JP6100148B2 - Evaporative fuel processing equipment - Google Patents

Description

  The present invention relates to an evaporative fuel processing apparatus including a canister that includes an adsorbent that adsorbs evaporative fuel generated in a fuel tank of a vehicle, and a block valve provided in a vapor passage that connects the canister and the fuel tank. .

A conventional evaporative fuel processing apparatus related to this is described in Patent Document 1.
The evaporative fuel processing apparatus of Patent Document 1 includes a blocking valve (control valve) in a vapor passage that connects a canister and a fuel tank. The blocking valve includes a dead zone area (valve closing area) for blocking evaporated fuel and a conduction area (valve opening area) for allowing evaporated fuel to pass, and holds the fuel tank in a closed state in the closed state, In the open state, the fuel tank evaporative fuel is allowed to escape to the canister side, and the internal pressure of the fuel tank can be reduced.
The evaporative fuel processing apparatus of Patent Document 1 changes the opening degree of the blocking valve from the closed position to the opening direction at a predetermined speed, and opens the opening degree of the blocking valve when the internal pressure of the fuel tank starts to decrease. Learning control stored as the start position is performed.

JP2011-256778A

  In order to learn the valve opening start position of the blocking valve with high accuracy, it is necessary to slowly change the opening of the blocking valve in the opening direction. However, in the above-described evaporative fuel processing device, since the opening degree of the blocking valve is changed from the closing position to the opening direction at a predetermined speed, learning control is performed when trying to learn the opening position of the closing valve with high accuracy. It takes time.

  The present invention has been made to solve the above-described problems, and the problem to be solved by the present invention is that learning control for learning the valve opening start position of the blocking valve can be performed with high accuracy in a short time. Is to do.

The above-described problems are solved by the inventions of the claims.
The invention according to claim 1 is an evaporated fuel comprising a canister having an adsorbent that adsorbs evaporated fuel generated in a fuel tank of a vehicle, and a block valve provided in a vapor passage connecting the canister and the fuel tank. The sealing valve is capable of holding the fuel tank in a closed state when the stroke amount, which is the axial distance of the movable portion of the valve relative to the valve seat, is within a predetermined range from zero. The valve opening start position can be learned on the basis of the stroke amount when the internal pressure of the fuel tank is decreased by a predetermined value or more by changing the stroke amount in the valve opening direction. In learning of the valve start position, learning is performed by changing the stroke amount of the valve movable portion in the valve opening direction from a value smaller by a predetermined stroke than the valve opening start position learned last time. And butterflies.

  According to the present invention, in learning of the valve opening start position of the blocking valve, learning is performed by changing the stroke amount of the valve movable portion in the valve opening direction from a value smaller than the valve opening start position learned last time by a predetermined amount. That is, until the valve learning start position learned last time is smaller than the valve opening start position by a predetermined amount (stroke amount), the valve movable portion is quickly changed in the valve opening direction, and then the stroke amount of the valve movable portion is slowly opened. You can learn by changing the direction. As described above, since the valve movable portion is slowly changed in the valve opening direction only in the vicinity of the valve opening start position, highly accurate learning can be performed in a short time.

According to the invention of claim 2, it is determined that the tank is unstable during the operation in which the fluctuation of the liquid level in the fuel tank is determined to be greater than that during normal driving of the vehicle, and learning of the opening start position of the blocking valve is performed. Is prohibited.
Here, for example, sudden acceleration / deceleration operations (throttle opening, acceleration sensor, brake pedaling force, etc.) may be used to determine that the fluctuation of the liquid level in the fuel tank is greater than that during normal driving of the vehicle. Detection), turning operation (detected by the steering angle), rough road travel (detected by the internal pressure of the shock absorber), travel on a slope (detected by the tilt of the vehicle body), receiving a gust of wind (detected by navigation enhancement), and the like.
As described above, when it is determined that the fluctuation of the liquid level in the fuel tank is larger than that during normal driving of the vehicle, generally, evaporated fuel is generated in the fuel tank, and the internal pressure of the fuel tank increases. To do. For this reason, the internal pressure of the fuel tank may not decrease even if the opening of the blocking valve is started when learning the opening start position of the blocking valve. Therefore, when it is determined that the fluctuation of the liquid level in the fuel tank is larger than that during normal driving of the vehicle, it is not necessary to detect the internal pressure of the fuel tank. Is prohibited. Thereby, mislearning can be prevented.

