Flow control valve and fuel vapor treatment device

Abstract

To inhibit increase of a flow rate in a part of a small opening area in which a lift amount is smaller than or equivalent to a certain lift amount.SOLUTION: A flow control valve 38 includes: a casing 52 having a fluid passage 65; a valve seat 67 having a valve hole 68 provided at the fluid passage 65; an electric motor 54 installed at the casing 52; and a valve body 58 which opens or closes the valve seat 67 by the electric motor 54 controlling the stroke in an axial direction through a feed screw mechanism 83. The valve body 58 has a straight protruding cylinder part 89 located in the valve hole 68 in a small opening area in which a lift amount is smaller than or equivalent to a certain lift amount.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a flow control valve and an evaporated fuel treatment device. [Background technology]

[0002] Conventionally, there is an evaporated fuel processing device that adsorbs evaporated fuel in a fuel tank of a vehicle equipped with an internal combustion engine into a canister and purges the adsorbed evaporated fuel into the internal combustion engine (see Patent Document 1). The evaporated fuel processing device includes a vapor passage that connects the fuel tank and the canister, a shutoff valve that opens and closes the vapor passage, and a float valve that prevents fuel in the fuel tank from flowing into the vapor passage.

[0003] The shutoff valve includes a casing with a fluid passage, a valve seat with a valve hole provided in the fluid passage, an electric motor installed in the casing, and a valve body that opens and closes the valve seat by controlling the stroke in the axial direction by the electric motor via a feed screw mechanism. Since the opening and closing of the valve body is only stroke controlled, the flow rate (passage area) changes proportionally to the lift amount (opening) of the valve body, resulting in a linear characteristic. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5996799 Summary of the Invention [Problem to be solved by the invention]

[0005] When refueling, if the fuel tank is sealed with the shut-off valve closed and the internal pressure of the fuel tank is high, and the fuel tank's filler cap is opened, the fuel vapor that has accumulated in the fuel tank will be released into the atmosphere through the filler opening. Therefore, before opening the fuel cap, the shut-off valve is opened to reduce the internal pressure of the fuel tank (so-called pressure relief). If the shut-off valve is opened suddenly at this time, the dynamic pressure generated by the fuel vapor in the fuel tank flowing out forcefully into the vapor passage may cause the float of the float valve to stick (close), making it impossible to relieve pressure.

[0006] The problem to be solved by the technology disclosed in this specification is to suppress an increase in the flow rate in a part of the small opening range below a certain lift amount. [Means for solving the problem]

[0007] In order to solve the above problems, the technique disclosed in this specification takes the following measures.

[0008] The first means is a flow control valve comprising: a casing having a fluid passage; a valve seat having a valve hole provided in the fluid passage; an electric motor installed in the casing; and a valve body that opens and closes the valve seat by being stroke-controlled in the axial direction by the electric motor via a feed screw mechanism, wherein the valve body has a straight protrusion that is located within the valve hole in a small opening region below a certain lift amount.

[0009] According to the first aspect, in the small opening region where the lift amount is equal to or less than a certain amount, the protruding portion of the valve body is located inside the valve hole, so that an increase in the flow rate can be suppressed in a part of the small opening region, and thus the controllability of the flow rate can be improved.

[0010] The second means is a flow control valve of the first means, wherein the valve body is provided with a sealing member having an annular sealing portion that elastically seals between the valve body and the valve seat in a fully closed state, and an expanded space is formed in the fully closed state that is surrounded by the valve seat, the protrusion, and the sealing portion and communicates with the gap between the valve hole and the protrusion.

[0011] According to the second means, an expanded space is formed that communicates with the gap between the valve hole and the protruding portion in the fully closed state, which clarifies the switch from flow rate control by the gap between the valve seat and the seal portion of the seal member to flow rate control by the gap between the valve hole and the protruding portion, thereby suppressing deviation in flow rate, compared to the case where an expanded space is not formed.

