Procedure for diagnosing a purge control solenoid valve (PCSV)

Abstract

A method for diagnosing a purge control solenoid valve (PCSV), comprising: Creating a negative pressure in a fuel tank (S10); Checking a pressure in the fuel tank and determining whether a target negative pressure is generated (S20); Suspecting blockage of the PCSV electrically controlling an inflow amount of evaporated gas from the fuel tank to an intake system of an engine when it is determined that the target negative pressure is not formed based on a result of determining whether the target negative pressure is formed (S30); and Increasing a purge volume of the PCSV (S40).

Description

[0001] The invention relates to a method for diagnosing a purge control solenoid valve (PCSV) which controls an inflow amount of evaporative gas between an intake system of an engine (e.g., an internal combustion engine) and a canister.

[0002] An internal combustion engine that uses gasoline generates evaporation gas due to the nature of gasoline. This evaporation gas mainly consists of hydrocarbon (HC) components, which are a constituent of harmful gases. Therefore, if the evaporation gas is released into the atmosphere, it can be a major cause of environmental pollution, so every country regulates such evaporated HC gas by law.

[0003] In the related art, the vaporized HC gas is sucked into a suction absorber and then flows back into an engine to be recycled for use as fuel, and a purge control solenoid valve (PCSV) is provided between an intake system of the engine and a canister as a component of a fuel tank to electrically control an inflow amount of the vaporized HC gas when the vaporized HC gas flows into the engine due to a negative pressure.

[0004] An engine electronic control unit (ECU) controls a vaporized HC gas recirculation device to recirculate the vaporized HC gas as long as there is no load on the engine operation. The PCSV plays an important role in an engine control system by collecting the vaporized HC gas generated as a result of fuel evaporation and flowing out of the sealed fuel tank into a canister and then recirculating the collected vaporized HC gas. It thus enforces on-board diagnostic (OBD) regulation to diagnose a failure or jamming (jamming or sticking) of the PCSV. If an open circuit or short circuit occurs, it can be measured by a self-diagnosis resistor of the PCSV, but complicated calculations must be performed if the jamming occurs in an open or closed state.

[0005] Such a diagnosis on components of an evaporative system is performed under the assumption that the fuel tank is sealed, however, if a leak occurs in the evaporative system, the vaporized HC gas is released into the atmosphere, so that a regulation value with respect to the vaporized HC gas is inevitably exceeded.

[0006] Likewise, since the vessel collects only a reasonable amount of the vaporized HC gas, a thorough vessel purge should be performed using the PCSV.

[0007] Fig. Figure 1 is a schematic showing an evaporative gas leak monitoring system, and PCSV diagnosis is performed while monitoring a leak of an evaporative sealing system.

[0008] With reference to Fig. 1, a canister is configured to collect vaporized HC gas generated in a fuel tank, and may include a canister closing valve (CCV) provided between the atmosphere and the canister and having a normally open structure, and when it is determined that a leak of the vapor sealing system occurs, the CCV is closed, and a sealed state is then diagnosed.

[0009] Here, when the PCSV arranged in the intake system of the engine is open, the vaporized HC gas collected in the canister is returned by a negative pressure in the engine in the form of gas, which is sucked into the engine.

[0010] In addition, a fuel tank pressure sensor FTPS is arranged as a detector configured to diagnose the evaporative sealing system.

[0011] Fig. Figure 2 is a diagram showing a method for monitoring an evaporative gas leak. Referring to Fig. 2, with respect to a shut-off blockage of a PCSV, the diagnosis of the shut-off blockage of the PCSV is performed during the monitoring of a leakage of an evaporative system, and the monitoring of the leakage of the evaporative system is performed based on a drop in a natural evaporative pressure after a target negative pressure is forcibly formed in the fuel tank.

[0012] That is, the larger a leak size, the larger a monitored waste, so the leak size is measured based on the monitored waste.

[0013] Here, a method of forming a negative pressure in the fuel tank uses the negative pressure of the engine, and at this point, when the CCV is closed and the PCSV is open, the negative pressure is formed in the fuel tank.

