Injector

An injector comprises a cylindrical barrel including a discharge port, a seal body coming into close contact with an inner circumferential surface of the barrel, a plunger for pushing and moving the seal body to the discharge port side of the barrel, and a stopper disposed on one of the barrel and the plunger and coming into elastic contact with the other in a radial direction of the barrel.

TECHNICAL FIELD

The present invention relates to an injector.

BACKGROUND ART

An injector is conventionally known that has a configuration in which a plunger for pushing and moving a seal body toward a discharge port of a barrel is prevented from coming off from the barrel. For example, in the case of the injector described in Patent Document 1, the barrel includes a convex portion projecting from an inner circumferential surface thereof, and the plunger includes a locking portion locked to the convex portion.

PRIOR ART DOCUMENT

Patent Document

Patent Document 1: Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2002-515268

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

However, in the case of the injector described in Patent Document 1, the seal body climbs over the convex portion projecting from the inner circumferential surface of the barrel before being housed into the barrel. In this case, the seal body may be damaged due to contact with the convex portion.

Therefore, a problem to be solved by the present invention is to house a seal body into a barrel without damage and to prevent a plunger from falling off from the barrel in an injector.

Means for Solving Problem

To solve the problem described above, an aspect of the present disclosure provides

an injector comprising:

a cylindrical barrel including a discharge port;

a seal body coming into close contact with an inner circumferential surface of the barrel;

a plunger for pushing and moving the seal body to the discharge port side of the barrel; and

a stopper disposed on one of the barrel and the plunger and corning into elastic contact with the other in a radial direction of the barrel.

Effect of the Invention

According to the present invention, the seal body can be housed into the barrel without damage and the plunger can be prevented from falling off from the barrel in the injector.

MODES FOR CARRYING OUT THE INVENTION

An injector according to an embodiment of the present invention comprises a cylindrical barrel including a discharge port, a seal body coming into close contact with an inner circumferential surface of the barrel, a plunger for pushing and moving the seal body to the discharge port side of the barrel, and a stopper disposed on one of the barrel and the plunger and coming into elastic contact with the other in a radial direction of the barrel.

According to this aspect, the seal body can be housed into the barrel without damage and the plunger can be prevented from falling off from the barrel in the injector.

The stopper may be a plate spring-shaped member including a fixed end attached to the plunger and a free end coming into elastic contact with the inner circumferential surface of the barrel.

In the stopper, the free end may be located on the base end side of the barrel with respect to the fixed end.

In the stopper, the free end may be located on the leading end side of the barrel with respect to the fixed end.

The inner circumferential surface of the barrel may be provided with a circumferential groove with which the free end of the stopper is engaged. Since the free end of the stopper engages with the circumferential groove, the plunger is prevented from coming off from the barrel.

The circumferential groove may have a slope surface extending from a bottom potion of the circumferential groove toward the leading end of the barrel and sloping with respect to the inner circumferential surface. As a result, the plunger can smoothly be housed into the barrel without the free end of the stopper being caught in the circumferential groove.

The stopper and the plunger may be integrated as one part.

The stopper may be a plate spring-shaped member including a fixed end attached to the barrel and a free end coming into elastic contact with the plunger.

The barrel may have two slits formed to extend from a base end thereof, and wherein

the stopper may be made up of a portion of the barrel interposed between the two slits.

The seal body and the plunger may be integrated as one part.

First Embodiment

FIG. 1is an external view of an injector according to a first embodiment of the present invention, andFIG. 2is a partial cross-sectional view of the injector.

As shown inFIGS. 1 and 2, an injector10includes a barrel12containing, for example, a pasty fluid, a movable body14movably housed in the barrel12, and a plunger16for pushing and moving the movable body14. The injector10also has a nozzle tip18attached to a leading end12aof the barrel12and a finger grip20rotatably fitted to a base end12bof the barrel12.

