Fluid control electromagnetic valve

A fluid control electromagnetic valve includes a fixed core, a movable valving element, a resin body, a valve seat member, a first sealing member, and a second sealing member. The valve seat member is formed from a material having a smaller linear expansion coefficient than the resin body. The first sealing member is accommodated in the resin body in an elastic compression state to seal a fluid passage and is positioned around the fixed core. The second sealing member is accommodated in the resin body in an elastic compression state to seal the fluid passage. The valve seat member is clamped between the second sealing member and the first sealing member in an axial direction. Elastic restoring force applied by the second sealing member to the valve seat member is larger than elastic restoring force applied by the first sealing member to the valve seat member.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2011-186333 filed on Aug. 29, 2011, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a fluid control electromagnetic valve which controls a flow of fluid.

BACKGROUND

Conventionally, a fluid control electromagnetic valve is known. In the valve, a fixed core and a movable valving element are accommodated in a resin body that defines a flow passage through which fluid flows. In this kind of fluid control electromagnetic valve, the movable valving element is reciprocated in the axial direction between an initial position and attraction position as described in, for example, JP-A-2006-153231 corresponding to US2006/0117553A1.

Specifically, the movable valving element is attracted from the initial position into the attraction position as a result of generation of electromagnetic attraction force applied to a movable core of the valving element by the fixed core. Accordingly, the movable valving element is disengaged from a fixed valve seat which is formed from the resin body so as to open a fluid passage. On the other hand, the movable valving element returns to the initial position from the attraction position due to disappearance of the electromagnetic attraction force to be engaged with the fixed valve seat. Consequently, the movable valving element closes the fluid passage. As a result of the opening and closing operations of the fluid passage using such electromagnetic actuation of the movable valving element, a flow of fluid through the fluid passage can be accurately controlled. Particularly, in the structure of JP-A-2006-153231 in which the fluid passage is connected between a fuel tank which stores fuel, and a canister that adsorbs fuel vapor formed as a result of evaporation of fuel inside the tank, control accuracy of a flow of mixture of the fuel vapor and air from the fuel tank toward the canister can be ensured.

It is described in JP-A-2006-153231 that the resin body which accommodates the fixed core and the movable valving element, and the resin body which is formed into the fixed valve seat are formed from the same polybutylene terephthalate and are fixed by caulking to each other. In this case, the polybutylene terephthalate is a resin having a larger linear expansion coefficient than a metal from which the fixed core and the movable core are formed. Therefore, particularly in an environment around an engine as in JP-A-2006-153231, each resin body is subject to heat and easily expanded.

The attraction position among movement positions of the movable valving element is determined depending on a position of the metal fixed core, which attracts the metal movable core, whereas the initial position of the movable valving element is determined according to a position of the fixed valve seat with which the movable valving element is engaged. Accordingly, when the fixed valve seat is disengaged from the fixed core by the thermal expansion of each resin body as described above, the initial position is also separated from the attraction position. As a result, a flow rate of fluid flowing through a clearance between the movable valving element at the attraction position and the fixed valve seat varies in the fluid passage. Thus, accuracy in control of a flow of fluid through the fluid passage may be deteriorated.

SUMMARY

According to the present disclosure, there is provided a fluid control electromagnetic valve for controlling a flow of fluid, including a fixed core, a movable valving element, a resin body, a valve seat member, a first sealing member, and a second sealing member. The fixed core is formed from metal and is configured to generate electromagnetic attraction force. The movable valving element includes a movable core formed from metal. The movable valving element is attracted from an initial position to an attraction position as a result of application of the electromagnetic attraction force to the movable core and is returned from the attraction position to the initial position as a result of disappearance of the electromagnetic attraction force, so that the movable valving element reciprocates in its axial direction between the initial position and the attraction position. The resin body accommodates therein the fixed core and the movable valving element and includes therein a fluid passage through which fluid flows. The valve seat member is formed from a material having a smaller linear expansion coefficient than the resin body and is accommodated in the resin body. The valve seat member includes a fixed valve seat, and the movable valving element is engaged with or disengaged from the fixed valve seat. The fluid passage is opened as a result of the disengagement of the movable valving element at the attraction position from the fixed valve seat and the fluid passage is closed as a result of the engagement of the movable valving element at the initial position with the fixed valve seat. The first sealing member is accommodated in the resin body in an elastic compression state to seal the fluid passage and is positioned around the fixed core. The second sealing member is accommodated in the resin body in an elastic compression state to seal the fluid passage. The valve seat member is clamped between the second sealing member and the first sealing member in the axial direction. Elastic restoring force applied by the second sealing member to the valve seat member is larger than elastic restoring force applied by the first sealing member to the valve seat member.

DETAILED DESCRIPTION

Embodiments will be described below with reference to the accompanying drawings. By using the same numerals to indicate corresponding components in the embodiments, repeated explanations may be omitted. In each embodiment, when only a part of a configuration is described, configuration(s) in the previously described other embodiment(s) can be applied to the other parts of the configuration. In addition to a combination of configurations indicated in the description in each embodiment, although not indicated, configurations in more than one embodiment are partly combinable unless the combination particularly interferes with each other.

FIG. 1illustrates an application of a fluid control electromagnetic valve1according to a first embodiment to a system which processes fuel vapor. A fluid passage2formed in the fluid control electromagnetic valve1communicates with a tank passage5and a canister passage6extending respectively from a fuel tank3and a canister4in a vehicle. The fuel tank3stores volatile fuel such as gasoline fuel supplied to an internal combustion engine7of the vehicle. In the fuel tank3, fuel vapor is generated as a result of evaporation of the stored fuel, and the fuel vapor is mixed with air. A fuel-air mixture obtained by mixing the fuel vapor and air flows from the fuel tank3into the tank passage5to reach the inside of the canister4through the fluid passage2and the canister passage6at the time of opening of the fluid control electromagnetic valve1. The canister4accommodates an adsorbent4ato be capable of adsorbing the fuel vapor in the fuel-air mixture which has reached the inside of the canister4. In addition, the canister4communicates with a purge passage8that opens into an intake passage7aof the engine7in the vehicle. Accordingly, at the time of opening of a purge valve8aalong the purge passage8, a negative pressure generated in the intake passage7ais applied to the inside of the canister4, so that the fuel vapor is separated from the adsorbent4ato be purged away into the intake passage7a.