[0014] When the PCSV is locked, it does not affect the vacuum in the engine, so no vacuum is formed in the fuel tank and only a slight variation in the pressure in the fuel tank occurs.

[0015] When such a phenomenon occurs, an ECU detects a PCSV locking failure.

[0016] In the related art, foreign matter is generated in the PCSV in proportion to a travel distance of a vehicle due to the characteristic of an internal combustion engine thereof, and accumulated by a chemical reaction of the internal combustion engine between carbon or a fuel component and a fuel hose. The accumulated foreign matter is mixed with fuel to produce a fluid having a viscosity. These fluid components are hardened due to icing during an overnight hold, so that an event occurs in which the PCSV is held by pressure so that it cannot be opened when operated even at the same operating time (i.e., the same purge amount).

[0017] However, when a temperature rises to thaw such foreign matter with viscosity, the PCSV operates normally again, and therefore, when such a series of processes as described above is repeated, an engine warning light will eventually turn on.

[0018] In fact, in the case where the engine warning light is on, replacement of the PCSV is often carried out, and as a result of such fault diagnosis resulting from the blockage of the PCSV, high costs are incurred.

[0019] Furthermore, when an outside temperature is low, the foreign matter with viscosity also causes an icing problem, which is a big problem for a manufacturer.

[0020] When a discharge amount of the PCSV is increased during the formation of negative pressure in an engine, the viscosity of the foreign matter is overcome to form the negative pressure and solve the problems described above, but there is a limitation in increasing the discharge amount.

[0021] In the mixture flowing into the PCSV, fuel and air are mixed, and since the prediction of instantaneous engine control that accurately controls the fuel is very difficult, if an excessive mixture flows into the PCSV to drive the engine, safety problems such as start-up or the like may be caused.

[0022] When such an excessive mixture flows into the PCSV, an oxygen molecule (O 2 ) detector detects a fuel quantity of the excessive mixture, but the problems described above occur before the O 2 -Detector learns the amount of fuel.

[0023] US 2014 / 0 130 781 A1 discloses a method for diagnosing a purge control solenoid valve (PCSV), comprising: creating a negative pressure in a fuel tank; checking a pressure in the fuel tank and determining whether a target negative pressure is generated; and presuming blockage of the PCSV electrically controlling an inflow of vaporized gas from the fuel tank to an intake system of an engine if, based on a result of determining whether the target negative pressure is generated, it is determined that the target negative pressure is not generated. Another method for diagnosing a purge control solenoid valve (PCSV) is known from DE 195 18 292 A1.

[0024] The object of the invention is to provide a method for diagnosing a purge control solenoid valve (PCSV) configured to diagnose a lock-up condition and a fault condition of the PCSV to correct a temporary lock-up thereof, so that safety problems such as engine start-up and the like are prevented and also unnecessary maintenance and replacement are not required.

[0025] Other objects of the invention will become apparent from the following description and will be apparent with reference to the exemplary embodiments of the invention. Likewise, it will be apparent to those skilled in the art that the objects and advantages of the invention may be realized by the means as claimed and combinations thereof.

[0026] These objects are achieved by a method for diagnosing a purge control solenoid valve (PCSV) according to claim 1. Further developments are the subject of the dependent claims.

[0027] According to the invention, a method for diagnosing a purge control solenoid valve (PCSV) comprises: forming a negative pressure in a fuel tank, checking a pressure in the fuel tank and determining (or determining or ascertaining) whether a target negative pressure is generated, suspecting blockage (or jamming or sticking) of the PCSV electrically controlling an inflow amount of evaporated gas from the fuel tank to an intake system of an engine (e.g., an internal combustion engine) when it is determined that the target negative pressure is not formed based on the result of determining whether the target negative pressure is generated, and increasing a purge amount of the PCSV.

[0028] If it is determined that the target negative pressure is formed based on the result of determining whether the target negative pressure is generated, the PCSV can be diagnosed as normal.

[0029] The formation of the negative pressure in the fuel tank may block a canister closure valve provided in a canister that resupplies (or recirculates or recirculates) the vaporized gas of the fuel tank and open the PCSV to form the negative pressure in the fuel tank.

