The present invention relates to an applicator that includes a cylindrical syringe including a cartridge fitting portion provided at one of two ends of the cylindrical syringe and configured to be fitted with a cartridge, and a plunger configured to be inserted into the cylindrical syringe and to press a piston inside the cartridge.
An example applicator 200, which includes a cylindrical syringe and a plunger, is disclosed in
Another example applicator, which includes a cylindrical syringe 526 and a plunger 26, is disclosed in
Judging from the respective configurations of the applicators disclosed in JP 2003-79642 A and JP 2001-112782 A, it is considered that the cylindrical syringe is made of metal and that the plunger is made of metal although not clearly stated in the documents. The applicators made of metal advantageously have a high mechanical strength and can be repeatedly used, but are too expensive to be disposable. If the applicators are so expensive, expanded sales of the cartridges may be adversely affected.
An object of the present invention is to provide an applicator that is molded from a resin material and that is inexpensive compared to those according to the related art.
Another object of the present invention is to provide an applicator in which a plunger does not easily slip out of a cylindrical syringe.
An applicator according to the present invention includes a cylindrical syringe molded from a resin material and a plunger molded from a rein. The cylindrical syringe has two ends, and includes a cartridge fitting portion at one of the two ends of the cylindrical syringe. The cartridge fitting portion is configured to be fitted with a cartridge which includes a cylindrical portion having two ends and an opening portion formed at one of the two ends of the cylindrical portion, a nozzle portion provided at the other of the two ends of the cylindrical portion, and a piston disposed inside the cylindrical portion to push out a content contained in the cylindrical portion from the nozzle portion. The plunger has two ends and includes a pressing portion provided at one of the two ends of the plunger and configured to be inserted into the cylindrical syringe from the other of the two ends of the cylindrical syringe and to press the piston inside the cartridge fitted with the cartridge fitting portion, and an operated portion provided at the other of the two ends of the plunger, extending through the other end of the cylindrical syringe, and configured to be pressed by a finger of an operator. Thus, the price of the applicator can be significantly reduced compared to that according to the related art. In the present invention, a resistance structure is provided between an inner peripheral surface of the cylindrical syringe and an outer peripheral surface of the pressing portion of the plunger. The resistance structure is configured to act as resistance to movement of the pressing portion when the pressing portion is moved toward the cartridge fitting portion beyond a predetermined position and to movement of the pressing portion when the pressing portion is moved from the side of the cartridge fitting portion toward the other end of the cylindrical syringe beyond the predetermined position. The resistance structure is configured to allow the pressing portion to be moved beyond the predetermined position against the resistance when a force equal to or greater than a predetermined force is applied to the plunger in a longitudinal direction of the plunger. It is difficult to provide resin molded products with a high precision compared to metallic parts because of expansion and contraction of a resin. Further, the plunger inserted into the cylindrical syringe may easily slip out of the cylindrical syringe. For these reasons, without the resistance structure described above, the plunger may slip out of the cylindrical syringe when a user uses the applicator with the plunger being directed downward and releases his/her finger from the operated portion of the plunger. Therefore, when an applicator without the resistance structure is used, it is necessary for the user to always support the operated portion of the plunger with his/her finger so that the plunger does not slip off by itself. In the present invention, the resistance structure is provided between the inner peripheral surface of the cylindrical syringe and the outer peripheral surface of the pressing portion of the plunger. Thus, even though the cylindrical syringe and the plunger are molded from a resin material, the plunger does not easily slip out of the cylindrical syringe unless a force equal to or greater than a predetermined force is applied to the plunger in the longitudinal direction of the plunger. Thus, according to the present invention, it is possible to provide a practically trouble-free applicator at a low price even if the cylindrical syringe and the plunger are molded from a resin material. This allows the applicator to be disposable.
The resistance structure may be located at any position between the cartridge fitting portion of the cylindrical syringe and the other end of the cylindrical syringe.