A specific configuration of the fluid control electromagnetic valve1will be described below. The fluid control electromagnetic valve1, which controls a flow of the fuel-air mixture from the fuel tank3toward the canister4, includes, as illustrated inFIGS. 2 to 4, a resin body10, a valve seat member20, a fixed core30, a movable valving element40, a valve spring50, a solenoid coil60, and a terminal70.

The resin body10is obtained by combining together a resin housing11and a resin cover12, and has a hollow shape as a whole. The resin housing11and the resin cover12are formed from, for example, resin of polyamide 66 (PA66) or polybutylene terephthalate (PBT) having a relatively high linear expansion coefficient. Particularly, in the present embodiment, the resin housing11is formed from a resin that is colored so as to have absorptivity for a laser, and the resin cover12is formed from a resin of the same kind as the resin housing11with permeability for a laser.

The resin body10is formed by insert-molding whereby the components30,60,70and so forth are embedded into its forming resin, and includes first to third accommodating portions110to112, a joining portion113, a connector portion114, an input port portion115, and an attachment portion116.

The cylindrical first accommodating portion110illustrated inFIG. 2accommodates the fixed core30and the solenoid coil60in their fixed state, and accommodates a part of the movable valving element40and the valve spring50in their movable state. The annular plate-like second accommodating portion111is located coaxially adjacent to the first accommodating portion110, and includes a fluid chamber111a, which accommodates a part of the movable valving element40in its movable state, in the portion111. In the present embodiment, thickness of the second accommodating portion111in the axial direction is set at such a thickness that thermal expansion of the portion111in the axial direction is substantially negligibly-small despite a relatively high linear expansion coefficient of the portion111. The cylindrical third accommodating portion112is located coaxially adjacent to the second accommodating portion111on the opposite side of the portion111from the first accommodating portion110in the axial direction. The portion112respectively accommodates the valve seat member20in its fixed state and a part of the movable valving element40in its movable state. The joining portion113having a generally trapezoidal cylindrical shape (see alsoFIG. 3) is located eccentrically adjacent to the third accommodating portion112on the opposite side of the portion112from the second accommodating portion111in the axial direction.

The connector portion114is formed in a cylindrical shape having a bottom that projects radially outward from the first accommodating portion110, and accommodates the terminal70in its fixed state. As illustrated inFIGS. 2 to 4, the input port portion115is formed in a cylindrical shape that projects radially outward from the third accommodating portion112, and includes an input passage2aof the fluid passage2, which communicates with the tank passage5, in the portion115. The attachment portion116is attached to, for example, an upper wall portion of the fuel tank3via a bolt (not shown).

The resin cover12, which constitutes the resin body10together with the resin housing11having such a configuration, includes an insertion portion120and an output port portion121. The insertion portion120having a generally trapezoidal cylindrical shape is coaxially fitted into an inner peripheral surface of the joining portion113, and includes a communication passage2bof the fluid passage2in the portion120. In the present embodiment, the insertion portion120and the joining portion113respectively have annular plate-like joining flanges120a,113a, and the whole regions of these flanges120a,113ain their circumferential direction are joined together by laser-welding. As illustrated inFIGS. 2 and 3, the output port portion121is formed in a cylindrical shape that projects from the insertion portion120on the opposite side from the joining portion113in the axial direction, and includes the communication passage2bof the fluid passage2and an output passage2cof the fluid passage2that communicates with the canister passage6, in the portion121.

As illustrated inFIGS. 2 and 4, the valve seat member20is formed in a hollow shape as a whole from resin such as polyphenylene sulfide (PPS) having a smaller linear expansion coefficient than the components11,12of the resin body10. The valve seat member20has a fourth accommodating portion200and a partition portion201.

As illustrated inFIG. 2, the cylindrical fourth accommodating portion200is disposed at a position between the second accommodating portion111and the insertion portion120in the axial direction, and is coaxially fitted and fixed on an inner peripheral surface of the third accommodating portion112. The fourth accommodating portion200includes a valve passage2dof the fluid passage2that accommodates a part of the movable valving element40in its movable state in the portion200. The valve passage2dcommunicates between the input passage2aand the communication passage2b. The fourth accommodating portion200includes a fixed valve seat200a, and the fixed valve seat200a, which is exposed to a halfway portion of the valve passage2d, is formed in an annular belt surface shape coaxial with the accommodating portions110to112and the output port portion121. As illustrated inFIGS. 2 and 4, the partition portion201is formed in a flat plate shape that projects radially outward from the fourth accommodating portion200. The partition portion201divides the input passage2afrom the communication passage2band divides the valve passage2d(specifically, a passage portion2dudescribed hereinafter) from the communication passage2b.

As illustrated inFIG. 2, the fixed core30is obtained as a result of combination of a plate core32and a yoke core33with a core main body31. The core main body31, the plate core32, and the yoke core33are formed from magnetic metals which have smaller linear expansion coefficients than the components11,12of the resin body10and which are the same as or different from each other.

The cylindrical core main body31is disposed inside the first accommodating portion110coaxially with the portion110. The core main body31includes an attracting part310for electromagnetically attracting the movable valving element40at its intermediate part in the axial direction. The annular plate-like plate core32is coaxially fitted on an outer peripheral surface of one end part of the core main body31in its axial direction, so that the plate core32is connected magnetically to the core main body31. The L-shaped plate-like yoke core33is coaxially fitted on an outer peripheral surface of the other end portion of the core main body31in its axial direction, and passes and is fitted through the plate core32in the axial direction. The yoke core33is thereby connected magnetically to these core main body31and the plate core32.

