JP2018048873A - Leakage inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leakage inspection device capable of easily and appropriately inspecting the presence or absence of leakage from a container even when the inner capacity and the temperature of the container change.SOLUTION: A leakage inspection device 1 of an evaporation purge system 100 for purging a fuel evaporation gas inside a fuel tank 2 into an intake passage 10 of an internal combustion engine provides a reference vent hole φr between the inner part (container) of a fuel tank 2 and an atmosphere 200 and switches, by a first valve Va1, between a first state in which the communication between the inner part of the fuel tank 2 and the atmosphere 200 is blocked via the reference vent hole φr and a second state in which the inner part of the fuel tank 2 and the atmosphere 200 via the reference vent hole φr is communicated. Leakage determination means 92 determines the leakage of the fuel tank 2 including the fuel tank 2 on the basis of a comparison result with a temporal change of a pressure P in a first state after the pressure P inside the fuel tank 2 is changed to a pressure value different from the atmospheric pressure and the temporal change of the pressure P in a second state by a pump 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a leakage inspection device that detects leakage from a container such as a fuel tank.

  In order to prevent the fuel evaporative gas in the fuel tank (container) from being released into the atmosphere, the fuel evaporative gas in the fuel tank is adsorbed to the canister via the passage, and the adsorbed fuel evaporative gas is An evaporation purge system for purging an intake passage is known. As a leakage inspection method for such an evaporation purge system, the evaporation purge system including the fuel tank is sealed, and the presence or absence of leakage is diagnosed by comparing the pressure in the sealed space with a leakage determination threshold value. The method is known. At this time, if the fuel tank is deformed by the pressure difference between the inside and outside of the fuel tank, the internal volume of the fuel tank changes and affects the pressure in the evaporation purge system. Further, if the fuel evaporation amount in the fuel tank fluctuates due to the temperature of the fuel tank, the pressure in the evaporation purge system is affected. Therefore, it has been proposed to set a leak determination threshold value according to the deformation amount of the fuel tank and the environmental temperature (see cited document 1).

JP 2009-2193615 A

  However, since the volume and temperature of the fuel tank change with time, the method of changing the leak determination threshold in response to changes in the volume and temperature of the fuel tank is time consuming and error-prone. There is a problem that judgment is likely to occur.

  In view of the above problems, an object of the present invention is to provide a leak inspection device for an evaporation purge system that can easily and appropriately inspect for leakage from a container even when the internal volume or temperature of the container changes. It is to provide.

  In order to solve the above problems, a leak inspection apparatus according to the present invention includes a pressure detection means for detecting a pressure in a container to be inspected, a pump connected to the container, and between the atmosphere and the container. The reference vent hole interposed in the first state, the first state in which the communication between the container and the atmosphere through the reference vent hole is blocked, and the inside of the container and the atmosphere communicate with each other through the reference vent hole. Switching means for switching to the second state, time change of the pressure in the first state and time change of the pressure in the second state after the pressure is changed to a pressure value different from atmospheric pressure by the pump And a leakage determination means for determining leakage of the container based on the comparison result.

In the present invention, the reference vent hole is interposed between the atmosphere and the inside of the container, and the switching means has a first state in which communication between the inside of the container and the atmosphere through the reference vent hole is interrupted, and the reference It switches to the 2nd state which the inside of a container and air | atmosphere connected via the vent hole for use. For this reason, after the pressure in the container is changed to a pressure value different from the atmospheric pressure by the pump, the temporal change in the pressure in the container in the first state is detected by the pressure detection means, the switching means, and the leakage determination means, It is possible to determine the temporal change of the pressure in the container in the state. Further, by comparing such changes, it is possible to determine the leakage of the container, and it is difficult for the determination result to be affected by the internal volume of the container and the temperature. For this reason, even if there is a change in the internal volume of the container or a change in temperature, it is possible to determine the presence or absence of leakage without performing correction of the measurement result or correction of the threshold for determination of leakage, etc. Appropriate inspection can be easily performed.

  In the present invention, the leakage determination means may include a first time until the pressure changes from the first pressure value to the second pressure value in the first state and the pressure from the first pressure value in the second state. A mode having a calculation unit that calculates a ratio to the second time until the second pressure value is changed, and a comparison unit that determines the leak by comparing the ratio with a threshold for leak determination. Can be adopted.

