Sound-absorbing device and its mounting method

The degree of freedom of a sound-absorbing device in terms of size is increased, maintaining easy mounting operation of the sound-absorbing device, even if the sound-absorbing device has a greater length.The sound-absorbing device 1, which alleviates and absorbs a sound generated by fuel movement in a fuel tank in such a state that the sound-absorbing device is put into the tank through an opening E formed in the tank and is mounted to the tank, has a three-dimensional structure, which has a narrower width X than a width of the opening and a greater length Y than the width of the opening E; and the sound-absorbing device comprising plural sound-absorbing parts 2A and 2B coupled together through a coupling portion 3 in an intermediate position in a longitudinal direction extending along the length Y.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a sound-absorbing device, which is mounted to the inside of a fuel tank to alleviate and absorb the sound of liquid accompanied by fuel movement inside thereof, and a method for mounting the same.

2. Background Art

A fuel tank has a sound-absorbing device mounted to the inside thereof to alleviate and absorb the sound of liquid accompanied by fuel movement inside thereof. Such a sound-absorbing device may have various kinds of structures.FIGS. 17(a) and (b) show an example of the fuel tank, which has been disclosed in Patent Document 1,FIG. 17(a) is a perspective view of the fuel tank, andFIG. 17(b) is a cross-sectional view taken along line a-a ofFIG. 17(a). The shown fuel tank has a tank body T integrally formed therewith by blow molding, includes, e.g. an opening E for attachment of a unit gauge and has stays S disposed at plural positions therein. Sound absorbing devices (baffles)100, each of which has mounting holes101formed therein to pass therethrough in a thickness direction thereof, are fixed to the fuel tank by being put into the tank through the opening E, followed by inserting stays S in the mounting holes and disposing clips C on projection edges of the stays S.Patent Document 1: Japanese Patent No. 3555335

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

The above-described conventional sound-absorbing devices100are subjected to limitations to width and length because of being put into the tank through, e.g. the opening E for attachment of a unit gauge and being positioned inside the tank. For example, as the thickness of a tank decreases, it becomes more difficult to mount such sound-absorbing devices to the tank since the sound-absorbing devices are more highly likely to be brought into conflict with the bottom of the tank when being put into the tank through the opening. For this reason, the problem has been dealt with by limiting the length of such sound-absorbing devices and increasing the number of the sound-absorbing devices to be mounted.

It is an object of the present invention to solve the above-mentioned problem and to provide a sound-absorbing device, which is capable of increasing the degree of freedom in the size thereof, maintaining an easy mounting operation of the sound-absorbing device and having an excellent sound-absorbing property even if the sound-absorbing device has a greater length, and a method for mounting the same.

Means for Solving the Problems

In order to attain the above-mentioned object, the present invention provides the following solutions:

According to a first aspect of the present invention, there is provided a sound-absorbing device, which is adapted to alleviate and absorb a sound generated by fuel movement in a fuel tank in such a state that the sound-absorbing device is put into the tank through an opening formed in the tank and is mounted to the tank; having a three-dimensional structure, which has a narrower width than a width of the opening and a greater length than the width of the opening; and the sound-absorbing device comprising plural sound-absorbing parts coupled together through a coupling portion in an intermediate position in a longitudinal direction extending along the length.

In the sound-absorbing device according to the present invention, it is preferred that the plural sound-absorbing parts be configured not only to be swingable between a first state and a second state through the coupling portion and that the plural sound-absorbing parts include a retainer, which is configured to selectively maintain the plural sound-absorbing parts in the first state and the second state so as to prevent the plural sound-absorbing parts from swinging; that the retainer be configured to prevent the plural sound-absorbing parts from swinging in conjunction with an operation, by which the plural sound-absorbing parts are selectively set in the first state and the second state through the coupling portion; that the retainer be configured to also serve as the coupling portion; that the sound-absorbing device further have an engageable portion formed therewith so as to be engageable with a stud projecting into the fuel tank; or that the engageable portion be configured to absorb variations in a projecting position of the stud.

According to a second aspect of the present invention, there is provided a method for mounting a sound-absorbing device, which is adapted to alleviate and absorb a sound generated by fuel movement in a fuel tank in such a state that the sound-absorbing device is put into the tank through an opening formed in the tank and is mounted to the tank; comprising a swinging step where the sound-absorbing device is swung about an intermediate portion thereof in a longitudinal direction thereof to be set in a first state; an inserting step where the sound-absorbing device is put into the tank through the opening, maintaining the first state; a re-swinging step where the sound-absorbing device is set from the first state to a second state to be ready for use in the tank; and a mounting step where the sound-absorbing device is mounted inside the tank.

In the method according to the present invention, it is preferred that the mounting step be conducted so as to be continuous to the re-swinging step where the sound-absorbing device is swung to the second state.

