RU2172638C2 - Disposable syringe with aspiration mechanism - Google Patents

Abstract

FIELD: subcutaneous injection equipment in medicine. SUBSTANCE: disposable syringe 10 has plunger 14 formed as stem equipped with ratchet teeth 28 made in the form of truncated cone or beams. Springy locking clamp 40 is freely hanging from plunger portion having ratchet teeth. Position of clamp 40 defines maximum value of dose that may be injected by means of syringe. Before filling syringe with medicinal preparation and dispensing it, aspiration gaps 114 may be formed on plunger stem upon user's request. During usage of syringe, first withdrawal of plunger from cylinder 12 is allowed for aspiration, with following filling of cylinder cavity with medicinal preparation due to radial flexure and sliding of tooth 83 of locking clamp 40 over ratchet teeth surfaces. Locking springy clamp 40 is held in predetermined site along cylinder length by means of contacting acute ends bent outside and incised into inner side wall of cylinder. Such construction prevents syringe from repeated usage. EFFECT: increased efficiency, simplified and low-cost manufacture method and enhanced reliability in operation. 19 cl, 34 dwg

Description

 This application is a partial continuation of the application N 08/195302 of February 14, 1994, “Disposable syringe kit” and the application of N 08/232749 of April 25, 1994 “Disposable syringe assembly containing a spring clamp stopper and plunger”. This description contains references to both of these applications, as if they were fully submitted.

 The present invention relates generally to hypodermic needles and syringes. More specifically, the invention relates to a spring locking clip and a corresponding plunger that can be used to turn the plastic cylinder of a hypodermic syringe into an inexpensive disposable syringe from a material approved for medical use, having a structure that makes it difficult to reuse it. In this invention, the term “single use” means that the full maximum dose drawn into the syringe can be administered to the patient only once. However, such a syringe allows the patient to be administered the drug repeatedly, but with the condition that each time only part of the total volume of the drug is injected, which can be drawn into the syringe with one full stroke of the rod in the cylinder in the proximal direction, i.e. "one-time use" means the possibility of a single delivery of the maximum dose of the drug for a given syringe and the possibility of using the syringe several times if each time a dose is less than the maximum. The total volume of doses given in the case of using a syringe several times cannot exceed the maximum or total dose collected in the syringe with one movement of the plunger in the cylinder in the opposite direction. The syringe is disposable if the maximum or full dose, determined by the capacity of the cylinder and / or the position of the spring clip on the plunger, is fully introduced to the patient at the first and only use of the syringe. After that, the spring clip moves to its extreme distal position and all attempts to reuse the syringe are blocked. If a medicine is introduced into the syringe in an amount less than the maximum dose, then the doses in the first and subsequent dispensations will be less than the maximum. The issuance of individual doses of the drug can be performed in only one full stroke of the plunger rod in the distal direction. The total amount of drug injected cannot exceed the capacity of the syringe barrel. A device of the type described is considered a disposable syringe.

 The safe one-time use of hypodermic needles and syringes with their subsequent withdrawal from circulation is directly related to people working in the field of medicine and health. Accidental injuries from a needle injection when using a syringe pose a significant risk to patients, doctors and nursing staff. This risk is associated with the widespread prevalence of HIV and hepatitis virus among the population. Therefore, extreme caution should be exercised when handling needles and syringes, and used needles and syringes should be removed from circulation. To solve this problem, the present invention provides a disposable needle and syringe assembly. According to the invention, a mechanism is provided to prevent further use of the needle and syringe (collectively referred to as the syringe together) after at least one use. Thanks to this, such a syringe will be removed from circulation rather than syringes that can be reused. In this way, the likelihood of cross-contamination of patients and drug users can be reduced.

The present invention provides a compact design and therefore can be used in syringes having an extremely small cylinder capacity, including syringes for administering small doses of the order of 0.1 cm ³ . In contrast to the invention, known devices, which will be described in more detail below, cannot be simply and / or economically reduced in size so as to preserve the effectiveness of the mechanism that prevents reuse. Therefore, syringes with cases with a capacity of less than 3 cm ³ are not manufactured by the industry. In known disposable syringes, in order to reduce the maximum dose of a conventional three-milliliter syringe to 1 cm ³ , the initial axial position of the locking mechanism in the cylinder is changed. However, it is desirable to have syringes of smaller capacity, which is determined not only by the position of the clamp, but also by the size of the syringe. However, the present invention can also be adapted to use syringe cylinders having a maximum dose of 3 cm ³ and other maximum dose values, although it can most successfully be used in syringes of small capacity, even of such small capacity as 1 cm ³ .

 Obviously, the low cost of syringes is essential to meet the needs of underdeveloped countries and reduce healthcare costs worldwide. Low cost would reduce the number of syringe reuse cases, which is currently the case with conventional syringes to be withdrawn from use. The possibility of infection as a result of repeated use of the same syringe by different patients could be excluded if there was a syringe that allowed only one use. In addition, this would reduce patient anxiety about the dangers of being infected with a used syringe.

 The present invention provides a simple and inexpensive mechanism for enabling only single or single use of a syringe (with or without a needle). Such a syringe is supposed to be assembled at the manufacturer and delivered to doctors, patients, etc. for use. The user fills the syringe with the appropriate medicine in the usual way, i.e. pulls the plunger in the cylinder, while the medicine is absorbed through the tip for the needle nozzle into the cylinder cavity. According to the present invention, before filling the cylinder with medicine, the plunger can be repeatedly moved in both directions for aspiration. If the user decides that a sufficient number of suction strokes has been made, then by forcing the plunger to move, the locking mechanism is activated, which makes the syringe disposable. After that, in the usual way, the needle is inserted under the patient’s skin and the plunger is manually moved in the cylinder, which leads to the piston moving to the distal end of the syringe and the drug is forced out through the needle tip.

 According to the present invention, during the administration of the dose of the drug, the locking spring clip moves with the plunger rod, which will be described in more detail below. When the clamp reaches a distal position, the blocking or contact sharp ends abut against the inner side wall of the cylinder, and the piston is adjacent to the base of the blocking spring clip. As a result, the second extension of the plunger in the cylinder is blocked. Thus, another dose of the drug cannot be introduced into the syringe, which excludes the possibility of its reuse. The disposable syringe offered is simple and cheap. The blocking mechanism preventing reuse acts automatically, i.e. it provides blocking of the plunger without the need for the user to perform any manipulations to actuate this mechanism.

 The subject of numerous inventions and developments is the design of the disposable syringe assembly, which could not be reused. Such a syringe should be easy to manufacture and assemble, operate in the usual way and be able to dispense different volumes of liquid. The syringe should be made of materials universally approved for use in medicine. Preferably, the syringe can be manufactured on standard equipment that is currently used to make syringes, and finally, it is important that its cost is low.

 The foregoing objectives are achieved in the present invention using a new and one-of-a-kind plunger in combination with a new and one-of-a-kind spring lock clip. The plunger has a plurality of cylindrical ratchet teeth, more specifically ratchet teeth, having the shape of a truncated cone or, in an alternative embodiment, having the shape of beads. The spring clip is installed by the manufacturer in a specific place along the axis of the plunger to limit the maximum length of its extension in accordance with the required dose. According to a preferred embodiment of the invention, at least between the two ratchet teeth or beads there is a longitudinal gap for pulling and moving the plunger forward without corresponding movement of the spring clip. This allows the syringe to be aspirated before it is filled with medicine. The use of ratchet teeth in the form of beads instead of the ratchet teeth in the form of a truncated cone, described in the known patents, provides a smoother extension of the plunger during syringe operation, while the force required to extend is much less than when the ratchet teeth have the shape of a cone or a truncated cone .

 There are technical specifications developed by the International Organization for Standardization, for the maximum value of the pulling force of the plunger in a hypodermic needle equipped with a needle. The disposable syringe designs proposed in previous applications N 08/195302 of 02/14/1994 and N 08/232749 of 04/25/1994 were tested, as a result of which it was found that in some syringes the pulling force of the plunger slightly exceeded the maximum value specified in technical conditions, although in most syringes this force was less than the maximum allowable value. To provide a high quality product that always meets the standard, the present invention has been improved. Obviously, a new standard maximum value of the pulling force of the plunger in disposable syringes could be set as a parameter, since the current standard relates to disposable syringes that can be used repeatedly.

 According to a preferred embodiment of the present invention, the ratchet teeth of the plunger are in the form of beads. In this case, when pulling the plunger rod, the spring clip, in contrast to the device described in previous applications, moves along the ratchet teeth not intermittently, but glides more smoothly on the surface of the beads. The pulling force is reduced and is almost the same as in reusable syringes with plungers that do not have a spring-loaded locking clip.

 It is desirable to have a syringe with a spring-loaded locking clip that allows multiple aspiration. In the invention described in previous applications, multiple aspiration was not provided (i.e., multiple reciprocating movement of the plunger to suck air into the cylinder and then expel it from the cylinder), but limited aspiration was allowed in those cases when the initial stretching and backward movement of the plunger, the spring clip moved to a position that is not the extreme distal or forward position.

 The present invention allows multiple aspiration. There is a gap between the ratchet teeth in the syringe, and when the spring clip is between the ratchet teeth, i.e. in this gap, no movement of the plunger causes the spring lock clip to move forward. Obviously, the length of the gap between the ratchet teeth determines the amount of aspiration.

