KR100748663B1 - A fuel line monitoring method of liquified petroleum gas injection vehicle - Google Patents

Abstract

Elpia determines the air-fuel ratio control value by reading the feedback signal of the oxygen sensor placed in the exhaust system in the vehicle, and makes it possible to detect the failure part when the pressure control valve or the pressure sensor among the components in the vehicle's fuel line occurs. This is to prevent error detection for sensors or valves.

The present invention is a process for determining whether the Elpia satisfies the preconditions for the fuel gauge diagnosis if the engine of the vehicle maintains the start-up, and if the preconditions are satisfied, the coolant temperature and the fuel temperature are higher than the reference value and fuel stabilization is maintained. Pressure difference through the process of checking the temperature standard to determine whether it is in a state, setting the fuel model pressure if the temperature standard is satisfied, and monitoring the measured pressure and the model pressure measured in the fuel line when the fuel model pressure is set. If the pressure difference is greater than the set reference value, the process of determining whether the load condition satisfies the fuel gauge monitoring condition, and if the load condition satisfies the fuel gauge monitoring, and checks the air-fuel ratio control value from the signal detected by the feedback from the oxygen sensor Failure of the pressure regulating valve or fuel pressure sensor depending on the procedure and the result of checking the air-fuel ratio control The process of determining whether or not.

ELPI vehicle, fuel gauge monitoring, fuel pressure sensor, pressure regulating valve

Description

A FUEL LINE MONITORING METHOD OF LIQUIFIED PETROLEUM GAS INJECTION VEHICLE}

1 is a system configuration of a typical Elpia vehicle.

2 is a view showing the configuration of a diaphragm type fuel pressure regulating device is applied to the vehicle Elpia.

3 is a flow diagram of one embodiment for performing fuel gauge monitoring in an Elpia vehicle in accordance with the present invention.

The present invention relates to an Elpiai (Liquefied Petroleum Gas Injection) vehicle, and more particularly, to enable the detection of a failure site in the event of a failure of a pressure regulator or a pressure sensor among the parts provided in the fuel line of the vehicle. The present invention relates to an Elpia vehicle fuel gauge monitoring method that prevents error detection of sensors or valves that operate normally.

For example, an Elpia vehicle refers to a vehicle that employs a fuel system in which a fuel pump is installed in a cylinder of an existing LPG vehicle to pump LPG in a liquid state to be injected from an injector. It is possible to solve the problems with the existing LPG vehicles.

LPG fuel increases its volume by 250 times when liquid fuel phase changes into the gas phase due to temperature rise or pressure drop.

Therefore, if the phase change of the liquid fuel occurs during engine operation, the engine stop occurs because the amount of fuel actually introduced into the combustion chamber is only 1/250. Therefore, the phase change of the LPG fuel due to the radiant heat of the engine while driving (including children) occurs. Pressurized and injected fuel contained in the cylinder so as not to occur.

As shown in FIG. 1, the LPI vehicle includes a fuel supply line 20 and a fuel return line including a cylinder 10 for receiving LPG fuel in a liquid state and an injector 50 mounted in a combustion chamber of the engine 40. Connected to 30.

The fuel supply line 20 is provided with a fuel pump 11 for pressurizing and pumping fuel in the cylinder 10, the multi-valve 12 and the shut-off valve 21 downstream of the fuel pump 11 ) And the fuel temperature sensor 22 are sequentially arranged.

The fuel return line 30 injects a pressure control valve 31 and an injector to adjust the pressure to be applied at a constant pressure ΔP and a pressure of approximately 5 bar or more against the pressure of the cylinder 10 in a liquid state in the injector 50. The fuel pressure sensor 32 which detects the pressure of the fuel applied to the 50 is arrange | positioned.

The injector 50, the fuel pump 11, the multivalve 12, the shutoff valve 21, the fuel temperature sensor 22, and the fuel pressure sensor 32 are connected to the electronic control unit 90 via an interface 80. ) Is electrically connected and controlled.

