KR101786110B1 - Bi-Fuel Exchange System for Bi-Fuel Vehicle and Bi-Fuel Exchanging Control Method thereof - Google Patents

Abstract

Fuel conversion apparatus of the present invention further includes fuel switching-fuel compensation logic for calculating the fuel compensation value in consideration of the physical characteristics of the two fuels when switching between gasoline and LPG, Fuel conversion at the time of interchange of LPG - fuel conversion compensation logic to prevent the wall film effect obtained by the correction of the fuel film effect (Wall Film Effect) to prevent the performance of the engine running without any difference, gasoline-LPG vehicles, And can satisfactorily cope with exhaust gas regulations reinforced by improvement of exhaust gas.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bi-fuel vehicle,

The present invention relates to a dual fuel vehicle, and more particularly, to a fuel switching device for a dual fuel vehicle and a fuel control method using the fuel switching device, in which a difference in air fuel ratio due to fuel conversion is not generated by compensating a fuel amount during fuel switching.

Generally, dual fuel vehicles refer to the case where power is generated by using different kinds of fuel such as gasoline / diesel-liquefied petroleum gas (LPG) / liquefied natural gas (CNG).

This dual fuel vehicle requires a system that can use all kinds of fuels. For example, in the case of a gasoline-LPG combined vehicle, there is a gasoline fuel system for supplying ordinary gasoline fuel to the engine. In addition, They will be equipped with the necessary LPG fuel system, such as Vaporizer, Mixer and Elpie Fuel Tank (Bombe).

Typically, fuel conversion from gasoline to LPG or from LPG to gasoline is implemented by analyzing the signal of the injector.

Korean Patent Publication No. 10-2010-0059497 (June 4, 2010).

The patent document discloses a method of controlling a fuel injector in a Liquid Phase LPG (LPLI) method or a GDI (Gasoline Direct Injection) method using a peak-and-hold current control method, ), And the LPG (or CNG) fuel control ECU receives the signal from the liquid fuel control ECU which analyzes the injector control signal input to the injector signal analyzing unit, thereby switching the fuel to LPG (or CNG) It is possible to do it.

3 shows a diagram for performing fuel switching using an injector signal, from which a liquid fuel control ECU controls an LPG (or CNG) fuel control ECU based on an injector analysis signal, It can be seen that the control ECU controls the gas injection injector so that LPG (or CNG) fuel corresponding to the liquid fuel amount is supplied to the engine.

This makes it possible to improve the fuel efficiency and improve the fuel efficiency in the use of LPG (or CNG) fuel, without affecting the vehicle condition by supplying LPG (or CNG) Regulatory satisfaction as well as engine power can be improved.

However, even in the case of the above-mentioned patent documents, most of the dual fuel systems using gasoline and LPG are equivalent to the fuel switching control, so that the fuel amount is not compensated for when the fuel is switched. Thus, when switching from gasoline to LPG or switching from LPG to gasoline, A difference occurs.

This air-fuel ratio difference is due to the inevitable aspect due to the difference in the volumetric difference between the gasoline and the LPG, and the difference in the wall film (wetting effect) of the engine cylinder combustion chamber.

Therefore, if the fuel is converted to gasoline while using LPG as fuel, additional fuel injection increase immediately after the gasoline fuel conversion can compensate for the difference in the barrier effect, thereby reducing the difference in the air fuel ratio.

Therefore, there is a need to add a dual fuel conversion device for increasing the fuel injection amount immediately after the fuel switching and logic for more effective control thereof.

In view of the above, the present invention, which has been made in view of the above, has an object to provide a fuel injection control apparatus and a fuel injection control method of a fuel injection control apparatus, Fuel conversion device of a dual fuel vehicle in which a difference in air-fuel ratio due to fuel conversion does not occur even when a gaseous fuel and a liquid fuel which are fundamentally volatile are used are added by being added to compensate for the wall film effect of the combustion chamber And to provide a fuel control method using the same.

