Airbag

Abstract

To provide an airbag which enables improvement of workability when the airbag is attached to a seat.SOLUTION: An air bag 30 comprises: two films 31, 32; a first air chamber 51 and a second air chamber 52 that are individually provided between the two films 31, 32, expanded by air supplied thereto, and contracted by exhaust air; a first joint part 41 that joins the two films 31, 32 together so as to partition the first air chamber 51; and a second joint part 42 that joins the two films 31, 32 together so as to partition the second air chamber 52.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to bladders. [Background technology]

[0002] Vehicle seats with a lumbar support function have been known for some time. For example, a vehicle seat described in Patent Document 1 includes two air bladders provided in a seat back and a pump that supplies air to the two air bladders. The two air bladders are positioned offset in the vertical direction on the seat back. When air is supplied to the two air bladders from the pump in the vehicle seat, the two air bladders inflate toward the user's lumbar region. In this way, the vehicle seat supports the user's lumbar region with the two air bladders inflated to a size desired by the user. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 9,545,860 Summary of the Invention [Problem to be solved by the invention]

[0004] When assembling the vehicle seat described above, it is necessary to attach two separately manufactured air bags to two mounting portions of the vehicle seat, respectively. Therefore, there is still room for improvement in terms of improving the workability when attaching the air bags to the seat. [Means for solving the problem]

[0005] The air bag that solves the above problem is provided in the seat back of a seat and supports the lower back of a user seated in the seat, and comprises two films, a first air chamber and a second air chamber that are individually provided between the two films, the first air chamber and the second air chamber expanding when air is supplied and contracting when air is exhausted, a first joint that joins the two films to define the first air chamber, and a second joint that joins the two films to define the second air chamber. [Effects of the Invention]

[0006] The air bag can improve workability when attaching the seat. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a seat equipped with a pneumatic system according to a first embodiment. [Figure 2] FIG. 2 is a front view of the air bag of the pneumatic system of the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. [Figure 4] FIG. 4 is a perspective view of the air bag of the first embodiment when inflated. [Figure 5] FIG. 5 is a front view of the air bag of the second embodiment. [Figure 6] FIG. 6 is a perspective view of the air bag of the second embodiment when inflated. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) A first embodiment of a seat equipped with an air bag will be described below. <Configuration of the first embodiment> As shown in FIG. 1 , the seat 10 includes a seat cushion 11, a seat back 12, and an air pressure system 20. The seat 10 is a vehicle seat used, for example, in the driver's seat, passenger seat, or rear seat of a vehicle. In another embodiment, the seat 10 may be a massage seat used in facilities or the like. The seat cushion 11 is a portion that mainly supports the buttocks and thighs of a user seated in the seat 10. The seat back 12 is a portion that mainly supports the lower back and back of a user seated in the seat 10.

[0009] <Air Pressure System 20> The pneumatic system 20 includes an air bag 30, a pump 21, a connecting flow path 22, a first branch flow path 23, a second branch flow path 24, a first switching valve 25, a second switching valve 26, an operating unit 27, and a control unit 28.

[0010] <Air bag 30> The air bag 30 is built into the seat back 12 in a portion that comes into contact with the user's lower back. In light of this, the following description will describe the orientation of the air bag 30 in accordance with the orientation when it is built into the seat back 12. That is, the air bag 30 will be described using the width direction and up-down direction of the seat back 12. Here, because the angle between the seat cushion 11 and the seat back 12 is not necessarily perpendicular, the up-down direction of the seat back 12 does not necessarily correspond to the up-down direction of the vehicle. Furthermore, because the installation direction of the seat 10 is not necessarily toward the front of the vehicle, the width direction of the seat back 12 does not necessarily correspond to the width direction of the vehicle.

[0011] 2 and 3, air bag 30 includes two films 31 and 32. Air bag 30 also includes a first joint portion 41, a second joint portion 42, a first air chamber 51, a second air chamber 52, a first connection port 53, a second connection port 54, and two engagement holes 55.

[0012] The two films 31, 32 are made of a thermoplastic resin such as polyurethane. The two films 31, 32 are rectangular when viewed in the thickness direction. The two films 31, 32 are the same size. The two films 31, 32 overlap in the thickness direction. The thickness direction of the two films 31, 32 is perpendicular to both the up-down direction and the width direction of the air bag 30.

[0013] The first joint 41 joins the two films 31, 32 together to define the first air chamber 51. Similarly, the second joint 42 joins the two films 31, 32 together to define the second air chamber 52. The first joint 41 and the second joint 42 partially overlap. In the following description, the overlapping portion of the first joint 41 and the second joint 42 will be referred to as the "common joint 43."

[0014] The first bonding portion 41 and the second bonding portion 42 are formed by high-frequency welding the two films 31, 32. In other embodiments, the first bonding portion 41 and the second bonding portion 42 may be formed by heat welding or laser welding the two films 31, 32. Furthermore, the first bonding portion 41 and the second bonding portion 42 may be formed by bonding the two films 31, 32 with an adhesive or the like.

