JPH0726596B2 - LPG fuel supply control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an LPG for supplying fuel to an internal combustion engine using LPG fuel.
The present invention relates to a fuel supply control device.

[Prior Art] Conventionally, in an internal combustion engine using an LPG fuel, the LPG fuel is used as a vapor phase fuel, and this vapor phase fuel is blown into a carburetor which is an air mixing device to be used as a driving fuel for the internal combustion engine.
This state is shown in the fuel system diagram of FIG. 7th
As shown in the figure, the LPG fuel stored in the liquid state in the fuel tank FT is supplied to the regulator RE via the filter FI.
Flowing into the LPG in the gas phase state at the specified pressure with the regulator RE.
After being used as fuel, it flows into the carburetor CB and is used as driving fuel for the internal combustion engine EG.

On the other hand, in addition to the internal combustion engine using the LPG fuel shown in FIG. 7, when the internal combustion engine is operated at a low load as shown in the invention and proposal of “LPG fuel switching device” and the like in Japanese Utility Model Laid-Open No. 55-60437.
Proposals have also been made to use gas phase fuel as LPG fuel and liquid phase fuel during high load operation.

[Problems to be Solved by the Invention] However, an internal combustion engine using LPG fuel causes a reduction in output during high-load operation or the like as compared with an internal combustion engine using gasoline fuel. This is the LP that is increased during high load operation.
This is because the amount of intake air decreases due to G fuel. The proposals such as the above "LPG fuel switching device" were made for the purpose of preventing the reduction of the output during the high load operation. Although the use of liquid phase fuel is switched, even if the liquid phase fuel is used during high load operation, the liquid phase LPG fuel atomized by the carburetor vaporizes to the combustion chamber, reducing the intake air amount. Therefore, it was considered that the output would decrease, so that the problem of the output reduction during high load operation of the internal combustion engine using LPG fuel was still an unsolved problem.

Structure of the Invention [Means for Solving Problems] The structure of the LPG fuel supply control device of the present invention for solving the above problems is as follows. That is, the LPG of the present invention
As shown in the basic configuration of FIG. 1, the fuel supply control device uses LPG fuel stored in a liquid phase state in an internal combustion engine (M
1) Gas-phase fuel supply means (M2), operating state detection means (M3) for detecting the operating state of the internal combustion engine (M1) including at least the load, and detection by the operating state detection means (M3) The internal combustion engine fuel control means (M4) for controlling the vapor phase fuel supply means (M2) based on the operating state of the internal combustion engine (M1), and the LPG fuel supply control device comprising: A liquid phase fuel supply means (M6) for directly supplying to the combustion chamber (M5) of the internal combustion engine (M1) in a liquid phase state is provided, and the internal combustion engine fuel control means (M4) includes the operating state detection means ( A liquid phase fuel control means (M7) for controlling the liquid phase fuel supply means (M6) based on the operating state of the internal combustion engine (M1) detected by M3) is provided.

Here, the gas-phase fuel supply means (M2) is a means for supplying the LPG fuel stored in the liquid phase state to the internal combustion engine (M1) in the gas phase state, for example, in a fuel tank or the like in the liquid phase state. After making the stored LPG fuel into a vapor phase state of a predetermined pressure using a regulator, etc., using a carburetor and a throttle valve,
The LPG fuel in the gas phase state is configured to be supplied to the internal combustion engine (M1), or the LPG fuel in the fuel tank that has changed from the liquid phase state to the gas phase state is directly supplied to the internal combustion engine (M1) using an injector or the like. Various configurations can be considered, such as a configuration in which the fuel is injected into the combustion chamber (M5).

The operating state detecting means (M3) is a means for detecting an operating state of the internal combustion engine (M1) including at least a load, and a pressure sensor for detecting a negative pressure in the intake pipe that reflects the load of the internal combustion engine (M1). It can be configured using various sensors such as a rotation speed sensor that detects the rotation speed of the internal combustion engine (M1) or an O ² sensor used for detecting the air-fuel ratio of the internal combustion engine (M1). The operating state of the internal combustion engine (M1) includes those indirectly related to the operating state of the internal combustion engine (M1), such as the pressure and temperature of the LPG fuel in the fuel tank.

