JP6076885B2 - Evaporative fuel processing equipment - Google Patents

Description

  The present invention relates to an evaporated fuel processing apparatus including a canister that includes an adsorbent that adsorbs evaporated fuel generated in a fuel tank, 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 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.
A first aspect of the present invention is an evaporative fuel processing apparatus comprising a canister having an adsorbent for adsorbing evaporated fuel generated in a fuel tank, and a blocking 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 based on the stroke amount when the internal pressure of the fuel tank decreases by a predetermined value or more by changing the stroke amount in the valve opening direction. In the learning of the position, the stroke amount of the valve movable portion is changed in the valve opening direction at the first speed from zero to the valve closing limit position, and after exceeding the valve closing limit position, the second speed that is slower than the first speed. so And wherein the changing the stroke amount of the movable portion in the valve opening direction.

According to the present invention, in learning of the valve opening start position of the block valve, the stroke amount of the valve movable portion is changed from zero to the valve closing limit position at the first speed, and after exceeding the valve closing limit position, the first speed is changed. The stroke amount of the valve movable part is changed at a second speed slower than the second speed.
That is, the stroke amount of the valve movable portion is changed at the first speed (high speed) from zero to the valve closing limit position (near the valve opening start position), and then the stroke amount of the valve movable portion is changed. Is changed at the second speed (low speed), so that highly accurate learning can be performed in a short time.

  According to a second aspect of the present invention, there is provided an evaporative fuel processing apparatus comprising: a canister having an adsorbent that adsorbs evaporative fuel generated in a fuel tank; 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 based on the stroke amount when the internal pressure of the fuel tank decreases by a predetermined value or more by changing the stroke amount in the valve opening direction. In the learning of the position, the stroke amount of the valve movable portion is changed from zero to the valve opening direction at the first speed, and after the internal pressure of the fuel tank has dropped by a predetermined value or more, the stroke amount is closed. Previously defined amount only varied, then characterized by changing the stroke amount of the valve movable portion at a slower than the first speed second speed in the opening direction.

According to the invention of claim 2, in learning of the valve opening start position of the blocking valve, the stroke amount of the valve movable portion is changed from zero to the valve opening direction at the first speed, and the internal pressure of the fuel tank is decreased by a predetermined value or more. Thereafter, the stroke amount is changed by a predetermined amount in the valve closing direction, and thereafter, the stroke amount of the valve movable portion is changed in the valve opening direction at a second speed slower than the first speed.
That is, after changing the stroke amount of the valve movable portion from zero to the first speed (high speed) to give a guide for the valve opening start position, the stroke amount of the valve movable portion is changed to the second speed (near the valve opening start position). Because it changes at a low speed), highly accurate learning can be performed in a short time.

According to the invention of claim 3, when learning the valve opening start position of the blocking valve, when the stroke amount of the valve movable portion is changed in the valve opening direction at the second speed, it is changed in the valve opening direction by the first predetermined stroke. And repeating the step of changing in the valve closing direction by a second predetermined stroke smaller than the first predetermined stroke, and the valve movable part is moved in the step when the internal pressure of the fuel tank has dropped by a predetermined value or more, or in the previous step. (2) The valve opening start position is determined based on the stroke amount when the valve is changed in the valve closing direction by a predetermined stroke.
In this way, because the valve moving part is moved alternately in the valve opening direction and the valve closing direction, the stroke amount of the valve moving part is changed in the valve opening direction. It will be returned to the closing direction from the opened state. For this reason, the responsiveness of the internal pressure change in the fuel tank is improved, the time lag between the actual valve opening start time and the valve opening start determination time (fuel tank internal pressure drop detection timing) is reduced, and learning accuracy is improved. be able to.

According to the invention of claim 4, learning of the valve opening start position of the blocking valve is performed every time the ignition switch of the engine is turned on.
For this reason, even if the previous learning value is an erroneous learning, the adverse effect can be minimized. Moreover, the influence of the deviation of the learning value due to the replacement of parts is eliminated.

  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 a graph I showing learning control of the VI arrow portion of FIG. 5. FIG. 6 is a graph II showing learning control of the VI arrow portion of FIG. It is a graph showing the learning control which concerns on the example of a change. It is a graph showing the learning control which concerns on the example of a change.

[Embodiment 1]
Hereinafter, the evaporated fuel processing apparatus 20 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 9. 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 the blocking valve 40>
Next, learning control of the valve opening start position of the blocking valve 40 will be described with reference to FIGS.
The learning control is performed when the ignition switch of the engine is turned on while the vehicle is parked.
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 rotates at high speed in the valve opening direction to the designed valve closing limit position S0Step of the blocking valve 40. Thereby, the valve guide 60 moves upward to the valve closing limit position 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.