[0012] The third means is a flow control valve of the first or second means, comprising a guide member moved axially by the feed screw mechanism, a connecting mechanism which connects the guide member to the valve body when the valve body is open and which disconnects the guide member from the valve body in the fully closed state, and a biasing means which biases the valve body and the guide member in opposite directions.

[0013] According to the third aspect, the increase or decrease in the distance between the electric motor and the valve seat caused by the dimensional change of the casing due to temperature change can be absorbed by the change in the amount of movement between the valve body and the guide member, thereby making it possible to suppress the occurrence of problems such as a decrease in sealing force in the fully closed state and malfunction of the valve body.

[0014] The fourth means is an evaporated fuel treatment device that adsorbs evaporated fuel in a fuel tank of a vehicle equipped with an internal combustion engine into a canister and purges the adsorbed evaporated fuel into the internal combustion engine, the evaporated fuel treatment device comprising a vapor passage connecting the fuel tank and the canister, a shutoff valve that opens and closes the vapor passage, and a float valve that prevents fuel in the fuel tank from flowing into the vapor passage, and the shutoff valve is a flow control valve of any one of the first to third means.

[0015] According to a fourth aspect, it is possible to provide an evaporated fuel processing device having a flow control valve as a shutoff valve that can suppress an increase in the flow rate in a part of the small opening range below a certain lift amount. As a result, even if the shutoff valve is opened before the fuel cap is opened during refueling, it is possible to suppress the evaporated fuel in the fuel tank from flowing out forcefully into the vapor passage. Therefore, the float valve can be released without being closed by dynamic pressure. Effect of the Invention

[0016] According to the technology disclosed in this specification, it is possible to suppress an increase in the flow rate in a part of the small opening range below a certain lift amount. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram showing a configuration of an evaporated fuel treatment device according to an embodiment; [Diagram 2] FIG. 4 is a cross-sectional view showing a flow control valve in a closed state. [Diagram 3] 6 is a cross-sectional view showing the function of a protruding cylindrical portion of the valve body. FIG. [Figure 4] FIG. 4 is a cross-sectional view showing a flow control valve in an open state. [Diagram 5] FIG. 4 is a cross-sectional view showing an expanded space portion. [Figure 6] FIG. 4 is a characteristic diagram showing the relationship between the lift amount of a valve body and a flow rate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment for carrying out the technology disclosed in this specification will be described with reference to the drawings. The flow control valve of this embodiment is provided as a shutoff valve in an evaporated fuel treatment device mounted on a vehicle such as an automobile equipped with an internal combustion engine. Therefore, after describing the evaporated fuel treatment device, the flow control valve as a shutoff valve will be described.

[0019] (Fuel Evaporation Treatment Device) Fig. 1 is a configuration diagram showing an evaporated fuel processing device. As shown in Fig. 1, an evaporated fuel processing device 12 is provided in an engine system 10 of a vehicle such as an automobile. The engine system 10 includes an engine 14 and a fuel tank 15 that stores fuel to be supplied to the engine 14. An inlet pipe 16 is provided in the fuel tank 15. The inlet pipe 16 is a pipe that introduces fuel into the fuel tank 15, and a fuel filler cap 17 is detachably attached to a filler port at the upper end of the inlet pipe 16. A breather pipe 18 connects the upper end of the inlet pipe 16 to an air space in the fuel tank 15.

[0020] A fuel supply device 19 is provided in the fuel tank 15. The fuel supply device 19 includes a fuel pump 20 that draws in fuel in the fuel tank 15, pressurizes it, and discharges it, a sender gauge 21 that detects the fuel level, and a tank internal pressure sensor 22 that detects the tank internal pressure as a relative pressure to atmospheric pressure. The fuel pump 20 pumps up from the fuel tank 15 through a fuel supply passage 24 and supplies it to the engine 14, more specifically, to a delivery pipe 26 equipped with injectors 25 corresponding to each combustion chamber, and then the fuel is injected from each injector 25 into an intake passage 27. The intake passage 27 is provided with an air cleaner 28, an air flow meter 29, a throttle valve 30, and the like.

