JPS63259147A - Liquefied petroleum-gas feeder for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent shocks at the time of accelerating due to the air-fuel ratio control from being generated in an engine provided with a plurality of fuel systems, in which both a variable opening control valve and a power valve are placed respectively, by controlling a step motor for the variable opening control valves in accordance with a plurality of specified maps. CONSTITUTION:A main fuel port 8 and a power fuel port 9 in a carburettor 2 are connected by means of each of the main and power fuel passages 12, 13 to an LPG regulator 15 respectively. In addition, in the main fuel passage 12 is placed a variable opening control valve 16 operated by a step motor 18, and further, in the power fuel passage 13 is placed a power valve 20 respectively, and at the same time, these are controlled by an ECU 17 respectively. Hereupon, the ECU is provided with the functions of controlling the step motor 18 through adding a correction value to the No.1 map when the power valve 20 is caused to open, and then controlling the step motor 18, through causing the power valve 20 to open, in accordance with the No.2 map.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply system for an internal combustion engine that uses liquefied petroleum gas (LPG) as fuel.

[Conventional technology]

As prior art related to the present invention, Japanese Patent Application Laid-Open No. 61-126
No. 364 and Japanese Unexamined Patent Publication No. 61-207868 are known.

The liquefied petroleum gas fuel supply system for an internal combustion engine disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 61-126364 has two fuel passages formed in parallel, and one of the fuel passages is provided with a fuel supply system based on an electrical signal from a control device. A variable opening control valve whose opening degree is continuously varied by a controlled step motor is disposed. A power valve that is opened and closed by an on/off signal from a control device is arranged in the other fuel passage. The variable opening control valve is controlled to set the air-fuel ratio to a predetermined value depending on the operating conditions of the engine. On the other hand, the power valve is closed during normal operation, but is switched from closed to open during high load and acceleration operation, and the amount of fuel is increased by the amount of fuel passing through the fuel passage that is opened by the power valve. The mixture is corrected to be richer, improving acceleration performance.

Furthermore, the control method for a fuel supply system for an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 61-207868 constantly corrects the air-fuel ratio of the air-fuel mixture by appropriately multiplying it according to intake air temperature, cooling water temperature, acceleration, etc. This is a control method that can be used.

[Problem that the invention seeks to solve]

In a liquefied petroleum gas supply system for an internal combustion engine that has a power valve and a variable opening control valve whose opening is varied by a step motor, the air-fuel ratio is controlled to be lean during light loads when the opening of the throttle valve is small. The air-fuel ratio is controlled to be rich during high loads when the opening is large. Therefore, when the opening degree of the throttle valve exceeds a predetermined opening degree, there is a problem in that the air-fuel ratio changes significantly due to refueling from the power valve, resulting in deterioration of drivability. In other words, the moment the power valve is switched from closed to closed in order to transition from steady operation to accelerated operation, the air-fuel mixture rapidly changes from lean to rich, causing a sudden change in the torque generated by the engine, causing the air-fuel ratio to change. A problem arises in which the shock caused by

The present invention focuses on the above problem, and solves the sudden change in air-fuel ratio when the power valve is switched from closed to open.
An object of the present invention is to provide a liquefied petroleum gas supply device for an internal combustion engine that can prevent shock during acceleration of a vehicle.

[Means for solving problems]

A liquefied petroleum gas supply device for an internal combustion engine according to the present invention that meets this purpose is provided with a variable opening control valve whose opening is continuously varied by a step motor controlled based on an electric signal from an electronic control device. and a second fuel system in which a power valve is disposed that is opened and closed by an on/off signal from the electronic control unit, and when the load is low, the power valve is closed and the power valve is opened and closed. An internal combustion engine that uses liquefied petroleum gas as fuel.The air-fuel ratio is controlled by the fuel supply from the variable-opening control valve, and when the load is high, the air-fuel ratio is controlled by the fuel supplied from both the variable-opening control valve and the power valve. In the electronic control device, when the power valve is switched from closed to open and the opening degree of the throttle valve becomes a predetermined opening degree or more, the first step motor control is applied when the power valve is closed. A function that adds a correction value to the map that increases the step value of the step motor over time, and when the correction value reaches a predetermined value, opens the power valve and applies the step motor when the power valve is open. The second step motor control map has the function of controlling based on the second step motor control map.

