Aqualung

Abstract

To provide a compact and easy-to-use underwater breathing apparatus. [Solution] The underwater breathing apparatus comprises a first air supply mechanism 1 and a second air supply mechanism 2 that supply the air to an intake hose, and the first air supply mechanism 1 and the second air supply mechanism 2 supply air to the intake hose by repeatedly shifting between an intake position in which the air to be discharged is taken in and an exhaust position in which the air taken in is discharged. The underwater breathing apparatus comprises a first force application means D that applies a force from a user to the first air supply mechanism 1 as a force for displacing the first air supply mechanism 1 from the exhaust position to the intake position, a second force application means 8 that applies a force to the second air supply mechanism 2 to maintain it in the intake position, and a displacement force transmission means 64, 7 that transmits the force for displacing one of the first air supply mechanism 1 and the second air supply mechanism 2 from the exhaust position to the intake position to the other of the first air supply mechanism 1 and the second air supply mechanism 2 as a force for displacing the other from the intake position to the exhaust position.

Description

[Technical field]

[0001] The present invention relates to underwater breathing apparatus for breathing underwater, and more particularly to underwater breathing apparatus that does not use an oxygen tank. [Background technology]

[0002] Conventionally, devices using oxygen cylinders such as snorkels and Aqualung (registered trademark) have been known as devices for breathing underwater. However, when using a snorkel, breathing is only possible when the tip of the snorkel is above the water surface, so it is not possible to dive deep. On the other hand, devices using oxygen cylinders do not have the same restrictions as snorkels, but they are expensive and require training, so they are not easy to use.

[0003] To solve these problems, the inventor of the present invention devised the breathing apparatus for diving described in Patent Document 1. This breathing apparatus has an air inlet tube that is supported through a main body that floats on the water, and a snorkel mouthpiece is attached to the tip of the air inlet tube. This structure allows the user to dive underwater for the length of the air inlet tube.

[0004] However, when diving deep using such breathing equipment, there is a problem that breathing is not possible due to water pressure. To solve such a problem, it has been proposed to provide a pump in the breathing equipment. For example, Patent Document 2 discloses a tool that supplies air using a small air compressor attached to a float. Patent Documents 3 to 5 disclose tools equipped with a pump that is operated by the force of the user. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Utility Model Registration No. 3170906 [Patent Document 2] JP 2006-256590 A [Patent Document 3] Special Publication No. 1-503696 [Patent Document 4] Japanese Utility Model Application Publication No. 55-047471 [Patent Document 5] Japanese Patent Application Publication No. 57-501371 Summary of the Invention [Problem to be solved by the invention]

[0006] By using the techniques of Patent Documents 2 to 5, air is supplied by a pump, so the user can breathe against the water pressure. However, the technique of Patent Document 2 uses an electrically driven air compressor, so the problem remains that the equipment is expensive. In addition, the techniques of Patent Documents 3 to 5 use a pump that is actuated by the force of the user, so it is relatively inexpensive and easy to use. However, in order to supply sufficient air with one operation, it is necessary to increase the stroke of the pump or, in the case of a cylinder pump, to increase the diameter of the cylinder, which may result in an increase in the size of the equipment.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide underwater breathing apparatus that is compact and easy to use. [Means for solving the problem]

[0008] In order to solve the above problems, the underwater breathing apparatus of the present invention comprises an intake hose for supplying air to a user underwater, a housing having a longitudinal axis, and first and second air supply mechanisms contained in the housing for supplying the air to the intake hose, wherein an insertion hole for inserting the intake hose is formed in the bottom of the housing, and a weight for floating the housing on the water surface with the longitudinal axis of the housing aligned substantially vertically is provided in the bottom of the housing, and the first and second air supply mechanisms have an intake posture in which the air to be discharged is taken in and an exhaust posture in which the air taken in is discharged. the first force acting means acting on the first air supply mechanism as a force to displace the first air supply mechanism from the discharge position to the intake position, a second force acting means acting on the second air supply mechanism as a force to maintain the second air supply mechanism in the intake position, and a displacement force transmission means transmitting the force with which one of the first air supply mechanism and the second air supply mechanism is displaced from the discharge position to the intake position to the other of the first air supply mechanism and the second air supply mechanism as a force to displace the other of the first air supply mechanism and the second air supply mechanism from the intake position to the discharge position.