[0021] The evaporated fuel processing device 12 includes a vapor passage 31, a purge passage 32, and a canister 34. The vapor passage 31 connects the gas space of the fuel tank 15 to the canister 34. The purge passage 32 connects the canister 34 to the intake passage 27. The canister 34 is filled with activated carbon (not shown) as an adsorbent. The evaporated fuel in the fuel tank 15 is adsorbed by the adsorbent (activated carbon) in the canister 34 via the vapor passage 31.

[0022] An ORVR valve (On Board Refueling Vapor Recovery valve) 35 and a cut-off valve 36 are provided at the upstream end of the vapor passage 31. The ORVR valve 35 and the cut-off valve 36 are disposed in a vapor space in the fuel tank 15.

[0023] The ORVR valve 35 is a full tank limiting valve having a float 35a that opens and closes due to the buoyancy of the fuel. When the fuel level in the fuel tank 15 reaches full tank, the float 35a closes the passage leading to the vapor passage 31, thereby preventing the fuel in the fuel tank 15 from leaking into the vapor passage 31. When the ORVR valve 35 closes during refueling, the auto-stop mechanism of the fuel gun is activated to stop refueling.

[0024] The cut-off valve 36 has a float 36a that opens and closes due to the buoyancy of the fuel. When the fuel tank 15 tilts at a predetermined angle or more and the fuel level reaches a predetermined level, such as when the vehicle rolls over, the float 36a of the cut-off valve 36 closes the passage leading to the vapor passage 31, thereby preventing the fuel in the fuel tank 15 from flowing out into the vapor passage 31. The cut-off valve 36 is disposed at a higher position than the ORVR valve 35. The ORVR valve 35 and the cut-off valve 36 correspond to the "float valve" as referred to in this specification.

[0025] A shutoff valve 38 is provided in the vapor passage 31. The shutoff valve 38 is, for example, an electric valve equipped with a stepping motor and capable of adjusting the lift amount of the valve body by controlling the stroke of the valve body. The shutoff valve 38 will be described later.

[0026] A purge valve 40 is provided in the purge passage 32. For example, an electric valve equipped with a stepping motor and capable of adjusting the opening amount by controlling the stroke of a valve body is used for the purge valve 40. Alternatively, a solenoid valve equipped with an electromagnetic solenoid and closing when de-energized and opening when energized may be used for the purge valve 40.

[0027] An air passage 42 is connected to the canister 34 via a changeover valve 41. The changeover valve 41 is provided with an electromagnetic solenoid, and is a solenoid valve that is closed when not energized and opens when energized. The air passage 42 is open to the atmosphere. An air filter 43 is installed midway through the air passage 42.

[0028] The shutoff valve 38, the purge valve 40 and the changeover valve 41 are each controlled to open and close by an engine control unit (hereinafter referred to as "ECU") 45. The tank internal pressure sensor 22, a lid switch 46, a lid opener 47, a display device 49 and the like are connected to the ECU 45. The lid opener 47 is a locking mechanism for a lid 48 that is provided on the vehicle body side and covers the fuel filler opening. A manual lid opening and closing device (not shown) for manually opening and closing the lid 48 is connected to the lid opener 47.

[0029] The lid switch 46 outputs a signal to the ECU 45 to unlock the lid 48. The lid opener 47 unlocks the lid 48 when a signal to unlock the lid is supplied from the ECU 45 or when an opening operation is performed on the lid manual opening and closing device. The ECU 45 corresponds to the "control device" in this specification.

[0030] (Operation of the evaporated fuel treatment device 12) (1) While the vehicle is parked While the vehicle is parked, the shutoff valve 38, the purge valve 40, and the switching valve 41 are all maintained in a closed state. Since the shutoff valve 38 is in a closed state, the evaporated fuel in the fuel tank 15 does not flow into the canister 34. In addition, the air in the canister 34 does not flow into the fuel tank 15.