The use of a new design plunger and spring locking clip prevents reuse of the syringe. Such a design can be installed even in syringes with a cylinder capacity of 0.1 cm ³ without any deterioration in their effectiveness or safety. The proposed working mechanism allows the manufacture of syringes having an extremely small capacity, while maintaining their performance. In contrast, interlocking devices of known disposable syringes include various mechanisms that prevent the manufacture of very small volume syringes. The present invention is economical to manufacture, has protection against unblocking, allows you to enter the medicine using conventional techniques, is made from materials approved for use in medicine, and can be manufactured on standard equipment.

 In the present invention, the pulling force of the plunger is within acceptable limits set for refillable syringes, although the proposed syringe is disposable. The mechanical pulling of a plunger having bead-shaped teeth occurs more smoothly compared to a plunger having ratchet-shaped ratchet teeth in the form of a truncated cone. In addition, the presence of one or more spaces between the ratchet teeth allows for selective and repeated aspiration.

 A characteristic feature of the present invention is the implementation of the part of the plunger in contact with the thumb in the form of a tear-off disk. After using the syringe, the user can simply bend or twist this disk and separate it from the plunger, thereby creating an additional obstacle to reuse of the syringe. The ease of separation of the disc from the plunger rod allows the use of torn discs to account for the consumption of syringes.

 Various approaches to solving this problem, proposed in patent documents and other publications, are usually limited to a description of the mechanisms for disposable syringes without taking into account their geometric characteristics, such as the minimum total capacity that a syringe barrel may have. Obviously, for single-use syringes, there is a certain minimum capacity, which depends not only on the design, but also limited by technological capabilities due to the small size of the syringe. In existing medical practice, for the introduction of small doses, drugs prefer to use syringes with a lower full capacity instead of limiting the stroke in syringes with a larger cylinder capacity, since in the first case the accuracy of the syringe is higher and easier to use. Unlike known syringes, the present invention uses a completely different mechanism and a different blocking force to block syringe reuse. This allows you to create the design of syringes of very small capacity.

 Previously, safe syringes were made, providing some protection against accidental needle injuries. Such constructions require rather complex mechanisms or have a relatively large volume, and their manufacture is often associated with relatively high costs. Most of the known mechanisms limiting the use of syringes to one time are intended for use with a standard X-shaped plunger of known syringes. Unlike known devices, the present invention provides for the use of a completely new plunger, the main configuration of which is a rod equipped with ratchet teeth, preferably in the form of beads. In addition, security mechanisms in known devices can sometimes fail or be disabled intentionally. According to the applicant, the invention is more effective in preventing reuse of the syringe.

However, as indicated above, it is especially important that the present invention is extremely effective, inexpensive and suitable for installation even in syringes, the capacity of which corresponds to a maximum dose of 1 cm ³ . This means that such a device can be installed in syringes for very small doses, which is highly desirable. Unlike the present invention, reducing the size of known disposable syringes or “safe” syringes is hardly possible and at least difficult. Such syringes with a capacity corresponding to a maximum dose of 0.1 cm ³ are not manufactured by industry; instead, manufacturers prefer to use standard syringes with a larger cylinder (e.g. 3 cm ³ ), decreasing the stroke of the plunger to limit the maximum dose. Therefore, a particular objective of the present invention is to provide a disposable syringe having a small maximum capacity of the order of 0.1 cm ³ , and this goal should be achieved primarily by reducing the size of the cylinder, and not by positioning the spring lock clip.

Known approaches to the design of disposable plastic syringes can be classified as follows:
(a) blocking the plunger after dispensing the drug,
(b) disconnecting the plunger,
(c) retracting the needle into the cylinder after dispensing a dose of the drug,
(d) physical destruction of a portion of the syringe,
(e) the use of chemicals to render the syringe unusable after first use; and
(e) the use of additional means, such as bushings, to prevent reuse of the syringe and at the same time to protect against needle stick.

 As shown in the following description, in the proposed syringe, the plunger is blocked from further use mechanically using a new spring locking clip.

 Known locking mechanisms generally worked on known X-shaped plungers, and in some cases on a cylindrical plunger. When using the X-shaped plunger, its alignment with the cylinder was ensured by the edges of the X-shaped profile. In the case of using a locking device on a cylindrical plunger, these devices were symmetrical and completely covered the plunger. Thus, the alignment of these plungers with the cylinder blocking mechanism was not violated. The position of the X-shaped plunger with a locking clip coaxial with the cylinder, as well as the cylindrical plunger with a locking clip covering it, prevented a desirable decrease in the maximum capacity of the syringe.

 Unlike known devices, the present invention provides a new type of locking mechanism mounted on a substantially cylindrical plunger. The design and principle of operation of the proposed spring locking clamp provide a radial displacement of the axis of the plunger inside the cylinder. This misalignment of the plunger and cylinder allows the manufacture of disposable syringes having a significantly lower capacity than was previously possible.

 In US Pat. No. 4,386,606, sharp edges made on the plunger, cam, or cylinder are used to securely lock the syringe having an X-shaped plunger.

 US Pat. No. 4,376,738 describes a non-reusable syringe in which there are many rigid, folding, sharp protrusions.

 US Pat. No. 4,731,068 describes rigidly fixed star-shaped teeth mounted on a cylindrical plunger to block the syringe after dispensing and prevent reuse.

 US Pat. No. 4,952,206 uses tines with which a washer located inside the valve prevents fluid from flowing after dispensing.

 US Pat. No. 4,961,728 uses non-parallel teeth on a blocking member for an X-shaped plunger.

 US Pat. No. 4,979,943 has a reversible locking element which allows the plunger to move in only one direction.

 US Pat. No. 5,000,737 uses an annular or notched gear stop interacting with an X-shaped plunger.

 US Pat. Nos. 5,021,047 and 5,138,466 use blocking teeth surrounding the plunger all around. The movement of the stopper in relation to the plunger leads to the bending of the stopper in the axial direction during its forced passage through the ratchet teeth.

 US Pat. No. 5,205,825 uses an insert clip to block X-shaped plungers.

 WO 89/00432 uses a plunger and a ratchet tooth wall to prevent reuse of the syringe.

 US patent N 5000737 relates to a disposable syringe to be withdrawn from use after use. The device shown in the drawings is intended for installation on the X-shaped rods of known plungers. The outwardly oriented sharp edges of the proposed groove are designed to be inserted into the inner cylindrical side wall or surface of the cylinder, which prevents the disk from moving relative to the cylinder when the plunger rod is moved in the proximal direction (i.e., corresponding to the absorption of the drug into the cylinder). The inward-oriented edges are designed to engage with adjacent walls of the X-shaped plunger, so that when the plunger moves in the distal direction (for dispensing medication), the device moves with it. FIG. 8-16 relate to the invention of patent N 5000737. Such a device is intended to be held in a quadrant of a cylinder bounded by an X-shaped plunger element. As indicated in the patent, this device has an elongated shape, i.e. its length exceeds the width.

In contrast to this device, the spring locking clip according to the present invention is not elongated, as will be shown in detail below. This clamp is compact and can be easily made for small syringes. Making it cheaper and easier. It does not fail in case of misalignment along the axis of the cylinder, but rather works efficiently due to misalignment. This design and principle of operation can significantly reduce the capacity of the syringe compared with the designs of known syringes. In addition, the present invention provides for the use of such a clamp together with a plunger of a new design. The proposed spring locking clip is not located in the quadrant of the cylinder defined by the X-shaped plunger, but only partially covers a practically cylindrical plunger of a new design located inside the cylinder. This contributes to a more uniform pressure of the locking mechanism on the inner side wall of the cylinder and ensures the effectiveness of the present invention in preventing reuse of a disposable syringe. The method of operation of the mechanism, consisting in the fact that the plunger is diverted from the center or is removed from a position coaxial with the cylinder, has significant advantages over the known devices. US Pat. No. 5,000,737 also describes a disc-shaped element that works in much the same way as the groove described in the same patent, and which is also intended for use with known X-shaped plungers. But in this case, the reduction in the size of the specified element, necessary for use in syringes with a capacity of 0.1 cm ³ , is difficult.

 US Pat. No. 5,151,088 also describes a disposable safety syringe assembly with a needle. The syringe has a small, rigid shield for the needle, retractable inward. After the injection, the shield extends to the locked position, in which it closes the needle. The shield accepts this position only if the user moves the plunger past the point corresponding to the zero volume of the syringe cavity. If the user does not knowingly or accidentally do this, the shield will not prevent reuse of the syringe. The aim of the present invention is to provide automatic locking of the syringe to prevent reuse after suction is performed, which avoids the transfer of infection from one person to another as a result of reuse of the needle. The device described in US Pat. No. 5,151,088 does not automatically trigger a blocking mechanism. A user who wants to reuse such a syringe can avoid the action of the blocking mechanism if he deliberately does not move the syringe plunger past a point corresponding to a zero volume.