[0030] The method may further include determining whether the negative pressure is formed in the fuel tank after the purge amount is increased to a target purge amount by increasing the purge amount of the PCSV.

[0031] If it is determined that the target negative pressure is not formed after increasing the purge amount of the PCSV based on the result of determining whether the negative pressure is formed in the fuel tank, the PCSV may be diagnosed as a close lock failure.

[0032] The target purge amount may increase an operation time (or duty cycle or discharge) to more than that before increasing the purge amount of the PCSV, and a reference value of the increased operation time may specify an operation time value configured to have a maximum electromotive force of a PCSV according to the characteristic thereof, and may be a value improved in a range of 25% to 35% based on the PCSV used in diagnosis.

[0033] After increasing the purge volume of the PCSV, the PCSV can be closed.

[0034] The method may further comprise, after increasing the purge amount of the PCSV, stopping an operation of the PCSV when it is determined that the target negative pressure is formed based on the result of determining whether the negative pressure is formed in the fuel tank.

[0035] Before stopping the increase in the purge volume of the PCSV, a flip-flop circuit (or flip-flop) is used to maintain the increased purge volume of the PCSV.

[0036] The purge amount of the PCSV can be increased according to a purge amount increased map, wherein the purge amount increased map can be set to a 2-dimensional map, and a purge discharge amount (purge operating time) can be determined by the negative pressure in the engine and the characteristic of the PCSV.

[0037] An accumulated flush volume configured to be diagnosed as a PCSV failure can be reduced to 0.6 kilograms (kg) / hour (h) or less.

[0038] The invention is explained in more detail with reference to the drawing. The drawing shows: Fig. 1 is a diagram illustrating a system for monitoring an evaporative gas leak; Fig. 2 is a diagram illustrating a method for monitoring an evaporative gas leak; Fig. 3 is a diagram illustrating a method for diagnosing a purge control solenoid valve (PCSV) according to an exemplary embodiment of the invention; Fig. 4 is a diagram for describing the method for diagnosing a purge control solenoid valve (PCSV) according to an exemplary embodiment of the invention; Fig. 5 is a diagram showing a monitoring result with respect to a PCSV which is in a temporary blocking state according to the invention; Fig. 6 is a diagram showing a monitoring result with respect to a PCSV which is in a blocking state according to the invention; and Fig. 7 is a diagram showing a leak monitoring result according to the invention.

[0039] It should be understood that the attached drawings are not necessarily to scale and present a somewhat simplified representation of various features illustrating the basic principles of the invention. The specific design features of the present invention, including, for example, specific dimensions, orientations, positions, and shapes disclosed herein, will be determined in part by the particular intended application and usage environment.

[0040] In the figures, reference numerals refer to the same or equivalent parts of the present invention throughout the individual figures of the drawing.

[0041] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention has been described in connection with exemplary embodiments, it is to be understood that the present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments which may be included within the scope of the invention as defined by the appended claims.

[0042] Reference may be made to the accompanying drawings which show exemplary embodiments of the invention and to the description of the drawings in order to fully understand the invention, the advantages of the operation of the invention and the objects achieved by the practice of the invention.

[0043] In various exemplary embodiments, known technologies or detailed descriptions may be reduced or omitted to avoid unclear evaluation of the disclosure by those skilled in the art.

[0044] Fig. 3 is a diagram illustrating a method for diagnosing a purge control solenoid valve (PCSV) according to an exemplary embodiment of the invention, and Fig. 4 is a diagram for describing the method for diagnosing a purge control solenoid valve (PCSV) according to an exemplary embodiment of the invention.

[0045] The following is based on the Fig. 3 and Fig. 4 describes a method for diagnosing a purge control solenoid valve (PCSV) according to an exemplary embodiment of the invention.

[0046] As described above, there is a limitation in increasing a discharge amount and responding to a PCSV lock-up to cause a result in which the time for fault diagnosis is increased.

