KR20200055549A - Method for controlling canister purge system - Google Patents

Abstract

An objective of the present invention is to provide a control method of a canister purge system which can precisely control a purge control valve. According to the present invention, the control method of a canister purge system recognizes whether one of a single-path canister purge system configured to purge evaporation gas only downstream of a throttle valve and a dual-path canister purge system configured to purge evaporation gas downstream of a throttle valve and upstream of a compressor is installed on a vehicle, uses a pressure-based single-purge map to execute a single-purge mode when the single-path canister purge system is recognized, and uses a pressure-based dual-purge map to execute a dual-purge mode when the dual-path canister purge system is recognized. The single-purge mode checks a current purge condition of the single-path canister purge system by the single-purge map, and controls a purge control valve in accordance with the checked current purge condition. The dual-purge mode checks a current purge condition of the dual-path canister purge system by the dual-purge map, and controls a purge control valve in accordance with the checked current purge condition.

Description

Control method of canister purge system {METHOD FOR CONTROLLING CANISTER PURGE SYSTEM}

The present invention relates to a control method of a canister purge system, and more specifically, by sufficiently utilizing the overall pressure information of the intake system using a pressure-based purge map, it is possible to accurately check the purge conditions according to the operating conditions of the engine, and confirm The present invention relates to a control method of a canister purge system capable of precisely controlling a purge control valve according to purge conditions.

The fuel stored in the fuel tank of the vehicle generates evaporation gas as a certain period of time elapses, and when such evaporation gas is discharged into the atmosphere, not only waste of fuel, but also non-combustible gas is emitted, thereby causing pollution. Accordingly, the vehicle includes a canister purge system that supplies boil-off gas generated in the fuel tank to the intake side of the engine.

The canister purge system includes a canister that traps the vapor vapor generated in the fuel tank and a purge control valve that purges the vaporized gas trapped in the canister to the intake side of the engine. It can contain. The purge control valve is opened by a controller (engine control unit, engine control module, etc.) under the purge control conditions of the engine, that is, the engine negative pressure is sufficiently formed, and the evaporated gas collected in the canister is purged to the intake of the engine. Can be.

A naturally aspirated engine that draws air by the negative pressure naturally generated when the piston moves downward in the cylinder includes a single-pass canister purge system having one purge passage connecting the canister and the downstream side of the throttle valve.

For engine downsizing, a forced intake engine equipped with a turbocharger may frequently generate static pressure (higher pressure than atmospheric pressure) in the intake manifold when compressed air compressed by the operation of the turbocharger is sucked into the intake manifold. Thereby, purging of the canister does not work smoothly. Thus, the forced intake engine includes a dual path canister purge system configured to purge the boil-off gas from the canister downstream of the throttle valve and upstream of the compressor of the turbocharger.

The dual pass canister purge system includes a first purge passage connecting the downstream side of the purge control valve and the throttle valve, a second purge passage connecting the upstream side of the purge control valve and the compressor, and compressed air from the downstream side of the compressor. It includes a recirculation flow path to allow recirculation to the upstream side of the, and an ejector installed on the recirculation path. The ejector is configured to connect the recirculation passage, the second purge passage, and the upstream side of the compressor.

In the dual-pass canister purge system, when the pressure of the surge tank is negative, a vacuum purge mode in which the vaporized gas is purged from the surge tank to the downstream side of the throttle valve through the first purge passage is executed, and the turbocharger is operated. In the case where the pressure of the surge tank is constant pressure, a boost purge mode in which the vaporized gas is purged from the surge tank to the upstream side of the compressor through the second purge passage is performed.

On the other hand, the conventional single-pass canister purge system and dual-pass canister purge system do not fully utilize the pressure information of the intake system, such as atmospheric pressure, inlet pressure of the intake pipe, boost pressure, and surge tank pressure (or intake manifold pressure). There was a drawback that the opening and closing of the purge control valve could not be effectively controlled according to the operating conditions of the engine.

The items described in this background section are written to improve the understanding of the background of the invention, and may include matters other than the prior art already known to those of ordinary skill in the field to which this technology belongs.

The present invention was devised in consideration of the above points, and it is possible to accurately check the purge conditions according to the operating conditions of the engine by sufficiently utilizing the overall pressure information of the intake system using the pressure-based purge map, and Accordingly, the object of the present invention is to provide a control method of a canister purge system capable of precisely controlling a purge control valve.

Control method of the canister purge system according to the present invention for achieving the above object,

A single-pass canister purge system configured to purge evaporated gas only to the downstream side of the throttle valve and a dual-pass canister purge system configured to purge the evaporated gas to the downstream side of the throttle valve and the upstream side of the compressor. Is aware,

When the single-pass canister purge system is recognized, a single purge mode is executed using a pressure-based single purge map.

When the dual pass canister purge system is recognized, the dual purge mode is executed using the pressure-based dual purge map.

The single purge mode checks the current purge condition of the single pass canister purge system by the single purge map, and controls the purge control valve according to the confirmed current purge condition,

The dual purge mode may check the current purge condition of the dual pass canister purge system by the dual purge map, and control the purge control valve according to the confirmed current purge condition.

The single purge mode checks the current open / closed state of the purge control valve, receives the current operating condition of the engine and the current pressure condition of the intake pipe, and purges the current of the single pass canister purge system based on the single purge map. It is set to check the conditions and control the purge control valve according to the confirmed current purge conditions.

The single purge map has a negative pressure purge region, a transition region, and a single purge non-distinguishable region divided according to an operating condition of an engine and a pressure condition of an intake pipe. , The transition region may be a region where valve chattering can occur, and the single purge-incapable region may be a region in which evaporation gas cannot move to the downstream side of the throttle valve.

The single purge map is mapped by a combination of a first pressure map and a second pressure map, and the first pressure map is a map in which inlet pressure of an intake pipe is mapped according to engine load and engine speed, and the second pressure is mapped. The map may be a map in which the pressure of the surge tank according to the engine load and engine speed is mapped.

The dual purge mode checks the current open / closed state of the purge control valve, receives the current operating condition of the engine, and checks the current purge condition of the dual pass canister purge system based on the dual purge map, and confirms the It is set to control the purge control valve according to the current purge condition.

After receiving the current operating conditions of the engine, a surge margin rate corresponding to the current operating conditions of the engine is calculated based on the surge margin map, and the purge control valve can be closed when the surge margin rate satisfies the surge generation condition. have. The surge margin map may be a map displaying a surge margin rate according to driving conditions.

