KR101483645B1 - Apparatus and method for diagnosis high pressure pump of gasoline direct injection engine - Google Patents

Abstract

In the GDI (Gasoline Direct Injection) engine, the TDC (Top Dead Center) of the high-pressure pump is learned during cranking for starting the engine and the TDC learning value of the high-pressure pump is used to follow the target pressure The cause of the failure is to make a clear diagnosis.

The present invention relates to a method for determining whether TDC learning condition of a high-pressure pump is satisfied when cranking of an engine is detected, asynchronously controlling a control valve when TDC learning condition of a high-pressure pump is satisfied, Determining a TDC learning value of the high-pressure pump as a closing timing of the control valve; and determining an error of the closing timing of the control valve as a determination And determining a pump lobe phase error or target pressure tracking error according to the high pressure pump TDC learning value.

GDI engine, high pressure pump diagnosis, TDC learning, asynchronous control, pressure change, error judgment

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a high-

More particularly, the present invention relates to a GDI (Direct Injection) engine, which learns the TDC (Top Dead Center) of a high-pressure pump during engine starting and uses a TDC learned value of a high- The present invention relates to a high-pressure pump diagnostic apparatus and method of a GDI engine which makes it possible to clearly diagnose a cause that can not be followed.

Currently, gasoline engines that are mass-produced are classified into a PFI (Port Fuel Injection) engine that injects fuel into the combustion chamber before the intake valve, and a GDI (Gasoline Direct Injection) engine that injects fuel directly into the combustion chamber.

1 is a schematic view of a fuel system of a general GDI engine.

The fuel system of the GDI engine is equipped with a low pressure pump 11 operated as a motor for supplying fuel to the fuel rail 40 in the fuel tank 10 and a high pressure pump 30 operated by the camshaft And is mounted on the cover 20.

An injector 41 for injecting the calculated amount of fuel into each combustion chamber is mounted and the pressure inside the fuel rail 40, that is, the pressure of fuel injected to each injector 41 is detected at the end of the fuel rail 40 A pressure sensor 42 is mounted.

Therefore, the fuel supplied from the fuel tank 10 to the engine by the operation of the low-pressure pump 11 is pressurized to a predetermined pressure set by the high-pressure pump 30 operated by the camshaft to about 120 bar, .

At this time, the pressure sensor 42 mounted at the end of the fuel rail 40 detects the pressure formed on the fuel rail 40 and applies it to the engine control means not shown.

Therefore, the engine control means performs the fuel pressure feedback (feed back) control so as to maintain the optimum pressure according to the operating condition.

2 is a view showing a structure of a high-pressure pump applied to a fuel system of a general GDI engine.

The high pressure pump 30 includes a plunger 31, a pump lobe 60 integrally formed with the camshaft, a control valve 32, and a solenoid 33.

The high pressure pump 30 is a positive displacement pump in which the plunger 31 presses the fuel while reciprocating up and down according to the operation of the pump lobe 60. The maximum discharge flow rate per stroke corresponds to the volume trajectory created by the plunger 31 do.

Since the fuel is delivered only when the control valve 32 is closed, the engine control means (not shown) controls the discharge amount of the fuel by adjusting the closing time of the control valve 32 through the solenoid 33.

For example, when the target fuel pressure is determined in the specific operating condition determined by the engine speed and the load, the engine control means, not shown, adjusts the closing time of the control valve 32 via the solenoid 33, (40) is feedback-controlled so as to form a target fuel pressure.

In order to maintain the fuel pressure formed in the fuel rail 40 at the target fuel pressure determined according to the operating condition, the fuel is continuously supplied through the operation of the high-pressure pump 30 by the amount of fuel injected into the injector 41.

If the supply amount through the high-pressure pump 30 exceeds the injection amount by the injector 41, the pressure inside the fuel rail 40 is raised, and in the opposite case, the pressure inside the fuel rail 40 is reduced.

Therefore, the engine control means adjusts the closing timing of the control valve 32 mounted on the high-pressure pump 30 in accordance with the pressure of the fuel rail 40 detected through the pressure sensor 42, Maintain fuel pressure at all times.

