JP5522399B2 - Leakage detection device for fuel evaporation gas processing equipment - Google Patents

Description

  The present invention relates to a leak detection device that detects a leak (leakage) occurring in a fuel evaporation gas processing device that introduces fuel evaporation gas in a fuel tank into an intake system of an engine.

  Since the fuel vaporized gas generated in the fuel tank causes air pollution, a vehicle equipped with an engine is generally equipped with a fuel vaporized gas treatment device for preventing discharge into the atmosphere. . The fuel evaporation gas processing device, for example, connects a fuel tank and an intake system of an engine with a purge line equipped with a canister, adsorbs the fuel evaporation gas generated in the fuel tank to activated carbon in the canister, The fuel vaporized gas in the activated carbon is introduced into the engine intake system according to the intake negative pressure and burned with fresh air.

  If a leak occurs in such a fuel vaporized gas processing apparatus due to some trouble, it directly leads to air pollution. Therefore, in the United States and the like, it is legally required to install an apparatus for detecting a leak. In particular, in accordance with US laws and regulations, such a leak detection device is provided as an OBD (On Board Diagnosis), and when a leak occurs, the driver can be notified by, for example, turning on a warning lamp. Mandatory.

  As a leak detection device, for example, the inside of the fuel tank is reduced to a predetermined pressure using the intake negative pressure of the engine while the vehicle is running, and then the gas introduction pipe that guides the fuel vaporized gas to the intake system is closed. There is a type in which the pressure inside the fuel tank is restored and the presence or absence of a leak is determined based on a change in the internal pressure of the fuel tank.

  As described above, in the method using the intake negative pressure while the vehicle is traveling, the pressure change in the tank caused by the fuel tank shake or the temperature change becomes a disturbance, and there is a possibility that the leak cannot be detected accurately. Therefore, a dedicated pump for depressurizing the inside of the canister is provided, for example, when the vehicle is parked, the inside of the canister is depressurized by this pump, and the leak of the fuel evaporation gas processing device is detected from the pressure change at that time. (For example, refer to Patent Document 1).

JP 2004-156492 A

  By providing the dedicated pump in this manner, for example, the leak detection of the fuel evaporation gas processing apparatus can be performed in a state where there is no disturbance such as when the vehicle is parked, so that the leak can be detected very accurately. However, if a dedicated pump is provided, there is a problem that the cost is greatly increased.

  This invention is made | formed in view of such a situation, and it aims at providing the leak detection apparatus of the fuel evaporation gas processing apparatus which can perform exact leak detection, suppressing an increase in cost.

A first aspect of the present invention that solves the above-described problem is a leak detection device for a fuel vaporized gas processing device that adsorbs vaporized fuel generated in a fuel tank mounted on a vehicle with a canister and processes the fuel. And one end is opened to the atmosphere so that a negative pressure is generated in the brake booster and the leak detection target area including the canister is blocked from the atmosphere. Is based on a negative pressure pump disposed in the open air passage connected to the canister, a pressure detection means for detecting the pressure in the area, and a negative pressure state in the area detected by the pressure detection means And a determination means for determining whether or not there is a leak in the region.

  In the first aspect, by using the negative pressure pump for the brake booster as the pressure generating means, it is not necessary to provide a dedicated pump. Therefore, it is possible to realize a leak detection device that can accurately detect the leak of the fuel evaporation gas processing device at a relatively low cost.

  According to a second aspect of the present invention, the negative pressure pump is connected to the brake booster by a negative pressure flow path, and the canister is connected by an intermediate flow path connected through a switching valve in the middle of the negative pressure flow path. And the intermediate flow path is provided with a flow rate control orifice for controlling the flow rate when the negative pressure pump is operated. The leak of the fuel vaporized gas processing apparatus according to the first aspect, In the detection device.

  In the second aspect, the flow rate by the negative pressure pump for the brake booster can be set to a more appropriate value, and the inside of the region can be set to a negative pressure more favorably.