Effects of the Invention

In accordance with the first aspect of the present invention, the sound-absorbing device is formed of the plural sound-absorbing parts coupled together through the coupling portion in such an intermediate position in the longitudinal direction extending along the length. Thus, it is possible to improve the operation for mounting the sound-absorbing device inside the tank and to make the sound-absorbing device adaptable to tanks having different shapes by coupling the plural sound-absorbing parts to have an angle therebetween so as to easily put the plural sound-absorbing parts into the tank or by forming the plural sound-absorbing parts as a main part and a sub-part as shown as examples in the embodiments. It is possible to provide the sound-absorbing device with a sound-absorbing property set to be optimum to the shape of a tank by modifying the coupling angle of the main part and the sub-part (such as the extending directions of the sound-absorbing parts) as shown in a second embodiment.

The sound-absorbing device according to the present invention can reliably secure its optimum sound-absorbing property by utilizing the retainer to prevent the plural sound-absorbing parts from swinging with the plural sound-absorbing parts keeping a preferred state (the first state or the second state) to obtain an optimum sound-absorbing property, for example. When the retainer is configured to prevent the plural sound-absorbing parts from swinging in conjunction with an operation, by which the plural sound-absorbing parts are set in such a preferred state in order to obtain an optimum sound-absorbing property in the tank after the sound-absorbing device is put into fuel tank, it is possible to improve the mounting operation in the fuel tank.

In the sound-absorbing device according to the present invention, when the retainer is configured to also serve as the coupling portion, it is possible to simplify the sound-absorbing device in comparison with a case where the retainer and the coupling portion are separately disposed in the sound-absorbing device. When the sound-absorbing device is mounted with the engageable portion being engaged with a stud in the fuel tank, it is possible not only to eliminate a member serving as a conventional clip but also to easily obtain an easy mounting operation for example. When the sound-absorbing device is configured to be mounted even if the projecting position of a stud is deviated from a designed position, it is possible to alleviate, e.g. the accuracy required for the mounting position of a stud and to reduce the occurrence of defective products.

In the mounting method accordance with the second aspect of the present invention, even if the sound-absorbing device has a greater length than the conventional devices, it is possible to maintain an excellent operation for insertion into a fuel tank and to obtain an excellent sound-absorbing property in a state with the sound-absorbing device being mounted (ready for use). When the mounting step is conducted so as to be continuous to the step where the sound-absorbing device is swung to the second state in the re-swinging step, it is possible to improve the operation for mounting the sound-absorbing device.

BEST MODE FOR CARRYING OUT THE INVENTION

The sound-absorbing devices according to embodiments of the present invention will be described in reference to accompanying drawings.FIG. 1toFIG. 8(b) show a first embodiment of the present invention, andFIG. 9toFIG. 16(d) show a second embodiment of the present invention. Now, the structure of the device according to the first embodiment, the method for mounting the device according to the first embodiment, the structure of the device according to the second embodiment, and the method for mounting the device according to the second embodiment will be described in this order.

First Embodiment

The sound-absorbing device1shown inFIG. 1toFIG. 8(b) is put into a tank through an opening E formed in a tank body T forming the tank and is fitted to studs9disposed to project into the tank. The sound-absorbing device has a three-dimensional structure, which has a narrower width X than the width of the opening E (hereinbelow, referred to as a short side acceptable into the opening E when the three-dimensional structure is divided into portions extending in short and long axes) and a greater length Y than the width of the opening E (hereinbelow, referred to as a long side unacceptable into the opening E when the three-dimensional structure is divided into the portions extending in the short and long axes), wherein the sound-absorbing device is formed of sound-absorbing parts2A and2B coupled together through a hinge3and a retainer4in a longitudinal direction extending along the length Y, the hinge and the retainer serving as a coupling portion. In other words, the sound-absorbing device1is formed in a three-dimensional structure having a greater length Y than the width of the opening E and is formed of sound-absorbing parts2A and2B, which are coupled together at an intermediate position of the sound-absorbing device in a longitudinal direction along the length so as to be swingable between a first state and a second state through a hinge3and are configured to selectively maintain the first state and the second state so that the sound-absorbing parts are prevented from swinging by a retainer4.

The tank body T is formed of a resin-molded article, which is formed by blow molding as in the tank disclosed in Patent Document 1. The tank body has the opening E for attachment of a unit gauge or a similar opening formed therein. The tank body T has a wall formed with the plural studs9projecting therefrom for attachment of the sound-absorbing device1. As shown inFIG. 2(b), each of the studs9has a head9a, a shaft9band plural elastic engageable blades9cintegrally formed therewith, the head being adapted to be fixed to an outer side of the wall by, e.g. welding, the shaft projecting from the head and extending into the tank through a through hole formed in the wall, and the elastic engageable blades being disposed on the shaft at substantially equal distances in a region from an intermediate portion of the shaft9bto a leading edge of the shaft.

Each of the sound-absorbing parts2A and2B is formed in a substantially reversed L-character shape in vertical section. The sound-absorbing part2A serves as a main part, being formed of a horizontal plate10and a vertical plate20. The sound-absorbing part2B serves as a sub-part, being formed of a horizontal plate25and a vertical plate26. Each of the horizontal plate10and the vertical plate20, and every portion of the sound-absorbing part2B are formed of a resin-molded article made of, e.g. a POM resin (polyacetal resin).

