JP2018059422A - Fuel tank system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel tank system which accurately detects perforation by using a single pressure sensor.SOLUTION: An atmosphere release pipe 62, a negative pressure acting pipe 70 and a reference pipe 74 are arranged between a canister 14 and an atmosphere port 64. At the detection of perforation, an electromagnetic cutoff valve 66 is brought into a full-closed state, a pressure difference between the pressure of the whole of a system and atmospheric pressure is compared with a threshold as primary detection, and when the pressure difference is not larger than the threshold, secondary detection is performed. The reference pressure is detected by switching the electromagnetic cutoff valve 66 to a reference state, driving a key-off pump 72, and making negative pressure act on the reference pipe 74. Arrival pressure is detected by switching the electromagnetic cutoff valve 66 to a perforation detection state, driving the key-off pump 72, and supplying the negative pressure to the whole of a fuel tank system 10, and when the arrival pressure is higher than the reference pressure (when the negative pressure is low), the occurrence of the perforation is detected.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a fuel tank system.

  2. Description of the Related Art Conventionally, a fuel tank system has been used in which fuel vapor generated in a fuel tank is adsorbed by a canister and fuel vapor adsorbed by the canister is supplied to an engine side using negative pressure in an intake passage.

  By the way, in recent years, automobiles equipped with a motor for traveling together with an engine such as a hybrid automobile (HEV) have been put into practical use. Thus, in an automobile equipped with a motor for traveling, the period during which the engine is stopped during traveling may continue for a long time. Therefore, for example, as in Patent Document 1, a so-called sealed fuel tank system has been developed in which an on-off valve is provided between the fuel tank and the canister and the on-off valve is closed during the engine stop period.

  On the other hand, in the above fuel tank system, there is a risk of air pollution if fuel gas leaks from a pipe or the like. Therefore, it is obliged to automatically detect fuel gas leak (perforated detection).

  For example, in the fuel evaporative emission control device disclosed in Patent Document 1, the pressure sensor provided inside the fuel tank detects the perforation on the fuel tank side with respect to the on-off valve, and the pressure sensor provided on the air release side of the canister. It has been proposed to detect perforation on the canister side with respect to the on-off valve.

Japanese Patent Laying-Open No. 2015-190347

  When the perforation is detected while opening and closing the on-off valve provided between the fuel tank and the canister as in the fuel evaporative emission control device described in Patent Document 1, pressure sensors are respectively provided on the fuel tank side and the canister side. There was an inconvenience of having to provide.

  The present invention has been made in consideration of the above facts, and an object of the present invention is to provide a fuel tank system that accurately detects a hole with a single pressure sensor.

  According to the first aspect of the present invention, there is provided a fuel tank in which fuel is stored, a canister for introducing and adsorbing fuel vapor from the fuel tank, and supplying fuel vapor to an intake pipe, and the fuel tank and the canister A vapor passage connecting the introduction port, a purge passage connecting the supply port of the canister and the intake pipe, a first on-off valve provided in the purge passage and communicating or blocking the purge passage, and the canister A first passage that communicates the ventilation port with an air communication opening that opens to the outside; and a branch from the middle of the first passage, and joins the first passage on the air communication opening side of the branch position in the first passage A second passage that is provided in the second passage and that applies pressure to the canister side, and is provided at the branch position, and on the canister side of the first passage. A switching valve that selectively communicates with the atmosphere communication port side of the first passage or the second passage, or shuts off both the canister side of the first passage, and the switching valve of the first passage more than the switching valve. A third passage branched from the canister side and joined to the second passage on the canister side with respect to the pump of the second passage; provided in the third passage; the canister side of the third passage and the atmosphere A second on-off valve that communicates with or cuts off the communication port side, a pressure sensor that is provided on the canister side of the third passage relative to the second on-off valve, and that detects the pressure in the third passage; In the passage, a reference portion provided closer to the canister than the pressure sensor and in which the third passage is partially reduced in diameter, the switching valve, the first on-off valve, the second on-off valve, and the pump The While turning control, and a control unit that performs perforated determination system based on the detected value of the pressure sensor.

  The fuel tank system configured as described above can perform perforation detection control when the vehicle is parked (non-running). First, as a primary detection, the control unit shuts off the canister side of the first passage, the atmosphere communication port side of the first passage, and the second passage by switching the switching valve, and the third passage by switching the second on-off valve. Shut off. Further, the first on-off valve provided in the purge passage is closed. As a result, the entire fuel tank system is shut off from the outside. In this state, the control unit may determine that there is a possibility of perforation when the differential pressure between the internal pressure (third passage) detected by the pressure sensor and the atmospheric pressure is equal to or less than a preset threshold value. it can.

