JP2001099017A - Canister closing solenoid valve and airtightness checking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To add function for checking airtightness of a fuel tank system to a canister closing solenoid valve which switches releasing and closure of a canister against atmosphere. SOLUTION: When a piston member 4 descends, repulsion is generated between the piston member 4 and a valve member 3 due to magnets 631, 632. The valve member 3 is lowered so as to close a canister port 21. When negative pressure in the canister port 21 is a specified value or higher, the valve closing state is kept under the negative pressure. A negative pressure chamber 202 is arranged for introducing the negative pressure from the canister port 21 and applying it to the piston member 4. Magnetic flux variation of the magnet 632 integrated with the piston member 4 is sensed by a coil 71 for driving the piston member 4, for the knowledge that the piston member 4 reacts upon the negative pressure rise in the canister port 21, and that the piston member 4 reacts upon increase of repulsion at the time of opening the valve member 3 under the reduction of the negative pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve for closing a canister and an airtightness checking device using the same.

[0002]

2. Description of the Related Art A canister system is widely used as a technique for suppressing the emission of fuel vapor from an engine. FIG.
Shows a configuration around an engine that employs a canister system, and communicates with a fuel tank 921 to communicate with a canister 922.
Is provided, so that the fuel vapor generated in the fuel tank 921 is adsorbed on the activated carbon in the canister 922. The adsorbed fuel vapor is supplied to a purge solenoid valve (PV) 91.
2 is opened and purged into the intake manifold 924 of the engine 923 by the intake negative pressure.

[0003] A canister 92 is provided in the fuel tank 921.
Since the fuel tank system 92a provided with 2 is a space where fuel vapor exists, high airtightness is required, and an airtightness check device 91 for checking whether there is a leak in the fuel tank system 92a is provided. Basically, the airtightness check is performed by providing a pressure difference between the inside and outside of the fuel tank system 92a by the purge, closing the PV 912 and the canister closing solenoid valve (CCV) 913, and connecting the fuel tank system 92a to the intake manifold 924 and the air flowing to the atmosphere. The measurement is performed by detecting a negative pressure of the fuel tank system 92 a by a pressure sensor 911 provided in the fuel tank 921, with the space to be measured closed off from the filter 925. The determination of the airtightness is performed using the fact that the speed of the negative pressure drop of the closed fuel tank system 92a differs depending on the degree of the leak.

FIG. 14 is a flowchart showing the control of each section of the apparatus executed by the ECU 914, and FIG. 15 is a time chart showing the operation of each section of the apparatus. In step S901, the PV 912 is closed. In step S902, the CCV 913 is fully closed, and the fuel tank system 92a is closed to increase the tank internal pressure, that is, the pressure of the fuel tank system 92a. In step S903, it is confirmed that the pressure in the tank is not negative,
The rise width ΔP ₁ of the tank internal pressure when the preset Δt has elapsed (step S904) is measured (step S90).
5).

Next, in step S906, the PV 912 is opened and the fuel tank system 92a is purged. When the tank internal pressure becomes lower than -20 mmHg (step S907), P
V912 is closed (step S908).

At this time, the fuel tank system 92a is closed under a negative pressure.

[0007] Then, after closure, again after Delta] t (step S909) to measure the rise [Delta] P ₂ of the tank internal pressure (step S910), ΔP ₂ -ΔP ₁ determines whether exceeds a predetermined value ( Step S911). This represents a net leak amount of the fuel tank system 92a excluding an increase in the tank internal pressure due to the generation of fuel vapor in the fuel tank 921. If the leak amount exceeds a predetermined value, an airtight abnormality is indicated by the indicator light 915. It is displayed (step S912), and if it is less than the predetermined value, normal is displayed (step S913). After the display, the PV 912 and the CCV 913 are returned to the initial state (step S914), and the airtight check ends.

In the airtightness checker disclosed in Japanese Patent Application Laid-Open No. 5-340316, another pipe is provided for communicating the canister with the atmosphere, and an orifice and an orifice closing valve are provided in the middle of the pipe to reduce the negative pressure of the fuel tank system. Is measured both when the orifice closing valve is open and when the orifice closing valve is closed, offsetting factors such as the remaining fuel in the fuel tank and variations in the pressure sensor, etc. Some of them have been able to detect accurately.