  In the present invention, the pump can adopt a mode in which the inside of the container is depressurized.

  In the present invention, the container may be a fuel tank in which fuel evaporative gas is purged into an intake passage of an internal combustion engine.

    In the present invention, the reference vent hole is interposed between the atmosphere and the inside of the container, and the switching means has a first state in which communication between the inside of the container and the atmosphere through the reference vent hole is interrupted, and the reference It switches to the 2nd state which the inside of a container and air | atmosphere connected via the vent hole for use. For this reason, after the pressure in the container is changed to a pressure value different from the atmospheric pressure by the pump, the temporal change in the pressure in the container in the first state is detected by the pressure detection means, the switching means, and the leakage determination means, It is possible to determine the temporal change of the pressure in the container in the state. Further, by comparing such changes, it is possible to determine the leakage of the container, and it is difficult for the determination result to be affected by the internal volume of the container and the temperature. For this reason, even if there is a change in the internal volume of the container or a change in temperature, it is possible to determine the presence or absence of leakage without performing correction of the measurement result or correction of the threshold for determination of leakage, etc. Appropriate inspection can be easily performed.

It is explanatory drawing which shows the structure of the leak inspection apparatus of the evaporation purge system to which this invention is applied. It is a time chart which shows the operation | movement in the leak test | inspection apparatus shown in FIG. It is explanatory drawing which shows the result of having simulated the time change of the pressure in the leak test method which concerns on the reference example of this invention. It is explanatory drawing which shows the result of having simulated the time change of the pressure in the leak test method to which this invention is applied.

(Configuration of leak inspection apparatus 1)
FIG. 1 is an explanatory diagram showing a configuration of a leakage inspection apparatus of an evaporation purge system to which the present invention is applied. The evaporative purge system leakage inspection apparatus 1 shown in FIG. 1 includes an evaporative purge system 20 that includes a fuel tank 2 in an evaporative purge system 100 that purges fuel evaporative gas in a fuel tank 2 (container) into an intake passage 10 of an internal combustion engine. This is a device for diagnosing leakage of fuel evaporative gas.

  The leak inspection apparatus 1 includes a pressure gauge 3 as pressure detecting means for detecting the pressure in the fuel tank 2, a pump 4 connected to the fuel tank 2, and a reference interposed between the atmosphere 200 and the fuel tank 2. Air vent hole φr. The leakage inspection apparatus 1 has a first valve Va1 as switching means, and the first valve Va1 is a first valve that blocks communication between the fuel tank 2 and the atmosphere 200 through the reference vent hole φr. The state is switched to the second state in which the inside of the fuel tank 2 communicates with the atmosphere 200 through the reference vent hole φr.

  More specifically, the first flow path 21 connected to the fuel tank 2 is provided with a reference vent hole φr having a sonic conductance C2, and the first flow path 21 includes a reference vent hole φr and Between the fuel tank 2, a first valve Va1 is provided as switching means. In the second flow path 22 connected to the fuel tank 2, a canister 6, a second valve Va2, and a pump 4 are provided in this order from the fuel tank 2 to the atmosphere 200. In the second flow path 22, a pressure gauge 3 as a pressure detecting means is connected between the fuel tank 2 and the canister 6.

  One end of the third flow path 23 is connected between the canister 6 of the second flow path 22 and the second valve Va 2, and the other end of the third flow path 23 communicates with the atmosphere 200. The third flow path 23 is provided with a third valve Va3. In the second flow path 22, one end of the fourth flow path 24 is connected between the canister 6 and the pressure gauge 3, and the other end of the fourth flow path 24 communicates with the atmosphere 200. The fourth flow path 24 is provided with a fourth valve Va4. The second flow path 22 and the fourth flow path 24 constitute an evaporation purge system 100 that purges the fuel evaporative gas generated in the fuel tank 2 into the intake passage 10 of the internal combustion engine. The leakage inspection apparatus 1 inspects the leakage of fuel evaporative gas from the fuel tank 2 through the second flow path 22 and the fourth flow path 24 to the fourth valve Va4. In FIG. 1, the leakage of the fuel evaporative gas in the fuel tank 2 is represented as a virtual inspection object hole φx having a sonic conductance C1.