As shown inFIG. 4andFIGS. 7(a) and (b), the horizontal plate10of the sound-absorbing part2A has depressions formed in both ends in the longitudinal direction and has a connecting member11disposed on a rear side of the sound-absorbing part2A so as to extend longitudinally, the connecting member11having two engageable projections12formed on an outer side thereof. The horizontal plate10has plural through holes13formed therein, except for the depression on both ends, so as to pass therethrough, plural projections14projecting from a lower side thereof and an upright wall17projecting along an upper front edge. The horizontal plate two tubular portions15A and15B, guiding recessed portions16A and16B, and a lateral wall18integrally formed therewith, the two tubular portions projecting downward from the respective depressions formed in both ends, the guiding recessed portions being recessed in the width direction of a top side of the horizontal plate so as to correspond to the top open ends of the two tubular portions, and the lateral wall being disposed at a connection side of the horizontal plate with the sound-absorbing part2B. Reference symbols10ato10ddesignate reinforcing ribs. On the other hand, the vertical plate20has two frames21projecting from a front side thereof. The vertical plate is coupled with the horizontal plate10, having the frames21receiving the corresponding engageable projections12with the projections elastically engaged with engageable holes22formed in the frames21. The vertical plate20has plural through holes23, plural projections24and a connecting frame20aintegrally formed therein, the through holes passing through the vertical plate from both front and rear sides of the vertical plate, the projections projecting from the front side of the vertical plate, and the connecting frame disposed at a connection side of the vertical plate with the sound-absorbing part2B. The connecting frame is engaged with a projection18adisposed on the lateral wall18in such a state that the horizontal plate10and the vertical plate20are coupled together by engagement between the engageable projections12and the engageable holes22.

The through holes13and23are formed as small circular holes having the same diameter as one another at substantially equal distances in a left-to-right direction and a front-to-rear direction of the horizontal plate and in a left-to-right direction and a vertical direction of the vertical plate. The projections14and24are formed at substantially equal distances in the left-to-right direction and the front-to-rear direction of the horizontal plate and in the left-to-right direction and the vertical direction of the vertical plate so that a single through hole13or23is surrounded by four projections14or24. Although each of the projections14and24is formed in a hollow conical shape in the shown embodiment, it is sufficient that each of the projections is formed in a tapered shape so as to be gradually narrower toward the leading edge. The projections14and24may have a height properly set. The through holes and the projections are adopted based on test results showing that it is preferred to dispose such through holes and such projections in terms of effective dispersion or attenuation of a liquid sound, i.e. the energy of a liquid sound.

Each of the tubular portions15A and15B is formed as a rectangular frame in transverse section. Each of the tubular portions has engageable strips19integrally formed on the inner wall thereof as shown inFIG. 7(b). In each of the tubular portions, the engageable strips19are formed to project downward from opposed surfaces on the inner wall in a width direction of the rectangular frame. The tubular portion15A is formed so as to have a greater length than the tubular portion15B in the longitudinal direction as shown inFIG. 5. The engageable strips19of the tubular portion15A are formed so as to have a greater width accordingly. By this arrangement, even if the position of a stud9or the distance between adjacent studs9slightly deviates from a designed value, it is possible to insert studs9into the corresponding tubular portions15A and15B from the top ends of the tubular portions toward the lower ends of the tubular portions.

The recessed guiding portions16A and16B are formed so as to pass over the inlets of the tubular portions15A and15B and are defined by stepped walls16cand16c, and projecting ribs16d,16edisposed so as to face the respective stepped walls as seen fromFIG. 3(b) andFIG. 5. The recessed guiding portion16A has the rib16dobliquely disposed so as to have a greater width toward a front side therein. By this arrangement, when the sound-absorbing part2A is put into the tank body and is mounted to the tank in an invisible state, the studs9are allowed to be easily guided into the corresponding tubular portions15A and15B by the recessed guiding portions and the ribs16e. The upright wall17is a rib, which serves to position the sound-absorbing part2A so as to keep a gap between the sound-absorbing part and a mounting wall of the tank body.

On the other hand, the horizontal plate25of the sound-absorbing part2B corresponds to the horizontal plate10and includes lateral walls25aand25b, plural connecting strips25cand plural through holes27, the lateral walls projecting downward from both ends of the horizontal plate, the connecting strips being integrally formed with the vertical plate26so as to keep a gap on a rear side, and the through holes passing through the horizontal plate from both top and bottom sides of the horizontal plate. The vertical plate26corresponds to the vertical plate20and includes plural through holes28, plural projections29and other members, the through holes passing through the vertical plate from both front and rear sides of the vertical plate, the projections projecting from the front side.