US Pat. No. 5,205,825 relates to an insertion member serving to prevent the reuse of plastic syringes. This device, similar to the device described in US Pat. No. 5,000,737, has a locking mechanism designed to be installed in existing conventional syringes by inserting the device onto a standard X-shaped plunger inside the plastic barrel of the syringe. The above comments regarding the device of US Pat. No. 5,000,737 also apply to the device of US Pat. No. 5,205,825, namely:
- such a device cannot be performed with small dimensions while maintaining its effectiveness for installation in syringes with a low maximum dose and
- the advantages achieved by the present invention are the result of removing the plunger from a coaxial position relative to the axis of the cylinder.

 US Pat. No. 5,067,942 relates to a disposable hypodermic needle. When the needle assembly is connected to the syringe, two tabs are held inside the basket, whereby the sheath is pulled inward, opening a channel inside the needle for fluid to flow. After disassembling the syringe, the legs are separated from the basket and broken so that subsequent retraction of the shell becomes impossible. Compared with this device, the present invention is much simpler, cheaper to manufacture, more automatic and can be more easily adapted for small syringes.

 A variety of safety syringe designs have also been proposed, including needle closure means. US Pat. Nos. 4,909,791 and 4,982,842 provide clamping elements mounted to rotate on the syringe barrel and cover the needle after use.

 US Pat. No. 4,969,877 describes a syringe assembly in which there is an outer casing surrounding the inner cylinder or a syringe portion that slides in the outer casing, moving into the working position and into the retracted position, respectively, in the front and rear ends of the outer casing.

 US Pat. No. 4,013,073 describes a disposable flattening syringe in which the inner side of the collapsible wall is designed so that when the walls are compressed to displace the drug, they close and the syringe becomes unusable.

 US Pat. No. 4,022,206 describes a method and apparatus for storing and dispensing a vaccine in a single dose packaging system. This patent does not provide any measures to bring the device into an inoperable state to prevent its subsequent use.

 US Pat. No. 4,391,273 describes a rigid-type syringe, including a puncturer mounted on a piston and piercing the bottom of the cylinder after an injection is performed, which also leads to inoperability of the syringe after first use. In another embodiment of the syringe, a knife is proposed that allows the piston to move forward, however, when you try to take the piston back and reuse the syringe, this knife cuts the side wall of the cylinder.

 Known devices for preventing reuse of syringes contain various devices that block the plunger after the first filling of the syringe with medicine and the subsequent movement of the plunger by the stroke length to complete the injection. For example, US Pat. No. 4,731,068 describes a blocking device comprising a girdle or sleeve mounted at the outlet end of a syringe and having dimensions that allow it to frictionally slide along the inner wall of the cylinder. A star-shaped element is fixedly mounted on the plunger, the sharp ends of which interact with the sleeve. When the plunger is first pulled out, the star-shaped element and sleeve move with it to the end of the syringe. When the plunger moves to the outlet end of the syringe, the sleeve remains at the distal end due to its frictional engagement with the inner wall, while the star-shaped element moves forward with the plunger. In the second attempt to pull the plunger, the sharp ends of the star-shaped element, which are not held more by the sleeve, will engage with the inner wall, preventing pulling.

 In an alternative embodiment of the locking device described in US Pat. No. 4,731,068, there is a sleeve mounted on the plunger with the possibility of sliding and engaged with a star-shaped element, which is provided with curved spring teeth mounted at the distal end of the syringe. When the plunger is first pulled out, the sleeve remains engaged with the star-shaped element, and when the plunger is first lowered, it moves in the direction of the outlet end and releases the teeth of the star-shaped element. When trying to re-pull the plunger, these teeth engage with the plunger, preventing it from being pulled.

 Other devices, such as those described in US Pat. Nos. 4,781,684, 4,493,703, 4,391,272 and 4,376,738, have a modified plunger or syringe wall that allow the plunger to move in only one direction and block the plunger or render it inoperative after its first lowering. They also apply to single-use syringes.

 US Pat. No. 5,290,235 relates to a reusable syringe. When using a syringe, the blocking element interacts with the guide device of the plunger and the inner surface of the hollow body of the syringe, allowing you to perform the first suction stroke and pumping stroke of the plunger, but preventing the possibility of re-suction stroke.

 The device described in US patent N 5290235, in General, is a conventional syringe with a hollow body. To facilitate piston movement, an elongated plunger rod protrudes from the housing. The rod has a guide bearing a blocking element in the form of a plate with at least one serrated protrusion facing the inner surface of the cylinder. The guide provides a relative rotation of the blocking element from the first position, in which the plunger moves freely in the distal direction, into the second position, in which the tooth (teeth) engage with the inner wall of the cylinder.

 The device described in US Pat. No. 5,290,235 is much more complex in construction than the present invention. The invention provides for the use of a plunger rod, which can be easily manufactured by molding and has an almost cylindrical shape, but is equipped with ratchet teeth. A spring clip is installed on the rod, the initial position of which will determine the maximum volume of liquid. In contrast to the invention, the device described in patent No. 5290235 has a complex plunger and is disadvantageous for mass production. The present invention allows the use of the same plunger rod in syringes designed for different maximum doses. In the patent N 5290235 in syringes with different maximum capacities, there must be a different distance along the length of the plunger between the first surface 22 and the thrust surface 26.

The present invention is extremely simple to manufacture and assemble. It can be used with cylinders of standard sizes, and also, which is important from a commercial point of view, it can be reduced in size for use in syringes with a low maximum dose of about 0.1 cm ³ . The present invention is reliable and essentially automatic, and in a preferred embodiment, as will be described in more detail below, has several locking mechanisms that make it impossible to reuse the syringe. The invention allows you to choose the location of the spring blocking clamp on the cylindrical rod of the plunger along its axis, which allows the manufacturer to produce syringes with different maximum doses at the same cylinder and rod sizes. Thus, the installation of a locking spring mechanism in a certain position relative to the cylinder and plunger during the manufacture of the syringe ensures that the doctor, nurse or user cannot enter an excessive dose of the drug. Since the spring locking clamp can be installed on the plunger in various initial positions, the cost of manufacturing a syringe is reduced, since it is sufficient to produce cylinders and plunger elements of only one size. The initial position of the spring locking clamp or mechanism on the plunger determines the maximum dose that can be entered by this syringe. Thus, the present invention has a mechanism that serves not only to prevent reuse of syringes, but also to limit the amount of drug that can be administered by syringe.

 The present invention provides additional opportunities to bring the syringe inoperable after its first use, which will be discussed in more detail below. This feature of the invention is associated not with the presence of any automatic device, but with the fact that the plunger disk, intended for contact with the user's thumb, can be torn off the stem, as a result of which the syringe becomes completely unusable. The disc separated from the plunger serves another purpose, namely, it makes it easier to inventory syringes, i.e. used syringes are discarded, and their discs are left to control the use of syringes.

 Another objective of the present invention is the creation of another blocking mechanism that prevents reuse of the syringe. In this embodiment, moving the plunger to its extreme distal position in the cylinder causes the annular male part of the above plunger disk, made in the form of a dovetail, to engage with the annular female cylinder device, also made in the form of a dovetail, and is mechanically blocked. This ensures complete locking of the disc and the rod inside the cylinder and prevents the possibility of the rod moving outward. This eliminates the possibility of drug absorption into the cylinder body, which makes the device unsuitable for reuse.

The configuration of the proposed device allows the manufacture of syringes with small maximum doses of the order of 0.1 cm ³ . As will be shown below, this is possible due to the fact that the locking device acts in the radial direction, i.e., moves the plunger rod away from the cylinder axis. With this method of operation, it is necessary that the spring clip has the same thickness, and it is not required that the clip completely surround the plunger rod. The design and principle of operation of the rod, cylinder and locking clamp allow them to be made with small dimensions that correspond to the small maximum cylinder capacity of 0.1 cm ³ , without compromising the performance of the syringe. Known syringes do not have such capabilities.

The present invention relates to a disposable syringe in which a mechanical interlock is provided to prevent reuse. The aim of the invention is to create a simple in design and cheap to manufacture a disposable syringe in which an attempt to reuse is automatically blocked. Another objective of the invention is to provide a cheap syringe with a mechanical interlock that does not allow reuse, which may have a capacity corresponding to very small doses. For example, a particular objective of the present invention is to provide a disposable syringe with such a small maximum dose as 0.1 cm ³ .

 Another objective of the invention is the creation of a disposable syringe, in which the mechanical movements of the elements are performed smoothly, and the pulling force of the plunger is less than the maximum industrial standards.

 A further object of the invention is to provide a disposable syringe in which multiple aspiration can optionally be performed before filling the cylinder with medicine.

 Another objective of the present invention is to provide an inexpensive spring-type mechanism which, when mounted on a plunger rod equipped with ratchet teeth, limits the amount of drug that can be drawn into the syringe barrel for subsequent injection. The initial position of this spring locking mechanism on a cylindrical rod with ratchet teeth determines the maximum capacity of the syringe. Therefore, a particular object of the invention is to provide a disposable syringe that can have various maximum doses depending on the initial axial position of the spring locking clip on the plunger rod. This allows the use of cylinders of the same size, which makes it possible to reduce the cost of manufacturing a syringe.