[0009] According to this configuration, the first air supply mechanism is displaced from the discharge position to the intake position by the user applying force to the first force application means. Meanwhile, the second air supply mechanism is displaced from the intake position to the discharge position by the force transmitted by the displacement force transmission means, which displaces the position of the first air supply mechanism. As a result, air is discharged from the second air supply mechanism to the intake hose. Thereafter, when the user releases the force on the first force application means, the second air supply mechanism is displaced from the discharge position to the intake position by the force from the second force application means. This displacement force is transmitted to the first air supply mechanism by the displacement force transmission means, and the first air supply mechanism is displaced from the intake position to the discharge position. As a result, air is discharged from the first air supply mechanism to the intake hose. In this way, with the underwater breathing apparatus according to the present invention, air can be supplied from the first air supply mechanism and the second air supply mechanism by a single operation (the action of applying force to the first force application means). Therefore, the configuration can be made more compact than when a single intake mechanism is provided. Moreover, the operation can be achieved by the simple action of applying force to the first force application means.

[0010] In one preferred embodiment of the underwater breathing apparatus according to the present invention, the first air supply mechanism and the second air supply mechanism each include a piston and a cylinder, the cylinder includes a cylindrical body and a head formed with an outlet port for allowing air inside the cylindrical body to flow into the intake hose, the first air supply mechanism and the second air supply mechanism are arranged with their longitudinal directions along the longitudinal axis of the housing and the outlet port facing upward, the head of the cylinder is fixed immovably relative to the housing, the cylindrical body of the cylinder is supported by the housing below the head so as to move closer to / away from the head as the piston moves forward / backward, the cylinder is configured so that when the cylindrical body is closest to the head, the interior of the cylindrical body does not communicate with the external space and when the cylindrical body is farthest from the head, the interior of the cylindrical body communicates with the external space, and the first force application means is a drawstring that applies a force to move the piston of the first air supply mechanism backward.

[0011] In this configuration, the user can shift the first air supply mechanism from the exhaust position to the intake position by pulling the pull cord, and shift the second air supply mechanism from the intake position to the exhaust position by releasing the pulling force of the pull cord, thus allowing the user to easily operate the underwater breathing apparatus.

[0012] In one preferred embodiment of the underwater breathing apparatus of the present invention, the second force application means is an elastic member which applies a downward tensile force to the piston of the second air supply mechanism, and the displacement force transmission means comprises a linear member connecting the lower end of the piston of the first air supply mechanism and the lower end of the piston of the second air supply mechanism, and a bridging member which is immovably disposed above the lower end of the most raised piston and which bridgingly bridges the linear member above the bridging member.

[0013] By configuring the second force application means and the displacement force transmission means in this way, a compact underwater breathing apparatus can be realized. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of underwater breathing equipment. [Diagram 2] FIG. 2 is a longitudinal cross-sectional view of the main body of the underwater breathing apparatus. [Diagram 3] 1A and 1B are longitudinal cross-sectional views of the cylinder near its head, where FIG. 1A shows a state in which the inside of the cylinder is not connected to the external space, and FIG. 1B shows a state in which the inside of the cylinder is connected to the external space. [Figure 4] FIG. 2 is a perspective view of the inner housing of the underwater breathing apparatus; [Diagram 5] 1 is a diagram showing the operation of the underwater breathing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An embodiment of the underwater breathing apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of the underwater breathing apparatus in this embodiment. The underwater breathing apparatus includes a main body A floating on the water surface, an intake hose B connected to the main body A, a mouthpiece C connected to the end of the intake hose B, and a pull string D. The intake hose B is for sending air from the main body A to a user underwater. The intake hose B can be a well-known one, and is preferably flexible and resistant to water pressure. The mouthpiece C can also be a well-known one, and is preferably one having an exhaust valve as disclosed in Patent Document 1, for example. The pull string D is for applying an external force (tensile force) from the user to the main body A, and will be described in detail later.

