JP2008002298A - Leakage inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leakage inspection device having a high degree of flexibility in selecting a pump. <P>SOLUTION: A leakage inspection device for inspecting leakage of evaporated fuel to the outside from an evaporation system 3 in which evaporated fuel produced in a fuel tank circulates is equipped with a reference hole 18 for communicating to the evaporation system 3, a pump 20 for communicating to the reference hole 18 on a side opposite to the evaporation system 3 and executing inspection operation forcing pressure acting on the evaporation system 3 through the reference hole 18, an inspection means for inspecting an inspection side pressure loss ΔPi occurring in the evaporation system 3 due to the inspection operation and a reference side pressure loss ΔPb occurring in the reference hole 18 due to the inspection operation, and a determination means for determining leakage through the comparison between the inspection side pressure loss ΔPi and reference side pressure loss ΔPb inspected by the inspection means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a leak inspection apparatus for inspecting a leakage of evaporated fuel from an evaporation system through which evaporated fuel generated in a fuel tank flows.

Conventionally, a leak test that determines the leak by individually applying the pump pressure to the evaporation system and the reference hole by switching the passage, and comparing the pressure loss generated in the reference hole and the evaporation system by the pressure action. An apparatus is known (see, for example, Patent Document 1). In such a leak inspection apparatus, a pressure loss ΔP1 that occurs when the pump pressure is substantially applied only to the evaporation system, and a pressure loss ΔP2 that is generated when the pump pressure is substantially applied only to the reference hole. The greater the difference is, the higher the leak determination accuracy is. Here, as shown in FIGS. 10A and 10B, the magnitude of the difference between the pressure losses ΔP1 and ΔP2 is the pressure-flow rate characteristic of the pump that is held constant when the pressure losses ΔP1 and ΔP2 are detected (hereinafter referred to as the pressure loss ΔP1 and ΔP2). , Referred to as PQ characteristics). Therefore, it is desirable that the slope of the PQ characteristic curve of the pump is small in order to increase the accuracy of determining the leak.
JP 2004-28060 A

  However, in a non-displacement pump such as a centrifugal pump, the slope of the PQ characteristic curve generally increases as shown in FIG. Therefore, in order to realize a PQ characteristic curve with a small inclination as shown in FIG. 10A, it is necessary to select a positive displacement pump such as a vane pump. Here, positive displacement pumps tend to be more expensive than non-positive displacement pumps, and pump efficiency tends to be low, so the degree of freedom in selecting pumps is limited. Can not fully respond to.

  The present invention has been made in view of such problems, and it is an object of the present invention to provide a leak inspection apparatus having a high degree of freedom in selecting a pump.

  According to the first aspect of the present invention, the inspection side pressure loss generated in the evaporation system by the inspection operation of the pump that applies pressure to the evaporation system through the reference hole, and the reference side pressure loss generated in the reference hole by the inspection operation The size ratio changes depending on the size ratio between the leak hole of the evaporation system and the reference hole. Therefore, by comparing the inspection-side pressure loss detected by the detection means and the reference-side pressure loss, it is possible to correctly determine the leak through the evaporation system leak hole. In addition, since both the inspection side pressure loss and the reference side pressure loss to be compared are generated by the pressure action on the evaporation system through the reference hole, the leakage hole of the evaporation system and the reference in the state of occurrence of the pressure loss. The flow rates of fluid flowing through the holes are equal to each other. As a result, the magnitude ratio between the inspection-side pressure loss and the reference-side pressure loss does not depend on the fluid flow rate in each hole determined by the PQ characteristic of the pump, so the PQ characteristic of the pump affects the determination of leakage. Can be avoided. According to the first aspect of the present invention, since the degree of freedom of selection of the pump is increased, it is possible to realize accurate leak determination while using the pump according to the request to the apparatus.

  The pressure acting on the evaporation system through the reference hole by the inspection operation of the pump may be a negative pressure as in the second aspect of the invention or a positive pressure as in the third aspect of the invention. It may be.

  According to the invention described in claim 4, since the pump is steadily operated at the time of executing the inspection operation, when detecting the inspection-side pressure loss and the reference-side pressure loss, the fluctuation of the pressure loss can be reduced. it can. Therefore, it is possible to accurately detect the inspection-side pressure loss and the reference-side pressure loss and improve the accuracy of the leak determination by comparing the pressure losses.

  When the evaporation system leak hole and the reference hole are equal in size, it can be assumed that the inspection-side pressure loss and the reference-side pressure loss are also equal. Further, the larger the evaporation leak hole, the smaller the inspection-side pressure loss. Therefore, according to the fifth aspect of the present invention, when the inspection side pressure loss is equal to or less than the reference side pressure loss, it is determined that a leak has occurred. Therefore, an abnormal situation in which a leak occurs through a leak hole larger than the reference hole. Can be determined correctly.

  When the inspection-side pressure loss and the reference-side pressure loss change with time, the magnitude ratio between these pressure losses also changes. Therefore, according to the invention described in claim 6, since the inspection-side pressure loss and the reference-side pressure loss that are generated at the same time by the inspection operation of the pump are detected, it is possible to prevent the determination accuracy from deteriorating due to the temporal change of the pressure loss. can do.

  When there is a leak hole in the evaporation system, a pressure loss occurs between the reference hole side of the evaporation system and the outside of the system when the pressure due to the inspection operation of the pump acts on the evaporation system through the reference hole. Therefore, according to the invention described in claim 7, the pressure difference between the reference hole side of the evaporation system and the outside of the system is detected as the inspection-side pressure loss.