If the surge margin rate does not satisfy the surge generation condition, the current purge condition of the dual pass canister purge system may be checked based on the dual purge map, and the purge control valve may be controlled according to the confirmed current purge condition.

The dual purge map has a negative pressure purge region, a mixed purge region, a transition region, and a boost purge region divided according to the operating conditions of the engine and the pressure conditions of the intake pipe, and in the negative pressure purge region, only the downstream side of the throttle valve It is a moving area, and the mixed purge area is an area in which the evaporated gas is movable at a relatively high rate to the downstream side of the throttle valve and is movable at a relatively small rate to the upstream side of the compressor, and the transition area is valve chattering. A possible area, and the boost purge area may be an area in which the evaporated gas moves only upstream of the compressor.

The dual purge map is mapped by a combination of a first pressure map, a second pressure map, and a third pressure map, and the first pressure map is a map in which inlet pressure of an intake pipe is mapped according to engine load and engine speed. Wherein, the second pressure map may be a map in which the pressure of the surge tank according to the engine load and engine speed is mapped, and the third pressure map may be a map in which boost pressure is mapped according to the engine load and engine speed.

The dual purge map includes a surge generation area in which the surge of the compressor can be generated, and the surge generation area may be defined by a threshold line of a surge margin rate for determining whether a surge is generated in the compressor.

According to the present invention, by fully utilizing the overall pressure information of the intake system using the pressure-based purge map, it is possible to accurately check the purge conditions according to the operating conditions of the engine, and precisely control the purge control valve according to the confirmed purge conditions. There is an advantage.

1 is a view showing a single-pass canister purge system.
2 is a diagram showing a dual-pass canister purge system.
3 is a flowchart illustrating a control method of a canister purge system according to an embodiment of the present invention.
4 is a flowchart illustrating the single purge mode of FIG. 3.
5 is a view showing a pressure-based single purge map.
6 is a flowchart illustrating the dual purge mode of FIG. 3.
7 is a view showing a pressure-based dual purge map.
8 is a view showing a first pressure map showing the inlet pressure of the intake pipe according to the operating conditions of the engine.
9 is a view showing a second pressure map showing the pressure of the surge tank according to the operating conditions of the engine.
10 is a view showing a third pressure map showing the boost pressure according to the operating conditions of the engine.
11 is a view showing the performance curve of the compressor according to the operating conditions of the engine.
12 is a view showing a surge margin ratio map showing a surge margin ratio according to the operating conditions of the engine.
13 is a diagram showing a dual purge map displaying a threshold line of the surge margin rate according to the operating conditions of the engine.
14 is a diagram showing the performance curve of the compressor with four evaluation points displayed.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. It should be noted that in adding reference numerals to the components of each drawing, the same components have the same reference numerals as possible even though they are displayed on different drawings. In addition, in describing the embodiments of the present invention, when it is determined that detailed descriptions of related well-known configurations or functions interfere with the understanding of the embodiments of the present invention, detailed descriptions thereof will be omitted.

In describing the components of the embodiments of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, or order of the component is not limited by the term. In addition, unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

1 shows a single pass canister purge system 100 mounted on a naturally aspirated engine.

Referring to FIG. 1, the single-pass canister purge system 100 throttles the canister 110 for collecting the evaporation gas generated in the fuel tank 9 and the vapor vapor collected in the canister 110. And a purge control valve 130 that allows purging to the downstream side of the valve 17.

The engine 1 of FIG. 1 does not rely on forced suction through a turbocharger or a supercharger, etc., and relies solely on atmospheric pressure, and naturally aspirated engine that inhales air by negative pressure generated naturally when the piston moves downward in the cylinder. to be. The intake system 3 of the engine 1 may include an intake manifold 2 and an intake air duct 5, and the intake manifold 2 is an engine from the surge tank 4 and the surge tank 4 ( 1) may have a plurality of runners extending to each cylinder side, and an air cleaner 6 and a throttle valve 7 may be mounted on the intake pipe 5.

The air cleaner 6 may be arranged on the inlet side of the intake pipe 5, and the throttle valve 7 may be arranged on the downstream side of the air cleaner 6. The throttle valve 7 may be an electronic throttle control (ETC) electrically connected to an accelerator pedal.

The fuel tank 9 is configured to store fuel, and the fuel stored in the fuel tank 9 can be supplied to a fuel injector (not shown) through a fuel system (not shown). As the fuel is vaporized in the fuel tank 9, a vapor vapor is generated. The canister 110 may be connected to the fuel tank 9 through the conduit 115, and the boil-off gas generated in the fuel tank 9 may be transmitted to the canister 110 through the conduit 115, and the boil-off gas Can be trapped in the canister 110. According to an example, the canister 110 may have activated-carbon.

The canister 110 may have a canister close valve (120) that selectively opens and closes the vent port 111 communicating with the outside. For example, the canister closed valve 120 may be configured to open during normal operation and close upon leakage diagnosis.

The purge control valve 130 may be disposed between the canister 110 and the intake system 3. By opening the purge control valve 130, the vapor vapor collected in the canister 110 can be moved to the intake pipe 5. According to an embodiment, the purge control valve 130 may be configured as a solenoid valve, and thus the purge control valve 130 may be driven along a duty cycle set by the controller 50.

The canister 110 and the intake pipe 5 may communicate by the purge passage 140, and the purge control valve 130 may be installed in the purge passage 140. The purge passage 140 connects the canister 110 and the downstream side of the throttle valve 7, whereby evaporation gas flows downstream from the canister 110 through the purge passage 140 through the throttle valve 7 Can move to the side. As described above, the single-pass canister purge system 100 of FIG. 1 may purge the boil-off gas collected in the canister 110 to the downstream side of the throttle valve 7 through one purge passage 140.

Check valve 150 is installed in the purge passage 140, the check valve 150 allows the evaporation gas to flow from the purge control valve 130 to the downstream side of the throttle valve (7), evaporation gas or intake, etc. The purge control valve 130 may be configured to prevent backflow. That is, the check valve 150 is a one-way valve that allows only one-way flow in which the evaporated gas flows only to the downstream side of the throttle valve 7.

The first pressure sensor 31 may be configured to measure the inlet-side pressure of the intake pipe 5. According to the embodiment of FIG. 1, the first pressure sensor 31 may be disposed adjacent to the air cleaner 6 on the intake pipe 5.

