US20070192955A1

US20070192955A1 - Shelter bed

Info

Publication number: US20070192955A1
Application number: US11/704,975
Authority: US
Inventors: Miyoji Matoba
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-02-22
Filing date: 2007-02-12
Publication date: 2007-08-23
Also published as: JP2007222320A

Abstract

A shelter bed comprising: a mattress on which at least one user can lie down; a frame on which the mattress is set, and which comprises legs supporting the entire shelter bed on a floor and a buoyancy device generating buoyancy holding the entire shelter bed on a water surface; and a protective shell for protecting the user, the protective shell being movable between a first position in which the protective shell covers the user lying on the mattress and a second position in which access to the mattress is released to the user.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a shelter bed, and in particular, to a shelter bed for protecting a user's body from falling objects in an event of disasters, and for allowing a user to urgently evacuate in an event of water-related disasters such as house flooding.

DESCRIPTION OF RELATED ART

Japanese Patent Application Laid-open Publication No. 8-294430 discloses an earthquake disaster shelter bed allowing a person to shelter oneself inside a bed frame thereof having loading capacity of 2 tons. A drawing container is provided in the shelter for containing emergency survival supplies such as water, foods and a flashlight.
Japanese Patent Application Laid-open Publication No. 2002-85197 discloses a bed for rescue and first-aid. The bed includes a mattress formed of a resin foam material and a roof wall member to be attached to the mattress. The roof wall member is normally folded, and, when unfolded, forms a shape surrounding the mattress, which has a pair of roof top portions and a pair of substantially triangular gable side portions respectively supporting both ends of the roof top portions. The mattress provides buoyancy large enough to float at least one user on a water surface. When houses are flooded in an event of water-related disasters, the mattress allows a sick or physically disabled individual to float on the water surface. In a prolonged life as evacuees, user's privacy can be secured by attaching the roof wall member to the mattress.

SUMMARY OF THE INVENTION

As for the former of the above-described beds, a user has to move to a shelter provided inside the bed frame so as to protect his/her body from falling objects such as rubble of houses in an event of earthquakes and the like. This movement is difficult for persons incapable of immediately moving their bodies, such as a physically disabled and sick individual.
As for the latter of the above-described beds, there is a problem that a user cannot protect his/her body from rubble falling onto the bed in the event of disasters such as earthquakes. Moreover, since the mattress has a flat shape, the mattress is unstable when floating on the water surface and causes large drag when moving on the water surface, which makes it difficult for a rescue worker to tow the mattress with a physically disabled or sick individual thereon while keeping his/her body on a water surface in the event of water-related disasters.
The present invention was made in the light of these problems. An object of the present invention is to provide a shelter bed which quickly protects the user lying on the shelter bed from falling objects in an event of earthquakes and the like, and achieves sufficient and stable buoyancy to have the user floated on a water surface and to make rescue work easier in the event of water-related disasters.
An aspect of the present invention is a shelter bed comprising: a mattress on which at least one user can lie down; a frame on which the mattress is set, and which comprises legs supporting the entire shelter bed on a floor and a buoyancy device generating buoyancy holding the entire shelter bed on a water surface; and a protective shell for protecting the user, the protective shell being movable between a first position in which the protective shell covers the user lying on the mattress and a second position in which access to the mattress is released to the user.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanying drawings wherein:

FIG. 1A is a perspective view showing a shelter bed according to a first embodiment of the present invention, the shelter bed having a protective shell being housed therein;

FIG. 1B is a perspective view of the shelter bed of FIG. 1A, which shows a state where the protective shell is moved to cover a person lying on the shelter bed;

FIG. 2 is a front view of the shelter bed of FIG. 1A in which a leg on the left side of the bed is omitted;

FIG. 3 is a cross-sectional view of the shelter bed of FIG. 1A, which is taken along the line III-III of FIG. 2;

FIG. 4 is a cross-sectional view of the shelter bed of FIG. 1A, which is taken along the line IV-IV line of FIG. 2;

FIG. 5 is a perspective view showing a shelter bed according to a second embodiment of the present invention;

FIG. 6 is a side view of the shelter bed of FIG. 5, which is viewed from the head side;

FIG. 7 is a perspective view showing a shelter bed according to a third embodiment of the present invention;

FIG. 8 is a side view of the shelter bed of FIG. 7, which is viewed from the head side, and in which a headboard is omitted;