[0015] The first joint portion 41 has two first side portions 41L and 41R, a first bottom portion 41D, and a common joint portion 43. The two first side portions 41L, 41R are located near both ends of the air bag 30 in the width direction. Each of the first side portions 41L, 41R includes a linear portion 411 that is linear and two curved portions 412, 413 that are arc-shaped. The longitudinal direction of the linear portion 411 is the up-down direction. One of the curved portions 412 is connected to the lower end of the linear portion 411. The one of the curved portions 412 curves downward from the lower end of the linear portion 411 toward the center of the air bag 30 in the width direction. The other curved portion 413 is connected to the upper end of the linear portion 411. The other curved portion 413 curves upward from the upper end of the linear portion 411 toward the center of the air bag 30 in the width direction. The curved portion 413 of the first side portion 41R includes a first connection port 53 to which the first branch flow path 23 is connected. In the curved portion 413 of the first side portion 41R, the two films 31 and 32 are not joined together in the portion where the first connection port 53 is provided.

[0016] The first bottom portion 41D is located near the lower end of the air bag 30. The first bottom portion 41D includes two linear portions 414, 415 and a curved portion 416 that curves relative to the linear portions 414, 415. The longitudinal direction of the two linear portions 414, 415 is the width direction. One linear portion 414 connects to the curved portion 412 of the first side portion 41L, and the other linear portion 415 connects to the curved portion 412 of the first side portion 41R. The curved portion 416 connects the two linear portions 414, 415 in the width direction. The curved portion 416 is curved so that its central portion in the width direction is located higher than both end portions in the width direction. More specifically, both side portions of the curved portion 416 in the width direction are curved so as to be convex downward, while the central portion of the curved portion 416 in the width direction is curved so as to be convex upward. In this regard, if a curve is drawn along curved portion 416, it can be said that the curve includes two inflection points in the longitudinal direction.

[0017] The second joint portion 42 has two second side portions 42L and 42R, a second upper portion 42U, and a common joint portion 43. The two second side portions 42L, 42R are located near both ends of the air bag 30 in the width direction. The second side portions 42L, 42R include a straight portion 421 that is linear and two curved portions 422, 423 that are arc-shaped. The longitudinal direction of the straight portion 421 is the up-down direction. The straight portion 421 of the second side portion 42L is located on an extension of the straight portion 411 of the first side portion 41L, and the straight portion 421 of the second side portion 42R is located on an extension of the straight portion 411 of the first side portion 41R. The straight portion 421 of the second side portions 42L, 42R is longer than the straight portion 411 of the first side portions 41L, 41R. One of the curved portions 422 is connected to the lower end of the straight portion 421. One curved portion 422 curves downward from the lower end of straight portion 421 toward the center in the width direction of air bag 30. The other curved portion 423 is connected to the upper end of straight portion 421. The other curved portion 423 curves upward from the upper end of straight portion 421 toward the center in the width direction of air bag 30. Curved portion 423 of second side portion 42R includes second connection port 54 to which second branch flow path 24 is connected. In curved portion 423 of second side portion 42R, the two films 31, 32 are not joined at the portion where second connection port 54 is provided.

[0018] The second upper portion 42U is located near the upper end of the air bag 30. The second upper portion 42U is linear. The longitudinal direction of the second upper portion 42U is the width direction. The second upper portion 42U connects the curved portion 423 of the second side portion 42L and the curved portion 423 of the second side portion 42R in the width direction.

[0019] The common joint 43 includes two linear portions 431 and 432 and a curved portion 433 that curves relative to the linear portions 431 and 432. The common joint 43 is located between the first bottom portion 41D and the second upper portion 42U.

[0020] The longitudinal direction of the two straight portions 431, 432 is the width direction. One straight portion 431 is connected to the curved portion 413 of the first side portion 41L and the curved portion 423 of the second side portion 42L. In other words, the curved portion 413 of the first side portion 41L and the curved portion 422 of the second side portion 42L branch off from one straight portion 431. The other straight portion 432 is connected to the curved portion 413 of the first side portion 41R and the curved portion 422 of the second side portion 42R. In other words, the curved portion 413 of the first side portion 41R and the curved portion 422 of the second side portion 42R branch off from the other straight portion 432.

[0021] The curved portion 433 connects the two straight portions 431, 432 in the width direction. The curved portion 433 is curved so that its center in the width direction is located higher than both end portions in the width direction. When the two films 31, 32 are viewed in the thickness direction, the common joint portion 43 is curved so that the first air chamber 51 is convex toward the second air chamber 52. Both side portions of the curved portion 433 in the width direction are curved so as to be convex downward, while the center portion of the curved portion 433 in the width direction is curved so as to be convex upward. In this regard, if a curve is drawn along the curved portion 433, it can be said that the curve includes two inflection points in the longitudinal direction.

[0022] In the vertical direction, the distance between the straight portion 414 of the first bottom 41D and the straight portion 431 of the common joint 43, the distance between the straight portion 415 of the first bottom 41D and the straight portion 432 of the common joint 43, and the distance between the center of the curved portion 416 of the first bottom 41D and the center of the curved portion 433 of the common joint 43 are all equal. Similarly, in the vertical direction, the distance between the straight portion 431 of the second upper portion 42U and the common joint 43 is equal to the distance between the straight portion 432 of the second upper portion 42U and the common joint 43. On the other hand, in the vertical direction, the distance between the straight portions 414, 415 of the first bottom 41D and the straight portions 431, 432 of the common joint 43 is narrower than the distance between the straight portions 431, 432 of the second upper portion 42U and the common joint 43. In addition, in the width direction, the distance between the two first side portions 41L, 41R is equal to the distance between the two second side portions 42L, 42R.