The resistance structure may include at least one outer projecting portion integrally formed with the inner peripheral surface of the cylindrical syringe to project radially inward, and at least one inner projecting portion integrally formed with the outer peripheral surface of the pressing portion of the plunger to project radially outward. In this configuration, the resin material for forming the cylindrical syringe and a shape of the at least one outer projecting portion and the resin material for forming the plunger and a shape of the at least one inner projecting portion may be determined such that the at least one inner projecting portion and the at least one outer projecting portion are deformed to allow the at least one inner projecting portion to pass over the at least one outer projecting portion when a force equal to or greater than the predetermined force is applied to the plunger. With this configuration, the at least one inner projecting portion and the at least one outer projecting portion, which are components required for the resistance structure, can be integrally formed with the cylindrical syringe and the plunger, respectively, when the cylindrical syringe and the plunger are molded.
Preferably, the resin material for forming the cylindrical syringe and the resin material for forming the plunger are polypropylene. Polypropylene is available at a low unit price, has a high chemical resistance, has high strength and elasticity compared to polyethylene, and therefore is suitably used to mold the cylindrical syringe and the plunger.
The at least one inner projecting portion may be constituted from one annular projecting portion that continuously annularly extends on the outer peripheral surface of the pressing portion of the plunger, and a cross-sectional shape of the annular projecting portion may have a profile of which the height gradually increases continuously toward an apex of the profile, as the annular projecting portion is cut in a direction orthogonal to a circumferential direction of the plunger. In this case, preferably, the at least one outer projecting portion is constituted from a plurality of distributed projecting portions provided at predetermined angular intervals in a circumferential direction of the cylindrical syringe. A cross-sectional shape of each distributed projecting portion has a profile of which the height gradually increases continuously toward an apex of the profile, as the distributed projecting portions are cut in a direction orthogonal to the circumferential direction of the cylindrical syringe and a cross-sectional shape of each distributed projecting portion has a profile of which the height gradually increases continuously toward an apex of the profile, as the distributed projecting portions are cut in the circumferential direction of the cylindrical syringe.
Conversely, the at least one outer projecting portion may be constituted from one annular projecting portion that continuously annularly extends on the inner peripheral surface of the cylindrical syringe, and a cross-sectional shape of the annular projecting portion may have a profile of which the height gradually increases continuously toward an apex of the profile, as the annular projecting portion is cut in a direction orthogonal to a circumferential direction of the cylindrical syringe. In this case, preferably, the at least one inner projecting portion is constituted from a plurality of distributed projecting portions provided at predetermined angular intervals in a circumferential direction of the plunger. A cross-sectional shape of each distributed projecting portion has a profile of which the height gradually increases continuously toward an apex of the profile, as the distributed projecting portions are cut in the direction orthogonal to the circumferential direction of the plunger, and a cross-sectional shape of each distributed projecting portion has a profile of which the height gradually increases continuously toward an apex of the profile, as the distributed projecting portions are cut in the circumferential direction of the plunger.
In such configuration as the resistance structure is constituted from the annular projecting portion and the plurality of distributed projecting portions, the annular projecting portion and the plurality of distributed projecting portions can be easily deformed when a force equal to or greater than a predetermined force is applied to the plunger in the longitudinal direction of the plunger when either one of the annular projecting portion and the plurality of distributed projecting portions passes over the other. In contrast, after either one of the annular projecting portion and the plurality of distributed projecting portions has passed over the other, either one of the annular projecting portion and the plurality of distributed projecting portions will not pass over the other in the opposite direction even if the plunger is rotated in the cylindrical syringe unless a predetermined force is applied to the plunger in the longitudinal direction of the plunger. Thus, the plunger can be prevented from slipping off with a simple structure.
Preferably, the profile of each distributed projecting portion has a flat portion provided at the apex of the profile, and a skirt formed on the side of the cartridge fitting portion with respect to the flat portion is longer than a skirt formed on the side of the other end of the cylindrical syringe with respect to the flat portion. In such configuration as the distributed projecting portions include the flat portion, the apexes of the distributed projecting portions are more uniformly worn when either one of the annular projecting portion and the plurality of distributed projecting portions passes over the other. This prevents the apexes of the distributed projecting portions from being worn out early even if an action of either one of the annular projecting portion and the plurality of distributed projecting portions passing over the other or a converse action is repeatedly performed a certain number of times. As a result, the applicator can be used a plurality of times even if the cylindrical syringe and the plunger are molded from a resin material. In such configuration as the profile of each distributed projecting portion has the flat portion, production thereof can more accurately be managed.