FIG. 3is a cross-sectional view of the barrel, andFIG. 4is an enlarged cross-sectional view of the barrel shown inFIG. 3.

As shown inFIG. 3, the barrel12is a cylindrical member having a central axis C1, and is made of a resin material, for example. The barrel12includes a discharge port12cat the leading end12aand a flange portion12dat the base end12b. By attaching the nozzle tip18to the leading end12aof the barrel12, the discharge port12cis connected to a nozzle inside flow passage communicating with the outside in the nozzle tip18. The flange portion12dfunctions as a stopper preventing the finger grip20rotatably fitted to a base end side portion of the barrel12from falling off.

As shown inFIG. 4, a circumferential groove12fis formed in a base end side portion of an inner circumferential surface12eof the barrel12. The reason why the circumferential groove12fis formed will be described later.

FIG. 5is a perspective view of the movable body, andFIG. 6is a partial cross-sectional view of the movable body.

As shown inFIG. 5, the movable body14is a substantially cylindrical member having a central axis C2. The movable body14is made of an elastically deformable resin material, for example. Specifically, the movable body14is made of a material easily elastically deformed as compared to the barrel12.

The movable body14includes a main body14a, a seal body14bdisposed on the main body14a, and a flange14cdisposed on the main body14a.

The main body14aof the movable body14is cylindrical and has an outer diameter d2smaller than an inner diameter d1of the barrel12shown inFIG. 4. Therefore, while the movable body14is housed in the barrel12, a clearance is generated between the main body14aand the inner circumferential surface12eof the barrel12.

The seal body14bof the movable body14has a disk shape and has an outer circumferential end brought into close contact with the inner circumferential surface12eof the barrel12in a slidable and fluid-tight manner. Although the seal body14band the main body14aare integrated as one part, the seal body14band the main body14amay be separate parts.

For close contact of the outer circumferential end with the inner circumferential surface12eof the barrel12in a fluid-tight manner, the seal body14bhas an outer diameter d3larger than the inner diameter d1of the barrel12. The outer diameter d3of the seal body14bis larger than the outer diameter d2of the main body14aof the movable body14.

Additionally, the seal body14bhas a central portion attached to a front end of the main body14a(the end closer to the leading end12aof the barrel12). Additionally, an outer circumferential side portion of the seal body14bis away from the main body14awhen the portion is in a free state (when the movable body14is present outside the barrel12).

The flange14cof the movable body14is a projecting portion projecting from the main body toward the inner circumferential surface of the barrel12and is disposed at a rear end of the main body14a(the end closer to the base end12bof the barrel12). The flange14chas an outer diameter d4smaller than the outer diameter d3of the seal body14b. In the case of the first embodiment, the outer diameter d4of the flange14cis smaller than the inner diameter d1of the barrel12and larger than the outer diameter d2of the main body14a. The reason why the flange14cas described above is disposed on the movable body14will be described later.

For separable contact with the plunger16, the movable body14also includes a planar-shaped rear end surface14dorthogonal to the central axis C2and includes a non-penetrating hole-shaped guide hole14ein the rear end surface14d.

FIG. 7is an external view of the plunger.

As shown inFIG. 7, the plunger16is a member for pushing and moving the movable body14housed in the barrel12toward the leading end12a(i.e., the discharge port12c) of the barrel12, has a central axis C3, and is made of a resin material, for example. The plunger16is configured to come into separable contact with the movable body14.

Specifically, the plunger16includes a contact portion16acoming into contact with the movable body14on the front end side (the side closer to the leading end12aof the barrel12). The contact portion16ahas an outer diameter d5smaller than the inner diameter d1of the barrel12. The contact portion16aincludes a planar-shaped contact surface16bcoming into surface contact with the planar-shaped rear end surface14dof the movable body14.