[0023] A first left inscribed circle C1L, a first right inscribed circle C1R, and a first central inscribed circle C1C can be drawn inside the first joint 41. The first left inscribed circle C1L is tangent to the straight portion 411 of the first side portion 41L, the curved portion 416 of the first bottom portion 41D, and the straight portion 431 of the common joint 43. The first right inscribed circle C1R is tangent to the straight portion 411 of the first side portion 41R, the curved portion 416 of the first bottom portion 41D, and the straight portion 432 of the common joint 43. The first central inscribed circle C1C is tangent to the curved portion 416 of the first bottom portion 41D and the curved portion 433 of the common joint 43. The first left inscribed circle C1L, the first right inscribed circle C1R, and the first central inscribed circle C1C are all circles with the same inner diameter.

[0024] A second left inscribed circle C2L and a second right inscribed circle C2R can be drawn inside the second joint 42. The second left inscribed circle C2L is tangent to the straight portion 421 of the second side portion 42L, the second upper portion 42U, and the curved portion 433 of the common joint 43. The second right inscribed circle C2R is tangent to the straight portion 421 of the second side portion 42R, the second upper portion 42U, and the curved portion 433 of the common joint 43. The second left inscribed circle C2L and the second right inscribed circle C2R are circles with equal inner diameters. However, the inner diameters of the second left inscribed circle C2L and the second right inscribed circle C2R are larger than the inner diameters of the first left inscribed circle C1L, the first right inscribed circle C1R, and the first central inscribed circle C1C.

[0025] The center of the first central inscribed circle C1C is located between the first left inscribed circle C1L and the first right inscribed circle C1R in the width direction, and between the second left inscribed circle C2L and the second right inscribed circle C2R. In the vertical direction, the center of the first central inscribed circle C1C is located between a line segment connecting the centers of the first left inscribed circle C1L and the first right inscribed circle C1R and a line segment connecting the centers of the second left inscribed circle C2L and the second right inscribed circle C2R. In addition, the lower end of the first central inscribed circle C1C is located below the line segment connecting the centers of the first left inscribed circle C1L and the first right inscribed circle C1R in the vertical direction. Meanwhile, the upper end of the first central inscribed circle C1C is located below the line segment connecting the centers of the second left inscribed circle C2L and the second right inscribed circle C2R in the vertical direction.

[0026] The first air chamber 51 and the second air chamber 52 are vertically separated by the common joint 43. In this respect, the first air chamber 51 and the second air chamber 52 are adjacent to each other in the vertical direction. In other words, the vertical direction is the "adjacent direction." Because the common joint 43 curves upward, the first air chamber 51 partially overlaps with the second air chamber 52 in both the vertical direction and the width direction. More specifically, when viewed in the thickness direction of the two films 31, 32, the first air chamber 51 has a shape such that its central portion in the width direction is convex toward the second air chamber 52. In other words, the second air chamber 52 has a shape such that its central portion in the width direction is concave with respect to the first air chamber 51. Thus, the portion of the first air chamber 51 that is convex toward the second air chamber 52 is sandwiched between the second air chambers 52 in the width direction.

[0027] The first air chamber 51 expands when air is supplied through the first connection port 53, and contracts when air is exhausted through the first connection port 53. Similarly, the second air chamber 52 expands when air is supplied through the second connection port 54, and contracts when air is exhausted through the second connection port 54. In this way, the first air chamber 51 and the second air chamber 52 are independent air chambers that are provided separately. For this reason, it is possible to supply air to one air chamber and exhaust air from the other air chamber, or to supply more air to one air chamber than to the other air chamber.

[0028] As shown in FIG. 4, when the first air chamber 51 inflates, the portions corresponding to the first left inscribed circle C1L, the first right inscribed circle C1R, and the first central inscribed circle C1C primarily inflate. Similarly, when the second air chamber 52 inflates, the portions corresponding to the second left inscribed circle C2L and the second right inscribed circle C2R and the central portion in the width direction primarily inflate. Here, the amount of inflation of the air bag 30 in the thickness direction of the two films 31, 32 is referred to as the stroke amount. In this case, in the first air chamber 51, the centers of the first left inscribed circle C1L, the first right inscribed circle C1R, and the first central inscribed circle C1C have larger stroke amounts than the other portions. Similarly, in the second air chamber 52, the centers of the second left inscribed circle C2L and the second right inscribed circle C2R have larger stroke amounts than the other portions.

[0029] As shown in FIG. 2, two engagement holes 55 are provided near the upper ends of the two films 31, 32. The two engagement holes 55 are provided with a gap between them in the width direction. The two engagement holes 55 penetrate the two films 31, 32 in the thickness direction. The two engagement holes 55 are portions that are engaged with engagement portions provided on the sheet 10 when the air bag 30 is attached to the sheet 10. In this regard, the shape and number of the two engagement holes 55 should be determined in relation to the attachment portion on the sheet 10.

[0030] <Pump 21> Although not shown in Fig. 1, the pump 21 has a drive source such as an electric motor. The pump 21 delivers air based on power transmitted from the drive source. The pump 21 may be a reciprocating pump such as a piston pump, or may be a rotary pump.