[0009]

By the way, in the case of in-vehicle components, a reduction in the number of components is demanded in order to reduce component costs and improve mountability in vehicles. Since an increase in piping may result in an increase in the number of leak sources, simplification of the configuration is particularly desired.

The present invention has been made in view of the above circumstances,
Firstly, it is an object of the present invention to provide a canister closing solenoid valve capable of simplifying the configuration of an airtightness check device. A second object of the present invention is to provide an airtightness check device capable of accurately checking the airtightness of a fuel tank system with a simple configuration.

[0011]

According to the present invention, a canister port communicating with a canister, an atmosphere port opened to the atmosphere, a valve member housed in a valve chamber and closing the canister port are provided. Valve member urging means for urging the valve member in the valve opening direction, a piston member provided opposite to the valve member and capable of being displaced in the opposite direction, and urging the piston member in a direction approaching the valve member A piston member urging means, a negative pressure chamber in which negative pressure is introduced from the canister port and urges the piston member in a direction away from the valve member by the negative pressure; and Repulsive force generating means for generating a repulsive force in between,
Electromagnetic drive means for driving the piston member so as to be switchable between a direction electromagnetically approaching the valve member and a direction away from the valve member by a magnetic field generated by a coil; and a displacement movement for detecting a displacement movement of the piston member. A canister closing solenoid valve is provided with the detecting means.

After the piston member is brought closer to the valve member by the electromagnetic drive means and the valve member is closed by the repulsive force of the repulsive force generating means, the valve member is kept closed by the negative pressure of the canister port. When the negative pressure of the canister port rises, the piston member moves when the negative pressure chamber communicating with the canister port reaches a predetermined negative pressure, and the displacement motion detecting means detects that the fuel tank system has reached the predetermined negative pressure by purging. You can know. On the other hand, when the negative pressure of the canister port falls below another predetermined negative pressure lower than the predetermined negative pressure, the urging force of the valve member in the valve closing direction is reduced, the valve cannot be maintained in the closed state, and the valve opens and the piston member opens. Displaced toward. At this time, the piston member is displaced by the repulsive force of the repulsive force generating means, and it is possible to know that the fuel tank system has reached another predetermined negative pressure due to the leak by the displacement motion detecting means.

Thus, it is possible to know the degree of leakage of the fuel tank system without providing a separate pressure sensor.

According to a second aspect of the present invention, in the configuration of the first aspect of the present invention, a magnet is provided integrally with the piston member, and the displacement movement detecting means is formed by the magnet, and a coil of the electromagnetic driving means is provided. When the magnetic flux passing through the coil changes due to the displacement movement of the piston member, an electromotive force generated in the coil is detected.

By using the coil of the electromagnetic drive means as the coil for detecting the displacement movement of the piston member, the configuration of the canister closing electromagnetic valve itself can be simplified, and a cable for energizing the coil and a piston The cable can also be used as a cable for transmitting a current detection signal accompanying the displacement movement of the member.

According to a third aspect of the present invention, in the configuration of the first or second aspect, the repulsive force generating means is provided integrally with the magnet provided integrally with the piston member and the valve member. The magnet and the magnet have the same polarity and are opposed to each other.

Since the repulsive force between the valve member and the piston member can be obtained in a non-contact manner, manufacturing is easy. Further, the magnet on the piston member side can also be used as a magnet in a case where the displacement of the piston member is detected from the magnetic flux formed by the magnet (claim 2).

According to a fourth aspect of the present invention, a purge solenoid valve is provided in the middle of a purge flow path for connecting a fuel tank system to an intake pipe of an engine, and an atmosphere open flow path for opening the fuel tank system to the atmosphere. Claims 1 to 3 in the middle of
Either of the above-described solenoid valves for closing the canister is provided, and
Controlling means for energizing the purge solenoid valve and the canister closing solenoid valve for driving and determining airtightness of the fuel tank system based on a detection signal input from the displacement movement detecting means, to check for airtightness. Configure the device. And, after closing the piston member of the canister closing solenoid valve, the control means opens the purge solenoid valve to purge the fuel tank system,
When the displacement motion detecting means detects the displacement motion of the piston member which is recognized that the negative pressure of the negative pressure chamber has reached a predetermined leak check start pressure, the purge solenoid valve is closed, and the leak check is started. Within a predetermined time from the time when it is recognized that the pressure has reached the pressure, the displacement motion of the piston member, which is recognized as the negative pressure of the fuel tank system has reached the reference pressure after the predetermined leak, is detected by the displacement motion detecting means. The airtightness of the fuel tank system is determined based on whether or not the airtightness of the fuel tank system is high.

