Sealant charging process in sealant-incorporated tire tube

Abstract: In a sealant-incorporated tire including a loop-shaped sealant chamber f illed with a sealant 5 and defined between a tire body 1 and an inner liner 8 by superposing and adhering the inner liner 8 onto an inner surface of the tire body 1, a sealant charging bore 8a is formed in the inner liner 8, and the sealant 7 is charged into the sealant chamber 6 through the sealantchargingbore8a. Then,airpresentinthe sealantchamber 6 is discharged by evacuation and thereafter, a crude rubber sheet 74 is adhered in a state in which the periphery of the sealant charging bore 8a has been clamped, thereby closing the sealant charging bore 8a. Thus, it is possible to charge the sealant 7 in a short time, and also to prevent heat generated during vulcanization and formation of the tire from being applied to the sealant 7, thereby preventing the deterioration of the sealant 5.

Description: FIELD OF THE INVENTION The present invention relates to a sealant-incorporated tire tube provided therein with an air chamber filled with air and a sealant chamber filled with a sealant, and particularly, to a process of charging the sealant into the sealant chamber. BACKGROUND ART There are sealant-incorporated tires known from Japanese Patent Application Laid-open Nos.4-5029 and 8-323875, in which a sealant chamber is defined inside a tread of a tire body and filled with a sealant, so that the puncture of the tread by a nail or the like is sealed by the sealant encapsulated in the sealant chamber to retard the leakage of air through the puncture. It should be noted here that in the sealant-incorporated tire described in Japanese Patent Application Laid-open No.4-5029, the sealant is encapsulated in the sealant chamber at a state of forming a crude tire and for this reason, there is a possibility that the sealant might be deteriorated by heat produced during vulcanization and formation of the tire, resulting ina reduced sealing effect. The sealant-incorporated tire described in Japanese Patent Application Laid-open No.8-323875 suffers from the following problems: The sealant is charged by a syringe into the sealant chamber in the vulcanized and molded tire and hence, there is not a possibility that the sealant might be deteriorated by heat, but air remains in the sealant chamber, and it takes a long time for charging the sealant. There are also sealant-incorporated tire tubes known from Japanese Patent Application Laid-open Nos. 58-74342 and 9-300481, in which a sealant is charged into the tire tube, so that the puncture of the tire tube by a nail or the like is sealed by the sealant to retard the leakage of air. In the tire tube described in Japanese Patent Application Laid-open No. 58-74342, a sealant-incorporated capsule is inserted into the tire tube before being vulcanized and molded, so that the capsule is broken by an external force after vulcanization and molding of the tire tube to disperse the sealant within the tire tube. In the tire tube described in Japanese Patent Application Laid-open No.9-300481, the sealant is charged into the sealant chamber through a sealant charging bore made in the tire tube in a state in which air has been charged into the air chamber in the tire tube to force the air out of sealant chamber. In the former sealant charging process, however, there is a possibility that the tire tube might be damaged, when the external force is applied to break the capsule, and moreover, there is a possibility that the sealant might clog a pneumatic valve mounted in the tire tube. The latter sealant charging process suffers from a problem that it is difficult to completely discharge the air present in the sealant chamber, and also it takes a long time for discharging the air out of the sealant chamber. EP-A-0816133 and WO-A-9808670 each disclose a process for charging a sealant-incorporated tire in which air is supplied to an air chamber of the tire to expel air from a sealant chamber before sealant is supplied to the sealant chamber. EP-A-0329454 discloses a tire which includes in its structure a layer of a sealing material which has a viscosity at room temperature such that the material can be handled as a sheet. Consequently, the sealing material can be treated, in the tire manufacturing process, in the same manner as other components of the tire. DISCLOSURE OF THE INVENTION The present invention has been accomplished with the above circumstances in view, and it is an object of the present invention to ensure that an operation for charging a sealant into a sealant chamber in a tire tube is completed in a short time, while avoiding the incorporation of air, and the charged sealant is reliably prevented from being leaked through a sealant charging bore. According to the present invention, there is