[0031] <Flow path> The connection flow path 22, the first branch flow path 23, and the second branch flow path 24 are formed of elastomer tubes having appropriate elasticity. The connection flow path 22, the first branch flow path 23, and the second branch flow path 24 may be formed by laminating flow path-forming members having grooves. The upstream end of the connection flow path 22 is connected to the pump 21. The downstream end of the connection flow path 22 is connected to the upstream end of the first branch flow path 23 and the upstream end of the second branch flow path 24. At this point, the first branch flow path 23 and the second branch flow path 24 branch off from the downstream end of the connection flow path 22. The downstream end of the first branch flow path 23 is connected to the first connection port 53 of the first air chamber 51, and the downstream end of the second branch flow path 24 is connected to the second connection port 54 of the second air chamber 52. Here, the downstream end of the first branch flow path 23 may be detachably connected to the first connection port 53 of the first air chamber 51 via a connector or the like. The downstream end of first branch flow path 23 may be undetachably connected to first connection port 53 of first air chamber 51 by welding or the like. The same applies to the downstream end of second branch flow path 24 in terms of its relationship with second connection port 54.

[0032] <Switching valve> The first switching valve 25 is provided in the first branch flow path 23, and the second switching valve 26 is provided in the second branch flow path 24. The first switching valve 25 and the second switching valve 26 are, for example, solenoid valves. The first switching valve 25 can be configured as a single solenoid valve, or can be configured as two or more solenoid valves. The same applies to the second switching valve 26.

[0033] First selector valve 25 switches between an air supply state in which first air chamber 51 of air bladder 30 is connected to pump 21, an exhaust state in which first air chamber 51 of air bladder 30 is connected to the outside air, and a shut-off state in which first air chamber 51 of air bladder 30 is not connected to either pump 21 or the outside air. Similarly, second selector valve 26 switches between an air supply state in which second air chamber 52 of air bladder 30 is connected to pump 21, an exhaust state in which second air chamber 52 of air bladder 30 is connected to the outside air, and a shut-off state in which second air chamber 52 of air bladder 30 is not connected to either pump 21 or the outside air. When first selector valve 25 is in the air supply state, air can be supplied to first air chamber 51 by driving pump 21. When first selector valve 25 is in the exhaust state, air can be discharged from first air chamber 51. When first selector valve 25 is in the shut-off state, air cannot be supplied to or discharged from first air chamber 51. The same applies to the second switching valve 26 in terms of its relationship with the second air chamber 52. When the first switching valve 25 and the second switching valve 26 are configured as solenoid valves, it is preferable that the first switching valve 25 and the second switching valve 26 be in a shut-off state when not energized.

[0034] <Operation section 27> Operation unit 27 is operated by the user to instruct the inflation and deflation of air bladder 30. Operation unit 27 may be a group of switches provided on the vehicle's instrument panel or the side of seat 10. Operation unit 27 may also be the user's smartphone. Operation unit 27 has multiple switches that indicate the direction in which air bladder 30 moves the position at which it supports the user's lower back (hereinafter also referred to as the "support position"). More specifically, operation unit 27 has an FR switch for moving the support position forward, an RR switch for moving the support position rearward, an UP switch for moving the support position upward, and a DN switch for moving the support position downward. Here, the front-rear direction, which is the direction in which the support position moves, is the thickness direction of seat back 12.

[0035] <Control unit 28> Control unit 28 is an electronic control device equipped with a CPU and memory. In control unit 28, the CPU executes a program stored in the memory to control the controlled object. More specifically, control unit 28 controls pump 21, first switching valve 25, and second switching valve 26 based on an operation signal transmitted from operation unit 27. In this way, control unit 28 controls the inflation and deflation of air bag 30. This will be explained in detail below.

[0036] When the FR switch is operated, the control unit 28 drives the pump 21. Next, the control unit 28 switches the first switching valve 25 to the air supply state and the second switching valve 26 to the air supply state. In this way, the control unit 28 supplies air to the first air chamber 51 and the second air chamber 52. As a result, the first air chamber 51 and the second air chamber 52 are inflated, and the support position moves forward. That is, the air bladder 30 moves closer to the user's waist, or the force with which the air bladder 30 presses against the user's waist increases. When the operation of the FR switch is terminated, the control unit 28 stops driving the pump 21. Furthermore, the control unit 28 switches the first switching valve 25 to the shut-off state and the second switching valve 26 to the shut-off state. As a result, the support position is maintained in the state in which it has moved forward.

[0037] When the RR switch is operated, the control unit 28 switches the first switching valve 25 to the exhaust state and switches the second switching valve 26 to the exhaust state. In this way, the control unit 28 discharges air from the first air chamber 51 and discharges air from the second air chamber 52. As a result, the first air chamber 51 and the second air chamber 52 contract, causing the support position to move rearward. In other words, the air bag 30 moves away from the user's waist, or the force with which the air bag 30 presses against the user's waist decreases. When the operation of the RR switch is terminated, the control unit 28 switches the first switching valve 25 to the shutoff state and switches the second switching valve 26 to the shutoff state. As a result, the state in which the support position has moved rearward is maintained.