  According to a third aspect of the present invention, the fuel according to the second aspect is characterized in that the intermediate flow path is provided with a check valve for restricting the flow from the negative pressure pump side to the canister side. It is in the leak detection device of the transpiration gas processing device.

  In the third aspect, backflow in the intermediate flow path is prevented when the leak detection device is activated. Therefore, the leak of the fuel vaporized gas processing device can be detected better.

  As described above, in the leak detection device of the present invention, it is not necessary to provide a dedicated pump by using a negative pressure pump for a brake booster, so that accurate leak detection can be performed while reducing costs. . Since the negative pressure pump for the brake booster is used when the vehicle is running and is not used when the vehicle is parked, there is no problem even if the negative pressure pump for the brake booster is used as a leak detection device. Further, the capacity of the negative pressure pump for the brake booster is sufficient to generate the negative pressure required at the time of leak detection, and if the present invention is used, it is not necessary to separately provide a negative pressure pump for leak detection.

It is a figure which shows schematic structure of the leak detection apparatus which concerns on one Embodiment of this invention. It is a figure which shows schematic structure of the negative pressure module which concerns on one Embodiment of this invention. It is a flowchart explaining the leak detection method which concerns on one Embodiment of this invention. It is a figure explaining the flow of the air in a negative pressure module.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, a fuel evaporation gas processing device 20 including a leak detection device 10 according to the present embodiment is mounted on a vehicle such as an automobile. The fuel vaporized gas processing device 20 is for preventing the vaporized fuel (vapor) generated in the fuel tank 30 of the vehicle from being released into the atmosphere. The vaporized fuel from the fuel tank 30 is removed from the vapor passage 40. The vaporized fuel adsorbed in the canister 50 is discharged (purged) into the intake passage 71 of the engine 70 of the vehicle through the purge passage 60 under a predetermined condition. .

  Specifically, a purge solenoid 65 that is an opening / closing means for opening and closing the purge passage 60 is interposed in the purge passage 60. The canister 50 is connected to an air release path 80 whose one end is open to the atmosphere. A negative pressure pump module 100 that constitutes the leak detection device 10 and generates a negative pressure in the canister 50 or the like is connected in the middle of the atmosphere opening path 80.

  As shown in FIG. 2, the negative pressure pump module 100 includes a negative pressure pump 101 that generates a negative pressure in the canister 50 and the like, and a pressure sensor 102 that detects the pressure in the module, and is connected to the canister 50. A first flow path 103, a second flow path 104 communicating with the atmosphere, and a third flow path (intermediate flow path) 105 connected to the negative pressure pump 101. A flow rate control orifice 106 for controlling the flow rate is provided in the middle of the third flow path 105. The second flow path 104 and the third flow path 105 are connected to the first flow path 103 via the first switching valve 107. That is, by switching the first switching valve 107, the first flow path 103 and the second flow path 104 or the third flow path 105 are connected to each other.

  Further, the negative pressure pump module 100 includes a bypass flow path 108 that connects the first flow path 103 and the third flow path 105 across the first switching valve 107. In the middle of the bypass channel 108, for example, a reference orifice 109 having a diameter of 0.5 mm is provided, and the pressure sensor 102 is provided closer to the second channel 104 than the reference orifice 109.

  In the negative pressure pump module 100 constituting the leak detection apparatus 10 according to the present invention, the negative pressure pump 101 uses a brake booster negative pressure pump (vacuum pump) constituting the brake device 200.

  Here, the vehicle brake device 200 will be briefly described. As shown in FIG. 1, the brake pedal 201 constituting the brake device 200 is supported on the vehicle body side so as to be rotatable around a fulcrum portion 202. At one end (lower end) of the brake pedal 201, an operation unit 203 that performs a stepping operation is provided. An operating rod 205 connected to the brake booster 204 is pivotally supported at the other end of the brake pedal 201. A master cylinder 206 is connected to the brake booster 204. A brake booster negative pressure pump 207 is connected to the brake booster 204, and a negative pressure is applied by the negative pressure pump 207. In such a brake device 200, the operating rod 205 is moved by depressing the operation unit 203 of the brake pedal 201, and the master cylinder 206 is operated via the brake booster 204. At that time, the brake booster 204 boosts the stepping operation force to actuate the master cylinder 206, so that the braking ability can be secured with a small stepping operation force of the brake pedal 201.