The hinge3and the retainer4are disposed between the lateral wall18of the sound-absorbing part2A and the lateral wall25aof the sound-absorbing part2B, the hinge3and the retainer4being set in an upper position and a lower position, respectively as shown inFIGS. 8(a) and (b). As shown inFIG. 5andFIGS. 8(a) and (b), the hinge3is formed of three support ribs30,31and30formed thereon at equal distances in a width direction of the lateral wall18so as to project from the lateral wall18, shafts34disposed between one of the support ribs30and the support rib31and between the remaining support rib30and the support rib31, and hooks35, which are disposed on the lateral wall25aso as to be swingably engaged with the shafts34. By the hinge constructed as described above, it is possible to swing the sound-absorbing part2A and the sound-absorbing part2B by a certain angle (an angle of substantially 90 degrees in the shown embodiment) as shown inFIGS. 3(a) to (c). For example, it is possible to swingably set the sound-absorbing part2B from the first state where the sound-absorbing part2B is swung upwardly at an angle of substantially 90 degrees with respect to the sound-absorbing part2A to the second state where the sound-absorbing part2B is set in alignment with the sound-absorbing part2A so as to be ready for use by utilizing a reaction force caused when the sound-absorbing part2B is brought into contact with an inner wall of the tank.

The retainer4is formed of a first engageable portion40and a second engageable portion42projecting from the lateral wall18, and a first retaining portion45and a second retaining portion47disposed on the lateral wall25aso as to be engageable with and disengageable from the first engageable portion40and the second engageable portion42, respectively, as shown inFIG. 5andFIGS. 8(a) and (b). It should be noted that the engageable portions40and42, and the retaining portions45and47are shown as seen from above in the enlarged views inFIG. 8(b). Specifically, the first engageable portion40is formed in such a substantially U-character shape as to project from the lateral wall18and has a pawl41formed thereon inside of such a substantially U-character shape so as to project downward. The second engageable portion42is located behind the first engageable portion40and is formed in a plate shape projecting from the lateral wall18, having a pawl43formed on a leading edge thereof so as to project forward. On the other hand, the first retaining portion45is formed in a substantially rectangular frame shape projecting from the lateral wall25a. When the first engageable portion40is inserted into such a rectangular frame shape with the pawl41being displaced in a retracting direction, the first engageable portion is engaged with a front end forming a lower recess46in such a rectangular frame shape with the pawl41being returned to its original state. The second retaining portion47has a pawl48formed as a vertical rib on a leading edge behind such a rectangular frame shape so as to be engageable with and disengageable from the pawl43. When the second engageable portion42is brought close to the second retaining portion and has the pawl43climbing over the pawl48by utilizing elastic deformation, the second retaining portion47is engaged with the second engageable portion42. In this arrangement, the first engageable portion40and the second engageable portion42form the retainer together with the first retaining portion45and the second retaining portion47in order to set the sound-absorbing part2A and the sound-absorbing part2B in substantially alignment with each other. Further, both engageable portions and both retaining portions play as stoppers to make it difficult for the respective engageable portions40and42to engage with the corresponding retaining portions45and47when the second engageable portion42is brought into contact with the leading edge of the second retaining portion47at the time of putting the sound-absorbing device according to the present invention into the tank. The retainer4may be formed of retaining portions45and47disposed on the lateral wall18, and engageable portions40and42disposed on the lateral wall25a.

The above-mentioned sound-absorbing device1is put into the tank body T through the opening E and is mounted through the tubular portions15A and15B to the two studs9, which have been disposed to project from the mounting wall. The mounting operation is performed in a swinging step where the sound-absorbing device1(the sound-absorbing parts2A and2B) is set in the first state with the sound-absorbing device bent at a certain angle through the hinge3for insertion into the tank; an inserting step where the sound-absorbing device1(the sound-absorbing parts2A and2B) is put into the tank body T through the opening E, maintaining the first state, as shown inFIG. 3(a); a re-swinging step where the sound-absorbing device1(the sound-absorbing parts2A and2B) is set from the first state to the second state to be ready for use in the tank T as shown inFIG. 3(b); and a mounting step where the sound-absorbing device1(the sound-absorbing parts2A and2B) is mounted to the studs9in the tank body T as shown inFIG. 3(c).

In the swinging step, the sound-absorbing device is set in the first state, without being retained by the retainer4, by swinging the sound-absorbing part2B with respect to the sound-absorbing part2A by a certain angle about the hinge3for example. It is preferred to set the sound-absorbing device1to the first state in order to put the sound-absorbing device into the tank T through the opening E. In the shown embodiment, the sound-absorbing device is swung so as to be bent at an angle of about 45 degrees in the swinging step. In the inserting step, the sound-absorbing part2B is first put into the tank body T so as to be close to the studs9with the sound-absorbing part2A being held by a hand for example, and the sound-absorbing part2A is subsequently put into the tank T. In the re-swinging step, the sound-absorbing device is swung and switched from the first state to the second state by utilizing a reaction force caused when is the sound-absorbing part2B has an end portion brought into contact with the inner wall of the tank T. In the shown embodiment, the sound-absorbing device1is ready for use in the second state where the sound-absorbing part2A and the sound-absorbing part2B are in alignment with each other. In accordance with the arrangement of the embodiment, at the same time that the sound-absorbing device is switched to the second state, the sound-absorbing part2A and the sound-absorbing part2B are held in the second state through the above-mentioned retainer4(wherein the pawl41of the first engageable portion40is engaged with the recess46of the first retaining portion45, and the pawl43of the second engageable portion42is engaged with the pawl48of the second retaining portion47). The subsequent mounting step is conducted so as to be continuous to the re-swinging step. The sound-absorbing part2A is positioned so as to have the tubular portions15A and15B set in alignment with the corresponding studs9, being guided by the ribs16eand by the guiding recessed portions16A and16B. Then, when the sound-absorbing device1(the sound-absorbing parts2A and2B) is pressed toward the mounting wall, the respective studs9pass through the gaps defined by the opposed engageable strips19of the tubular portions15A and15B, spreading the engageable strips, and each pair of the engageable strips19is engaged with the neck between adjacent engageable blades9ccorresponding thereto, with the upright wall17being brought into contact with the mounting wall. By this engagement, the sound-absorbing device is firmly mounted to the respective studs9.