FIG. 9 is a perspective view showing a shelter bed according to a fourth embodiment of the present invention; and

FIG. 10 is a perspective view of the shelter bed of FIG. 9, which shows a state where the protective shell is moved to cover a person lying on the shelter bed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be explained below with reference to the drawings, wherein like members are designated by like reference characters.
As shown in FIGS. 1 to 4, a shelter bed 1 according to a first embodiment of the present invention is provided with a rectangular mattress 5 having such a size that at least one user can lie down on the mattress 5, and a bed frame 3 onto which the mattress 5 is set.
The bed frame 3 includes a pair of legs 7 which supports the entire shelter bed 1 on the floor, and which extend in the longitudinal direction of the shelter bed 1 (from the head side to the hoot side) along right and left side edges of the shelter bed 1 (both ends in the width direction of the bed), and a buoyancy device 9 which is provided between the two legs 7 below the mattress 5, and which generates buoyancy to hold the entire shelter bed 1 (including the user laying on the mattress 5) on a water surface.
The leg 7 has a substantially rectangular shape in a plan view and in cross-section perpendicular to the longitudinal direction of the bed. The buoyancy device 9 as a whole has a ship shape, and has a shape of a ship's bottom showing a substantially V-shape in the cross-section perpendicular to the longitudinal direction of the bed. That is, in the cross-section perpendicular to the longitudinal direction of the bed, the legs 7 and the buoyancy device 9 together form a substantially M shape.
Lower end portions 7 a of the respective legs 7 are submerged in water when the shelter bed 1 floats on the water surface. As will be described later, protective shell housing portions 15 are provided inside the respective legs 7. Thus, the legs also form a part of the buoyancy device 9 to generate buoyancy when the shelter bed 1 floats on the water surface. The buoyancy generated by these legs 7 generates a moment to suppress the rolling movement around the axis of the longitudinal direction of the shelter bed 1, so that the shelter bed becomes stable on the water surface.
The buoyancy device 9 is formed of, for example, a resin foam material such as styrofoam, an air bag (a buoyancy bag), or the like.
The bed frame 3 is provided with a protective shell 11 for protecting a user. The protective shell 11 is provided above the mattress 5 in a way that the protective shell 11 is movable between a closed position (a first position) in which the protective shell 11 covers a user lying on the mattress 5 and an open position (a second position) in which access to the mattress 5 is released to the user.
In the first embodiment, the protective shell 11 is formed of a pair of flat plate members 13 forming a gable roof in the closed position. These flat plate members 13 are formed of, for example, a resin plate material such as a reinforced plastic or a metal plate material such as stainless material.
The protective shell housing portions 15 for housing the respective flat plate members 13 are provided inside the respective legs 7. In the upper portions of the respective protective shell housing portions 15, opening portions 17 into which the respective flat plate portions 13 are inserted are formed. The opening portions 17 extend in the longitudinal direction of the shelter bed 1 along right and left end edges of the shelter bed 1.
A flat headboard 19 and a flat footboard 21 are respectively provided to the head and foot sides of the shelter bed 1. Mountain-shaped guide grooves 23 are respectively provided to the sides of the headboard 19 and the footboard 21, the sides facing each other. Each of the guide grooves 23 guides a corresponding one of the flat plate members 13 which moves between the open position in which the flat plate member 13 is housed inside the corresponding protective shell housing portion 15 and the closed position in which the gable roof is formed above the mattress 5. Moreover, the flat plate members 13 support loads applied from above onto each flat plate member 13 in the closed position.
The headboard 19 and the footboard 21 each have space (not shown) inside their thicknesses. As shown by the chain double dashed line on the left side in FIG. 4, a protective shell driving device 25, which drives the corresponding flat plate member 13, is provided inside each space. The protective shell driving device 25 is formed of, for example, a plurality of sprockets 27 fixed to the headboard 19 or to the footboard 21; chains 29 intermeshing with the sprockets 27 in an endless annular form; and a rotation driving unit 28 such as a motor which causes the chains 29 to rotate in forward and reverse direction. The plurality of sprockets 27 at least includes a sprocket 27 a provided near an apex formed by the mountain-shaped guide grooves 23, a sprocket 27 b provided to a vicinity of one of the opening portions 17 of the respective protective shell housing portions 15, and a sprocket 27 c positioned above a line connecting the sprockets 27 a and 27 b to each other. In the first embodiment, a total of four protective shell driving devices 25 are respectively provided to right and left sides of the headboard 19 and the footboard 21.
To upper end portions 13 a of the side edges on the head and foot sides of the respective flat plate members 13, a connecting member 13 b is attached with an unillustrated connecting shaft. Each flat plate member 13 b is connected to the corresponding chain 29 of each protective shell driving device 25. Thus, the upper end portions 13 a of the side edges on the head and foot sides of the respective flat plate members 13 move among the sprockets 27 along with the rotation of the chains 29. On the other hand, each of lower end portions 13 c of side edges on the head and foot sides of the corresponding flat plate member 13 moves while being guided by the guide groove 23.