  And in the negative pressure pump module 100, the negative pressure pump 207 for brake boosters which comprises the brake device 200 is utilized as the negative pressure pump 101 as mentioned above. That is, as shown in FIG. 2, the negative pressure pump 207 (101) is connected to the brake booster 204 via the negative pressure channel 208. A check valve 209 is provided in the negative pressure channel 208. Then, the third flow path 105 is connected to the negative pressure flow path 208 via the second switching valve 110. That is, the negative pressure pump 101 (207) is connected to either the brake booster 204 or the canister 50 by switching the second switching valve 110 at a predetermined timing.

  Further, the negative pressure pump 101, the first switching valve 107 and the second switching valve 110, and the purge solenoid 65 provided in the purge passage 60 constituting such a negative pressure pump module 100 are controlled by a control signal from the ECU 150. Is controlled based on.

  In the leak detection device 10 of the present invention mounted on such a fuel vaporized gas processing device 20, a negative pressure pump module 100 causes a negative pressure within a predetermined region of the fuel vaporized gas processing device 20 with the purge solenoid 65 closed. Pressure is generated, and the presence or absence of leak is determined (detected) based on the pressure change at that time (determination means). When it is determined that there is a leak, for example, a warning lamp 15 for displaying a leak provided in the driver's seat is turned on to warn the driver.

  Hereinafter, the leak detection method by the leak detection apparatus 10 according to the present embodiment will be described with reference to the flowchart of FIG.

  Since the leak detection device 10 according to the present invention uses the negative pressure pump 207 (101) constituting the brake device 200 as described above, the leak detection device 10 performs leak detection when the vehicle is parked without affecting the operation. . That is, the negative pressure pump 207 (101) functions as the brake device 200 when the vehicle travels, and functions as the leak detection device 10 when the vehicle stops. By performing leak detection when the vehicle is parked, the influence of various disturbances can be suppressed as much as possible, so that the accuracy of leak detection is improved.

  As shown in FIG. 3, when the ignition switch of the vehicle is ON in step S1, that is, when the vehicle is capable of running or is running (step S1: Yes), the ECU 150 performs the second switching. The negative pressure pump 101 (207) is connected to the brake booster 204 by controlling the valve 110. Then, ON / OFF of the negative pressure pump 207 (101) is controlled so that the pressure in the brake booster 204 is always within a predetermined range.

  Specifically, first, when the ignition switch is turned on in step S1, it is determined in step S2 whether or not the pressure P2 in the brake booster 204 is equal to or higher than a first value (lower limit value). Note that the pressure in the brake booster 204 is constantly detected by a pressure sensor (not shown). If the pressure P2 in the brake booster 204 is equal to or higher than the first value (step S2: Yes), the negative pressure pump 207 (101) is switched from the OFF state to the ON state in step S3. As a result, the pressure P2 in the brake booster 204 gradually decreases.

  Thereafter, returning to step S1, if the ON state of the ignition switch is maintained, it is again determined in step S2 whether or not the pressure P2 in the brake booster 204 is equal to or higher than the first value. If the pressure P2 is still greater than or equal to the first value (step S2: Yes), the ON state of the negative pressure pump 207 (101) is maintained (step S3).

  On the other hand, when the pressure P2 in the brake booster 204 becomes lower than the first value (step S2: No), the negative pressure pump 207 (101) is switched from the ON state to the OFF state (step S4). Thereafter, in step S5, it is determined whether or not the pressure P2 in the brake booster 204 is equal to or higher than a second value (upper limit value) larger than the first value. When the pressure P2 is smaller than the second value (step S5: No), the process returns to step S4 and the OFF state of the negative pressure pump 207 (101) is maintained. When the pressure P2 becomes equal to or higher than the second value (step S5: Yes), the process proceeds to step S3, and the negative pressure pump 207 (101) is switched to the ON state again.