The second pressure sensor 32 may be configured to measure the pressure of the surge tank 4 of the engine 1. According to the embodiment of FIG. 1, the second pressure sensor 32 may be disposed at a portion adjacent to the surge tank 4 of the engine 1 on the downstream side of the throttle valve 3.

2 is a view showing a dual-pass canister purge system 200 mounted on a forced induction engine.

Referring to FIG. 2, the dual-pass canister purge system 200 throttles the canister 210 for collecting the evaporation gas generated in the fuel tank 5 and the vapor vapor collected in the canister 210. And a purge control valve 230 that allows purging to the downstream side of the valve 17 and the upstream side of the compressor 21.

The engine 10 of FIG. 2 is a forced intake engine adopting an oxygen inhalation method that relies on forced inhalation through the turbocharger 20. The intake machine 13 of the engine 10 may include an intake manifold 12 and an intake air pipe 15, and the intake manifold 12 may have a surge tank 14.

The compressor 21 of the turbocharger 20 may be mounted to the intake pipe 15. The turbocharger 20 may include a compressor (not shown) mounted on the exhaust pipe (not shown) of the compressor 21 and the engine 10 mounted on the intake pipe 15. The compressor 21 may be connected to a turbine (not shown) through a common shaft (not shown).

An air cleaner 16, a throttle valve 17, and an intercooler 25 may be provided in the intake air pipe 15. The air cleaner 16 may be disposed on the inlet side of the intake pipe 15, the intercooler 25 may be disposed on the downstream side of the compressor 21, and the throttle valve 17 is downstream of the intercooler 25. Can be placed on the side. The throttle valve 17 may be an electronic throttle control (ETC) that is electrically connected to an accelerator pedal.

The fuel tank 19 is configured to store fuel, and fuel vapor is generated in the fuel tank 19 as fuel is vaporized. The canister 210 may be connected to the fuel tank 19 through the conduit 215, and the boil-off gas generated in the fuel tank 19 may be delivered to the canister 210 through the conduit 215, and the boil-off gas Can be trapped in the canister 210. According to an example, the canister 210 may have activated-carbon.

The canister 210 may have a canister closed valve 220 that selectively opens and closes the vent port 211 communicating with the outside. For example, the canister closed valve 220 may be configured to open during normal operation and close upon leakage diagnosis.

The purge control valve 230 may be disposed between the canister 210 and the intake system 13. By opening the purge control valve 230, the vapor vapor collected in the canister 210 may move to the intake air pipe 15. According to an embodiment, the purge control valve 230 may be configured as a solenoid valve, and thus the purge control valve 230 may be driven along a duty cycle set by the controller 50.

The canister 210 and the intake pipe 15 may communicate with each other by the purge passage 240, and the purge control valve 230 may be installed in the purge passage 240.

The purge passage 240 may be configured to connect the canister 110 with the downstream side of the throttle valve 7 and the canister 110 with the upstream side of the compressor 23.

According to one embodiment, the purge passage 240 is branched from the downstream of the purge control valve 230 to the first purge passage 241 and the second purge passage 242 (The purge passage 240 divides into a first passage 241) and a second passage 242 at a position downstream of the purge control valve 230). The purge passage 240, the first purge passage 241, and the second purge passage 242 may be connected by a tee connector (245).

The first purge passage 241 is configured to connect the purge control valve 230 and the downstream side of the throttle valve 17. The first check valve 251 is installed in the first purge passage 241, and the first check valve 251 allows the evaporation gas to flow from the purge control valve 230 to the downstream side of the throttle valve 17, It may be configured to prevent boil-off gas or intake air from flowing back to the purge control valve 230. That is, the first check valve 251 is a one-way valve that allows only one-way flow in which the evaporated gas flows only to the downstream side of the throttle valve 17.

The second purge passage 242 is configured to connect the purge control valve 230 and the upstream side of the compressor 21. The second check valve 252 is installed in the second purge passage 242, the second check valve 252 allows the evaporation gas to flow from the purge control valve 230 to the upstream side of the compressor 21, evaporation Gas or outside air may be configured to prevent backflow into the purge control valve 230. That is, the second check valve 252 is a one-way valve that allows only one-way flow in which the evaporated gas flows only upstream of the compressor 21.

The dual-pass canister purge system 200 further includes a recirculation passage 260 and an ejector 270 for generating negative pressure at the downstream side of the second purge passage 242, and the recirculation flow path 260 is It may be configured to recycle compressed air from the downstream side of the compressor 21 to the upstream side of the compressor 21. According to one example, the recirculation passage 260 is the upstream side of the compressor 21 (the portion adjacent to the inlet of the compressor 21) and the upstream side of the throttle valve 17 (the portion adjacent to the inlet of the throttle valve 17) It can be configured to connect. The ejector 270, which is a forced negative pressure device that generates negative pressure, may be disposed in the recirculation passage 260, and the ejector 270 is upstream of the recirculation passage 260, the second purge passage 242, and the compressor 21. It can be configured to connect the sides. Accordingly, the evaporated gas that has passed through the second purge passage 242 may be moved to the upstream side of the compressor 21 by the ejector 270.

A mixer 23 may be disposed upstream of the compressor 21, and an EGR conduit 24 may be connected between the mixer 23 and the inlet of the compressor 21. Accordingly, the mixer 23 may mix ambient air, recirculated compressed air, and EGR gas.

The first pressure sensor 31 may be configured to measure the inlet side pressure of the intake pipe 15. According to the embodiment of FIG. 2, the first pressure sensor 15 may be disposed on the upstream side of the compressor 21. In particular, the first pressure sensor 31 may be disposed between the inlet of the mixer 23 and the compressor 21.

The second pressure sensor 32 may be configured to measure the pressure of the surge tank 14. In particular, the second pressure sensor 32 may be disposed at a portion adjacent to the surge tank 14 on the downstream side of the throttle valve 17.

The third pressure sensor 33 may be configured to measure the pressure on the downstream side of the compressor 21, that is, the "boost pressure". The third pressure sensor 33 may be disposed on the downstream side of the compressor 21. In particular, the third pressure sensor 33 may be disposed between the intercooler 25 and the throttle valve 17.

The present invention may include a controller 50 selectively connected to the single pass canister purge system 100 of FIG. 1 and the dual pass canister purge system 200 of FIG. 2.