According to the invention of claim 3, the internal pressure of the fuel tank is detected, and when the amount of change in the internal pressure within the reference time exceeds a predetermined value, it is determined that the tank is in an unstable state, and learning of the opening start position of the blocking valve is performed. Is prohibited.
That is, if the amount of change in the internal pressure of the fuel tank within the reference time is greater than or equal to a predetermined value, the internal pressure of the fuel tank may not decrease even if the closing valve is opened during learning. Therefore, in this case, learning of the valve opening start position of the blocking valve is prohibited, so that erroneous learning can be prevented.
According to the invention of claim 4, after determining that the tank is unstable, it is determined that the tank is stable when the amount of change in the internal pressure within the reference time is lower than a predetermined value. It is characterized by learning.
According to the invention of claim 5, the pressure difference is obtained by detecting the internal pressure of the fuel tank at regular intervals, and if the state where the pressure difference is not less than a predetermined value continues for the first predetermined time, it is determined that the tank is unstable. When the state where the differential pressure is smaller than a predetermined value continues for a second predetermined time, it is determined that the tank is in a stable state.
According to a sixth aspect of the present invention, the tank is determined to be in a stable state when the vehicle is stopped or when the motor of the hybrid vehicle is running.
Thereby, the learning of the valve opening start position of the blocking valve can be performed with high accuracy.

According to the seventh aspect of the present invention, when it is determined that the learned value of the valve opening start position of the block valve is incorrect, the learned value is reset, and the valve opening start position of the block valve from the zero stroke amount position. It is characterized by learning.
For this reason, the block valve is not used on the basis of an erroneous learning value, and the internal pressure control of the fuel tank and the air-fuel ratio control of the engine do not become unstable.
The invention according to claim 8 is characterized in that it is determined whether or not the learning value is incorrect based on the internal pressure of the fuel tank when the blocking valve is opened.
That is, if the learning value of the valve opening start position of the blocking valve is incorrect, the internal pressure control of the fuel tank becomes unstable, so the learning value is based on the internal pressure of the fuel tank when the blocking valve is opened. It can be determined whether or not is incorrect.
The invention according to claim 9 is characterized in that it is determined whether or not the learning value is incorrect based on the air-fuel ratio signal of the engine when the blocking valve is opened.
That is, if the learned value of the valve opening start position of the block valve is incorrect, the air-fuel ratio control of the vehicle engine becomes unstable, so it is determined whether the learned value is incorrect based on the air-fuel ratio signal. Can do.

According to the invention of claim 10, every time the closing valve is opened a predetermined number of times, the valve opening start position of the blocking valve is learned from the zero stroke amount position, and the previous learning value is reset.
In this way, by periodically learning the opening start position of the blocking valve, the blocking valve can be used in a normal state.
According to an eleventh aspect of the present invention, the blocking valve controls a stroke amount, which is an axial distance of the valve movable portion with respect to the valve seat, using a screwing action of a screw.
For this reason, the stroke amount of the valve movable portion can be accurately grasped from the rotation angle of the screw.

  According to the present invention, learning control for learning the valve opening start position of the blocking valve can be performed with high accuracy in a short time.

1 is an overall configuration diagram of an evaporated fuel processing apparatus according to Embodiment 1 of the present invention. It is a longitudinal cross-sectional view showing the initialization state of the blocking valve used with the said fuel vapor processing apparatus. It is a longitudinal cross-sectional view showing the valve closing state of the said blocking valve. It is a longitudinal cross-sectional view showing the valve opening state of the said blocking valve. It is a graph showing the learning control which learns the valve opening start position of the said blocking valve. FIG. 6 is an enlarged view taken along arrow VI in FIG. 5. It is a graph showing the change of the internal pressure of a fuel tank, and a pressure detection timing. It is a flowchart which discriminate | determines the tank stable state of a fuel tank, and a tank unstable state based on the graph of FIG. It is a graph showing the change of the internal pressure of a fuel tank, the operation | movement of a stability determination counter, an instability determination counter, etc. FIG. 10 is a flowchart for determining a tank stable state and a tank unstable state of a fuel tank based on the graph of FIG. 9.

[Embodiment 1]
Hereinafter, the evaporated fuel processing apparatus 20 according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 10. As shown in FIG. 1, the fuel vapor processing apparatus 20 of this embodiment is provided in a vehicle engine system 10, and prevents fuel vapor generated in a fuel tank 15 of the vehicle from leaking outside. Device.