According to an aspect of the present invention, there is provided a fuel switching system for a dual fuel vehicle, comprising: a liquid fuel system for injecting liquid fuel into a combustion chamber of an engine;

A gas fuel system for injecting gaseous fuel into the combustion chamber of the engine;

An ECU (Engine Control Unit) further including an output signal generation logic for controlling the injection timing and the injection amount of the liquid fuel through the liquid fuel system and for controlling the injection timing and the injection amount of the gaseous fuel;

An interface box (IFB) for controlling an injection timing and an injection amount of gaseous fuel through the gas fuel system with an output signal transmitted from the ECU in association with the ECU;

A fuel changeover switch for generating a corresponding signal upon switching from the liquid fuel to the gaseous fuel or vice versa and transmitting the signal to the ECU or the IFB;

And a control unit.

The IFB controls the fuel injection of the gaseous fuel system in accordance with the output signal of the ECU, while the ECU receives an output signal to the IFB through the fuel conversion-fuel compensation logic at the time of fuel switching according to the signal of the fuel change- It provides.

The fuel conversion-fuel compensation logic calculates a fuel amount required according to the fuel determined at the time of fuel switching according to the signal of the fuel change-over switch, calculates a fuel amount correction value according to the fuel determined to prevent the wall film effect of the combustion chamber And the actual fuel injection amount is calculated by associating the fuel amount correction value with the required fuel amount.

The required amount of fuel calculation is calculated in consideration of cooling water temperature, engine speed (RPM) and injection conditions (fuel injection time, number of fuel injections and combustion cylinder quantity) when switching from gas to liquid, While calculating the fuel amount correction value in consideration of the engine rotation speed (RPM) and the injection time when converting from gas to liquid, the calculation of the fuel amount correction value is carried out from the liquid to the gas The engine revolution (RPM) and injection time are calculated by subtracting the value of the gas required fuel amount applied and the reference liquid basic fuel amount corresponding to the intake air amount.

The fuel amount correction value is set to be smaller as the coolant temperature is higher and the engine speed (RPM) is increased.

In order to achieve the above object, the fuel control method using the fuel switching device for a dual fuel vehicle according to the present invention is a method for controlling a fuel using a liquid fuel and a gaseous fuel A fuel conversion recognition step of checking whether a signal to be converted into liquid fuel is generated;

If there is a fuel switching request signal, it is determined whether the switching from the liquid fuel to the gaseous fuel or the switching from the gaseous fuel to the liquid fuel is made, and the fuel injection amount of the switching fuel, Step;

A combustion executing step of calculating a substantial injected fuel amount using the calculated fuel injection amount and a fuel amount correction value applied thereto and injecting the substantially injected fuel amount into a combustion chamber of the engine;

A fuel switching completion step of continuously or intermittently controlling the engine based on the application time and the number of times of cylinder combustion when the engine is controlled by the actual injection fuel amount,

Is executed.

Gasoline or diesel is applied to the liquid fuel, and LPG or CNG is applied to the gaseous fuel.

The calculation of the fuel injection amount of the converted fuel is performed in consideration of the cooling water temperature, the engine speed (RPM) and the injection condition (fuel injection time, number of fuel injections and combustion cylinder quantity) when switching from gas to liquid, The calculation of the fuel amount correction value applied to the fuel injection amount of the converted fuel is performed based on the engine rotation speed (RPM) and the injection time in the conversion from the gas to the liquid While the engine speed (RPM) and injection time are calculated by subtracting the amount of gas required fuel applied and the reference liquid basic fuel amount corresponding to the amount of intake air when switching from liquid to gas.

The fuel amount correction value is set to 0 to 1, or to a physical amount with respect to the liquid injection amount or the gas injection amount, and is set smaller as the coolant temperature increases and as the engine speed (RPM) increases.

The fuel change recognition step is repeatedly executed repeatedly during the engine operation if no signal is generated from the liquid fuel to the gaseous fuel or from the gaseous fuel to the liquid fuel.

The present invention compensates the volatile difference between the two fuels with the compensation logic by hardware while using the gas fuel (LPG or CNG) and the liquid fuel (gasoline or diesel) in duplicate, Wall Film Effect) compensation, it is effective not to generate the performance difference.