3, the closing timing of the control valve 32 is controlled in order to adjust the fuel discharge amount during the operation of the high-pressure pump 30 by the camshaft. In the compression stroke of the high-pressure pump 30, The discharge amount of the fuel increases as the closing timing (t1, t2, t3) of the high-pressure pump (32) precedes the TDC of the high-pressure pump (30).

The section during which the actual fuel is pumped has a period from the closing timing of the control valve 32 to the high-pressure pump TDC during the compression of the high-pressure pump 30 by the camshaft, that is, Δt1, Δt2 and Δt3.

In the high pressure pump learning method applied to the conventional GDI engine, a method of filtering the integral control value at the closing timing of the control valve for matching the target fuel pressure under specified conditions and storing it as learning value is applied.

Since the above-described conventional learning method is an outline learning of how to change the closing timing of the control valve in order to follow the target fuel pressure, rather than learning about the cause of failing to follow the target fuel pressure, It is impossible to confirm whether the fuel pressure control is abnormally executed or not.

The density of the fuel, the composition ratio of the fuel, the production deviation of the camshaft, and the hardware error of the camshaft affect the learning of the high-pressure pump.

That is, the lower the density of the fuel, the more the amount of fuel must be discharged to maintain the same fuel pressure, so that the learning value becomes a direction away from the compression TDC.

In particular, when the theoretical air / fuel ratio is different from that of gasoline, such as methanol or ethanol, the amount of fuel discharged to maintain the same fuel pressure changes greatly, so the learning value also changes greatly.

Further, since the high-pressure pump is driven by the pump lobe which is integrally formed with the camshaft, when the TDC of the high-pressure pump fluctuates due to machining variation of the pump lobe, the closing timing of the control valve for discharging the same flow rate is changed, It also changes.

If the camshaft with the pump lobe has abrasion or misalignment of the timing belt or chain, the TDC of the high-pressure pump is abnormally opened, so that the closing timing of the control valve is also changed and the learning value is also changed.

However, the conventional high-pressure pump diagnosis method is a method of determining an error when the target fuel pressure can not be followed simply, and therefore, the cause of the problem in the target fuel pressure control can not be known.

Therefore, when an error occurs in the target fuel pressure control, the mechanic must check not only the high-pressure pump but also the mounting state of the camshaft, the state of the timing belt, and the like, so that the maintenance and process ratio occur, And the maintenance cost is incurred.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to learn TDC of a high-pressure pump during engine starting and to clearly diagnose a cause of failure in following a target pressure by using a TDC learning value of a high- will be.

According to an aspect of the present invention, there is provided a high-pressure pump diagnostic apparatus for a GDI engine,

A water temperature sensor for detecting the temperature of the cooling water;

An intake temperature sensor for detecting an air temperature supplied to the combustion chamber;

A pressure sensor for detecting a pressure formed in the fuel rail according to the operation of the high-pressure pump;

A control unit for asynchronously controlling the control valve of the high-pressure pump according to the engine cranking, detecting a change in the fuel pressure thereby learning the TDC of the high-pressure pump, and diagnosing the high-pressure pump by applying the TDC learning value of the high-

A memory unit for storing the high pressure pump TDC learning value and the diagnosis result;

.

In the high-pressure pump diagnosis method of the GDI engine according to the present invention,

(a) determining whether the TDC learning condition of the high-pressure pump is satisfied when cranking of the engine is detected;

(b) asynchronously controlling the control valve when the TDC learning condition of the high-pressure pump is satisfied, and detecting a TDC by detecting a change in the fuel pressure;

(c) determining and storing the TDC learning value of the high-pressure pump by repeating the TDC determination a predetermined number of times and then filtering;

(d) determining a closing timing of the control valve based on the TDC learned value of the high-pressure pump, and determining an error of the control valve closing timing, and determining a pump lobe phase error or a target pressure tracking error according to the high- .