<About the structure outline of the evaporative fuel processing apparatus 20>
As shown in FIG. 1, the evaporated fuel processing apparatus 20 includes a canister 22, a vapor passage 24 connected to the canister 22, a purge passage 26, and an atmospheric passage 28.
Activated carbon (not shown) as an adsorbent is loaded in the canister 22 so that the evaporated fuel in the fuel tank 15 can be adsorbed by the adsorbent.
One end portion (upstream end portion) of the vapor passage 24 is communicated with an air layer portion in the fuel tank 15, and the other end portion (downstream end portion) of the vapor passage 24 is communicated with the inside of the canister 22. . A sealing valve 40 (described later) that communicates and blocks the vapor passage 24 is interposed in the vapor passage 24.
One end (upstream end) of the purge passage 26 communicates with the inside of the canister 22, and the other end (downstream end) of the purge passage 26 is connected to the throttle valve 17 in the intake passage 16 of the engine 14. Is also communicated with the downstream passage. In the middle of the purge passage 26, a purge valve 26v for communicating and blocking the purge passage 26 is interposed.
Further, the canister 22 is connected to the atmospheric passage 28 through an OBD component 28v used for failure detection. An air filter 28a is interposed in the middle of the atmospheric passage 28, and the other end of the atmospheric passage 28 is open to the atmosphere.
The block valve 40, the purge valve 26v, and the OBD component 28v are controlled based on a signal from the ECU 19.
Further, a signal from a tank internal pressure sensor 15p for detecting the pressure in the fuel tank 15 is input to the ECU 19.

<About operation | movement outline | summary of the evaporative fuel processing apparatus 20>
Next, the basic operation of the evaporated fuel processing apparatus 20 will be described.
While the vehicle is parked, the blocking valve 40 is kept closed. For this reason, the evaporated fuel in the fuel tank 15 does not flow into the canister 22. When the ignition switch of the vehicle is turned on during parking, learning control for learning the valve opening start position of the blocking valve 40 is performed (described later).
Further, while the vehicle is parked, the purge valve 26v is kept closed, the purge passage 26 is shut off, and the air passage 28 is kept in communication.
During traveling of the vehicle, the ECU 19 executes control to purge the evaporated fuel adsorbed by the canister 22 when a predetermined purge condition is satisfied. In this control, the purge valve 26v is controlled to open and close while the canister 22 is in communication with the atmosphere through the atmosphere passage 28. When the purge valve 26v is opened, the intake negative pressure of the engine 14 acts in the canister 22 via the purge passage 26. As a result, air flows from the atmospheric passage 28 into the canister 22. Further, when the purge valve 26v is opened, the block valve 40 operates in the valve opening direction, and the pressure relief control of the fuel tank 15 is performed. As a result, the gas in the fuel tank 15 flows into the canister 22 from the vapor passage 24. As a result, the adsorbent in the canister 22 is purged by air or the like flowing into the canister 22, and the evaporated fuel separated from the adsorbent is guided to the intake passage 16 of the engine 14 together with air and burned in the engine 14. .

<About the basic structure of the blocking valve 40>
The block valve 40 is a flow rate control valve that blocks the vapor passage 24 in the closed state and controls the flow rate of the gas flowing through the vapor passage 24 in the open state. As shown in FIG. 2, the valve casing 42 and the stepping motor 50, a valve guide 60 and a valve body 70.
The valve casing 42 includes a valve chamber 44, an inflow path 45, and an outflow path 46, thereby forming a series of inverted L-shaped fluid passages 47. A valve seat 48 is formed concentrically on the lower surface of the valve chamber 44, that is, on the mouth edge of the upper end opening of the inflow passage 45.
The stepping motor 50 is installed on the valve casing 42. The stepping motor 50 has a motor main body 52 and an output shaft 54 that protrudes from the lower surface of the motor main body 52 and is configured to be rotatable forward and backward. The output shaft 54 is disposed concentrically within the valve chamber 44 of the valve casing 42, and a male screw portion 54 n is formed on the outer peripheral surface of the output shaft 54.