The movable valving element40is obtained by combination of a valve member43and a buffer member44with a movable core41and a shaft member42. As inFIGS. 2 and 5, the movable valving element40is disposed such that the entire element40straddles the first to third accommodating portions110to112at any movement position.FIG. 2illustrates the initial position of the movable valving element40, andFIG. 5illustrates an attraction position of the movable valving element40.

The cylindrical movable core41is formed from magnetic metal, and disposed inside the core main body31coaxially with the main body31, and can slidably reciprocate in the axial direction on an inner peripheral surface of the core main body31. As a result of the generation of electromagnetic attraction force between the movable core41and the attracting part310, which is opposed to the movable core41in the axial direction, the movable core41is displaced from the initial position inFIG. 2to the attraction position inFIG. 5along with the other components42to44of the movable valving element40. On the other hand, as a result of disappearance of the electromagnetic attraction force between the movable core41and the attracting part310, the movable core41is displaced from the attraction position inFIG. 5to the initial position inFIG. 2along with the other components42to44of the movable valving element40.

The cylindrical shaft member42is formed from metal having a smaller linear expansion coefficient than the components11,12of the resin body10, and coaxially fitted and fixed on an inner peripheral surface of the movable core41, so that the shaft member42projects further on the opposite side from the attracting part310in the axial direction than the movable core41. The cylindrical valve member43is formed from, for example, polyphenylene sulfide (PPS) which is a resin having a smaller linear expansion coefficient than the components11,12of the resin body10, to have a shorter axial length than the shaft member42. The valve member43is coaxially fitted and fixed on an outer peripheral surface of a portion of the shaft member42exposed from the movable core41. An annular plate-like holding flange430, which is opposed to the fixed valve seat200ain the axial direction, is formed integrally with an end portion of the valve member43on its opposite side from the movable core41in the axial direction.

The buffer member44is formed from rubber into a cylindrical shape extending with a C-shaped (horseshoe-shaped) cross-section. The buffer member44is coaxially held by the valve member43in a mode to clamp the holding flange430from its both sides in the axial direction. At the initial position inFIG. 2, the buffer member44is engaged with the fixed valve seat200ato be in a valve-closing state to close the valve passage2dof the fluid passage2. On the other hand, at the attraction position inFIG. 5, the buffer member44is disengaged from the fixed valve seat200ato be in a valve-opening state to open the valve passage2dof the fluid passage2.

A longitudinal hole400and a lateral hole401are provided for the movable valving element40of the present embodiment. The longitudinal hole400is formed as an inner hole of the shaft member42, and communicates with the valve passage2don its opposite side from the movable core41in the axial direction. The lateral hole401passes through the shaft member42and the valve member43by radially straddling the member42,43so as to communicate with the longitudinal hole400and the fluid chamber111a.

The valve spring50is a compression coil spring made of metal, and is disposed inside the core main body31coaxially with the main body31. One end part of the valve spring50in its axial direction is engaged with a spring guide51, which is fitted and fixed on an inner peripheral surface of the core main body31. The other end part of the valve spring50in its axial direction is in contact with an end face of the movable core41in its axial direction on the attracting part310-side. As a result of such a mode of its engagement and contact, the valve spring50urges the movable valving element40from the attraction position inFIG. 5toward the initial position inFIG. 2.

The solenoid coil60having a cylindrical shape as a whole is obtained by winding a metal wire material around a resin bobbin61, and is disposed inside the first accommodating portion110at a position between the core main body31and the yoke core33in the radial direction. The solenoid coil60is connected electrically to the metal terminal70which is embedded in the connector portion114, and is energization-controlled by an external control unit9(seeFIG. 1) through the terminal70. The solenoid coil60is excited upon its energization by the control unit9to pass a magnetic flux through the fixed core30and the movable core41. As a result, electromagnetic attraction force for magnetically attracting the movable core41to the attracting part310is generated, so that the movable valving element40is displaced to the attraction position inFIG. 5. On the other hand, the solenoid coil60is demagnetized as a result of a stop of its energization by the control unit9to eliminate the magnetic flux passing through the fixed core30and the movable core41. As a result, electromagnetic attraction force applied between the attracting part310and the movable core41also disappears. Accordingly, the movable valving element40, which is urged by the valve spring50, is displaced to the initial position inFIG. 2.

As illustrated inFIGS. 2 and 4, the fluid control electromagnetic valve1further includes a first sealing member80and a second sealing member90.

As illustrated inFIG. 2, the first sealing member80is formed from rubber into a thin-film annular shape, and is accommodated in the third accommodating portion112coaxially with the portion112. An outer circumferential sealing portion800of the first sealing member80is clamped between the second accommodating portion111and the fourth accommodating portion200in the axial direction, so that the sealing portion800is positioned at a neighboring part of the plate core32, which is adjacent to the thin-walled second accommodating portion111in the axial direction. In such a positioning state, the outer circumferential sealing portion800applies elastic restoring force on their axially repulsive side to the portions111,200due to its elastic compression between the second accommodating portion111and the fourth accommodating portion200. At the same time, the sealing portion800seals the valve passage2dof the fluid passage2and the fluid chamber111awith respect to the outside.

A portion of the first sealing member80radially inward of the outer circumferential sealing portion800has flexibility to function as a diaphragm portion801that divides the fluid chamber111afrom the valve passage2d.The diaphragm portion801surrounds the movable valving element40coaxially with the element40, and is fixed on an outer peripheral surface of the valve member43. As a result of the above-described configuration, at the initial position inFIG. 2, a passage portion2dlof the valve passage2don the communication passage2b-side of the fixed valve seat200acommunicates with the fluid chamber111athrough the lateral hole401and the longitudinal hole400. Consequently, a pressure in the fluid chamber111ais substantially the same as a pressure in the passage portion2dl. Thus, if a passage portion2duof the valve passage2don the input passage2a-side of the fixed valve seat200ahas a lower pressure than the passage portion2dl, a movement of the movable valving element40at the initial position despite the disappearance of electromagnetic attraction force between the cores30,41can be limited.