  The leakage inspection apparatus 1 configured as described above is provided with a control unit 9, and the control unit 9 performs switching control of the pump 4, the first valve Va 1, the second valve Va 2, and the third valve Va 3. 91 and leak determination means 92 for determining leakage of fuel evaporative gas based on the detection result of the pressure gauge 3. Further, the switching control unit 91 performs switching control of the fourth valve Va4. In this embodiment, the leak determination means 92 performs a calculation on the detection result of the pressure gauge 3 to calculate a pressure change time ratio, which will be described later, and the pressure change time ratio obtained by the calculation unit 921 as a leak determination. And a comparison unit 922 that determines leakage in comparison with the use threshold.

  Here, the control part 9 is comprised by the computer, and performs the leak test demonstrated with reference to FIG. 2 based on the leak test program previously stored in the memory | storage device (not shown).

(Operation for inspection)
FIG. 2 is a time chart showing the operation of the leak inspection apparatus 1 shown in FIG. In FIG. 2, in the period T0, the first valve Va1, the second valve Va2, and the third valve Va3 are closed, while the fourth valve Va4 is open. Therefore, the fuel evaporative gas generated in the fuel tank 2 can be purged to the intake passage 10 via the second flow path 22 and the fourth flow path 24. Meanwhile, the pump 4 is kept off. Further, the opening degree of the fourth valve Va4 is adjusted, and the speed at which the fuel evaporative gas is purged into the intake passage 10 is adjusted.

  Next, in the rest period Ts1, the first valve Va1, the second valve Va2, the third valve Va3, and the fourth valve Va4 are closed while the pump 4 is in an off state.

  Next, in the first preparation period Tr1 for inspection, the first valve Va1, the third valve Va3, and the fourth valve Va4 are closed, and the second valve Va2 is opened. Further, the pump 4 is turned on, and the fuel tank 2 is brought into a negative pressure state. In the detection result of the pressure gauge 3, the valve Va2 is closed when the pressure P of the fuel tank 2 reaches a predetermined pressure value Ps (measurement start pressure), and the first inspection period Td1 starts.

In the first inspection period Td1, since the first valve Va1, the second valve Va2, the third valve Va3, and the fourth valve Va4 are in the closed state, the inside of the fuel tank 2 and the atmosphere 200 through the reference vent hole φr. Is in the first state in which the communication is cut off. In this state, since the outside air enters the fuel tank 2 only due to leakage (inspection hole φx) in the fuel tank 2, the pressure P of the fuel tank 2 gradually increases. Then, a first time t1 until the pressure P of the fuel tank 2 reaches the threshold pressure Pt from the pressure value Ps (measurement start pressure) is obtained. Meanwhile, the pump 4 is turned off.

  After the first inspection period Td1, in the second preparation period Tr2, the first valve Va1, the third valve Va3, and the fourth valve Va4 are closed, and the second valve Va2 is opened. Further, the pump 4 is turned on, and the fuel tank 2 is again brought into a negative pressure state. As a result of detection by the pressure gauge 3, when the pressure P of the fuel tank 2 reaches a predetermined pressure value Ps (measurement start pressure), the second valve Va2 is closed and the first valve Va1 is opened. The second inspection period Td2 is started.

  In the second inspection period Td2, the second valve Va2, the third valve Va3, and the fourth valve Va4 are closed. However, since the first valve Va1 is open, the fuel tank 2 is connected via the reference vent hole φr. It is in the 2nd state which the inside and atmosphere 200 communicated. Therefore, outside air enters the fuel tank 2 due to leakage in the fuel tank 2 (inspection hole φx), and outside air also enters the fuel tank 2 from the reference vent hole φr, and the pressure P of the fuel tank 2 is increased. To rise. Then, the second time t2 until the pressure P of the fuel tank 2 reaches the threshold pressure Pt from the pressure value Ps (measurement start pressure) is obtained. Meanwhile, the pump 4 is turned off.

  After the second inspection period Td2, in the rest period Ts2, the third valve Va3 is opened in the middle while the pump 4 is kept off.