proposed a sealant charging process in a sealant-incorporated tire tube provided therein with an air chamber filled with air and a sealant chamber filled with a sealant, characterized in that the process comprises a first step of forming a sealant charging bore in an outer peripheral wall of the tire tube to communicate with the sealant chamber, a second step of inserting a sealant injecting hose into the sealant chamber through the sealant charging bore and supplying air into the air chamber through a pneumatic valve mounted in the tire tube, a third step of charging the sealant into the sealant chamber through the sealant injecting hose, while discharging the air present in the air chamber through the pneumatic valve, a fourth step of buffing the periphery of the sealant charging bore in a state in which the periphery has been clamped, and a fifth step of closing the sealant charging bore in a state in which the periphery of the sealant charging bore has been clamped. With the above feature, after the air is supplied into the air chamber through the pneumatic valve to force the air out of the sealant chamber, the sealant is charged into the sealant chamber. Therefore, the sealant can be charged in a short time without incorporation of the air in the sealant. Particularly, the air in the air chamber is discharged when the sealant is charged into the sealant chamber, and hence, the sealant can be supplied easily without application of a strong pressure. In addition, the sealant charging bore may be closed by a thermosetting resin or the hot-melt resin in the state in which the periphery thereof has been clamped and hence, the sealant charging bore can be closed in an extremely short time, while preventing the air from entering again into the sealant chamber through the sealant charging bore. Moreover, the periphery of the sealant charging bore is buffed in its clamped state and hence, it is possible to prevent the tire tube from being damaged by a buffing load, and also to remove oil and a stain to enhance the closing strength of the bore. Thefifth step may comprise depositing the thermosetting resin to the periphery of the sealant charging bore and then heating and pressing the thermosetting resin to close the sealant charging bore. With the above feature, the thermosetting resin is deposited to the periphery of the sealant charging bore and then heated and pressed to close the sealant charging bore. Therefore, the thermosetting resin is smoothly integrated with the tire tube, leading to an enhanced appearance. The sealant charging bore may be closed by a crude rubber sheet in the state in which the periphery of the sealant charging bore has been clamped. Therefore, the sealant charging bore can be closed in an extremely short time, while preventing the air from entering again into the sealant chamber through the sealant charging bore. The fifth step may comprise a stage of clamping the periphery of the sealant charging bore, while discharging the air present in the sealant chamber by evacuation, a stage of buffing the periphery of the sealant charging bore in a state in which the periphery has been clamped, and a stage of closing the sealant charging bore by adhesion of a crude rubber sheet. With the above feature, the crude rubber sheet is adhered in the state in which the periphery of the sealant charging bore has been clamped and hence, it is possible to prevent the displacement of a position of adhesion of the crude rubber sheet to ensure a quality of an adhesive joint, while preventing the air from entering again into the sealant chamber through the sealant charging bore in the course of adhering. Moreover, the periphery of the sealant charging bore is buffed in its clamped state and hence, it is possible to prevent the tire tube from being damaged by a buffing load, and also to remove oil and a stain to enhance the adhesive strength of the crude rubber sheet. The first step of forming the sealant charging bore in the outer peripheral wall of the tire tube may be carried out in a process of producing the tire tube. With the above feature, the sealant charging bore is formed in the outer peripheral wall of the tire tube in the tire tube producing process and hence, the number of steps for forming the sealant charging bore is reduced. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 to 3G show a first embodiment of the present invention. Fig. 1 is a cross-sectional view of a wheel provided with a tube-incorporated tire; Fig. 2 is a sectional view taken along a line 2-2 in Fig.1; and Figs. 3A to 3G are views for explaining a sealant charging process. Figs. 4H to 4J are views for explaining a sealant charging process according to a second embodiment of the present invention. Figs. 5K to 5M are views for explaining a sealant charging process according to a third embodiment of the present invention. Figs. 6A to 6H are views for explaining a sealant charging process according to a fourth embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION As shown in Figs. 1 and 2, a tube-incorporated tire T comprising a tire body 1 and a tire tube 2 accommodated in the tire body 1 is mounted on a rim R of a wheel of a motorcycle. The tire tube 2 includes a peripheral wall 3, which is formed into an annular shape in section and which includes an air chamber peripheral wall portion 3i located at a radially inner side of the tire T, and a sealant chamber peripheral wall portion 3o located at a radially outer side of the tire T. Connections of the air chamber peripheral wall portion 3i and the sealant chamber peripheral wall portion 3o in the peripheral wall 3 are connected to each other by a partition wall 4 formed integrally with them. Air is charged into an air chamber 5 which is substantially circular in section and which is defined between the air chamber peripheral wall portion 3i and the partition wall 4, and a gelled sealant 7 is charged into a sealant chamber 6 which is substantially arcuate in section and which is defined between the sealant chamber peripheral wall portion 3o and the partition wall 4. The rim R includes an annular rim body 11 extending in a circumferential direction of the tire T, and a pair of flange portions 12, 12 extending radially outwards from widthwise opposite ends of the rim body 11 to retain an inner periphery of the tire body 1. A pneumatic valve 13 for charging air into an air chamber 5 defined in the tire tube 2 is supported through a pneumatic valve-mounting portion 14 formed at a circumferentially one point on the rim body 11. The sealant chamber 6 in the tire tube 2 is maintained in a shape extending along the inner side of the tread 15 by an air pressure in the air chamber 5. Therefore, even if the tire tube 2 is punctured radially or sideways by a nail or the like, the sealant 7 fills the puncture immediately to repair the puncture, thereby retarding the leakage of the air from the air chamber 5. The sealant 7 is retained in the sealant chamber 6 and cannot issue out into the air chamber 5 and hence, the pneumatic valve 13, a pressure gauge applied to the pneumatic valve 13 or the like cannot be clogged. A step of charging the sealant 7 into the sealant chamber 6 in the tire tube 2 will be described with reference to Figs . 3A and 3G. First, the tire tube 2, into which the sealant 7 is still not charged, is placed so that its inner peripheral surface (the air chamber peripheral wall portion 3i) is supported on an upper surface of a support plate 121 disposed horizontally. Then, a hot nail 122 heated to about 400°C by an electric heater is dropped toward the support plate 121 from the above to make a sealant charging bore 2a in an outer peripheral surface (the sealant chamber peripheral wall portion 3o) of the tire tube 2. By using the hot nail 122 heated in the above manner, the sealant charging bore 2a can be simply and reliably formed in the tire tube 2 made of a rubber (see Fig. 3A). After the hot nail 122 is retracted upwards, a sealant injecting hose 123 is inserted through the sealant charging bore 2a into the sealant chamber 6, until it reaches the bottom of the sealant chamber 6. In the process illustrated in Figures 3B to 3D, which is not in accordance with the present invention, the sealant 7 is injected through the sealant injecting hose 123 via the sealant charging bore 2a into the bottom of the sealant chamber 6 . When the sealant injecting hose 123 is withdrawn, the sealant 7 stays on the bottom of the sealant chamber 6 by gravitation, and the air remains in the upper portion of the sealant chamber 6 (see Fig. 3B). Then, a vacuum pad 124 connected to a vacuum source (not shown) is lowered and attracted to the periphery of the sealant charging bore 2a to suck the air remaining in the sealant chamber 6 (see Fig.3C). In a process in accordance with the present invention, after the sealant injecting hose 123 is inserted into the sealant chamber 6 through the sealant charging bore 2a, air is supplied into the air chamber 5 in the tire tube 2, and the sealant 7 is then charged into the sealant chamber 6 through the sealant injecting hose 123, while discharging the air from the air chamber 5. Subsequently, an annular clamp member 125 is lowered, so that its lower surface is pressed against the tire tube 2 to surround the periphery of the sealant charging bore 2a, whereby the air chamber peripheral wall portion 3i, the partition wall 4 and the sealant chamber peripheral wall portion 3o of the tire tube 2 are clamped trebly between the clamp member 125 and the support plate 121 (see Fig.3D). At this time, the partition wall 4 and the sealant chamber peripheral wall