[0031] (2) While the vehicle is moving When a predetermined purge condition is satisfied while the vehicle is running, the ECU 45 executes control to purge the evaporated fuel adsorbed in the canister 34. In this control, the purge valve 40 is controlled while the switching valve 41 is kept open. When the purge valve 40 is opened, the intake negative pressure of the engine 14 acts on the inside of the canister 34 via the purge passage 32. As a result, the evaporated fuel in the canister 34 is purged into the intake passage 27 together with air drawn in from the atmospheric passage 42, and is burned in the engine 14. In addition, the ECU 45 opens the shutoff valve 38 only during the purging of the evaporated fuel. This maintains the tank internal pressure of the fuel tank 15 at a value close to atmospheric pressure.

[0032] (3) Refueling When the lid switch 46 is operated to refuel while the vehicle is stopped, the ECU 45 opens the shutoff valve 38. At this time, if the internal tank pressure of the fuel tank 15 is higher than atmospheric pressure, the evaporated fuel in the fuel tank 15 passes through the vapor passage 31 and is adsorbed by the adsorbent in the canister 34 at the same time as the shutoff valve 38 opens. This prevents the evaporated fuel from being released into the atmosphere. Accordingly, the internal tank pressure of the fuel tank 15 drops to a value close to atmospheric pressure.

[0033] When the tank internal pressure of the fuel tank 15 drops to a value close to atmospheric pressure, the ECU 45 outputs a signal to the lid opener 47 to unlock the lid 48. The lid opener 47 receives the signal and unlocks the lid 48, thereby enabling the lid 48 to be opened. Then, with the lid 48 open and the fuel filler cap 17 open, fuel is filled into the fuel tank 15. The ECU 45 also keeps the shutoff valve 38 open until the end of refueling (specifically, until the lid 48 is closed). Therefore, as refueling occurs, evaporated fuel in the fuel tank 15 passes through the vapor passage 31 and is adsorbed by the adsorbent in the canister 34.

[0034] (Flow control valve as shutoff valve 38) A flow control valve 38 (with the same reference numeral as the shutoff valve 38) used as the shutoff valve 38 will be described. Fig. 2 is a cross-sectional view showing the flow control valve in a closed state. The up, down, left and right directions of the flow control valve 38 are determined based on Fig. 2, but the arrangement direction of the flow control valve 38 is not specified.

[0035] As shown in Fig. 2, the flow control valve 38 includes a casing 52, an electric motor 54, a guide member 56, a valve body 58, and a valve spring 60. A cylindrical valve chamber 62 with a bottom is formed in the casing 52, with an axis that is a straight line extending in the vertical direction. A hollow cylindrical inlet passage 63 extending downward is formed concentrically in the center of the lower surface of the valve chamber 62. The inlet passage 63 is connected to a passage on the upstream side (fuel tank 15 side) of the vapor passage 31 (see Fig. 1).

[0036] A hollow cylindrical outflow passage 64 extending laterally (to the right) is formed in the lower part of the inner circumferential surface of the valve chamber 62. The outflow passage 64 is connected to a passage on the downstream side (canister 34 side) of the vapor passage 31. The valve chamber 62, the inflow passage 63, and the outflow passage 64 form an inverted L-shaped fluid passage 65. Thus, the casing 52 has the fluid passage 65.

[0037] A valve seat 67 is formed by the rim of the upper opening of the inflow passage 63. The upper opening of the inflow passage 63 is a circular valve hole 68 of the valve seat 67. The upper surface of the valve seat 67 is formed on a plane perpendicular to the axis of the valve chamber 62. An annular spring receiving groove 69 is formed on the outer periphery of the lower surface of the valve chamber 62.

[0038] The electric motor 54 is a stepping motor, and is drive-controlled by the ECU 45 (see FIG. 1). The electric motor 54 has a motor body 71 and an output shaft 72 that protrudes downward from the motor body 71 and is rotatable in both forward and reverse directions. The motor body 71 is disposed on the upper part of the casing 52. The output shaft 72 is disposed concentrically within the valve chamber 62 of the casing 52. A male thread portion 73 is formed on the outer circumferential surface of the output shaft 72.