In addition, the intake cylinder 60 includes an intake air temperature sensor 61 for detecting the temperature of the air flowing into the combustion chamber, a map sensor 62 for detecting the amount of air, an idle speed actuator 63, and a throttle operated in conjunction with the accelerator pedal. The throttle position sensor 64 etc. which detect the opening degree of a valve are provided.

The exhaust system 70 is provided with an oxygen sensor 71, and the engine 40 has a crank position for detecting the angle of the crankshaft while the water temperature sensor 41 for detecting the temperature of the coolant and the engine 40 are operated. The sensor 42 is provided.

Each component mounted in the intake system 60, the exhaust system 70, and the engine 40 supplies information necessary for engine operation to the electronic control unit 90 or according to a control signal of the electronic control unit 90. Controlled operation ensures optimal operation.

The pressure control valve 31 disposed in the fuel return line 30 allows the pressure on the fuel supply line 20 to be maintained about 5 bar higher than the pressure inside the cylinder 10.

2, the fuel outlet pipe 31B is formed at the lower center of the valve housing 31A to maintain airtightness at the fuel outlet end of the regulator housing. A plurality of fuel inlets 31C are formed around the lower fuel outlet pipe 31B of the valve housing 31A and disposed to correspond to the fuel inlet end of the regulator housing.

The diaphragm 31D is installed in the center of the valve housing 31A to divide the inside of the valve housing 31A into a diaphragm chamber C1 and a fuel inlet chamber C2, and the diaphragm 31D A valve 31E is installed at the fuel inlet chamber C2 side.

That is, the fuel outlet pipe 31B has an upper end thereof disposed in the fuel inlet chamber C2, and the valve 31E has the valve seat 31F mounted on its lower surface. 31F), the fuel outlet pipe 31B can be opened and closed.

A spring 31G is installed in the diaphragm seal C1 of the valve housing 31A, and the spring 31G is supported by an upper spring seat 31H whose upper end is installed on the upper inner surface of the valve housing 31A. The lower end is supported by the lower spring seat 31I installed at the upper end of the valve 31E to provide a constant elastic force to the valve 31E.

In addition, a pin groove 31J is formed inward at an upper center of the valve 31E, and a core pin 31K is vertically installed at a center of the upper spring seat 31H to be fitted into the pin groove 31J. It is configured to guide the up and down operation of the valve 31E in the state.

Therefore, the conventional pressure regulator 31 having the above configuration has a constant elastic modulus of the spring 31G, and the pressure of the fuel flowing into the fuel inlet 31C returned from the injector 50 is increased. When the elastic force of the spring 31G is overcome, the valve 31E opens the fuel outlet pipe 31B by pushing up the diaphragm 31D, whereby the fuel is returned to the cylinder 10.

On the other hand, if the pressure of the supplied fuel does not overcome the elastic force of the spring (31G), the diaphragm (31D) can not be pushed up, the valve 31E maintains the fuel outlet pipe (31B) closed fuel supply line The pressure of the fuel in (20) is kept constant.

For example, if the elasticity modulus of the spring 31G is set so that the valve 31E can be pushed up when the fuel pressure in the fuel supply line 20 is 5 Bar or more (the current LPI mass production model is set to 5 Bar). When the pressure of the fuel flowing into the fuel inlet 31C is 5 Bar or more, the valve 31E opens the fuel outlet pipe 31B and the fuel is returned to the cylinder 10.

However, when a fuel pressure of less than 5 Bar is applied to the fuel inlet 31C, the valve 31E closes the fuel outlet pipe 31B so that fuel is not returned to the cylinder 10.

The most common type of failure of the pressure regulating valve 31 having the above-described structure is an open-suck due to a failure of the spring 31G or an O-ring (31L) that seals the high pressure part and the low pressure part. .

As described above, when the sealing failure due to the opening of the valve due to the failure of the spring or the breakage of the O-ring occurs, the pressure of the fuel line is reduced, and thus the engine unstable due to the lack of fuel injection amount injected into the engine. The phenomenon of starting off occurs.

In addition, in the case of the fuel pressure sensor disposed on the fuel return line and detecting the pressure of the fuel line, the pressure of the fuel line is measured and transmitted to the electronic control unit, and the electronic control unit controls the injector by correcting the injection fuel amount based on this signal. Done.