portion 3o, excluding the section with sealant 7 charged thereto, are brought into close contact with each other, because the air in the sealant chamber 6 has been discharged by the admission of air into the air chamber 5. There is not a possibility that the air might enter through the sealant charging bore 2a into the sealant chamber 6, because the clamp member 125 is clamping the periphery of the sealant charging bore 2a so as to surround it. Then, the periphery of the sealant charging bore 2a surrounded by the clamp member 125 is abraded by a buff 126, while maintaining the clamping by the clamp member 125, thereby removing oil and a stain deposited on the periphery of the sealant charging bore 2a (see Fig.3E). At this time, a load is applied to the periphery of the sealant charging bore 2a by the buff 126 which is being rotated, but it is possible to reliably prevent the tire tube 2 from being deformed and damaged by a frictional force received from the buff 126, because such periphery is non-movably clamped by the clamp member 125. Subsequently, a crude rubber sheet 128 is put into abutment against the periphery of the sealant charging bore 2a and heated by a crude rubber sheet adhering device 127, whereby it is vulcanized and adhered to close the sealant charging bore 2a (see Fig.3F). In this manner, the crude rubber sheet 128 is vulcanized and adhered with the periphery of the sealant charging bore 2a clamped so as to be surrounded by the clamp member 125 and hence, it is possible to reliably prevent the adhered position from being displaced to ensure the adhesive quality. In addition, the crude rubber sheet 128 is vulcanized and adhered after abrasion of the periphery of the sealant charging bore 2a by the buff 126 and hence, it is possible to avoid a reduction in adhesive strength due to a strain of an adhesive surface. Then, the crude rubber sheet adhering device 127 and the clamp member 125 are retracted upwards to complete the tire tube 2 (see Fig.3G). In the tire tube 2 immediately after being completed, the sealant 7 stays on the bottom of the sealant chamber 6, but when the tire tube 2 is mounted to the tire body 1 and actually allowed to travel, the sealant 7 is diffused uniformly within the sealant chamber 6 by the action of centrifugal force. A process of charging a sealant 7 according to a second embodiment of the present invention will be described below with reference to Figs. 4H to 4J. In the process of charging the sealant 7 according to the second embodiment, the first step to the abrading step using a buff 126 are the same as those in the first embodiment (see Figs. 3A to 3F), but the step of closing the sealant charging bore 2a is different from that in the fifth embodiment. More specifically, an acrylic or urethane-based thermosetting resin 130 is supplied as a sealer from a sealer supply nozzle 129 to the periphery of the sealant charging bore 2a abraded by the buff 126 (see Fig. 4H). After the sealer supply nozzle 129 is retracted upwards, the thermosetting resin 130 is then heated for 15 to 30 seconds and formed into a predetermined shape by a forming die 131 heated to approximately 180° (see Fig. 4I). When the thermosetting resin 130 is cooled and cured, the sealant charging bore 2a is closed, and in this manner, a tire tube 2 is completed (see Fig. 4J). During the step of closing the sealant charging bore 2a, the clamp member 125 is clamping the periphery of the sealant charging bore 2a to surround it. A process of charging the sealant 7 according to a third embodiment of the present invention will be described below with reference to Figs. 5K and 5M. In the process of charging the sealant 7 according to the third embodiment, the first step to the abrading step using the buff 126 are the same as those in the first embodiment (see Figs. 3A to 3E), but the step of closing the sealant charging bore 2a is different from that in the first embodiment, as is in the second embodiment. More specifically, a forming die 132 is put into abutment against the periphery of the sealant charging bore 2a abraded by the buff 126, and a molten hot-melt resin 133 is injected through the inside of the forming die 132 (see Fig.5K). Subsequently, cooling water is allowed to flow through the inside of the forming die 132 to cool and solidify the hot-melt resin 133 (see Fig. 5L), thereby closing the sealant charging bore 2a by the solidified hot-melt resin 133 to complete the tire tube 2 (Fig. 5M). During the step of closing the sealant charging bore 2a, the clamp member 125 is clamping the periphery of the sealant charging bore 2a so as to surround it. As described above, according to each of the second and third embodiments, the sealant charging bore 2a is closed by the thermosetting resin 130 or the hot-melt resin 133 in a state in which the