As illustrated inFIGS. 2 and 4, the second sealing member90is formed from rubber into a generally trapezoidal annular shape extending with an elliptical cross-section. The second sealing member90is accommodated in the third accommodating portion112with a portion of the member90in its circumferential direction opposed to the outer circumferential sealing portion800of the first sealing member80in the axial direction. In the axial direction, the second sealing member90is clamped between the fourth accommodating portion200and the insertion portion120, and the fourth accommodating portion200is clamped between the member90and the outer circumferential sealing portion800of the first sealing member80. As a result of such a clamping mode, due to its elastic compression between the fourth accommodating portion200and the insertion portion120, the second sealing member90applies elastic restoring force on their axially repulsive side to the portions200,120. At the same time, the member90seals the communication passage2bof the fluid passage2from the outside. In addition, at the initial position inFIG. 2, the second sealing member90fulfills a function of sealing a clearance between the passage portions2dl,2duof the valve passage2din collaboration with the first sealing member80.

The second sealing member90of the present embodiment is formed from a rubber same as the first sealing member80to be thicker in the axial direction than the first sealing member80. As a result of such a forming mode, the elastic restoring force, which is applied to one end part of the fourth accommodating portion200in its axial direction by the second sealing member90, is set to be larger than the elastic restoring force, which is applied to the other end portion of the fourth accommodating portion200in its axial direction by the first sealing member80.

Next, the overall operation of the fluid control electromagnetic valve1will be described. Upon an oil supply whereby fuel is supplied to the fuel tank3from the outside of the vehicle, the control unit9starts energization of the solenoid coil60. Accordingly, as a result of the generation of electromagnetic attraction force between the cores30,41by the excitation of the solenoid coil60, the movable valving element40is displaced from the initial position inFIG. 2toward the attraction position inFIG. 5. Consequently, the movable valving element40is disengaged from the fixed valve seat200ato be in a valve-opening state, so that the valve passage2dis opened and the passage portions2du,2dlof the passage2dcommunicate with each other. Meanwhile, inside the fuel tank3, the pressure increases in accordance with the oil supply, and the amount of fuel vapor generated is increased. Therefore, in a valve-opening state, a mixture of the fuel vapor and air inside the fuel tank3flows into the input passage2aand the passage portion2duon an upstream side of the fixed valve seat200a, and is further guided into the canister4via the passage portion2dland the passages2b,2con a downstream side of the fixed valve seat200a.

On the other hand, the control unit9stops the energization of the solenoid coil60upon completion of the oil supply to the fuel tank3. Accordingly, as a result of the disappearance of electromagnetic attraction force between the cores30,41by the demagnetization of the solenoid coil60, the movable valving element40is displaced from the attraction position inFIG. 5to the initial position inFIG. 2. Consequently, the movable valving element40is engaged with the fixed valve seat200ato be in a valve-closing state, so that the passage portions2du,2dlare disconnected to each other and the valve passage2dis closed. Thus, in a valve-closing state, a flow of the fuel-air mixture from the inside of the fuel tank3into the canister4is inhibited.

Operation and its effects of the above-described fluid control electromagnetic valve1will be explained below. Among the displacement positions of the movable valving element40in the fluid control electromagnetic valve1, the attraction position inFIG. 5is determined in accordance with a position of the metal fixed core30which attracts the metal movable core41, whereas the initial position inFIG. 2is determined depending on a position of the fixed valve seat200awith which the movable valving element40is engaged. Accordingly, in order to secure accuracy in control of a flow of fluid through the passage2by means of the opening and closing operations of the fluid passage2using the electromagnetic actuation of the movable valving element40, it is important to stabilize a relative position of the fixed valve seat200awith respect to the fixed core30to maintain a separation distance (clearance) between the attraction position and initial position.

Based on such knowledge, the valve seat member20of the fluid control electromagnetic valve1is set to have a smaller linear expansion coefficient than the resin housing11and the resin cover12which constitute the resin body10. As a result, thermal expansion of the member20can be limited. The fourth accommodating portion200of the valve seat member20is clamped between the first sealing member80, which is positioned at the neighboring part of the plate core32of the fixed core30to seal the fluid passage2, and the second sealing member90, which is provided to seal this fluid passage2. Consequently, the valve seat member20can be properly positioned relative to the metal fixed core30including the plate core32via the first sealing member80.

In the case of the valve seat member20, the elastic restoring force that is applied to this fourth accommodating portion200by the second sealing member90in an elastic compression state is larger than the elastic restoring force that is applied to the fourth accommodating portion200by the first sealing member80in an elastic compression state. Accordingly, the fourth accommodating portion200is pressed on the first sealing member80in accordance with a difference between the elastic restoring forces applied by the sealing members80,90. Therefore, the function of positioning the valve seat member20relative to the fixed core30does not easily vary.

For these reasons, as for the valve seat member20thermal expansion of which is restrained and which is positioned relative to the fixed core30, a relative position of the fixed valve seat200aof the member20with respect to the fixed core30can be stabilized. Accordingly, even if the resin body10having a high linear expansion coefficient is thermally-expanded, a fluctuation of a flow rate of the fuel-air mixture which is made to flow through a clearance between the element40and the fixed valve seat200ain the valve passage2dby the movable valving element40at the attraction position with the separation distance between the attraction position and the initial position maintained can be limited. Thus, it is possible to ensure accuracy in control of the flow of the fuel-air mixture in the fluid passage2including the valve passage2d.

In addition, when the resin body10is formed in a process of production of the fluid control electromagnetic valve1, the resin cover12is inserted into the resin housing11in which the components20,30,40,50,60,70,80,90are accommodated, and the housing11and the cover12are joined together by laser-welding. Consequently, at the same time as the formation of the resin body10, the second sealing member90, which is formed from the same material as the first sealing member80and which is more thick-walled in its axial direction than the first sealing member80, is clamped between the valve seat member20and the resin cover12, and the member90can thereby be elastically compressed reliably. As a result, an improvement in productivity of the valve1is made, and the generation of the elastic restoring force which is larger than the first sealing member80is consolidated by the second sealing member90. Therefore, reliability in the effect of securing the accuracy in flow control can be improved.