The controller 50 may be configured to receive information from the pressure sensors 31, 32, 33 and various other sensors and to transmit control signals to the actuators. The controller 50 may include a processor 51 and a memory 52, and the processor 51 receives control instructions and data stored in the memory 52 and issues control instructions to the actuators. Can transmit. The actuators may be fuel injectors (not shown), throttle valves 7 and 17, EGR valves (not shown), purge control valves 130 and 230, and the like. The memory 52 may include read only memory (ROM), random access memory (RAM), electrically programmable read only memory (EPROM), high speed clokc, and the like. The controller 50 may be stand-alone or may be embedded in a vehicle controller such as an engine control unit or an engine control module. (controller 50 may be a stand alone device or may be embedded in one or more of the vehicle controller such as Engine Control Unit, Engine Control Module.)

The memory 52 stores the unified software, and the unified software may include a single purge mode conforming to the single pass canister purge system 100 and a dual purge mode conforming to the dual pass canister purge system 200.

The controller 50 may be configured to recognize any one of the single pass canister purge system 100 and the dual pass canister purge system 200 by the set flag bit. For example, if the controller 50 does not recognize the third sensor 33 measuring the boost pressure (ie, the third sensor 33 is not connected to the controller 50), the flag bit is set to “0”. , When the controller 50 recognizes the third sensor 33 that measures the boost pressure (that is, when the third sensor 33 is connected to the controller 50), the flag bit may be set to “1”. Accordingly, the controller 50 may recognize the single-pass canister purge system 100 or the dual-pass canister purge system 200 by the set flag bit, through which the controller 50 can perform the single-pass canister purge system 100 When recognizing, the controller 50 loads and executes a single purge mode conforming to the single pass canister purge system 100, and when the controller 50 recognizes the dual pass canister purge system 200, the controller 50 performs dual It can be programmed to load and execute a dual purge mode consistent with the pass canister purge system 200.

Referring to FIG. 3, the controller 50 recognizes whether the single-pass canister purge system 100 is installed in the vehicle through the flag bit set as described above (S1).

When it is recognized that the single-pass canister purge system 100 is installed, the controller 50 executes the single purge mode S300 of FIG. 4 using the pressure-based single purge map 60 (S2).

When it is recognized that the dual pass canister purge system 200 is installed, the controller 50 executes the dual purge mode S400 of FIG. 6 using the pressure-based dual purge map 70 (S3).

4, when the controller 50 starts the single purge mode (S300), the single pass canister purge system 100 checks the current open / closed state of the purge control valve 130 (S301). Through the output current or output voltage of the purge control valve 130, it is possible to check whether the purge control valve 130 is opened or closed.

The controller 50 monitors the current operating conditions of the engine by receiving information related to engine load, such as engine torque measured by a torque sensor, information related to engine speed measured by a speed sensor, etc. (S302).

The controller 50 receives air by receiving the inlet side pressure of the intake air pipe 5 measured by the first pressure sensor 31 and the pressure of the surge tank 4 measured by the second pressure sensor 32 and the like. The current pressure condition of the conduit 5 is monitored (S303).

The processor 51 of the controller 50 loads the pressure-based single purge map 60 stored in the memory 52, and the processor 51 of the controller 50 receives the engine load and engine speed received in step S302, The current purge condition of the single-pass canister purge system 100 is confirmed by substituting the pressure of the inlet side of the intake pipe 5 and the pressure of the surge tank 4 into the loaded single purge map 60 received in step S303. (S304). That is, the controller 50 has the current purge condition of the single-pass canister purge system 100 according to the engine load and engine speed, the inlet pressure of the intake pipe 5 and the pressure of the surge tank 4, etc. It can be confirmed which region (61, 62, 63) of). Meanwhile, the single purge map 60 may be mapped based on the overall pressure information of the intake system, such as the pressure of the surge tank 4 and the inlet pressure of the intake pipe 5, as described later.

5 is a diagram illustrating a pressure-based single purge map 60 according to an embodiment. Referring to FIG. 5, the single purge map 60 may have a plurality of regions 61, 62, and 63 divided according to operation conditions of the engine, such as engine load and engine speed. The plurality of regions 61, 62, and 63 may be divided into a negative pressure purge region 61, a transition region 62, and a single purge-incapable region 63. In Fig. 5, the engine load is illustrated as the brake mean effective pressure (BMEP) of the engine.

In the single purge map 60 of FIG. 5, the negative pressure purge area 61 is a low load condition in which the engine has a relatively low effective braking average pressure (engine load), and the pressure in the surge tank 4 is negative pressure (below atmospheric pressure). Is a condition. In the negative pressure purge region 61, the evaporated gas may travel to the downstream side of the throttle valve 7 through the check valve 150. The negative pressure purge region 61 may be a region where the purge efficiency of the single-pass canister purge system 100 is highest because the pressure of the surge tank 4 is negative. If the current operating condition of the engine, such as the current engine load and the current engine speed, satisfies the negative pressure purge region 61, the controller 50 can confirm that the current purge condition of the single-pass canister purge system 100 is a negative pressure purge condition, The controller 50 may control the purge control valve 130 according to a relatively high first duty cycle. In particular, in the negative pressure purge region 61, since the pressure of the surge tank 4 is negative, the one-way flow by the check valve 150 can be very advantageous when the purge control valve 130 is opened.

In the single fuzzy map 60 of FIG. 5, the transition region 62 is a medium load condition in which the engine's braking average effective pressure (engine load) is relatively medium, and the pressure in the surge tank 4 becomes similar to atmospheric pressure. Condition. As described above, since the transition region 62 is a condition in which the pressure of the surge tank 4 is similar to atmospheric pressure, a region in which valve chattering is likely to occur due to a pressure difference when the check valve 150 is opened and closed is high. Due to this, when the evaporation gas passes through the check valve 150 and moves to the downstream side of the throttle valve 7 by the opening of the purge control valve 130, it may be affected by the valve chattering of the check valve 150. have. Accordingly, since the reliability of the purge operation of the evaporated gas in the transition region 62 may be extremely reduced, it is necessary to very carefully control the operation of the purge control valve 130 in consideration of the effect of valve chattering. If the current operating condition of the engine, such as the current engine load and the current engine speed, satisfies the transition region 62, the controller 50 may confirm that the current purge condition of the single-pass canister purge system 100 is a transition condition. In particular, it may not be efficient to control the operation of the purge control valve 130 in the transition region 62 on the purge efficiency side of the boil-off gas, so the operation of the purge control valve 130 in the transition region 62 is not inevitable. It will be desirable to keep the purge control valve 130 closed by stopping.