  In general, since the leak inspection apparatus is used in the atmosphere, the pressure outside the evaporation system is atmospheric pressure. Therefore, according to the invention described in claim 8, since the differential pressure sensor measures the difference between the pressure on the reference hole side of the evaporation system and the atmospheric pressure, the measurement result is different from that on the reference hole side of the evaporation system. Is equal to the pressure difference. Therefore, the configuration necessary for detecting the inspection-side pressure loss can be a relatively simple configuration using one differential pressure sensor.

  As described above, the pressure outside the evaporation system is generally atmospheric pressure. Therefore, according to the invention described in claim 9, the calculated value of the difference between the result of measuring the absolute pressure on the reference hole side of the evaporation system by the absolute pressure sensor and the result of measuring the atmospheric pressure by the atmospheric pressure sensor is It becomes equal to the pressure difference between the reference hole side of the system and the outside of the system. Here, since the absolute pressure sensor has fewer input ports communicating with the measurement target than the differential pressure sensor, the cost of measures such as deterioration and leaks due to the evaporative fuel entering the input port from the measurement target is reduced. Less is enough. Therefore, it is possible to construct a configuration necessary for detecting the inspection-side pressure loss at a relatively low cost.

  According to the invention described in claim 10, the absolute pressure between the reference hole formed in the reference passage and the evaporation system in the reference passage provided between the evaporation system and the pump is the absolute pressure on the reference hole side of the evaporation system. Since it can be said that it is a pressure, it can be measured by an absolute pressure sensor and used for detection of inspection-side pressure loss. In addition, since the atmospheric pressure sensor measures the atmospheric pressure outside the reference passage, the atmospheric pressure sensor can be prevented from interfering with the absolute pressure measurement in the reference passage.

  According to the eleventh aspect of the present invention, in the reference passage provided between the evaporation system and the pump, the absolute pressure between the reference hole formed by the reference passage and the evaporation system is the absolute pressure on the reference hole side of the evaporation system. Since it can be said that it is a pressure, it can be measured by an absolute pressure sensor and used for detection of inspection-side pressure loss. Further, since the atmospheric pressure sensor measures the atmospheric pressure in the reference passage opened by the opening control means with respect to the atmosphere, the atmospheric pressure can be surely flowed into the reference passage to realize accurate atmospheric pressure measurement. Furthermore, the opening control means opens the reference passage to the atmosphere when measuring the atmospheric pressure, but blocks the reference passage from the atmosphere when measuring the absolute pressure in the reference passage. It is possible to reliably avoid a situation in which the atmosphere flows into the reference passage from other than the leak hole and causes a measurement error.

  According to the twelfth aspect of the present invention, the absolute pressure between the reference hole formed in the reference passage and the evaporation system in the reference passage provided between the evaporation system and the pump is the absolute pressure on the reference hole side of the evaporation system. Since it can be said that it is a pressure, it can be measured by an absolute pressure sensor and used for detection of inspection-side pressure loss. In addition, since the atmospheric pressure sensor also uses the reference passage opened to the atmosphere through the stopped pump for atmospheric pressure measurement, it is possible to reduce the number of parts of the device, simplify the configuration, and reduce the cost. it can.

  The absolute pressure measured by the absolute pressure sensor in the reference passage opened to the atmosphere is equal to the atmospheric pressure. Therefore, according to the invention described in claim 13, since the absolute pressure sensor also serves as an atmospheric pressure sensor for measuring the atmospheric pressure in the reference passage, the number of parts of the device can be reduced to simplify the configuration and reduce the cost. Can be planned.

  When pressure acts on the evaporation system through the reference hole due to the inspection operation of the pump, pressure loss occurs on both sides of the reference hole. Therefore, according to the inventions of claims 14, 17 and 19, a pressure difference between both sides of the reference hole is detected as a reference side pressure loss.

  According to the fifteenth aspect of the invention, since the differential pressure sensor measures the difference between the evaporation system side pressure and the pump side pressure of the reference hole, it can be said that the measurement result is a pressure difference between both sides of the reference hole. . Therefore, the configuration necessary for detecting the reference side pressure loss can be a relatively simple configuration using one differential pressure sensor.

  According to the invention described in claims 16, 17, and 19, the absolute pressure on the evaporation system side of the reference hole is measured by the first absolute pressure sensor, and the absolute pressure on the pump side of the reference hole is measured by the second absolute pressure sensor. The calculated difference from the measured result is equal to the pressure difference on both sides of the reference hole. Here, since the absolute pressure sensor has fewer input ports communicating with the measurement target than the differential pressure sensor, the cost of measures such as deterioration and leaks due to the evaporative fuel entering the input port from the measurement target is reduced. Less is enough. Therefore, a configuration necessary for detecting the reference side pressure loss can be constructed at a relatively low cost.

  The absolute pressure measured by the second absolute pressure sensor in the reference passage opened to the atmosphere is equal to the atmospheric pressure. Therefore, according to the invention described in claim 17, since the second absolute pressure sensor also serves as an atmospheric pressure sensor that measures the atmospheric pressure in the communication passage, the number of parts of the device is reduced, the configuration is simplified, and the cost is reduced. Can be achieved.

  In the reference passage that forms the reference hole between the evaporation system and the pump, it can be said that the absolute pressure on the evaporation system side of the reference hole measured by the first absolute pressure sensor is the absolute pressure on the reference hole side of the evaporation system. Therefore, according to the invention described in claims 18 and 19, the first absolute pressure sensor also serves as an absolute pressure sensor for measuring the absolute pressure on the reference hole side of the evaporation system in the reference passage, thereby reducing the number of parts of the device. Therefore, the configuration can be simplified and the cost can be reduced.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment.