In accordance with this embodiment, the sound-absorbing device can be selectively set in the most preferred state for being put into a fuel tank and in a state for obtaining the optimum sound-absorbing property by swinging the plural sound-absorbing parts2A and2B through the hinge3as described above, the plural sound-absorbing parts extending along the length Y of the sound-absorbing device. In accordance with this sound-absorbing device, it is possible to set the sound-absorbing device in the first state and put the sound-absorbing device into a fuel tank through the opening E, followed by returning the sound-absorbing device to the second state for example. Even if the fuel tank is of a thin type, the sound-absorbing device can be provided with an excellent sound-absorbing property without preparing plural sound-absorbing devices by increasing the length of the sound-absorbing device in comparison with the conventional ones. In terms of mounting to a tank, it is possible to maintain effective insertion into the fuel tank, to make the mounting operation simple and to obtain an excellent sound-absorbing property in a mounting state (in use) even if the length of the sound-absorbing device1is increased in comparison with the conventional ones.

Second Embodiment

Each of the sound-absorbing devices1A shown inFIG. 9toFIG. 16is put into a tank through an opening (not shown) for attachment of a unit gauge formed in a tank body T forming the tank and is fitted to studs9disposed to project inside of the tank as in the first embodiment. The sound-absorbing device has a three-dimensional structure, which has a narrower width X than the width of the opening of the tank body and a greater length Y than the width of the opening of the tank body as shown inFIG. 11, wherein the sound-absorbing device is formed of sound-absorbing parts5and6coupled together in a longitudinal direction extending along the length Y through a retainer8, which also serves as a hinge. In other words, each of the sound-absorbing devices1A is formed in a three-dimensional structure having a greater length Y than the width of the opening of the tank body and is formed of sound-absorbing parts5and6, which are coupled together at an intermediate position of the sound-absorbing device in a longitudinal direction along the length so as to be swingable between a first state and a second state by the hinge function of the retainer8and are configured to selectively maintain the first state and the second state so that the sound-absorbing parts are prevent from swinging by the retaining function of the retainer8. The tank body T has studs9at totally four locations, i.e. two studs in each side, for mounting two sound-absorbing devices1A to a mounting wall of the tank body as shown in the upper schematic view inFIG. 9. Each of the studs9has a head9a, a shaft9band plural elastic engageable blades9cintegrally formed therewith as in the first embodiment.

In this embodiment, the sound-absorbing part5is a main part and is formed of plural plates50and51stacked integrally by couplers7A. The sound-absorbing part6is a sub-part and is formed of plural plates60to63stacked integrally by a coupler7B. The plates and the couplers are formed of a resin-molded article made of, e.g. a POM resin. Each of the plates50and51and the plates60to63is formed of a rigid plate, which is difficult to deform and is formed in a substantially rectangular shape. The inner plate (the first plate)50or60that is disposed at a position closest to the mounting wall of the tank body has a significantly different shape from the other plates51and61to63. The plates61to63will be explained with the plate61being taken as an example since they are identical or similar to each other in terms of shape.

In the sound-absorbing part5, the inner plate50has plural through holes53, plural projections54, left and right tubular portions55and55, guiding ribs57a, upright walls57bas stoppers, a vertical wall58, and a pair of support members50aand50aintegrally formed therewith, the through holes passing therethrough from a top side to a bottom side thereof, the projections and the tubular portions projecting from the bottom side thereof, the guiding ribs and the upright walls projecting from the top side thereof, the vertical wall projecting downward from a rear edge thereof, and the support members projecting from both lateral sides thereof as shown inFIG. 9toFIG. 11.