[Effect]

In the liquefied petroleum gas supply system for an internal combustion engine configured as described above, when the power valve is switched from closed to open due to an increase in load, the electronic control unit based on the correction value immediately before the power valve opens. The step motor is controlled in a direction in which the opening degree of the variable opening control valve gradually increases.

As a result, the air-fuel ratio of the air-fuel mixture is controlled to gradually become richer, and the power valve is switched to open when the air-fuel ratio reaches a predetermined value. At the same time, the step motor
The opening of the variable opening control valve is controlled in the direction of decreasing the opening of the variable opening control valve based on the step motor control map.

Therefore, the air-fuel ratio changes smoothly until the power valve opens, and as soon as the power valve opens, the amount of fuel supplied from the variable opening control valve decreases, so overall the air-fuel ratio changes smoothly. There is no change in torque, and the shock during acceleration caused by sudden changes in torque is kept to a minimum.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a liquefied petroleum gas supply system for an internal combustion engine according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the invention. In the figure, ■ indicates an internal combustion engine that uses liquefied petroleum gas (hereinafter referred to as rLPGJ) as fuel. In this internal combustion engine 1, a mixture of LP gas and air is supplied from a carburetor 2 and an intake manifold 3 to an intake boat 4.
It is designed to be drawn into the combustion chamber 5 more.

The carburetor 2 includes a venturi portion 7 provided in the middle of the intake passage 6, a main fuel boat 8 and a power fuel boat 9 that are opened toward the intake passage 6 at the hench portion 7, and a main fuel boat 8 and a power fuel boat 9 located downstream from the venturi portion 7. It has a throttle valve 10 provided in the middle of the side intake passage, and an idling operation bypass air passage 11 provided to bypass the throttle valve 10. The main fuel boat 8 is connected to an LPG regulator 15 via a main fuel passage 12 as a first fuel system. LPG regulator 15
is a device that is equipped with a secondary pressure reduction chamber and a secondary pressure reduction chamber, and vaporizes LPG to regulate its pressure. Similarly, the power fuel boat 9 supplies LPG via a power fuel passage 13 as a second fuel system.
It is connected to the regulator 15.

The main fuel passage 12 is provided with a variable opening control valve 16 that adjusts the flow rate of LP gas flowing through the main fuel passage 12. The opening of the variable-degree control well 16 is controlled by a step motor 18 that is controlled based on an electric signal from an electronic control unit (ECU) 17. The step motor 18 operates in steps according to the value of the control n signal outputted from the ECULT, for example, the number of pulses of the pulse signal, and the step value increases as the number of pulses increases, and the valve body 1a opens in the direction of a large opening. It is designed to be moved to

This power fuel passage 1 is located in the middle of the power fuel passage 13.
A power valve 20 that opens and closes 3 is provided. The power valve 2o is opened and closed by an on/off signal from the ECtJ17. power valve 20
is connected to a diaphragm device 23 via a drive lever 22, and the diaphragm device 23 is connected to a negative pressure switching valve (V
SV)26.

In other words, when negative pressure is introduced into the negative pressure chamber 24 of the diaphragm device 23, the power valve 20 is driven to close, whereas when no negative pressure is introduced into the negative pressure chamber 24, the power valve 20 is driven to open. It is designed to be driven. VS
When the V26 is connected to the ECULT and the engine is under high load, the power pulp 20 is opened and the power fuel boat 9 is activated.
A predetermined flow rate of LP gas is ejected from the pump.

An air cleaner 27 is located at the upstream end of the intake passage 6, and an intake temperature sensor 28 is provided between the air cleaner 27 and the bench area 7. Throttle valve 1
A pressure sensor 30 that measures intake pipe negative pressure is provided immediately downstream of the throttle sensor 29 that detects zero opening.

Fuel for the second fuel system is supplied from the primary decompression chamber of the LPG regulator 15. The fuel passage of the second fuel system includes a slow passage 31 on the way, and an auxiliary fuel passage 3 that is provided immediately downstream of the slow valve 10 of the carburetor and supplies fuel to an auxiliary fuel injector 32 that injects auxiliary fuel.
The fuel supply to these passages is controlled by a slow lock valve 34.

The slow lock valve 34 is connected to the intake passage 6 via a check valve 35 to open and close the slow lock valve 34.
This is done by a negative pressure switching valve (VSV) 36 that switches the supply pressure to the intake pipe negative pressure and atmospheric pressure.

