Patent Publication Number: US-2015068617-A1

Title: Valve and fuel tank structure

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2013-189476, filed on Sep. 12, 2013, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are related to a valve and a fuel tank structure. 
     BACKGROUND 
     There are structures in which, when fuel is supplied to a fuel tank, a float rises and blocks a communication path from the fuel tank to the engine (see, for example, Japanese Laid-Open Patent Publication No. 09-264220). 
     In a structure in which a communication hole for communication with the engine is blocked by a float that rises within a fuel tank in this way, when pressure fluctuations from the engine are applied from the communication hole to the float, there is the concern that the float will move vertically and some sound may be generated. 
     SUMMARY 
     In a first aspect, a valve has: a float that is provided within a fuel tank and that, by floating in fuel, blocks a communication hole that communicates with an engine; a housing that accommodates the float within the fuel tank such that the float can move vertically, and into and from which fuel, that is within the fuel tank, enters and exits; and a dam member that is provided at the float, and that locally narrows a gap between the float and the housing. 
     In this valve, the float floats (rises) within the housing due to a rise in the liquid level within the fuel tank. Further, due to the communication hole that communicates with the engine being blocked by the float that has risen, flowing-out of vapor from the fuel tank is suppressed. 
     The dam member is provided at the float. Due to this dam member, the gap between the float and the housing is narrowed locally as compared with a structure that does not have this dam member. Accordingly, even if pressure from the engine is applied from the communication hole to the float, resistance is imparted by the dam member to vertical movement of the float. Due thereto, vertical movement of the float can be suppressed. 
     In a second aspect, in the first aspect, the valve further has: a fuel inflow port that is formed in the housing and through which fuel, that flows into the housing, passes; and a resistance member that, at least in a state in which the float blocks the communication hole, applies movement resistance to fuel that passes through the fuel inflow port. 
     Because the fuel inflow port is formed at the housing, the fuel that is within the fuel tank flows into the housing from the fuel inflow port. When the float floats and rises in the fuel that has flowed into the housing, the float blocks the communication hole. 
     This valve has the resistance member. At least in the state in which the float blocks the communication hole, the resistance member imparts movement resistance to the fuel that passes through the fuel inflow port. Accordingly, when the fuel attempts to pass through the fuel inflow port accompanying the vertical movement of the float, the resistance that is applied to this passage of fuel becomes large. Therefore, resistance to the vertical movement of the float also becomes large. 
     In a third aspect, in the second aspect, the resistance member includes a mesh member that is provided at the fuel inflow port. 
     By the simple structure of providing the mesh member at the fuel inflow port, the resistance member is structured and resistance can be imparted to the fuel that passes through the fuel inflow port. 
     In a fourth aspect, in the second aspect, the resistance member includes a cover member that moves vertically together with the float and that, by rising, blocks at least a portion of the fuel inflow port. 
     When the float rises, the cover member blocks at least a portion of the fuel inflow port. Therefore, resistance can be imparted to the fuel that passes through the fuel inflow port. 
     Further, at times when the float has not risen, the cover member opens the fuel inflow port greatly, and a structure in which resistance to the fuel, that passes through the fuel inflow port, is made to be low can be realized. 
     In a fifth aspect, in the fourth aspect, the cover member is molded integrally with the float. 
     By molding the cover member integrally with the float, the number of parts is lower than that of a structure in which the cover member is molded as a separate body. 
     In a sixth aspect, a fuel tank structure has: a fuel tank that accommodates fuel; and the valve of any one of the first aspect through the fifth aspect that is provided within the fuel tank and at a communication pipe that communicates the fuel tank and an engine. 
     In this fuel tank structure, when fuel is supplied into the fuel tank and the liquid level within the housing becomes higher than the buoyancy point of the float, the float floats in the fuel and rises. The fuel tank and the engine are communicated by the communication pipe. 
     Further, because the fuel tank structure has the valve of any one of the first aspect through the fifth aspect, even if pressure from the engine is applied to the float from the communication hole, vertical movement of the float can be suppressed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic structural drawing showing a fuel tank structure of a first embodiment of the present invention. 
         FIG. 2  is a vertical sectional view showing a valve of the first embodiment of the present invention. 