The through holes53are formed as small circular holes at substantially equal distances in a left-to-right direction and a front-to-rear direction of the inner plate. The projections54are formed at substantially equal distances in the left-to-right direction and the front-to-rear direction of the inner plate so that a single through hole53is surrounded by four projections54at portions except for the provision of the tubular portions55. Although each of the projections54is formed in a hollow conical shape in the shown embodiment, it is sufficient that each of the projections is formed in a tapered shape so as to be gradually narrower toward the leading edge. Each of the tubular portions55is formed as a substantially rectangular frame in transverse section. Each of the tubular portions55has engageable holes55aand a pair of regulation ribs56formed at a base side thereof, the engageable holes being oppositely formed so as to pass through front and rear rectangular walls, and the regulation ribs projecting from outer sides of left and right rectangular walls as shown inFIG. 9andFIGS. 14(a) and (b). In the right tubular portion55in the shown embodiment, the left and right rectangular walls have registration ribs59oppositely disposed on inner sides so as to extend vertically. Each of the engageable holes55ais formed in a substantially rectangular shape and is configured to engageably receive elastic pawls72of a coupler7A, which is described later in detail. Each of the registration ribs56serves as a projection for keeping a gap between each of the registration ribs and the plate51disposed below each of the registration ribs. Each of the registration ribs59serves as a rib for guiding the corresponding coupler7A. In the left tubular portion in the shown embodiment, the registration ribs are not shown for simplification. The guiding ribs57aare disposed on a rear side so as to correspond to the inlets of the tubular portions55as shown inFIG. 11. When the sound-absorbing part5is mounted to the tank body, the guiding ribs are brought into contact with studs9, making it easier to put the studs in alignment with the inlets of the tubular portions55. The upright walls57bserve as ribs for positioning the sound-absorbing part so as to keep a gap between the sound-absorbing part and the mounting wall of the tank body. When the sound-absorbing part5is mounted, the vertical wall58is brought into contact with a portion of the mounting wall of the tank body corresponding thereto, serving to stably hold the sound-absorbing part without wobble even if an impact is applied.

The plate51is formed in a rectangular shape having substantially the same size as the inner plate50and has plural through holes51aand51b, frames51c, registration ribs51dand coupling strips52integrally formed therewith, the through holes passing therethrough from a top side to a bottom side thereof, the frames disposed at right and left positions to receive the tubular portions55, the registration ribs fringing upper and lower sides of the frames51c, and each of the coupling strips being raised on both lateral sides of the plate so as to be acceptable between each pair of the support members50a(each gap84describe later) as shown inFIG. 9andFIG. 12. The through holes51aare formed as such circular holes as to receive the projections54with play and confront with the corresponding projections54when the plate51and the inner plate50are stacked each other. The through holes51bare formed in the same way as the through hole53and confront with the through holes53when the plate51and the inner plate50are stacked each other. The frames51care formed as such rectangular holes as to correspond to the tubular portions55and are fringed with the registration ribs51dprojecting from the upper and lower sides of the plate51. The registration ribs51dserve to secure a certain gap between the plate50and the plate51when the tubular portions55are inserted into the corresponding frames51cin order to stack the plate51and the inner plate50. Each of the coupling strips52on both lateral sides has a pawl52aformed on an outer side of a leading edge thereof to project therefrom.

Each of the couplers7A is formed in a substantially angular tubular shape and has an inserted portion70a, a grasping portion70b, a rectangular flange71, the elastic pawls72and engageable strips73formed therewith, the inserted portion being configured to be received into a corresponding tubular portion55, the grasping portion being continuous with the inserted portion and configured to be positioned outside the corresponding tubular portion55, the rectangular flange projecting from the outer periphery of each of the couplers to divide each of the couplers into the inserted portion70aand the grasping portion70b, the elastic pawls being disposed on respective opposing walls defining the inserted portion70a, and the engageable strips projecting from the inner sides of respective opposing walls of the inserted portion70awithout the pawls72formed therein as shown inFIGS. 16(a) to (d).

Each of the inserted portions70ais formed in such a size as to be inserted into a corresponding tubular portion55without keeping a gap between opposing walls thereof with the pawls72and the tubular portion. Each is of the inserted portions is configured to be inserted into the corresponding tubular portion along the ribs without keeping a gap between opposite walls thereof with the engageable strip73and the ribs59in a case with the ribs disposed or to be inserted into the tubular portions with keeping a slight gap between the opposite walls with the engageable strip and the corresponding tubular portion in a case without the ribs disposed as shown inFIG. 9andFIGS. 14(a) and (b). By the provision of such gaps, it is possible to make the couplers7A slightly shiftable in order to adjust the position of the couplers7A with keeping the engagement between the pawls72and the engageable holes55aeven if the position of a stud9or the distance between the relevant studs9is slightly deviated from a designed position. Each of the grasping portions70bserves as a portion to be utilized for grasping the coupler7A by a hand or a robot hand and has the engageable strips73projecting from the inner sides of the opposing walls. Each of the flanges71is configured to be brought into contact with the end face of the corresponding tubular portion55with the inserted portion70ainserted into the tubular portion55and with the elastic pawls72engaged with the engageable holes55a, and to serve as a retainer to prevent the falling out of the plate51stacked through the tubular portions. Each of the elastic pawls72is delimited by a slit having a substantially U-character shape and formed in a lower portion of the inserted portion70a. The elastic pawls are inwardly deformed in the course of being inserted into the corresponding tubular portion. When the pawls arrive at the corresponding engageable holes55a, the pawls are returned to their original states, being engaged with the engageable holes55a. It should be noted that the plates50and51have bosses50band51gformed at plural positions on the opposing sides thereof to stack the plate50and the plate51with keeping a gap therebetween corresponding to the lengths of the bosses50band51gas shown inFIG. 14.