For example, when the chains 29 is rotated forward (clockwise rotation in FIG. 4) by the rotation driving unit 28, each flat plate member 13 housed inside the corresponding protective shell housing portion 15 is once pulled out upward, and then moves toward the apex formed of the guide grooves 23 to stop at a stop position on the upper end of the corresponding guide groove 23. This operation is shown by the chain double dashed line in FIG. 4. At the stop position, the upperend edges of the respective flat plate members 13 are in contact with each other over the entire length thereof. Thereby, each flat plate member 13 forms a gable roof above the mattress 5 to cover the user lying on the mattress 5 as shown by the chain double dashed line hatching in FIGS. 1B and 4.
When the chains 29 are reversely rotated (anticlockwise rotation in FIG. 4) by the rotation driving portion 28, each flat plate member 13 performs an operation opposite to that in the case of the forward rotation, and moves by being guided by the guide grooves 23. Thereby, the flat plate members 13 are respectively stored in the protective shell housing portions 15.
It is to be noted that the protective shell driving device 25 shown by the chain double dashed line on the left side in FIG. 4 represents the above-described four protective shell driving devices 25 to which other protective shell driving devices have a similar configuration. The above-described protective shell driving devices 25 shows one example. The configuration thereof is not limited to this and may be another configuration. For example, it is possible to employ a configuration in which the upper end portions 13 a respectively of the side edges on the head and foot sides of the flat plate members 13 are connected to rods of motor cylinders or fluid cylinders of which crevices are fixed to the headboard 19 or to the footboard 21.
In addition, the upper end edges respectively of the flat plate members 13 may be configured to be engageable with each other in the closed position. For example, a plurality of hooks are provided along the total length of the upper end portion of the flat plate member 13 on the left side of the shelter bed 1 and a plurality of engaging holes to engage with the hooks are provided respectively in positions corresponding to the plurality of hooks in the upper end portion of the flat plate member 13 on the right side of the shelter bed 1. In this case, rotation speed or the like of the rotation driving unit 28 of the corresponding protective shell driving device 25 is adjusted so that the flat plate member 13 on the right side of the shelter bed 1 would stop at a stop position before the flat plate member 13 on the left side stops.
The bed frame 3 includes, for example, a vibration detecting unit 30 a for detecting vibrations or the like caused by P-waves of earthquakes and a control device 30 b for controlling rotations of the rotation driving unit 28 of the corresponding protective shell driving device 25 on the bases of detected values obtained by the vibration detecting unit 30 a. The vibration detecting unit 30 a transmits data on detected vibrations or detected signals to the control device 30 b in the event where P-wave vibrations or vibrations greater than vibrations set in advance on a seismic intensity scale occur. The control device 30 b transmits the control signals to the rotation driving unit 28 of the corresponding protective shell driving device 25 on the bases of the received data or the detected signals. The rotation driving unit 28 rotates forward on the bases of the received control signals, and causes both of the flat plate members 13 to move to the closed position. Thus, the system is constituted in which the protective shell 11 is automatically operated to protect a user lying on the mattress 5 when the earthquake occurs. Incidentally, the vibration detecting device 30 a and the control device 30 b may be those which receive warnings from a wide-area seismic warning system, and which use the received signals for the above-described control. In addition, the devices may be those provided with functions to generate a SOS signal of which originating position can be identified, and to communicate in case of emergency.
A propulsive device is provided in the rear portion of a buoyancy device 9 (on the foot side of the shelter bed). The propulsive device propels the shelter bed 1 when the shelter bed 1 floats on the water surface with buoyancy generated by the buoyancy device 9. The propulsive device includes a screw 33 projected rearward from the rear surface of the buoyancy device 9; a rudder 35 which is placed in the rear of the screw 33, and which changes a direction of propulsion by changing a direction of slip stream of the screw 33; a motor M of which driving shaft is directly connected to the screw 33; and a storage battery 32 for supplying driving power to the motor M. The motor M and the storage battery 32 are built in a screw driving chamber 31 provided behind the buoyancy device 9. Incidentally, the number of revolutions of the motor M is controlled by another control device. An operation control panel 31 a is provided in one section on the headboard 19 of the bed frame 3. The operation control panel 31 a includes an operation switch and the like for operating the revolution speed of the screw 33 or of the motor M and the direction of the rudder 35. Using this control panel 31 a, the user of the shelter bed 1 can operate the revolution speed of the screw 33 and the direction of the rudder 35 while lying on the mattress 5.
Operations of the shelter bed 1 of the first embodiment will be described below.
As shown in FIG. 1A, the pair of flat plate members 13 are normally housed inside the respective protective shell housing portions 15 provided in the legs 7 on the right and left sides of the bed. That is, the protective shell 11 is in the open position, the user can freely access the mattress 5, and the shelter bed 1 is used as a normal bed.
In the event where p-wave vibrations or vibrations greater than vibrations set in advance on a seismic intensity scale occur, the vibration detecting device 30 a automatically transmits detection data to the control device 30 b so that the control unit 30 b controls the rotation driving unit 28 of the corresponding protective shell driving device 25 to cause the rotation driving unit 28 to rotate forward. After that, the two flat plate members 13 move to the closed position to form the gable roof above the mattress 5. As a result, even persons unable to get up from the bed by themselves, such as the physically disabled or the sick individuals, can immediately protect their bodies from falling objects such as rubble of houses and the like in the event of earthquakes. Here, as described above, if the top edges of the flat plate members 13 are engaged with each other in the closed position, the two flat plate members 13 integrally form an angle section. Hence, the flat plate members 13 support significant weight applied from thereabove.