  If the control unit determines that there is a possibility of perforation, secondary detection can be performed. The control unit switches the switching valve to connect the canister side of the first passage and the atmosphere communication side of the first passage, and opens the on-off valve to connect the third passage. In this state, the control unit drives the pump to supply negative pressure to the third passage, and detects the pressure detected by the pressure sensor as the reference pressure. Since the negative pressure is supplied in a state where the third passage is in communication with the atmosphere communication side, this reference pressure is reduced when a hole having a diameter of the reduced reference portion is formed in the fuel tank system. This is considered to correspond to the pressure detected by the pressure sensor.

  Subsequently, the control unit switches the switching valve to connect the canister side of the first passage and the second passage, and closes the on-off valve to shut off the third passage. In this state, the controller drives the pump to supply negative pressure to the entire system via the second passage, and detects the pressure value detected by the pressure sensor as the ultimate pressure. The control unit can determine that the system is perforated when the ultimate pressure is larger than the reference pressure (the negative pressure is small).

  That is, by configuring the fuel system in this way, it is possible to detect the perforation of the entire fuel tank system with a single pressure sensor.

  According to a second aspect of the present invention, in the first aspect of the present invention, the control unit switches the switching valve to change the canister side of the first passage, the atmospheric communication port side of the first passage, and the second passage. The difference between the pressure value detected by the pressure sensor and the atmospheric pressure in a state where the passage is shut off, the first on-off valve and the second on-off valve are closed and the purge passage and the third passage are shut off. Primary detection that determines that there is no perforation when the differential pressure is greater than the threshold compared to a preset threshold, and when the differential pressure is less than or equal to the threshold in the primary detection, While switching the switching valve to connect the canister side of the first passage and the atmosphere communication port side of the first passage, the second on-off valve is switched to connect the third passage, A negative pressure is applied to the third passage by driving the pump. The reference pressure detected by the pressure sensor and the switching valve are switched to communicate with the canister side of the first passage and the second passage, and the purge passage and the third passage are shut off. In the state, the pump is driven to apply a negative pressure to the second passage to compare with the ultimate pressure detected by the pressure sensor, and when the ultimate pressure is larger than the reference pressure, there is a hole in the system. The secondary detection is performed to determine that it is open.

  The fuel tank system configured in this way performs perforation detection as follows. First, the control unit performs primary detection. The canister side of the first passage and the atmosphere communication side of the first passage and the second passage are shut off by switching the switching valve, and the purge passage and the third passage are shut off by switching the first on-off valve and the second on-off valve. To do. In this state, the control unit determines that there is no perforation when the pressure difference between the internal (third passage) pressure detected by the pressure sensor and the atmospheric pressure is greater than a preset threshold value.

  On the other hand, if the differential pressure is less than or equal to the threshold value in the primary detection, secondary detection is performed because the possibility of perforation cannot be denied.

  That is, the control unit opens the on-off valve and connects the third passage in a state where the canister side of the first passage and the atmosphere communication port side of the first passage are in communication. In this state, the pump is driven to supply a negative pressure to the third passage, and the pressure detected by the pressure sensor is detected as a reference pressure. Subsequently, the control unit switches the switching valve to communicate the canister side of the first passage with the second passage, and closes the second on-off valve to shut off the third passage. In this state, the control unit drives the pump to supply the negative pressure to the entire fuel tank system via the second passage, and detects the pressure detected by the pressure sensor as the ultimate pressure. The control unit determines that there is a hole in the system when the ultimate pressure is larger than the reference pressure (the negative pressure is small).

  Thus, the perforation of the entire fuel tank system can be detected by a single pressure sensor.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the switching valve and the second on-off valve are integrated with each other.

  With this configuration, the functions of the switching valve and the second on-off valve can be achieved simply by controlling the integrated valve body. That is, the control system becomes simple.

  Since the fuel tank system according to the first or second aspect of the present invention has the above-described configuration, the entire system can be detected with a single pressure sensor.

  Since the fuel tank system according to the third aspect of the present invention is configured as described above, the control system is simplified.