 In the single purge map 60 of FIG. 5, the single purge non-existing region 63 is a high load condition in which the engine has an average effective braking pressure (engine load) and a pressure in the surge tank 4 is higher than atmospheric pressure. . In the single purge impossible area 63, the evaporated gas does not move to the downstream side of the throttle valve 7 through the check valve 150. If the current operating condition of the engine, such as the current engine load and the current engine speed, satisfies the single purge impermissible area 63, the controller 50 can confirm that the current purge condition of the single-pass canister purge system 100 is a single purge imperative. Thereby, the controller 50 may control the purge control valve 130 to maintain the closed state of the purge control valve 130.

The controller 50 controls the purge control valve 130 according to which region (61, 62, 63) of the single purge map 60, that is, which purge condition is satisfied by the current purge condition of the single pass canister purge system 100. ) Is opened or closed and the opening degree is controlled (S305). For example, if the current purge condition of the single-pass canister purge system 100 corresponds to the negative pressure purge region 61 of the single purge map 60, the controller 50 increases the purge control valve 130 to a relatively high first duty cycle. By controlling accordingly, the opening rate of the purge control valve 130 can be adjusted relatively large. If the current purge condition of the single pass canister purge system 100 corresponds to the transition region 62 of the single purge map 60, the controller 50 considers the effect of valve chattering when purging of the evaporation gas is inevitable. The purge control valve 130 is carefully controlled and the purge control valve 130 is kept closed by stopping the opening operation of the purge control valve 130 unless purging of the evaporation gas is inevitable. When the current purge condition of the single-pass canister purge system 100 corresponds to the single purge non-purge area 63 of the single purge map 60, the controller 50 purges by controlling to stop the opening operation of the purge control valve 130. The control valve 130 can be kept closed.

Referring to FIG. 6, when the controller 50 starts the dual purge mode (S400), the dual pass canister purge system 200 checks the current open / closed state of the purge control valve 230 (S401). Through the output current or output voltage of the purge control valve 230, it is possible to check whether the purge control valve 230 is opened or closed or the opening degree of the purge control valve 230.

The controller 50 monitors the current operating conditions of the engine by receiving information related to engine load, such as engine torque measured by a torque sensor, etc., and information related to engine speed, such as engine speed measured by a speed sensor, etc. ( S402).

The controller 50 includes the inlet pressure of the intake pipe 15 measured by the first pressure sensor 31, the pressure of the surge tank 14 measured by the second pressure sensor 32, and the third pressure sensor ( 33) The current pressure condition of the intake system is monitored by receiving the boost pressure or the like measured in step S403.

The processor 51 of the controller 50 dual purge the engine load and engine speed received in step S402, the inlet pressure of the intake pipe 15 received in step S403, the pressure of the surge tank 14, and the boost pressure. The current purge condition of the dual-pass canister purge system 200 is confirmed by substituting it into the map 70 (S404). That is, the controller 50 has dual purge according to the current purge condition of the dual-pass canister purge system 200 according to the engine load and engine speed, the inlet pressure of the intake pipe 15, the pressure of the surge tank 14, and the boost pressure. It can be confirmed which region 71, 72, 73, 74 of the map 70 corresponds. Meanwhile, the dual purge map 70 may be mapped based on the overall pressure information of the intake system, such as the pressure of the surge tank 14, the inlet pressure of the intake pipe 15, and the boost pressure.

7 is a diagram illustrating a pressure-based dual purge map 70 according to an embodiment. Referring to FIG. 7, the dual purge map 70 may have a plurality of regions 71, 72, 73 and 74 divided according to engine load and engine speed. The plurality of regions 71, 72, 73, and 74 may be divided into a negative pressure purge region 71, a mixed purge region 72, a transition region 73, and a boost purge region 74. In FIG. 7, the engine load is illustrated as the brake mean effective pressure (BMEP) of the engine.

In the dual purge map 70 of FIG. 7, the negative pressure purge region 71 is a low load condition in which the engine's braking average effective pressure (engine load) is relatively low, a low speed condition in which the engine speed is low, and a surge tank 14 ) Is a condition where the pressure is a negative pressure (atmospheric pressure or less) and the boost pressure is a first set pressure or less. The first set pressure is a threshold for forming a forced negative pressure by the ejector 270, and when the boost pressure is equal to or less than the first set pressure, the negative pressure by the ejector 270 cannot be formed. In the negative pressure purge region 71, since the pressure of the surge tank 4 is negative pressure, the evaporated gas can move to the downstream side of the throttle valve 17 through the first purge passage 241, and the boost pressure is equal to or less than the first set pressure. The evaporated gas does not move upstream of the compressor 21 through the second purge passage 242. If the current operating condition of the engine, such as the current engine load and the current engine speed, satisfies the negative pressure purge region 71, the controller 50 can confirm that the current purge condition of the dual-pass canister purge system 200 corresponds to the negative pressure purge condition. have.

In the dual purge map 70 of FIG. 7, in the mixed purge region 72, the braking average effective pressure (engine load) of the engine is a relatively high heavy load condition compared to the negative pressure purge region 71, and the surge tank 14 The condition is that the pressure of is a negative pressure (atmospheric pressure or less), and the boost pressure is at least a first preset pressure or less than a second preset pressure. The first set pressure is a threshold for forming a forced negative pressure by the ejector 270, and the second set pressure is a threshold for forming the forced negative pressure by the ejector 270 very stably, and the second set pressure is It is higher than the first set pressure. In the mixed purge region 72, since the boost pressure is greater than or equal to the first set pressure and less than or equal to the second set pressure, negative pressure by the ejector 270 may be formed, but formation of the negative pressure is not stable, and thus the operating efficiency of the ejector 270 Since this is relatively low, the purge efficiency of the evaporated gas through the second purge passage 242 may be relatively low. In addition, in the mixed purge region 72, since the pressure of the surge tank 14 is negative, the evaporated gas can move at a higher rate to the downstream side of the throttle valve 17 through the first purge passage 241. That is, in the mixed purge region 72, the evaporated gas may move at a relatively high rate by the first purge passage 241, and may move at a relatively low rate through the second purge passage 242. In this way, since the boost pressure in the mixed purge region 72 is relatively low, especially when the atmospheric pressure is low, the possibility of surge generation of the compressor 21 may be increased, so that the controller 50 has the first purge passage 241. It is preferable to control the opening degree of the purge control valve 230 to move to the side. If the current operating conditions of the engine, such as the current engine load and the current engine speed, satisfy the mixed purge region 72, the controller 50 can confirm that the current purge condition of the dual-pass canister purge system 200 corresponds to the mixed purge condition. The controller 50 may control the opening degree of the purge control valve 230 so that the evaporated gas moves toward the first purge passage 241 side.