On the other hand, the sound-absorbing part6is positioned in an obliquely downward direction with the sound-absorbing part5being horizontally positioned as shown inFIG. 10andFIGS. 15(a) and (b). This sound-absorbing part includes the inner plate60, which has plural through holes64, plural projections65, a central tubular portion66and ribs67formed therewith, the through holes passing therethrough from a front side to a rear side thereof, and the projections and the central tubular portion projecting from the rear side thereof. The through holes64are formed as small circular holes at substantially equal distances in a left-to-right direction and a vertical direction of the inner plate. The projections65are formed at substantially equal distances in the left-to-right direction and the vertical direction of the inner plate so that a single through hole64is surrounded by four projections65at portions except for the provision of the tubular portion66. Although each of the projections65is formed in a hollow conical shape in the shown embodiment, it is sufficient that each of the projections is formed in a tapered shape so as to be gradually narrower toward the leading edge. The tubular portion66is formed as a substantially rectangular frame having a hole passing through this sound-absorbing part from a front side to a rear side thereof. The tubular portion has engageable holes66aand a pair of regulation ribs66bformed at a base side thereof, the engageable holes being oppositely formed so as to pass through right and left rectangular walls, and the regulation ribs projecting from outer sides of vertical rectangular walls. Each of the engageable holes66ais configured to engageably receive elastic pawls77of the coupler7B, which is described later in detail. The ribs67are disposed at plural positions to serve as a projection for keeping a gap between each of the ribs and the subsequent plate61.

The plate61is formed in a rectangular shape having substantially the same size as the inner plate60and includes plural through holes61aand61b, a central frame61cand a registration rib61d, the through holes passing therethrough from a front side to a rear side thereof, the frame disposed to receive the tubular portion66, and the registration rib fringing the frame61c(the explanation of which is also applied to plates62and63). The through holes61aare disposed to correspond to the through holes64. The through holes61bare formed as such circular holes as to receive the projections65with play. When the plate61and the inner plate60are stacked, the projections are put in and face the through holes61bat corresponding positions with play. The frame61cis formed as such a rectangular hole as to correspond to the tubular portion66and is fringed with the registration rib61d. The registration rib61dserves to secure a certain gap between the plate61and the inner plate60when the tubular portion66is inserted into the corresponding frame61cin order to stack the plate61and the inner plate60.

The coupler7B is formed in a substantially angular tubular shape and has an inserted portion75, a rectangular flange76and the elastic pawls77formed therewith, the inserted portion being configured to be received into the tubular portion66, the rectangular flange projecting from the outer periphery of the inserted portion at a rear side of the coupler, and the elastic pawls being disposed on respective opposing walls defining the inserted portion75. The inserted portion75is formed in such a size that the inserted portion can be inserted into the tubular portion66without keeping a gap between opposing walls thereof with the pawls77and the tubular portion66. The flange76is configured to be brought into contact with the end face of the tubular portion66with the inserted portion75inserted into the tubular portion66and with the elastic pawls77engaged with the engageable holes66a, and to serve as a retainer to prevent the falling out of the plates61,62and63stacked through the tubular portion. Each of the elastic pawls77is formed so as to be delimited by a slit having a substantially U-character shape and formed in a lower portion of the inserted portion75. The elastic pawls are inwardly deformed in the course of being inserted into the tubular portion66. When the pawls arrive at the engageable holes66a, the pawls are returned to their original states, being engaged with the engageable holes66a.

The retainer8is formed of a retaining portion80disposed on the inner plate50forming the sound-absorbing part5and an engageable portion85disposed on the inner plate60forming the sound-absorbing part6as shown inFIG. 9andFIGS. 13(a) to (c), having both of a holding function and a hinge function. In the shown embodiment, the retaining portion80is disposed on each ends of the inner plate50, and the engageable portion85is disposed on each end of the inner plate60. Accordingly, the sound-absorbing device according to this embodiment may be used in a connecting state other than the connecting state shown in the drawings. For example, the sound-absorbing device may be configured so that two sound-absorbing parts6are coupled to the right and left ends of the sound-absorbing part5, or two sound-absorbing parts5are coupled to both ends of the sound-absorbing part6.

Each of the retaining portion80is disposed to connect between the support member50aand the support member50aand is formed of a vertical plate81extending vertically, an inner transverse rib82formed on an inner side of the vertical plate81and projecting from the vertical plate at a substantially middle position in a vertical direction, and an outer transverse rib83formed at a lower position on an outer side of the vertical plate81so as to project therefrom. The vertical plate81is disposed to keep a gap having a certain width between the vertical plate and an edge portion of the plate50corresponding thereto. On the other hand, the engageable portion85is formed of a short engageable strip86and a long engageable strip87, which are disposed at a substantially middle position on a lateral side of the inner plate60, the short engageable strip projecting from the lateral side so as to extend downward from above, and the longer engageable strip projecting from the lateral side so as to extend upward from below, with the result that both engageable strips form an engageable space88in a semi-closed state.