It is a figure showing the whole fuel tank system schematic structure concerning one embodiment of the present invention. It is a figure showing the important section composition of the fuel tank system concerning one embodiment of the present invention. It is a whole schematic block diagram which shows the fuel supply state of the fuel tank system which concerns on one Embodiment of this invention. It is a principal part block diagram which shows the fuel supply state of the fuel tank system which concerns on one Embodiment of this invention. It is a whole schematic block diagram which shows the engine drive running state of the fuel tank system which concerns on one Embodiment of this invention. It is a principal part block diagram which shows the engine drive running state of the fuel tank system which concerns on one Embodiment of this invention. It is a whole schematic block diagram which shows the fully closed state (primary detection state in perforation detection control) of the fuel tank system which concerns on one Embodiment of this invention. It is a principal part block diagram which shows the fully closed state (primary detection state in perforation detection control) of the fuel tank system which concerns on one Embodiment of this invention. It is a principal part block diagram which shows the reference pressure detection state in the secondary detection of the perforation detection control of the fuel tank system which concerns on one Embodiment of this invention. It is a whole schematic block diagram which shows the ultimate pressure detection state in the secondary detection of the perforation detection control of the fuel tank system which concerns on one Embodiment of this invention. It is a principal part block diagram which shows the ultimate pressure detection state in the secondary detection of the perforation detection control of the fuel tank system which concerns on one Embodiment of this invention. It is a flowchart which shows the perforation detection control of the fuel tank system which concerns on one Embodiment of this invention.

  A fuel tank system according to a first embodiment of the present invention will be described with reference to FIGS. In addition, each figure is typical and the illustration with a low relevance to the present invention is omitted. Further, a vehicle to which the fuel tank system of the present embodiment is applied is a hybrid vehicle (HV (Hybrid Vehicle)) or a plug-in hybrid vehicle (PHV (Plug-in Hybrid Vehicle)) having an engine and a motor as power sources. The case will be described.

(Constitution)
As shown in FIG. 1, the fuel tank system 10 according to the present embodiment has a fuel tank 12 in which fuel F is stored, a canister 14 in which fuel vapor in the fuel tank 12 is adsorbed, and an adsorbed in the canister 14. It basically includes an engine 16 to which fuel vapor is supplied and an ECU 18 that controls a pump, an electromagnetic valve, and the like based on signals from sensors and switches described later.

  The fuel tank 12 includes a fuel tank main body 20 in which the fuel F is stored, a filler pipe 22 extending obliquely upward from the fuel tank main body 20, and a cap 24 that closes a fuel inlet of the filler pipe 22. Yes.

  A fuel pump 26 is disposed inside the fuel tank body 20. A fuel supply pipe 28 that supplies fuel from the fuel pump 26 to the engine 16 passes through a lid 30 that closes an opening formed in the upper portion of the fuel tank main body 20, and is on the engine 16 side (an intake manifold 58 described later). ).

  A float valve 32 is disposed above the inside of the fuel tank body 20.

  On the other hand, the fuel inlet of the filler pipe 22 is disposed inside the lid 34 of the vehicle body, and at the time of fueling, the fuel nozzle 96 is inserted into the filler pipe 22 from which the cap 24 is removed from the opened lid 34. As a result, fuel is supplied to the fuel tank body 20 (see FIG. 3).

  The lid 34 is opened by operating a fuel switch 29 in the passenger compartment, and an operation signal for the fuel switch 29 is output to the ECU 18. The lid 34 is provided with a lid switch 36 that outputs the closure of the lid 34 to the ECU 18 as a switch signal.

  In the canister 14, a canister body 38 is vertically divided by a wall 40, and activated carbon 42 that serves as an adsorbent for fuel vapor is disposed on each canister 14.

  The introduction port 44 on the upstream side of the canister main body 38 is communicated with the fuel tank main body 20 (float valve 32) through the vapor pipe 46.

  The supply port 47 is in communication with an intake pipe 52 (described later) of the engine 16 and a purge pipe 48. On the purge pipe 48, an electromagnetic opening / closing valve 50 is provided for communicating or blocking the supply port 47 and the intake pipe 52. The intake pipe 52 communicated with the purge pipe 48 adjusts the flow rate of the air sucked through the air cleaner 54 by the throttle valve 56 and supplies the fuel mixture to the engine 16 through the intake manifold 58.

  An air release pipe 62 communicates with the ventilation port 60 on the downstream side of the canister body 38. The atmosphere release pipe 62 is an atmosphere port 64 whose end opposite to the ventilation port 60 communicates with the outside. An electromagnetic switching valve 66 is disposed on the atmosphere opening pipe 62. For convenience of explanation, in the atmosphere opening pipe 62, the canister 14 side (hereinafter referred to as “upstream side”) from the electromagnetic switching valve 66 is connected to the upstream atmosphere opening pipe 62 </ b> A and the atmosphere opening 64 side (hereinafter referred to as “ (Referred to as “downstream side”) is referred to as downstream-side air release pipe 62B. An air filter 68 is disposed on the atmosphere opening 64 side of the downstream atmosphere release pipe 62B.