(First embodiment)
FIG. 1 shows an evaporated fuel processing apparatus 1 as a leak inspection apparatus according to a first embodiment of the present invention. The evaporated fuel processing apparatus 1 is mounted on a vehicle and processes evaporated fuel generated in the fuel tank 2. The evaporative fuel processing apparatus 1 includes an evaporation system 3, an inspection system 10, an electronic control unit (ECU) 50, and the like.

  The evaporation system 3 includes a fuel tank 2, a canister 8, an introduction passage 4, a purge passage 5, and a purge valve 6.

  The canister 8 is formed by filling an adsorbent 8 a such as activated carbon into the case 8 b and communicates with the fuel tank 2 through the introduction passage 4. Thus, the evaporated fuel generated in the fuel tank 2 flows into the case 8b of the canister 8 through the introduction passage 4, and is adsorbed by the adsorbent 8a so as to be desorbed.

  The purge passage 5 communicates between the canister 8 and the intake passage 9 of the internal combustion engine. Thereby, the evaporated fuel desorbed from the adsorbent 8 a of the canister 8 can be purged to the intake passage 9 through the purge passage 5. The evaporated fuel purged into the intake passage 9 is burned together with the injected fuel from the fuel injection valve in the internal combustion engine.

  The purge valve 6 is an electromagnetically driven two-way valve and is installed on the purge passage 5. The purge valve 6 adjusts the purge of the evaporated fuel into the intake passage 9 by opening and closing the purge passage 5.

  The inspection system 10 includes a reference passage 12, pressure guide passages 14 to 17, an atmospheric passage 19, a pump 20, a first differential pressure sensor 30, a second differential pressure sensor 32, and an open control valve 40.

  The reference passage 12 communicates with the canister 8 on the opposite side of the passages 4 and 5 across the adsorbent 8a. An orifice-shaped reference hole 18 is formed in the middle portion of the reference passage 12 to reduce the passage area. The passage area of the reference hole 18 is set to a value equal to or less than the total area of the leak holes allowed in the evaporation system 3 by law or the like.

  The pump 20 is an electric pump, and is installed on the opposite side of the canister 8 with the reference passage 12 interposed therebetween. In the present embodiment, a pump 20 having a constant fluid suction / discharge direction is used, the suction port 22 of the pump 20 communicates with the reference passage 12, and the discharge port 24 of the pump 20 is opened to the atmosphere. ing. Accordingly, the pump 20 can perform an inspection operation (hereinafter simply referred to as an inspection operation) in which the reference passage 12 is depressurized and a negative pressure is applied to the evaporation system 3 through the reference passage 12.

  The first differential pressure sensor 30 is an electric sensor that measures a pressure difference between the input ports 34 and 35. Here, one input port 34 communicates between the canister 8 and the reference hole 18 in the reference passage 12 through the pressure guide passage 14, and the other input port 35 is opened to the atmosphere through the pressure guide passage 17. ing. Thereby, the first differential pressure sensor 30 can measure the difference between the pressure on the reference hole 18 side of the evaporation system 3 and the atmospheric pressure outside the evaporation system 3.

  The second differential pressure sensor 32 is an electric sensor that measures a pressure difference between the input ports 36 and 37. Here, one input port 36 communicates between the canister 8 and the reference hole 18 in the reference passage 12 through the pressure guide passage 15, and the other input port 37 passes through the pressure guide passage 16 in the reference passage 12. The reference hole 18 communicates with the pump 20. Thereby, the second differential pressure sensor 32 can measure the difference between the pressure on the evaporation system 3 side of the reference hole 18 and the pressure on the pump 20 side of the reference hole 18.

  The opening control valve 40 is an electromagnetically driven two-way valve and is installed on the atmospheric passage 19. Here, one end of the atmospheric passage 19 communicates between the canister 8 and the reference hole 18 in the reference passage 12, and the other end of the atmospheric passage 19 is open to the atmosphere. Therefore, the opening control valve 40 opens or closes the reference passage 12 with respect to the atmosphere by opening and closing the atmosphere passage 19.

  The ECU 50 is mainly composed of a microcomputer having a CPU and a memory. The ECU 50 is electrically connected to the valves 6, 40, the pump 20, and the differential pressure sensors 30, 32, and controls the operation of these connecting elements. The ECU 50 may have a control function for the internal combustion engine, or may not have such a control function.

  Next, the principle of inspection for leakage from the evaporation system 3 to the outside of the system jointly performed by the inspection system 10 and the ECU 50 will be described.

  Since the negative pressure acts on the evaporation system 3 through the reference passage 12 between the pump 20 and the evaporation system 3 during the inspection operation of the pump 20, a leak hole 60 exists in the evaporation system 3 as schematically shown in FIG. In this case, a fluid flow is generated from the outside of the evaporation system 3 toward the pump 20 via the leak hole 60 and the reference hole 18 in order. At this time, the pressure loss ΔPi generated in the evaporation system 3 can be expressed by a pressure difference between the reference hole 18 side of the evaporation system 3 to be measured by the first differential pressure sensor 30 and the outside of the system. At this time, the pressure loss ΔPb generated in the reference passage 12 can be represented by a pressure difference (so-called differential pressure before and after) on both sides of the reference hole 18 which is a measurement target of the second differential pressure sensor 32.