As illustrated inFIG. 6, a second embodiment is a modification to the first embodiment. In a fluid control electromagnetic valve2001of the second embodiment, a resin housing2011of a resin body2010does not include a second accommodating portion111. Accordingly, an outer circumferential sealing portion2800of a first sealing member80is clamped between a plate core32and a fourth accommodating portion200in the axial direction, so that the portion2800is stably positioned around the plate core32. Hence, a valve seat member20can be stably positioned via the first sealing member80relative to a metal fixed core30including the plate core32.

Moreover, in the fluid control electromagnetic valve2001, elastic restoring force applied to the fourth accommodating portion200by a second sealing member90is larger than elastic restoring force applied to this fourth accommodating portion200by the first sealing member80due to its elastic compression between the plate core32and the fourth accommodating portion200. Consequently, operation of positioning the valve seat member20relative to the fixed core30does not easily vary on the same principle as the first embodiment.

A linear expansion coefficient of the valve seat member20of the second embodiment is also set to be smaller than the resin housing2011and a resin cover12which constitute the resin body2010, and thermal expansion of the member20can thereby be limited. As a result, as described above, a relative position of a fixed valve seat200aof the valve seat member20with respect to the fixed core30can be made stable. Therefore, a flow rate change, which deteriorates the accuracy in control of the flow of the fuel-air mixture, can be curbed through a clearance between the valve seat200aand a movable valving element40in a valve passage2d.

As illustrated inFIGS. 7 and 8, a third embodiment is a modification to the first embodiment. In a fluid control electromagnetic valve3001of the third embodiment, a negative pressure relief passage3002eand a positive pressure relief passage3002fare provided for a partition portion3201of a valve seat member3020as a part of a fluid passage3002. The relief passages3002e,3002fpass through the partition portion3201at positions of the partition portion3201which are away from each other, in the shapes of cylindrical holes. Accordingly, the passages3002e,3002fcan communicate with an input passage2aand a communication passage2bof the fluid passage3002.

In the fluid control electromagnetic valve3001, a negative pressure relief valving element3046and a negative pressure relief spring3047are accommodated in a movable state in the input passage2ainside an input port portion3115of a resin housing3011which constitutes a resin body3010. The negative pressure relief valving element3046is obtained as a result of holding an annular rubber buffer member3461by a resin valve member3460having a shape of a circular disk, and is disposed coaxially with the negative pressure relief passage3002e. By such an arrangement mode, in the case of the negative pressure relief valving element3046, the buffer member3461can be engaged with or disengaged from a negative pressure valve seat3201a, which is formed on the partition portion3201around the negative pressure relief passage3002e.

The negative pressure relief spring3047, which is a metal compression coil spring, is disposed inside a partially-cylindrical negative pressure valve guide3115aformed integrally with the input port portion3115coaxially with the guide3115a. One end part of the negative pressure relief spring3047in its axial direction is engaged with the input port portion3115, and the other end part of the negative pressure relief spring3047in its axial direction is in contact with the valve member3460. As a result of such a mode of its engagement and contact, the negative pressure relief spring3047urges the negative pressure relief valving element3046toward the negative pressure valve seat3201a.

Because of such a collaboration between the negative pressure relief valving element3046and the negative pressure relief spring3047, in the fluid control electromagnetic valve3001, the negative pressure relief valving element3046is opened in accordance with internal pressure of a fuel tank3in a valve-closing state of a movable valving element40. Specifically, when the internal pressure of the fuel tank3falls below a negative pressure side limit pressure, which is lower than the atmospheric pressure by a predetermined amount, due to, for example, temperature decrease, the negative pressure relief valving element3046is disengaged from the negative pressure valve seat3201aagainst the urging operation of the negative pressure relief spring3047, which leads to a valve-opening state in which the passages2b,2acommunicate with each other. In such a valve-opening state, air in a canister4is drawn into the fuel tank3through the passages2b,2a, so that the internal pressure of the fuel tank3increases. Thus, deformation of the fuel tank3due to the application of negative pressure to the tank3can be avoided. When the internal pressure of the fuel tank3rises above the negative pressure side limit pressure, the negative pressure relief valving element3046is engaged with the negative pressure valve seat3201aby the urging operation of the negative pressure relief spring3047. Accordingly, the communication between the passages2b,2ais blocked.

In the fluid control electromagnetic valve3001, a positive pressure relief valving element3048and a positive pressure relief spring3049are accommodated in a movable state in the communication passage2binside an insertion portion3120of a resin cover3012which constitutes the resin body3010. The positive pressure relief valving element3048is obtained as a result of holding an annular rubber buffer member3481by a resin valve member3480having a shape of a circular disk, and is disposed coaxially with the positive pressure relief passage3002f. By such an arrangement mode, in the case of the positive pressure relief valving element3048, the buffer member3481can be engaged with or disengaged from a positive pressure valve seat3201b, which is formed on the partition portion3201around the positive pressure relief passage3002f.

The positive pressure relief spring3049, which is a metal compression coil spring, is disposed inside a partially-cylindrical positive pressure valve guide3201cformed integrally with the partition portion3201coaxially with the guide3201c. One end part of the positive pressure relief spring3049in its axial direction is engaged with the insertion portion3120, and the other end part of the positive pressure relief spring3049in its axial direction is in contact with the valve member3480. As a result of such a mode of its engagement and contact, the positive pressure relief spring3049urges the positive pressure relief valving element3048toward the positive pressure valve seat3201b.

Because of such a collaboration between the positive pressure relief valving element3048and the positive pressure relief spring3049, in the fluid control electromagnetic valve3001, the positive pressure relief valving element3048is opened in accordance with internal pressure of the fuel tank3in a valve-closing state of the movable valving element40. Specifically, when the internal pressure of the fuel tank3rises above a positive pressure side limit pressure, which is higher than the atmospheric pressure by a predetermined amount, due to, for example, temperature increase, the positive pressure relief valving element3048is disengaged from the positive pressure valve seat3201bagainst the urging operation of the positive pressure relief spring3049, which leads to a valve-opening state in which the passages2a,2bcommunicate with each other. In such a valve-opening state, the fuel-air mixture in the fuel tank3is pushed out into the canister4through the passages2a,2b, so that the pressure in the fuel tank3is decreased. Thus, deformation of the fuel tank3due to the application of high positive pressure to the tank3can be avoided. When the internal pressure of the fuel tank3falls below the positive pressure side limit pressure, the positive pressure relief valving element3048is engaged with the positive pressure valve seat3201bby the urging operation of the positive pressure relief spring3049. Accordingly, the communication between the passages2a,2bis blocked.