That is, the higher the pressure is the reference to control the fuel injection time is reduced.

In the case of a fuel pressure sensor that plays an important role in such fuel injection, troubleshooting needs to monitor not only disconnection and short-circuit but also whether the value of the sensor is properly output.

This is to determine the horizontal direction in which the difference between the model pressure value calculated from the fuel temperature sensor and the fuel composition and the current sensor output value is maintained within a constant value (ΔP = 4 bar).

In other words, if the difference is maintained for a predetermined time or more than the set constant value (ΔP = 4 bar), the electronic control unit determines that the pressure sensor is an error.

In a conventional Elpia vehicle, when a failure occurs due to an open fixation of a pressure control valve or a breakage of an O-ring, and a pressure drop in a fuel line occurs, there is a problem in that it is determined that the pressure sensor is not a failure of the pressure control valve.

That is, if the output value of the fuel pressure sensor is detected as the difference between the model value, which is the value of the normal state, and the occurrence of a difference more than the set value (4 bar) continues, the electronic control unit is not the failure of the pressure control valve but the failure of the fuel pressure sensor. It was determined that the error code and the error code was outputted.

In addition, when the fuel pressure sensor detects an error, the fuel pressure is recognized as a model value rather than a measured value (lymph groove mode), and thus a much higher fuel pressure is applied compared to the actual pressure, thereby substantially reducing fuel injection amount. Oxygen sensor failure false detection caused by the air-fuel ratio lean phenomenon due to insufficient fuel injection amount is also generated.

For example, if the actual pressure is 4bar due to a failure of the pressure regulating valve but the value calculated by the fuel temperature and composition is 9bar, the electronic control unit recognizes the failure of the fuel pressure sensor.

In addition, the actual pressure value is applied to the model value rather than the 4bar of the sensor output is applied to the injector injection correction for 9bar is to cause a lack of injection amount and eventually the oxygen sensor false sense by the lean mixer is also generated.

In particular, in the case of starting off due to lack of fuel amount without any fault code, there is a problem of over-maintenance to replace even a part without failure because the cause of the starting off is unknown.

The present invention has been invented to solve the above problems, the purpose of which is to determine the air-fuel ratio control value by reading the feedback signal of the oxygen sensor disposed in the exhaust system of the pressure control valve of the parts provided in the fuel line of the vehicle Elpia In the event of a failure of the pressure sensor, it is possible to prevent the detection of faults so as to prevent false detection of sensors or valves in normal operation.

The present invention for realizing the above object comprises the steps of determining whether the Elpia satisfies the preconditions for the fuel gauge diagnosis when the engine of the vehicle maintains the starting on; Checking a temperature criterion for determining whether the coolant temperature and the fuel temperature are equal to or greater than a reference value and fuel stabilization is maintained when the prerequisites for the fuel system diagnosis are satisfied; Setting a fuel model pressure if the temperature criterion is satisfied; If the fuel model pressure is set, extracting the pressure difference through monitoring comparing the measured pressure and the model pressure measured in the fuel line; Determining whether a load condition satisfies a fuel gauge monitoring condition when the extracted pressure difference is equal to or greater than a set reference value; Checking the air-fuel ratio control value from the signal detected by the feedback by the oxygen sensor when the load condition satisfies the fuel gauge monitoring; It provides a fuel gauge monitoring method for an Elpia vehicle, comprising the step of determining whether the pressure control valve or the fuel pressure sensor failure according to the result of the confirmation of the air-fuel ratio control value.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Since the system of the Elpia vehicle according to the present invention is the same or similar to the structure mentioned in the prior art, a detailed description thereof will be omitted and only the monitoring operation of the fuel system will be described with reference to FIG. 3.

The electronic control unit judges the engine speed detected by the crank angle sensor and checks whether the current engine speed maintains the engine starting reference value, for example, 500 RPM or more (S101) to determine whether the engine is currently being started on. It is determined (S102).

If the current engine is in the state of maintaining the start-up in the determination of S102 to determine the conditions of the overall driving state of the vehicle (S103) to determine whether the fuel system diagnostic conditions are satisfied (S104).