Now, since the leak hole 60 that causes a leak is usually smaller than the passage area of the evaporation system 3, the pressure loss ΔPi generated in the evaporation system 3 is dominated by the pressure loss generated in the leakage hole 60. Therefore, since the pressure loss ΔPi in the evaporation system 3 can be considered to be substantially equal to the pressure loss in the leak hole 60, the correlation between the pressure loss ΔPi and the flow rate Qi in the leak hole 60 is expressed by the following equation (1). It is represented by In equation (1), αi represents the flow coefficient of the leak hole 60, Ai represents the total area of the leak hole 60, and ρi represents the density of the circulating fluid in the leak hole 60.
Qi = αi · Ai · (2 · ΔPi / ρi) ^1/2 (1)

On the other hand, since the reference hole 18 narrows the passage area of the reference passage 12, the pressure loss ΔPb generated in the reference passage 12 is dominated by the pressure loss generated in the reference hole 18. Therefore, since the pressure loss ΔPb in the reference passage 12 can be considered to be substantially equal to the pressure loss in the reference hole 18, the correlation between the pressure loss ΔPb and the flow rate Qb in the reference hole 18 is expressed by the following equation (2). It is represented by In equation (2), αb represents the flow coefficient of the reference hole 18, Ab represents the passage area of the reference hole 18, and ρb represents the density of the circulating fluid in the reference hole 18.
Qb = αb · Ab · (2 · ΔPb / ρb) ^1/2 (2)

When the above-described fluid flow is generated by the inspection operation of the pump 20, the flow rate Qi in the leak hole 60 and the flow rate Qb in the reference hole 18 coincide. Therefore, the following formula (3) is obtained from the above formulas (1) and (2), and the following formula (4) is obtained by rearranging the formula (3).
αi · Ai · (2 · ΔPi / ρi) ^1/2 = αb · Ab · (2 · ΔPb / ρb) ^1/2 (3)
ΔPi / ΔPb = ρi / ρb · {(αb · Ab) / (αi · Ai)} ² (4)

According to the above equation (4), it can be seen that the magnitude ratio ΔPi / ΔPb depends on a physical quantity unrelated to the PQ characteristic of the pump 20. Further, assuming that the fluid densities ρi and ρb are approximately equal as in the following formula (5), the following formula (6) is established and the size ratio ΔPi / ΔPb is established when the sizes of the holes 18 and 60 are equal. The value of the magnitude ratio ΔPi / ΔPb decreases as the value of “1” becomes “1” and the total area Ai of the leak hole 60 increases. Accordingly, when the value of the magnitude ratio ΔPi / ΔPb is “1” or less, that is, when the pressure loss ΔPi is less than or equal to the pressure loss ΔPb, the leakage from the leak hole 60 larger than the reference hole 18 occurs. Judge that there is. On the other hand, when the value of the magnitude ratio ΔPi / ΔPb exceeds “1”, that is, when the pressure loss ΔPi is larger than the pressure loss ΔPb, it is determined that there is no leakage from the leak hole 60. As described above, in this embodiment, the pressure loss ΔPi is defined as the inspection-side pressure loss ΔPi, and the pressure loss ΔPb is defined as the reference-side pressure loss ΔPb.
ρi≈ρb (5)
αi · Ai = αb · Ab (6)

  Next, the leak inspection process of the first embodiment performed by the inspection system 10 and the ECU 50 based on the above principle will be described with reference to the flowchart of FIG. The leak inspection process is started after the internal combustion engine is stopped by the ECU 50 executing a computer program stored in the memory. At the start of the leak inspection process, it is assumed that the purge valve 6 is in the closed state of the purge passage 5, the pump 20 is in the stopped state, and the open control valve 40 is in the open state of the atmospheric passage 19.

  In step S101 of the leak inspection process, the inspection operation of the pump 20 is started under the control of the ECU 50. At the same time, in step S101, the open control valve 40 is closed by the control of the ECU 50, and the reference passage 12 is blocked from the atmosphere.

  Next, in step S102, the first differential pressure sensor 30 measures the pressure difference between the reference hole 18 side of the evaporation system 3 and the outside of the system, and the ECU 50 detects the measurement result as an inspection-side pressure loss ΔPi. At the same time, in step S102, the second differential pressure sensor 32 measures the pressure difference between the evaporation system 3 side of the reference hole 18 and the pump 20 side, and the ECU 50 detects the measurement result as the reference side pressure loss ΔPb.

  In step S102 of the present embodiment, the pressure differences detected as the pressure losses ΔPi and ΔPb are simultaneously measured by the differential pressure sensors 30 and 32. Therefore, it can be said that the detected pressure losses ΔPi and ΔPb are pressure losses generated simultaneously by the inspection operation of the pump 20. In step S102 of the present embodiment, the pump 20 is steadily operated under the control of the ECU 50 until the measurement of at least two types of pressure differences is completed. Here, the steady operation of the pump 20 may be realized, for example, by controlling the rotational speed of the pump 20, may be realized by controlling the supply voltage to the pump 20, or may be realized by controlling the supply current to the pump 20. May be.

  In step S103 following step S102, the ECU 50 compares the pressure losses ΔPi and ΔPb detected in step S102 to determine leakage from the evaporation system 3. Specifically, if the inspection-side pressure loss ΔPi is equal to or less than the reference-side pressure loss ΔPb, it is determined that a leak has occurred and step S104 is executed. Then, the process proceeds to step S105. Here, in step S104, the occurrence of a leak is notified to the user of the vehicle, for example, by lighting an abnormal lamp on the instrument panel of the vehicle. On the other hand, if the inspection-side pressure loss ΔPi is larger than the reference-side pressure loss ΔPb, it is determined that no leak has occurred, and the process directly proceeds to step S105.