[0016] Next, the main body A of the underwater breathing apparatus in this embodiment will be described. FIG. 2 is a vertical cross-sectional view of the main body A, but the aspect ratio has been changed for ease of viewing. As shown in FIG. 2, the main body A includes a first air supply mechanism 1 and a second air supply mechanism 2 for supplying air to the intake hose B, and a housing 3 surrounding them. In this embodiment, the housing 3 includes an external housing 31 and an internal housing 32 surrounded by the external housing 31. The external housing 31 includes a cylindrical portion 31a and a substantially funnel-shaped portion 31b provided below the cylindrical portion 31a. A weight 31c is provided inside the funnel-shaped portion 31b. As shown in FIG. 1, this weight 31c is for floating the main body A on the water surface S in a position in which the longitudinal direction is substantially along the vertical direction. Therefore, the weight of the weight 31c is determined based on the weight and buoyancy of the main body A so as to achieve this purpose. Furthermore, funnel-shaped portion 31b and weight 31c are formed with insertion holes for inserting intake hose B and drawstring D. It is preferable to provide a cover (not shown) above external housing 31 to prevent water from entering and to allow air to be taken in.

[0017] The inner housing 32 is cylindrical and fixed to the outer housing 31. Specifically, the inner housing 32 is placed and fixed on the upper surface of the weight 31c. Inside the inner housing 32, there are provided a fixing member 5 for holding the first air supply mechanism 1 and the second air supply mechanism 2, a restricting member 6, and a plurality of support members 4 (see FIG. 4), which will be described in detail later.

[0018] Since the first air supply mechanism 1 and the second air supply mechanism 2 have the same configuration, only the first air supply mechanism 1 will be described here. The first air supply mechanism 1 includes a cylinder 11 and a piston 12. When the piston 12 advances (rises), air inside the cylinder 11 is discharged from an outlet 13a provided at the tip toward the intake hose B, and the first air supply mechanism 1 is surrounded by an internal housing 32 with its longitudinal direction aligned with the longitudinal direction of the main body A. The first air supply mechanism 1 is also provided so that the outlet 13a opens upward. In this embodiment, the ascent and descent of the piston 12 relative to the cylinder 11 correspond to the advance and retreat of the present invention, respectively. The ascent and descent states of the piston 12 correspond to the discharge posture and intake posture of the present invention.

[0019] In this embodiment, the cylinder 11 includes a cylindrical body 11a and a head 11b provided above the cylindrical body 11a. A substantially cylindrical convex portion 13 is provided at the tip of the head 11b, and the tip of the convex portion 13 serves as an outlet 13a. The cylindrical body 11a and the head 11b are not fixed, and the cylindrical body 11a can approach or move away from the head 11b in the longitudinal direction. Although the details will be described later, when the cylindrical body 11a moves away from the head 11b, air flows into the inside of the cylindrical body 11a.

[0020] The piston 12 includes a piston head 12a that slides longitudinally inside the cylindrical body 11a of the cylinder 11, and a rod-shaped piston rod 12b provided below the piston head 12a. As described below, the piston 12 moves forward and backward due to a force applied to the piston rod 12b. When the piston 12 moves forward / backward, the cylindrical body 11a moves together due to friction between the piston head 12a and the cylindrical body 11a, so that the cylindrical body 11a approaches / moves away from the head 11b.

[0021] FIG. 3 is a vertical cross-section of the cylinder 11 near the head 11b in this embodiment. FIG. 3(a) shows a state in which the cylinder 11a has descended to the lower limit and is separated from the inner bottom surface of the head 11b. On the other hand, FIG. 3(b) shows a state in which the cylinder 11a has ascended to the upper limit and is in close contact with the inner bottom surface of the head 11b. As shown in the figure, the upper end of the cylinder 11a and the lower end of the head 11b are formed with notches 14a and 14b, respectively. When the cylinder 11a has ascended to the upper limit, the notches 14a and 14b are not connected, and the upper end of the cylinder 11a is in close contact with the inner bottom surface of the head 11b. Therefore, as shown by the dashed-dotted arrow, the air inside the cylinder 11a is discharged from the discharge port 13a as the piston 12 advances (rises).

[0022] On the other hand, when the cylinder 11a is lowered to the lower limit and separated from the inner bottom surface of the head 11b, the notches 14a and 14b communicate with each other, and the inside of the cylinder 11a communicates with the outside space through this communication portion. Therefore, as the piston 12 moves backward, the air pressure inside the cylinder 11a decreases, and as shown by the dashed-dotted arrow, air is taken into the cylinder 11a through the notches 14a and 14b.