By employing the configuration according to any one of claims 1 to 3 for the canister closing solenoid valve, a pressure sensor is not required and the number of leak sources can be reduced.

According to a fifth aspect of the present invention, in the configuration of the fourth aspect of the present invention, there is provided a leak passage which has a throttle portion in the middle and connects the fuel tank system to the atmosphere side. Is provided with a throttle opening / closing solenoid valve for opening / closing the throttle section. Further, the control means is configured to control the energization for driving the throttle opening / closing solenoid valve, and to adjust the leak check start pressure in one of an open state and a closed state of the throttle section. The elapsed time from when it is recognized to have reached the reference pressure after the leak is measured and the elapsed time is set to the predetermined time, and in the other state of the open state and the closed state of the throttle,
Within the predetermined time from the point in time when it is recognized that the leak check start pressure has been reached, the displacement of the piston member, in which the negative pressure of the fuel tank system is recognized to have reached the predetermined post-leakage reference pressure, by the displacement motion detection means. The airtightness of the fuel tank system is determined based on whether motion is detected.

Since the behavior of the negative pressure in the fuel tank system can be compared between when the throttle portion whose degree of leak is known is opened and when the throttle portion is closed, the fuel remaining amount of the fuel tank and the manufacturing variation of each part of the device can be compared. Even if there is, etc., an accurate airtight check can be performed.

[0022]

(First Embodiment) FIG. 5 shows the configuration of an airtightness checking device according to a first embodiment of the present invention. In the fuel tank system 8a, a canister 82 is attached to a fuel tank 81, and the fuel tank 81 and the canister 82 communicate with each other through a canister communication pipe 801 so that the fuel vapor generated in the fuel tank 81 can be collected in the canister 82. The fuel tank 81 supplies fuel to an intake manifold 84 of the engine through a fuel pump and an injector (not shown). The canister 82 communicates with an air filter (which can be regarded as substantially atmospheric pressure) 86 through an atmosphere communication pipe 802, and a canister closing solenoid valve (C) is connected to the atmosphere communication pipe 802.
CV) 11. The canister 82 communicates with the intake manifold 84 downstream of the throttle valve 85 through a purge pipe 803, and the purge pipe 803 is a purge electromagnetic valve for purging fuel from the fuel tank system 8 a to the intake manifold 84. (PV) 1
2 is provided.

The energization control of CCV11 and PV12 is E
This is performed by the CU 13, and the ECU 13 may be configured to include a general microcomputer or the like. ECU1
Numeral 3 is provided with a detection circuit for detecting a current flowing through the power supply cable of the CCV 11, and determines whether the airtightness of the fuel tank system 8a is normal or abnormal based on the detected current as described later.

FIGS. 1 and 2 show the detailed configuration of the CCV 11. FIG. The CCV 11 includes a valve body 111 and a driving unit 112. The valve body 111 will be described. Housing 2 common to valve body 111 and drive 112
Has a substantially circular space formed therein, and has sleeve-shaped protrusions 21 and 22 on the bottom wall and the side wall of the housing 2.
Are provided as a canister port 21 communicating with the canister 82 and an atmosphere port 22 communicating with the air filter 86.

The interior of the housing 2 is provided with an atmosphere port 22 by a piston member 4 and a diaphragm 5 described later.
The first room on the lower side, which is a valve chamber, can communicate with the canister port 21 and the atmosphere port 22, and the upper second room 22, which is a negative pressure chamber, is Negative pressure introducing passage 203 formed in the wall of housing 2
Through the canister port 21.

The canister port 21 on the bottom wall of the housing 2
The opening peripheral portion 211 protrudes from the bottom surface of the first room 201, and a plurality of guide pins 23 are erected on the outer periphery thereof. Above the canister port opening peripheral portion 211, a flat circular valve member 3 is disposed, and is guided by a guide pin 23 so as to be vertically movable.

The valve member 3 is formed by molding a disk-shaped magnet 631 into a circular shape having a larger diameter than the canister port opening peripheral portion 211 by resin molding.
1 can be closed. A rubber sheet 31 is adhered to the lower surface of the valve member 3 and is in close contact with the canister port opening peripheral portion 211 when the valve member 3 is closed, thereby improving airtightness.