The next objective of the invention is the creation of a disposable syringe, the design of which makes it difficult to intentionally violate its blocking function. Another objective of the invention is the creation of a disposable syringe, in which the lock is performed by radial displacement of the plunger relative to the axis of the cylinder. This is partly ensured by the use of a new plunger rod, which is not X-shaped, but made essentially in the form of a rod, and by using a locking clip in the form of a spring, which can be mounted on the rod and bent in and out. The lack of alignment of the cylindrical rod of the plunger with the inner wall of the cylinder allows to reduce the size of the locking mechanism, providing a one-time action for installation in syringes with small doses of about 0.1 cm ³ . A particular objective of the invention is the creation of a locking mechanism for disposable syringes, which can be installed on the cylindrical rods of the plungers. Due to the absence of an X-shaped plunger in the proposed syringe, it is easier to manufacture with small dimensions. Due to the presence of ratchet teeth on the plunger rod and the spring blocking clamp, in the present invention there is no need for the blocking clamp to surround the cylindrical piston rod, as is done in known constructions. This allows the manufacture of syringes of very small capacity.

 According to the present invention, in a preferred embodiment, the plunger shaft also contains many ratchet teeth in the form of beads. As will be described in more detail below, in the initial position, the spring locking clip must be installed on one of the selected teeth or beads of the plunger. Due to this, the present invention provides the possibility of a more accurate dosage in comparison with known devices. The mechanical coupling between the spring locking clip and the plunger allows you to immediately enter a fixed maximum dose, in contrast to the known devices in which the maximum dose is adjusted by sliding the groove along the X-shaped legs of the plunger in different positions, which is far from easy to control.

 The next objective of the present invention is also the implementation of the plunger disk in contact with the thumb, that this disk at the request of the user can be bent or twisted and separated from the plunger rod after using the syringe. Thus, this disk can be used to account for the use of syringes and inventory. In addition, the separation of the disc from the plunger rod makes the syringe even more unsuitable for reuse.

 A further object of the invention is to provide another blocking mechanism that further prevents the reuse of a disposable syringe. This mechanism is formed by the interacting annular male part of the disk intended for contact with the thumb and the annular female receiving part at the proximal end of the cylinder. The male portion of the disk and the female portion of the cylinder each have a dovetail shape. The full cycle of the reciprocating movement of the plunger rod relative to the cylinder leads to mechanical blocking of the rod in the extreme distal position, which makes it impossible to re-stretch it relative to the syringe barrel.

 Another objective of the present invention is to provide a mechanism by which it is possible to limit the volume of the syringe so that syringes with the same size can accommodate and dispense different doses, thereby reducing the need for syringes of different sizes.

 The present invention is directed to a mechanism in which a ratchet plunger and a locking spring clip are used to achieve the above objectives. The operation of the syringe assembly is based on the loose contact of the spring blocking clamp with the plunger, which allows aspiration, if necessary, and filling the syringe with medicine when the plunger is pulled. The clamp has an approximately semi-cylindrical shape and can bend radially inward and outward. The clamp has teeth bent outward, which can bend quite independently from each other in accordance with a change in the diameter of the cylinder due to manufacturing tolerances or surface defects. There are also centering elements on the clamp to center it while advancing towards the needle. These elements further hold the locking mechanism embedded in the cylinder wall while attempting to pull the plunger to refill the syringe, as described below. The plunger has a front seal, which ensures smooth operation of the mechanism by applying a uniformly distributed load to the teeth crashing into the wall with any attempt to re-pull the plunger after the first dispense of the medicine.

 According to a preferred embodiment of the invention, there is a gap between adjacent ratchet teeth, allowing the suction plunger to be partially extended. After aspiration, the plunger continues to be pulled out to fill the syringe, while the spring locking clamp, although it is fixed in the cylinder, slides over one or more ratchet teeth of the cylindrical plunger due to its radial flexibility. Due to the fact that the clamp is open on the side and has a shape close to semi-cylindrical, it can adapt to changing the diameter of the teeth of the plunger. When fluid is dispensed by moving the plunger and piston to the front end of the syringe, the clamp bends radially. The plunger moves or pushes the clamp in the cylinder forward. After the injection, the plunger is in its frontmost position, while the clamp prevents the plunger from being pulled back again, since the clamp teeth cut into the plastic wall of the cylinder. Any attempt to overcome the adhesion of the teeth to the wall leads to a rupture of the plunger rod, since the tensile strength of the rod, reduced by reducing its cross section in certain places, is less than the frictional resistance exerted by the teeth embedded in the inner wall of the cylinder. In other embodiments of the invention, for a more reliable protection against reuse of the syringe, a second section of a plunger with a smaller diameter or several such sections can be made.

 In alternative embodiments of the invention, the plunger rod may have several gaps between adjacent ratchet teeth. This allows you to use the syringe a certain number of times with the execution, at the choice of the user, aspiration.

 An object of the present invention is to provide a syringe that can be manufactured using standard molding and assembly technology at a cost comparable to the cost of manufacturing currently available disposable plastic syringes.

 The aim of the invention is also to achieve the smooth operation of the syringe. Bead-shaped ratchet teeth provide smooth movement of the plunger and less force to pull the plunger out of the cylinder than the maximum value specified by industry standards. The aim of the invention is the creation of a disposable syringe that works without jamming, which is especially true for small volume syringes.

 Another objective of the invention is the creation of a plunger and a spring locking clip, made so that the positioning of the locking element and the locking of the plunger are achieved due to its radial bending and extension on the plunger inside the syringe barrel.

 The next objective of the invention is the creation of a spring locking clamp having flexible locking or contact sharp ends that can independently interact with the cylinder wall, the diameter of which can vary.

 A further object of the invention is to provide a syringe that becomes inoperative upon attempted reuse.

 The next objective of the invention is the creation of additional safety mechanisms, i.e. additional funds that do not allow to disable the blocking mechanism.

The next objective of the invention is to provide a syringe having the above features and capable of dispensing small doses of liquid of the order of 0.1 cm ³ with great accuracy.

 The aim of the invention is also to provide a syringe having the above features and capable of absorbing various predetermined maximum doses of liquid at the same size.

 The aim of the invention is also the creation of a syringe having the specified features, from materials permitted for use by official government regulations.

 The aim of the present invention is also to provide a syringe that can be modified in order to reduce the likelihood of accidental needle pricks.

 An object of the present invention is also to provide a disposable syringe in which, before filling with medicine, it is possible to aspirate one or more times with the same or different amount of intake air.

 The aim of the invention is the creation of several locking mechanisms that provide disruption of the syringe in various ways and prevent access to the working locking mechanisms.

 An object of the present invention is also to provide the possibility of dispensing various amounts of liquid and using a syringe several times, at the choice of the user, for a given cylinder diameter.

 The objectives, features and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment, accompanied by drawings.

 FIG. 1 shows a side view of the proposed syringe when the spring locking clip is in its initial position in which it hangs freely on the plunger rod provided with ratchet teeth. In this form, the syringe goes on sale from the manufacturer. The consumer must first fill the syringe with medicine, and then give the injection. The needle inserted into the syringe has the usual configuration.

 FIG. 2 shows in a perspective view a side view of the proposed syringe when it is filled with medicine and is ready for dispensing.

 FIG. Figure 3 shows the proposed syringe in a perspective view after dispensing the drug when the spring blocking clamp moved by one of the ratchet teeth of the plunger is in the forward or distal position.

 In FIG. Figure 4 shows how the plunger breaks when trying to re-move it in the proximal direction.

 FIG. 5 shows in a perspective view an embodiment of a plunger without a piston.

 FIG. 5a shows a perspective view of an elastic piston of a plunger mechanism.

 FIG. 6 shows a side view of a second embodiment of a plunger having two spaces between ratchet teeth with a reduced cross-sectional area.

 FIG. 7 shows a side view of a third embodiment of a plunger having one gap with a reduced cross-sectional area and a section with a larger cross-sectional area to prevent access to the blocking clip.

 FIG. 8 shows a side view of a fourth embodiment of a plunger having three sections with a reduced cross-sectional area, one of which is directly adjacent to the disk in contact with the thumb.

 FIG. 9 shows a top view of a flat spring locking clip prior to bending and giving it a three-dimensional shape for subsequent installation and use of a syringe in the cylinder.

 FIG. 10 shows a perspective view of a spring locking clip after being shaped.

 FIG. 11 shows a cross section along line 11-11.

 FIG. 12 shows, in cross-sectional side view, another embodiment of a cylinder, a plunger, and its disk in contact with the thumb.

 FIG. 13 shows a vertical section through a preferred embodiment of a syringe, the plunger of which is provided with ratchet teeth in the form of beads between which there is a gap for aspiration, wherein the syringe is shown in its initial position, i.e., until aspiration is performed, after which the medicine is drawn into the syringe.

 FIG. 14 shows a vertical section similar to FIG. 13, on which the plunger is partially elongated, i.e. moved in the proximal direction, for the first aspiration and subsequent administration of the drug into the syringe.

 FIG. 15 shows a vertical section similar to FIG. 13 and 14, on which the plunger is maximally extended, i.e. the spring blocking clamp passed along the surface of the ratchet teeth having the shape of beads, and the teeth of the clamp bent outward cut into the inner wall of the cylinder, which prevents further extension of the plunger and the blocking clamp. During this stroke, the medicine is completely absorbed into the cylinder, after which the syringe is ready to dispense the medicine.