         FIG. 3  is a cross-sectional view along line  3 - 3  of  FIG. 2 , showing the valve of the first embodiment of the present invention. 
         FIG. 4  is a vertical sectional view showing the valve of the first embodiment of the present invention. 
         FIG. 5  is a vertical sectional view showing a valve of a second embodiment of the present invention. 
         FIG. 6  is a perspective view showing, partially and in an enlarged manner, the valve of the second embodiment of the present invention. 
         FIG. 7  is a vertical sectional view showing the valve of the second embodiment of the present invention. 
         FIG. 8  is a vertical sectional view showing a valve of a third embodiment of the present invention. 
         FIG. 9  is a schematic vertical sectional view showing a modified example of the valve of the present invention. 
         FIG. 10  is a schematic vertical sectional view showing a modified example of the valve of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A fuel tank structure  12  of a first embodiment of the present invention is shown in  FIG. 1 . Further, an ORVR (Onboard Refueling Vapor Recovery) valve  24 , that structures the fuel tank structure  12 , and the vicinity thereof are shown in a cross-sectional view in  FIG. 2 . The ORVR valve  24  is an example of the “valve” relating to the present application. 
     The fuel tank structure  12  has a fuel tank  14  that can accommodate fuel at the interior thereof. The lower end portion of an inlet pipe  16  is connected to the upper portion of the fuel tank. The opening portion at the upper end of the inlet pipe  16  is a fueling port  16 H. A fueling gun is inserted in the fueling port  16 H, and fueling of the fuel tank  14  can be carried out. The fueling port  16 H of the inlet pipe  16  is usually opened and closed by a fuel cap  26 , and, at times of fueling, the fuel cap  26  is removed by the fueling operator or the like. 
     A canister  18  is provided at the exterior of the fuel tank  14 . An adsorbent such as active carbon or the like is accommodated at the interior of the canister  18 . The vapor layer at the interior of the fuel tank  14  and the canister  18  are connected by a communication pipe  20 . A sealing valve  48  is provided midway along the communication pipe  20 . The sealing valve  48  is an electromagnetic valve in the present embodiment, and the opening and closing thereof are controlled by a control device. 
     In the state in which the sealing valve  48  is open, the vapor within the fuel tank  14  can move through the communication pipe  20  to the canister  18 , but, in the state in which the sealing valve  48  is closed, this movement of vapor is not possible. The evaporated fuel within the vapor that has moved to the canister  18  is adsorbed by the adsorbent of the canister  18 , and the vapor (the atmosphere component) other than the evaporated fuel is discharged into the atmosphere from an atmosphere communication pipe  22 . 
     The canister  18  and an engine  28  are connected by a purge pipe  40 . Due to negative pressure of the engine  28  being applied to the canister  18  in the state in which the sealing valve  48  is closed, atmospheric air is introduced-in from the atmosphere communication pipe  22 , and the evaporated fuel that has been adsorbed by the adsorbent can be released (purged). The evaporated fuel that is released is sent to and combusted at the engine  28 . 
     The ORVR valve  24  is provided at the lower end of the communication pipe  20  to as to be positioned at the upper portion of the interior of the fuel tank  14 . The ORVR valve  24  is a so-called float valve and has, within a valve housing  42 , a float  44  that floats in fuel FE. 
     As shown in detail in  FIG. 2 , the valve housing  42  of the ORVR valve  24  has a housing main body  50  and a housing bottom plate  52 . The housing main body  50  is substantially cylindrical tube shaped, and the bottom portion thereof is open. The housing bottom plate  52  is installed at the bottom portion of this housing main body  50 . The upper portion of the housing main body  50  is positioned further upward than a ceiling plate  14 T of the fuel tank  14 , and is a connection portion to which the communication pipe  20  (see  FIG. 1 ) is connected. 
     A partitioning wall  54 , that partitions the interior of the housing main body  50  vertically, is formed at the housing main body  50 . A communication hole  56 , that makes the inner diameter of the housing main body  50  small locally, is formed in the partitioning wall  54 . Further, the float  44 , that is substantially solid cylindrical or substantially cylindrical tube shaped, is accommodated between the partitioning wall  54  and the housing bottom plate  52 . 