periphery of the sealant charging bore 2a has been clamped by the clamp member 125. Therefore, it is possible to prevent air from entering again through the sealant charging bore 2a into the sealant chamber 6 which once depleted air and moreover, it is possible to close the sealant charging bore 2a in a short time, as compared with a case where the crude rubber sheet 128 is adhered to the sealant charging bore 8a. In addition, it is possible to enhance the closing strength provided by the thermosetting resin 130 or the hot-melt resin 133 by previously buffing the periphery of the sealant charging bore 2a. Next, a process of charging a sealant 7 according to a fourth embodiment of the present invention will be described below with reference to Figs. 6A to 6H. First, a tire tube 2, into which a sealant 7 is still not charged, is placed so that its inner surface (its air chamber peripheral wall portion 3i) is supported on an upper surface of a support plate 221 disposed horizontally. A hot nail 222 heated to about 400°C by an electric heater is dropped toward a support plate 221 from the above to make a sealant charging bore 2a in an outer peripheral surface (the sealant chamber peripheral wall portion 3o) of the tire tube 2. By using the hot nail 222 heated in the above manner, the sealant charging bore 2a can be simply and reliably formed in the tire tube 2 made of a rubber (see Fig. 6A). After the hot nail 222 is retracted upwards, a sealant injecting hose 223 is inserted through the sealant charging bore 2a into the sealant chamber 6 toward the bottom thereof, and at the same time, an air nozzle 224 connected to a pressure source such as a compressor is connected to a pneumatic valve 13 to supply air into the air chamber 5 in the tire tube 2 (see Fig. 6B). This causes the air chamber 5 to be expanded, whereby the air within the sealant chamber 6 adjacent the air chamber 5 with the partition wall 4 interposed therebetween is discharged to the outside through the sealant charging bore 2a (see Fig. 6C). Then, the sealant 7 is charged into the bottom of the sealant chamber 6 through a sealant injecting hose 223 , while discharging air within the air chamber 5 through the pneumatic valve 13 and the air nozzle 224 . Since the sealant 7 is charged to the bottom of the sealant chamber 6 through the sealant injecting hose 223, while discharging the air within the air chamber 5 through the pneumatic valve 13 and the air nozzle 224 as described above, the sealant 7 can be easily charged without application of a specially strong pressure, while preventing the air from flowing again into the sealant chamber 6 through the sealant charging bore 2a. Then, the air nozzle 224 is retracted from the pneumatic valve 13 and thereafter, the clamp member 225 is lowered to clamp the periphery of the sealant charging bore 2a by cooperation with the support plate 221, so that air is prevented from entering the sealant chamber 6. Then, theperipheryof the sealant charging bore 2a is abraded by the buff 226 which is being rotated, thereby removing oil and a stain deposited on the periphery of the sealant charging bore 2a (see Fig.6E). At this time, a load is applied to the periphery of the sealant charging bore 2a by the buff 226 which is being rotated, but it is possible to reliably prevent the tire tube 2 from being deformed and damaged by a frictional force received from the buff 226, because such periphery is non-movably clamped by the clamp member 225. Then, an acrylic or urethane-based thermosetting resin 228 is supplied as a sealer from a sealer supply nozzle 227 to the periphery of the sealant charging bore 2a abraded by the buff 226 (see Fig.6F). After the sealer supply nozzle 227 is retracted upwards, the thermosetting resin 228 is then heated for 15 to 30 seconds and formed into a predetermined shape by a forming die 229 heated to approximately 180° (see Fig.30G). When the thermosetting resin 228 is cooled and cured, the sealant charging bore 2a is closed, and in this manner, a tire tube 2 is completed (see Fig. 6H). During the stepof closing the sealant charging bore 2a, the clamp member 225 is clamping the periphery of the sealant charging bore 2a so as to surround it. According to the fourth embodiment, the sealant charging bore 2a is closed by the thermosetting resin 228 in a state in which the periphery of the sealant charging bore 2a is clamped by the clamp member 225, as described above. Therefore, it is possible to prevent air from entering again through the sealant charging bore 2a into the sealant chamber 6 which once depleted air and moreover, it is possible to close the sealant charging bore 2a in a short time, as compared with a case where the crude rubber sheet is adhered to the sealant charging bore 2a. In addition, it is possible to enhance the closing strength