In the dual purge map 70 of FIG. 7, the transition region 73 is a heavy load condition in which the engine's braking average effective pressure (engine load) is higher than that of the mixed purge region 73, and the pressure of the surge tank 14 is atmospheric pressure. It is similar to and is a condition in which the boost pressure is greater than or equal to the first set pressure and less than or equal to the second set pressure. In the transition region 73, since the boost pressure is greater than or equal to the first set pressure and less than or equal to the second set pressure, negative pressure by the ejector 270 may be formed, but formation of the negative pressure is not stable, and thus the operating efficiency of the ejector 270 Since it is relatively low, the purge efficiency of the evaporated gas through the second purge passage 242 may be relatively low. Also, in the transition region 73, since the pressure of the surge tank 14 is similar to atmospheric pressure, a region in which valve chattering is likely to occur due to a pressure difference when the first check valve 251 is opened and closed is high. Due to this, when the evaporation gas passes through the first check valve 251 by the opening of the purge control valve 240 and moves to the downstream side of the throttle valve 17, by the valve chattering of the first check valve 251 Can be affected. Accordingly, since the reliability of the purge operation of the evaporated gas in the transition region 73 may be extremely reduced, it is necessary to very carefully control the operation of the purge control valve 230 in consideration of the effect of valve chattering. If the current operating condition of the engine, such as the current engine load and the current engine speed, satisfies the transition region 73, the controller 50 may confirm that the current purge condition of the dual pass canister purge system 200 corresponds to the transition condition. In particular, it may not be efficient to control the operation of the purge control valve 230 in the transition region 73 on the purge efficiency side of the boil-off gas, so the operation of the purge control valve 230 in the transition region 73 is not inevitable. It will be desirable to keep the purge control valve 230 closed by stopping.

In the dual purge map 70 of FIG. 7, the boost purge region 74 is a high load condition in which the engine has a high brake average effective pressure (engine load), a pressure in the surge tank 14 becomes greater than atmospheric pressure, and a boost pressure. It is a condition above the second set pressure. In the boost purge region 74, since the boost pressure is greater than or equal to the second set pressure, a forced negative pressure by the ejector 270 may be stably formed, and the operation efficiency of the ejector 270 may be relatively highest, and evaporation gas May move upstream of the compressor 21 through the second purge passage 242. That is, the boost purge region 74 may be the region having the highest purge efficiency by the second purge passage 252 since the operation efficiency of the ejector 270 is high. Further, in the boost purge region 74, the pressure of the surge tank 14 becomes higher than atmospheric pressure, and thus the evaporated gas cannot move to the downstream side of the throttle valve 17. If the current operating condition of the engine, such as the current engine load and the current engine speed, satisfies the boost purge region 74, the controller 50 can confirm that the current purge condition of the dual pass canister purge system 200 corresponds to the boost purge condition. have.

The controller 50 purge control valve according to which region (71, 72, 73, 74) of the dual purge map 70 satisfies the current purge condition of the dual pass canister purge system 200, that is, the purge condition It controls whether the opening and closing of the 230 and the opening degree, etc. (S405). For example, if the current purge condition of the dual pass canister purge system 200 corresponds to the negative pressure purge region 71 of the dual purge map 70, the controller 50 sets the purge control valve 230 to a relatively high first duty cycle. Accordingly, the opening rate of the purge control valve 230 can be relatively controlled by controlling. If the current purge condition of the dual-pass canister purge system 200 corresponds to the mixed purge area 72 of the dual purge map 70, the controller 50 purge control valve to move the evaporated gas toward the first purge passage 241 The opening degree of 230 can be controlled. If the current purge state of the dual pass canister purge system 200 corresponds to the transition area 73 of the dual purge map 70, purging of the evaporation gas is inevitable, and the purge control valve is carefully considered in consideration of the effect of valve chattering. The purge control valve 230 is maintained in a closed state by controlling the opening operation of the 230 and stopping the opening operation of the purge control valve 230 unless purging of the evaporation gas is inevitable. If the current purge condition of the dual-pass canister purge system 200 corresponds to the boost purge area 74 of the dual purge map 70, the controller 50 purges by controlling the purge control valve 230 along the first duty cycle. The opening degree of the control valve 230 can be adjusted relatively large.

8 is a first pressure map in which inlet pressures of the intake pipes 5 and 15 are mapped according to operating conditions of the engine, such as engine speed and engine load. As shown in Fig. 8, the inlet pressures of the intake pipes 5 and 15 show almost the same pressure distribution over the entire operating conditions of the engine. That is, the pressure at the inlet side of the intake pipes 5 and 15 may be kept constant regardless of the engine speed and the engine load in a state in which atmospheric conditions such as altitude according to the movement of the vehicle remain unchanged. In Fig. 8, the engine load is illustrated as the brake mean effective pressure (BMEP) of the engine.

9 is a second pressure map showing the pressure of the surge tanks 4 and 14 according to the operating conditions of the engine, such as engine speed and engine load. As shown in FIG. 9, as the braking average effective pressure of the engine increases, the pressure of the surge tanks 4 and 14 may increase. That is, it can be seen that as the load of the engine increases, the pressure of the surge tanks 4 and 14 increases. In Fig. 9, the engine load is illustrated as the brake mean effective pressure (BMEP) of the engine.

10 is a third pressure map showing a boost pressure (average pressure on the downstream side of the compressor 21) according to the operating conditions of the engine, such as engine speed and engine load. As shown in FIG. 10, the boost pressure may increase as the engine brake average effective pressure increases. That is, it can be seen that as the engine load increases, the boost pressure increases. In Fig. 10, the engine load is illustrated as the brake mean effective pressure (BMEP) of the engine.

According to an embodiment, by combining the first pressure map of FIG. 8 and the second pressure map of FIG. 9, the single purge map 60 of FIG. 5 may be mapped, and various correction values when mapping the single purge map 60 May be applied. The average brake effective pressure of the engine can be calculated by substituting the engine torque into the average brake effective pressure formula.

According to an embodiment, the dual purge map 70 of FIG. 7 may be mapped by combining the first pressure map of FIG. 8, the second pressure map of FIG. 9, and the third pressure map of FIG. 10, and the dual purge map ( In the mapping of 70), various correction values may be applied. The average brake effective pressure of the engine can be calculated by substituting the engine torque into the average brake effective pressure formula.