A first spring 61 as a valve member urging means is interposed between the valve member 3 and the bottom surface of the first room 201 to urge the valve member 3 upward, that is, in the valve opening direction. .

The driving section 112 will be described. Drive unit 1
Basically, the piston member 4 is electromagnetically driven using the piston member 4 as a moving core. A vertical hole 204 is formed in the ceiling wall of the second room 202 at a position directly above the valve member 3 in the vertical direction. 4 is slidably held. The piston member 4 is a columnar member formed by resin-molding the second magnet 632. A diaphragm 5 made of a rubber film is provided on an outer periphery of a lower end portion of the piston member 4, an outer peripheral edge of the diaphragm 5 is engaged with a side wall of the housing 2, and an inner peripheral edge is a flange protruding from the peripheral surface of the piston member 4. It is engaged with the part 41.

When the negative pressure of the canister port 21 is introduced into the second room 202 during purging of the fuel tank system 8a (FIG. 5), the first room 202 is replaced with the first room 201 which is always open to the atmosphere. Urges the piston member 4 upward through the diaphragm 5.

In the vertical hole 204, a stator core 72 is press-fitted and fixed above the piston member 4 to close the upper end opening of the vertical hole 204, and concave portions 401, 72 formed on the opposing surfaces of the stator core 72 and the piston member 4, respectively.
The second spring 62 is interposed in a compressed state during 01, and urges the piston member 4 downward.

A coil 71 is wound around the outer periphery of the vertical hole 204 so that power can be supplied from a terminal 75 of a connector portion provided at an upper portion of the housing 2. Also, the coil 71
, A yoke 73 and a magnetic plate 74 are provided.
1. The yoke 73 and the magnetic plate 74 form a magnetic circuit to attract or repel the second magnet 632 of the piston member 4 to drive the piston member 4 vertically. The driving direction of the piston member 4 can be switched upward or downward in the direction in which the coil 71 is energized. The upper end position of the displacement of the piston member 4 is defined by the position where the flange 41 projecting from the peripheral surface of the piston member 4 comes into contact with the ceiling surface of the second room 202. The stator core 72 is positioned so that a gap is formed between the stator core 72 and the stator core 72. This is to prevent the piston member 4 and the stator core 72 from colliding with each other when the piston member 4 is driven upward and from being broken.

The first magnet 631 of the valve member 3 and the second magnet 632 of the piston member 4 are oriented so that the same pole (N pole in the illustrated example) faces each other. Constitutes the repulsive force generating means 63, and a repulsive force acts between the valve member 3 and the piston member 4.

Next, the airtightness check device 1 and the CCV 11
The operation of will be described. First, the operation of the CCV 11 will be described. 3 and 4 show the operation states of the CCV in chronological order. The CCV 11 is closed prior to purging the fuel tank system 8a. In the initial state, the piston member 4 is in the upper position, and the second magnet 632 and the stator core 7
The downward displacement is prohibited by the magnetic force between the two. The valve member 3 is at an upper position by the upward biasing force of the first spring 631, and is open (FIG. 3A).

Next, the coil 71 is energized to cause a repulsive force to act on the second magnet 632 of the piston member 4 to lower the piston member 4. As the piston member 4 descends, the valve member 3 also descends due to the repulsive force of both magnets 631 and 632, and closes. (FIG. 3 (B)).

When purging of the fuel tank system 8a is started in this state, the fuel tank system 8a has a negative pressure, and therefore the canister port 21 has a negative pressure. On the other hand, the atmosphere port 22 and the first room 201 communicating with the air filter 86 (FIG. 5) maintain substantially atmospheric pressure. Thus, the urging force of the valve member 3 in the valve closing direction becomes more dominant. Also,
Negative pressure is introduced into the second room 202 from the canister port 21 through the negative pressure introducing passage 203 (FIG. 3C).

Here, when the power supply to the coil 71 is stopped, the electromagnetic driving force is reduced, and the piston member 4 is slightly raised. Thereby, the urging force in the valve closing direction on the valve member 3 due to the repulsive force between the two magnets 631 and 632 is reduced,
Since the canister port 21 has a negative pressure, the valve member 3 maintains the closed state.