By the above-mentioned arrangement, the inner plate60(the sound-absorbing part6) is hinged to the inner plate50(the sound-absorbing part5) so as to be prevented from being swung as required as described below. In this hinged coupling, the engageable portion85is coupled to the retaining portion80so that the short engageable strip86is engaged with the outer transverse rib83, and the long engageable strip87is passed through a lower portion of the gap84and is engaged with a lower inner end of the vertical plate81as shown inFIG. 13(b) as a reference view. In this state, the inner plate60(the sound-absorbing part6) can be clockwise swing in an obliquely downward direction, i.e. until the long engageable strip87is brought into contact with the inner transverse rib82as shown inFIG. 13(c) (In the shown embodiment, the inner plate60is coupled to the inner plate50so as to be swingable by an angle of about 30 degrees).

In order to set the sound-absorbing device in a retaining state, the inner plate60is forcibly swung in a further clockwise direction from the state shown inFIG. 13(c). Thus, as shown inFIG. 9, the short engageable strip86of the inner plate60(the sound-device6) is engaged with the outer transverse rib83, and the long engageable strip87of the inner plate60(the sound-absorbing device6) forcibly climbs over the inner transverse rib82to be engaged with a top end face of the inner transverse rib82, with result that the inner plate60(the sound-absorbing device6) is retained so as not to be swingable with respect to the inner plate50(the sound-absorbing device5). When the retainer8is switched to the above-mentioned retaining state, the retainer is prevented from being inadvertently released from the retaining state since the long engageable strip87fills in the gap84while the long engageable strip87has a leading edge caught between the top end face of the inner transverse rib82and the pawl52aof the coupling strip described above.

As in the first embodiment, the above-mentioned sound-absorbing device1A is put into the tank body T through the opening of the tank and is mounted through the tubular portions7A and7A to the two studs9, which have been disposed to the mounting wall. The mounting operation is performed in a swinging step where the sound-absorbing device1A (the sound-absorbing parts5and6) is set in the first state by the hinge function of the retainer8for insertion into the tank; an inserting step where the sound-absorbing device1A (the sound-absorbing parts5and6) is put into the tank body T through the opening of the tank, maintaining the first state; a re-swinging step where the sound-absorbing device1A (the sound-absorbing parts5and6) is set from the first state to the second state to be ready for use in the tank T; and a mounting step where the sound-absorbing device1A (the sound-absorbing parts5and6) is mounted to the studs9in the tank body T as shown inFIG. 9.

In the swinging step, the sound-absorbing device is set in the first state, without being retained by the retainer8, by utilizing the hinge function of the retainer8to swing the sound-absorbing part6with respect to the sound-absorbing part5by a certain angle for example. It is preferred to set the sound-absorbing device1A to the first state in order to put the sound-absorbing device into the tank T. In the inserting step, the sound-absorbing part6is first put into the tank body T so as to be close to the studs9with the sound-absorbing part5being held by a hand for example, and the sound-absorbing part5is subsequently put into the tank T. In the re-swinging step, the sound-absorbing device is swung and switched from the first state to the second state by utilizing a reaction force caused when the sound-absorbing part6has an end portion brought into contact with the inner wall of the tank T. In the shown embodiment, the sound-absorbing device1A is ready for use in the second state where the sound-absorbing part6is set at an angle of about 45 degrees with respect to the sound-absorbing part5. In accordance with the arrangement of this embodiment, at the same time that the sound-absorbing device is switched to the second state, the sound-absorbing part5and the sound-absorbing is part6are held in the second state through the retaining function of the retainer8described above. The subsequent mounting step is conducted so as to be continuous to the re-swinging step. Specifically, the sound-absorbing part5is positioned so as to have the respective tubular portions7A set in alignment with the corresponding studs9, being guided by the ribs57a. Then, when the sound-absorbing device1A (the sound-absorbing parts5and6) is pressed toward the mounting wall, the respective studs9pass through the gaps defined by the opposed engageable strips73of the corresponding tubular portions7A, spreading the engageable strips, and each pair of the engageable strips73is engaged with the neck between adjacent engageable blades9ccorresponding thereto with the upright walls57bbeing brought into contact with the mounting wall. By this engagement, the sound-absorbing device is firmly mounted to the respective studs9. Accordingly, the above-mentioned sound-absorbing device1A can also have an advantage similar to the first embodiment, and the structures of the respective parts can be simplified since the retainer8has both of the hinge function and the retaining function.

Although the respective embodiments have been described about a case where the tank body T is formed by blow molding, the tank body may be formed by any other method than blow molding as long as the tank includes the opening. Although the respective embodiments have been described about a case where each of the projections is formed in such a substantially conical shape having a hollow space therein, each of the projections may have a leading edge cut or have a peripheral wall curved. In such cases, when the leading edge has a through hole or a small aperture formed therein, it is possible to prevent a liquid, such as fuel, from staying inside the hollow space even if the projection is put with the leading facing downward.

The entire disclosure of Japanese Patent Application No. 2006-052810, filed on Feb. 28, 2006, including the specification, claims, drawings and summary, is incorporated herein by reference.