  In this way, the temporal change of the pressure P in the first inspection period Td1 and the second inspection period Td2 is measured, and the leakage determination unit 92 determines the leakage of the fuel tank 2 based on the measurement result. Thereafter, the first valve Va1, the second valve Va2, and the third valve Va3 are closed, and the fourth valve Va4 is opened.

  In the present embodiment, the calculation unit 921 of the leakage determination unit 92 causes the first time t1 until the pressure P changes from the first pressure value to the second pressure value in the first state, and the pressure P is the first in the second state. The ratio with the second time t2 until the pressure value changes to the second pressure value is calculated, and the comparison unit 922 of the leak determination unit 92 determines the ratio between the first time t1 and the second time t2 as a leak determination threshold value. Judge the leak as compared to.

More specifically, the calculation unit 921 obtains the pressure change time ratio R based on the following expression, and the comparison unit 922 compares the pressure change time ratio R with the leak determination threshold value.
Pressure change time ratio R = first time t1 / second time t2

  In such comparison, the comparison unit 922 determines that there is a leak when the pressure change time ratio R is greater than the leak determination threshold, and determines that there is no leak when the pressure change time ratio R is less than the leak determination threshold. .

(Main effects of this form)
As described above, in this embodiment, the reference vent hole φr is interposed between the atmosphere 200 and the inside of the fuel tank 2, and the first valve Va1 as the switching means is connected via the reference vent hole φr. The first state in which the communication between the inside of the fuel tank 2 and the atmosphere 200 is cut off, and the second state in which the inside of the fuel tank 2 and the atmosphere 200 are connected via the reference vent hole φr. For this reason, after the pressure in the fuel tank 2 is changed to a pressure value Ps (measurement start pressure) different from the atmospheric pressure by the pump 4, the pressure gauge 3 as the pressure detecting means, the first valve Va1 as the switching means, and the leakage The determination means 92 can determine a temporal change in the pressure in the fuel tank 2 in the first state and a temporal change in the pressure in the fuel tank 2 in the second state. Further, by comparing such changes, the leakage of the fuel tank 2 can be inspected, and the inspection results include the internal volume and temperature of the fuel tank 2 as will be described later with reference to FIGS. Impact is difficult to reach. For this reason, even if a change in the internal volume of the fuel tank 2 or a temperature change occurs, the presence or absence of leakage can be determined without correcting the measurement result or correcting the leak determination threshold value. There is an advantage that it is possible to easily perform an appropriate inspection for the presence or absence.

(Influence of internal volume and temperature of fuel tank 2)
FIG. 3 is an explanatory diagram illustrating a result of simulating a temporal change in pressure in the leakage inspection method according to the reference example of the present embodiment. FIG. 4 is an explanatory view showing the result of simulating the temporal change in pressure in the leak inspection method to which the present invention is applied, and shows the pressure change time ratio R under various conditions.

  In FIG. 3C, as a leakage inspection method according to a reference example of the present invention, as shown in FIG. 3A, the temporal change in pressure when the reference vent hole φr is not provided is shown by solid lines L1 to L4. The inner diameter of the inspection target hole φx is 0.5 mm. In FIG. 3 (c), a solid line L1 indicates a temporal change in pressure when the internal volume of the fuel tank 2 is 130 L (liter) and the temperature is + 25 ° C. A solid line L2 indicates a temporal change in pressure when the internal volume of the fuel tank 2 is 130L and the temperature is + 85 ° C. A solid line L3 indicates a temporal change in pressure when the internal volume of the fuel tank 2 is 130 L and the temperature is −30 ° C. A solid line L4 indicates a temporal change in pressure when the internal volume of the fuel tank 2 is 13L and the temperature is + 25 ° C. In FIG. 3 (c), as shown in FIG. 3 (b), the pressure in the case where the inspection target hole φx having an inner diameter of 0.5 mm and the reference vent hole φr having an inner diameter of 0.5 mm are provided. The change with time is indicated by a solid line L5. In this case, the internal volume of the fuel tank 2 is 130L and the temperature is + 25 ° C. FIG. 3 (c) shows a change from a pressure value Ps (measurement start pressure) of −4.5 kPa to a threshold pressure Pt of −2.5 kPa.