Except for the above-described points, in the fluid control electromagnetic valve3001, substantially the same configuration as the first embodiment is employed. Thus, securing of the accuracy in control of the flow of the fuel-air mixture through the fluid passage3002, and improvement of reliability in this securing effect become possible along with the avoidance of deformation of the fuel tank3.

As illustrated inFIGS. 9 and 10, a fourth embodiment is a modification to the first embodiment. In a fluid control electromagnetic valve4001of the fourth embodiment, a partition portion4201of a valve seat member4020includes a partition main body4201aand a projecting valve seat4201b. The partition main body4201ais formed in a cylindrical shape that projects from a fourth accommodating portion200on the opposite side from a second accommodating portion111in the axial direction coaxially with them. The partition main body4201ais disposed in a passage portion2dlof a valve passage2don a communication passage2b-side of a fixed valve seat200a, and divides this passage portion2dlfrom an input passage2aand the communication passage2b. The projecting valve seats4201bproject radially inward from more than one position of the partition main body4201aat regular intervals in the circumferential direction.

As illustrated inFIG. 9, in the fluid control electromagnetic valve4001, an insertion portion4120of a resin cover4012which constitutes a resin body4010is formed in a cylindrical shape that is coaxial with the partition main body4201atogether with a joining portion4113of a resin housing4011which constitutes the resin body4010. A second sealing member4090, which is clamped between these insertion portion4120and partition main body4201a, is formed from rubber into an annular shape (see alsoFIG. 10) extending with an elliptical cross-section, and the entire sealing member4090in the circumferential direction is opposed to its coaxial first sealing member80. As a result of such an opposing mode, the annular second sealing member4090produces elastic restoring force which is larger than its coaxial annular first sealing member80in the entire circumferential direction so as to reduce variation in pressing pressure of the fourth accommodating portion200against the first sealing member80in the circumferential direction.

In the fluid control electromagnetic valve4001, a flow regulating valving element4048and a flow regulating spring4049are accommodated in a movable state in the communication passage2binside the insertion portion4120. The flow regulating valving element4048is formed from resin in a shape of an annular plate, and is disposed coaxially with the partition main body4201a. As a result of such an arrangement mode, with regard to the flow regulating valving element4048, an outer circumferential portion4480having a smaller diameter than the partition main body4201acan be engaged with or disengaged from the respective projecting valve seats4201b. As well, regarding the flow regulating valving element4048, the outer circumferential portion4480can be engaged with or disengaged from a flow regulating valve seat4120ain a shape of an annular belt surface formed at an inner peripheral part of the insertion portion4120.

As illustrated inFIGS. 9 and 10, the flow regulating valving element4048includes a penetration passage4002epassing through the element4048in the axial direction as a part of a fluid passage4002. In a state of engagement of the flow regulating valving element4048with the projecting valve seats4201b, clearance passages4002fas a part of the fluid passage4002are formed between the flow regulating valving element4048and the partition main body4201a. A sum of passage areas of the respective clearance passages4002fis set to be sufficiently larger than a passage area of the penetration passage4002e.

As illustrated inFIG. 9, the flow regulating spring4049, which is a metal compression coil spring, is disposed in the communication passage2binside the insertion portion4120coaxially with the passage2b. One end part of the flow regulating spring4049in its axial direction is engaged with an annular plate-like locking piece4120bwhich is formed integrally with the insertion portion4120, and the other end part of the flow regulating spring4049in its axial direction is in contact with the flow regulating valving element4048. As a result of such a mode of its engagement and contact, the flow regulating spring4049urges the flow regulating valving element4048toward the respective projecting valve seats4201b.

Because of such a collaboration between the flow regulating valving element4048and the flow regulating spring4049, in the fluid control electromagnetic valve4001, the flow regulating valving element4048is opened in accordance with internal pressure of a fuel tank3in a valve-opening state of a movable valving element40. Specifically, during the oil supply in which the movable valving element40is opened, when the internal pressure of the fuel tank3becomes higher than a set pressure, the flow regulating valving element4048which is disengaged from the respective projecting valve seats4201bagainst the urging operation of the flow regulating spring4049is engaged with the flow regulating valve seat4120a. As a result, the passage portion2dlof the valve passage2dcommunicates with the communication passage2bthrough the penetration passage4002ehaving a small passage area. Consequently, a flow rate of the fuel-air mixture that is pushed out from the inside of the fuel tank3through the passages2a,2d,4002e,2b,2cinto a canister4is reduced. Hence, a leakage of fuel vapor that is no longer adsorbed due to the amount of fuel vapor in the fuel-air mixture which reaches the inside of the canister4being beyond adsorption capability of an adsorbent4acan be avoided.

On the other hand, during the oil supply in which the movable valving element40is opened, when the internal pressure of the fuel tank3becomes lower than the set pressure, the flow regulating valving element4048, which is disengaged from the flow regulating valve seat4120aby the urging operation of the flow regulating spring4049, is engaged with the respective projecting valve seats4201b. As a result, the passage portion2dlof the valve passage2dcommunicates with the communication passage2bvia the respective clearance passages4002fwith their large total passage area. Accordingly, the flow rate of the fuel-air mixture that is pushed out from the inside of the fuel tank3through the passages2a,2d,4002f,2b,2cinto the canister4increases. Thus, even if the internal pressure of the fuel tank3is low, the fuel-air mixture is reliably released, and the leakage of fuel vapor from the tank3can thereby be avoided.