In addition, the present invention can improve the operability and the emission gas because there is no occurrence of the performance difference due to the fuel conversion while using the gas fuel (LPG or CNG) and the liquid fuel (gasoline or diesel) There is an effect that it is possible to respond satisfactorily to emission gas regulations while enhancing the merchantability of the vehicle.

2 is a fuel conversion-fuel compensation logic for fuel compensation in the fuel switching according to the present invention, and Fig. 3 is a graph showing the fuel conversion- Signal to perform fuel conversion.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which illustrate exemplary embodiments of the present invention. The present invention is not limited to these embodiments.

1 shows a configuration of a dual fuel vehicle for performing fuel compensation in fuel switching according to the present embodiment.

As shown in the figure, the dual fuel vehicle includes an engine 1 that generates power, a liquid fuel system 2 that injects the liquid fuel into the combustion chamber of the engine 1, and a fuel injection system that injects the gaseous fuel into the combustion chamber of the engine 1 And an ECU (5) for controlling the injection timing and the injection amount of the liquid fuel through the liquid fuel system (2) and further including signal generation logic for controlling the injection timing and the injection amount of the gaseous fuel, An interface box (IFB) 7 (Interface Box) which is linked to the ECU 5 and controls the injection timing and injection amount of the gaseous fuel through the gaseous fuel system 3, And a fuel changeover switch 10 for generating an electric signal corresponding to the detected electric signal.

The engine 1 is configured with all the devices related to intake and exhaust, which is the same as a conventional engine system.

The liquid fuel system 2 includes a gasoline fuel tank, a fuel line for supplying gasoline and a fuel injection nozzle, and the like, and the fuel injection control The ECU 5 and the control circuit.

In addition, the liquid fuel system 2 includes all the equipment normally required for the supply and control of gasoline, which is a conventional configuration.

In this case, however, the liquid fuel system 2 includes a fuel tank for injecting diesel fuel into the combustion chamber, a common rail for transferring the fuel, a high-pressure injection device, a fuel injection injector, and the like And constitutes the ECU 5 and the control circuit for fuel injection control.

In addition, the gas fuel system 3 is applied with LPG as gaseous fuel. To this end, the gas fuel system 3 includes an LPG fuel tank (Bombe) necessary for LPG fuel use, a fuel line for supplying LPG, A mixer for mixing and an LPG supply controller and the like constitute a control circuit and an IFB 7 linked to the ECU 5 for fuel injection control.

In addition, the gas fuel system 3 includes all the equipment normally required for LPG supply and control, which is in accordance with the usual configuration.

In this case, the gas-fuel system 3 is provided with a configuration for using the CNG fuel, and the IFB 7 associated with the ECU 5 for fuel injection control and the control Circuit.

On the other hand, the ECU 5 takes charge of the control of the gasoline fuel and also generates an output signal to be transmitted to the IFB 7 when sensing the signal of the fuel conversion switch 10, (5) further includes fuel conversion-fuel compensation logic.

The fuel conversion-fuel compensation logic calculates a required fuel amount in consideration of various conditions when inputting a fuel conversion signal, calculates a fuel amount correction value according to the fuel conversion type by reflecting the state value of various conditions considered, The performance difference due to the wall film effect of the combustion chamber is not generated.

In this embodiment, the fuel amount calculation is set differently depending on the case of switching from gas to liquid. For example, the gas-to-liquid conversion conditions include the cooling water temperature, the engine speed (RPM) And the condition for liquid -> gas conversion is the gas fuel amount calculation value according to the cooling water temperature and the fuel composition ratio between different kinds of fuel.

Here, the injection condition is defined by the fuel injection time, the number of fuel injections, and the number of combustion cylinders.

Further, the fuel amount correction values are distinguished according to the calculation of the fuel amount.

For example, the liquid compensation value for the liquid fuel amount calculated value in the fuel amount correction value is calculated by applying the engine speed (RPM) and the injection time, and the higher the coolant temperature is, the more the engine speed (RPM) The smaller the value is set.