[0047] Accordingly, according to the invention, as in Fig. 4, a PCSV diagnosis is divided into two stages and a collected air amount is additionally increased, and when a PCSV closing blockage is suspected in a first stage, a purge discharge amount (purge operation time) is increased to determine whether the PCSV closing blockage is an actual blockage or a temporary blockage resulting from carbon deposition and the like.

[0048] First, a canister closing valve (CCV) is blocked and a PCSV is opened (S10) to create a negative pressure in a fuel tank.

[0049] As such, a tank pressure detector determines whether a target negative pressure is formed in the fuel tank (S20).

[0050] When the target negative pressure is measured based on the detection result (S20), the PCSV can be diagnosed as normal (S21).

[0051] However, when a state is determined based on the determination result (S20) in which the pressure in the fuel tank does not reach the target negative pressure and an atmospheric pressure or a variation in the pressure is small, it is presumed that a recoverable blocking state of the PCSV occurs, rather than directly diagnosing the state as a blocking of the PCSV (S30).

[0052] In the typical diagnosis of PCSV blocking, when the pressure in the fuel tank is equal to an atmospheric pressure in an initial stage of forming the target negative pressure at the start of opening of the PCSV, this is diagnosed as the PCSV blocking.

[0053] Such a typical diagnosis is used as a first-stage diagnosis in an exemplary embodiment of the invention, so that when the pressure in the fuel tank is equal to the atmospheric pressure and the negative pressure is not generated in the engine in the first-stage diagnosis, a purge amount is added to perform a failure diagnosis.

[0054] As shown in the figure, a diagnostic area is enlarged to increase the purge amount to a target amount (S40). When the purge discharge amount is increased, an operating time that overcomes the viscosity due to carbon is generated at any point. At this point, the PCSV is determined to be normal.

[0055] That is, in a second-stage diagnosis after the first-stage diagnosis, there is a pressure behavior equal to atmospheric pressure, and a blockage is removed at any point, so that an abrupt pressure drop with a normal behavior is generated.

[0056] As described above, after the purge amount is increased, it is again determined whether the negative pressure is formed in the fuel tank (S50), and if it is determined that the target negative pressure cannot be formed even if the purge amount is increased, a PCSV lock failure is diagnosed (S51), whereas if it is determined that the target negative pressure can be formed after the purge amount is increased, a temporary PCSV lock is determined.

[0057] In addition, when the increased purge amount reaches the target amount, the PCSV is closed, and when the PCSV is closed, the pressure in the fuel tank gradually increases as shown in the drawing.

[0058] As described above, in the case of increasing the purge amount when the PCSV is in an actual close-lock state, almost no mixture can flow into the engine even if the purge amount is increased, so that driving of the engine cannot be effected, and an actual amount of the mixture flowing into the engine can be reduced compared with a PCSV which is not in the actual close-lock state due to narrowing of a flow path by foreign matter.

[0059] Likewise, once an operation time that overcomes a certain viscosity is generated and after operation of the PCSV, the negative pressure in the fuel tank can form normally.

[0060] Fig. 5 is a diagram showing a monitoring result with respect to a PCSV which is in a temporary blocking state according to the invention.

[0061] Referring to the drawing, the PCSV in which a range error is generated does not actually work, and Fig. Figure 5 shows that a blockage of the PCSV is recovered after an overnight hold at an outside temperature of 10°C.

[0062] Meanwhile, when a temporary PCSV blockage is detected due to the increased purge amount, the operation of the PCSV is stopped (S70) by reducing the increased purge amount again, but before reducing the increased purge amount, there is a need to use a flip-flop circuit (S60).

[0063] When the increased purge amount is immediately reduced during the previous increase of the purge amount to form the pressure in the fuel tank as the negative pressure, a large leakage error is generated, so that the flip-flop can be set to maintain the increased purge amount.

[0064] That is, as in Fig. As shown in Figure 6, the above-described problems are solved by maintaining the increased purge amount after increasing the purge amount until the diagnosis is completed to achieve the target purge amount, which is improved in a range of 25% to 35%. To avoid an abrupt increase in the purge amount to maintain vehicle idling, a two-dimensional map of the increased purge amount is set and mapped according to the negative pressure in the engine and the characteristics of the PCSV so as not to cause a problem in driving the engine.