  FIG. 4 shows that in the leak inspection method according to the present embodiment, when the inner diameter of the inspection target hole φx is changed from 0.3 mm to 0.7 mm, the internal volume of the fuel tank 2 is 130 L (liter) and the temperature is +25. The pressure change time ratio R at ° C, the pressure change time ratio R when the internal volume of the fuel tank 2 is 130L and the temperature is + 85 ° C, and the pressure change time ratio R when the internal volume of the fuel tank 2 is 13L and the temperature is + 25 ° C. , Indicated by solid lines L11, L12, and L13. The inner diameter of the reference vent hole φr is 0.5 mm.

  As can be seen from the results indicated by the solid lines L1 to L4 in FIG. 3, when the internal volume or temperature of the fuel tank 2 changes, the temporal change in the pressure P in the fuel tank 2 changes greatly. Therefore, it is necessary to correct the threshold value in the case where the leakage is determined by the temporal change of the pressure P depending on the internal volume and temperature of the fuel tank 2.

  Further, as can be seen from the result shown by the solid line L5 in FIG. 3, when the reference vent hole φr is provided, the pressure P in the fuel tank 2 changes in a short time. However, as shown in FIG. 4, even if the internal volume and temperature of the fuel tank 2 change, the pressure change time ratio R used in the present embodiment hardly changes, and the size (leakage degree) of the inspection target hole φx changes. Even if it makes it, the pressure change time ratio R used by this form does not change easily. When the reference vent hole φr and the inspection target hole φx are equal in size, the pressure change time ratio R is 2.

[Other embodiments]
In the above embodiment, the inside of the fuel tank 2 is decompressed by the pump 4, but the inside of the fuel tank 2 may be pressurized by the pump 4. In the above embodiment, the reference vent hole φr is connected to the fuel tank 2. However, if the reference vent hole φr is interposed between the fuel tank 2 and the atmosphere 200, the reference vent hole φr is used. The air hole φr may be connected to the first flow path 21 or the second flow path 22. Further, in the above embodiment, the pressure change time ratio R calculated by the first time t1 / second time t2 is compared with the leak determination threshold, but the pressure change time calculated by the second time t2 / first time t1. A mode in which the ratio R is compared with the threshold value for leak determination or a mode in which a pressure change during a certain period of time is compared between the first state and the second state may be employed.

DESCRIPTION OF SYMBOLS 1 ... Leak inspection apparatus, 2 ... Fuel tank (container), 3 ... Pressure gauge (pressure detection means), 4 ... Pump, 6 ... Canister, 9 ... Control part, 10 ... Intake passage, 20 ... Evaporative purge system, 21 ... 1st 1 channel, 22 ... 2nd channel, 23 ... 3rd channel, 91 ... switching control part, 92 ... leak judging means, 100 ... evaporation purge system, 200 ... air | atmosphere, 921 ... calculating part, 922 ... comparison part, φr: reference vent hole, φx: inspection target hole, Va1: first valve (switching means), Va2: second valve, Va3: third valve, Td1: first inspection period, Td2: second inspection period, Ps ... Pressure value, Pt ... Threshold pressure

Claims (4)

Pressure detecting means for detecting the pressure in the container to be inspected;
A pump connected to the container;
A reference vent hole interposed between the atmosphere and the inside of the container;
A switching means for switching to a first state in which communication between the container and the atmosphere through the reference vent hole is blocked, and a second state in which the inside of the container and the atmosphere communicate through the reference vent hole;
The container based on a comparison result between a temporal change of the pressure in the first state and a temporal change of the pressure in the second state after the pressure is changed to a pressure value different from the atmospheric pressure by the pump. Leak determination means for determining leakage of
A leak inspection apparatus characterized by comprising:   The leak determination means includes a first time until the pressure changes from the first pressure value to the second pressure value in the first state, and the pressure from the first pressure value to the second pressure in the second state. A calculation unit that calculates a ratio to a second time until the value is changed, and a comparison unit that determines the leakage by comparing the ratio with a threshold value for leakage determination. Item 2. The leak inspection apparatus according to Item 1.   The leak inspection apparatus according to claim 1, wherein the pump depressurizes the inside of the container.   The leak inspection apparatus according to any one of claims 1 to 3, wherein the container is a fuel tank in which fuel evaporative gas is purged into an intake passage of an internal combustion engine.

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