  Further, a negative pressure action pipe 70 extending from the electromagnetic switching valve 66 and joining (communicating with) the downstream atmosphere release pipe 62B on the upstream side of the air filter 68 is formed. As will be described later, this negative pressure working tube 70 is communicated with or cut off from the upstream air release tube 62A by switching of the electromagnetic switching valve 66.

  Note that a key-off pump 72 that applies pressure to the upstream side is disposed in the negative pressure working tube 70.

  Further, it is branched from the upstream atmosphere release pipe 62A and merges upstream of the key-off pump 72 of the negative pressure working pipe 70 (upstream of the upstream atmosphere release pipe 62A and the negative pressure working pipe 70 from the key off pump 72). A reference tube 74 is formed. An electromagnetic switching valve 66 is also disposed on the reference pipe 74. For convenience of explanation, in the reference pipe 74, the upstream side of the electromagnetic switching valve 66 is referred to as an upstream reference pipe 74A, and the downstream side of the electromagnetic switching valve 66 is referred to as a downstream reference pipe 74B. By switching the electromagnetic switching valve 66, the upstream reference pipe 74A and the downstream reference pipe 74B are communicated or blocked.

  The upstream reference pipe 74 </ b> A is provided with a locally reduced reference portion 76 and a pressure sensor 78 on the downstream side of the reference portion 76. The pressure sensor 78 detects a differential pressure between the pressure inside the upstream reference pipe 74A and the atmospheric pressure.

  As shown in FIG. 2, the electromagnetic switching valve 66 includes a first communication passage 90 that allows the upstream air release pipe 62A and the downstream air release pipe 62B to communicate with the valve body 80, and the upstream air release pipe 62A that is negative. A second communication path 92 that communicates with the pressure application pipe 70 and a third communication path 94 that communicates the upstream reference pipe 74A and the downstream reference pipe 74B are formed. Each of the communication passages 90, 92, 94 is formed at a predetermined interval in the valve body 80 so that the four states described later can be switched. However, the first communication passage 90 is formed in an oblique direction so as to allow the upstream atmosphere release pipe 62A and the downstream atmosphere release pipe 62B to communicate with each other, and can be communicated both in the atmosphere open state and in the reference state as will be described later. As such, the diameter is double the diameter of the open air pipe 62.

  The electromagnetic switching valve 66 formed in this way selectively communicates the upstream side atmospheric open pipe 62A and the downstream side atmospheric open pipe 62B or the negative pressure working pipe 70, or blocks both of them. The upstream reference pipe 74A and the downstream reference pipe 74B are communicated or blocked.

  Specifically, the electromagnetic switching valve 66 drives the valve body 80 by a drive signal from the ECU 18 to switch the following four states. First, as shown in FIGS. 7 and 8, the first state shuts off the upstream atmosphere release pipe 62A, the downstream atmosphere release pipe 62B, and the negative pressure operation pipe 70, and the upstream side reference pipe 74A and the downstream side. This is a fully closed state in which the side reference tube 74B is shut off. Next, as shown in FIGS. 3 to 6, the second state is that the upstream side atmospheric open pipe 62 </ b> A and the downstream side atmospheric open pipe 62 </ b> B communicate with each other, and the upstream side reference pipe 74 </ b> A and the downstream side reference pipe 74 </ b> B It is in the open atmosphere state where As shown in FIG. 9, the third state is a reference state in which the upstream side atmospheric open pipe 62A and the downstream side atmospheric open pipe 62B are communicated, and the upstream side reference pipe 74A and the downstream side reference pipe 74B are communicated. It is. As shown in FIG. 10 and FIG. 11, the fourth state is a hole that connects the upstream air release pipe 62 </ b> A and the negative pressure working pipe 70 and blocks the upstream reference pipe 74 </ b> A and the downstream reference pipe 74 </ b> B. It is an open detection state.

  A relief valve 82 is provided between the upstream atmosphere release pipe 62A and the downstream atmosphere release pipe 62B. The electromagnetic switching valve 66 and the relief valve 82 are integrated as a module. Therefore, assembly is easy.

  Further, the oil supply switch 29, the lid switch 36, the electromagnetic switching valve 50, the electromagnetic switching valve 66, the key-off pump 72, and the pressure sensor 78 are connected to the ECU 18 through signal lines, respectively. The ECU 18 drives and controls the electromagnetic opening / closing valve 50, the electromagnetic switching valve 66, and the key-off pump 72 based on detection signals from the oil supply switch 29 and the lid switch 36. Further, the ECU 18 performs perforation detection based on the detection value of the pressure sensor 78.