The plunger16includes a guide pin16cprojecting from the contact surface16bof the contact portion16a. While the rear end surface14dof the movable body14is in surface contact with the contact surface16bof the plunger16, the guide pin16cis received in the guide hole14eof the movable body14. An outer diameter d6of the guide pin16cis smaller than an inner diameter d7of the guide hole14eshown inFIG. 6so that the guide pin is received in the guide hole14eof the movable body14in a manner enabling forward and backward movement. Since the guide pin16cis guided by the guide hole14e, the contact surface16bof the plunger16can appropriately come into surface contact with the rear end surface14dof the movable body14. Specifically, the movable body14and the plunger16can come into contact with each other in a state in which the central axis C2of the movable body14and the central axis C3of the plunger16are arranged substantially on the same straight line. As a result, the plunger16can push and move the movable body14toward the leading end12aof the barrel12without tilting.

According to the plunger16as described above, the movable body14can be pushed and moved toward the leading end12aof the barrel12by advancing the plunger16. Additionally, the movable body14and the plunger16can be separated from each other by simply retracting the plunger16.

Since the plunger16is not fixed to the movable body14while the seal body14bis in close contact with the inner circumferential surface12eof the barrel12, the plunger16possibly comes off from the barrel12. For example, if the injector10is in a state with the nozzle tip18located downward and a user grasps only the plunger16to lift the injector10, the barrel12may fall off from the plunger16due to its own weight.

To prevent the plunger16from coming off from the barrel12in this way, stoppers16dare disposed on the plunger16as shown inFIG. 7.

In the case of the first embodiment, the two stoppers16dare disposed oppositely to each other across the central axis C3of the plunger16. Each of the two stoppers16dis an elastically-deformable plate spring-shaped member including a fixed end16eattached to the plunger16and a free end16fdisplaceable in a radial direction of the barrel12(a direction orthogonal to the central axis C1of the barrel12). In the case of the first embodiment, the stoppers16dand the plunger16are integrated as one part.

In the case of the first embodiment, the free end16fof the stopper16dis located on the base end12bside of the barrel12with respect to the fixed end16e. The free end16fis farther than the fixed end16efrom the central axis C3of the plunger16. Therefore, the stopper16dextends from the leading end12aside to the base end12bside of the barrel12and toward the inner circumferential surface12eof the barrel12.

As shown inFIG. 7, a distance L1between the free ends16fof the two stoppers16dis larger than the inner diameter d1of the barrel12when the free ends are in a free state (when the plunger16is present outside the barrel12). Therefore, when the stoppers16dof the plunger16are located inside the barrel12, each of the two stoppers16dis elastically deformed by the inner circumferential surface12eof the barrel12such that the free ends16fcome closer to each other. This brings the free ends16fof the stopper16dinto elastic contact with the inner circumferential surface12eof the barrel12in the radial direction of the barrel12. As a result, a friction force is generated between the barrel12and the free ends16fof the stopper16d, and the plunger16is restrained from coming off from the barrel12. The term “elastic contact” as used herein means that a portion of an object during elastic deformation is in contact with another object in a restoring direction in which the object is restored to an original shape.

An elastic force of the stoppers16d, i.e., the friction force between the inner circumferential surface12eof the barrel12and the free ends16fof the stoppers16d, is at a level preventing the barrel12from coming off when a user grasps only the plunger16of the injector10in a posture with the nozzle tip18located downward, or at a level preventing the plunger16from coming off when a user grasps only the barrel12of the injector10in a posture with the nozzle tip18located upward. Additionally, this elastic force (i.e., friction force) is at a level allowing the user to push and move the plunger16toward the leading end12aof the barrel12. To achieve such an elastic force (i.e., friction force), the materials of the barrel12and the stoppers16d, the shape of the stoppers16d, etc. are appropriately selected.

According to the stoppers16das described above, the plunger16can be prevented from coming off from the barrel12without disposing a convex portion on the inner circumferential surface12eof the barrel12. Therefore, when the movable body14is housed into the barrel12, the seal body14bis not damaged by the convex portion disposed on the inner circumferential surface12e.