 FIG. 16 shows a vertical section similar to FIG. 13-15, on which the plunger is fully advanced, i.e. is in a distal position after dispensing the drug. The locking spring clip due to contact with the base of the ratchet tooth is moved to the distal position with the plunger. Further extension of the plunger is not possible due to the insertion of the teeth of the spring clip into the side wall of the cylinder.

 FIG. 17 shows a vertical section similar to FIG. 13-16, in which the plunger is shown after a repeated attempt to pull it after it has been moved in the distal direction to the end for the first delivery of a full dose of the drug. The plunger is broken by a pulling force in excess of the tensile strength of the plunger. This force is less than the force with which the spring blocking clamp is held in the side wall of the cylinder, so the plunger rod breaks in the fault plane.

 FIG. 18 shows a vertical section similar to FIG. 13, which shows another embodiment of the syringe, in which the plunger has ratchet teeth in the form of beads and two spaces between the ratchet teeth for aspiration, which can be performed between two strokes of the syringe corresponding to the injection of the drug. This means that with this syringe two partial doses can be administered, each of which is preceded by an aspiration cycle. The syringe is shown in its initial position, i.e. before the first suction cycle is completed and before the plunger is at least partially pulled out of the cylinder.

 FIG. 19 shows a vertical section similar to FIG. 18, in which the plunger is partially elongated for aspiration before the cylinder is filled with medicine.

 FIG. 20 shows a vertical section similar to FIG. 18 and 19, on which the plunger is elongated from the cylinder so that its first ratchet tooth, made in the form of a bead, passed through a spring locking clip. With this position of the plunger, the medicine is inside the cylinder and the first dose of the drug is ready to dispense.

 FIG. 21 shows a vertical section similar to FIG. 18-20, in which the plunger is moved at full speed in the distal direction for the first time to dispense the entire dose of the drug in the cylinder. The locking spring clip is shown at a point located in the middle of the plunger rod, to which the clip has moved during the movement of the plunger. The syringe is ready for a second suction and dispensing of the medicine.

 FIG. 22 shows a vertical section similar to FIG. 19, on which the plunger rod is pulled out of the cylinder a second time to aspirate and fill the cylinder with a second dose of medication. With further pulling of the plunger, the spring locking clip passes through the ratchet tooth along its surface.

 FIG. 23 shows a vertical section similar to FIG. 18-22, on which the plunger rod is moved to a distal position for dispensing medication, while the spring locking clip moves with the rod.

 FIG. 24 shows a vertical section similar to FIG. 18-23, on which the plunger rod is fully displaced to the distal position, the entire drug is withdrawn from the syringe, and the spring locking clip is in the extreme distal position.

 FIG. 25 shows a vertical section similar to FIG. 18-24, in which the plunger rod is broken into two parts as a result of an attempt to pull the plunger. The pulling force exceeded the structural strength of the plunger rod, which led to its breakdown in the fault plane. The cutting force of the spring blocking clamp into the cylinder wall exceeds the tensile strength of the rod.

 FIG. 26-33 show other embodiments of the plunger rod, in which the number and position of the ratchet teeth, as well as the number, position and length of the spaces for aspiration, vary.

 The present invention relates to a syringe 10, which, as can be seen in the drawings, has a main cylindrical body 12 and a plunger element 14 mounted in the housing 12 with the possibility of sliding reciprocating movement. The preferred material for the cylindrical body is transparent polypropylene, used in medicine, which does not dissolve in most drugs, does not enter into a chemical reaction with them and is approved by the Department for Quality Control of Food, Drugs and Cosmetics. The preferred material for the plunger is polypropylene used in medicine, in which an appropriate additive has been added to impart brittleness to the polymer.

 A needle 15 is attached to the distal end of the syringe 10 in the usual way. It should be noted that the syringe and needle can be sold separately. The design of the needle and the method of attachment to the syringe are not important for a complete understanding of the invention. The needle 15 is mounted on the tip 18 of the cylindrical body 12. In this description, the end of the cylindrical body 12 facing the needle, as well as the direction or movement towards this end will be called distal. The other end of the syringe, i.e. the end of the plunger element 14, which has a disk 20 in contact with the thumb, and the protrusion 26 for the fingers, as well as the direction or movement towards this end will be called proximal. As can be seen in the drawings, the disk 20 is mounted on the proximal end of the plunger element 14 and serves to facilitate the pulling or movement of the plunger element 14 relative to the cylindrical body 12 in the proximal direction, as well as to facilitate the movement of the plunger element in the distal direction to the tip 18 of the cylindrical body 12 for removal medicines. When moving in the proximal direction, the syringe is aspirated and then the cylinder or cavity of the syringe is filled with medicine through the needle, and when moving in the distal direction, the medicine drawn into the syringe barrel is dispensed through the tip 18 and the needle 15. The drug is dispensed from the cylindrical body or cylinder of the syringe due to the sliding of the elastic piston 44 along the inner side wall 17 of the cylinder.

 The disk 20 in contact with the thumb is fixed to a portion 22 of the plunger element 14. In the embodiment of the invention shown in FIG. 8, section 22 is partially made in the form of a truncated cone with a fault plane 24 having a reduced diameter. The end face of section 22, having a reduced diameter, serves as the basis for the disk 20. After using the syringe, the disk 20 can be bent relative to the plane 24 and torn off, separated from the plunger element. The lack of disc 20 makes reuse of the syringe difficult. In addition, torn discs can be used to control the use of syringes.

 In FIG. 1-4, it is shown that the cylindrical body 12 has a protrusion or a supporting plane 26 for the fingers at its proximal end, which serves as a convenient supporting surface for the fingers when reciprocating the plunger element 14 relative to the cylindrical body 12 when using a syringe.

 In the basic configuration of the syringe, the plunger element 14 is a rod. Part of the length of the plunger element 14 is occupied by ratchet teeth 28 having the shape of a truncated cone. It is clearly seen in the drawings that each ratchet tooth 30 has an inclined surface 31 extending outward (from the proximal end to the distal end) and is connected by molding to an adjacent ratchet tooth base or common plane 32 having a larger diameter D1 (on the upper tooth) and a smaller one diameter D2 (on the lower tooth).

 In the embodiment shown in FIG. 13-32, the straight inclined surfaces 31 are replaced by convex surfaces. In this case, the ratchet teeth are made in the form of beads having a smooth surface for sliding the spring blocking clamp on it when moving the plunger in the proximal direction, as well as for moving the blocking clamp together with the plunger in the distal direction. Each of these ratchet teeth has a large diameter approximately in the middle between the teeth. This diameter corresponds to the diameter D1 of the ratchet teeth in the form of a truncated cone shown in FIG. 1. The spherical shape of the ratchet teeth provides a smoother extension of the plunger. In addition, the pulling force of the plunger is significantly reduced and is almost the same as in syringes without a spring locking clip.

 In the embodiment shown in FIG. 7, a seal 34 is mounted on the plunger element 14 immediately above the most proximal ratchet tooth. The seal 34 may be integral with the plunger by molding or, alternatively, may be a separate elastic part. A tight fit of the seal 34 (or of the plunger portion 22 shown in FIG. 1) in the cylinder allows you to restrict access to the spring locking clip and protect it from attempts to disable. Small tolerances for the manufacture of the seal 34 (and / or section 22) and the inner side wall 17 of the cylinder define a small gap 41 between these parts. The outer diameter of the seal 34 or plunger portion 22 is larger than the diameter D1 of the ratchet teeth, and in the embodiment shown in FIG. 7, the diameter of the seal 34 of the plunger is only slightly less than the diameter of the inner wall 17 of the cylinder. The seal of the plunger creates a barrier between the external environment and the ratchet teeth, so that between the seal 34 and the inner wall 17 of the cylindrical body 12 you cannot stick any foreign object. Thus, the seal 34 or the plunger portion 22 serves to prevent unauthorized access to the spring lock clip 40 and damage thereof. In another embodiment, the seal 34 is rubber and comes into direct contact with the inner side wall 17, while at least the seal portion is partially compressed by the inner wall.

 At the distal end of the plunger element 14 is a piston or sealing element 44 for displacing the liquid, which is preferably made of a rubber-like, partially compressible material. Such material is preferably synthetic rubber approved for use in medicine. And in this case, the piston 44 can either be molded or molded in one piece with the plunger, or made as a separate rubber part. As seen in FIG. 5,5a and 6-8, the piston can be attached to the distal end of the plunger with a blind hole tightly mounted on a protrusion in the form of a truncated cone, as shown in FIG. 7. This ensures that the rubber piston is firmly attached to the plunger. When the piston 44 is radially compressed, the diameter of the piston 44 is almost equal to the diameter of the inner side wall 17, which provides a sliding and simultaneously sealing contact between them. When the plunger element 14 moves distally inside the cylindrical body 12, all of the liquid located on the distal side of the piston 44 will pour out through the tip 18 and the needle 15. In addition, the sealing element 44 prevents the penetration of the drug or other liquid into the cavity located above it (from the proximal side of it). Obviously, the piston 44, mounted directly on the plunger element 14, moves with it.

 Near the proximal end of the piston 44 there is an expanded sealing portion 52 of the plunger portion, which, like the seal 34 or plunger portion 22, prevents unauthorized access to the ratchet teeth 28 and the spring lock clip 40. It also prevents penetration into the space located on the proximal side of the piston by paper clip, knife, etc. The diameter of part 52 is approximately equal to the inner diameter of the wall of the cylindrical body 12.