     A valve seat  58  that is annular is installed at the upper portion of the float  44 . The closed-valve state shown in  FIG. 5  arises due to the float  44  approaching the partitioning wall  54  (rising in the example of  FIG. 2 ) and the valve seat  58  contacting (tightly fitting to) the partitioning wall  54  at the periphery of the communication hole  56 . In the closed-valve state, the communication hole  56  is blocked, and movement of vapor from the interior of the fuel tank  14  to the canister  18  is impeded. In contrast, the state in which the valve seat  58  has moved away from the partitioning wall  54  is the open-valve state that is shown in  FIG. 2 . In the open-valve state, vapor can move through the communication hole  56 . 
     Plural ribs  46  are formed at the inner peripheral surface of the housing main body  50 , further downward than the partitioning wall  54  at the valve housing  42 . The respective ribs  46  extend in the vertical direction. As shown in  FIG. 3  as well, the plural ribs  46  are disposed at a predetermined interval in the peripheral direction of the valve housing  42 . Distal ends  46 T of the ribs  46  face the outer peripheral surface of the float  44  with a slight gap therebetween. Due thereto, the ribs  46  suppress lateral shifting and rattling at the time when the float  44  moves vertically, and guide the vertical movement of the float  44 . 
     A spring  60  is disposed between the float  44  and the housing bottom plate  52 . The spring  60  applies spring force in the valve-closing direction (upward in the example of  FIG. 2 ) to the float  44 . 
     As shown in  FIG. 2 , in a state in which fuel does not exist within the valve housing  42 , spring force in the valve-closing direction (upward) is applied from the spring  60  to the float  44 . However, because the gravitational force of the float  44  is greater, the float  44  is in the open-valve state. Further, even if fuel does exist within the valve housing  42 , in a state in which the liquid level is lower than a float buoyancy liquid level FL (details of which are described later), the resultant force of the spring force of the spring  60  and the buoyancy from the fuel is lower than the gravitational force applied to the float  44 . Therefore, the float  44  does not move in the valve-closing direction, and is in the open-valve state. 
     In contrast, when the liquid level within the valve housing  42  becomes equal to or higher than the float buoyancy liquid level FL, the resultant force of the spring force of the spring  60  and the buoyancy from the fuel becomes greater than the gravitational force that is applied to the float  44 , and the float  44  enters into the closed-valve state. 
     Note that, when the ORVR valve  24  is turned upside-down, the gravitational force applied to the float  44  and the spring force from the spring  60  are both in the valve-closing direction, and become greater than the buoyancy from the fuel that is applied to the float  44 . Therefore, the float  44  enters into the closed-valve state, and flowing-out of fuel from the fuel tank  14  is suppressed. 
     One or plural flow-out holes  62  are formed in the housing bottom plate  52 . The fuel within the valve housing  42  passes through the flow-out holes  62  and flows-out to the exterior of the valve housing  42  (into the interior of the fuel tank  14 ). 
     A fuel inflow port  64  is formed in the peripheral wall of the housing main body  50 . Fuel within the fuel tank  14  passes through the fuel inflow port  64  and enters into and exits from the interior of the valve housing  42 . 
     In the present embodiment, the lower end of the fuel inflow port  64  is formed at a position higher than the float buoyancy liquid level FL (however, is formed at a height that is positioned within the fuel tank  14  and lower than the partitioning wall  54 ). Accordingly, in a case in which the fuel FE is at a liquid level that is equal to or higher than the float buoyancy liquid level FL within the valve housing  42 , even if the fuel FE flows-out from the fuel inflow port  64 , the liquid level becoming lower than the float buoyancy liquid level FL is suppressed. However, in a case in which the fuel FE is at a liquid level that is beneath the float buoyancy liquid level FL, the fuel passes through the flow-out holes  62  and flows-out from the valve housing  42 . 
     In contrast, the opening surface area of the flow-out holes  62  in the present embodiment is made to be small so that the float  44  will not fall in a short period of time at the time of fueling. Due thereto, a period of time in which fuel exists within the valve housing  42  can be sufficiently ensured. Further, in a state in which the liquid level within the fuel tank  14  is at a position that is lower than the flow-out holes  62  for example, fuel within the valve housing  42  gradually flows-out from the flow-out holes  62  into the fuel tank  14 . 