According to the stoppers16das described above, the plunger16can be anchored at an arbitrary position on the inner circumferential surface12eof the barrel12. As a result, the injector10can have high usability.

Furthermore, in the case of the first embodiment, the two stoppers16dare arranged oppositely to each other across the central axis C3of the plunger16, so that the central axis C3of the plunger16can be aligned with the central axis C1of the barrel12.

Although the free ends16fof the stoppers16dare in elastic contact with the inner circumferential surface12eof the barrel12, if the user moves the plunger16backward, the free end16fslides on the inner circumferential surface12e, and the plunger16finally conies off from the barrel12. To deal with such coming-off due to the user, as shown inFIG. 4, the circumferential groove12fis formed in a portion near the base end12bin the inner circumferential surface12eof the barrel12. The free ends16fof the stoppers16dengage with (fall and fit into) the circumferential groove12f, so that the plunger16is restricted from moving toward the base end side of the barrel12, and as a result, the plunger16is prevented from coming off from the barrel12.

When the plunger16is housed into the barrel12, the free ends16fof the stoppers16dmay be caught in the circumferential groove12f, which possibly makes it unable to smoothly move the plunger16toward the leading end12aof the barrel12. As a countermeasure, as shown inFIG. 4, the circumferential groove12fincludes a slope surface12gextending from a bottom potion thereof toward the leading end12aof the barrel12and sloping with respect to the inner circumferential surface12e. Due to the slope surface12g, the free end16ffalling into the circumferential groove12fcan return onto the inner circumferential surface12e. As a result, the free ends16fof the stoppers16dcan pass through the circumferential groove12fwithout being caught.

When the movable body14is housed into the barrel12, the slope surface12gcan also prevent the seal body14bof the movable body14from being caught in the circumferential groove12f. As a result, the seal body14bcan be prevented from being damaged by the circumferential groove12f.

While describing the operation of the injector10according to the first embodiment, other features of the injector10will hereinafter be described with reference toFIGS. 8A to 8D.

FIG. 8Ais an enlarged cross-sectional view of the barrel while the plunger and the movable body are stopped.

As shown inFIG. 8A, the seal body14bof the movable body14is in close fluid-tight contact with the inner circumferential surface12eof the barrel12, so that a fluid F is contained in the barrel12without leaking from the base end side of the barrel12to the outside.

FIG. 8Bis an enlarged cross-sectional view of the barrel during movement of the plunger and the movable body toward the leading end of the barrel.

As shown inFIG. 8B, while the rear end surface14dof the movable body14and the contact surface16bof the plunger16are in contact with each other, the movable body14is pushed and moved toward the leading end12aof the barrel12by the plunger16. During movement of the movable body14, the seal body14bis elastically deformed. Specifically, due to the friction force generated between the outer circumferential end of the seal body14band the inner circumferential surface12eof the barrel12, the seal body14bis elastically deformed such that the outer circumferential side portion of the seal body14bapproaches the main body14a. The seal body14bmoves in this elastically deformed state and pushes and moves the fluid F toward the discharge port12c.

FIG. 8Cis an enlarged cross-sectional view of the barrel during movement of the plunger in a direction away from the movable body.

As shown inFIG. 8C, when the plunger16moves in a direction away from the movable body14, i.e., toward the base end of the barrel12, the movable body14is separated from the plunger16and stops in the barrel12in this state.

Immediately after the movable body14stops, as shown inFIG. 8A, the seal body14bis returned (restored) to the original shape with the outer circumferential side portion separated from the main body14a. In this case, the movable body14entirely retracts toward the base end of the barrel12without changing the contact position on the inner circumferential surface12eof the barrel12in contact with the outer circumferential end of the seal body14b. As a result, the fluid F in the nozzle tip18is drawn toward the seal body14b, and the subsequent dripping of the fluid F is suppressed.