In FIG. 9, 10 and 11 show a locking spring 40 in detail. In a preferred embodiment, the spring, after giving it a basic shape, is a hollow hexagon with one side open. The final shape may be semi-cylindrical with a plunger span of about 200 ^° . The spring is preferably made of a thin piece of elastic metal, preferably of a single sheet of stainless steel of constant thickness. The specified material must have elasticity so that the spring can be opened for its initial installation on the selected ratchet tooth 30 (this is done by the manufacturer) and so that after installation on the plunger element, the locking spring 40 is compressed, taking its original size and shape. In addition, the resilience allows the spring locking clip 40 mounted in the cylinder on the plunger element to bend radially inward and outward. A blocking clamp is mounted on the plunger rod by pushing it with its open side onto the ratchet tooth, while temporarily squeezing the front walls 70 and 72 of the clamp. After the initial installation, the spring element cannot be displaced from the plunger, which is ensured by the ratio of the size of the open side of the clamp and the diameter D1 of the ratchet teeth of the plunger, which may be in the form of a truncated cone or beads.

In another embodiment, due to the small gap between the plunger and the inner side wall 17, in which the locking clip 40 is located, the fastening of this clip to the plunger is achieved even if it covers the plunger less than 180 ^o . The dimensions of the spring locking clip 40 are such that the distance between the edges of the front walls 70 and 72 is less than the diameter D1 of the ratchet teeth. In one embodiment, the locking clip 40 covers the plunger element 14 by at least 180 ^° , so that after installation, the clip cannot accidentally slide off the plunger element. In a preferred embodiment, the clamp reach of the plunger is about 200 ^° . In an alternative embodiment of the invention, when the design of the syringe allows for the delivery of 0.1 cm ^{3 of} medicine, the blocking clip may have a significantly smaller coverage around the circumference. It is established that the minimum plunger coverage is about 27 ^o .

 In a preferred embodiment, the height h of the spring locking clip 40 is less than the total width w after finalizing. In this case, the locking clip has the shape of a disc of small height. Compared to an elongated device, such a clamp is simpler and cheaper to manufacture, since it requires less material and high-speed processing equipment can be used. For clarity, in FIG. Figures 1 and 2 show that a locking clamp covers approximately 2 ratchet teeth. However, in practice, the height of the spring locking clip is assumed to be smaller.

The locking clip has a flat rear wall 60 and two opposing side walls 62 and 64 attached to the side edges of the rear wall and extending outward. From the edges 66 and 68 of the side walls 62 and 64, the front walls 70 and 72 extend respectively inward. Each of these walls 60, 62 and 64 has a rectangular shape. The front walls 70 and 72 have inclined edges 71 and 73, respectively (Fig. 9). The distance between the leading vertical edges 74 and 76 of the front walls 70 and 72, respectively, is less than the diameter D1 of the base 32 of the ratchet teeth 28. Therefore, during the assembly of the syringe, the spring locking clip 40 can be pulled apart and put on the selected ratchet tooth 30, while when the distance between the leading vertical edges 74 and 76 of the clamp, after the tooth is covered, it will become smaller than the diameter D1 of the base 32 of the tooth, the clamp will take its original dimensions due to elasticity. Due to this, accidental jumping of the clamp from the plunger element is eliminated and the clamp can only be removed by specifically applying force to it. In the above alternative embodiment of the invention, where the blocking clamp has a coverage of less than 180 ^° , and for syringes with a volume of 1 cm ³ that dispenses doses as small as 0.1 cm ³ , it reaches even 27 ^° , the blocking clamp cannot be removed the plunger after installation in the cylinder because the inner space of the cylinder is mainly occupied by the plunger and clamping and jumping off the clamp from the plunger is prevented by the inner side wall 17 of the cylinder.

 The rear wall 60 has an upper edge 78, from the middle of which the tab 80 extends upward. The tab 80 has an edge 82 designed to contact the outer edge of the base 32 of the ratchet tooth. The foot 80 is in the same plane with the rear wall 60. Due to contact with the edge of the ratchet teeth, the foot prevents the swing of the clamp on the plunger during the movement of the plunger and ensures their alignment. The foot prevents jamming and improves stability.

 The sliding teeth 83 and 85 extend upward from the front walls 70 and 72, respectively, oriented in the proximal direction and inward. A locking clip 40 mounted on the plunger hangs freely on the selected ratchet tooth, which may be in the form of a truncated cone or bead. During the stroke of the plunger corresponding to the dispensing of the drug, the sliding, inwardly inclined teeth provide movement of the clamp to the distal end. In particular, they come in contact with the base 32 of the ratchet tooth on which the clip hangs. When the plunger moves in the distal direction, it pushes the clamp in the same direction. To give the sliding teeth the required flexibility, the gaps 91 and 93 are used (see Fig. 9). The upper edges 87 and 89 of the teeth 83 and 85, respectively, first rest on the inclined surface 31 of the ratchet tooth or, if the teeth are made in the form of beads, on smooth spherical surfaces. When moving the plunger in the distal direction, the upper edges 87 and 89 will abut against the bottom of the ratchet tooth, so that the clamp will move on the plunger. However, when the plunger moves in the proximal direction, the elasticity of the clamp allows the teeth 83 and 85 to slide due to their radial flexibility on the inclined surfaces 31 or the convex surfaces of the ratchet teeth of the plunger when the spring locking clip is held in place by inserting the locking teeth 84,86,88 and 90 into the inner side wall 17 of the cylinder.

 When the plunger 14 moves in the distal direction, a blocking spring moves with it, since the base of the ratchet tooth pushes the upper edges 87 and 89 of the teeth 83 and 85. At the same time, the elasticity of the blocking clamp 40, which is held in place, allows the plunger to move proximally relative to him, since the teeth 83 and 85 will slide along the inclined or convex surfaces of 31 ratchet teeth.

 Blocking teeth 84.86.88 and 90 extend from the upper edge of the side walls 62 and 64 in the proximal direction and outward, with teeth 84 and 86 extending from the side wall 62, and teeth 88 and 90 from the side wall 64. Blocking teeth 84.86 , 88 and 90, crashing into the cylinder wall, are made in localized areas 95 and 97, enhancing the action of the teeth. To ensure the necessary flexibility of these sections 95 and 97, gaps 99 and 101 are provided. The blocking teeth have a triangular shape and sharp contact ends 105,107,109 and 111, which are offset outward from the outer flat surface of the side walls 62 and 64 and are in contact with the inner side wall 17 of the cylindrical case 12, leaning on it. The hardness of the contact sharp ends exceeds the hardness of the inner wall 17 of the cylindrical body 12, so when you try to move the blocking clamp 40 in the proximal direction using a plunger, these sharp ends will cut into the inner surface of the side wall of the cylindrical body, due to the radial elasticity of the spring blocking clamp in the outer direction. Thus, the sharp contact ends prevent the blocking clip from moving in the proximal direction. However, the locking clip can move in the distal direction, since the contact sharp ends are bent radially inward and when the plunger moves toward the distal end, they will slide along the inner side wall 17. The shape and elasticity of the locking clip allow the possibility of said folding in the radial direction. The distance between the contact sharp ends 105 or 107 and 109 or 111 may be less than the inner diameter of the side wall of the cylindrical body 12, but since these ends are offset outward from the outer flat surface of the side walls 62 and 64, all sharp ends can be counted into contact with the inner side wall 17 of the cylindrical body 12. The presence of several contact sharp ends ensures the insertion of the locking clip into the side wall 17 even taking into account changes in the inner diameter of the cylinder within accelerations for its manufacture.

 A semicircular tab 110 extends distally from the rear wall 60, which balances the tab 80 and also prevents the clamp from jamming when the plunger moves. The tab 110 is bent inward to the plunger, at or near the edge 112, and provides a smooth movement of the plunger and clamp in the distal direction without scratching the inner surface of the cylinder. When the plunger is completely moved in the distal direction, the tab 110 is practically stuck between the seal 52 of the plunger and the side wall 17, which further blocks the clamp in the distal position.

 The manufacture, assembly and operation of the device are as follows. The cylindrical housing 12 is made using the same technology and the same materials as for traditional medical syringes. The plunger element 14, including ratchet teeth in the form of beads or a truncated cone and seals 34, 52, is preferably molded from plastic as a single product. In a preferred embodiment, the plunger is molded from plastic with a brittle additive. A rubber piston 44 is attached to the plunger. The manufacturer sets the maximum dose for a given batch of syringes. To this end, he can either reduce the size of the syringe barrel to receive a given maximum dose and / or adjust the position of the spring blocking clamp on the plunger rod in a standard size syringe. Having determined the maximum dose, the blocking clamp 40 is mounted on the ratchet tooth 30 in accordance with this maximum dose. When molded, individual ratchet teeth can be stamped or marked with suitable marks to facilitate the installation of a blocking spring 40 on a specific ratchet tooth corresponding to a particular maximum dose value.