Here, the liquid compensation value is set to a value between 0 and 1 on the basis of characteristics to be treated as a factor, but it may be set to a physical quantity like a fuel injection quantity depending on the case.

As a result, the substantial liquid fuel injection amount = liquid fuel amount calculation value x liquid compensation value is determined.

The gas compensation value for the gas fuel amount calculation value in the fuel amount correction value is calculated by subtracting the gas required fuel amount value to which the engine speed (RPM) and the injection time are applied and the reference liquid basic fuel amount value corresponding to the intake air amount In this case as well, the liquid compensation value is set to be smaller as the coolant temperature increases and as the engine speed RPM increases. Here, the calculated value of the gaseous fuel amount is a value corresponding to the cooling water temperature and the fuel composition ratio between different kinds of fuel, and the value of the gas required fuel amount is a value indicating the generation of a performance difference (that is, And the injection time is applied as the gas fuel amount calculation value to be used for calculating the fuel amount correction value for not generating the fuel injection amount And the engine speed (RPM) and the liquid fuel amount calculation value calculated based on the injection condition. Therefore, the gas fuel amount calculation value is calculated by subtracting the gas fuel amount value and the reference liquid fuel amount value matching the intake air amount value, which means a difference between the gas fuel amount value and the reference liquid fuel amount value that is adjusted to the intake air amount.

This is because the value of the basic fuel amount based on the intake air amount at the time of calculating the gas compensation value is based on the physical characteristics of the gas, which is caused by the fact that the wall film effect of the combustion chamber is not generated in the case of the liquid- .

Here, the gas compensation value is set to a value between 0 and 1 on the basis of characteristics to be treated as a factor, but it may be set to a physical quantity like a fuel injection quantity depending on the case.

As a result, the actual gas fuel injection quantity = gas fuel quantity calculation value x gas compensation value [gas required fuel quantity value - reference liquid fuel quantity value adjusted to the intake air quantity] is determined.

The IFB 7 controls the fuel injection of the gas fuel system 3 in response to the output signal of the ECU 5 and the IFB 7 constitutes a control circuit associated with the ECU 5 Thereby constituting a control circuit associated with the fuel control device of the gas fuel system 3.

In the present embodiment, the IFB 7 is not limited to an interface function for transferring only a control signal without having logic for controlling the fuel control device of the gas fuel system 3, And may have a role sharing with the ECU 5 by having some of the control logic.

Then, the fuel changeover switch 10 generates an electric signal corresponding to the switching from the liquid fuel to the gaseous fuel or vice versa, and the signals generated therefrom are transmitted to the ECU 5 and the IFB 7, respectively Configure the circuit.

Thereby, the ECU 5 judges the fuel switching timing and executes the control logic accordingly, and the IFB 7 can control the gas fuel system 3 so as to be ready in a ready state that can be matched to the fuel switching timing do.

2 shows fuel conversion-fuel compensation logic according to this embodiment.

When the engine is operated as in step S10, it immediately detects whether or not a signal is being transmitted from the fuel changeover switch 10 through step S20.

The signal of the fuel changeover switch 10 is transmitted to both the ECU 5 and the IFB 7 but the detection of the signal of the fuel changeover switch 10 is performed through the ECU 5. [

If it is determined in step S30 that the fuel switching is requested by the fuel switch 10, if the fuel switching request is not received, the process returns to step S20 and a signal is transmitted from the fuel switching switch 10 And continues to detect whether or not it is becoming.

On the other hand, if it is determined in step S30 that there is a fuel change request, the process goes to step S40 to determine the fuel type according to the fuel change request.

The fuel type determined in step S40 is gas -> liquid or liquid -> gas, and in this embodiment, the liquid is gasoline and the gas is LPG.

Then, when the fuel type according to the fuel switching demand is determined through determination in step S40, the fuel injection amount of the switching fuel and the compensation value applied thereto are calculated according to the fuel type determined as in step S50.

In the case of gas-to-liquid conversion in the process executed in step S50, the cooling water temperature, the engine speed (RPM), the injection condition (fuel injection time, number of fuel injections and combustion cylinder quantity) To determine the required gasoline amount calculation value.