VSV36 and auxiliary fuel injector 32 are connected to the ECU
17N is connected. The VSv36 operates based on a signal from the ECULT, and its operation opens and closes the slow lock valve 34 to supply or cut fuel to the slow system passages 31 and 33. Furthermore, the auxiliary fuel injector 32 is configured to be able to change the fuel injection amount upon return from fuel cut based on a signal from the ECULT. The on/off signal of the near conditioner (indicated heat) is input to ECULT, and the EC
The ULT has a built-in circuit that variably controls the signal sent to the auxiliary fuel injector 32 based on this on/off signal. The ECULT also has a distributor 38 connected to the ECULT via an igniter 37.
A reference position signal and a crank angle signal, which are signals for calculating the rotation speed, are input.

Furthermore, a fully closed throttle position signal from a throttle sensor 29 is also input to the ECU 17, so that it can be determined when the engine is decelerating.

Note that 48 is an oxygen concentration sensor attached to the exhaust pipe 39, 40 is an exhaust temperature sensor, and 41 is an engine water temperature sensor, and these signals are also input to the ECU 17. 4
2 is a VSV that controls the operation of the EGR pulp 43, 44 is a VSV that controls the operation of a swirl control valve (SCV) 45 that controls the flow direction of intake air, and the operation of these VSVs is also controlled based on signals from the ECU 17. be done.

The ECU 17 includes a first step motor control map that is applied when the power valve 20 is closed when the opening degree of the throttle valve 10 becomes a predetermined opening degree or more when the power valve 20 is switched from closed to open. (S3MAP) has a function of adding a correction value SVL that increases the step value of the step motor as time passes. Furthermore, the ECU 17 opens the power valve 20 when the correction value SVL reaches a predetermined value KVL, and controls the step motor 18 based on a second step motor control map (SIMAP) that is applied when the power valve 20 is open. It also has a function to control it.

3 and 4 show respective control maps for the step motor. FIG. 3 shows the first step motor control map applied when the power valve 20 is in the closed state, and as shown in the figure, the horizontal axis shows the engine rotation speed N.
The intake pipe negative pressure PM is plotted on the ES vertical axis. therefore,
At low loads, the step motor 18
is controlled, and the opening of the variable opening control valve 16, that is, the position of the valve body 18, is adjusted to one of regions A to D. Fourth
The figure shows a second step motor control map that is applied when the load increases and the power valve 20 is in the open state, and the horizontal axis shows the engine rotation speed NB, as described above.
The vertical axis represents the intake pipe negative pressure PM.

That is, at the time of high load such as during acceleration, the step motor 18 is controlled based on the relationship between the two, and the position of the valve body 18 of the variable opening control valve 16 is adjusted to one of the ranges E-1.

Next, the operation of the liquefied petroleum gas supply system for the internal combustion engine described above will be explained.

First, the control of the variable opening control valve 16 and the power valve 20 will be explained based on the flow diagram of FIG. 2. As shown in FIG. In step 101, it is determined whether the power valve 20 is open or closed. As a result, if the power valve 20 is closed, the process proceeds to step 102, and the opening degree VL of the throttle valve 10 reaches the predetermined opening degree Tθ.
It is determined whether or not the value is greater than or equal to the value. If the opening degree VL of the throttle valve 10 is larger than the predetermined opening degree Tθ, the process proceeds to step 103, where a flag FSVL indicating whether correction control of the step motor is being performed is determined. At the beginning of the routine, FSVL-0, that is, correction control of the step motor is not being performed, so the process proceeds to step 104, where the mo flag FSVL is set. Next, the process proceeds to step 105, where the step motor correction amount is initialized to zero, and then, the process proceeds to step 106, where a timer for counting the step motor correction cycle amount is activated.

Then, in step 107, the correction 1SvL is applied to the first step motor control '1B 77B (33MAP).
The step motor is controlled using the added value as the step position, and the routine proceeds to step 116, where the routine ends.

Returning to the previous step, if the power valve 20 is open in step 101, that is, if the load is high, the process immediately proceeds to step 114, and the step motor 18 is switched to the second step motor 18.
The step position is calculated based on the engine speed NE and intake pipe negative pressure PM of the step motor control map (SIMAP), and the opening degree of the variable opening control valve 16 is adjusted. Thereafter, the routine proceeds to step 116 and ends. Further, in step 102, if the opening degree VL of the throttle valve 10 is less than the predetermined opening degree Tθ, that is, if the load is low, the process proceeds to step 115, and the step motor 1 is switched to the first step motor. Control statement/knob (S3MAP) engine speed NE, intake pipe negative pressure PM
The step position is calculated by
The opening degree is adjusted. Thereafter, the process advances to step 116 and the routine ends.