  In step S105, which is executed regardless of the result of the leak determination, the inspection operation of the pump 20 is stopped under the control of the ECU 50. At the same time, in step S104, the opening control valve 40 is opened by the control of the ECU 50, and the reference passage 12 is opened to the atmosphere.

  According to the first embodiment described above, since the leak is determined based on the magnitude ratio ΔPi / ΔPb that does not depend on the PQ characteristics of the pump 20 for the inspection-side and reference-side pressure losses ΔPi, ΔPb, the type of the pump 20 This can avoid the situation that affects the accuracy of leak determination.

  Further, according to the first embodiment, since the pressure losses ΔPi and ΔPb generated simultaneously by the steady operation of the pump 20 as the inspection operation are detected, the temporal changes in the pressure losses ΔPi and ΔPb and the characteristics of the pump 20 are detected. It is possible to prevent the leak determination accuracy from deteriorating due to fluctuations or the like.

  Furthermore, according to the first embodiment, the pressure differences detected as the inspection side and reference side pressure losses ΔPi and ΔPb are measured by the respective differential pressure sensors 30 and 32, which are necessary for detecting the pressure loss. The simple structure becomes relatively simple.

  Furthermore, according to the first embodiment, there is no need to provide a switching valve for switching the passage in the inspection system 10 as disclosed in the above-mentioned Patent Document 1, and for example, the opening control valve 40 composed of an on / off valve is provided in the inspection system 10. It is only necessary to provide it. Therefore, the cost for detecting the pressure loss can be reduced.

  According to such a first embodiment, an accurate leak determination can be realized with a relatively simple configuration while using the type of pump 20 that meets the demand for the evaporated fuel processing apparatus 1.

  In the first embodiment so far, the first differential pressure sensor 30 and the second differential pressure sensor 32 jointly constitute the “detecting means” recited in the claims, and the ECU 50 claims the claims. This corresponds to the “determination means”. The first differential pressure sensor 30 corresponds to the “differential pressure sensor for measuring the difference between the pressure on the reference hole side of the evaporation system and the atmospheric pressure” described in the claims, and the second differential pressure sensor 32 is patented. This corresponds to “a differential pressure sensor for measuring a difference between the pressure on the evaporation system side of the reference hole and the pressure on the pump side of the reference hole” recited in the claims.

(Second embodiment)
As shown in FIG. 4, the second embodiment of the present invention is a modification of the first embodiment. In the second embodiment, absolute pressure sensors 100 and 102 and an atmospheric pressure sensor 110 are provided instead of the differential pressure sensors 30 and 32, and the pressure guiding passages 15 and 17 are omitted accordingly.

  Specifically, the first absolute pressure sensor 100 is an electric sensor that measures the absolute pressure of the input port 104. Here, the input port 104 communicates between the canister 8 and the reference hole 18 in the reference passage 12 through the pressure guide passage 14. Thereby, the first absolute pressure sensor 100 can measure the absolute pressure between the evaporation system 3 and the reference hole 18. Here, the absolute pressure between the evaporation system 3 and the reference hole 18 can be said to be the absolute pressure on the reference hole 18 side of the evaporation system 3, and it can also be said to be the absolute pressure on the evaporation system 3 side of the reference hole 18.

  The second absolute pressure sensor 102 is an electric sensor that measures the absolute pressure of the input port 106. Here, the input port 106 communicates between the reference hole 18 in the reference passage 12 and the pump 20 through the pressure guiding passage 16. Thereby, the second absolute pressure sensor 102 can measure the pressure on the pump 20 side of the reference hole 18.

  The atmospheric pressure sensor 110 is an electric sensor that measures an absolute pressure outside the evaporation system 3, that is, an atmospheric pressure. The atmospheric pressure sensor 110 is installed outside the reference passage 12 at an appropriate location according to the specifications of the evaporated fuel processing apparatus 1 and measures the atmospheric pressure at the installation location.

  The absolute pressure sensors 100 and 102 and the atmospheric pressure sensor 110 are electrically connected to the ECU 50. The ECU 50 detects the absolute pressure between the evaporation system 3 and the reference hole 18 measured by the first absolute pressure sensor 100, that is, the absolute pressure on the reference hole 18 side of the evaporation system 3, and the evaporation measured by the atmospheric pressure sensor 110. The difference between the system 3 and the atmospheric pressure outside the system is calculated. This calculation result is substantially equal to the measurement result of the first differential pressure sensor 30 in the first embodiment. Further, the ECU 50 detects the absolute pressure between the evaporation system 3 and the reference hole 18 measured by the first absolute pressure sensor 100, that is, the absolute pressure on the evaporation system 3 side of the reference hole 18, and the second absolute pressure sensor 102. The difference between the measured reference hole 18 and the absolute pressure on the pump 20 side is calculated. This calculation result is substantially equal to the measurement result of the second differential pressure sensor 32 in the first embodiment. As described above, the two types of calculation results of the ECU 50 represent the inspection-side and reference-side pressure losses ΔPi and ΔPb, respectively, so that the leak can be inspected based on the same principle as in the first embodiment.

  Therefore, the leak inspection process of the second embodiment will be described below with reference to the flowchart of FIG. First, in step S <b> 201, the atmospheric pressure is measured by the atmospheric pressure sensor 110. The next step S202 is the same as step S101 of the first embodiment.