Furthermore, in the event of water-related disasters such as flood which floods houses, the shelter bed 1 immediately changes itself to a boat. That is, the shelter bed 1 can float on the water surface together with the user on the mattress 5 by receiving the buoyancy generated by the buoyancy device 9. This shelter bed 1 as a boat has such a bottom surface that the legs 7 on the respective right and left sides of the bed, and the buoyancy device 9 show a substantially M-shape in the cross-section perpendicular to the longitudinal direction of the bed. Thereby, the shelter bed 1 is stable with suppressed rolling of the boat floating on the water surface. The propulsion device provided with the screw 33 capable of adjusting the number of revolutions and the rudder 35 capable of steering the bed is provided behind the buoyancy device 9. The user of the shelter bed 1 operates the operation control panel 31 a while lying thereon, so that the user can easily escape to a safer place.
Next, a shelter bed 37 of a second embodiment of the present invention will be described. It is to be noted that only configurations different from those of the above-described shelter bed 1 according to the first embodiment will be described in detail. Components which are the same as those of the shelter bed 1 of the first embodiment will be denoted by the same reference numerals, and the detailed description of their configurations and operations will be omitted.
As shown in FIGS. 5 and 6, a shelter bed 37 has a semi-cylindrical protective shell 39. The protective shell 39 is attached to a side edge of a bed frame 3 in a way that the protective shell 39 can be opened and closed. The protective shell 39 is attached, for example, to an upper portion of a leg 7 on the left side of the bed with a hinge portion 41 on one side of side edges in the width direction of the bed, for example, the side edge on the left side of the bed. The protective shell 39 is formed of a resin plate material such as a transparent or semi-transparent reinforced plastic.
Incidentally, this protective shell 39 may be configured to be opened and closed manually. However, the protective shell 39 may be configured to be opened and closed automatically with a following driving mechanism being provided. For example, a part of the protective shell 39 which rotationally moves around the hinge portion 41 may be connected to a motor cylinder and to a fluid cylinder of which crevice is fixed to the bed frame 3. By driving the cylinders, the protective shell 39 may be automatically driven to be rotated. The protective shell 39 may be configured in a way that a gear mechanism is directly connected to a rotating member of the hinge portion 41, and that the gear mechanism is rotationally driven by the motor or the like. Hence, the protective shell 39 is automatically driven to be rotated.
The description of an operating timing or the like of these driving mechanisms is similar to that of the protective shell 11 of the first embodiment. Accordingly, the description is omitted. The directions of opening or closing the protective shell 39 are not limited to those in the present embodiment. For example, the left side of the bed, the foot side, or the head side may be opened by respectively providing a hinge portion on the right side of the bed, the head side, or the foot side.
Next, a shelter bed 43 according to a third embodiment of the present invention will be described. Configurations different from those of the above-described shelter bed 1 according to the first embodiment will be described in detail. Components which are the same as those of the shelter bed 1 of the first embodiment will be denoted by the same reference numerals, and the detailed description of their configurations and operations will be omitted.
As shown in FIGS. 7 and 8, a shelter bed 43 has a semi-cylindrical protective shell 45. As shown in FIG. 8, a pair of circular-shaped guide grooves 51 are provided respectively to sides of a headboard 19 and a footboard 21, which face each other, for guiding movement of the protective shell 45 from an open position to a closed position. An opening portion 49 is provided in a region which is located in the upper portion of one side of side edges in the bed width direction of a bed frame 3, and which is on the left of a mattress 5. The protective shell 45 is inserted into, and is passed through the opening portion 49. A protective shell housing portion 47 for housing the protective shell 45 inserted from the opening portion 49 is provided below a buoyancy device 9 of the shelter bed 43. The protective shell 45 is placed in the protective shell housing portion 47 in a way that the protective shell 45 surrounds the buoyancy device 9 from beneath the buoyancy device 9.
The semi-cylindrical protective shell 45 is fit into the guide groove 51 on the side edges on the head and foot sides in a way that the protective shell 45 can slide. The protective shell 45 is rotatable around the central axis of the semicylinder thereof. The protective shell 45 is formed of a resin plate material such as a transparent or semi-transparent reinforced plastic.
Inside the end portions on the head and foot sides of the bed frame 3 of the shelter bed 43 is provided with a protective shell driving device 50 for driving the semi-cylindrical protective shell 45. As shown in FIG. 8, the protective shell driving device 50 includes a rack 50 a provided to an outer circumferential surface of the protective shell 45 in both end portions in the longitudinal direction of the bed; a pinion 50 b intermeshing with the rack 50 a; and a rotation driving device 50 c such as a motor for rotationally driving the pinion 50 b. When the rotation driving device 50 c rotationally drives the pinion 50 b, the protective shell 45 is driven via the rack 50 a intermeshing with the pinion 50 b. Then, the protective shell 45 passes through the opening portion 49 along with the rotation around the central axis of the semi-cylinder thereof, while moving between the open position, that is, the position where the protective shell 45 is housed in the protective shell housing portion 47 and the closed position, that is, the position where the protective shell 45 is above the mattress 5 to cover the mattress 5. Note that the protective shell driving device 50 is one example. A device driving the protective shell 45 is not limited to this, and may have another configuration. In addition, the opening and closing directions of the protective shell 45 are not limited to the present embodiment, and an opening portion 49 may be provided to the right side of the bed, and the protective shell 45 may be opened from the left side of the bed.