     As shown in detail in  FIG. 2  through  FIG. 4 , a dam member  66  extends out toward the radial direction outer side from the outer periphery of the float  44 . The dam member  66  locally narrows a gap G1 between the float  44  and the valve housing  42 . In other words, when seen along the direction of vertical movement of the float  44 , the cross-sectional area of the float  44  is locally large as compared with a structure that does not have the dam member  66 . Further, in a case in which the float  44  attempts to move vertically in the state in which fuel exists at the periphery of the dam member  66 , not only the float  44 , but also the dam member  66  hits the fuel. Because the region of passage of the fuel at the time when the float  44  attempts to move vertically is narrow, resistance is applied to the movement of fuel at this region of passage. Namely, in the present embodiment, resistance to vertical movement of the float  44  is large as compared with a structure that does not have the dam member  66 . 
     There may be a structure in which the dam member  66  is formed as a body separate from the float  44  and is mounted to the float  44 . However, in the present embodiment, the dam member  66  is molded integrally with the float  44 , and an increase in the number of parts is suppressed. 
     Further, in the present embodiment, the dam member  66  is made into a shape that is continuous in the peripheral direction of the float  44 , but the dam member  66  may be a shape that is discontinuous in the peripheral direction of the float  44 . 
     A mesh member  68  is attached to the housing main body  50  so as to cover the fuel inflow port  64 . In the present embodiment, the mesh member  68  is structured by a fabric-like member such as a woven fabric or a non-woven fabric or the like, and covers the entirety of the fuel inflow port  64  from the outer side of the housing main body  50 . When fuel moves through the fuel inflow port  64 , the fuel passes through the minute holes of the mesh member  68 . Therefore, the resistance to movement of the fuel is large as compared with a structure that does not have the mesh member  68 . The mesh member  68  is an example of the resistance member. 
     Operation of the fuel tank structure  12  of the present embodiment is described next. 
     In the state before fuel is supplied to the fuel tank  14 , fuel does not exist within the valve housing  42  of the ORVR valve  24 , and the float  44  is in the open-valve state as shown in  FIG. 2 . Because vapor within the fuel tank  14  moves from the communication pipe  20  to the canister  18 , fuel can be supplied to the fuel tank  14  continuously. 
     When fuel is supplied into the fuel tank  14  and the liquid level of the fuel that has flowed into the valve housing  42  becomes equal to or higher than the float buoyancy liquid level FL, the float  44  enters into the closed-valve state as shown in  FIG. 4 . The communication hole  56  is blocked, and vapor within the fuel tank  14  no longer flows from the communication pipe  20  to the canister  18 . Therefore, the fuel that is supplied rises within the inlet pipe  16  and reaches the fueling gun. Then, the auto-stop mechanism of the fueling gun activates, and fueling of the fuel tank  14  is stopped. 
     When the sealing valve  48  opens in the state in which fuel is not being supplied to the fuel tank  14 , pressure of the engine  28  passes through the purge pipe  40  and is applied to the canister  18 . For example, negative pressure from the engine  28  acts on the canister  18 , and the canister  18  can be purged. 
     Some of the pressure (the negative pressure and the positive pressure) that is applied from the engine  28  to the canister  18  is applied, through the communication pipe  20 , to the ORVR valve  24 . In particular, there are cases in which fluctuations in this pressure act on the float  44  as force that causes vertical movement (vibration). 
     At the ORVR valve  24  of the present embodiment, the dam member  66  is formed at the float  44 , and the gap G1 between the float  44  and the valve housing  42  is narrowed locally. When the float  44  moves vertically, the resistance that is applied to the vertical movement of the float  44  is large as compared with a structure that does not have the dam member  66 . Due thereto, vertical movement of the float  44  can be suppressed. In particular, vibration of the float  44  in cases in which pulsation of the pressure from the engine  28  arises (in cases in which negative pressure and positive pressure are applied repeatedly) can be suppressed. 