  Thus, when the ignition switch of the vehicle is in the ON state, ON / OFF of the negative pressure pump 207 (101) is appropriately controlled according to the pressure P2 in the brake booster 204, and the pressure P2 in the brake booster 204 is Is always held within a predetermined range (between the first value and the second value). Thereby, the braking capability of the brake device 200 during traveling of the vehicle can be ensured satisfactorily.

  Returning to step S1 again, if the ignition switch is in the OFF state (step S1: No), the leakage detection (leak check) of the fuel vaporized gas processing device by the leak detection device 10 is performed when the predetermined condition is satisfied. Executed.

  Specifically, it is first determined in step S6 whether or not a leak check flag is ON. For example, the leak check flag is set to ON when a predetermined period elapses from the previous leak check, and is set to OFF when the leak check is completed. If the leak check flag is ON (step S6: Yes), the process proceeds to step S7. If the leak check flag is OFF, the process ends. In step S7, it is determined whether or not a predetermined time has elapsed since the ignition switch was turned off. When the predetermined time has elapsed (step S7: Yes), the process proceeds to step S8. That is, when a predetermined time elapses after the ignition switch is turned off (step S7: Yes), it is determined that the predetermined condition for starting the leak check is satisfied, and the leak check is executed in steps after step S8. The elapsed time after the ignition switch is turned off is measured by, for example, a timer provided in the ECU 150.

  In step S8, the second switching valve 110 is switched from the negative pressure channel 208 side to the third channel 105 side. That is, the negative pressure pump 101 (207) is connected to the third flow path 105 via the second switching valve 110. Next, in step S9, the first switching valve 107 is switched as necessary, and the first flow path 103 and the second flow path 104 are connected. Next, in step S10, the negative pressure pump 101 (207) is turned on. In this state, as shown in FIG. 4A, air flows from the atmosphere side into the second flow path 104, the first flow path 103, and the bypass flow path 108, passes through the reference orifice 109, and has a negative pressure. It is discharged to the atmosphere side by the pump 101 (207).

  Next, in step S11, when a predetermined time has elapsed since the negative pressure pump 101 was turned on, the determination unit of the ECU 150 records the value α of the pressure sensor 102. This value α is a reference value for determining whether or not a leak has occurred.

  Next, in step S12, the first switching valve 107 is switched from the second flow path 104 side to the third flow path 105 side, and the first flow path 103 and the third flow path 105 are connected. In this state, as shown in FIG. 4B, air (gas) flows into the first flow path 103 and the third flow path 105 from the canister 50 side, and the atmospheric pressure is generated by the negative pressure pump 101 (207). Discharged to the side. As a result, the leak detection target region of the fuel vaporized gas processing apparatus 20 including the canister 50 is depressurized to a negative pressure. In the present embodiment, when the leak check is performed, the purge solenoid 65 is closed, so that a predetermined region (leak detection target region) on the fuel tank 30 side from the purge solenoid 65 is blocked from the atmosphere. This region is depressurized to a negative pressure. In the present embodiment, the flow rate by the negative pressure pump 101 (207) is appropriately controlled by the flow rate control orifice 106 provided in the third flow path 105.

  Next, in step S13, when a predetermined time has elapsed since the first switching valve 107 was switched in step S12 and the negative pressure pump 101 was turned on, the determination unit of the ECU 150 determines the value β of the pressure sensor 102 as the leak. Record as the pressure value in the detection area. Thereafter, the negative pressure pump 101 (207) is turned off (step S14).

  Next, in step S15, the determination unit of the ECU 150 compares the recorded reference value α with the pressure value β of the leak detection target region. If the pressure value β is equal to or greater than the reference value α (step S15). : No), it is determined that there is a leak, and a warning lamp (check lamp) is turned on (step S16). Thereafter, in step S17, the second switching valve 110 is switched from the third flow path 105 side to the negative pressure flow path 208 side, and the series of processes is completed. On the other hand, if the pressure value β is smaller than the reference value α in step S15 (step S15: Yes), the determination unit determines that there is no leak, and proceeds to step S17 without turning on the warning lamp, and a series of processes Exit.