The valve guide 60 is formed in a cylindrical cylindrical shape from a cylindrical cylindrical wall portion 62 and an upper wall portion 64 that closes the upper end opening of the cylindrical wall portion 62. A cylindrical shaft portion 66 is formed concentrically at the center of the upper wall portion 64, and a female screw portion 66 w is formed on the inner peripheral surface of the cylindrical shaft portion 66. The valve guide 60 is disposed so as to be movable in the axial direction (vertical direction) with respect to the valve casing 42 in a state in which the valve guide 42 is prevented from rotating in the direction around the axis by a detent means (not shown).
A male threaded portion 54n of the output shaft 54 of the stepping motor 50 is screwed into the female threaded portion 66w of the cylindrical shaft portion 66 of the valve guide 60, and based on forward and reverse rotation of the output shaft 54 of the stepping motor 50. The valve guide 60 is configured to be movable up and down in the vertical direction (axial direction).
Around the valve guide 60, an auxiliary spring 68 for biasing the valve guide 60 upward is interposed.

The valve body 70 is formed in a bottomed cylindrical shape from a cylindrical tube wall portion 72 and a lower wall portion 74 that closes a lower end opening of the tube wall portion 72. A seal member 76 made of, for example, a disk-like rubber-like elastic material is attached to the lower surface of the lower wall portion 74.
The valve body 70 is disposed concentrically within the valve guide 60, and the seal member 76 of the valve body 70 is disposed so as to be able to contact the upper surface of the valve seat 48 of the valve casing 42. On the outer peripheral surface of the upper end of the cylindrical wall portion 72 of the valve body 70, a plurality of connecting projections 72t are formed in the circumferential direction. And the connection convex part 72t of the valve body 70 is fitted to the longitudinally grooved connection concave part 62m formed on the inner peripheral surface of the cylindrical wall part 62 of the valve guide 60 in a state where it can be relatively moved in the vertical direction by a certain dimension. ing. The valve guide 60 and the valve body 70 are integrally and upwardly (in the valve opening direction) with the bottom wall portion 62b of the connection recess 62m of the valve guide 60 in contact with the connection protrusion 72t of the valve body 70 from below. ) Can be moved.
Further, a valve that constantly urges the valve body 70 downward, that is, in a valve closing direction with respect to the valve guide 60, between the upper wall portion 64 of the valve guide 60 and the lower wall portion 74 of the valve body 70. A spring 77 is interposed concentrically.

<About the basic operation of the block valve 40>
Next, the basic operation of the blocking valve 40 will be described.
The blocking valve 40 rotates the stepping motor 50 by a predetermined number of steps in the valve opening direction or the valve closing direction based on the output signal from the ECU 19. Then, the stepping motor 50 rotates by a predetermined number of steps, so that the male screw portion 54n of the output shaft 54 of the stepping motor 50 and the female screw portion 66w of the tube shaft portion 66 of the valve guide 60 are screwed together. The valve guide 60 moves in a vertical direction by a predetermined stroke amount.
In the blocking valve 40, for example, the number of steps is set to about 200 Step and the stroke amount is set to about 5 mm in the fully opened position.
In the initialized state (initial state) of the blocking valve 40, as shown in FIG. 2, the valve guide 60 is held at the lower limit position, and the lower end surface of the cylindrical wall portion 62 of the valve guide 60 is the valve seat 48 of the valve casing 42. It is in contact with the upper surface of. In this state, the connecting projection 72 t of the valve body 70 is positioned above the bottom wall 62 b of the connecting recess 62 m of the valve guide 60, and the seal member 76 of the valve body 70 is connected to the valve spring 77. It is pressed against the upper surface of the valve seat 48 of the valve casing 42 by the spring force. That is, the blocking valve 40 is held in a fully closed state. At this time, the number of steps of the stepping motor 50 is 0 Step, and the movement amount of the valve guide 60 in the axial direction (upward direction), that is, the stroke amount in the valve opening direction is 0 mm.
Further, when the vehicle is parked or the like, the stepping motor 50 of the blocking valve 40 rotates, for example, 4 Steps in the valve opening direction from the initialized state. As a result, the valve guide 60 moves upward by about 0.1 mm by the screwing action of the male threaded portion 54n of the output shaft 54 of the stepping motor 50 and the female threaded portion 66w of the cylindrical shaft portion 66 of the valve guide 60, and the valve casing 42 The valve seat 48 is held in a floating state. This makes it difficult to apply an excessive force between the valve guide 60 of the blocking valve 40 and the valve seat 48 of the valve casing 42 due to environmental changes such as temperature.
In this state, the seal member 76 of the valve body 70 is pressed against the upper surface of the valve seat 48 of the valve casing 42 by the spring force of the valve spring 77.