[0039] The guide member 56 concentrically comprises a cylindrical tube wall portion 75, an upper wall portion 76 closing the upper end opening of the tube wall portion 75, and a bottomed cylindrical tube shaft portion 79 formed in the center of the upper wall portion 76. The vertical center portion of the tube shaft portion 79 is connected to the upper wall portion 76. A female thread portion 80 is formed on the inner circumferential surface of the tube shaft portion 79. An annular protruding wall portion 75a protruding radially outward is formed at the upper end portion of the tube wall portion 75.

[0040] The guide member 56 is disposed within the valve chamber 62 of the casing 52 so as to be movable in the axial direction (up and down) while being prevented from rotating in the axial direction by anti-rotation means (not shown). The male thread portion 73 of the output shaft 72 and the female thread portion 80 of the cylindrical shaft portion 79 are screwed together. Therefore, the guide member 56 is caused to perform a linear reciprocating motion, i.e., to rise and fall, in the axial direction (up and down) based on the forward and reverse rotation of the output shaft 72 of the electric motor 54. The male thread portion 73 and the female thread portion 80 form a feed screw mechanism 83.

[0041] An auxiliary spring 85 made of a coil spring is interposed between the protruding wall portion 75a of the cylindrical wall portion 75 of the guide member 56 and the spring receiving groove 69 of the casing 52. The auxiliary spring 85 constantly biases the guide member 56 upward, thereby preventing backlash of the feed screw mechanism 83.

[0042] The valve body 58 has a cylindrical tubular portion 87 and a lower wall portion 88 that is concentric with the cylindrical portion 87 and closes the lower end opening of the cylindrical portion 87. The lower wall portion 88 has an outer diameter larger than the outer diameter of the cylindrical portion 87. The valve body 58 has a straight protruding tubular portion 89.

[0043] The protruding tubular portion 89 protrudes concentrically from the lower surface of the lower wall portion 88. The protruding tubular portion 89 is formed in a cylindrical shape having an outer diameter smaller than the inner diameter of the valve hole 68 of the valve seat 67. A tapered portion 89a is formed at the lower end (tip portion) of the protruding tubular portion 89. The outer peripheral surface of the protruding tubular portion 89 excluding the tapered portion 89a is formed as a tapered surface whose diameter becomes slightly smaller from the upper end toward the lower portion. A plurality of (e.g., two) communication holes 89b are formed at the upper end (base end) of the protruding tubular portion 89, penetrating in the radial direction. The protruding tubular portion 89 corresponds to the "protruding portion" as referred to in this specification.

[0044] A seal member 90 made of a disc-shaped rubber-like elastic material is provided on the lower surface of the lower wall portion 88. The seal member 90 has a seal portion 90a, an inner plate portion 90b, and a connection portion 90c. The seal portion 90a is formed in an annular shape covering the radially outer region of the protruding tube portion 89 on the lower surface of the lower wall portion 88. The seal portion 90a is formed in an inverted mountain shape in cross section. The inner plate portion 90b is formed in a plate shape covering the radially inner region of the protruding tube portion 89 on the lower surface of the lower wall portion 88. The connection portion 90c is formed so as to fill the communication hole 89b of the protruding tube portion 89. The upper portion of the seal portion 90a and the inner plate portion 90b are connected by the connection portion 90c.

[0045] The valve body 58 is arranged concentrically within the cylindrical wall portion 75 of the guide member 56 so as to be vertically movable while being prevented from rotating about the axis. As a result, the valve body 58 is arranged so as to be able to open and close the valve seat 67. In addition, the protruding cylindrical portion 89 of the valve body 58 is arranged so as to be able to be inserted and removed into the valve hole 68 of the valve seat 67. The seal portion 90a of the seal member 90 is arranged so as to be able to abut (seat) against the valve seat 67 of the casing 52.