(Function)
The operation (operation) of the fuel tank system 10 according to the present embodiment will be described. Hereinafter, control in each state will be described. In the initial state, the electromagnetic on-off valve 50 is closed and the electromagnetic switching valve 66 is fully closed.

  In each figure, the portion painted with the dot pattern indicates that the gas to be described is present or flowing. In this case, the fuel tank 12 and the filler pipe 22 are not painted with a dot pattern in order to prevent the figure from becoming complicated.

[When refueling]
First, refueling will be described with reference to FIGS. 3 and 4.

  As shown in FIG. 3, when an ON signal is input from the fuel supply switch 29 to the ECU 18 by operating the fuel supply switch 29 of the automobile, the ECU 18 determines that the fuel supply has started. As a result, the ECU 18 outputs an operation signal to the electromagnetic switching valve 66, and switches the electromagnetic switching valve 66 to open the atmosphere. Specifically, as shown in FIGS. 3 and 4, the upstream atmosphere release pipe 62 </ b> A and the downstream atmosphere release pipe 62 </ b> B are communicated, while the upstream reference pipe 74 </ b> A and the downstream reference pipe 74 </ b> B are blocked. State is maintained. Further, the electromagnetic on-off valve 50 is kept closed in the initial state.

  In this state, as shown in FIG. 3, the lid 34 is opened, the cap 24 is removed, and the fuel nozzle 96 is inserted into the filler pipe 22, whereby fuel is supplied to the fuel tank body 20. At this time, the canister 14 (ventilation port 60) and the atmosphere port 64 are communicated. Accordingly, the fuel vapor pressure in the fuel tank body 20 is increased, so that the fuel vapor is supplied from the vapor pipe 46 to the introduction port 44 of the canister 14. In the canister 14, after the fuel is adsorbed to the activated carbon 42, the gas from which the fuel has been removed from the fuel vapor is discharged to the outside through the electromagnetic switching valve 66 from the atmosphere port 64.

  The ECU 18 determines that refueling continues until the ON (blocking) signal is input from the lid switch 36 and maintains the state of the electromagnetic switching valve 66.

  As shown in FIG. 1, when the fuel injection port of the filler pipe 22 is closed by the cap 24 and the lid 34 is closed after the refueling is finished, an ON signal is output from the lid switch 36 to the ECU 18. When the ON signal is input from the lid switch 36, the ECU 18 determines that the lid 34 is closed and the refueling is finished.

  Thereafter, the ECU 18 outputs an operation signal to the electromagnetic switching valve 66, switches the electromagnetic switching valve 66, and returns it to the fully closed (initial) state. Thereby, the control at the time of refueling is complete | finished.

[During engine drive]
Next, control during engine drive travel will be described with reference to FIGS. 5 and 6. In the initial state, the electromagnetic on-off valve 50 is closed and the electromagnetic switching valve 66 is fully closed.

  First, the ECU 18 starts the engine drive running control when an engine drive signal is input from an engine ECU (not shown).

  As shown in FIG. 5, the ECU 18 outputs an operation signal to the electromagnetic opening / closing valve 50 to open the electromagnetic opening / closing valve 50. Also, as shown in FIGS. 5 and 6, an operation signal is output to the electromagnetic switching valve 66 to switch the electromagnetic switching valve 66 so that the atmosphere is open. That is, the upstream side atmospheric release pipe 62A and the downstream side atmospheric release pipe 62B are communicated with each other, and the upstream side reference pipe 74A and the downstream side reference pipe 74B are kept shut off.

  As a result, in the canister 14, the ventilation port 60 is communicated with the atmosphere port 64 and the supply port 47 is communicated with the intake pipe 52.

  Therefore, the air introduced through the atmosphere opening pipe 62 through the atmosphere opening pipe 62 ensures that the fuel adsorbed by the canister 14 becomes fuel vapor as fuel vapor to the intake pipe 52 via the purge pipe 48 in which the electromagnetic on-off valve 50 is opened. Supplied.

[During motor (engine not driven) travel]
Next, the engine non-drive running will be described with reference to FIGS.

  As shown in FIG. 7, when the ECU 18 recognizes that the vehicle is running only by the motor without driving the engine 16 based on a signal from the hybrid ECU (not shown), for example, the engine drive running When the motor is switched to traveling only by the motor, a closing signal is output from the ECU 18 to the electromagnetic opening / closing valve 50, and the electromagnetic opening / closing valve 50 is closed. Further, an operation signal is output from the ECU 18 to the electromagnetic switching valve 66, and the valve is fully closed. Specifically, as shown in FIGS. 7 and 8, the upstream side atmospheric open pipe 62A, the downstream side atmospheric open pipe 62B, and the negative pressure working pipe 70 are blocked, and the upstream side reference pipe 74A and the downstream side reference pipe are blocked. 74B is also blocked.