Next, the actual injected gasoline amount at which the wall film effect of the combustion chamber may not be generated with respect to the calculated gasoline amount calculation value is determined. To this end, the engine speed (RPM) and injection time are applied, (Gasoline Compensation Factor).

At this time, the gasoline compensation value is set to a physical quantity such as a gasoline injection amount or 0 to 1 yarn due to the characteristics of being treated as a factor, and is set smaller as the coolant temperature increases and as the engine speed (RPM) increases.

When the gasoline compensation value is calculated together with the gasoline amount calculation value as described above, the gasoline compensation value is multiplied to calculate the actual injection gasoline amount value.

As a result, the actual gasoline fuel injection amount = gasoline fuel amount calculation value x gasoline compensation value is determined.

On the other hand, in the case of liquid-to-gas conversion during the process executed in step S50, the LPG amount calculation value is determined by considering the cooling water temperature and the fuel composition ratio between the different types of fuel for calculating the LPG amount.

The LPG Compensation Factor is calculated by subtracting the LPG Compensation Factor from the LPG required fuel amount to which the engine speed (RPM) and injection time are applied and the reference gasoline basic fuel amount to the intake air amount. That is, the LPG compensation value is calculated as the difference between the LPG required fuel amount and the reference gasoline basic fuel amount corresponding to the intake air amount.

At this time, the LPG compensation value is set to a physical quantity such as 0 to 1 or LPG injection quantity due to characteristics of being treated as a factor, and is set smaller as the coolant temperature increases and as the engine speed (RPM) increases.

When the LPG compensation value is calculated together with the LPG amount calculation value as described above, the LPG compensation value is multiplied to calculate the actual injection LPG amount value.

As a result, the actual LPG fuel injection amount = the LPG fuel amount calculation value x LPG compensation value is determined.

After the actual gasoline fuel injection amount or the actual LPG fuel injection amount is calculated through the step S50, the actual gasoline fuel injection amount or the substantial LPG fuel injection amount is injected into the combustion chamber at step S60, and the injection amount application time and the cylinder burning number To determine the fuel conversion cycle.

The fuel switching application period is a combustion cylinder (TI_CYL) > count (COUNT), which means that the actual gasoline fuel injection amount or the actual LPG fuel injection amount after the fuel switching is performed is determined to be applied to the combustion cylinder several times.

Next, in the step S70, as a result of performing the step S60, the gasoline (TI_MES_GSL) = gasoline (TI_BAS_GSL) has no air fuel ratio difference due to the compensation of the wall film effect of the combustion chamber during LPG-> gasoline conversion due to the substantial gasoline fuel injection amount (TI_MAS_GAS) = LPG (TI_BAS_GAS) means that there is no difference in air fuel ratio due to the compensation of the wall film effect of the combustion chamber during the conversion of gasoline to LPG due to the actual LPG fuel injection amount.

As described above, in the fuel switching system for a dual fuel vehicle according to the present embodiment, the fuel switching-fuel compensation logic for calculating the fuel compensation value in consideration of the physical characteristics of two fuels at the time of switching between gasoline and LPG, Fuel conversion in the conversion of gasoline to LPG - Improvement of driving performance even though it is a gasoline-LPG vehicle because the engine is operated with no performance difference due to the prevention of the wall film effect obtained by correcting the amount of fuel injected through the fuel compensation logic It is possible to satisfactorily cope with the exhaust gas regulations reinforced by the improvement of the exhaust gas, while enhancing the merchantability.

1: Engine 2: Liquid Fuel System
3: Gas fuel system 5: ECU (Engine Control Unit)
7: IFB (Interface Box)
10: fuel switch

Claims (11)