According to the present invention, the TDC of the high-pressure pump is learned by reflecting only the phase difference of the pump lobe without being influenced by the density of the fuel and the composition ratio of the fuel, and the cause of the problem that the target fuel pressure can not be followed clearly So that it is possible to take quick action and to prevent the process cost and the maintenance of erroneous operation.

In addition, when the pump lobe is mounted on the camshaft to which the CVVT (Continuously Variable Valve Timing) is not applied, it is possible to detect the camshaft phase problem by learning the TDC of the high-pressure pump without the cam sensor, .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains.

The present invention can be embodied in various different forms, and thus the present invention is not limited to the embodiments described herein.

5 is a schematic view of a high-pressure pump diagnostic apparatus of a GDI engine according to an embodiment of the present invention.

The present invention includes a water temperature sensor 101, an intake air temperature sensor 102, a pressure sensor 103, a control unit 104, a memory unit 105 and a control valve 106.

The water temperature sensor 101 detects the temperature of the cooling water circulating the engine and provides the control unit 104 with information on the detected temperature.

The intake air temperature sensor 102 detects the temperature of the air supplied to the combustion chamber and provides the control unit 104 with information on the detected temperature.

The pressure sensor 103 is mounted at an end of the fuel rail, detects pressure formed in the fuel rail according to the operation of the high pressure pump, and provides information to the control unit 104 about the detected pressure.

The control unit 104 is sufficiently cooled (Overnight Soaking) after the engine is turned off, so that all the fuel in the fuel line and the fuel rail are returned to the fuel tank so that the pressure of the fuel rail equilibrates with the atmospheric pressure The control valve 106 in the high-pressure pump is asynchronously controlled (closed) to raise the fuel pressure inside the high-pressure pump, and the change in the fuel pressure due to the change To learn the high-pressure pump TDC.

In other words, the fuel pressure rises while starting to pass through the high pressure pump BDC (bottom dead center), and after the TDC, the pressure does not rise any more, so the TDC of the high pressure pump is learned by monitoring the pressure change.

Further, the TDC learning value of the above-described high-pressure pump is used to clearly discriminate whether the camshaft phase is abnormal or causes the compression failure to occur.

The memory unit 105 stores the TDC learning value of the high-pressure pump learned by the control unit 104, and stores the diagnosis result of the camshaft phase as a failure code.

The control valve 106 is mounted on the high-pressure pump 106 and its closing timing is adjusted by a solenoid valve so as to control the fuel discharge amount in accordance with the up-and-down movement of the plunger.

The operation of the present invention including the functions as described above is executed as follows.

In step S101, the GDI engine determines whether starting-on (cranking) is attempted in a state in which the GDI engine maintains the startup-off state (S102).

If the startup of the engine is not started in step S102, the start-up of the engine is continuously waited. If the start-up is attempted, the temperature of the cooling water, the intake temperature and the fuel rail pressure are detected at that time, It is determined whether the learning condition is satisfied (S103).

In order to learn the TDC of the high-pressure pump, there should be no residual pressure on the fuel rail or vapor of vapor.

If the fuel vapor in the vapor phase remains on the fuel rail, there is a problem that the fuel pressure does not increase for a predetermined time even if the high-pressure pump is operated.

Therefore, the TDC learning condition of the high-pressure pump is such that the engine is sufficiently cooled so that the pressure of the fuel rail is in equilibrium with the atmospheric pressure, the temperature of the cooling water at startup is lower than the set reference temperature and the temperature of the air supplied to the combustion chamber at startup Is set to a condition less than the set temperature.

Even when the engine is cooled down due to the high cooling water temperature or the intake air temperature, the temperature of the fuel rail increases due to the temperature of the engine and the pressure inside the fuel rail lowers, so that the fuel pressure becomes lower than the saturated steam pressure. It can evaporate and exist in a vapor state.

If the TDC learning condition of the high-pressure pump is not satisfied in S103, the learning mode is not executed, and if the learning condition is satisfied, asynchronous control is executed to normally close the control valve 106 that is set in the learning mode and mounted in the high- S104).