The internal combustion engine fuel control means (M4) is a means for controlling the gas phase fuel supply means (M2) based on the operating state of the internal combustion engine (M1) detected by the operating state detecting means (M3). It is conceivable to use a lean circuit or a logical operation circuit to control the opening degree of a throttle valve or the like and the valve opening time of an injector or the like.

The liquid-phase fuel supply means (M6) is a means for directly supplying the LPG fuel in a liquid phase state to the combustion chamber (M5) of the internal combustion engine (M1), and is stored in a fuel tank or the like in a liquid phase state, for example. It can be considered that the LPG fuel is directly supplied to the combustion chamber (M5) of the internal combustion engine (M1) by using an injector or the like.

Liquid phase fuel control means (M7) means operating state detection means (M3)
Means for controlling the liquid-phase fuel supply means (M6) based on the operating state of the internal combustion engine (M1) detected by the microcomputer, which uses a microcomputer or the like together with the internal combustion engine fuel control means (M4). It can be considered to configure it as a logical operation circuit.

The liquid-phase fuel supply means (M6) controlled by the liquid-phase fuel control means (M7) is controlled together with the gas-phase fuel supply means (M2) controlled by the internal-combustion engine fuel control means (M4). The liquid phase LPG fuel and the gas phase LPG fuel may be simultaneously supplied to (M1), or the internal combustion engine (M1) detected by the operating state detection means (M3)
When the load and / or the number of revolutions of each of them have become larger than a predetermined value, the gas phase LPG fuel supplied from the gas phase fuel supply means (M2) is gradually reduced and supplied by the liquid phase fuel supply means (M6). It does not matter if the LPG fuel in the liquid phase is gradually increased.

[Operation] The LPG fuel supply control device of the present invention operates as follows.

The LPG fuel supply control device of the present invention comprises an operating state detecting means (M
3) Based on the operating state of the internal combustion engine (M1) detected by the internal combustion engine fuel control means (M4), the vapor phase fuel supply means (M2) is controlled to supply the LPG fuel in the vapor phase state to the internal combustion engine (M
1) supplied to the internal combustion engine (M1) detected above
The liquid-phase fuel control means (M7) controls the liquid-phase fuel supply means (M6) based on the operating state of so that the LPG fuel in the liquid-phase state is directly supplied to the combustion chamber (M5) of the internal combustion engine (M1). work.

[Embodiment] Next, a preferred embodiment will be described with reference to the drawings in order to further clarify the configuration of the LPG fuel supply control of the present invention.

FIG. 2 is a schematic configuration diagram showing an LPG fuel supply control device of one embodiment of the present invention.

As shown in the figure, the LPG fuel supply control device of the present embodiment is
The LPG fuel FL stored in the fuel tank 1 in the liquid phase is supplied to the inside of the cylinder 5 of the engine 3 mounted on the vehicle from the gas phase injector 7 or the liquid phase injector 9 attached to the cylinder head 6 or It is configured to be injected and supplied as liquid phase fuel. Fuel tank 1
The LPG fuel FL in the inside is injected from the gas-phase injector 7 or the liquid-phase injector 9 after being made into the gas-phase fuel of a predetermined pressure by the regulator 11 or after being made into the liquid-phase fuel of the predetermined pressure by the pressurizing pump 13. To be done. The injection timing and injection amount of the gas-phase injector 7 and the liquid-phase injector 9 are controlled by an electronic control unit (hereinafter simply referred to as ECU) mounted on the vehicle.
Determined by It should be noted that the cylinder head 6 has a third portion showing a state in which the cylinder 5 of the engine 3 is viewed from above.
As shown in the figure, in addition to the vapor-phase injector 7 and the liquid-phase injector 9, a known ignition plaque 17, an intake pipe 18, an exhaust pipe 19 and the like are also provided.

As shown in FIG. 2, the ECU 15 is a well-known CPU 20, ROM 21, RAM
It is configured as a logical operation circuit in which an input circuit 23, an output circuit 24 and the like centering on 22 and the like are connected to each other by a bus 25.

The input circuit 23 of the ECU 15 includes a negative pressure sensor 31 for detecting a negative pressure Pa in the intake pipe 18 of the engine 3 and a rotation speed N of the engine 3.
The rotation speed sensor 32 for detecting the temperature is connected, the pressure sensor 35 for detecting the pressure in the fuel tank 1 and the temperature sensor 36 for detecting the temperature of the LPG fuel are connected, and the liquid after passing through the pressurizing pump 13 is connected. Pressure sensor for detecting the pressure of two-phase fuel
37 mag is also connected.