When the stepping motor 50 further rotates in the valve opening direction from the position rotated by 4 Steps, the valve guide 60 moves upward by the screwing action of the male screw portion 54n and the female screw portion 66w, and as shown in FIG. The bottom wall portion 62b of the connection recess 62m of the guide 60 abuts on the connection projection 72t of the valve body 70 from below. As the valve guide 60 further moves upward, the valve body 70 moves upward together with the valve guide 60 as shown in FIG. 4, and the seal member 76 of the valve body 70 moves from the valve seat 48 of the valve casing 42. Get away. Thereby, the blocking valve 40 is opened.
Here, the valve opening start position of the sealing valve 40 is determined by the position tolerance of the connecting convex portion 72t formed in the valve body 70, the position tolerance of the bottom wall portion 62b formed in the connecting concave portion 62m of the valve guide 60, and the like. Since each valve 40 is different, it is necessary to accurately learn the valve opening start position. This learning is performed in the learning control, and the valve opening is started based on the timing when the internal pressure of the fuel tank 15 decreases by a predetermined value or more while rotating the stepping motor 50 of the blocking valve 40 in the valve opening direction (increasing the number of steps). The number of position steps is detected.
Thus, when the closing valve 40 is in the closed state, the valve guide 60 corresponds to the valve movable portion of the present invention, and when the closing valve 40 is in the opened state, the valve guide 60 and the valve body 70 are in the present invention. It corresponds to the valve moving part.

<Regarding learning control of a general block valve 40>
Next, learning control of the valve opening start position of the general block valve 40 will be described based on FIGS. 5 and 6.
The learning control is performed at a rate of once every time the blocking valve 40 is opened a predetermined number of times. The learning control is performed when the state of the fuel tank 15 is determined to be stable (tank stable state), such as when the ignition switch of the vehicle engine is turned on.
Here, the upper diagram of FIG. 5 represents the change in the number of steps of the stepping motor 50 with respect to time (horizontal axis), that is, the stroke amount (amount of movement in the axial direction) of the valve guide 60 and the valve body 70. Yes. For this reason, the number of steps and the stroke amount will be used as synonyms hereinafter.
Further, the lower diagram of FIG. 5 represents a change in the internal pressure (tank internal pressure) of the fuel tank 15 with time as a reference (horizontal axis). Here, the tank internal pressure is detected at regular intervals.
As described above, when the vehicle is parked, the stepping motor 50 is rotated in the valve opening direction, for example, by 4 Steps, and the valve guide 60 is held in a state of being lifted about 0.1 mm from the valve seat 48 of the valve casing 42. When the ignition switch of the engine is turned on in this state, the stepping motor 50 rotates 4 steps (−4 steps) in the valve closing direction, and the block valve 40 is returned to the initialized state (0 step). Next, as shown in the upper diagram of FIG. 5, the stepping motor 50 returns to the valve closing limit position S0 (S0 = Sx−) from the previous valve opening start position (previous learning value Sx) of the blocking valve 40 by a predetermined step ZStep. Rotate at high speed in the valve opening direction until Z).

As a result, the valve guide 60 moves upward to the valve closing limit position S0 relatively quickly, and the learning time can be shortened. At this time, the seal member 76 of the valve body 70 is in contact with the upper surface of the valve seat 48 of the valve casing 42 by the spring force of the valve spring 77, and the closing valve 40 is in a closed state.
Then, when the stepping motor 50 rotates in the valve opening direction to the valve closing limit position S0 (S0 = Sx−Z) Step of the blocking valve 40, the stepping motor 50 stops and, as shown in the upper diagram of FIG. This state is maintained by T. The tank internal pressure is detected while the stepping motor 50 is stopped. If the tank internal pressure has not decreased by a predetermined value (ΔP1) or more with respect to the previous detection value, the valve closing limit position S0 (S0 = Sx−Z) Step is stored as the stroke amount.
Next, as shown in the upper diagram of FIG. 6, the stepping motor 50 rotates in the valve opening direction by AStep (for example, 2Step) and is maintained for a certain time T, during which the tank internal pressure is detected. At this time, if the tank internal pressure has not decreased by a predetermined value (ΔP1) or more with respect to the previous detection value, a value obtained by adding the current stroke amount (AStep) to the previous stroke amount S0Step is stored as a new stroke amount. The That is, the stroke amount is updated from S0Step to (S0 + A) Step.
When such a process is repeatedly executed and the tank internal pressure detected this time has decreased by a predetermined value (ΔP1) or more with respect to the previous detection value, it is determined that the closing valve 40 has started to be opened. The As a result, the learning flag is turned on (not shown), and a value obtained by adding (A-1) Step to the stroke amount S4 updated in the previous step is stored as a learning value of the valve opening start position, and learning control is performed. Ends.