To allow the movable body14to retract toward the base end of the barrel12through the restoration of the seal body14bwithout changing the position of contact of the seal body14bwith the barrel12, the plunger16needs to retreat at the same time. In other words, a restoring force of the seal body14bneeds to exceed the friction force between the free ends16fof the stoppers16dof the plunger16and the inner circumferential surface12eof the barrel12. For this purpose, the material of the seal body14b, the shape of the seal body14b, etc. are appropriately selected.

When the movable body14retracts through the restoration of the seal body14bwithout changing the position of contact of the seal body14bwith the barrel12as described above, the flange14cis moved along the inner circumferential surface12eof the barrel12. As a result, the movable body14can retreat in the extending direction of the central axis C1of the barrel12. If the flange14cdoes not exit, the movable body14retracts in a direction tilted with respect to the central axis C1of the barrel12, so that the movable body14may have a posture in which a portion of an outer edge of the rear end surface14dcomes into contact with the inner circumferential surface12eof the barrel12, i.e., a tilted posture. If the movable body14is tilted, the adhesion between the seal body14band the inner circumferential surface12eof the barrel12is partially weakened, so that the fluid F may leak to the base end side of the barrel12.

In the case of the first embodiment, the outer diameter d4of the flange14cof the movable body14is smaller than the inner diameter d1of the barrel12. Therefore, the flange14ccan be moved without strong contact with the inner circumferential surface12eof the barrel12, i.e., in a state of substantially zero friction force. Alternatively, the outer diameter d4of the flange14cof the movable body14may be equal to or larger than the inner diameter d1of the barrel12. However, the friction force between the flange14cand the barrel12must be smaller than the friction force between the seal body14band the barrel12. Otherwise, the restoration of the seal body14band the retraction of the movable body14due to the restoration cannot be achieved.

In the case of the first embodiment, as shown inFIG. 6, the distance L2between the seal body14band the flange14cin the movable body14is made larger than the outer diameter d3of the seal body14b. Therefore, when the movable body14retracts due to the restoration of the seal body14b, the movable body14is hardly tilted (as compared to when the distance L2is smaller than the outer diameter d3).

As shown inFIG. 8C, the plunger16separated from the movable body14is kept housed in the barrel12by the stoppers16dwithout coming off from the barrel12.

FIG. 8Dis a partially enlarged cross-sectional view of the barrel while the plunger is restricted from coming off from the barrel by the circumferential groove.

As shown inFIG. 8D, the plunger16during retraction toward the base end of the barrel12due to pulling by the user is restrained by engagement of the free ends16fof the stoppers16dwith the circumferential groove12f. As a result, the plunger16is prevented from coming off from the barrel12.

According to the first embodiment as described above, the seal body can be housed into the barrel without damage and the plunger can be prevented from falling off from the barrel in the injector.

Second Embodiment

A second embodiment is substantially the same as the first embodiment as descried above except that the form of the stoppers disposed on the plunger is different. Therefore, the second embodiment will be described mainly in terms of different points. The same reference numerals are given to constituent elements in the second embodiment that are substantially the same as the constituent elements in the first embodiment described above.

FIG. 9is an enlarged cross-sectional view of a leading end side portion of a barrel in an injector according to the second embodiment.FIG. 10is an enlarged cross-sectional view of a base end side portion of the barrel.

As shown inFIG. 9, in an injector110according to the second embodiment, a plunger116includes stoppers116d. Each of the stoppers116dis a plate spring-shaped member including a fixed end116eattached to the plunger116and a free end116felastically contacting the inner circumferential surface12eof the barrel12.

In the case of the second embodiment, unlike the stopper16dof the first embodiment, the free end116fof the stopper116dis located on the leading end side of the barrel12with respect to the fixed end116e. Therefore, a contact surface116bof the plunger116coming into contact with the rear end surface14dof the movable body14is closer to the free end116fof the stopper116das compared to the first embodiment shown inFIG. 8D.