[0038] When the UP switch is operated, controller 28 drives pump 21. Next, controller 28 switches first switching valve 25 to the exhaust state and second switching valve 26 to the intake state. In this way, controller 28 exhausts air from first air chamber 51 and supplies air to second air chamber 52. As a result, first air chamber 51 contracts while second air chamber 52 expands, causing the support position to move upward. In other words, the portion of air bladder 30 that comes into contact with the user moves upward. When the operation of the UP switch is terminated, controller 28 stops driving pump 21. Furthermore, controller 28 switches first switching valve 25 to the shutoff state and second switching valve 26 to the shutoff state. As a result, the state in which the support position has moved upward is maintained. Here, the portion of air bladder 30 that comes into contact with the user refers to the portion of air bladder 30 that comes into contact with the user via the cover of seat back 12.

[0039] When the DN switch is operated, control unit 28 drives pump 21. Next, control unit 28 switches first switching valve 25 to the air supply state and second switching valve 26 to the air exhaust state. In this way, control unit 28 supplies air to first air chamber 51 and discharges air from second air chamber 52. As a result, first air chamber 51 expands while second air chamber 52 contracts, causing the support position to move downward. In other words, the portion of air bladder 30 that comes into contact with the user moves downward. When the operation of the DN switch is terminated, control unit 28 stops driving pump 21. Furthermore, control unit 28 switches first switching valve 25 to the shutoff state and second switching valve 26 to the shutoff state. As a result, the support position is maintained in the state in which it has moved downward.

[0040] In this way, the support position of the air pressure system 20 can be moved in both the front-to-back direction and the up-to-down direction. In this respect, the air pressure system 20 can be said to achieve a 4-way lumbar support function.

[0041] <Actions and Effects of the First Embodiment> (1) In air bag 30, first air chamber 51 and second air chamber 52 are formed by joining two films 31, 32 at first joining portion 41 and second joining portion 42. That is, air bag 30 has two air chambers 51, 52. Therefore, when attaching air bag 30 of the first embodiment to seat back 12, the worker's work efficiency is improved compared to when attaching two air bags each having one air chamber to seat back 12.

[0042] (2) As shown in FIG. 2, three inscribed circles C1L, C1R, and C1C with equal inner diameters can be drawn inside the first air chamber 51, in other words, inside the first joint 41. Similarly, two inscribed circles C2L and C2R with equal inner diameters can be drawn inside the second air chamber 52, in other words, inside the second joint 42. Therefore, as shown in FIG. 4, when air is supplied to the first air chamber 51 and the second air chamber 52, the portions of the first air chamber 51 corresponding to the three inscribed circles C1L, C1R, and C1C expand significantly, and the portions of the second air chamber 52 corresponding to the two inscribed circles C2L and C2R expand significantly. In this way, the air bag 30 can ensure a sufficient stroke.

[0043] (3) The first bonding portion 41 and the second bonding portion 42 have a common bonding portion 43. Therefore, compared to a case where the first bonding portion 41 and the second bonding portion 42 do not have the common bonding portion 43, the bonding area of ​​the two films 31, 32 is smaller, and the effort required to bond the two films 31, 32 is reduced.

[0044] (4) Consider an air bag of a comparative example in which the common joint 43 extends linearly in the width direction of the seat back 12. The air bag of this comparative example has a portion that cannot be inflated in the vertical direction. In other words, the air bag of the comparative example has a portion that cannot support the user's lumbar region in the vertical direction. In contrast, in the air bag 30 of the first embodiment, the common joint 43 is curved so that the first air chamber 51 is convex toward the second air chamber 52. In other words, the air bag 30 has few portions that cannot support the user's lumbar region in the vertical direction. Therefore, the air bag 30 can support the user's lumbar region in the manner desired by the user.

[0045] (5) The common joint 43 of the air bag 30 is curved so that the central portion in the width direction of the first air chamber 51 is convex toward the second air chamber 52. Therefore, the air pressure system 20 can inflate and deflate the first air chamber 51 and the second air chamber 52 symmetrically in the width direction.

[0046] (6) When the user operates the UP switch or DN switch of operation unit 27, one air chamber of air bag 30 inflates and the other air chamber deflates. In this regard, in air bag 30 of the first embodiment, the center in the width direction of first air chamber 51 overlaps in the vertical direction with both ends in the width direction of second air chamber 52. Therefore, even though pneumatic system 20 actually only inflates one air chamber of air bag 30 and deflates the other air chamber, it is possible to give the user the sensation that the support position of air bag 30 is moving in the vertical direction. Therefore, pneumatic system 20 can provide a comfortable feel to the user.

[0047] (7) In the air bag 30, the first connection port 53 is provided in the curved portion of the first joint 41. Therefore, even when the first air chamber 51 expands, stress is less likely to concentrate around the first connection port 53. Similarly, the second connection port 54 is provided in the curved portion of the second joint 42. Therefore, even when the second air chamber 52 expands, stress is less likely to concentrate around the second connection port 54. In this way, the air bag 30 can improve the durability of the areas around the first connection port 53 and the second connection port 54.

[0048] (Second embodiment) An air bag 30A according to the second embodiment will now be described. When compared with the air bag 30 according to the first embodiment, the air bag 30A according to the second embodiment differs mainly in the shapes of the first joint portion 41 and the second joint portion 42. Therefore, hereinafter, components common to the first embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted or simplified.

