel control method for the LPG engine, the throttle switch I is set to the deceleration operation state (when the vehicle speed SPD is less than the predetermined value X and the throttle switch I
DL_SW is ON) and the engine speed NE
Unless 1 is larger than the cut rotation speed tNCUT, the energization of the slow lock solenoid valve is not stopped. Therefore, even in the decelerating operation state (the vehicle speed SPD is equal to or lower than the predetermined value X and the throttle switch IDL_SW is turned on), if the engine speed NE1 is not higher than the cut speed tNCUT, the slow lock solenoid valve is energized. Is not stopped.

In a deceleration operation in which the slow lock solenoid valve is energized, fuel is injected from the injector section into the intake pipe, and at the same time, fuel remaining in the venturi section or the intake pipe flows into the combustion chamber at a stretch. Therefore, there is a problem that a large amount of unburned gas is generated in the combustion chamber. The above problem is particularly remarkable when cold evaporation is insufficient. The present invention has been made to solve such a problem.

An object of the present invention is to suppress the discharge of unburned gas due to the suction of residual fuel when the amount of air suddenly decreases due to deceleration operation.

[0010]

According to the present invention, there is provided a fuel control method for an LPG engine, wherein a fuel is supplied to a manifold by a negative pressure generated in a venturi section through a slow lock solenoid valve provided in an LPG regulator. A first path for determining whether a deceleration operation is performed or not, comprising: a path and a second path for supplying the fuel to the manifold via the slow lock solenoid valve and the injector. , The first
If it is determined in step that the operation is decelerating, a second step of stopping the power supply to the injector is included, whereby the object is achieved.

The method of controlling the LPG engine includes a third step of judging whether or not the engine speed is higher than a cut speed after the execution of the second step. If it is determined that the rotation speed is higher than the cut rotation speed, a fourth step of stopping the energization of the slow lock solenoid valve may be further included.

[0012] The first step may include a step of determining whether or not the vehicle speed is equal to or lower than a predetermined value, and a step of determining whether or not an idle switch is on.

[0013]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of an LPG engine 100 according to the present embodiment.

The LPG engine 100 includes an LPG regulator 1, a slow lock solenoid valve 2, an injector 3, a venturi section 4, and an air-fuel ratio control motor 5.
, A throttle switch 6, an engine control computer 7, and an intake manifold 8.

The LPG engine 100 includes a first passage 9 for supplying fuel to the intake manifold 8 by a negative pressure generated in the venturi section 4 through a slow lock solenoid valve 2 provided in the LPG regulator 1, and a slow lock solenoid valve. The fuel supply system further includes a second path 10 for supplying fuel to the intake manifold 8 via the injector 2 and the injector 3.

The slow lock solenoid valve 2 and the injector 3 are electrically connected to an engine control computer 7. Slow lock solenoid valve 2
The operation of the injector 3 is controlled based on a signal from the engine control computer 7.

An input signal from a vehicle speed sensor (not shown) and a signal from the throttle switch 6 are input to the engine control computer 7. The engine control computer 7 is configured to output a signal based on an input signal from the vehicle speed sensor and a signal from the throttle switch
It is determined whether the vehicle is in the deceleration operation or not.

FIG. 2 shows a flowchart of a fuel control method for an LPG engine according to the present embodiment. A fuel control method for an LPG engine according to the present embodiment will be described with reference to FIGS.

The engine control computer 7 includes:
It is determined whether or not the vehicle speed SPD is equal to or less than a predetermined value X based on an input from a vehicle speed sensor (not shown) (S2).
01). The predetermined value X is, for example, 2 km / h. If it is determined that the vehicle speed SPD is equal to or less than the predetermined value X, the engine control computer 7 determines whether the throttle switch 6 is on (S202). If it is determined that the throttle switch 6 is ON, the engine control computer 7 stops the power supply to the injector 3 (S203), and stops executing the I / B (S204).

The engine control computer 7 includes:
It is determined whether or not the engine speed NE1 is higher than the cut speed tNCUT (S205). When it is determined that the engine speed NE1 is higher than the cut speed tNCUT, the engine control computer 7 stops energizing the slow lock solenoid valve 2 (S2).
06). Thereafter, the process of fuel control of the LPG engine ends.

When it is determined that the vehicle speed SPD is not lower than the predetermined value X (NO in S201), or when it is determined that the throttle switch 6 is not turned on (NO in S202).
Then, the engine control computer 7 energizes the injector 3 (S207).

When the injector 3 is energized (S20
7) or the engine speed NE1 is equal to the cut speed tN
If it is determined that it is not larger than CUT (N in S205)
In O), the engine control computer 7 energizes the slow lock solenoid valve 2 (S208).
Thereafter, the process of fuel control of the LPG engine ends.

As described above, according to the fuel control method for the LPG engine according to the present embodiment, during deceleration operation (when the vehicle speed SPD is equal to or less than the predetermined value X (YES in S201), and the throttle switch 6 is turned on (S202). Is YES)), the energization of the injector 3 is always stopped (S20).
3).

Accordingly, the power supply to the injector 3 is not stopped only in conjunction with stopping the power supply to the slow lock solenoid valve 2 during the deceleration operation, but the power supply to the injector 3 is always stopped during the deceleration operation.

That is, even if the slow lock solenoid valve 2 is energized because the engine speed NE1 is not higher than the cut speed tNCUT, the energization of the injector 3 is always stopped during the deceleration operation.

As a result, even when a shortage of vaporization occurs in the cold state during the deceleration operation, it is possible to suppress the discharge of the unburned gas due to the suction of the residual fuel when the amount of air suddenly decreases.

[0027]

As described above, according to the present invention, it is possible to suppress the discharge of unburned gas due to the suction of residual fuel when the amount of air suddenly decreases due to deceleration operation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an LPG engine according to an embodiment.

FIG. 2 is a flowchart of a fuel control method for an LPG engine according to the present embodiment.

FIG. 3 is a flowchart of a conventional fuel control method for an LPG engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LPG regulator 2 Slow lock solenoid valve 3 Injector 4 Venturi part 5 Air-fuel ratio control motor 6 Throttle switch 7 Engine control computer 9 1st path 10 2nd path 100 LPG engine

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02M 21/02 301 F02M 21/02 301R

Claims (3)

[Claims] 1. A first path for supplying fuel to a manifold by a negative pressure generated in a venturi section through a slow lock solenoid valve provided in an LPG regulator, and the fuel through a slow lock solenoid valve and an injector. Control method for an LPG engine including a second path for supplying the pressure to the manifold, wherein a first step of determining whether or not a deceleration operation is performed; and A second step of stopping energization of the injector. 2. The method of controlling the LPG engine, comprising: determining whether the engine speed is higher than a cut speed after performing the second step; and determining the engine speed in the third step. The method of controlling an LPG engine according to claim 1, further comprising: a fourth step of stopping energization of the slow lock solenoid valve when the number is determined to be higher than the cut rotation number. 3. The method according to claim 1, wherein the first step includes a step of determining whether a vehicle speed is equal to or lower than a predetermined value, and a step of determining whether an idle switch is on. Control method of LPG engine.