<Regarding the learning prohibition condition of the blocking valve 40>
Next, the learning prohibition determination of the blocking valve 40 will be described with reference to FIGS.
For example, when the amount of evaporated fuel generated in the fuel tank 15 is large and the amount of increase in internal pressure is large, such as immediately after the engine is stopped after a high load, the opening of the block valve 40 is started by learning control. In some cases, the internal pressure of the fuel tank 15 does not decrease by a predetermined value (ΔP1) or more. Under such conditions, it is not possible to accurately learn the valve opening start position of the blocking valve 40, and thus it is necessary to prohibit learning control.
In the fuel vapor processing apparatus 20 according to the present embodiment, the learning prohibition condition is determined based on the flowchart shown in FIG. Here, the process shown in the flowchart of FIG. 8 is repeatedly executed at predetermined intervals based on a program stored in the storage device of the ECU 19.
First, in step S101 of FIG. 8, the internal pressure P1 of the fuel tank 15 is read (see FIG. 7), and the counter Cnt is started in step S102. Next, after the counter Cnt is started, for example, the internal pressure P2 of the fuel tank 15 is read at a timing when T1 = 500 ms has elapsed (step S103). Then, a differential pressure between the tank internal pressure P1 and the tank internal pressure P2 is calculated to obtain a differential pressure ΔP (= P2−P1) (step S104), and the differential pressure ΔP is set to a predetermined value B (for example, B = 0.1 kPa). Compare (step S105). When the differential pressure ΔP is smaller than the predetermined value B (step S105 YES), it is determined that the tank is in a stable state (step S106). When it is determined that the tank is in a stable state, learning control of the valve opening start position of the blocking valve 40 is permitted.
If the differential pressure ΔP is greater than the predetermined value B (NO in step S105), it is determined that the tank is unstable (step S107). When it is determined that the tank is unstable, learning control of the opening start position of the blocking valve 40 is prohibited.
Here, even if it is determined that the tank is stable and learning control of the opening start position of the blocking valve 40 is performed, the internal pressure fluctuation of the fuel tank 15 increases during the opening operation of the closing valve 40, or If it is detected that the air-fuel ratio of the engine has become unstable, it is determined that the valve opening start position of the block valve 40 has been mislearned, and the next learning control is immediately performed to reset the previous learning value. .

Next, the learning prohibition determination of the blocking valve 40 according to the modified example will be described based on FIGS.
Here, the process shown in the flowchart of FIG. 10 is repeatedly executed at predetermined intervals based on a program stored in the storage device of the ECU 19.
In the process shown in the flowchart of FIG. 10, first, the unstable counter CntT1 starts in step S201. Next, time determination after the unstable counter CntT1 is started is performed (step S202). Immediately after the start of the unstable counter CntT1, the time determination in step S202 is YES, so the process proceeds to step S203 to step S205, where the tank internal pressure (Pn) detected this time and the tank internal pressure (Pn-1) detected last time are Is calculated. If the differential pressure ΔP is, for example, greater than 0.1 kPa (NO in step S206), the stability counter CntT2 is reset (step S212), and the process returns to step S201.
In a state where the change in the tank internal pressure is large (see Pn-3 to Pn-1 in FIG. 9), the processing from step S201 to step S212 is repeatedly executed. When the value of the unstable counter CntT1 becomes larger than, for example, 3 seconds (NO in step S202), it is determined that the tank is unstable (unstable determination) (step S214). Thereby, learning control of the valve opening start position of the blocking valve 40 is prohibited.

Further, when the differential pressure ΔP becomes smaller than, for example, 0.1 kPa (step S206 YES) while the processes from step S201 to step S212 are being repeatedly executed, the stability counter CntT2 starts (step S207). In step S208, it is determined whether or not the stable counter CntT2 has passed, for example, 500 ms or more. Immediately after the start of the stability counter CntT2, since 500 ms or more has not elapsed (NO in step S208), the process returns to step S201. When the change in the tank internal pressure is small (see Pn to Pn + 4 in FIG. 9), when the processing from step S201 to step S208 is repeatedly executed and the value of the stability counter CntT2 becomes 500 msec or more (step S208 YES), FIG. As shown in the figure below, the stability flag is turned on and it is determined that the tank is in a stable state (stability determination) (step S209). Thereby, the unstable counter CntT1 is reset (step S210).
And learning control of the valve opening start position of the blocking valve 40 is permitted by determining with the tank stable state.