  In subsequent step S203, the first absolute pressure sensor 100 measures the absolute pressure between the evaporation system 3 and the reference hole 18 (hereinafter referred to as “first absolute pressure”), and the second absolute pressure sensor 102 uses the reference hole. The 18 absolute pressures on the pump 20 side (hereinafter referred to as “second absolute pressure”) are measured. Further, in step S204, the ECU 50 calculates the difference between the atmospheric pressure and the first absolute pressure measured in steps S201 and S203 and the difference between the first absolute pressure and the second absolute pressure measured in step S203. The calculation results are detected as an inspection side pressure loss ΔPi and a reference side pressure loss ΔPb, respectively.

  Now, in step S203 of this embodiment, in order to obtain the pressure difference detected as each pressure loss ΔPi, ΔPb in step S204, respectively, the first and second absolute pressures are respectively set to the first and second absolute pressure sensors 100, Measure simultaneously with 102. Here, since it can be assumed that the atmospheric pressure does not change during the leak inspection process performed in a relatively short time, the pressure losses ΔPi and ΔPb detected by the simultaneous measurement of the absolute pressure are the inspections of the pump 20. It can be considered that the pressure loss is generated simultaneously by the operation. In step S203 of the present embodiment, the pump 20 is steadily operated under the control of the ECU 50 until measurement of at least two types of absolute pressures is completed.

  After the above, in step S205, each pressure loss ΔPi, ΔPb detected in step S204 is compared in the same manner as in step S103 of the first embodiment to determine a leak. Subsequent steps S206 and 207 are the same as steps S104 and 105 of the first embodiment.

  Also according to the second embodiment, the pressure determination does not affect the determination accuracy by the leak determination based on the magnitude ratio ΔPi / ΔPb that does not depend on the pump characteristics, and the pressure loss that is simultaneously generated by the steady operation of the pump 20 is detected. Therefore, it is possible to prevent the determination accuracy from deteriorating.

  In addition, according to the second embodiment, since the absolute pressure sensors 100 and 102 are used instead of the differential pressure sensors 30 and 32, the input ports through which the evaporated fuel enters from the reference passage 12 in the sensors 100 and 102 are used. The number is smaller than that of the differential pressure sensors 30 and 32. From this, the absolute pressure sensors 100 and 102 have a lower cost for measures such as deterioration due to the invasion of evaporated fuel and leaks than the differential pressure sensors 30 and 32. Therefore, a configuration for detecting pressure loss is inexpensively constructed. can do.

  Further, according to the second embodiment, the absolute pressure on the reference hole 18 side of the evaporation system 3 necessary for detecting the inspection side pressure loss ΔPi and the evaporation system 3 side of the reference hole 18 necessary for detecting the reference side pressure loss ΔPb are described. Is measured by the same absolute pressure sensor 100. Therefore, the number of parts for detecting the pressure loss can be reduced, thereby simplifying the configuration and reducing the cost.

  Furthermore, according to the second embodiment, since the atmospheric pressure sensor 110 measures the atmospheric pressure outside the reference passage 12, the atmospheric pressure sensor 100 can be prevented from interfering with the measurement of the first and second absolute pressures. .

  In the second embodiment so far, the first absolute pressure sensor 100, the second absolute pressure sensor 102, and the ECU 50 jointly constitute the “detecting means” described in the claims. The first absolute pressure sensor 100 also serves as a sensor corresponding to the “absolute pressure sensor” recited in the claims, and the ECU 50 includes the “measurement results of the absolute pressure sensor and the atmospheric pressure sensor recited in the claims”. And a “calculator that calculates the difference between the measurement result of the first absolute pressure sensor and the measurement result of the second absolute pressure sensor”.

(Third embodiment)
As shown in FIGS. 6 and 7, the third embodiment of the present invention is a modification of the second embodiment. In the third embodiment, the atmospheric pressure sensor 110 is not provided, and a part of the content of the leak inspection process is different from the second embodiment.

  Specifically, in the leak inspection process of the third embodiment, the absolute pressure is measured by the first absolute pressure sensor 100 or the second absolute pressure sensor 102 in step S301 instead of step S201 of the second embodiment. At this time, the opening control valve 40 opens the reference passage 12 to the atmosphere by the same open state of the air passage 19 as at the start of processing, and the pump 20 is in the same stopped state as at the start of processing, so that the absolute pressure to be measured is measured. Becomes equal to atmospheric pressure. Subsequent steps S302 to S307 are the same as steps S202 to S207 of the second embodiment.

  According to the third embodiment, since the atmospheric pressure is measured in the reference passage 12 opened to the atmosphere by the opening control valve 40, the atmospheric pressure is accurately measured by reliably flowing the atmosphere into the reference passage 12. be able to.

  Further, according to the third embodiment, the first or second absolute pressure and the atmospheric pressure necessary for pressure loss detection are measured by the same absolute pressure sensor, so the number of parts for pressure loss detection is reduced. Therefore, the configuration can be simplified and the cost can be reduced.

  Further, according to the third embodiment, even if the reference passage 12 is opened to the atmosphere in step S301 for atmospheric pressure measurement, after the reference passage 12 is blocked from the atmosphere by S302, the first and second steps in step S303 are performed. A second absolute pressure is measured. Therefore, it is possible to reliably avoid a situation in which the atmosphere flows into the reference passage 12 from other than the leak hole 60 of the evaporation system 3 during the measurement of the first and second absolute pressures and causes a measurement error.