provided by the thermosetting resin 228 by previously abrading the periphery of the sealant charging bore 2a by the buff. Further, the thermosetting resin 228 is heated and pressed by the forming die 229 and hence, the thermosetting resin 228 is smoothly integrated with the tire tube 2, leading to an enhanced appearance. As an alternative to the fourth embodiment, the sealant charging bore 2a can be closed by a crude rubber sheet, in place of being closed by the thermosetting resin 228. The closing of the sealant charging bore 2a by the crude rubber sheet can be conducted in the same procedure as that described in the first embodiment with reference to Figs. 3C to 3G. Although the embodiments of the present invention have been described in detail, it will be understood that the present invention is not limited to the above-described embodiments, and various modifications in design may be made without departing from the spirit and scope of the invention defined in the claims. For example, if the sealant charging bore 2a is formed in the outer peripheral wall of the tire tube 2 in the course of producing the tire tube 2 in each of the first to fourth embodiments, the number of producing steps can be reduced. Further, in the fourth embodiment, the sealant charging bore 2a may be closed by bringing the forming die into abutment against the periphery of the sealant charging bore 2a and injecting a molten hot-melt resin through the inside of the forming die, in place of being closed by the thermosetting resin 228. In addition, the step of supplying the air into the air chamber 5 through the pneumatic valve 13 mounted in the tire tube 2 and the step of inserting the sealant injecting hose 223 into the sealant chamber 6 through the sealant charging bore 2a may be conducted simultaneously, or the air may be supplied into the air chamber 5 after insertion of the sealant injecting hose 223. Industrial Applicability As discussed above, the present invention is applicable to a sealant-incorporated tire tube which is provided therein with an air chamber filled with air and a sealant chamber filled with a sealant.

Claims: A sealant charging process in a sealant-incorporated tire tube (2) provided therein with an air chamber (5) filled with air and a sealant chamber (6) filled with a sealant (7), the process comprising a first step of forming a sealant charging bore (2a) in an outer peripheral wall of said tire tube (2) to communicate with said sealant chamber (6), a second step of inserting a sealant injecting hose (223) into said sealant chamber (6) through said sealant charging bore (2a) and supplying air into said air chamber (5) through a pneumatic valve (13) mounted in said tire tube (2), a third step of charging the sealant (7) into said sealant chamber (6) through said sealant injecting hose (223), while discharging the air present in said air chamber (5) through said pneumatic valve (13), a fourth step of buffing the periphery of said sealant charging bore (2a) in a state in which said periphery has been clamped, and a fifth step of closing said sealant charging bore (2a) in a state in which the periphery of said sealant charging bore (2a) has been clamped. A sealant charging process in a sealant-incorporated tiretube (2) as claimed in claim 1, where in the fifth step comprises closing said sealant charging bore (2a) by a thermosetting resin (228) or a hot melt resin. A sealant charging process in a sealant-incorporated tire tube according to claim 1, wherein said fifth step comprises depositing the thermosetting resin (228) to the periphery of said sealant charging bore (2a) and then heating and pressing said thermosetting resin (228) to close said sealant charging bore (2a). A sealant charging process in a sealant-incorporated tire tube (2) as claimed in claim 1, wherein the fifth step comprises closing said sealant charging bore (2a) by adhesion of a crude rubber sheet. A sealant charging process in a sealant-incorporated tire tube according to claim 4, wherein said fifth step comprises clamping the periphery of said sealant charging bore (2a), while discharging the air present in said sealant chamber (6) by evacuation, buffing the periphery of said sealant charging bore (2a) in a state in which said periphery has been clamped, and closing said sealant charging bore (2a) by adhesion of a crude rubber sheet. A sealant charging process in a sealant-incorporated tire tube according to any one of the preceding claims, wherein said first step of forming said sealant charging bore (2a) in the outer peripheral wall of said tire tube (2) is carried out in a process of producing said tire tube (2).

Inventors: HAYASHI TOYOAKI, HAYASHI, TOYOAKI
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 2000
Main classification: B29C73
IPC codes: B29C73, B29D30, B60C5, B60C19