[0065] Likewise, to ensure a time to overcome the blockage of the PCSV, a condition for a reduced accumulated flush volume is more preferred than a typical condition for it.

[0066] That is, as in Fig.7, when an accumulated purge amount is equal to 0.6 kg / h based on a failure judgment result, the pressure in the fuel tank reaches a failure diagnosis pressure, so that an accumulated purge amount diagnosed as a failure is preferably reduced to 0.6 kg / h or less to allow the purge amount to be increased above the failure diagnosis pressure.

[0067] However, the accumulated purge amount may vary according to the vehicle and an engine displacement thereof, so that it is changeable in a form of a map parameter.

[0068] According to exemplary embodiments of the invention, it is possible to increase the purge amount of the PCSV by determining a condition of the PCSV by presuming the blocking of the PCSV to recover from the blocking of the PCSV, instead of immediately diagnosing the PCSV as a PCSV blocking failure in the case of determining that the pressure in the fuel tank does not reach the target negative pressure based on the measurement result of the tank pressure detector when diagnosing the PCSV.

[0069] Accordingly, when the PCSV is in a temporary lock-out state, the temporary lock-out state is released by increasing the purge amount of the PCSV, so that losses due to fault diagnosis and maintenance can be reduced.

[0070] For ease of explanation and accurate definition of the appended claims, the terms "top", "bottom", "inside", "outside", "front", "rear", etc., are used to describe the features of the exemplary embodiments with reference to the positions of those features as shown in the figures.

Claims

[1] A method for diagnosing a purge control solenoid valve (PCSV), comprising: Creating a negative pressure in a fuel tank (S10); Checking a pressure in the fuel tank and determining whether a target negative pressure is generated (S20); Suspecting blockage of the PCSV electrically controlling an inflow amount of evaporated gas from the fuel tank to an intake system of an engine when it is determined that the target negative pressure is not formed based on a result of determining whether the target negative pressure is formed (S30); and Increasing a purge volume of the PCSV (S40). [2] The method according to claim 1, wherein, based on the result of determining whether the target negative pressure is generated, when it is determined that the target negative pressure is formed, the PCSV is diagnosed as normal (S21). [3] The method of claim 1 or 2, wherein forming the negative pressure in the fuel tank blocks a canister closure valve provided in a canister that resupplies the vaporized gas of the fuel tank and opens the PCSV to form the negative pressure in the fuel tank. [4] Method according to one of claims 1 to 3, further comprising: Determine whether the negative pressure is formed in the fuel tank after the purge amount is increased to a target purge amount by increasing the purge amount of the PCSV (S50). [5] The method according to claim 4, wherein, based on the result of determining whether the negative pressure is formed in the fuel tank, it is determined that the target negative pressure is not formed after increasing the purge amount of the PCSV, the PCSV is diagnosed as a close lock failure (S51). [6] The method according to claim 4 or 5, wherein the target purge amount has a value which is improved in a range of 25% to 35% above that before increasing the purge amount of the PCSV. [7] Method according to one of claims 4 to 6, wherein after increasing the purge volume of the PCSV, the PCSV is closed. [8] Method according to one of claims 4 to 7, further comprising: Stopping the increase of the purge amount of the PCSV when it is determined that the target negative pressure is formed by increasing the purge amount of the PCSV based on the result of determining whether the negative pressure is formed in the fuel tank (S70). [9] The method according to claim 8, wherein before stopping the increase of the purge amount of the PCSV, a flip-flop circuit is used to maintain the increased purge amount of the PCSV (S60). [10] The method according to any one of claims 1 to 9, wherein the purge amount of the PCSV is increased according to a map of the increased purge amount, and wherein the map of the increased purge amount is set to a 2-dimensional map. [11] The method of claim 10, wherein an accumulated purge amount configured to be diagnosed as a failure of the PCSV is reduced to 0.6 kilograms (kg) / hour (h) or less.

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