On the other hand, the output circuit 24 includes a gas phase injector 7 and a liquid phase injector 9 attached to the cylinder head 6 of the engine 3.
And the spark plug 17 and the like. This allows
ECU15, the operating state of the vehicle input from the input circuit 23,
For example, the negative pressure in the intake pipe 18 that reflects the load of the engine 3
Based on Pa and the like, processing such as determining the injection timing and injection amount of the gas phase injector 7 and the liquid phase injector 9 is performed.

Next, the process of supplying the LPG fuel FL to the engine 3 by the ECU 15 will be described using the "fuel control routine" shown in FIG.

The "fuel control routine" shown in FIG. 4 represents the operation relating to the processing of injecting the LPG fuel FL into the cylinder 5 from the gas phase injector 7 or the liquid phase injector 9 among the various processing executed by the ECU 15. That is, as shown in FIG. 5, it is executed at a predetermined timing in the intake process T.

First, in step 100, the operating state of the engine 3 is input. In this embodiment, in this process, the negative pressure sensor 31, the rotation speed sensor 32, the pressure sensor 35, the temperature sensor 36,
The negative pressure Pa in the intake pipe 18, the rotational speed N of the engine 3, the pressure Pb in the fuel tank 1, the temperature of the LPG fuel FL by the pressure sensor 37 and the like.
Tp, liquid fuel pressure Pc, etc. are read.

When the above process is completed, the process proceeds to the following step 110,
Here, the fuel injection condition is determined. That is, when the intake air amount sucked into the intake pipe 18 is equal to or more than a certain intake air amount (15 g / sec in this embodiment), the liquid phase fuel injected from the liquid phase injector 9 is used as the LPG fuel FL. At other times, it is determined to use the liquid phase fuel injected from the gas phase injector 7. Note that this predetermined intake air amount is the sixth
As shown in the figure, the engine speed N and the suction negative pressure Pa are stored in the ROM 21 in advance (in FIG. 6, the shaded area is the gas phase fuel use area).

When it is determined to use the gas-phase fuel, that is, the engine 3
Is low / medium load, low / medium speed, the process is step 12
On the other hand, when it is determined to use the liquid phase fuel, that is, when the engine 3 has a high load and a high rotation speed, the process proceeds to steps 140 to 150.

In step 120, the gas-phase fuel injection amount Qa injected from the gas-phase injector 7 is calculated. This gas-phase fuel injection amount Qa
Is basically determined by the negative pressure Pa in the intake pipe 18 and the engine speed N, and is the pressure Pb of the fuel tank 1 and the temperature Tp of the LPG fuel FL.
Etc. will be corrected. The following formula (1) shows a formula for calculating the gas-phase fuel injection amount Qa.

Qa = QBSE × K1 (1) Here, QBSE is a basic injection amount basically determined by the negative pressure Pa and the engine speed N, and K1 is a correction coefficient based on the pressure Pb and the temperature Tp.

Then, the gas-phase injector 7 is opened for a period of time corresponding to the calculated gas-phase fuel injection amount Qa, and the LP
The vapor fuel of G fuel FL is injected (step 130).

On the other hand, in steps 140 to 150,
The liquid-phase fuel injection amount Qb is calculated in the same manner as 120 to 130 (step 140), the time liquid-phase injector 9 is opened according to the calculated liquid-phase fuel injection amount Qb, and the LP is fed into the cylinder 5.
Liquid fuel of G fuel FL is injected (step 150). still,
The following formula (2) is a formula for calculating the liquid-phase fuel injection amount Qb. Here, the pressure Pc of the liquid-phase fuel by the pressure sensor 37 is used for correcting the injection amount of the liquid-phase fuel injection amount Qb.

Qb = QBSE × K2 (2) Here, QBSE is the basic injection amount, and K2 is a correction coefficient based on the pressure Pc and the temperature Tp.