[0049] <Air bag 30A> 5, air bag 30A includes two films 31 and 32. Air bag 30A also includes a first joining portion 61, a second joining portion 62, a first air chamber 71, a second air chamber 72, a first connection port 73, a second connection port 74, and two engagement holes 55.

[0050] The first bonding portion 61 bonds the two films 31, 32 together to define the first air chamber 71. Similarly, the second bonding portion 62 bonds the two films 31, 32 together to define the second air chamber 72. In the first embodiment, the first bonding portion 61 and the second bonding portion 62 partially overlap. In the following description, the overlapping portion of the first bonding portion 61 and the second bonding portion 62 is referred to as the "common bonding portion 63."

[0051] The first joint portion 61 has two first side portions 61L and 61R, a first bottom portion 61D, and a common joint portion 63. The two first side portions 61L, 61R are located near both ends in the width direction of the air bag 30A. The first side portions 61L, 61R are semicircular arc-shaped. The first side portion 61R includes a first connection port 73 to which the first branch flow path 23 is connected. The two films 31, 32 are not joined at the portion of the first side portion 61R where the first connection port 73 is provided. The first bottom portion 61D is located near the lower end of the air bag 30A. The first bottom portion 61D connects the lower end of the first side portion 61L and the lower end of the first side portion 61R in the width direction. The first bottom portion 61D is curved so that its center in the width direction is located higher than both end portions in the width direction. More specifically, both side portions in the width direction of the first bottom portion 61D are curved so as to be convex downward, while the center portion in the width direction of the first bottom portion 61D is curved so as to be convex upward. In this regard, when a curve is drawn along the first bottom portion 61D, it can be said that the curve includes two inflection points in the longitudinal direction.

[0052] The second joint portion 62 has two second side portions 62L and 62R, a second upper portion 62U, and a common joint portion 63. The two second side portions 62L, 62R are located near both ends of the air bag 30A in the width direction. The second side portions 62L, 62R are semicircular arc-shaped. The second side portion 62R includes a second connection port 74 to which the second branch flow path 24 is connected. The two films 31, 32 are not joined to the portion of the second side portion 62R where the second connection port 74 is provided. The second upper portion 62U is located near the upper end of the air bag 30A. The second upper portion 62U is linear. The longitudinal direction of the second upper portion 62U is the width direction. The second upper portion 62U connects the upper end of the second side portion 62L and the upper end of the second side portion 62R in the width direction.

[0053] The common joint 63 is located between the first bottom portion 61D and the second top portion 62U. The common joint 63 extends in a curved manner in the width direction. A first longitudinal end of the common joint 63 connects to the upper end of the first side portion 61L and the lower end of the second side portion 62L. A second longitudinal end of the common joint 63 connects to the upper end of the first side portion 61R and the lower end of the second side portion 62R. The common joint 63 is curved so that its central portion in the width direction is located higher than both width direction ends. More specifically, both width direction ends of the common joint 63 are curved so as to be convex downward, while the width direction central portion of the common joint 63 is curved so as to be convex upward. In this regard, if a curve is drawn along the common joint 63, it can be said that the curve includes two inflection points in the longitudinal direction.

[0054] A first left inscribed circle C1L, a first right inscribed circle C1R, and a first central inscribed circle C1C can be drawn inside the first joint 61. The first left inscribed circle C1L is tangent to the first side portion 61L and the first bottom portion 61D. The first right inscribed circle C1R is tangent to the first side portion 61R and the first bottom portion 61D. The first central inscribed circle C1C is tangent to the first bottom portion 61D and the common joint 63. The first left inscribed circle C1L, the first right inscribed circle C1R, and the first central inscribed circle C1C are circles with equal inner diameters.

[0055] A second left inscribed circle C2L and a second right inscribed circle C2R can be drawn inside the second joint 62. The second left inscribed circle C2L is tangent to the second side portion 62L and the common joint 63. The second right inscribed circle C2R is tangent to the second side portion 62R and the common joint 63. The second left inscribed circle C2L and the second right inscribed circle C2R are circles with equal inner diameters. However, the inner diameters of the second left inscribed circle C2L and the second right inscribed circle C2R are larger than the inner diameters of the first left inscribed circle C1L, the first right inscribed circle C1R, and the first central inscribed circle C1C.

[0056] The center of the first central inscribed circle C1C is located between the first left inscribed circle C1L and the first right inscribed circle C1R in the width direction, and between the second left inscribed circle C2L and the second right inscribed circle C2R. In the vertical direction, the center of the first central inscribed circle C1C is located between a line segment connecting the centers of the first left inscribed circle C1L and the first right inscribed circle C1R and a line segment connecting the centers of the second left inscribed circle C2L and the second right inscribed circle C2R. In addition, the lower end of the first central inscribed circle C1C is located below the line segment connecting the centers of the first left inscribed circle C1L and the first right inscribed circle C1R in the vertical direction. Meanwhile, the upper end of the first central inscribed circle C1C is located below the line segment connecting the centers of the second left inscribed circle C2L and the second right inscribed circle C2R in the vertical direction.