The predetermined angular intervals between the plurality of distributed projecting portions are arbitrary, but are preferably 60°, 90°, or 120°. With such an angle, both high molding precision and high strength can be easily achieved even if the cylindrical syringe and the plunger are molded from a resin material.
The resistance structure may be disposed at an arbitrary position. Preferably, however, the resistance structure is provided adjacent to the cartridge fitting portion of the cylindrical syringe. With this positional arrangement, the distance by which the plunger is moved downward by itself from the cylindrical syringe when the operator holds the applicator with the plunger being directed downward can be reduced, thereby improving the operability of the applicator.
Preferably, a stopper portion is provided in the vicinity of the operated portion of the plunger to abut on the other end of the cylindrical syringe. With such stopper portion, it is possible to prevent the operator from pushing the plunger too far into the cylindrical syringe to cause the pressing portion located at the leading end of the plunger molded from a resin material to apply a strong force to the cartridge fitted with the cartridge fitting portion and thereby to break the cartridge and the cartridge fitting portion.
Preferably, the plunger is shaped such that the outer peripheral surface of a portion that is adjacent to the stopper portion is proximate to the inner peripheral surface of the cylindrical syringe. With such structure, the plunger can be stably moved along the cylindrical syringe at the final stage of pushing in the plunger. As a result, the operability of the applicator is improved. In the state in which the plunger has been pushed in, the plunger can be suppressed from moving in the direction of slipping out of the cylindrical syringe, thereby facilitating handling of the applicator.
Preferably, the resistance structure is positioned such that the cartridge can be fitted with the cartridge fitting portion and the cartridge can be removed from the cartridge fitting portion when the at least one inner projecting portion of the plunger is in contact with the at least one outer projecting portion. With this configuration, the cartridge can be mounted and removed without removing the plunger.
Now, with reference to the accompanying drawings, an embodiment of the present invention will be described below in detail, wherein the present invention is applied to an applicator used for discharging a paste-type dental material.
The applicator 1 includes the cylindrical syringe 5 and the plunger 7. As illustrated in
In the present embodiment, a stopper portion 76 that abuts on the other end 53 of the cylindrical syringe 5 is provided in the vicinity of the operated portion 74 of the plunger 7. Providing such stopper portion 76 in this way prevents the operator from pushing the plunger 7 too far into the cylindrical syringe 5 to break the plunger 7 or the cylindrical syringe 5 which is made of a resin material. The plunger 7 is shaped such that the outer peripheral surface of a portion 77 that is adjacent to the stopper portion 76 is proximate to the inner peripheral surface of the cylindrical syringe 5. With adoption of such structure, the plunger 7 can be stably moved along the cylindrical syringe 5 when the plunger 7 is pushed in. As a result, the plunger 7 is not swung when the plunger 7 is pushed in, thereby improving the operability of the applicator 1. In addition, the plunger 7 advantageously does not easily slip out of the cylindrical syringe 5.
In the present embodiment, as illustrated in
In the embodiment, as illustrated enlargedly in
As illustrated in
As illustrated enlargedly in
In contrast, the resistance structure according to the embodiment described above, the at least one outer projecting portion 54 maybe constituted from one annular projecting portion that continuously annularly extends on the inner peripheral surface of the cylindrical syringe 5, and the cross-sectional shape of the annular projecting portion may have a mountain-like profile of which the height gradually increases continuously toward the apex of the profile, as the annular projecting portion is cut in a direction orthogonal to the circumferential direction of the cylindrical syringe 5. In this configuration, the at least one inner projecting portion 75 may be constituted from a plurality of distributed projecting portions provided at predetermined angular intervals in the circumferential direction of the plunger 7, and the cross-sectional shape of each distributed projecting portion may have a profile of which the height gradually increases continuously toward the apex of the profile, as the distributed projecting portions are cut in the direction orthogonal to the circumferential direction of the plunger 7 and the cross-sectional shape of each distributed projecting portion may have a profile of which the height gradually increases continuously toward the apex of the profile, as the distributed projecting portions are cut in the circumferential direction of the plunger 7.