Next, a shelter bed 53 according to a fourth embodiment of the present invention will be described. Configurations different from those of the above-described shelter bed 1 according to the first embodiment will be described in detail. Components which are the same as those of the shelter bed of the first embodiment will be denoted by the same reference numerals, and the detailed description of their configurations and operations will be omitted.
As shown in FIGS. 9 and 10, a shelter bed 53 is provided with a protective shell 55 formed of a plurality of semi-cylindrical divided shelter shells 55 a, 55 b, and 55 c, each of which is movable in the longitudinal direction of the bed.
On the upper surfaces of the side edge portions on the right and left of the bed frame 3 of the shelter bed 53, guide grooves 57 extending in the longitudinal direction of the bed are provided. The divided protective shells 55 a, 55 b, and 55 c are fit in the guide grooves 57 respectively in both end edges in the width direction of the bed in a way that the protective shells 55 a, 55 b, and 55 c can slide therein in the longitudinal direction of the bed. In addition, the divided protective shell 55 a on the head side and the divided protective shell 55 b in the middle are movable along with each other. Meanwhile, flanges or the like capable of being engaged with each another are provided to the end portion on the foot side of the divided protective shell 55 a on the head side and the end portion on the head side of the divided protective shell 55 b in the middle so that both of the protective shells are not separated from each other completely (a gap between the protective shells is not caused in a plan view). The divided protective shell 55 c on the foot side and the divided protective shell 55 b in the middle also have a similar configuration to that described above so that both of the protective shells would not be separated from each other completely. Each of the divided protective shells 55 a, 55 b, and 55 c is formed of a resin plate material such as a transparent or semi-transparent reinforced plastic.
Inside the legs 7 of the bed frame 3 of the shelter bed 53 is provided with a protective shell driving device 60 for driving the protective shells 55 a, 55 b, and 55 c. As shown in FIGS. 9 and 10, the protective shell driving device 60 includes an endless chain 60 a extending along the guide groove 57; a pair of sprockets 60 b around which the endless chain 60 is wound; a rotation driving device 60 c such as a motor which rotationally drives one of the sprockets 60 b, and a junction 60 d which connects the chain 60 a to the divided protective shell 55 a on the head side, and which is movable to the head side or to the foot side along the guide groove 57. When the rotation driving device 60 c rotationally drives the sprockets in the anticlockwise direction in FIGS. 9 and 10, the divided protective shell 55 a is driven through the chain 60 a wound therearound and the junction 60 d attached thereto to move to the head side along the guide groove 57. When the divided protective shell 55 a on the head side moves by its width in the longitudinal direction of the bed, the head side of the divided protective shell 55 a and a portion of the end portion on the head side of the divided protective shell 55 b in the middle are engaged with each other, and the divided protective shell 55 b in the middle also starts moving together with the divided protective shell 55 a on the head side. Thereafter, when the end portion on the head side of the divided protective shell 55 a on the head side is in contact with the headboard 19, all of the divided protective shells 55 a, 55 b, and 55 c cover the mattress 5 entirely without a gap. In a case where the protective shell 55 is moved from such a closed position to the open position, that is, where the protective shell 55 is moved to a position where all of the divided protective shells 55 a, 55 b, and 55 c are gathered on the foot side of the shelter bed while being stacked on one another, the reverse of the above-described operations is carried out.
The protective shell driving device 60 is one example. A device for driving each divided protective shell 55 is not limited to this, and may have another configuration. Although the number of divided protective shells is three in the above-described embodiment, it may be four or more. In addition, in the above-described embodiment, the open position is defined as a position where the divided protective shells are gathered on the foot side. However, the open position may be defined as a position where the protective shells are gathered on the head side. The shape of each divided protective shell is not limited to semi-cylindrical, and it may be a polygonal column shape.
The preferred embodiments described herein are illustrative and not restrictive, and the invention may be practiced or embodied in other ways without departing from the spirit or essential character thereof. For example, the size of the mattress is not limited to a single size, and it may be a double size, king size, queen size or the like. In addition, the timing of closing the protective shell may not only be at the time when the vibration detecting device detects vibrations, but also be any suitable timing after the user on the shelter bed falls asleep. The buoyancy device is not limited to a fixed type, and may be an air bag which is contained while being normally folded, and which automatically expands in case of emergency.
The scope of the invention being indicated by the claims, and combinations of all or any of the above-described embodiments, all variations and modifications which come within the meaning of claims are intended to be embraced herein.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 2006-045734, filed on Feb. 22, 2006, the disclosure of which is expressly incorporated herein by reference in its entirety.