On the other hand, when checking the current purge condition of the single purge mode (S300) and the current purge condition of the dual purge mode (S400), the inlet pressure of the intake pipes (5, 15), the pressure of the surge tanks (4, 14), boost By substituting pressure, etc. into the first pressure map, the second pressure map, and the third pressure map, it is possible to more accurately check the local purge conditions.

On the other hand, since the dual-pass canister purge system 200 has a compressor 21 of the turbocharger 20, the evaporated gas purged by the ejector 270 due to the surge of the compressor 21 is an air cleaner 16 ). Surge of the compressor 21 occurs when the pressure ratio to flow rate is high, and the rotating body of the compressor 21 is idle, meaning an unstable state in which the flow of the flow is irregular. In particular, when the vehicle is operating in the highlands, the atmospheric pressure may be lowered, and thus the flow rate of the outside air flowing into the compressor 21 may be relatively low, while the compression ratio of the compressor 21 may be increased, so the surge of the compressor 21 is increased. ) May increase.

11 is a surge region (S) and a non-surge region (S) divided by a surge line (SL, Surge Line) and a surge line (SL) according to the flow rate (mass flow rate) and pressure ratio (pressure ratio) of the compressor 21 ( NS) is a performance curve of the compressor 21.

As illustrated in FIG. 11, the surge margine rate (SgX) may be defined as being close to the surge line SL according to the rotational speed of the compressor 21 (1200 rpm, 1600 rpm, 3000 rpm, etc.). . In FIG. 11, the surge margin rate SgX is the intersection of the flow rate Xf of point A, which is a point in the non-surge area NS, and the intersection I of the surge line SL that meets the virtual line extending in the horizontal direction from point A. It is defined as the difference value (SgX = Xf-Xs) between the flow rates (Xs). In addition, the surge margin ratio SgX may be determined according to the flow rate of the compressor 21 and the rotational speed of the compressor 21 in the non-surge area NS of the compressor 21. It can be seen from FIG. 11 that the smaller the surge margin rate SgX, the higher the possibility that the fluid flows back from the inlet of the compressor 21 to the air cleaner 16. For example, when the vehicle is operating at high altitude, the atmospheric pressure is lowered, the supercharging effect is reduced (the flow rate of the compressor 21 is decreased), and the pressure ratio of the compressor 21 may be increased, so the surge margin ratio SgX may be small. Meanwhile, as illustrated in FIG. 11, the minimum value of the Inlet Guide Vane (IGV) and the maximum value of the Inlet Guide Vane (IGV) may be variously set.

12 is a surge margin ratio map showing a surge margin ratio SgX according to operating conditions such as engine speed and engine load equivalent. Referring to FIG. 12, as the engine speed and the engine load increase (see arrow K direction), the surge margin ratio SgX increases.

FIG. 13 shows a dual purge map 60 in which the surge margin rate SgX is displayed. 13, four evaluation points (A, B, C, and D) with a surge margin ratio of 11% or less are shown. FIG. 14 shows the performance curve of the compressor 21 in which four evaluation points (A, B, C, D) shown in FIG. 13 are displayed, and the four evaluation points (A, B, C, D) are the surge lines (SL). ). For example, when the vehicle is operating at high altitude, point A can move along the A 'direction, so it is very likely to meet the surge line SL. That is, the surge of the compressor 21 may occur, which increases the possibility that the evaporated gas purged by the ejector 270 flows back to the air cleaner 16.

According to an embodiment of the present invention, the surge margin ratio SgX of FIGS. 11 to 14 may be applied to the dual purge map 70 of FIG. 7. The dual purge map 70 of FIG. 7 may include a surge generation region 75 in which the surge of the compressor 21 is generated. The surge generation region 75 may be defined by a threshold line 76 of the surge margin rate SgX for determining whether the compressor 21 has surge generated. The threshold line 76 of the surge margin rate SgX may be variously changed according to engine conditions, altitude of a region in which the vehicle is operated, and the like.

According to one embodiment, as shown in FIG. 7, the surge generating region 75 is the rest of the region except the negative pressure purge region 71 in which the evaporation gas is not purged by the ejector 270, that is, the boost purge region 74 ), The transition region 73, and the mixed purge region 72. In particular, the surge generating region 75 can be biased to the engine's low speed conditions.

When the vehicle is operating in the highlands or when the boost pressure is reduced, the atmospheric pressure may be lowered, and the flow rate of the outside air flowing into the compressor 21 may be reduced. Accordingly, since the compression ratio compared to the flow rate of the compressor 21 may be increased, the possibility of surge of the compressor 21 may increase. For example, as the atmospheric pressure decreases in the mixed purge region 72, the transition region 73, and the boost purge region 74 of the dual purge map 70 or the compression ratio to the flow rate of the compressor 21 increases, the compressor 21 The likelihood of surge generation may increase, and thus, the evaporated gas purged by the ejector 270 may flow back to the air cleaner 16. The negative pressure purge region 71 of the dual purge map 70 does not need to consider the possibility of surge generation of the compressor 21 because the evaporation gas does not move upstream of the compressor 21 by the ejector 270, and thus surge generation occurs. The region 75 does not overlap the negative pressure purge region 71 of the dual purge map 70.

As described above, the present invention closes the purge control valve 230 in a condition where surge generation is possible using the dual purge map 70 in which the surge generation region 75 is set, and thus the evaporation gas is generated due to the surge of the compressor 21. It can effectively prevent leakage to the outside of the.

As described above, considering the possibility of surge generation of the compressor 21 due to a decrease in atmospheric pressure or a higher compression ratio compared to the flow rate of the compressor 21, each area of the dual purge map 70 is as follows. The negative pressure purge region 71 does not need to take into account the possibility of surge generation of the compressor 21 since the negative pressure by the ejector 270 is not formed. In the boost purge region 74, the negative pressure by the ejector 270 is smoothly formed, but there is a possibility that the surge of the compressor 21 is generated when the atmospheric pressure decreases or the boost pressure decreases. When the atmospheric pressure is low or the boost pressure decreases, the transition region 73 and the mixed purge region 72 may have a higher probability of surge generation of the compressor 21 than the boost purge region 74.