When the plunger rises according to the operation of the pump lobe integrated with the camshaft in the asynchronous control of the control valve 106 as described above, the fuel pressure inside the high-pressure pump rises and no further pressure rise occurs when passing through the TDC .

Therefore, the control unit 104 reads the information of the pressure sensor 103 mounted on the fuel rail at predetermined intervals of time, preferably at intervals of 1 ms to detect the fuel pressure (S105), calculates the change of the fuel pressure per hour The upward slope of the fuel pressure is calculated (S106).

At this time, since the timing of the first fuel pressure rise depends on the position of the pump lobe at the start-off time, the first fuel pressure rise is excluded from the TDC learning of the high-pressure pump.

It is determined whether the upward slope of the fuel pressure calculated in step S106 has exceeded the set first threshold TH1 in step S107. If the upward slope does not exceed the first threshold TH1, the process returns to step S104. It is determined that the camshaft that operates the high-pressure pump that has exceeded the threshold value TH1 has passed the BDC (S108) and the flag is set (BDC Flag = 1) (S109).

Thereafter, the fuel pressure rising slope is continuously calculated (S110), and it is determined whether the rising slope has decreased to less than the set second threshold value TH2 (S111).

If it is determined in step S111 that the rising slope has not been decreased to less than the second threshold value TH2, the process returns to step S110. If the slope is less than the second threshold value TH2, it is determined that the camshaft has passed the TDC. The TDC of the high-pressure pump is recognized and the flag is set (TDC Flag = 1) (S112).

Thereafter, the TDC progress flag is incremented by a counter (S113), the BDC flag is reset (S114), and then it is determined whether the number of TDC elapsed flags exceeds a set reference number, preferably two times (S115).

The reason why the number of times of the TDC elapsed flag is detected more than the reference number is to filter the noise of the pressure sensor to provide accuracy in the TDC determination of the high-pressure pump.

If the number of times of the TDC elapsed flag exceeds the set reference number, the optimum value is extracted through filtering and stored in the memory unit 105 as the TDC learned value of the high-pressure pump (S116).

The learning value of the high-pressure pump TDC accumulates and reflects existing learning results as shown in Equation (1) below.

High pressure pump TDC learning value N High pressure pump TDC learning value N-1 + K2 Correction coefficient High pressure pump TDC learning value N High pressure pump TDC learning value N-

The high pressure pump TDC learning procedure is executed as shown in the graph of FIG.

The procedure of diagnosing the high-pressure pump by applying the learned TDC value of the high-pressure pump learned through the above procedure will be described with reference to FIG.

The controller 100 detects the closing timing of the control valve 106 by applying the TDC learned value of the high-pressure pump to the control valve 106 (S201), and determines whether the closing timing of the control valve 106 exceeds the set reference time (S202).

If the closing timing of the control valve 106 does not exceed the set reference time in S202, it is determined that the high-pressure pump is normally operated. If the closing timing of the control valve 106 exceeds the set reference time, It is determined to be abnormal and the error counter is incremented (S203).

If it is determined in step S204 that the increased error counter has not exceeded the set number of times, the process returns to step S201. If the set number is exceeded, the TDC learning value of the high-pressure pump is set to the range of the set reference value (S205).

If the TDC learning value of the high-pressure pump is included in the range of the set reference value in the determination of S205, it is not a problem of the camshaft or the pump lobe, but leaks due to wear of the specific components constituting the high- (S206), and the diagnostic code is stored in the memory unit 105 (S208).

If the TDC learning value of the high-pressure pump is not included in the range of the set reference value in the determination of S205, it is determined that the phase is defective due to the abnormality of the camshaft or the pump lobe (S207), and the diagnostic code is stored in the memory unit 105 (S208).

Therefore, the present invention clearly diagnoses the reason why the GDI engine fails to follow the target pressure, thereby preventing the process cost and the erroneous maintenance from occurring.

In particular, when a pump lobe is mounted on a cam that does not have a CVVT, the cam phase can be diagnosed through TDC learning of the high-pressure pump without a cam sensor.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It is included in the scope of right.

1 is a schematic view of a fuel system of a general GDI engine.