  In the third embodiment so far, the opening control valve 40 corresponds to “opening control means” described in the claims. Moreover, the sensor which measures atmospheric pressure in step S301 among the 1st absolute pressure sensor 100 and the 2nd absolute pressure sensor 102 is equivalent to the "atmospheric pressure sensor" as described in a claim.

(Fourth embodiment)
As shown in FIG. 8, the fourth embodiment of the present invention is a modification of the third embodiment. In the fourth embodiment, a part of the content of the leak inspection process is different from the third embodiment.

  Specifically, in the leak inspection process of the fourth embodiment, in step S401, the open control valve 40 is closed by the atmospheric passage 19 under the control of the ECU 50, and the reference passage 12 is shut off from the atmosphere. The absolute pressure is measured by the first absolute pressure sensor 100 or the second absolute pressure sensor 102. At this time, the pump 20 is in the same stop state as that at the start of the process, and the reference passage 12 is opened to the atmosphere through the pump 20, so that the absolute pressure measured becomes equal to the atmospheric pressure. The subsequent steps S403 to S408 are the same as steps S302 to S307 in the third embodiment.

  According to the fourth embodiment, since the reference passage 12 opened to the atmosphere through the pump 20 in the stopped state is also used for atmospheric pressure measurement, the number of parts for detecting pressure loss is reduced. Simplification and cost reduction can be achieved.

  Although a plurality of embodiments of the present invention have been described above, the present invention is not construed as being limited to these embodiments, and can be applied to various embodiments without departing from the scope of the present invention. .

  For example, in the first to fourth embodiments, the pump 20 may not be steadily operated during the inspection operation. Further, in the first to fourth embodiments, as shown in FIG. 9 (the figure is an example of the first embodiment), the discharge port 24 communicates with the reference passage 12 in the pump 20 in which the fluid suction and discharge directions are constant. In addition, the suction port 22 may be opened to the atmosphere. In this case, since the positive pressure acts on the evaporation system 3 through the reference passage 12 during the inspection operation of the pump 20, when the leak hole 60 exists in the evaporation system 3, the pump 20 sequentially passes through the reference hole 18 and the leak hole 60. Thus, a fluid flow toward the outside of the evaporation system 3 is generated. Furthermore, in the first to fourth embodiments, a pump having a variable fluid suction / discharge direction may be used in place of the pump 20.

  In the first to fourth embodiments, in order to further improve the determination accuracy of the leak, the magnitude ratio of the pressure loss ΔPi, ΔPb is grasped by the above equation (4) considering the ratio of the fluid density ρi, ρb, and the leak is reduced. You may make it determine. In the first to fourth embodiments, the fuel vapor state such as the fuel vapor concentration may be measured using the inspection system 10 or the ECU 50, and the purge to the intake passage 9 may be assisted using the pump 20. May be.

  In the first embodiment, instead of the first differential pressure sensor 30, a first absolute pressure sensor 100 and an atmospheric pressure sensor 110 that measure the first absolute pressure and the atmospheric pressure, respectively, by a method according to the second embodiment may be provided. Good. Moreover, in 1st embodiment, it replaced with the 1st differential pressure sensor 30, and provided the 1st absolute pressure sensor 100 which measures both 1st absolute pressure and atmospheric pressure by the method according to 3rd or 4th embodiment. Also good. Furthermore, in step S102 of the first embodiment, the pressure difference measurement by the first differential pressure sensor 30 and the pressure difference measurement by the second differential pressure sensor 32 may be performed back and forth.

  In step S203 of the second embodiment, the measurement of the first absolute pressure by the first absolute pressure sensor 100 and the measurement of the second absolute pressure by the second absolute pressure sensor 102 may be performed back and forth.

  In the third and fourth embodiments, the atmospheric pressure sensor 110 of the second embodiment may be installed in the reference passage 12 and the atmospheric pressure may be measured by the atmospheric pressure sensor 110. In step S301 of the third embodiment and step S402 of the fourth embodiment, the atmospheric pressure is measured by each of the first and second absolute pressure sensors 100 and 102, and for example, the average of the measurement results is taken. The measurement accuracy of atmospheric pressure may be increased.

It is a schematic diagram which shows the structure of the evaporative fuel processing apparatus by 1st embodiment. It is a schematic diagram for demonstrating the inspection principle of the leak by 1st embodiment. It is a flowchart which shows the leak test process by 1st embodiment. It is a schematic diagram which shows the structure of the evaporative fuel processing apparatus by 2nd embodiment. It is a flowchart which shows the leak test process by 2nd embodiment. It is a schematic diagram which shows the structure of the evaporative fuel processing apparatus by 3rd embodiment. It is a flowchart which shows the leak test process by 3rd embodiment. It is a flowchart which shows the leak test process by 4th embodiment. It is a schematic diagram which shows the structure of a modification. It is a schematic diagram which shows the characteristic of a conventional apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Evaporative fuel processing apparatus (leakage inspection apparatus), 2 Fuel tank, 3 Evaporation system, 10 Inspection system, 12 Reference passage, 14, 15, 16, 17 Guide passage, 18 Reference hole, 19 Atmospheric passage, 20 Pump, 22 Suction port, 24 discharge port, 30 first differential pressure sensor (detection means, differential pressure sensor), 32 second differential pressure sensor (detection means, differential pressure sensor), 34, 35, 36, 37, 104, 106 input port 40 open control valve (open control means), 50 ECU (determination means, detection means, calculation unit), 60 leak hole, 100 first absolute pressure sensor (absolute pressure sensor, atmospheric pressure sensor), 102 second absolute pressure sensor (Atmospheric pressure sensor), 110 atmospheric pressure sensor, ΔPb reference side pressure loss, ΔPi inspection side pressure loss, ΔPi / ΔPb magnitude ratio