[0046] 5, in a closed valve state where the valve body 58 is seated on the valve seat 67, an expanded space 93 is formed in a portion surrounded by the valve seat 67, the protruding tubular portion 89, and the seal portion 90a. The expanded space 93 communicates with a cylindrical gap 102 formed between the inner circumferential surface of the valve hole 68 and the outer circumferential surface of the protruding tubular portion 89. The gap 102 serves as an inlet for the fluid leading to the expanded space 93. The expanded space 93 has a cross-sectional area larger than the cross-sectional area (passage area) of the gap 102.

[0047] 2, the valve spring 60 is a coil spring, and is interposed between the upper wall portion 76 of the guide member 56 and the lower wall portion 88 of the valve body 58. The valve spring 60 biases the guide member 56 and the valve body 58 in opposite directions. The valve spring 60 corresponds to the "biasing means" in this specification.

[0048] Between the guide member 56 and the valve body 58, a connecting mechanism 95 is provided to connect the guide member 56 and the valve body 58 so that the two members 56 and 58 can be moved within a predetermined range in the vertical direction. The connecting mechanism 95 is composed of a locking protrusion 75b protruding from the inner peripheral surface of the cylindrical wall portion 75 of the guide member 56 and an engagement protrusion 87a protruding from the outer peripheral surface of the cylindrical portion 87 of the valve body 58. The engagement protrusion 87a is disposed above the locking protrusion 75b. When the valve body 58 is opened, the locking protrusion 75b and the engagement protrusion 87a are engaged with each other by the urging force of the valve spring 60, so that the guide member 56 and the valve body 58 are integrally connected. In addition, in the fully closed state, the connecting mechanism 95 releases the connection between the guide member 56 and the valve body 58 by separating the locking protrusion 75b and the engagement protrusion 87a against the urging force of the valve spring 60. Note that a plurality of sets (for example, four sets) of the connecting mechanism 95 are disposed at equal intervals in the circumferential direction.

[0049] (Flow control valve 38 closed state) When the flow control valve 38 is in a closed state (see FIG. 2), the valve body 58 is held seated on the valve seat 67 by the biasing force of the valve spring 60. The gap between the valve body 58 and the valve seat 67 of the casing 52 is elastically sealed by a seal portion 90a of a seal member 90. The protruding tubular portion 89 of the valve body 58 is positioned within the valve hole 68 of the valve seat 67. The locking projection 75b and the engaging projection 87a of the connecting mechanism 95 are spaced apart.

[0050] Even if the electric motor 54 is de-energized (OFF) in the valve-closed state, the valve-closed state can be maintained by the detent torque of the electric motor 54, the lead angle of the feed screw mechanism 83, and the like. In addition, the casing 52 may change in dimensions in the vertical direction due to temperature changes. For example, when the casing 52 expands, the distance (spacing) between the electric motor 54 and the valve seat 67 increases, and the guide member 56 moves upward, but the valve body 58 does not move. This makes it possible to maintain the sealing force between the valve body 58 and the valve seat 67. In addition, when the casing 52 contracts, the distance (spacing) between the electric motor 54 and the valve seat 67 decreases, and the guide member 56 moves downward, but the valve body 58 does not move. This prevents the valve body 58 from being strained, and does not cause malfunction.

[0051] (When the flow control valve 38 is opened) When the electric motor 54 is operated by the ECU 45 to open the flow control valve 38 in a closed state, the guide member 56 is raised via the feed screw mechanism 83. In response to this, the valve spring 60 is expanded by its elastic restoring force. Furthermore, after the engaging projection 87a comes into contact with the locking projection 75b of the connecting mechanism 95, the guide member 56 and the valve body 58 are raised together. That is, the electric motor 54 controls the stroke in the axial direction via the feed screw mechanism 83. In response to this, the seal portion 90a of the seal member 90 of the valve body 58 separates from the valve seat 67.

[0052] Then, as shown in FIG. 3, a gap 101 is formed between the valve seat 67 and the seal portion 90a. The gap 101 communicates with a cylindrical gap 102 formed between the valve hole 68 and the protruding tube portion 89 via an expanded space portion 93. In addition, with an increase in the lift amount of the valve body 58, the gap 101 functions as a first throttle portion 101 (with the same reference numeral as the gap 101) until the passage area of ​​the gap 101 exceeds the passage area of ​​the gap 102. As a result, the passage area increases in proportion to the increase in the lift amount of the valve body 58. That is, the flow rate of the fluid flowing through the fluid passage 65 increases. The lift amount of the valve body 58 corresponds to the number of steps of the electric motor 54.