  As a result, the canister 14 is blocked from both the engine 16 (intake pipe 52) side and the atmosphere port 64 side. Therefore, it is possible to prevent the fuel adsorbed by the canister 14 from being discharged from the atmosphere port 64 as fuel vapor and discharged to the outside through the engine 16. In addition, since the entire fuel tank system 10 is closed as described above, the gas flow in the entire system is suppressed, so that the fuel vapor generated in the fuel tank body 20 is not transferred to the canister 14 when the engine 16 is not driven. It is possible to prevent the fuel vapor from being excessively adsorbed by the canister 14 by continuing to be supplied.

[When parking]
Next, the control at the time of parking is demonstrated with reference to FIG.7 and FIG.8. The ECU 18 detects that the vehicle is in a non-running state based on a signal from a hybrid ECU (not shown), and determines that the vehicle is parked when determining that refueling has not started. Also in this case, the ECU 18 closes the electromagnetic opening / closing valve 50 and switches the electromagnetic switching valve 66 to switch the upstream side atmospheric opening pipe 62A, the downstream side atmospheric opening pipe 62B, and the negative pressure working pipe 70 in the same manner as when the motor is running. And the upstream reference pipe 74A and the downstream reference pipe 74B are blocked. (The fuel tank system 10 is fully closed) (see FIG. 8).

  As a result, the canister 14 is blocked from both the engine 16 (intake pipe 52) side and the atmosphere port 64 side. Therefore, the fuel adsorbed on the canister 14 is prevented from being discharged to the outside as the fuel vapor from the atmosphere port 64. In addition, since the entire fuel tank system 10 is closed as described above, the gas flow in the entire system is suppressed, so that the fuel vapor generated in the fuel tank main body 20 is continuously supplied during parking so that the canister It is possible to prevent the fuel vapor from being excessively adsorbed by the fuel tank 14.

[When perforation is detected]
This perforation detection control will be described with reference to the flowcharts shown in FIGS.

  When the perforated detection control is performed, the ECU 18 detects that parking is started (travel stopped), and then a predetermined time has elapsed (Y in steps S100 and S102 in FIG. 12 (hereinafter “in FIG. 12”)). ))), And the primary detection of the perforated detection control is started.

  The primary detection detects the overall pressure of the fuel tank system 10. Specifically, as shown in FIG. 7, the ECU 18 first outputs an operation signal to the electromagnetic on-off valve 50 and the electromagnetic switching valve 66 to close the electromagnetic on-off valve 50 (step S104), and at the same time the electromagnetic switching valve 66. Is switched to a fully closed state (step S106). In this state, the ECU 18 detects the detection value of the pressure sensor 78 (the differential pressure between the atmospheric pressure P0 and the internal pressure Pt of the system (upstream reference pipe 74A)) (step S108). The ECU 18 compares this differential pressure with a preset threshold value (step S110). If the differential pressure is larger than the threshold value (N in step S110), the ECU 18 determines that there is no hole in the entire system, End the perforation detection control.

  On the other hand, if the detected value of the pressure sensor 78 is equal to or less than the threshold value (Y in step S110), it cannot be determined whether there is a perforation or other factors (external temperature, etc.). Perform secondary detection.

  First, an operation signal is output from the ECU 18 to the electromagnetic switching valve 66 to switch to the reference state (step S112). Specifically, as shown in FIG. 9, the upstream side atmospheric open pipe 62A and the downstream side atmospheric open pipe 62B communicate with each other, and the upstream side reference pipe 74A and the downstream side reference pipe 74B communicate with each other. In this state, the ECU 18 outputs a drive signal to the key-off pump 72. As a result, the key-off pump 72 is driven to apply a negative pressure to the reference pipe 74 (step S114).

  Here, since the atmosphere port 64 and the upstream reference pipe 74 </ b> A communicate with each other via the atmosphere release pipe 62, the gas flows from the upstream side to the downstream side of the reference pipe 74 by driving the key-off pump 72. Here, the ECU 18 stores the pressure value (referred to as “reference pressure”) detected by the pressure sensor 78 after a predetermined time has elapsed from the start of driving of the key-off pump 72 (step S116).

  The reference pressure can be regarded as a pressure detected by the pressure sensor 78 when a negative pressure is applied from the key-off pump 72 to the fuel tank system 10 in which the hole of the reference portion 76 has a hole diameter.