The fuel system diagnostic condition is that there is no error in the fuel pressure sensor disposed in the fuel line, the oxygen sensor disposed in the fuel temperature sensor exhaust system, and the fuel pump disposed in the cylinder, and the LPG switch which cuts off the fuel supply to the fuel line includes: It is an off state and it is a condition which keeps the temperature of a fuel and the temperature of a cooling water more than the set reference value.

When the fuel system diagnostic condition is satisfied in the determination of S104, various temperature conditions are checked (S105) to determine whether the temperature condition is satisfied (S106).

The various temperature conditions are conditions in which the temperature of the coolant detected by the water temperature sensor is greater than or equal to the set reference value, and the temperature of the fuel detected by the fuel temperature sensor disposed in the fuel line is greater than or equal to the set reference value, and the temperature of the fuel is stabilized.

The determination of the stabilization conditions of the fuel temperature is calculated by calculating the average value of the fuel temperature as shown in Equation 1 below, and comparing the continuous average temperature difference as shown in Equation 2 below, and confirming that the average temperature difference is included within the set reference value fuel Determine whether the temperature is stabilized.

 T_GAS_AVG = ΣT_GASi / N, where (i = 1 to N)

 ΔT_GAS_AVG = T_GAS_AVG_2-T_GAS_AVG_1

As a result of the determination in S106, when the temperature condition is satisfied, the fuel model pressure is set by applying the pressure of the pressure regulating valve, the saturation vapor pressure for the fuel temperature, and the fuel composition (S107).

When the fuel model pressure is set in S107, the actual fuel pressure measured in the fuel line is compared with the fuel model pressure set in S107 (model pressure-measured pressure) to perform fuel pressure monitoring to extract a pressure difference (S108). .

The pressure difference extracted through the monitoring of the fuel pressure is compared with the set reference value to determine whether the extracted pressure difference exceeds the set reference value (S109).

When the pressure difference exceeds the set reference value in the determination of S109, the engine load, that is, the fuel consumption is checked (S110) to determine whether the load condition is satisfied (S111).

The confirmation of the engine load is confirmed in a condition in which the fuel demand is included in a range of a minimum reference value and a maximum reference value or less in a condition that is not a deployment (WOT) section.

When the load condition is satisfied in the determination of S111, the air-fuel ratio control value is checked from the oxygen sensor disposed in the exhaust system (S112), and it is determined whether the air-fuel ratio control value is kept above the forward reference value (S113).

If it is determined in S113 that the air-fuel ratio control value maintains the forward reference value or more, the electronic control unit determines that the pressure regulating valve has failed (S114), and increases the error counter for the failure determination (S115).

It is determined whether the error counter is countered to the set maximum value in the failure determination (S116). If it is not determined that the error counter is countered to the set maximum value, the process returns to the process of S108, and the error counter is countered to the set maximum value. If it is, the speed of the fuel pump is fixed, preferably at 4 of 5 speeds (S117). After determining that the pressure control valve is in error, the warning lamp lights up and the error code for the failure of the pressure control valve is self-diagnosed. Store in the memory (S118).

However, if the air-fuel ratio control value detected from the oxygen sensor arranged in the exhaust system is not greater than the forward reference value in the determination of S113, it is determined whether the air-fuel ratio control value is less than the negative reference value (S119).

If the air-fuel ratio control value is less than the negative reference value in the determination of S119, the electronic control unit determines that the fuel pressure sensor has failed (S121), and increases the error counter for the failure determination (S122).

Then, it is determined whether the error counter for the failure determination is countered to the set maximum value (S123). If the error counter is not countered to the set maximum value, the process returns to the process of S108, and the error counter is set to the set maximum value. If it is countered, enter the failure mode to fix the fuel pressure to the model pressure (S124).

After determining that the fuel pressure sensor is in error, the warning lamp is turned on and the error code for the failure of the fuel pressure sensor is stored in the self-diagnosis memory (S125).

In addition, when the condition of the engine load is not satisfied in the determination of S111, that is, in the throttle development section in which the fuel injection amount is not large due to the large amount of fuel injection, the error counter is maintained without performing an operation for detecting the fuel gauge error. In step S108 is returned to (S120).