When the negative pressure in the second room 202 exceeds a predetermined value as the negative pressure in the second room 202 rises, the piston member 4 rises, but the second magnet 632 passing through the magnetic circuit described above.
Causes a change in magnetic flux, and an induced electromotive force is generated in the coil 71. From the behavior of the induced electromotive force, the fuel tank system 8a
Is known to have reached a predetermined value (leak check start pressure).

Here, when the valve 12 is closed to stop purging, the lifting of the piston member 4 is stopped (FIG. 3D).

After the PV12 is closed, the fuel tank system 8a is a closed space. After that, the negative pressure of the fuel tank system 8a, that is, the canister port 21 and the second room 202 due to natural leak or leak due to airtightness abnormality.
Is gradually reduced again, and the piston member 4 is lowered. On the other hand, in the valve member 3, the repulsive force between the magnets 631 and 632 due to the lowering of the piston member 4 increases, but the negative pressure of the canister port 21 decreases, so that the urging force of the valve member 3 in the valve closing direction as a whole decreases. (FIG. 4E).

When the negative pressure of the fuel tank system 8a falls below a value at which the repulsive force between the magnets 631 and 632 and the spring force of the first spring 61 are balanced, the urging force of the valve member 3 in the valve opening direction becomes dominant. As a result, the valve member 3 opens. As the valve member 3 rises, the piston member 3 is pushed up by the repulsive force between the two magnets 631, 632 (FIG. 4).
(F)). At this time, an induced electromotive force is generated in the coil 71 again. From this, it is known that the negative pressure of the fuel tank system 8a has returned to a predetermined value (the post-leakage reference pressure).

In order to open the valve member 3 before the negative pressure of the fuel tank system 8a returns to a predetermined value, the coil 71 is energized in a direction opposite to that when the valve is closed, and the piston member 4 is connected to the stator core. Attract toward 72. Thus, the valve member 3 is released from the repulsive force between the magnets 631 and 632 and opens (FIG. 4G).

As described above, by detecting the displacement movement of the piston member 4 based on the electromotive force generated in the coil 71, the negative pressure of the fuel tank system 8a has increased to the leak check start pressure at the time of purging, It can be known that the negative pressure of the fuel tank system 8a in the state has decreased to the reference pressure after the leak.

Since it is not necessary to separately provide a pressure sensor (see FIG. 13), the CCV 11 has a simple structure when used in an airtightness check device, and has a hole for mounting the pressure sensor in the fuel tank 81 or the like. Since there is no need, the number of leak sources can be reduced.

Further, since the coil for generating the electromagnetic force for opening and closing the valve member is used as the displacement movement detecting means for detecting the displacement movement of the piston member, the configuration of the CCV itself can be simplified, and the power supply to the coil can be simplified. Other than the above, the current-carrying cable can also be used for detecting the coil current due to the induced electromotive force, so that the detection cable is unnecessary. Of course, the detection of the displacement motion of the piston member is not limited to the one in the present embodiment, but is separately provided by winding a detection coil over an energizing coil, and the like. May penetrate the detection coil, or a known sensor for detecting the displacement motion of the object may be provided.

The repulsive force between the piston member and the valve member is obtained by the magnetic force between the magnets provided on the piston member and the valve member. It is also possible to provide a repulsive force generating means by interposing a spring.

Next, the operation of the airtightness checking device will be described. FIG. 6 shows the control executed by the ECU 13, and FIG.
2 is a time chart showing the operating state of each part of the apparatus. In step S001, the coil 71 is energized to fully close the CCV 11 (the state shown in FIG. 3B).
V12 is opened to increase the negative pressure of the fuel tank system 8a, and in step S003, the energization of the coil 71 of the CCV 11 is stopped (the state of FIG. 3C).

In step S004, it is determined whether a predetermined change has occurred in the coil current. This determination is made based on, for example, whether or not the coil current has exceeded a predetermined threshold.

If there is no change in the coil current at which it is recognized that the piston member 4 has risen to the predetermined level, the process proceeds to step S004.
Is repeated. When it is determined that the coil current has undergone a predetermined change, it is determined that the negative pressure of the fuel tank system 8a has reached a predetermined leak check start pressure (the state shown in FIG. 3D), and the process proceeds to step S005. The PV 12 is closed. As a result, the fuel tank system 8a is closed by the CCV11 and PV12.