Except for the above-described points, in the fluid control electromagnetic valve4001, substantially the same configuration as the first embodiment is employed. Accordingly, securing of the accuracy in control of the flow of the fuel-air mixture through the fluid passage4002, and further improvement of reliability in this securing effect as a result of the reduction of variation in the pressing pressure of the fourth accommodating portion200against the first sealing member80become possible along with avoidance of the leakage of fuel vapor.

Modifications to the above embodiments will be described. The embodiments have been described above. Nevertheless, the disclosure is not interpreted by limiting itself to these embodiments, and may be applied to various embodiments and combinations without departing from the scope of the disclosure.

Specifically, in the first to fourth embodiments, the linear expansion coefficients of the resin housings11,2011,3011,4011and the resin covers12,3012,4012, which respectively constitute the resin bodies10,2010,3010,4010, may be different from each other as long as they are larger than the valve seat members20,3020,4020. In this case, for example, by forming the resin housings11,2011,3011,4011and the resin covers12,3012,4012from different materials which have laser absorptivity and whose melting points are close to each other, they can be joined together through laser-welding similar to the cases of the first to fourth embodiments. Moreover, the valve seat members20,3020,4020of the first to fourth embodiments may be formed from materials other than resin, for example, metal, as long as their linear expansion coefficients are smaller than the resin housings11,2011,3011,4011and the resin covers12,3012,4012.

The sealing members80,90,4090of the first to fourth embodiments may be formed from rubbers which are different from each other, or may be formed to have axial thicknesses which are the same as each other. Furthermore, as illustrated in a modification (FIG. 11is a modification to the first embodiment) ofFIG. 11, the first sealing member80of the first to fourth embodiments may consist only of a ring body5802that is clamped between the second accommodating portion111or the plate core32and the fourth accommodating portion200, so that the first sealing member80has a configuration that does not fulfill the function as the diaphragm portion801.

The first sealing member80of the third and fourth embodiments may be clamped between the plate core32of the fixed core30and the fourth accommodating portion200of the valve seat members20,3020,4020according as the second embodiment. Also, the entire second sealing member90of the first to third embodiments in its circumferential direction may be opposed to its coaxial first sealing member80according as the fourth embodiment. In addition, a part of the second sealing member4090of the fourth embodiment in its circumferential direction may be axially opposed to the first sealing member80according as the first to third embodiments.

The present disclosure can be applied to fluid control electromagnetic valves that control flows of various fluids, other than the fluid control electromagnetic valves1,2001,3001,4001that control a flow of the mixture of fuel vapor and air in the system which processes fuel vapor.

To sum up, the fluid control electromagnetic valve1,2001,3001,4001of the above embodiments can be described as follows.

A fluid control electromagnetic valve1,2001,3001,4001for controlling a flow of fluid, includes a fixed core30, a movable valving element40, a resin body10,2010,3010,4010, a valve seat member20,3020,4020, a first sealing member80,5802, and a second sealing member90,4090. The fixed core30is formed from metal and is configured to generate electromagnetic attraction force. The movable valving element40includes a movable core41formed from metal. The movable valving element40is attracted from an initial position to an attraction position as a result of application of the electromagnetic attraction force to the movable core41and is returned from the attraction position to the initial position as a result of disappearance of the electromagnetic attraction force, so that the movable valving element40reciprocates in its axial direction between the initial position and the attraction position. The resin body10,2010,3010,4010accommodates therein the fixed core30and the movable valving element40and includes therein a fluid passage2,3002,4002through which fluid flows. The valve seat member20,3020,4020is formed from a material having a smaller linear expansion coefficient than the resin body10,2010,3010,4010and is accommodated in the resin body10,2010,3010,4010. The valve seat member20,3020,4020includes a fixed valve seat200a, and the movable valving element40is engaged with or disengaged from the fixed valve seat200a. The fluid passage2,3002,4002is opened as a result of the disengagement of the movable valving element40at the attraction position from the fixed valve seat200aand the fluid passage2,3002,4002is closed as a result of the engagement of the movable valving element40at the initial position with the fixed valve seat200a. The first sealing member80,5802is accommodated in the resin body10,2010,3010,4010in an elastic compression state to seal the fluid passage2,3002,4002and is positioned around the fixed core30. The second sealing member90,4090is accommodated in the resin body10,2010,3010,4010in an elastic compression state to seal the fluid passage2,3002,4002. The valve seat member20,3020,4020is clamped between the second sealing member90,4090and the first sealing member80,5802in the axial direction. Elastic restoring force applied by the second sealing member90,4090to the valve seat member20,3020,4020is larger than elastic restoring force applied by the first sealing member80,5802to the valve seat member20,3020,4020.

The movable valving element40, which reciprocates in the axial direction between the initial position and the attraction position inside the resin body10,2010,3010,4010, is attracted from the initial position to the attraction position due to the generation of electromagnetic attraction force applied by the fixed core30to the movable core41of the element40. Accordingly, the element40is disengaged from the fixed valve seat200aof the valve seat member20,3020,4020so as to open the fluid passage2,3002,4002. On the other hand, the movable valving element40returns from the attraction position to the initial position due to the disappearance of electromagnetic attraction force to be engaged with the fixed valve seat200a. Consequently, the element40closes the fluid passage2,3002,4002. The attraction position among movement positions of the movable valving element40is determined depending on a position of the metal fixed core30, which attracts the metal movable core41, whereas the initial position of the movable valving element40is determined according to a position of the fixed valve seat200awith which the movable valving element40is engaged. Therefore, in order to secure accuracy in control of a flow of fluid in the fluid passage2,3002,4002through the opening and closing of the fluid passage2,3002,4002by use of the electromagnetic drive of the movable valving element40, it is important to make stable the relative position of the fixed valve seat200awith regard to the fixed core30to keep constant the separation distance between the attraction position and the initial position.