[0053] Next, when the passage area of ​​gap 101 exceeds the passage area of ​​gap 102 with an increase in the lift amount of valve body 58, gap 102 functions as a second throttling portion 102 (with the same reference numeral as gap 102). This suppresses an increase in the passage area even if the lift amount of valve body 58 increases. In other words, an increase in the flow rate of the fluid flowing through fluid passage 65 is suppressed. The period from the valve closed state until the protruding tubular portion 89 of valve body 58 comes out of the valve hole 68 of the valve seat 67 corresponds to the "small opening region below a certain lift amount" as used in this specification.

[0054] Next, when the lower end of the outer circumferential surface of the protruding tubular portion 89 excluding the tapered portion 89a of the valve body 58 moves to a position higher than the upper end of the valve hole 68 of the valve seat 67, the passage area increases in proportion to the increase in the lift amount of the valve body 58. In other words, the flow rate of the fluid flowing through the fluid passage 65 increases. Finally, the valve is fully open (see FIG. 4).

[0055] (Flow control valve 38 open state) As shown in FIG. 4, when the flow control valve 38 is in an open state, even if the power supply to the electric motor 54 is turned off, the open state can be maintained by the detent torque of the electric motor 54, the lead angle of the feed screw mechanism 83, etc.

[0056] (When the flow control valve 38 is closed) When the electric motor 54 is operated to close the valve by the ECU 45 while the flow control valve 38 is in the open state (see FIG. 4), the valve body 58 is lowered together with the guide member 56, which is the opposite of the valve opening operation. Then, the seal portion 90a of the seal member 90 seats on the valve seat 67, thereby restricting the downward movement of the valve body 58. Next, as the guide member 56 is lowered, the locking projection 75b of the connecting mechanism 95 moves away from the engaging projection 87a. Then, before the cylindrical wall portion 75 of the guide member 56 comes into contact with the valve seat 67, the valve closing operation of the electric motor 54 is stopped by the ECU 45 (see FIG. 2).

[0057] (Characteristics of flow control valve 38) FIG. 6 is a characteristic diagram showing the relationship between the lift amount of the valve body 58 and the flow rate. In FIG. 6, the horizontal axis indicates the lift amount, and the vertical axis indicates the flow rate. Lift amount L0-L1 is the period from when the valve body 58 starts to rise from the closed state to when the seal portion 90a of the seal member 90 separates from the valve seat 67. Lift amount L1-L2 is the period during which the first throttling portion 101 acts. Lift amount L2-L3 is the period during which the second throttling portion 102 acts. Lift amount L0-L3 corresponds to the small opening region, and lift amount L2-L3 is the period during which the increase in the flow rate is suppressed, and corresponds to a part of the small opening region.

[0058] (Advantages of the embodiment) According to the flow control valve 38, in a small opening region below a certain lift amount, the protruding tubular portion 89 of the valve body 58 is located inside the valve hole 68, so that an increase in the flow rate can be suppressed in a part of the small opening region. As a result, the controllability of the flow rate can be improved.

[0059] In addition, an expanded space 93 is formed that communicates with a gap 102 between the valve hole 68 and the protruding tubular portion 89 in the fully closed state. This clarifies the switch from flow rate control by the gap 101 between the valve seat 67 and the seal portion 90a of the seal member 90 to flow rate control by the gap 102 between the valve hole 68 and the protruding tubular portion 89, compared to a case in which the expanded space 93 is not formed, and makes it possible to suppress deviations in the flow rate.