Claims (19)

A leak inspection apparatus for inspecting a leak of evaporated fuel from an evaporation system through which evaporated fuel generated in a fuel tank flows,
A reference hole communicating with the evaporation system;
A pump that communicates with the reference hole on the opposite side of the evaporation system, and that performs an inspection operation that applies pressure to the evaporation system through the reference hole;
Detection means for detecting an inspection-side pressure loss generated in the evaporation system by the inspection operation and a reference-side pressure loss generated in the reference hole by the inspection operation;
Determination means for determining the leak by comparing the inspection-side pressure loss detected by the detection means and the reference-side pressure loss;
A leak inspection apparatus comprising:   The leak inspection apparatus according to claim 1, wherein the pressure acting on the evaporation system through the reference hole by the inspection operation is a negative pressure.   The leak inspection apparatus according to claim 1, wherein a pressure acting on the evaporation system through the reference hole by the inspection operation is a positive pressure.   The leak inspection apparatus according to any one of claims 1 to 3, wherein the pump is steadily operated when the inspection operation is performed.   5. The leak test according to claim 1, wherein the determination unit determines that the leak has occurred when the test-side pressure loss is equal to or less than the reference-side pressure loss. apparatus.   6. The leak inspection apparatus according to claim 1, wherein the detection unit detects the inspection-side pressure loss and the reference-side pressure loss that are simultaneously generated by the inspection operation.   The leak test according to any one of claims 1 to 6, wherein the detection means detects a pressure difference between the reference hole side of the evaporation system and the outside of the system as the inspection-side pressure loss. apparatus.   The leak inspection apparatus according to claim 7, wherein the detection unit includes a differential pressure sensor that measures a difference between a pressure on the reference hole side of the evaporation system and an atmospheric pressure. The detection means includes
An absolute pressure sensor for measuring the absolute pressure on the reference hole side of the evaporation system;
An atmospheric pressure sensor for measuring atmospheric pressure;
A calculation unit for calculating a difference between the measurement result of the absolute pressure sensor and the measurement result of the atmospheric pressure sensor;
The leak inspection apparatus according to claim 7, further comprising: A reference passage provided between the evaporation system and the pump, and forming the reference hole;
The absolute pressure sensor measures an absolute pressure between the evaporation system and the reference hole in the reference passage,
The leak inspection apparatus according to claim 9, wherein the atmospheric pressure sensor measures an atmospheric pressure outside the reference passage. A reference passage provided between the evaporation system and the pump and forming the reference hole;
Opening control means for opening or blocking the reference passage to the atmosphere;
With
The absolute pressure sensor measures the absolute pressure between the evaporation system and the reference hole in the reference passage blocked from the atmosphere by the opening control means,
The leak inspection apparatus according to claim 9, wherein the atmospheric pressure sensor measures an atmospheric pressure in the reference passage opened to the atmosphere by the opening control unit. A reference passage provided between the evaporation system and the pump, and forming the reference hole;
The absolute pressure sensor measures an absolute pressure between the evaporation system and the reference hole in the reference passage subjected to a pressure action by the inspection operation of the pump;
The leak inspection apparatus according to claim 9, wherein the atmospheric pressure sensor measures an atmospheric pressure in the reference passage opened to the atmosphere through the pump in a stopped state.   The leak inspection apparatus according to claim 11, wherein the absolute pressure sensor also serves as an atmospheric pressure sensor.   The leak detection apparatus according to claim 1, wherein the detection unit detects a pressure difference between both sides of the reference hole as the reference side pressure loss.   15. The leak inspection apparatus according to claim 14, wherein the detection unit includes a differential pressure sensor that measures a difference between a pressure on the evaporation system side of the reference hole and a pressure on the pump side of the reference hole. . The detection means includes
A first absolute pressure sensor for measuring an absolute pressure on the evaporation system side of the reference hole;
A second absolute pressure sensor for measuring an absolute pressure on the pump side of the reference hole;
A calculation unit for calculating a difference between the measurement result of the first absolute pressure sensor and the measurement result of the second absolute pressure sensor;
15. The leak inspection apparatus according to claim 14, further comprising: The detecting means for detecting a pressure difference between both sides of the reference hole as the reference side pressure loss,
A first absolute pressure sensor for measuring an absolute pressure on the evaporation system side of the reference hole in the reference passage;
A second absolute pressure sensor for measuring an absolute pressure on the pump side of the reference hole in the reference passage;
A calculation unit for calculating a difference between the measurement result of the first absolute pressure sensor and the measurement result of the second absolute pressure sensor;
With
The leak inspection apparatus according to claim 11, wherein the second absolute pressure sensor also serves as the atmospheric pressure sensor.   The leak inspection apparatus according to claim 17, wherein the first absolute pressure sensor also serves as the absolute pressure sensor. The detecting means for detecting a pressure difference between both sides of the reference hole as the reference side pressure loss,
A first absolute pressure sensor for measuring an absolute pressure on the evaporation system side of the reference hole in the reference passage;
A second absolute pressure sensor for measuring an absolute pressure on the pump side of the reference hole in the reference passage;
A calculation unit for calculating a difference between the measurement result of the first absolute pressure sensor and the measurement result of the second absolute pressure sensor;
With
The leak inspection apparatus according to claim 10, wherein the first absolute pressure sensor also serves as the absolute pressure sensor.

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