Claims

1. A shelter bed comprising:

a mattress on which at least one user can lie down;

a frame on which the mattress is set, and which comprises legs supporting the entire shelter bed on a floor and a buoyancy device generating buoyancy holding the entire shelter bed on a water surface; and

a protective shell for protecting the user, the protective shell being movable between a first position in which the protective shell covers the user lying on the mattress and a second position in which access to the mattress is released to the user.

2. The shelter bed according to claim 1, wherein the legs constitute a part of the buoyancy device.

3. The shelter bed according to claim 2, wherein the legs extend in a longitudinal direction of the shelter bed along both side edges in a width direction of the shelter bed.

4. The shelter bed according to claim 3, wherein the legs house the protective shell therein.

5. The shelter bed according to claim 1, wherein the protective shell is a pair of flat plate members housed in the legs, which form a gable roof in the first position.

6. The shelter bed according to claim 1, wherein one side edge of the protective shell is hinged to the frame.

7. The shelter bed according to claim 1, wherein the protective shell has a semi-cylindrical shape, and moves between the first and second positions while rotating about the central axis of the semi-cylindrical shape thereof.

8. The shelter bed according to claim 1, wherein the protective shell includes a semi-cylindrical shell movable in the longitudinal directions of the shelter bed.

9. The shelter bed according to claim 1, wherein the buoyancy device is provided with a propulsion device for propelling the shelter bed in an event where the shelter bed floats on the water surface.