In a configuration as in the present embodiment, wherein the resistance structure (54, 75) is constituted from the one annular projecting portion 75′ and the plurality of distributed projecting portions 54′, the annular projecting portion 75′ and the plurality of distributed projecting portions 54′ can be easily deformed when a force equal to or greater than a predetermined force is applied to the plunger 7 in the longitudinal direction of the plunger 7 as either one of the annular projecting portion 75′ and the plurality of distributed projecting portions 54′ passes over the other. In contrast, after either one of the annular projecting portion 75′ and the plurality of distributed projecting portions 54′ has passed over the other, either one of the annular projecting portion 75′ and the plurality of distributed projecting portions 54′ does not pass over the other in the opposite direction, even if the plunger 7 is rotated in the cylindrical syringe 5, unless a predetermined force is applied to the plunger 7 in the longitudinal direction of the plunger 7. Thus, the plunger 7 can be prevented from slipping off with a simple structure.
The position P of the resistance structure (54, 75) may be determined as desired. Preferably however, the resistance structure is provided adjacent to the cartridge fitting portion 52 of the cylindrical syringe 5 as in the present embodiment. If the resistance structure is located at the position P, it is possible to reduce the distance by which the plunger 7 is moved downward from the cylindrical syringe 5 when the operator holds the applicator 1 with the plunger 7 being directed downward, thereby improving the operability of the applicator 1. In practice, the resistance structure (54, 75) is preferably positioned such that the cartridge 3 can be fitted with the cartridge fitting portion 52 and the cartridge 3 can be removed from the cartridge fitting portion 52 when the at least one inner projecting portion 75 of the plunger 7 is in contact with the at least one outer projecting portion 54. With this configuration, the cartridge 3 can be mounted and removed without removing the plunger 7.
As illustrated in
The through hole 38 is shaped such that the radial dimension of the through hole 38, which extends in the longitudinal direction of the nozzle portion 35 continuously with the tapered surface 38A, becomes gradually smaller and thereafter constant. With this configuration, the pipe 36 can be easily inserted to the middle of the through hole 38, after which the pipe 36 is press-fitted, thereby alleviating the workload of press-fitting.
The piston 4 is integrally molded from a resin material such as polypropylene. As illustrated in
As illustrated in
As illustrated in
A stepped portion 52E to be engaged with the flange portion 39 is formed between the flange fitting recess 52C1 and the cylindrical portion fitting recess 52C2. The stepped portion 52E is configured to entirely contact the end surface of the flange portion 39 located on the side of the cylindrical portion 33. With adoption of this structure, the flange portion 39 is pressed against the stepped portion 52E when the piston 4 is pushed by the plunger 7, thereby preventing the cartridge 3 from popping out of the cartridge fitting portion 52.
When mounting the cartridge 3, as illustrated in
While the preferred embodiments of the present invention have been described and shown herein, the present invention should not be construed in a limiting sense. It should be understood that various modifications, rearrangements, and substitutions may be made without departing from the scope of the present invention.
In a configuration according to the present invention wherein the resistance structure is provided between the inner peripheral surface of the cylindrical syringe and the outer peripheral surface of the pressing portion of the plunger, the plunger will not readily slip off from the cylindrical syringe, even if the cylindrical syringe and the plunger are each molded from a resin material, unless a force equal to or greater than a predetermined force is applied to the plunger in the longitudinal direction of the plunger. According to the present invention, therefore, a practically trouble-free applicator can be provided at low cost even though the cylindrical syringe and the plunger are molded from a resin material, thereby enabling the applicator to be disposable.
Number | Date | Country | Kind |
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2015-140832 | Jul 2015 | JP | national |