 The spring clip is installed by spreading the front walls 70 and 72 and sliding the vertical edges 74 and 76 around the circumference of the base 32. When placing the locking clip 40 closer to the distal end of the plunger element 14, a lower maximum dose for this syringe is provided than when placing the same clip closer to the proximal end. When installing the clamp, its edges 74 and 76 are moved apart so that the distance between them becomes equal to the diameter D1 of the base 32 of the ratchet tooth, which allows the radial elasticity of the spring clip. The clamp can now be slid onto the plunger. The clamp does not have a strong attachment to the plunger, its sliding teeth 83 and 85 only touch the inclined or convex surface 31 of the tooth, so that the locking clamp hangs on the ratchet tooth.

After the leading edges 74 and 76 of the clamp move along the circumference of the base of the ratchet tooth to the points located on the same diameter D1, these edges, due to the elasticity of the spring blocking clamp, return to their original position. Specialists in this field should be clear that the locking clip 40 is installed on the plunger element so that it can only be removed by applying physical force spreading to the sides of the edges 74 and 76. The locking clip is held on the plunger due to the plunger spanning more than 180 ^o and with the help of teeth 83 and 85, based on the inclined surface 31 of the ratchet tooth. The locking clamp does not compress the ratchet tooth, but is held loose on its inclined or convex surface. As indicated above, the upper edges 87 and 89 of the teeth 83 and 85 protrude or are bent inward so that they can touch the inclined or convex surface 31 of the ratchet tooth, resting on it.

 The proximal movement of the spring clip 40 relative to the plunger element 14 is blocked by the fact that the upper edges 87 and 89 of the sliding teeth 83 and 85 abut against the bottom of the base of the adjacent adjacent ratchet tooth. After installing the locking clamp in the desired position, the manufacturer completes the assembly process by placing the plunger element 14 together with the locking clamp 40 in a cylindrical body or cylinder. The elasticity of the spring allows you to insert the plunger and clamp into the cylinder. Then the product is packaged and delivered to the final consumer.

 In the embodiment shown in FIG. 13-33, the syringe plunger has a gap 114 for aspiration either between the disk-shaped element in contact with the thumb and the ratchet tooth, or between two ratchet teeth having the shape of a truncated cone or bead. The length of such a gap is determined by the manufacturer. The gap 114 allows the reciprocating movement of the plunger, i.e. movement in the proximal and reverse directions, for aspiration, without moving the blocking clip during distal movement of the plunger. As long as the locking clip is in the gap 114, it will not move, even if the plunger moves in both directions several times. The locking clamp will perform its “one-time” function only if the plunger is pulled in the proximal direction so that the locking clamp fits on the nearest distal ratchet tooth or on any of the following teeth. After that, as shown in FIG. 15 and 16, when the plunger moves in the distal direction, the blocking clip will move with it.

 In the embodiment shown in FIG. 1-12, the needle 15 is inserted into the vessel with the medicine and the disk 20 in contact with the thumb is moved in the proximal direction relative to the protrusion 26. When the plunger is pulled or moved in the proximal direction, the locking clip 40 will remain in the cylinder in one place, since the locking teeth of the clamp, being bent outward, cut into the side wall of the cylinder. The plunger can move in the proximal direction until the upper edge of the seal 52 comes into contact with the lower edge 112 of the locking clip 40. After this, further advancement of the plunger element 14 in the proximal direction is impossible, since the contact sharp ends 105,107,109 and 111 of the locking teeth 84, 86.88 and 90 are stuck in the inner side wall 17 of the cylindrical body 12.

 Those skilled in the art will appreciate that the locking clip 40 cannot move when the plunger element 14 moves in the proximal direction. Any proximal movement of the blocking clamp is prevented by sharp contact ends. The initial position of the blocking clamp and, accordingly, the blocking teeth 84,86,88 and 90 relative to the plunger determines the maximum stroke of the reciprocating movement of the plunger in the cylinder and, therefore, the maximum dose that can be administered by syringe. During the movement of the plunger in the proximal direction, the tabs 80 and 110 of the locking clamp slide along the edges of the ratchet teeth, keeping the clamp aligned with the cylinder and preventing it from jamming. The radial elasticity of the teeth of the spring blocking clamp 40 is such that when the plunger element 14 is pulled out of the cylindrical body 12 or moved proximal to it, the edges 87 and 89 will move along the inclined or spherical surface 31 of each ratchet tooth 30. Since the blocking clamp is held in place in the cylindrical housing 12 due to the interaction of the contact sharp ends 105,107,109 and 111 with the inner cylindrical surface 17 of the cylindrical housing 12, the plunger element 14 can draw lag until the sealing element 52 comes into contact with the lower edge 112 of the locking clip 40. After that, the movement of the plunger element 14 in the proximal direction is blocked mechanically, since when you try to push the plunger further, the contact sharp ends will cut even deeper into the inner side the wall 17 of the cylindrical housing 12. Thus, the stroke of the plunger element in the cylindrical housing is limited.

 After filling the cylindrical body 12 with the medicine, in particular the area between the piston 44 (or 109 in FIG. 13) and the tip 18, the user can use the syringe to inject the medicine through the needle 15. The user inserts the needle through the patient’s skin and presses the thumb on the disk 20 while the plunger element 14 moves in the distal direction and pushes the piston 44, which leads to the issuance of all the medicine through the tip 18 and the needle 15. Since the upper edges 87 and 89 of the sliding teeth 83 and 85 are in contact with the base 32 located above them xp Apogo tooth, this tooth during distal movement of the plunger element 14 will push the clamp 40 in the distal direction and it will bend radially inward and slide in the cylinder in the same direction. Contact sharp ends prevent the blocking spring from moving only in the proximal direction, and movement in the distal direction is allowed by sliding the contact sharp ends along the inner side wall and the elasticity of the blocking clip.

 After all the medicine is withdrawn from the syringe, the seal 52, located above the piston 44, abuts against the lower edge 112 of the locking clip. This is shown in FIG. 16 in an embodiment of the syringe, where aspiration is provided. The second reciprocating movement of the plunger element 14 relative to the cylindrical body 12 is blocked mechanically, because when you try to move the plunger in the proximal direction for the second time, the locking clip 40 (106 in Fig. 13-16) adjacent to the seal 52 will cut into the side wall 17 more precisely, the sharp contact ends 105,107,109 and 111 will be pressed into the inner surface of the side wall 17 of the cylindrical body 12. Thus, it should be obvious that the reciprocating movement for suction the drug into the syringe 10 is blocked, since the plunger element 14 cannot be re-moved in the proximal direction relative to the cylindrical body 12.

 To make the syringe 10 even more unsuitable for subsequent use, the user can bend or twist the disk 20, intended for contact with the thumb, along the plane 24 of the fault, separating it from the plunger. Without the disk 20, moving the plunger element in any direction becomes extremely difficult, even if it is assumed that the spring-loaded locking mechanism can be unlocked first. In addition, the torn disc 20 can serve as a means to limit the supply of syringes. So, for example, a certain number of such disks can be collected and returned to the manufacturer or distributor for exchange for the same number of new syringes. When conducting inventories and revisions, it is easier to use ragged and flat disks for accounting than large syringes.

 In FIG. 12 shows an alternative embodiment of the present invention, wherein the thumb-contacting disk has a tilted profile portion 120 and a second disk-shaped portion 122 with a tilted outer wall. Together, the two parts form on the plunger an annular covered part of the dovetail lock. The proximal end of the cylindrical body 12 adjacent to the finger protrusion 26 is provided with an inwardly annular edge 130 ending with a blocking protrusion 132. The lip 130 with the protrusion 132 form on the cylinder an annular female dovetail lock. Thanks to such a device, when the disk 20 is completely moved in the distal direction, the inclined outer wall 122 slides along the edge 130 until the blocking protrusion 132 extends beyond the second annular disk-shaped part 122, thereby preventing any attempt to move the plunger in the cylindrical housing 12 in any direction . It will be apparent to those skilled in the art that the smallest edge diameter 130, i.e. at the end of the locking protrusion 132, is smaller than the largest diameter of the surface of the edge 134, however, the elasticity of the cylinder and the slit at the proximal end allow the edge 134 to slide along the edge 130 until it is held by the locking protrusion 132.

 In yet another embodiment, measures are provided to prevent an attempt to unlock the syringe for reuse. After the first full stroke of the plunger in the distal direction, the blocking clamp cuts into the side wall of the syringe near seal 52. The external force required to pull the blocking clamp out of the cylinder wall exceeds the tensile strength of the plunger, so a second attempt to move it in the proximal direction will result in breaking the plunger into two parts, preferably immediately above the blocking clamp (see Figs. 4 and 17). To prevent the plunger from breaking in this place, a section with a reduced diameter is made above the sealing portion 52 of the plunger. In a preferred embodiment, a portion of the plunger having a smaller cross section is positioned so that a rupture occurs just above the proximal surface of the clamp. As shown in FIG. 6,7 and 8, the plunger is made with two or more sections 114 and 116 of a smaller cross-section, in which a gap may occur when moving it.

In FIG. 11 it is clearly seen that the radial elasticity of the blocking clamp and the force created by it violate the centering of the plunger along the axis of the cylinder. Due to this, syringes having a very small diameter and volume can still be provided with a locking clip to prevent reuse. It is only required that in all diametric sections of the cylinder the thickness of the metal between the plunger and the side wall of the cylinder be the same. Since the blocking clamp acts asymmetrically on the plunger, in an alternative embodiment of the invention, this clamp can be made so small that it covers the plunger about 27 ^o from 360 ^o . This allows you to get a disposable syringe with a locking mechanism having a very small capacity. The forces created by the locking teeth will deflect the plunger from a centered position.