Based on such a finding, a linear expansion coefficient of the valve seat member20,3020,4020is made smaller than the resin body10,2010,3010,4010. Accordingly, thermal expansion of the valve seat member20,3020,4020can be limited. The valve seat member20,3020,4020is clamped axially between the first sealing member80,5802which is positioned around the fixed core30for sealing the fluid passage2,3002,4002, and the second sealing member90,4090for this sealing purpose. As a result, the valve seat member20,3020,4020can be positioned relative to the fixed core30via this first sealing member80,5802. Moreover, the elastic restoring force, which is larger than the force applied by the first sealing member80,5802in an elastic compression state, is applied by the second sealing member90,4090in an elastic compression state to the valve seat member20,3020,4020. The valve seat member20,3020,4020is thereby pressed on the first sealing member80,5802. Consequently, a variation in the operation of positioning the valve seat member20,3020,4020relative to the fixed core30is not easily made.

For these reasons, as for the valve seat member20,3020,4020thermal expansion of which is restrained and which is positioned relative to the fixed core30, a relative position of the fixed valve seat200awith respect to the fixed core30can be stabilized. Thus, even if the resin body10,2010,3010,4010having a high linear expansion coefficient is thermally-expanded, the fluctuation of a flow rate of fluid flowing through a clearance between the movable valving element40and the fixed valve seat200aat the attraction position can be curbed with the separation distance between the attraction position and the initial position being maintained. Accordingly, accuracy in control of a flow of fluid in the fluid passage2,3002,4002can be ensured.

The first sealing member80and the second sealing member4090may be annularly formed coaxially with each other inside the resin body4010.

The annular second sealing member4090generates the elastic restoring force which is larger than its coaxial annular first sealing member80in the entire circumferential direction. Consequently, a circumferential variation of the pressing pressure of the valve seat member4020against the first sealing member80can be reduced. As a result, the operation of positioning the valve seat member4020relative to the fixed core30can be enhanced so as to stabilize a relative position of the fixed valve seat200aof the valve seat member4020with respect to the fixed core30. Therefore, reliability in the effect of securing the accuracy in control of fluid circulation by limiting the fluctuation of a flow rate of fluid through a clearance between the fixed valve seat200aand the movable valving element40is improved.

The resin body10,2010,3010,4010may include: a resin housing11,2011,3011,4011that is formed from resin and accommodates therein the valve seat member20,3020,4020and the first and second sealing members80,5802;90,4090along with the fixed core30and the movable valving element40; and a resin cover12,3012,4012that is formed from resin and is joined to the resin housing11,2011,3011,4011. The second sealing member90,4090may be clamped between the resin cover12,3012,4012and the valve seat member20,3020,4020.

At the time of formation of the resin body10,2010,3010,4010, the resin cover12,3012,4012is joined to the resin housing11,2011,3011,4011in which the valve seat member20,3020,4020and the sealing members80,5802,90,4090together with the fixed core30and the movable valving element40are accommodated. Accordingly, the second sealing member90,4090of these sealing members80,5802,90,4090can be easily clamped between the resin cover12,3012,4012and the valve seat member20,3020,4020. As a result of such a clamping mode, the elastic restoring force, which is larger than the first sealing member80,5802, can be produced by properly elastically-compressing the second sealing member90,4090between the resin cover12,3012,4012and the valve seat member20,3020,4020. Hence, the operation of positioning the valve seat member20,3020,4020relative to the fixed core30reliably does not vary easily. As a consequence, a relative position of the fixed valve seat200aof the valve seat member20,3020,4020with respect to the fixed core30is stabilized. Therefore, reliability in the effect of securing the accuracy in control of fluid circulation by limiting the fluctuation of a flow rate of fluid through a clearance between the fixed valve seat200aand the movable valving element40is improved.

The first sealing member80,5802may be clamped between the resin body10,3010,4010and the valve seat member20,3020,4020around the fixed core30.

By clamping the first sealing member80,5802between the resin body10,3010,4010and the valve seat member20,3020,4020in the periphery of the fixed core30, not only the positioning of the first sealing member80,5802relative to the fixed core30but also the positioning of the valve seat member20,3020,4020relative to the fixed core30can be properly achieved via the first sealing member80,5802. Accordingly, a relative position of the fixed valve seat200aof the valve seat member20,3020,4020, which is positioned relative to the fixed core30, with respect to the fixed core30is stabilized. Therefore, a flow rate change, which deteriorates the accuracy in control of the fluid circulation, can be curbed through a clearance between the fixed valve seat200aand the movable valving element40.

The first sealing member80may be clamped between the fixed core30and the valve seat member20.

By clamping the first sealing member80between the fixed core30and the valve seat member20, the positioning of the valve seat member20relative to the fixed core30as well as the positioning of the first sealing member80relative to the fixed core30can be stably achieved via the first sealing member80. Accordingly, a relative position of the fixed valve seat200aof the valve seat member20, which is positioned relative to the fixed core30, with respect to the fixed core30is stabilized. Therefore, a flow rate change, which deteriorates the accuracy in control of the fluid circulation, can be reliably curbed through a clearance between the fixed valve seat200aand the movable valving element40.

The fluid control electromagnetic valve1,2001,3001,4001may be adapted to be connected between a fuel tank3that stores fuel and a canister4that adsorbs fuel vapor which is produced by evaporation of fuel in the fuel tank3. The fluid passage2,3002,4002may include: a passage portion2duthat is located on an upstream side of the fixed valve seat200ain a flow direction of fluid and is connected to the fuel tank3; and a passage portion2dlthat is located on a downstream side of the fixed valve seat200ain the flow direction of fluid and is connected to the canister4. The fluid may include a mixture of fuel vapor and air. The fluid control electromagnetic valve1,2001,3001,4001may control a flow of the mixture from the fuel tank3toward the canister4.

The passage portions2du,2dlof the fluid passage2,3002,4002on upstream and downstream sides of the fixed valve seat200aare connected to the fuel tank3which stores fuel, and the canister4which adsorbs fuel vapor produced by the evaporation of fuel in the tank3. Accordingly, a flow of the mixture of fuel vapor and air from the fuel tank3toward the canister4can be controlled. Because the relative position of the fixed valve seat200aof the valve seat member20,3020,4020with respect to the fixed core30can be stabilized as described above, the accuracy in control of circulation of the fuel-air mixture can be ensured.