[0057] The first air chamber 71 and the second air chamber 72 are vertically separated by the common joint 63. In this respect, the first air chamber 71 and the second air chamber 72 are adjacent to each other in the vertical direction. Because the common joint 63 is curved upward, the first air chamber 71 partially overlaps with the second air chamber 72 in both the vertical direction and the width direction. More specifically, the first air chamber 71 has a shape such that the central portion in the width direction is convex toward the second air chamber 72. In other words, the central portion in the width direction of the second air chamber 72 has a shape such that it is concave with respect to the first air chamber 71. In this way, the portion of the first air chamber 71 that is convex toward the second air chamber 72 is sandwiched between the second air chamber 72 in the width direction.

[0058] The first air chamber 71 expands when air is supplied through the first connection port 73, and contracts when air is exhausted through the first connection port 73. Similarly, the second air chamber 72 expands when air is supplied through the second connection port 74, and contracts when air is exhausted through the second connection port 74. In this way, the first air chamber 71 and the second air chamber 72 are separate, independent air chambers.

[0059] As shown in FIG. 6, when the first air chamber 71 inflates, the portions corresponding to the first left inscribed circle C1L, the first right inscribed circle C1R, and the first central inscribed circle C1C primarily inflate. Similarly, when the second air chamber 72 inflates, the portions corresponding to the second left inscribed circle C2L, the second right inscribed circle C2R, and the middle portion in the width direction primarily inflate. In other words, in the first air chamber 71, the centers of the first left inscribed circle C1L, the first right inscribed circle C1R, and the first central inscribed circle C1C have a larger stroke than the other portions. Similarly, in the second air chamber 72, the centers of the second left inscribed circle C2L and the second right inscribed circle C2R have a larger stroke than the other portions.

[0060] <Actions and Effects of the Second Embodiment> The second embodiment can achieve the same functions and effects as the first embodiment. Furthermore, in air bag 30A, first side portion 61R of first joint portion 61 and second side portion 62R of second joint portion 62 are arc-shaped. Therefore, even under the constraint that first connection port 73 and second connection port 74 must be formed in the arc-shaped portion of the joint, the degree of freedom in the formation positions of first connection port 73 and second connection port 74 is increased.

[0061] <Example of change> The above embodiment can be modified as follows: The first embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0062] In the first embodiment, the air bag 30 may further include a third joint that defines a third air chamber, in addition to the first joint 41 that defines the first air chamber 51 and the second joint 42 that defines the second air chamber 52. In this case, the third air chamber is preferably adjacent to the second air chamber 52. The second joint 42 and the third joint may have a second common joint that defines both the second air chamber 52 and the third air chamber at the boundary between them. In other words, the second joint 42 and the third joint may share the second common joint. In this case, the second common joint may have the same shape as the common joint 43. Furthermore, the air bag 30 may include joints that define four or more air chambers. This is the same in the second embodiment.

[0063] In the air bag 30 of the first embodiment, the first bottom portion 41D of the first joint portion 41 may extend linearly in the width direction, similar to the second upper portion 42U of the second joint portion 42. Furthermore, the common joint portion 43 may extend linearly in the width direction, similar to the second upper portion 42U of the second joint portion 42. The same applies to the second embodiment.

[0064] In the air bag 30 of the first embodiment, the second upper portion 42U of the second joint portion 42 may be curved so that the central portion in the width direction approaches the common joint portion 43. The same applies to the second embodiment.

[0065] In the air bag 30 of the first embodiment, the first joint 41 may be composed of only a linear portion. Similarly, the second joint 42 may be composed of only a linear portion. Furthermore, the common joint 43 may be composed of only a linear portion.

[0066] In the first embodiment, the air bag 30 does not have to have a common joint 43. That is, the first joint 41 and the second joint 42 may be separate in the air bag 30. Even in this case, it is preferable that the first joint 41 and the second joint 42 are curved so that the center in the width direction of the first air chamber 51 is convex with respect to the center in the width direction of the second air chamber 52. That is, it is preferable that the upper end of the first air chamber 51 is located higher than the lower end of the second air chamber 52. The same applies to the second embodiment.

[0067] In the first embodiment, the common joint 43 has one curved portion 433. Therefore, there is only one portion that protrudes from the first air chamber 51 toward the second air chamber 52. In contrast, in a modified example, the common joint 43 may have two or more curved portions. In other words, there may be two or more portions that protrude from the first air chamber 51 toward the second air chamber 52. The same applies to the second embodiment.

[0068] In the air bag 30 of the first embodiment, the first connection port 53 may be provided in a linearly extending portion of the first joint portion 41. The same applies to the second connection port . In the air bag 30 of the first embodiment, the first connection port 53 may be provided in a portion other than the first joint portion 41. For example, the first connection port 53 may be provided in one of the two films 31, 32. The same applies to the second connection port 54 in the second embodiment.

[0069] In the air bag 30 of the first embodiment, the inner diameters of the second left inscribed circle C2L and the second right inscribed circle C2R may be equal to or smaller than the inner diameters of the first left inscribed circle C1L, the first right inscribed circle C1R, and the first central inscribed circle C1C. The same applies to the second embodiment.

[0070] In the first embodiment, when the air bag 30 is attached to the seat back 12, the first air chamber 51 is located lower than the second air chamber 52. In a modified example, when the air bag 30 is attached to the seat back 12, the first air chamber 51 may be located higher than the second air chamber 52. The same applies to the second embodiment.