[0023] In this embodiment, the end of the intake hose B on the side of the main body A branches into two, each of which is connected to the head 11b of the first air supply mechanism 1 and the head 21b of the second air supply mechanism 2. As described later, the first air supply mechanism 1 and the second air supply mechanism 2 operate so that when one of them discharges air, the other supplies air, so that check valves b1 and b2 are provided at the branching portions of the intake hose B. The check valves b1 and b2 allow air to flow from the first air supply mechanism 1 and the second air supply mechanism 2 to the intake hose B and block air flow in the opposite direction. Specifically, when the first air supply mechanism 1 discharges air, the check valve b1 is "open" and the check valve b2 is "closed," so that air from the first air supply mechanism 1 flows only to the intake hose B. On the other hand, when the second air supply mechanism 2 discharges air, the check valve b2 is "open" and the check valve b1 is "closed", so that air from the second air supply mechanism 2 flows only through the intake hose B.

[0024] FIG. 4 is a perspective view of the internal housing 32 in this embodiment. As shown in the figure, a plurality of support members 4 that hold the cylindrical body 11a of the cylinder 11 and the cylindrical body 21a of the cylinder 21 along the longitudinal direction are fixed inside the internal housing 32. The support member 4 in this embodiment is substantially disk-shaped, and has two insertion holes 41 that insert and support the cylindrical body 11a and the cylindrical body 21a, and an insertion hole 42 that inserts the intake hose B. The diameter of the insertion hole 41 is substantially the same as the outer diameter of the cylindrical body 11a and the cylindrical body 21a. Note that the cylindrical body 11a and the cylindrical body 21a are simply inserted into the insertion hole 41 and are not fixed. Therefore, the cylindrical body 11a and the cylindrical body 21a can move forward and backward while maintaining their posture.

[0025] In addition, a fixed member 5 is fixed near the upper end of the internal housing 32. The fixed member 5 in this embodiment is substantially disk-shaped, and is formed with two insertion holes 51 through which the protrusions 13 and 23 are inserted, and an insertion hole 52 through which the intake hose B is inserted. The diameter of this insertion hole 51 is larger than the outer diameter of the protrusions 13 and 23, so that the tip of the branched part of the intake hose B can be inserted. In addition, the heads 11b and 21b are fixed to this fixed member 5. Therefore, when the cylindrical bodies 11a and 21a rise and come into contact with the heads 11b and 21b, respectively, further rise (forward movement) is restricted.

[0026] On the other hand, a regulating member 6 is fixed near the lower end of the internal housing 32. Specifically, the regulating member 6 is located slightly below the lower ends of the cylinders 11a and 21a in contact with the heads 11b and 21b. That is, when the cylinders 11a and 21a are in the most elevated state, a gap is formed between the lower ends and the upper surface of the regulating member 6. The regulating member 6 in this embodiment is substantially disk-shaped, and has two insertion holes 61 through which the piston rods 12b and 22b are inserted, and an insertion hole 62 through which the intake hose B is inserted. In this embodiment, the insertion hole 62 is formed not in the center of the regulating member 6, but at a position on the far side of the drawing. The diameter of the insertion hole 61 is larger than the diameter of the piston rods 12b and 22b, but smaller than the outer diameter of the cylinders 11a and 21a. Therefore, when the cylindrical body 11a and the cylindrical body 21a are lowered and their lower ends abut against the upper surface of the regulating member 6, further lowering (retraction) is restricted.

[0027] In this way, the ascent and descent of the cylindrical bodies 11a and 21a are regulated by the heads 11b and 21b fixed to the fixed member 5 and the regulating member 6, so that the cylindrical bodies 11a and 21a are allowed to move back and forth by the length of the gap.

[0028] A hole 63 having a rectangular shape in plan view is formed in the center of the regulating member 6, and a pulley 64 (an example of a bridging member in the present invention) is provided in this hole 63. The pulley 64 is for bridging a linear member 7 (described later) and for smoothly guiding the linear member 7.

[0029] As shown in FIG. 2, in this embodiment, the lower end of the piston rod 12b and the lower end of the piston rod 22b are connected by a linear member 7. The linear member 7, one end of which is fixed to the lower end of the piston rod 12b, is passed through a hole 63 of the regulating member 6 from below, and is stretched downward through the hole 63 after being hung from above on a pulley 64, and the other end of which is fixed to the lower end of the piston rod 22b. In this state, the linear member 7 is stretched without slack. This allows the movement of one piston to be transmitted to the other piston. Therefore, in this embodiment, the pulley 64 and the linear member 7 correspond to the displacement force transmission means of the present invention. In addition, it is preferable that the linear member 7 is a strong member that is not elastic and can easily transmit force.