<Advantages of the evaporated fuel processing apparatus 20 according to the present embodiment>
According to the fuel vapor processing apparatus 20 according to the present embodiment, when learning the valve opening start position of the blocking valve 40, the predetermined step ZStep is returned from the previously learned valve opening start position (previous learning value Sx). Learning is performed by changing the valve guide 60 (valve movable portion) from the valve closing limit position S0 (S0 = Sx−Z) in the valve opening direction. That is, the valve guide 60 (valve movable part) is quickly moved to the valve closing limit position S0 (S0 = Sx−Z) that has returned by a predetermined step ZStep from the previously learned valve opening start position (previous learning value Sx). Learning can be performed by changing the valve opening direction, and then slowly changing the stroke amount of the valve guide 60 (valve movable portion) in the valve opening direction. Thus, since the valve guide 60 (valve movable part) is slowly changed in the valve opening direction only in the vicinity of the valve opening start position, highly accurate learning can be performed in a short time.
Further, as shown in FIG. 7, when the internal pressure of the fuel tank 15 is detected and the internal pressure change amount ΔP with respect to the reference time T1 is equal to or greater than a predetermined value (0.1 kPa), it is determined that the tank is unstable. Since learning of the valve opening start position of 40 is prohibited, erroneous learning can be prevented.

Further, as shown in FIG. 9, the internal pressure of the fuel tank 15 is detected at regular time intervals to obtain a differential pressure ΔP, and a state where the differential pressure ΔP is equal to or greater than a predetermined value (0.1 kPa) is a first predetermined time (for example, 3 sec. ) When it is continued, it is determined that the tank is unstable. When the state where the differential pressure ΔP is smaller than a predetermined value (0.1 kPa) continues for a second predetermined time (for example, 500 msec), it is determined that the tank is stable.
For this reason, the accuracy of determining whether the internal pressure of the fuel tank 15 is stable or unstable is increased.
Further, since the closing valve 40 is configured to adjust the flow rate by controlling the stroke amount of the valve guide 60 (valve movable portion) with respect to the valve seat 48 using the screwing action of the screw, the rotation angle of the screw Therefore, the stroke amount of the valve guide 60 (valve movable portion) can be accurately grasped.
Further, based on the internal pressure of the fuel tank 15 when the closing valve 40 is opened or the air-fuel ratio signal of the engine, it is determined whether or not the learning value is incorrect, and the opening start position of the closing valve 40 is determined. If it is determined that the learning value is incorrect, the learning value is reset. For this reason, the blocking valve 40 is not used based on an erroneous learning value, and the internal pressure control of the fuel tank 15 and the air-fuel ratio control of the engine do not become unstable.

<Example of change>
The present invention is not limited to the above-described embodiment, and modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, an example in which the tank stable state or the tank unstable state is determined from the change in the internal pressure of the fuel tank 15 has been described. However, without monitoring the change in the internal pressure of the fuel tank 15 in particular, the tank is determined to be in an unstable state at the time of operation in which it is determined that the fluctuation of the liquid level in the fuel tank 15 becomes larger than that during normal driving of the vehicle. It is also possible to prohibit learning of the opening start position of the blocking valve.
Here, for an operation that is judged that the fluctuation of the liquid level in the fuel tank 15 becomes larger than that during normal driving of the vehicle, for example, sudden acceleration / deceleration operations (throttle opening, acceleration sensor, brake pedal force, etc.) ), Turning motion (detected by steering angle), rough road traveling (detected by internal pressure of shock absorber), traveling on slope (detected by vehicle body tilt), receiving gust of wind (detected by navigation enhancement), and the like.
As described above, when it is determined that the fluctuation of the liquid level in the fuel tank 15 becomes larger than that during normal driving of the vehicle, evaporative fuel is generally generated in the fuel tank 15. The internal pressure increases. Therefore, it is possible to prevent erroneous learning by prohibiting learning of the valve opening start position of the blocking valve 40 when it is determined that the fluctuation of the liquid level in the fuel tank 15 is larger than that during normal driving of the vehicle. Further, when the vehicle is stopped or when the hybrid vehicle is running, it is generally possible to determine that the tank is in a stable state and to learn the valve opening start position of the blocking valve 40.
Moreover, in this embodiment, the example which performs learning control of the valve opening start position of the sealing valve 40 by the rate of once is shown every time the sealing valve 40 is opened a predetermined number of times. However, it is possible to perform the learning control and reset the previous learning value every time the blocking valve 40 is opened. Thereby, the blocking valve 40 can always be used in a normal state.
In the present embodiment, an example in which the stepping motor 50 is used as the motor of the blocking valve 40 has been described. However, a DC motor or the like can be used instead of the stepping motor 50.