[0071] In the first embodiment, the air bag 30 may be attached to the outer surface of the cover of the seat back 12. In this case, the air bag 30 comes into contact with the user's lower back without being sandwiched between the cover of the seat back 12.

[0072] In air pressure system 20, pump 21 may be a manual pump. That is, a user may manually supply air to at least one of first air chamber 51 and second air chamber 52 of air bladder 30. In this case, air pressure system 20 preferably includes an exhaust valve for manually discharging air from first air chamber 51 and second air chamber 52.

[0073] <Summary of the above embodiment> The air bag is provided on the seat back of the seat and supports the lower back of a user seated on the seat, and comprises two films, a first air chamber and a second air chamber individually provided between the two films, the first air chamber and the second air chamber expanding when air is supplied and contracting when air is exhausted, a first joint that joins the two films to define the first air chamber, and a second joint that joins the two films to define the second air chamber.

[0074] In the air bag, the first and second air chambers are formed by joining two films at a first joining section and a second joining section. In other words, the air bag has two air chambers. Therefore, when attaching an air bag with the above configuration to a seat, the work required for attachment is more efficient than when attaching two air bags with one air chamber to a seat back.

[0075] In the above air bag, it is preferable that the first air chamber and the second air chamber are arranged adjacent to each other, and that the first joint and the second joint include a common joint at the boundary between the first air chamber and the second air chamber that separates both the first air chamber and the second air chamber.

[0076] The air bag has a common joint that separates both the first air chamber and the second air chamber, which allows the air bag to have a small joint area between the two films. In the above air bag, when viewed from the thickness direction of the two films, it is preferable that the common joint is curved so that the first air chamber is convex relative to the second air chamber in the adjacent direction in which the first air chamber and the second air chamber are adjacent.

[0077] The air bladders are mounted on the seat so that their adjacent directions are aligned with the height of the seat back. Consider a comparative example of an air bladder in which the common joint extends linearly in the width direction of the seat back. This comparative example of an air bladder has a portion that cannot inflate in the vertical direction. In other words, because the common joint of the comparative example of an air bladder is constant in the vertical and width directions, the portion of the air bladder that inflates may vary slightly as the air bladder repeatedly inflates. As a result, there is a portion that cannot support the user's lower back in the vertical direction. In contrast, in the air bladders configured as described above, the common joint is curved so that the first air chamber is convex toward the second air chamber. This inevitably results in a difference between the portion that inflates more and the portion that inflates less, particularly in the second air chamber of the air bladder. As a result, the air bladders have fewer portions that cannot support the user's lower back in the vertical direction. Therefore, the air bladders can support the user's lower back in the manner desired by the user.

[0078] In the above air bag, when the direction perpendicular to the adjacent direction is defined as the width direction, it is preferable that the common joint is curved in the adjacent direction so that the center of the first air chamber in the width direction is convex with respect to the center of the second air chamber in the width direction.

[0079] The common joint of the air bladders is curved so that the central portion in the width direction of the first air chamber is convex toward the second air chamber, allowing the air pressure system to inflate and deflate the first air chamber and the second air chamber symmetrically in the width direction.

[0080] The air bag is provided with a first connection port through which air supplied to the first air chamber and air discharged from the first air chamber pass, and a second connection port through which air supplied to the second air chamber and air discharged from the second air chamber pass, and when the first joint and the second joint are viewed in the thickness direction of the two films, it is preferable that both the first joint and the second joint have a linear extending portion and a curved extending portion, and that the first connection port is provided in the curved extending portion of the first joint, and that the second connection port is provided in the curved extending portion of the second joint.

[0081] Because the first connection port is provided in a curved portion of the first joint, stress is less likely to concentrate around the first connection port even when the first air chamber expands. Similarly, because the second connection port is provided in a curved portion of the second joint, stress is less likely to concentrate around the second connection port even when the second air chamber expands. This allows the air bag to have increased durability around the first and second connection ports. [Explanation of symbols]

[0082] 30, 30A...air bag, 31, 32...film, 41, 61...first joint, 42, 62...second joint, 43, 63...common joint, 51, 71...first air chamber, 52, 72...second air chamber, 53, 73...first connection port, 54, 74...second connection port

Claims

1. An air bag provided in a seat back of a seat to support a lumbar region of a user seated in the seat, Two films and a first air chamber and a second air chamber that are individually provided between the two films, the first air chamber and the second air chamber expanding when air is supplied and contracting when air is exhausted; a first joining portion joining the two films together so as to define the first air chamber; a second joining portion that joins the two films together so as to define the second air chamber; Air bag.

2. The first air chamber and the second air chamber are provided adjacent to each other, The first joint portion and the second joint portion include a common joint portion that partitions both the first air chamber and the second air chamber at a boundary between the first air chamber and the second air chamber. The air bag of claim 1 .

3. When viewed from the thickness direction of the two films, The common joint is curved so that the first air chamber is convex with respect to the second air chamber in an adjacent direction in which the first air chamber and the second air chamber are adjacent to each other. The air bag of claim 2.

4. When the direction perpendicular to the adjacent direction is defined as the width direction, The common joint is curved in the adjoining direction so that a central portion of the first air chamber in the width direction is convex with respect to a central portion of the second air chamber in the width direction. The air bag of claim 3.

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