In addition to the above description, when the fuel pressure is actually lowered due to a failure of the pressure regulating valve, the electronic control means richly controls the air-fuel ratio due to insufficient fuel amount.

Therefore, the feedback value detected from the oxygen sensor disposed in the exhaust system is determined to be controlled in the forward direction.

On the contrary, when the fuel pressure is output small due to the failure of the fuel pressure sensor, the electronic control means corrects the fuel pressure, thereby controlling excessive fuel injection in preparation for the actual injection amount.

Therefore, the feedback value detected from the oxygen sensor disposed in the exhaust system is determined by the control in the negative direction.

Therefore, when feedback monitoring the signal detected by the oxygen sensor disposed in the exhaust system it is possible to detect which part of the fuel system is broken.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible.

As described above, the present invention analyzes the feedback value of the air-fuel ratio control signal detected by the oxygen sensor disposed in the exhaust system in the vehicle, and more precisely diagnoses the failure of a plurality of components disposed in the fuel system. By controlling in accordance with the limp home mode, Elpia provides stability and reliability to the running of the vehicle.

Claims (9)

If the engine of the vehicle is in the state of Elpia, the fuel pressure sensor and fuel temperature sensor arranged in the fuel line, the oxygen sensor arranged in the exhaust system, and the fuel pump arranged in the cylinder are free of errors. Determining whether the LPG switch that cuts off the fuel supply is turned off, and satisfies a precondition for diagnosis of a fuel system, the fuel temperature and the temperature of the cooling water being set at a condition of maintaining a predetermined reference value or more; Checking a temperature criterion for determining whether the coolant temperature and the fuel temperature are equal to or greater than a reference value and fuel stabilization is maintained when the prerequisites for the fuel system diagnosis are satisfied; Setting a fuel model pressure if the temperature criterion is satisfied; If the fuel model pressure is set, extracting the pressure difference through monitoring comparing the measured pressure and the model pressure measured in the fuel line; Determining whether a load condition satisfies a fuel gauge monitoring condition when the extracted pressure difference is equal to or greater than a set reference value; Checking the air-fuel ratio control value from the signal detected by the feedback by the oxygen sensor when the load condition satisfies the fuel gauge monitoring; And determining a failure of the pressure regulating valve or the fuel pressure sensor according to the checking result of the air-fuel ratio control value. delete The method of claim 1, The determination of whether the fuel stabilization is to calculate the average value of the fuel temperature, by comparing the continuous average temperature difference, to determine whether the average temperature difference is included within the set reference value fuel gauge monitoring method of an Elpia vehicle. The method of claim 1, The fuel model pressure is set by applying a saturated vapor pressure to the pressure, the fuel temperature and the fuel composition by the pressure regulating valves. The method of claim 1, The determination of the engine load condition is to determine whether the fuel injection amount is a throttle development section in which a fuel pressure drop occurs, and in this section, fuel system monitoring is prohibited. The method of claim 1, If the air-fuel ratio control value detected from the oxygen sensor is equal to or greater than the forward reference value, it is determined that the pressure regulating valve has failed and the error counter is increased. When the error counter is increased to the set maximum value, the fault code output storage and the lamp of the pressure regulating valve are turned on. A fuel system monitoring method for an Elpia vehicle, characterized in that the control. The method of claim 1, If the air-fuel ratio control value detected from the oxygen sensor is equal to or greater than the negative reference value, it is determined that the fuel pressure sensor is faulty and the error counter is increased. When the error counter is increased to the set maximum value, the fault code output storage and the lamp of the fuel pressure sensor are increased. A fuel gauge monitoring method for an Elpia vehicle characterized by controlling lighting. The method of claim 6, If the failure of the pressure control valve is determined to enter the limp home mode, the fuel gauge monitoring method for an Elpia vehicle, characterized in that the fixed control of the speed of the fuel pump. The method of claim 7, wherein If it is determined that the failure of the fuel pressure sensor enters the lymph groove mode, and set the fuel pressure to the model pressure to apply the fuel injection amount control, characterized in that the fuel gauge monitoring of the Elpia vehicle.

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