According to the LPG fuel supply control apparatus of the present embodiment described in detail above, the LPG in the gas phase state when the operating state of the engine 3 is low / medium load or the engine speed N is low / medium speed.
The fuel FL is directly injected into the cylinder 5, and when the load is high and the rotation speed is high, the LPG fuel FL in the liquid phase state is directly injected into the cylinder 5. As a result, the LPG fuel supply control device of the present embodiment can obtain a lean air-fuel ratio by the LPG fuel FL in the gas phase when the engine 3 is operating at low / medium load or low / medium / high revolutions. At the same time, when the operating condition is high load and the rotational speed is high, the inflow of the intake air amount from the intake pipe 18 is not controlled, and as a result, high output can be obtained even when the operating condition is high load. It has an excellent effect that In addition, the liquid phase injector 9
The liquid phase LPG fuel FL atomized and injected by
By being injected into the low-pressure cylinder 5 after being pressurized to a predetermined high pressure by the pressurizing pump 13, it has the effect of being further vaporized by the low-pressure boiling action and so on. As a result, the air in the cylinder 5 is cooled, the air density is increased, and the intake air amount can be further increased and a high output can be obtained.

In the present embodiment, the LPG fuel FL in the gas phase state is converted into the gas phase fuel of a predetermined pressure by using the regulator 11, and the LPG fuel FL in the liquid phase state is used.
Although the LPG fuel FL is configured to be pressurized to a predetermined pressure using the pressurizing pump 13, it is also possible to directly inject the LPG fuel FL from the gas-phase injector 7 and the liquid-phase injector 9, respectively. Further, when using the liquid-phase fuel, a heater or the like is provided on the surface of the fuel tank 1 or the gas phase portion so that the temperature in the fuel tank 1 does not drop sharply due to latent heat of vaporization and the gas capacity of the LPG does not become insufficient. Then, the LPG gas shortage may be detected and heated by the temperature / pressure change detected by the pressure sensor 35, the regulator 11 and the like.

Effects of the Invention According to the LPG fuel supply control device of the present invention described in detail above, it has an excellent effect that a high pressure can be extracted from an internal combustion engine using LPG fuel with a simple configuration.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram illustrating an LPG fuel supply control device according to the present invention, FIG. 2 is a schematic configuration diagram showing a configuration of an LPG fuel supply control device according to an embodiment of the present invention, and FIG. 3 is an upper surface of a cylinder thereof. FIG. 4 is a flowchart showing a “fuel control routine” executed by the ECU 15, and FIG. 5 is a diagram showing an intake process T at the timing when the “fuel control routine” is executed.
FIG. 6 is an operation diagram showing a region where the liquid-phase injector 9 is used and operates, and FIG. 7 is a fuel system diagram showing a fuel system in a conventional internal combustion engine using LPG fuel. 1 …… Fuel tank 3 …… Engine 5 …… Cylinder 6 …… Cylinder head 7 …… Gas phase injector 9 …… Liquid phase injector 15 …… Electronic control unit (ECU) 17 …… Ignition plug 18 …… Intake pipe 19 ...... Exhaust pipe 35 …… Pressure sensor 36 …… Temperature sensor 37 …… Pressure sensor CB …… Carburettor EG …… Internal combustion engine FI …… Filter FT …… Fuel tank RE …… Reducer FL …… LPG fuel

Claims (2)

[Claims] 1. A gas phase fuel supply means for supplying LPG fuel stored in a liquid phase state to an internal combustion engine in a gas phase state, and an operating state detection means for detecting an operating state of the internal combustion engine including at least a load, An LPG fuel supply control device comprising: an internal combustion engine fuel control means for controlling the vapor phase fuel supply means based on the operating state of the internal combustion engine detected by the operating state detection means; In the state, liquid phase fuel supply means for directly supplying to the combustion chamber of the internal combustion engine is provided, and the internal combustion engine fuel control means includes the liquid based on the operating state of the internal combustion engine detected by the operating state detecting means. An LPG fuel supply control device, comprising: a liquid phase fuel control means for controlling the phase fuel supply means. 2. The liquid-phase fuel control means controls the liquid-phase fuel supply means to control the liquid-phase fuel supply means when the load and / or the rotational speed of the internal combustion engine detected by the operating state detection means are larger than respective predetermined values. The above supplied to the internal combustion engine
From LPG fuel in the gas phase to LPG in the liquid phase
The LPG fuel supply control device according to claim 1, which switches to G fuel.