Next, in step 103, the flag will be set to FSVL-1 at the next time interrupt, so in this case, the process proceeds to step 108, where it is determined whether the timer has elapsed for a predetermined period of time.

Here, if the elapsed time has not reached the predetermined cycle itJ]T o , the process immediately proceeds to step 107 and the step motor 18 is controlled. When the predetermined time has elapsed, step 109
The correction value SVL is incremented in step 110, and it is determined in step 110 whether this correction value SVL has reached a predetermined value KVL.As a result, the correction value SVL is incremented.
If L has not reached the predetermined value KVL, step 1
Proceed to step 06 to restart the timer and end this routine. In step 110, if the correction value SVL has reached the predetermined value KVL, the process proceeds to step 111, where the power valve 20 is opened, and in step 112, the flag FSVL indicating that correction control is in progress is cleared, and this correction control is terminated. do. Then, the process immediately proceeds to step 113, where the step motor 18 is controlled based on the second step motor control (SIMAP) applied when the power valve is open, and the routine ends.

In this way, immediately before the power valve 20 changes from closed to open, as shown in FIG. 5, the opening of the variable opening control valve 16 changes over time to a certain step value on the first step motor control map. Since the correction value SVL is added to the predetermined value KVL so that the opening degree gradually increases, the amount of LP gas supplied from the variable opening control valve 16 to the venturi section 7 is gradually increased, and the air-fuel ratio is It is changed little by little until point P where it becomes open. Then, the opening degree of the variable opening control valve 16 is returned to an appropriate opening degree as shown by arrow Q at the same time as the power valve 20 is opened. therefore,
Changes in the air-fuel ratio are significantly smoother than with conventional equipment,
Engine torque fluctuations associated with air-fuel ratio control are suppressed to a small level, and shocks during acceleration are suppressed to a virtually negligible level.

〔Effect of the invention〕

As explained above, when using the liquefied petroleum gas supply system for an internal combustion engine of the present invention, the electronic control unit adds a correction value to the first step motor control map when the power pulp is switched from closed to open. control the step motor,
When the correction value reaches a predetermined value, the power valve is opened and the step motor is controlled based on the second step motor control map, so the air-fuel ratio changes when the power valve is switched from closed to open. can be smoothed. As a result, engine torque fluctuations are suppressed to a small level, and it is possible to prevent shock from occurring during acceleration due to air-fuel ratio control.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a liquefied petroleum gas supply device for an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a flow diagram of control in the device of FIG. 1, and FIG. 3 is a first step motor control Fig. 4 shows the second step motor control map, and Fig. 5 shows the elapsed time and the opening of the variable opening control valve when the correction value is added to the step value of the first step motor control map. FIG. 10... Throttle valve 12... First fuel system (main fuel passage) 13
...Second fuel system (power fuel passage) 16...
...Variable opening control valve 17...Electronic ML unit (ECU) 18.
...Step motor 20...Power valve ss MAP...First step motor control map SI MAP...Second step motor control map SVL... ···Correction value

Claims (1)

[Claims] (1) A first fuel system in which a variable opening control valve whose opening degree is continuously varied by a step motor controlled based on an electric signal from an electronic control device; a second fuel system in which a power valve that is opened and closed by an on/off signal is disposed, and when the load is low, the power valve is closed and the air-fuel ratio is controlled by fuel supply from the variable opening control valve; In an internal combustion engine that uses liquefied petroleum gas as fuel, in which the air-fuel ratio is controlled by fuel supply from both a variable opening control valve and a power valve during high loads, the electronic control device is configured to control the air-fuel ratio by supplying fuel from both a variable opening control valve and a power valve. In the case where the throttle valve is switched and the opening degree of the throttle valve becomes more than a predetermined opening degree, the step value of the step motor is increased as time passes in the first step motor control map that is applied when the power valve is closed. A function of adding a correction value, and a function of opening a power valve when the correction value reaches a predetermined value and controlling the step motor based on a second step motor control map that is used when the power valve is open. A liquefied petroleum gas supply device for an internal combustion engine, characterized by having the following features.