Referring to FIG. 6, after the step S402, the dual purge map 70 is loaded (S410), and the surge margin ratio SgX according to the current operating conditions of the engine is calculated based on the surge margin ratio map of FIG. 12. Then, based on the loaded dual purge map 70, it is determined whether the surge margin ratio SgX according to the current operating condition of the engine satisfies the surge generation condition (S411). Specifically, if the surge margin ratio SgX according to the engine speed and the engine load is within the surge generation area 75 of the dual purge map 70 of FIG. 7, the current operating condition of the engine satisfies the surge generation condition, If the surge margin ratio SgX according to the engine speed and the engine load is outside the surge generation area 75 of the dual purge map 70 of FIG. 7, the current operating condition of the engine does not satisfy the surge generation condition.

If the current surge margin ratio SgX according to the current operating condition of the engine does not satisfy the surge generation condition, steps S403, S404, and S405 may be sequentially performed. That is, if the surge margin ratio (SgX) according to the engine speed and the engine load is outside the surge generation area 75 of the dual purge map 70, the current purge condition of the dual pass canister purge system 200 is checked to confirm the purge control valve 230 ) Can be opened or closed and the opening rate can be controlled.

When the surge margin ratio SgX according to the current state of the engine satisfies the surge generation condition, the pressure upstream of the compressor 21 measured by the first pressure sensor 31 and the first and third pressure sensors 31, 33 Compression ratio of the compressor 21 calculated by can be confirmed (S412). By substituting the upstream pressure and compression ratio of the compressor 21 into the performance map of the compressor 21, it is possible to cross-verify that the upstream pressure and compression ratio of the compressor 21 is a surge generation condition, and the compressor 21 The performance map of can be stored in the memory 52 of the controller 50. And, if the surge margin rate (SgX) is within the surge generation area 75 of the dual purge map 70 of FIG. 7, the purge control valve may be used because the evaporated gas purged by the ejector 270 may flow back to the air cleaner 16 side. (230) is closed (S413).

According to the present invention as described above, by fully utilizing the overall pressure information of the intake system using the pressure-based purge map, it is possible to accurately check the purge conditions according to the operating conditions of the engine, and to accurately control the purge control valve according to the confirmed purge conditions. Can be controlled.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the claims below, and all technical spirits within the equivalent range should be interpreted as being included in the scope of the present invention.

1, 10: engine 2, 12: intake manifold
4, 14: surge tank 5, 15: intake air pipe
6, 16: Air cleaner 7, 17: Throttle valve
9, 19: fuel tank 31: first pressure sensor
32: second pressure sensor 33: third pressure sensor
100: single pass canister purge system
110: canister 130: purge control valve
140: purge passage 150: check valve
200: dual pass canister purge system
210: canister 230: purge control valve
240: purge passage 241: first purge passage
242: 2nd purge passage 251: 1st check valve
252: second check valve 260: recirculation passage
270: ejector

Claims (10)

A single-pass canister purge system configured to purge evaporated gas only to the downstream side of the throttle valve and a dual-pass canister purge system configured to purge the evaporated gas to the downstream side of the throttle valve and the upstream side of the compressor. Is aware,
When the single-pass canister purge system is recognized, a single purge mode is executed using a pressure-based single purge map.
When the dual pass canister purge system is recognized, the dual purge mode is executed using the pressure-based dual purge map.
The single purge mode checks the current purge condition of the single pass canister purge system by the single purge map, and controls the purge control valve according to the confirmed current purge condition,
The dual purge mode is a control method of a canister purge system that checks a current purge condition of the dual pass canister purge system by the dual purge map and controls a purge control valve according to the confirmed current purge condition. The method according to claim 1,
The single purge mode,
Check the current opening and closing state of the purge control valve,
Receive the current operating conditions of the engine, the current pressure conditions of the intake pipe,
Check the current purge condition of the single pass canister purge system based on the single purge map,
Control method of the canister purge system for controlling the purge control valve according to the identified current purge conditions. The method according to claim 2,
The single purge map has a negative pressure purge region, a transition region, and a single purge incapable region divided according to an operating condition of an engine and a pressure condition of an intake pipe,
The negative pressure purge area is an area where the evaporation gas moves to the downstream side of the throttle valve, the transition area is an area where valve chattering can occur, and the single purge non-disabled area is an area where the evaporation gas cannot move to the downstream side of the throttle valve. Control method of canister purge system. The method according to claim 3,
The single purge map is mapped by a combination of a first pressure map and a second pressure map,
The first pressure map is a map in which inlet pressure of the intake pipe is mapped according to engine load and engine speed, and the second pressure map is a map in which the pressure of the surge tank according to the engine load and engine speed is mapped. Control method. The method according to claim 1,
The dual purge mode,
Check the current opening and closing state of the purge control valve,
Receive the current operating conditions of the engine, the current pressure conditions of the intake pipe,
Confirm the current purge condition of the dual pass canister purge system based on the dual purge map,
Control method of the canister purge system for controlling the purge control valve according to the identified current purge conditions. The method according to claim 5,
After receiving the current operating conditions of the engine, calculate the surge margin ratio corresponding to the current operating conditions of the engine,
A control method of a canister purge system that closes the purge control valve when the surge margin rate satisfies a surge generation condition. The method according to claim 6,
If the surge margin rate does not satisfy the surge generation condition, check the current purge condition of the dual pass canister purge system based on the dual purge map,
Control method of the canister purge system for controlling the purge control valve according to the identified current purge conditions. The method according to claim 7,
The dual purge map has a negative pressure purge region, a mixed purge region, a transition region, and a boost purge region divided according to an engine operating condition and an intake pipe pressure condition,
The negative pressure purge area is an area where the evaporation gas moves only to the downstream side of the throttle valve, and the mixed purge area is capable of moving the evaporation gas at a relatively high rate to the downstream side of the throttle valve and a relatively small rate to the upstream side of the compressor. The region, the transition region is a region where valve chattering can occur, and the boost purge region is a region in which the evaporated gas moves only upstream of the compressor. The method according to claim 8,
The dual purge map is mapped by a combination of a first pressure map, a second pressure map, and a third pressure map,
The first pressure map is a map in which inlet pressure of an intake pipe is mapped according to engine load and engine speed, and the second pressure map is a map in which pressure of a surge tank is mapped according to engine load and engine speed. 3 The pressure map is a control method of the canister purge system, which is a map where boost pressure is mapped according to engine load and engine speed. The method according to claim 9,
The dual purge map includes a surge generation area where a surge of the compressor can occur, and the surge generation area is a control method of a canister purge system defined by a threshold line of a surge margin rate for determining whether a surge of the compressor is generated.

Images