  Thus, in the leak detection apparatus 10 of the fuel vaporized gas processing apparatus 20 according to the present invention, the fuel vaporized gas processing apparatus 20 is decompressed to a negative pressure by the negative pressure pump 101, and the leak is caused by the pressure at that time (negative pressure state). Whether or not there is is determined. Accordingly, since the leak detection of the fuel vaporized gas processing apparatus can be performed in a state where there is very little disturbance such as when the vehicle is parked, the presence or absence of the leak can be accurately detected. Furthermore, the leak detection apparatus 10 according to the present invention uses the negative pressure pump 207 (101) for the brake booster connected to the brake booster 204 that constitutes the brake apparatus 200 without using a dedicated negative pressure pump. did. Therefore, the cost can be greatly reduced, and the leak detection device 10 that can accurately determine the presence or absence of a leak can be realized at a relatively low cost.

  As mentioned above, although one embodiment of the present invention was described, of course, the present invention is not limited to this embodiment. For example, the third flow path (intermediate flow path) 105 may be provided with a check valve that restricts the flow from the negative pressure pump 101 (207) side to the canister 50 side. Thereby, at the time of a leak check, the backflow in the 3rd flow path 105 is prevented, and the leak of the fuel evaporation gas processing apparatus 20 can be detected more correctly.

  Further, for example, in the above-described embodiment, the presence / absence of leakage is determined by comparing the magnitude of the reference value α and the pressure value β, but the determination method of the presence / absence of leakage is not particularly limited. Absent. For example, a predetermined region in the fuel vaporized gas processing apparatus 20 may be set to a negative pressure by the negative pressure pump 101 (207), and the presence or absence of a leak may be determined based on the degree of subsequent pressure change or the like. In any case, by using the negative pressure pump 207 (101) for the brake booster as the leak detection device 10, the cost can be greatly reduced, and the presence or absence of the leak can be accurately determined. it can.

DESCRIPTION OF SYMBOLS 10 Leak detection apparatus 15 Warning light 20 Fuel evaporative gas processing apparatus 30 Fuel tank 40 Vapor path 50 Canister 60 Purge path 65 Purge solenoid 70 Engine 71 Intake path 80 Atmospheric release path 100 Negative pressure pump module 101,207 Negative pressure pump 102 Pressure sensor DESCRIPTION OF SYMBOLS 103 1st flow path 104 2nd flow path 105 3rd flow path 106 Flow control orifice 107 1st switching valve 108 Bypass flow path 109 Reference | standard orifice 110 2nd switching valve 200 Brake apparatus 204 Brake booster 208 Negative pressure flow Road 209 Check valve

Claims (3)

A leak detection device for a fuel evaporation gas processing device that absorbs and processes a vaporized fuel generated in a fuel tank mounted on a vehicle with a canister,
Connected to the brake booster to generate a negative pressure in the brake booster and to release a negative pressure in the leak detection target area including the canister from the atmosphere, one end is opened to the atmosphere. A negative pressure pump disposed at the other end of the air opening passage connected to the canister ;
Pressure detecting means for detecting pressure in the region;
Determination means for determining the presence or absence of leakage in the area based on the negative pressure state in the area detected by the pressure detection means;
A leak detection apparatus for a fuel vaporized gas processing apparatus. The negative pressure pump is connected to the brake booster by a negative pressure channel, and is connected to the canister by an intermediate channel connected via a switching valve in the middle of the negative pressure channel,
The leak detection apparatus for a fuel vaporized gas processing apparatus according to claim 1, wherein the intermediate flow path is provided with a flow rate control orifice for controlling a flow rate when the negative pressure pump is operated.   The leak detection apparatus for a fuel vaporized gas processing apparatus according to claim 2, wherein the intermediate flow path is provided with a check valve for restricting a flow from the negative pressure pump side to the canister side. .

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