Thus, as shown inFIG. 10, when the free end116fof the stopper116dis engaged with the circumferential groove of the barrel12, the contact surface116bof the plunger116is located closer to the base end12bof the barrel12. In other words, the movable body14having the rear end surface14dbrought into contact with the contact surface116bis also disposed closer to the base end12bof the barrel12. As a result, a larger amount of the fluid can be contained in the barrel12.

In the second embodiment as described above, as with the first embodiment, the seal body can be housed into the barrel without damage and the plunger can be prevented from falling off from the barrel in the injector.

Third Embodiment

In the case of the first embodiment described above, the stoppers preventing the plunger from coming off from the barrel are disposed on the plunger. In contrast, in the case of a third embodiment, stoppers are disposed on the barrel. Therefore, the third embodiment will be described mainly in terms of the different stoppers. The same reference numerals are given to constituent dements in the third embodiment that are substantially the same as the constituent elements in the first embodiment described above.

FIG. 11is a partial cross-sectional view of an injector according to the third embodiment,FIG. 12is a cross-sectional view of the injector taken along a line A-A shown inFIG. 11.FIG. 13is an enlarged cross-sectional view of a barrel, showing stoppers when the movable body is housed into the barrel. InFIG. 11, the nozzle tip and the finger grip are not shown.

As shown inFIGS. 11 and 2, in an injector210according to the third embodiment, no stopper is disposed on a plunger216. Instead, as shown inFIG. 12, a pair of stoppers212ffacing each other is disposed on a barrel212.

Specifically, in the case of the third embodiment, the stoppers212fare made up of portions of the barrel212each interposed between two slits212gformed to extend from a base end212bof the barrel212, As a result, a portion of the barrel212interposed between base portions of the two slits212gis defined as a fixed end212hof the stopper212f. A claw212jbrought into elastic contact with the plunger216is disposed on the inner side of a free end212iof each of the paired stoppers212f. Therefore, the stopper212fis a plate spring-shaped member (a plate spring-shaped member integrated with the barrel212) having the fixed end212hattached to the barrel212and the free end212ibrought into elastic contact with the plunger216(via the claws212j).

A distance between the claws212jof the pair of the stoppers212fis made smaller than an outer diameter of a shaft portion216bof the plunger216. As a result, the pair of the claws212jholds the shaft portion216bof the plunger216. Consequently, the plunger216is prevented from coming off from the barrel212.

The planer216during retraction toward the base end212bof the, barrel212due to pulling by the user is restrained when a contact portion216afor contact with the movable body14is brought into contact with the claws212j. As a result, the plunger216is prevented from coming off from the barrel212.

As shown inFIG. 13, when the movable body14is housed into the barrel212, the pair of the stoppers212fis elastically deformed such that the free ends212imove away from each other. As a result, the movable body14can be housed into the barrel212without bringing the claws212jof the stoppers212finto contact with the seal body14b.

In the third embodiment as described above, as with the first embodiment, the seal body can be housed into the barrel without damage and the plunger can be prevented from falling off from the barrel in the injector.

Although the present invention has been described with three embodiments, the present invention is not limited to these embodiments.

For example, in the case of the first embodiment described above, the seal body14band the plunger16are separate parts; however, the embodiments of the present invention are not limited thereto. The seal body and the plunger may be integrated as one part.

Therefore, in a broad sense, the injector according to the embodiment of the present invention is an injector comprising a cylindrical barrel including a discharge port, a seal body coming into close contact with an inner circumferential surface of the barrel, a plunger for pushing and moving the seal body to the discharge port side of the barrel, and a stopper disposed on one of the barrel and the plunger and coming into elastic contact with the other in a radial direction of the barrel.

INDUSTRIAL APPLICABILITY

The present invention is applicable to any injector for injecting a fluid.

EXPLANATIONS OF LETTERS OR NUMERALS