Thereafter, the elapsed time is counted by a built-in timer. At the start of counting, the negative pressure of the fuel tank system 8a is substantially a predetermined leak check start pressure. The speed of the negative pressure of the fuel tank system 8a differs depending on whether it is an allowable natural leak or an abnormal leak, but gradually decreases (the state of FIG. 4E). Then, when the counted elapsed time reaches a preset Δt (step S0)
06) and in step S007, it is determined whether or not there has been a change in the coil current value due to the opening of the valve member 3 during Δt. If leakage from the fuel tank system 8a is permissible, it takes time for the CCV 11 to reach the state shown in FIG. On the other hand, if the leakage of the fuel tank system 8a is abnormal, the negative pressure drops rapidly and the CCV
(F) is reached. Here, the maximum allowable leak is created in the fuel tank system 8a in advance, and the time from when the negative pressure of the fuel tank system 8a reaches the reference pressure after the leak to the reference pressure after the leak is determined. Is set to Δt, it can be determined that an abnormal leak has occurred when the predetermined current value changes before the elapse of Δt. The determination of the coil current is made based on, for example, whether the coil current has exceeded a predetermined threshold value.

If it is determined in step 007 that there has been a change in the current value, the flow advances to step S008 to turn on the indicator lamp 14 to indicate that an abnormality has occurred.
Proceed to. If it is determined in step 007 that there has been no change in the current value, the flow advances to step S009 to turn off the indicator lamp 14 to indicate that it is normal. In step S010, the coil 71 is energized in the reverse direction to fully open the CCV 11. (State of FIG. 4 (G)), and the process proceeds to Step S011.

Thus, the airtight check of the fuel tank system 8a is completed, and the CCV 11 and the PV 12 return to the initial state (step S011).

FIG. 8 shows a specific configuration of the airtightness checking device. Since the CCV 11 and PV 12 are integrally provided on the upper surface of the canister 82, the configuration of the device is compact, and piping connection and routing are easy. Becomes CC
The installation of V11 can be completed by fitting the canister port 21 into a through hole formed in the ceiling wall of the canister 82.

(Second Embodiment) FIG. 9 shows the configuration of an airtightness checking device according to a second embodiment of the present invention. In the figure, the first
Since the parts denoted by the same reference numerals as those of the embodiment perform substantially the same operation, the description will be focused on the differences. The canister 82 and the air communication pipe 802 are connected to the air filter 86 more than the CCV 11.
A leak pipe 15 which is a leak flow path connected on the side is provided. In the middle of the leak pipe 15, an orifice 16 which is a throttle portion and an orifice opening / closing solenoid valve 17 which is a throttle opening / closing solenoid valve are provided. ECU13A is CCV11,
The energization control of the orifice opening / closing solenoid valve 17 is performed together with the PV 12. The orifice 16 has its flow path cross-sectional area set to the maximum allowable cross-sectional area of the leak portion.

FIGS. 10 and 11 show a flowchart of the control in the ECU 13A, and FIG. 12 shows a time chart showing the operating state of each part of the apparatus.

In steps S101 to S105, similarly to the first embodiment, the coil 71 is energized to completely close the CCV 11 (step S101), and the PV 12 is opened to start purging the fuel tank system 8a (step S102). Then, the power supply to the coil 71 is stopped (step S103). Then, the purging is continued until the coil current value detected by the CCV 11 has a predetermined change (step S10).
4).

Next, in step S105, the PV 12 is closed, and in step S106, the orifice closing solenoid valve 17 is closed.
Is opened. Accordingly, if there is no leak source other than the orifice 16 in the fuel tank system 8a, the orifice 16
If the negative pressure of the fuel tank system 8a gradually decreases at a speed specified by the following equation, and there is a leak source other than the orifice 16 in the fuel tank system 8a, the fuel tank leaks through both the orifice 16 and the leak source and causes the fuel tank to leak. The vacuum in system 8a drops faster.

The time elapsed since the closing of the PV 12 valve and the opening of the orifice closing solenoid valve 17, that is, the elapsed time from the time when the fuel tank system 8 a reached the leak check start pressure is counted by a built-in timer, and the current value is calculated. It is determined whether or not there has been a change, that is, whether or not the negative pressure of the fuel tank system 8a has reached a predetermined post-leakage reference pressure (step S10).
7).