When the stepping motor 50 rotates in the valve opening direction to the closing limit position S0Step of the blocking valve 40, the stepping motor 50 is stopped and this state is maintained for a predetermined time T1 (see the upper diagram of FIG. 5). Next, the stepping motor 50 rotates in the valve closing direction by BStep (for example, 2Step), and this state is maintained for a certain time T2. Then, the tank internal pressure is detected at a predetermined timing while the stepping motor 50 is maintained for a predetermined time T2, for example, as shown in the upper diagram of FIG. 6, after a predetermined time T22 from the stop of the stepping motor 50. If the detected tank internal pressure is not lower than the previously detected value by a predetermined value (ΔP1) or more, a value obtained by subtracting BStep (B = 2) from the valve closing limit position S0Step, that is, (S0-2). Step is stored as a stroke amount.
Next, as shown in the upper diagrams of FIGS. 5 and 6, after the stepping motor 50 rotates in the valve opening direction by AStep (for example, 4Step) and is maintained for a certain time T1, the stepping motor 50 is turned to BStep (2Step). Only in the valve closing direction and maintained for a certain time T2. The tank internal pressure is detected at a predetermined timing (after the predetermined time T22) while the stepping motor 50 is maintained for a predetermined time T2. 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, the stroke amount A in the current valve opening direction and the valve closing direction in the previous stroke amount (S0-2) Step are set. A value obtained by adding the difference (A−B = 2) Step from the stroke amount B is stored as a new stroke amount. That is, the stroke amount is updated from (S0-2) Step to S0 Step.

Then, such a process is repeatedly executed, and as shown in the tank internal pressure graph of FIG. 6, the tank internal pressure detected this time decreases by a predetermined value (ΔP1) or more with respect to the previous detection value (see timing Tx1). If it is (see timing Tx2), it is determined that the opening of the blocking valve 40 has been started. As a result, as shown in the lower diagram of FIG. 6, the learning flag is turned on at timing Tx2. As a result, as shown in the learning value graph of FIG. 6, a value obtained by adding (A−B−1 = 1) Step to the stroke amount S2 updated in the previous step (see timing Tx1) is opened. The learning value Sx of the start position is stored, and the learning control ends.
Here, the predetermined value (ΔP1), which is the amount of change in the tank internal pressure used to determine the valve opening start position of the blocking valve 40, is the variation in the characteristics of the tank internal pressure sensor 15p, the liquid in the fuel tank 15 due to vehicle running, etc. In consideration of surface fluctuation, for example, the value is set to about 0.3 kPa.
In addition, when the learning flag is turned on, an example is shown in which (A−B−1 = 1) Step is added to the stroke amount S2 updated in the previous step (see timing Tx1) to obtain the learning value Sx. However, the stroke amount is updated from S2Step to S3Step in the process where the learning flag is turned on (see timing Tx2), and the value obtained by subtracting (A−B−1 = 1) Step from the updated stroke amount S3 is stored as the learning value Sx. It is also possible to do.
As described above, the state in which the stepping motor 50 is rotated in the valve opening direction by AStep (for example, 4Step) corresponds to the state in which the valve movable portion of the present invention is changed in the valve opening direction by the first predetermined stroke. The state in which 50 is rotated in the valve closing direction by BStep (for example, 2Step) corresponds to the state in which the valve movable portion of the present invention is changed in the valve closing direction by the second predetermined stroke.

<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 valve opening position (0Step) to the valve closing limit position (S0Step) is high-speed (first speed). After the stroke amount of the valve guide 60 (valve movable part) is changed in the valve opening direction and exceeds the valve closing limit position (S0 Step), the valve guide 60 (second speed slower than the first speed) is slowly increased. The stroke amount of the valve movable part) is changed. For this reason, highly accurate learning can be performed in a short time.
Further, after exceeding the valve closing limit position (S0 Step), the valve is changed by repeating the process of changing the valve opening direction by the first predetermined stroke (4 Step) and changing the valve closing direction by the second predetermined stroke (−2 Step). Since this is a method of changing the guide 60 (valve movable portion) in the valve opening direction, at the valve opening start position of the blocking valve 40, the flow path is returned from the opened state to the closing direction. For this reason, the responsiveness of the internal pressure change in the fuel tank 15 is improved, the time lag between the actual valve opening start time and the valve opening start determination time (internal pressure drop detection timing of the fuel tank 15) is reduced, and the learning accuracy is improved. Can be improved.
Further, since the learning of the valve opening start position of the blocking valve 40 is performed every time the ignition switch of the engine is turned on, even if the previous learning value is an erroneous learning, the adverse effect can be prevented. Moreover, the influence of the deviation of the learning value due to the replacement of parts is eliminated.