     Furthermore, at the ORVR valve  24  of the first embodiment, the mesh member  68  is attached to the fuel inflow port  64 . When fuel moves through the fuel inflow port  64 , large movement resistance is applied thereto as compared with a structure that does not have the mesh member  68 . Because entering and exiting of the fuel, that is within the valve housing  42 , through the fuel inflow port  64  is suppressed, the fuel that is within the valve housing  42  can be used effectively as resistance to vertical movement of the float  44 . Namely, fuel that is within the valve housing  42  is made to work as a damper on the vertical movement of the float  44 . Therefore, vertical movement of the float  44  can be suppressed more effectively. 
     Further, by suppressing vertical movement of the float  44 , even in cases in which the float  44  is in a vicinity of the blocking position for example, the occurrence of abnormal sound that is due to vertical movement of the float  44  also can be suppressed. 
     Further, in the present embodiment, the fuel inflow port  64  is positioned further upward than the float buoyancy liquid level FL, and in addition, the opening cross-sectional areas of the flow-out holes  62  are made to be small so that the period of time over which fuel exists within the valve housing  42  can be ensured sufficiently. Accordingly, fuel flowing-out to beneath the float buoyancy liquid level FL within the valve housing  42  can be suppressed as compared with a structure in which the fuel inflow port  64  is positioned further downward than the float buoyancy liquid level FL or a structure in which the flow-out holes  62  are large. 
     Further, it is easy to maintain the state in which fuel, that is necessary to maintain the state in which the float  44  is floating in the fuel, exists within the valve housing  42 , and the effect of suppressing vertical movement of the float  44  is strong. 
     A second embodiment is described next. An ORVR valve  74  of the second embodiment is shown in  FIG. 5 . In the second embodiment, structural elements, members and the like that are the same as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the second embodiment, the overall structure of the fuel tank structure is similar to that of the first embodiment, and therefore illustration thereof is omitted. 
     The ORVR valve  74  of the second embodiment has, as an example of the resistance member, a cover member  76  instead of the mesh member  68  of the first embodiment. 
     As shown in detail in  FIG. 6  as well, the cover member  76  has a laterally extending portion  78 , an upwardly extending portion  80 , and a cover main body portion  82 . The laterally extending portion  78  extends from the float  44  toward the radial direction outer side. The upwardly extending portion  80  extends upward from the distal end of the laterally extending portion  78 . The cover main body portion  82  is substantially disc-shaped, and is provided at the distal end (the upper end) of the upwardly extending portion  80 . 
     A through-hole  84  is formed in the housing main body  50 . The laterally extending portion  78  passes through the through-hole  84 . In the peripheral direction of the housing main body  50 , the gaps between the through-hole  84  and the laterally extending portion  78  are set to be small. Due thereto, when the float  44  rotates in the peripheral direction, the laterally extending portion  78  contacts the inner surface of the through-hole  84 , and acts as a rotation stopper that limits rotation of the float  44 . 
     In contrast, the height of the through-hole  84  is made to be larger than the height of the laterally extending portion  78 . Due thereto, vertical movement of the cover member  76 , that accompanies vertical movement of the float  44 , is permitted. Further, when the float  44  is in the opening state, as shown in  FIG. 5 , the cover main body portion  82  opens a portion of the fuel inflow port  64 . In contrast, the shapes and the positions of the cover member  76  and the through-hole  84  are set such that, when the float  44  is in the blocking state, as shown in  FIG. 7 , the cover main body portion  82  covers the fuel inflow port  64  from the outer side. 
     Also in the ORVR valve  74  of the second embodiment that has such a structure, in a case in which some of the pressure of the engine  28  acts on the ORVR valve  74 , the resistance to vertical movement of the float  44  increases due to the dam member  66 . Further, vertical movement of the float  44  is suppressed. 
     In the ORVR valve  74  of the second embodiment, when the float  44  is in the blocking state, the cover member  76  covers the fuel inflow port  64 . Therefore, large movement resistance is applied to movement of the fuel as compared with a structure in which the fuel inflow port  64  is not covered. Because entering and exiting of the fuel, that is within the valve housing  42 , through the fuel inflow port  64  is suppressed, the fuel that is within the valve housing  42  can be effectively used as resistance to vertical movement of the float  44 , and vertical movement of the float  44  can be suppressed. Note that, in the second embodiment, when the float  44  is in the opening state, a portion of the fuel inflow port  64  is not covered by the cover member  76 , and therefore, there is little effect on the entering and exiting of fuel into and from the valve housing  42 . 