[0030] 2, a pull cord D is connected to the lower end of the piston rod 12b. The user can pull this pull cord D to pull the piston 12 downward. In other words, the first air supply mechanism 1 in the discharge position can be displaced to the intake position. Therefore, in this embodiment, the pull cord D corresponds to the first force application means of the present invention.

[0031] On the other hand, the lower end of piston rod 22b is connected to weight 31c by elastic member 8. This elastic member 8 applies a downward pulling force to piston 22. In other words, elastic member 8 applies a force to maintain second air supply mechanism 2 in the intake position. Therefore, in this embodiment, elastic member 8 corresponds to the second force application means of the present invention.

[0032] Next, the operation of the underwater breathing apparatus when in use will be described with reference to Figure 5. Figure 5(a) shows the initial state in which no external force is acting from the user. In this state, the piston 22 is in an intake position, pulled downward by the elastic member 8. At this time, the force pulling the piston 22 downward is transmitted through the linear member 7 and pulley 64 and converted into a force pulling the piston 12 upward. As a result, the first air supply mechanism 1 is in a discharge position.

[0033] When the user pulls the drawstring D downward on the underwater breathing apparatus in this state, the piston 12 starts to move downward. At this time, the frictional force between the piston head 12a and the inner wall of the cylindrical body 11a causes the cylindrical body 11a to move downward until it abuts against the restricting member 6, and the upper end of the cylindrical body 11a moves away from the inner bottom surface of the head 11b. As a result, the notch 14a and the notch 14b communicate with each other, as shown in FIG. 3(a). Meanwhile, the piston 22 moves upward as the force that moves the piston 12 downward is transmitted through the linear member 7 and the pulley 64. When the piston 22 moves upward, the frictional force between the piston head 22a and the inner wall of the cylindrical body 21a also causes the cylindrical body 21a to rise until it abuts against the inner bottom surface of the head 21b. As a result, as shown in FIG. 3(b), the notch 24a and the notch 24b no longer communicate with each other (see FIG. 5(b)).

[0034] From this state, when the user further pulls the pullstring D downward, the piston 12 moves further downward. At this time, the downward movement of the cylinder 11a is restricted by the restricting member 6. As the piston 12 moves downward, the air pressure inside the cylinder 11a decreases, and air flows into the cylinder 11a from the surrounding external space through the communication part between the notches 14a and 14b. Meanwhile, the piston 22 moves further upward as the force that moves the piston 12 downward is transmitted through the linear member 7 and the pulley 64. At this time, the upward movement of the cylinder 21a is restricted by the head 23a. As the piston 22 rises, air is discharged from the discharge port 23a toward the intake hose B (see FIG. 5(c)). At this time, the elastic member 8 is in an elongated state.

[0035] When the second air supply mechanism 2 is displaced to the discharge position, the user loosens the drawstring D. As a result, the force acting on the first air supply mechanism 1 is eliminated, so that the elastic member 8 starts to contract and the piston 22 starts to move downward. At this time, the cylinder 21a also moves downward until it abuts against the restricting member 6 due to the frictional force between the piston head 22a and the inner wall of the cylinder 21a, and the upper end of the cylinder 21a moves away from the inner bottom surface of the head 21b. As a result, the notch 24a and the notch 24b communicate with each other, as shown in FIG. 3(a). Meanwhile, the piston 12 moves upward as the force that moves the piston 22 downward is transmitted through the linear member 7 and the pulley 64. When the piston 12 moves upward, the cylinder 11a also rises until it abuts against the head 11b due to the frictional force between the piston head 12a and the inner wall of the cylinder 11a. As a result, as shown in Fig. 3(b), the notches 14a and 14b do not communicate with each other (see Fig. 5(d)).

[0036] When the elastic member 8 further contracts from this state, the piston 22 moves further downward. At this time, the downward movement of the cylinder 21a is restricted by the restricting member 6. As the piston 22 moves downward, air flows in from the outside space through the communicating portion between the notches 24a and 24b. Meanwhile, the force that moves the piston 22 downward is transmitted to the piston 12, and the piston 12 moves further upward. At this time, the upward movement of the cylinder 11a is restricted by the head 11b. As the piston 12 rises, the air pressure inside the cylinder 11a increases, and air is discharged from the discharge port 13a toward the intake hose B (see FIG. 5(a)).