When it is determined that the negative pressure of the fuel tank system 8a has reached the reference pressure after a predetermined leak in the coil current value, the process proceeds to step S108, where the negative pressure of the fuel tank system 8a is reduced to a predetermined value. The elapsed time up to the point when the pressure reaches the reference pressure after the leakage is denoted by Δt, and the CCV is determined in step S109.
11, the PV 12 and the orifice closing solenoid valve 17 are returned to the initial state. Therefore, the orifice closing solenoid valve 17 returns to the closed state. Further, the fuel tank system 8a returns to the atmospheric pressure again.

Again, the coil 71 is energized to completely close the CCV 11 (step S110), the PV 12 is opened to purge the fuel tank system 8a (step S111), and the energization of the coil 71 is stopped (step S112). . Then, purging is continued until there is a predetermined change in the coil current value detected by the CCV 11 (step S11).
3).

Next, the PV 12 is closed and the fuel tank system 8 is closed.
a is closed (step S114).

As in the case of opening the orifice opening / closing solenoid valve 17, the time elapsed from the point when the fuel tank system 8a reaches the leak check start pressure is counted by a built-in timer, and 2 × Δt elapses (step). S115), and in step S116, it is determined whether or not the current value has changed during 2 × Δt.

Now, the measurement of Δt (step S10)
In 8), the negative pressure drop of the fuel tank system 8a is caused by the leak of the orifice 16 and the fuel tank system 8a. The fact that only the leak of the fuel tank system 8a takes 2 × Δt means that the leak of the fuel tank system 8a Is the orifice 1
6 is almost equal to the leak. Thus, 2 × Δt
If there is no change in the current value within the range, it can be determined that the leakage of the fuel tank system 8a is permissible. If there is a change in the current value within 2 × Δt, the leakage of the fuel tank system 8a is within the allowable upper limit. It can exceed it and can be judged as abnormal.

If it is determined in step 116 that there has been a change in the current value, the flow advances to step S117 to turn on the display lamp 14 to indicate that an abnormality has occurred, and the flow advances to step S120. If it is determined in step S116 that there has been no change in the current value, the flow advances to step S118 to indicate that the indicator lamp 14 is not lit, indicating that it is normal, and in step S119, the coil 71 is energized in the reverse direction to perform CCV.
11 is fully opened, and the process proceeds to step S120.

Thus, the airtightness check of the fuel tank system 8a is completed, and the CCV 11, PV 12, and the orifice closing solenoid valve 17 return to the initial state (step S120).

In the present embodiment, the orifice 16 is set to be the same as the largest allowable leak. However, the present invention is not limited to this. If the orifice 16 is closed, the change in coil current value The time for determining the presence or absence (step S115) may be adjusted. Also,
The measurement of the elapsed time (step S108) is performed using the orifice 16
While the orifice 16 is closed, the elapsed time Δt is measured with the orifice 16 closed, and then the orifice 1
A configuration may be adopted in which the fuel tank system 8a is lowered from the leak check start pressure in a state in which the coil current value is opened, and whether or not the coil current value changes during Δt / 2.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a canister closing solenoid valve of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIGS. 3 (A), (B), (C), and (D) are schematic diagrams showing the operation states of the canister closing solenoid valve in a time series.

FIGS. 4 (E), (F), and (G) are schematic diagrams in which the operation states of the canister closing solenoid valve are time-series.

FIG. 5 is a configuration diagram around an engine showing an airtightness checking device of the present invention.

FIG. 6 is a flowchart showing control executed by an ECU of the airtightness checking device.

FIG. 7 is a time chart showing an operation state of each part of the airtightness check device.

FIG. 8 is a specific configuration diagram around an engine showing the airtightness checking device.

FIG. 9 is a configuration diagram around an engine showing another airtightness check device of the present invention.

FIG. 10 is a first flowchart showing control executed by an ECU of the airtightness checking device.

FIG. 11 is a second flowchart showing control executed by an ECU of the airtightness checking device.

FIG. 12 is a time chart showing an operation state of each part of the airtightness checking device.

FIG. 13 is a configuration diagram around an engine showing a typical example of a conventional airtightness checking device.

FIG. 14 is a flowchart showing control executed by an ECU of the airtightness checking device.