[0060] Also provided are a guide member 56 that is moved axially by a feed screw mechanism 83, a connecting mechanism 95 that connects the guide member 56 and the valve body 58 when the valve body 58 is open and disconnects the guide member 56 and the valve body 58 in a fully closed state, and a valve spring 60 that biases the valve body 58 and the guide member 56 in opposite directions. This makes it possible to absorb an increase or decrease in the distance between the electric motor 54 and the valve seat 67 caused by a dimensional change in the casing 52 due to a temperature change by changing the amount of movement between the valve body 58 and the guide member 56. This makes it possible to suppress the occurrence of problems such as a decrease in sealing force in the fully closed state and malfunction of the valve body 58.

[0061] The evaporated fuel processing device 12 also includes a flow control valve 38 as the shutoff valve 38. Therefore, it is possible to provide the evaporated fuel processing device 12 including, as the shutoff valve 38, a flow control valve 38 that can suppress an increase in the flow rate in a portion of a small opening range below a certain lift amount. As a result, even if the shutoff valve 38 is opened before the fuel cap 17 is opened during refueling, it is possible to suppress the evaporated fuel in the fuel tank 15 from flowing out forcefully into the vapor passage 31. Therefore, pressure can be released without the ORVR valve 35 and / or the cutoff valve 36 being closed by dynamic pressure.

[0062] [Other embodiments] The technology disclosed in this specification is not limited to the above-mentioned embodiment, and can be embodied in various other forms. For example, the flow control valve 38 may be applied to an application other than the shutoff valve 38 of the evaporated fuel processing device 12. The guide member 56 may be omitted. The electric motor 54 may include an output shaft 72 that moves in the axial direction by incorporating a feed screw mechanism 83. In this case, the guide member 56 may be integrally connected to the output shaft 72. The protruding portion is not limited to the protruding tubular portion 89, and may be formed in a solid shape. The protruding tubular portion 89 is not limited to a cylindrical shape, and may be a square tube shape. The tapered portion 89a of the protruding tubular portion 89 may be omitted. [Explanation of symbols]

[0063] 12 Fuel vapor treatment device 14 Engine (internal combustion engine) 15 Fuel Tank 31 Vapor passage 34 Canister 35 ORVR valve (float valve) 36 Cut-off valve (float valve) 38 Flow control valve (shutoff valve) 45 ECU (engine control unit, control unit) 52 Casing 54 Electric Motor 56 Guide member 58 Valve body 60 Valve spring (biasing means) 65 Fluid passage 67 Valve seat 68 Valve hole 83 Lead screw mechanism 89 Projecting cylinder part (projecting part) 90 Sealing material 90a Seal part 93 Vast space part 95 Connection mechanism 102 Gap (gap between valve hole and protrusion)

Claims

1. a casing having a fluid passage; a valve seat having a valve hole provided in the fluid passage; an electric motor installed in the casing; a valve body that opens and closes the valve seat by being stroke-controlled in an axial direction by the electric motor via a feed screw mechanism; A flow control valve comprising: the valve body has a straight protrusion that is located within the valve hole in a small opening region that is equal to or smaller than a certain lift amount, the valve body includes a seal member having an annular seal portion that elastically seals between the valve body and the valve seat in a fully closed state, a flow control valve in which, in the fully closed state, an expanded space is formed which is surrounded by the valve seat, the protrusion, and the seal portion and which communicates with a gap between the valve hole and the protrusion.

2. 2. The flow control valve according to claim 1, A guide member that is moved axially by the feed screw mechanism; a connecting mechanism that connects the guide member to the valve body when the valve body is open and that disconnects the guide member from the valve body when the valve body is fully closed; a biasing means for biasing the valve body and the guide member in opposite directions; A flow control valve comprising:

3. An evaporated fuel treatment device that adsorbs evaporated fuel in a fuel tank of a vehicle equipped with an internal combustion engine into a canister and purges the adsorbed evaporated fuel into the internal combustion engine, a vapor passage connecting the fuel tank and the canister; a shutoff valve for opening and closing the vapor passage; a float valve that prevents fuel in the fuel tank from flowing out into the vapor passage; Equipped with 3. An evaporated fuel treatment apparatus comprising the flow control valve according to claim 1 or 2 as the shutoff valve.

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