[0037] By repeating this operation, air is supplied to the user underwater. Thus, in the underwater breathing apparatus according to this embodiment, air is supplied from the first air supply mechanism 1 by pulling the pull cord D once, and air is supplied from the second air supply mechanism 2 by releasing the pulling force on the pull cord D.

[0038] The underwater breathing apparatus according to the present invention is not limited to the configuration in this embodiment, and can be modified as appropriate as long as the object of the present invention is achieved.

[0039] [Another embodiment] (1) An elastic member may be provided to exert a force to maintain the piston 12 in the ejection position.

[0040] (2) In the above embodiment, the first air intake mechanism 1 and the second air intake mechanism 2 are configured with a cylinder and a piston. However, instead of this, a pump or the like that is operated by an external force may be used.

[0041] (3) In the above embodiment, the cylinder body and head are provided with cutouts to connect the inside of the cylinder body to the outside space, and air is taken into the cylinder, but other configurations may be used to take air into the cylinder. For example, the position of the restricting member may be set slightly lower so that the upper end of the cylinder can be retracted below the lower end of the head. [Industrial Applicability]

[0042] The underwater breathing apparatus according to the present invention can be used for diving and underwater work in relatively shallow places. [Explanation of symbols]

[0043] A: Main body B: Intake hose b1: Check valve b2: check valve C: Mouthpiece D: Drawstring S: Water surface 1: First air supply mechanism 11: Cylinder 11a: Cylinder 11b: Head 12: Piston 13a: Discharge port 2: Second air supply mechanism 21: Cylinder 21a: Cylindrical body 21b: Head 22: Piston 23a: Discharge port 3: Housing 31: External housing 31c: Weight 32: Internal housing 64: Pulley (displacement force transmission means) 7: Linear member (displacement force transmission means) 8: Elastic member (second force application means)

Claims

1. an intake hose for delivering air to the underwater user; a housing having a longitudinal axis; a first air supply mechanism and a second air supply mechanism that are contained in the housing and supply the air to the intake hose, an insertion hole through which the intake hose is inserted is formed in a bottom portion of the housing; a weight is provided on a bottom of the housing to float the housing on the water surface with the longitudinal axis of the housing aligned substantially vertically; the first air supply mechanism and the second air supply mechanism supply the air to the air intake hose by repeatedly shifting between an air intake posture in which the air to be discharged is taken in and a discharge posture in which the air taken in is discharged; a first force application means for applying a force from the user to the first air supply mechanism to change the first air supply mechanism from the discharge position to the intake position; a second force application means for applying a force to the second air supply mechanism to maintain the second air supply mechanism in the intake position; a displacement force transmission means for transmitting a force causing one of the first air supply mechanism and the second air supply mechanism to displace from the exhaust position to the intake position to the other of the first air supply mechanism and the second air supply mechanism as a force causing the other of the first air supply mechanism and the second air supply mechanism to displace from the intake position to the exhaust position.

2. each of the first air supply mechanism and the second air supply mechanism includes a piston and a cylinder; The cylinder includes a cylindrical body and a head having an outlet formed therein for allowing air in the cylindrical body to flow into the intake hose, the first air supply mechanism and the second air supply mechanism are disposed such that their longitudinal directions are aligned with the longitudinal axis of the housing and their outlets are directed upward; The head of the cylinder is fixed immovably relative to the housing, a cylindrical body of the cylinder is supported by the housing below the head so as to move toward / away from the head as the piston moves forward / backward; the cylinder is configured such that an interior of the cylinder is not in communication with an external space when the cylinder is closest to the head, and such that an interior of the cylinder is in communication with an external space when the cylinder is farthest from the head, 2. Underwater breathing apparatus according to claim 1, wherein said first force applying means is a pull cord which applies a force to move said piston of said first air supply mechanism backward.

3. the second force application means is an elastic member that applies a downward pulling force to the piston of the second air supply mechanism, The displacement force transmission means is a linear member connecting a lower end of the piston of the first air supply mechanism and a lower end of the piston of the second air supply mechanism; 3. The underwater breathing apparatus according to claim 2, further comprising a bridge member which is immovably provided above a lower end of the piston at its highest position relative to the housing and which bridges the linear member above the bridge member.

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