  Subsequently, the ECU 18 outputs an operation signal to the electromagnetic switching valve 66, and switches the electromagnetic switching valve 66 to the perforated detection state (step S118). That is, as shown in FIGS. 10 and 11, the upstream atmosphere opening pipe 62 </ b> A and the negative pressure working pipe 70 are communicated, and the upstream reference pipe 74 </ b> A and the downstream reference pipe 74 </ b> B are shut off.

  In this state, the ECU 18 outputs a drive signal to the key-off pump 72 and applies a negative pressure to the negative pressure operation tube 70 (step S120). As a result, a negative pressure acts on the entire fuel tank system 10 via the negative pressure operation pipe 70 and the upstream air release pipe 62A. After a predetermined time has elapsed since the key-off pump 72 was started, the ECU 18 detects a detection value (referred to as “attainment pressure”) of the pressure sensor 78 (step S122).

  The ECU 18 compares the reference pressure with the ultimate pressure (step S124). If the ultimate pressure is larger than the reference pressure (negative pressure is small) (Y in step S124), it is determined that there is a hole in the system, and for example, fuel is supplied to an instrument panel (hereinafter referred to as “instrument panel”). The perforation of the tank system 10 is displayed as a warning (step S126).

  On the other hand, if the ultimate pressure is equal to or lower than the reference pressure (N in step S124), the ECU 18 determines that there is no hole in the fuel tank system 10, ends the hole detection control, and sends an operation signal to the electromagnetic switching valve 66. Output and return to the initial state.

(effect)
In the fuel tank system 10, between the vent port 60 and the atmosphere port 64 of the canister 14, an atmosphere release pipe 62 that communicates the vent port 60 and the atmosphere port 64, a negative pressure operation pipe 70 provided with a key-off pump 72, and The reference unit 76 and the reference pipe 74 provided with the pressure sensor 78 are provided, and the electromagnetic switching valve 66 is used to switch between the fully closed state, the reference state, and the perforated detection state, and by driving the key-off pump 72, the canister 14 The perforation detection of the fuel tank system 10 can be accurately performed based on the detection value of the pressure sensor 78 disposed on the atmosphere port 64 side. That is, it is possible to accurately detect the perforation of the fuel tank system 10 with one pressure sensor 78.

  In particular, in the perforated detection control of the fuel tank system 10, the pressure is first set while the electromagnetic switching valve 66 is fully closed and the electromagnetic on-off valve 50 is closed, that is, the whole fuel tank system 10 is closed. Primary detection is performed by detecting (differential pressure with respect to atmospheric pressure) and comparing it with a threshold value. For this reason, when it is determined that there is no hole in the primary detection, there is an advantage that secondary detection (switching of the electromagnetic switching valve 66, driving of the key-off pump 72, etc.) becomes unnecessary.

  On the other hand, if it is not possible to determine that there is no hole by primary detection, secondary detection is performed. Specifically, by switching the electromagnetic switching valve 66 to the reference state and driving the key-off pump 72 to apply a negative pressure to the reference pipe 74, a hole having a hole diameter of the reference portion 76 is formed in the fuel tank system 10. A reference pressure corresponding to the formed case is detected. Subsequently, by switching the electromagnetic switching valve 66 to the perforated detection state and driving the key-off pump 72, negative pressure is applied to the entire fuel tank system 10 to detect the ultimate pressure. The ECU 18 determines whether or not there is a hole by comparing the ultimate pressure with the reference pressure.

  That is, if the differential pressure is below the threshold in the primary detection, it cannot be determined whether there is a perforation or an external condition (temperature), but the secondary detection detects the reference pressure and compares it with the ultimate pressure. Therefore, it is possible to detect a hole with high accuracy.

  The fuel tank system 10 is not provided with an electromagnetic opening / closing valve in the vapor pipe 46, but the electromagnetic switching valve 66 is fully closed and the electromagnetic opening / closing valve 50 is closed to seal the entire system (canister). 14 is cut off from the atmosphere port 64 and the intake pipe 52).

  Therefore, the fuel vapor is prevented from being discharged from the atmosphere port 64 or the engine 16 to the outside during parking or running of the motor (engine not driven). Further, by preventing the flow of gas from the fuel tank 12 to the canister 14, it is possible to prevent the fuel from adhering excessively to the canister 14.

  Further, since it is not necessary to provide an electromagnetic on-off valve in the vapor pipe 46, a pressure sensor for detecting the pressure in the fuel tank 12 for detecting a hole is not necessary, and the number of parts can be reduced.