FIG. 15 is a time chart showing an operation state of each part of the airtightness check device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air-tightness check device 11 Solenoid valve for closing a canister 2 Housing 21 Canister port 22 Atmospheric port 201 First room (valve chamber) 202 Second room (negative pressure chamber) 203 Negative pressure introduction flow path 3 Valve member 4 Piston member 5 Diaphragm 61 First spring (valve member urging means) 62 Second spring (piston member urging means) 63 Repulsive force generating means 631 First magnet (magnet) 632 Second magnet (magnet) 7 Electromagnetic drive means 71 Coil 12 Purge electromagnetic Valve 13 ECU (control means) 15 Leak pipe (leak flow path) 16 Orifice (throttle section) 17 Orifice opening / closing solenoid valve (throttle opening / closing solenoid valve) 8a Fuel tank system 802 Atmosphere communication pipe (atmosphere communication flow path) 803 Purge tube

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 37/00 301 F02M 37/00 301G

Claims (5)

[Claims] An electromagnetic valve for closing a canister, which is provided in the middle of an open air passage for opening a canister for temporarily holding fuel vapor generated in a fuel tank to the atmosphere and switches between closing the canister and opening the atmosphere, A canister port communicating with the canister, an atmosphere port opened to the atmosphere, a valve member housed in a valve chamber for closing the canister port, a valve member urging means for urging the valve member in a valve opening direction, A piston member provided opposed to the valve member and capable of being displaced in the opposite direction; a piston member urging means for urging the piston member in a direction approaching the valve member; and a negative pressure being introduced from the canister port. A negative pressure chamber for urging the piston member away from the valve member by the negative pressure generates a repulsive force between the valve member and the piston member. Repulsive force generating means, electromagnetic driving means for driving the piston member to be switchable between a direction electromagnetically approaching the valve member and a direction separating from the valve member electromagnetically by a magnetic field generated by a coil; and An electromagnetic valve for closing a canister, comprising: a displacement movement detecting means for detecting a displacement movement. 2. The electromagnetic valve for closing a canister according to claim 1, wherein a magnet is provided integrally with said piston member, and said displacement movement detecting means is formed by said magnet and passes through said coil of said electromagnetic driving means. A canister closing solenoid valve configured to detect an electromotive force generated in the coil when a generated magnetic flux changes due to a displacement movement of the piston member. 3. A solenoid valve for closing a canister according to claim 1, wherein said repulsive force generating means comprises a magnet provided integrally with said piston member and a magnet provided integrally with said valve member. An electromagnetic valve for closing a canister, which is configured and has the same polarity of both magnets facing each other. 4. An airtightness check device for checking the airtightness of a fuel tank system comprising a fuel tank and a canister for adsorbing fuel evaporated in the fuel tank, wherein the airtightness check device includes a fuel tank system and an intake pipe of an engine. An electromagnetic valve for purging is provided in the middle of a purge flow path to be communicated, and the electromagnetic valve for closing a canister according to any one of claims 1 to 3 is provided in an air open flow path for opening the fuel tank system to the atmosphere. Controlling means for energizing the solenoid valve for purging and the solenoid valve for closing the canister for driving and for determining airtightness of the fuel tank system based on a detection signal inputted from the displacement movement detecting means. After closing the piston member of the canister closing solenoid valve, the control means opens the purge solenoid valve to purge the fuel tank system. By the displacement motion detecting means,
When the displacement of the piston member is detected, in which the negative pressure in the negative pressure chamber has reached a predetermined leak check start pressure, the purge solenoid valve is closed, and it is recognized that the leak check start pressure has been reached. Based on whether or not the displacement motion of the piston member, which is recognized that the negative pressure of the fuel tank system has reached a reference pressure after a predetermined leak, is detected by the displacement motion detection means within a predetermined time from the time point. An airtightness check device, wherein airtightness of a fuel tank system is determined. 5. The airtightness check device according to claim 4, further comprising a leak portion having a throttle portion in the middle thereof for connecting the fuel tank system to the atmosphere side, and a throttle portion in the middle of the leak flow channel. A throttle opening / closing solenoid valve for opening / closing the throttle, and the control means is configured to control the energization for driving the throttle opening / closing solenoid valve. In one of the states, the elapsed time from when it is recognized that the leak check start pressure has been reached to when it reaches the post-leakage reference pressure is measured, and the elapsed time is set to the predetermined time, and the state in which the throttle section is opened. In the other of the closed state and the predetermined time from the point in time when it is recognized that the leak check start pressure has been reached, the displacement motion detecting means sets the negative pressure of the fuel tank system to the predetermined pressure. An airtightness check device configured to determine airtightness of the fuel tank system based on whether or not displacement movement of the piston member recognized as having reached a reference pressure after the leak is detected.