15 ... Fuel tank 22 ... Canister 24 ... Vapor passage 40 ... Sealing valve 48 ... Valve seat 54 ... Output shaft 54n ... Male thread 60 / ... Valve guides (valve moving parts)
66 ··· cylinder shaft portion 66w ... female screw portion 70 ··· valve body (valve movable portion)

Claims (11)

An evaporative fuel processing apparatus comprising: a canister that includes an adsorbent that adsorbs evaporative fuel generated in a fuel tank of a vehicle; and a block valve provided in a vapor passage that connects the canister and the fuel tank,
The block valve is capable of holding the fuel tank in a closed state when the stroke amount, which is the axial distance of the movable portion of the valve with respect to the valve seat, is within a predetermined range from zero. The valve opening start position can be learned based on the stroke amount when the internal pressure of the fuel tank is decreased by a predetermined value or more by changing in the valve direction,
In the learning of the valve opening start position of the blocking valve, the learning is performed by changing the stroke amount of the valve movable portion in the valve opening direction from a value smaller by a predetermined stroke than the valve opening start position learned last time. Evaporative fuel processing device. The evaporative fuel processing apparatus according to claim 1,
It is determined that the tank is unstable during an operation in which the fluctuation of the liquid level in the fuel tank is determined to be greater than that during normal driving of the vehicle, and learning of the opening position of the closing valve is prohibited. Evaporative fuel processing device. An evaporative fuel processing apparatus according to claim 1 or 2, wherein
The internal pressure of the fuel tank is detected, and when the amount of change in internal pressure within a reference time exceeds a predetermined value, it is determined that the tank is in an unstable state, and learning of the valve opening start position of the blocking valve is prohibited. Evaporative fuel processing device. The evaporative fuel processing apparatus according to claim 3,
After determining that the tank is in an unstable state, it is determined that the tank is in a stable state when the amount of change in internal pressure within a reference time is lower than the predetermined value , and learning of the valve opening start position of the blocking valve becomes possible. An evaporative fuel processing apparatus characterized by the above. An evaporative fuel processing apparatus according to claim 3, wherein:
A differential pressure is determined by detecting the internal pressure of the fuel tank at regular intervals. If the differential pressure is equal to or greater than the predetermined value continues for a first predetermined time, it is determined that the tank is unstable, and the differential pressure is determined to be the predetermined pressure. An evaporative fuel processing apparatus characterized in that a tank stable state is determined when a state smaller than the value continues for a second predetermined time. An evaporative fuel processing apparatus according to any one of claims 1 to 5,
An evaporative fuel processing apparatus characterized in that it is determined that the tank is in a stable state when the vehicle is stopped or when the motor of the hybrid vehicle is running. An evaporative fuel processing apparatus according to any one of claims 1 to 6,
When it is determined that the learning value of the valve opening start position of the block valve is incorrect, the learning value is reset, and learning of the valve opening start position of the block valve is performed from the zero stroke amount position. An evaporative fuel processing apparatus. The evaporative fuel processing device according to claim 7,
An evaporative fuel processing apparatus, wherein whether or not a learning value is incorrect is determined based on an internal pressure of a fuel tank when the blocking valve is opened. An evaporative fuel processing apparatus according to any one of claims 7 and 8,
An evaporative fuel processing apparatus, wherein whether or not a learning value is incorrect is determined based on an air-fuel ratio signal of an engine when the blocking valve is opened. An evaporative fuel processing apparatus according to any one of claims 1 to 9,
The evaporative fuel processing device is characterized in that each time the block valve is opened a predetermined number of times, the valve opening start position of the block valve is learned from a zero stroke amount position, and the previous learning value is reset. An evaporative fuel processing apparatus according to any one of claims 1 to 10,
The evaporative fuel processing device is characterized in that the blocking valve controls a stroke amount which is an axial distance of the valve movable portion with respect to the valve seat using a screwing action of a screw.

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