A liquid fuel system for injecting liquid fuel into a combustion chamber of an engine;
A gas fuel system for injecting gaseous fuel into the combustion chamber of the engine;
An engine control unit (ECU) further including fuel switching-fuel compensation logic for controlling an injection timing and an injection amount of the liquid fuel through the liquid fuel system, and generating an output signal for controlling the injection timing and the injection amount of the gaseous fuel;
An interface box (IFB) for controlling an injection timing and an injection amount of gaseous fuel through the gas fuel system with an output signal transmitted from the ECU in association with the ECU;
And a fuel changeover switch for generating a signal corresponding to the switching from the liquid fuel to the gaseous fuel or vice versa and transmitting the signal to the ECU or the IFB,
The fuel conversion-fuel compensation logic is calculated in consideration of the injection condition of the coolant temperature, the engine speed (RPM), the fuel injection time and the number of times of fuel injection and the combustion cylinder quantity upon switching from the gaseous fuel to the liquid fuel, (RPM) and injection time when switching from the gaseous fuel to the liquid fuel is calculated in consideration of the cooling water temperature and the gas fuel amount according to the fuel composition ratio between the liquid and the gaseous fuel at the time of switching from the gaseous fuel to the gaseous fuel (RPM) and injection time of the liquid fuel when switching from the liquid fuel to the gaseous fuel, and calculating a correction value of a fuel amount calculated as a difference between the gas fuel amount value to which the engine speed (RPM) and the injection time are applied and the reference liquid basic fuel amount value adapted to the intake air amount , The fuel amount correction value is calculated as the actual fuel injection amount in association with the required fuel amount
Fuel ratio of the fuel.
The fuel switching device of claim 1, wherein the liquid fuel is gasoline or diesel, and the gaseous fuel is LPG or CNG.
The fuel injection control system according to claim 1, wherein the IFB controls fuel injection of the gas fuel system in accordance with an output signal of the ECU, To provide an output signal to the IFB.
2. The method of claim 1, wherein the required fuel amount calculation is performed to calculate a fuel amount required according to the fuel determined at the time of fuel switching according to the signal of the fuel change-over switch, and the fuel amount correction value calculation is performed for preventing the wall film effect Fuel ratio is calculated according to the determined fuel.
delete The fuel switching system of claim 4, wherein the fuel amount correction value is set to be smaller as the coolant temperature is higher and the engine speed (RPM) is increased.
A fuel conversion recognition step of checking whether a signal is generated from the liquid fuel to the gas fuel or from the gaseous fuel to the liquid fuel when the engine operates to generate power by using the liquid fuel and the gaseous fuel together;
If there is a fuel switching request signal, it is determined whether the switching from the liquid fuel to the gaseous fuel or the switching from the gaseous fuel to the liquid fuel is made, and the fuel injection amount of the switching fuel, Step;
A combustion executing step of calculating a substantial injected fuel amount using the calculated fuel injection amount and a fuel amount correction value applied thereto and injecting the substantially injected fuel amount into a combustion chamber of the engine;
And a fuel switching completion step of continuously or intermittently controlling the engine in accordance with the application time and the number of times of cylinder combustion when the engine is controlled by the actual injection fuel amount, ,
The calculation of the fuel injection amount of the converted fuel is performed in consideration of the cooling water temperature, the engine speed (RPM) and the injection condition (fuel injection time, number of fuel injections and combustion cylinder quantity) when switching from gas to liquid, The calculation of the fuel amount correction value applied to the fuel injection amount of the converted fuel is performed based on the engine rotation speed (RPM) and the injection time in the conversion from the gas to the liquid (RPM) and injection time when switching from liquid to gas, calculated as the difference between the gas required fuel amount applied and the reference liquid basic fuel amount corresponding to the intake air amount
Fuel ratio of the fuel to be supplied to the engine.
The fuel control method according to claim 7, wherein the liquid fuel is gasoline or diesel, and the gaseous fuel is LPG or CNG.
delete The fuel injection control system according to claim 7, wherein the fuel amount correction value is set to 0 to 1 or to a smaller value as the engine rotation speed (RPM) increases as the cooling water temperature is higher and is determined by the physical quantity for the liquid injection amount or the gas injection amount. A fuel control method using a fuel switching device of a vehicle.
The dual fuel vehicle according to claim 7, wherein the fuel conversion recognition step is repeatedly executed repeatedly during the engine operation if no signal is generated from the liquid fuel to the gas fuel or from the gaseous fuel to the liquid fuel. Fuel control method using fuel switching device.

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