     Furthermore, in the same way as in the ORVR valve  24  of the first embodiment, the fuel inflow port  64  is positioned further upward than the float buoyancy liquid level FL, and the opening cross-sectional areas of the flow-out holes  62  are made to be small. Therefore, it is easy to maintain the state in which fuel exists within the valve housing  42 , and the effect of suppressing vertical movement of the float  44  is strong. 
     A third embodiment is described next. An ORVR valve  94  of the third embodiment is shown in  FIG. 8 . In the third embodiment, structural elements, members and the like that are the same as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the third embodiment, the overall structure of the fuel tank structure is similar to that of the first embodiment, and therefore illustration thereof is omitted. 
     The ORVR valve  94  of the third embodiment has, as an example of the resistance member, a cover member  96  instead of the mesh member  68  of the first embodiment or the cover member  76  of the second embodiment. 
     The cover member  96  is formed as a convex portion at which the outer peripheral surface of the float  44  is projected-out locally toward the radial direction outer side. The shape and the position of the cover member  96  are set such that, when the float  44  is in the opening state, the cover member  96  opens a portion of the fuel inflow port  64  as shown by the solid line in  FIG. 8 , whereas, when the float  44  is in the blocking state, the cover member  96  covers the fuel inflow port  64  from the inner side as shown by the two-dot chain line in  FIG. 8 . 
     Also in the ORVR valve  94  of the third embodiment that has such a structure, in a case in which some of the pressure of the engine  28  acts on the ORVR valve  94 , the resistance to vertical movement of the float  44  increases due to the dam member  66 , and vertical movement of the float  44  is suppressed. 
     In the ORVR valve  94  of the third embodiment, when the float  44  is in the blocking state, the cover member  96  covers the fuel inflow port  64 , and therefore, large movement resistance is applied as compared with a structure in which the fuel inflow port  64  is not covered. Because entering and exiting of the fuel, that is within the valve housing  42 , through the fuel inflow port  64  is suppressed, the fuel that is within the valve housing  42  is effectively used as resistance to vertical movement of the float  44 , and vertical movement of the float  44  can be suppressed. Note that, also in the third embodiment, when the float  44  is in the opening state, a portion of the fuel inflow port  64  is not covered by the cover member  96 , and therefore, there is little effect on the entering and exiting of fuel into and from the valve housing  42 . 
     Moreover, in the same way as in the ORVR valve  24  of the first embodiment, the fuel inflow port  64  is positioned further upward than the float buoyancy liquid level FL, and the opening cross-sectional areas of the flow-out holes  62  are made to be small. Therefore, it is easy to maintain the state in which fuel exists within the valve housing  42 , and the effect of suppressing vertical movement of the float  44  is strong. 
     Embodiments of the present invention have been described above, but the dam member of the present invention is not limited to the above-described structure. In other words, it suffices to make the surface area in the direction of vertical movement of the float  44  large and to generate greater resistance to the vertical movement, by locally narrowing the gap between the float  44  and the valve housing  42 . For example, as shown in  FIG. 9 , the dam member may be a dam member  102  that extends-out toward the radial direction outer side from an intermediate portion (a portion that is not the lower end) in the height direction at the float  44 . Moreover, as shown in  FIG. 10 , a projecting member  104  may be made to project-out downward from the bottom portion of the float  44 , and the dam member may be a dam member  106  that is structured so as to extend-out toward the radial direction outer side from this projecting member. If the projecting member  104  is formed in a solid cylindrical shape for example, the spring  60  (see  FIG. 2 ) can be accommodated at the interior of the projecting member  104 . 
     In the present application, even if pressure from the engine is applied to the float from the communication hole, vertical movement of the float can be suppressed. 
     The disclosure of Japanese Patent Application No. 2013-189476 that was filed on Sep. 12, 2013 is, in its entirety, incorporated by reference into the present specification. 
     All cited documents, patent applications and technical standards mentioned in the present specification are incorporated by reference in the present specification to the same extent as if the individual cited documents, patent applications and technical standards were specifically and individually incorporated by reference in the present specification.