2 is a view showing a structure of a high-pressure pump applied to a fuel system of a general GDI engine.

3 is a view showing the operation of the high-pressure pump and the closing timing of the control valve in the fuel system of a general GDI engine.

4 is a schematic view of a high-pressure pump cam shaft phase diagnosis apparatus of a GDI engine according to an embodiment of the present invention.

5 is a flowchart illustrating a high-pressure pump TDC learning procedure of a GDI engine according to an embodiment of the present invention.

FIG. 6 is a graph illustrating the pressure gradient calculation and TDC determination in the high pressure pump TDC learning in accordance with an embodiment of the present invention.

7 is a flowchart illustrating a high-pressure pump camshaft phase diagnosis procedure according to an embodiment of the present invention.

Description of the Related Art

101: water temperature sensor 102: intake air temperature sensor

103: pressure sensor 104:

105: memory unit 106: control valve

Claims (10)

A water temperature sensor for detecting the temperature of the cooling water; An intake temperature sensor for detecting an air temperature supplied to the combustion chamber; A pressure sensor for detecting a pressure formed in the fuel rail according to the operation of the high-pressure pump; A control unit for asynchronously controlling the control valve of the high-pressure pump according to the engine cranking, detecting a change in the fuel pressure thereby learning the TDC of the high-pressure pump, and diagnosing the high-pressure pump by applying the TDC learning value of the high- A memory unit for storing the high pressure pump TDC learning value and the diagnosis result; The high-pressure pump diagnostic device of the GDI engine. The method according to claim 1, The control unit learns the TDC of the high-pressure pump under the condition that the engine is cooled, the pressure of the fuel rail is in equilibrium with the atmospheric pressure, the temperature of the cooling water at startup is less than the set reference temperature, and the temperature of the air supplied to the combustion chamber is lower than the set temperature. And the high-pressure pump diagnosis device of the GDI engine. The method according to claim 1, Wherein the controller learns the TDC by repeating the change in the fuel pressure more than the predetermined number of times while the high-pressure pump control valve is asynchronously controlled. The method according to claim 1, The control unit judges the closing timing of the control valve by the TDC learning value of the high-pressure pump, and when it is determined that the TDC learning value of the high-pressure pump is within the range of the reference value, it is determined that the leakage due to the wear of the specific component , The high-pressure pump diagnosis device of the GDI engine judging that the leak of the fuel line is defective. The method according to claim 1, If the TDC learning value of the high-pressure pump is not within the range of the reference value, it is determined that the high-pressure pump cap shaft or the pump lobe is defective. GDI engine's high-pressure pump diagnostic device. (a) determining whether the TDC learning condition of the high-pressure pump is satisfied when cranking of the engine is detected; (b) asynchronously controlling the control valve when the TDC learning condition of the high-pressure pump is satisfied, and detecting a TDC by detecting a change in the fuel pressure; (c) determining and storing the TDC learning value of the high-pressure pump by repeating the TDC determination a predetermined number of times and then filtering; (d) determining a closing timing of the control valve based on the TDC learning value of the high-pressure pump, and determining an error of the control valve closing timing, based on the learning value of the high-pressure pump TDC, determining a pump lobe phase error or a target pressure- Gt; a < / RTI > GDI engine. The method according to claim 6, The TDC learning condition of the high-pressure pump in the process (a) Wherein the engine is cooled, the pressure of the fuel rail is in equilibrium with the atmospheric pressure, and the cooling water temperature and the intake air temperature condition do not cause evaporation of the fuel. The method according to claim 6, The determination of the TDC in the step (b) And when the pressure rising gradient exceeds a first threshold value, it is determined that the BDC has elapsed. If the pressure rising gradient is less than a second threshold value after BDC has elapsed, Pump diagnostic method. The method according to claim 6, The method of claim 1, wherein the TDC learning value of the high-pressure pump is included in the range of the reference value in the step (d). The method according to claim 6, Wherein the pump lobe is determined as a cam phase failure when the TDC learning value of the high-pressure pump is not included in the range of the set reference value in the step (d).

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