<Modification 1>
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, it is determined that the opening of the blocking valve 40 is started only when the internal pressure (tank internal pressure) of the fuel tank 15 decreases by a predetermined value (ΔP1) or more with respect to the previous detection value. However, when the tank internal pressure is low, there is a case where the tank internal pressure does not decrease by a predetermined value (ΔP1) or more even when the opening of the blocking valve 40 is started. Even in such a case, in order to perform the learning control accurately, as shown in FIG. 7, when the tank internal pressure falls below a certain value (ΔP2 <ΔP1) with respect to the previous detection value, the blocking valve It is determined that there is a possibility of starting valve opening of 40, and the temporary learning flag is turned on.
That is, in the method shown in FIG. 7, after the stepping motor 50 rotates in the valve closing direction by BStep (for example, −2 Step), the detected tank internal pressure is the previous detected value ( When it is detected that the value is lower than a certain value (ΔP2) with respect to timing Tx0 (see timing Tx1), the temporary learning flag is turned on at timing Tx1.
At this time, the number of steps of the stepping motor 50 is S2Step as shown in the upper diagram of FIG. 7, but the update of the stroke amount is prohibited when the temporary learning flag is turned on. That is, the stroke amount (S1 Step) updated in the previous process is suspended. Then, when the tank internal pressure detected in the next step (timing x2) has decreased by a predetermined value (ΔP1) or more with respect to the previous detection value (see timing Tx1), the learning flag is turned on at this timing Tx2. As a result, a value obtained by adding (A−B−1 = 1) Step to the stroke amount (S1 Step) held is stored as the learned value Sx of the valve opening start position, and the learning control ends. That is, even when the tank internal pressure is low, learning control can be performed accurately.

<Modification 2>
In the present embodiment, after the stepping motor 50 rotates in the valve opening direction to the closing limit position S0Step of the blocking valve 40, the stepping motor 50 is opened by AStep (for example, 4Step) as shown in the upper diagram of FIG. An example is shown in which the valve opening start position is learned by repeating the process of monitoring in the tank by rotating in the valve direction and rotating in the valve closing direction by BStep (for example, 2Step).
However, as shown in FIG. 8, after the stepping motor 50 has rotated in the valve opening direction to the valve closing limit position S0Step of the blocking valve 40, for example, the stepping motor 50 is rotated in the valve opening direction by BStep (eg, 2Step). Thus, it is possible to learn the valve opening start position by repeating the process of detecting the tank internal pressure.

<Modification 3>
Moreover, in this embodiment, the example which rotates the stepping motor 50 at high speed to the valve closing limit position S0Step on the design of the blocking valve 40 was shown. However, as shown in FIG. 9, the stepping motor 50 is rotated at a high speed until the tank internal pressure decreases by a predetermined value (ΔP1) or more, and from the number of steps (SxStep) when the tank internal pressure decreases by a predetermined value (ΔP1) or more. It is also possible to perform the learning control described above from the return position S0 = (Sx−Y) Step after returning YStep.
That is, from the return position S0 = (Sx−Y) Step, the stepping motor 50 is rotated in the valve opening direction by AStep (for example, 4 Step), and rotated in the valve closing direction by BStep (for example, 2 Step) to detect the tank internal pressure. It is possible to learn the valve opening start position of the blocking valve 40 by repeating this process. Further, the step of rotating the stepping motor 50 from the return position S0 = (Sx−Y) Step by BStep (for example, 2Step) in the valve opening direction and monitoring the tank internal pressure is repeated, and the valve opening start position of the blocking valve 40 is set. Learning is also possible.
<Other changes>
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.

15p ··· tank pressure sensor 15 ··· fuel tank 16 ··· intake passage 22 · · · canister 24 · · · vapor passage 40 · · · block valve 48 ··· ... Valve seat 50 ... Stepping motor 60 ... Valve guide (valve movable part)
70 ... Valve body (valve movable part)

Claims (4)

An evaporative fuel processing apparatus comprising a canister having an adsorbent that adsorbs evaporative fuel generated in a fuel tank, and a block valve provided in a vapor passage connecting 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 learning of the valve opening start position of the block valve, the stroke amount of the valve movable portion is changed in the valve opening direction at a first speed from zero to the valve closing limit position, and after the valve closing limit position is exceeded, An evaporative fuel processing apparatus characterized in that the stroke amount of the valve movable portion is changed in the valve opening direction at a second speed slower than the speed. An evaporative fuel processing apparatus comprising a canister having an adsorbent that adsorbs evaporative fuel generated in a fuel tank, and a block valve provided in a vapor passage connecting 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 learning the valve opening start position of the blocking valve, the stroke amount of the valve movable portion is changed from zero to the valve opening direction at the first speed, and the internal pressure of the fuel tank is reduced by a predetermined value or more, and then the stroke amount Is changed by a predetermined amount in the valve closing direction, and thereafter, the stroke amount of the valve movable portion is changed in the valve opening direction at a second speed slower than the first speed. An evaporative fuel processing apparatus according to claim 1 or 2, wherein
In learning the valve opening start position of the blocking valve, when changing the stroke amount of the valve movable portion in the valve opening direction at the second speed, the valve opening direction is changed by the first predetermined stroke, In the process when the internal pressure of the fuel tank decreases by a predetermined value or more, or in the previous process, the valve movable part is closed in the valve closing direction by the second predetermined stroke. An evaporative fuel processing apparatus characterized in that a valve opening start position is determined based on a stroke amount when the pressure changes. An evaporative fuel processing apparatus according to any one of claims 1 to 3,
The evaporative fuel processing apparatus is characterized in that learning of the valve opening start position of the blocking valve is performed every time an ignition switch of the engine is turned on.

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