  Further, the electromagnetic switching valve 66 has a function as a switching valve for selectively communicating the upstream side atmospheric open pipe 62A, the downstream side atmospheric open pipe 62B or the negative pressure working pipe 70, or blocking both, and an upstream reference. One valve body 80 achieves the function as an on-off valve for communicating or blocking the pipe 74A and the downstream reference pipe 74B. Therefore, the function as a switching valve and the function as an on-off valve can be achieved simultaneously by only driving the valve body 80 under the control of the ECU 18. That is, the control of the ECU 18 is simplified.

  In this embodiment, the example applied to a hybrid vehicle or a plug-in hybrid vehicle has been described. However, the present embodiment can also be applied to an automobile that runs only with a general gasoline engine or a diesel engine. In this case, the control at the time of traveling by only the motor is excluded.

  Further, the electromagnetic switching valve 66 has a function as a switching valve for selectively communicating the upstream side atmospheric open pipe 62A, the downstream side atmospheric open pipe 62B or the negative pressure working pipe 70, or blocking both, and an upstream reference. The function as an on-off valve for communicating or blocking the pipe 74A and the downstream reference pipe 74B is achieved by one valve body 80, but these may be configured as separate electromagnetic switching valves and electromagnetic on-off valves.

Further, although the ECU 18 determines the start of refueling based on the input of the ON signal from the refueling switch 29, it may be determined by an off (open) signal of the lid switch 36.
In the present embodiment, the key-off pump 72 has been described, but other pumps may be used as long as negative pressure can be similarly supplied by perforation detection.

DESCRIPTION OF SYMBOLS 10 Fuel tank system 12 Fuel tank 14 Canister 18 ECU (control part)
44 Introduction port 46 Vapor pipe (vapor passage)
47 Supply port 48 Purge pipe (purge passage)
50 Electromagnetic on-off valve (first on-off valve)
52 Intake pipe 60 Ventilation port 62 Open air pipe (first passage)
64 Air outlet (Atmospheric communication port)
66 Electromagnetic switching valve (switching valve, second on-off valve)
70 Negative pressure working tube (second passage)
72 Key-off pump (pump)
74 Reference pipe (third passage)
76 Reference section 78 Pressure sensor

Claims (3)

A fuel tank in which fuel is stored;
A canister for introducing and adsorbing fuel vapor from the fuel tank and supplying fuel vapor to the intake pipe; and
A vapor passage connecting the fuel tank and the introduction port of the canister;
A purge passage connecting the supply port of the canister and the intake pipe;
A first on-off valve provided in the purge passage and communicating or blocking the purge passage;
A first passage for communicating the vent port of the canister and the air communication opening opened to the outside;
A second passage branched from the middle of the first passage, and joined to the first passage on the atmosphere communication port side than a branch position in the first passage;
A pump provided in the second passage for applying pressure to the canister side;
Provided at the branching position, selectively communicates the canister side of the first passage with the atmosphere communication port side of the first passage or the second passage, or blocks the canister side of the first passage. A switching valve to
A third passage that branches from the canister side of the switching valve of the first passage and merges with the second passage on the canister side of the pump of the second passage;
A second on-off valve provided in the third passage, for communicating or blocking the canister side and the atmosphere communication side of the third passage;
A pressure sensor that is provided closer to the canister than the second on-off valve in the third passage, and detects a pressure in the third passage;
A reference portion provided on the canister side with respect to the pressure sensor in the third passage, wherein the third passage is partially reduced in diameter;
A control unit that controls the driving of the switching valve, the first on-off valve, the second on-off valve, and the pump, and that determines perforation of the system based on a detection value of the pressure sensor;
A fuel tank system comprising. The control unit switches the switching valve to block the canister side of the first passage from the atmosphere communication port side of the first passage and the second passage, and the first opening / closing valve and the second opening / closing When the valve is closed and the purge passage and the third passage are shut off, the differential pressure between the pressure value detected by the pressure sensor and the atmospheric pressure is compared with a preset threshold value, and the differential pressure Primary detection that determines that there is no perforation when is greater than the threshold;
When the differential pressure is less than or equal to the threshold value in the primary detection, the switching valve is switched to connect the canister side of the first passage and the atmosphere communication side of the first passage, and the second on-off valve In a state where the third passage is communicated by switching, the pump is driven to apply a negative pressure to the third passage and the reference pressure detected by the pressure sensor and the switching valve are switched to switch the first passage. The first passage is connected to the canister side and the second passage, and with the purge passage and the third passage shut off, the pump is driven to apply a negative pressure to the second passage. Secondary detection comparing the ultimate pressure detected by the sensor and determining that the system has a hole when the ultimate pressure is greater than the reference pressure;
The fuel tank system according to claim 1, wherein:   The fuel tank system according to claim 1 or 2, wherein the switching valve and the second on-off valve are integrated with each other.