 In FIG. 18 is a vertical sectional view similar to FIG. 13, but related to another embodiment of the invention. The ratchet teeth in the form of a truncated cone are replaced here with ratchet teeth in the form of beads. On the plunger there are two spaces 120 and 122 for aspiration, between which there is one ratchet tooth. At the distal end, gap 120 is bounded by a ratchet tooth. The diameter of the rod in the gap is smaller than the inner diameter of the clamp, so the rod can easily reciprocate relative to the clamp without moving the latter. Two gaps allow aspiration before each of the two strokes of the syringe, providing a set of drugs, i.e., the syringe can be used to dispense two partial doses, each of which is preceded by an aspiration cycle. In FIG. 18 the syringe is in the initial position, i.e. until the first suction cycle is completed and before the plunger is at least partially extended.

 In FIG. 19 is a vertical section similar to FIG. 18, on which the plunger is partially elongated first for aspiration and then for filling the cylinder with medicine. The plunger rod can reciprocate until the user consciously exerts a force that allows the plunger rod to be pulled out so that the locking clip passes over the first ratchet tooth 130 through it. During this stroke, medication must be drawn into the cylinder in the proximal direction. While the locking clamp is between the ratchet teeth, i.e. in the gap for aspiration, the plunger can move in both directions one or more times. After the plunger rod has been extended in the proximal direction so that the locking clip passes through the ratchet tooth 130, the movement of the rod in the distal direction will be accompanied by the delivery of medication and the movement of the locking clip in the same direction. In FIG. 20 shows a vertical section similar to FIG. 18, on which the plunger is elongated so that the first ratchet tooth located at the distal end of the gap 122 passes through the blocking clip. In this position, the medicine is drawn into the cylinder. In FIG. 21 shows a vertical section similar to FIG. 18, in which the plunger is shown after performing its first full stroke in the distal direction to dispense all the medicine that was in the cylinder. The spring-loaded locking clamp is biased towards the distal end of the syringe along with the plunger. As can be seen in the drawing, this clamp is now in the middle position between the distal and proximal ends of the syringe.

 In FIG. 22 shows a vertical section similar to FIG. 18, on which the plunger rod is pulled a second time for aspiration until the cylinder is filled with medicine. From this position, the plunger rod can be moved in the proximal and distal directions without moving the blocking clamp as long as it is in the gap 120 and has no contact with the base of the ratchet tooth. In FIG. 23 shows a vertical section similar to FIG. 18, in which the plunger rod is depicted while moving in the distal direction for dispensing medication. The spring locking clamp moves together with the stem due to the contact of the clamp with the ratchet tooth 132, more specifically, the portion of the clamp in contact with the ratchet tooth is under its base, so the movement of the rod in the distal direction leads to the movement of the clamp. In FIG. 24 shows a vertical section similar to FIG. 21, in which the plunger rod is completely moved to the distal position, in which all the medicine is removed from the cylinder and the spring locking clip is in the extreme distal position. Further extension of the plunger is prevented by the teeth of the spring blocking clamp, which cut into the inner wall of the syringe barrel.

 In FIG. 25 shows a vertical section similar to FIG. 17, in which the plunger rod is broken as a result of an attempt to further extend the plunger. The pulling force exceeded the strength of the plunger rod, which led to its fracture. The force with which the spring clip is stuck in the cylinder wall exceeds the pulling force. Stem rupture occurs in the fault plane.

 In FIG. 26 shows a plunger element with two large spaces and one small space for aspiration, comprising a piston for displacing the drug and a sealing piston. The plunger element is shown before the spring blocking clip is installed on its rod and before the plunger element itself is installed in the syringe barrel. In FIG. 27 shows a plunger having a sliding tube at the proximal end to facilitate axial sliding in the cylinder. In addition, a sliding tube blocks access to the inside of the cylinder to foreign objects. As can be seen in the drawing, the lower side of the disk in contact with the thumb is changed. In FIG. 28 shows a plunger with two spaces for aspiration, and FIG. 29 - a plunger with one gap and ratchet teeth in the form of beads. The last of these plungers can be used by the manufacturer to vary the volume of the syringe over a wide range with the same cylinder volume, in accordance with the position of the clamp relative to the ratchet teeth dispensing drugs. In FIG. 30 shows an embodiment of a plunger with three large spaces and one small space for aspiration. This plunger can be used to dispense four doses of the drug, and the set of each of these doses into the syringe barrel is preceded by the movement of the plunger to aspirate. In FIG. 31 shows a plunger corresponding to the plunger in FIG. 26, broken in the fault plane when the consumer tries to reuse the syringe after its first use, i.e. after issuing two doses of the drug, when the force exerted by the consumer exceeds the structural strength of the plunger. In this case, the force with which the spring clip is inserted into the side wall of the cylinder is greater than the strength of the plunger rod. In FIG. 32 also shows the plane or fault points of the plunger shown in FIG. 26. The plunger may have one break point or several break points, which further ensures that the syringe cannot be reused. The plunger will break at any of these points if, after dispensing the medicine, the user tries to pull the plunger with a force exceeding the strength of its structure. In FIG. 33 shows another embodiment of a plunger whose stock has three ratchet teeth.

 This description describes several embodiments of a disposable syringe assembly with a hypodermic needle. Although specific embodiments are contemplated by the invention, the description is illustrative and does not limit the invention. Various changes to the invention and various fields of its application are possible within the scope of the invention and its essence.

Claims (19)

 1. A disposable syringe comprising a hollow cylinder having an inner cylindrical side wall, a needle tip at the distal end of the cylinder and a proximal end opposite the specified end of the cylinder, where the needle tip is located, a cylindrical plunger rod having a longitudinal axis inside the specified cylinder for axial movement in the cylinder for suction into the cylinder and displacement of liquid from it through the specified tip for the needle, while the plunger rod has at least one ratchet tooth, protrudes from the cylinder at its proximal end and has a sealing piston at its distal end, near the specified end of the cylinder, where the needle tip is located, and a spring locking clip mounted on the plunger rod and having contact with a ratchet tooth and at least one outward oriented a blocking tooth with a contact sharp end, wherein the means of contact with the ratchet tooth is in mechanical contact with the plunger rod, and the contact sharp end is in frictional contact with the decree a side wall, characterized in that the spring blocking clamp is made in the form of a radially elastic spring blocking clamp with an open wall, the plunger rod has at least one gap for aspiration bounded by a smooth rod wall having a smaller diameter compared to the diameter of the ratchet tooth, and located proximally relative to the ratchet teeth, the plunger rod is made with the possibility of free reciprocating movement when the spring blocking clamp is in the gap for a pirations on the plunger rod, the spring locking clip is made to hold it in place in the cylinder due to frictional engagement of the contact sharp end with the specified side wall when moving the plunger rod, the means of contact with the ratchet tooth and the spring locking clip are made to interact when moving the plunger rod into in the proximal direction, which means that the ratchet contacting means will move the spring locking clip together with the plunger rod into the distal In this direction, the spring blocking clamp and the plunger rod are made so that by moving the plunger in the proximal direction, they allow the syringe to draw medicine into the cylinder volume, which is determined by the set position of the spring blocking clamp on the plunger rod, and the plunger rod is configured to displace the drug and move the spring blocking clamping inside the cylinder after reaching the contact of the spring blocking clamp with the ratchet tooth, but the plunger rod is displaced by the entire cylinder length There is frictional adhesion between the specified contact sharp end and the inner side wall of the cylinder.  2. The disposable syringe according to claim 1, characterized in that the means of contact with the ratchet tooth of the plunger rod contains a contact element oriented inward. 3. The disposable syringe according to claim 1, characterized in that the spring locking clip covers the plunger rod by an amount in the range of about 180 ^° to less than 360 ^° . 4. The disposable syringe according to claim 1, characterized in that the spring locking clip covers the plunger rod by less than about 180 ^o . 5. The disposable syringe according to claim 1, characterized in that the spring locking clip covers the plunger rod less than 180 ^o , and more than about 27 ^o . 6. The disposable syringe according to claim 1, characterized in that the volume of the cylinder filled with the medicine is determined by the initial position of the spring blocking clamp on the plunger rod and is about 0.1 cm ³ .  7. The disposable syringe according to claim 1, characterized in that the spring locking clip is configured to deflect during movement of the plunger from the axis of the hollow cylinder with the removal of it from a position coaxial with the hollow cylinder.  8. The disposable syringe according to claim 1, characterized in that each of the ratchet teeth has the shape of a truncated cone.  9. The disposable syringe according to claim 1, characterized in that each of the ratchet teeth has a bead shape.  10. The disposable syringe according to claim 1, characterized in that sealing means are installed on the distal and proximal ends of the plunger rod to create a sterile cavity filled with medicine and to prevent unauthorized access to the spring lock clip.  11. The disposable syringe according to claim 1, characterized in that the plunger rod has at least one fault plane, in which its tensile strength is less than the friction clutch between the contact sharp end of the spring blocking clamp and the side wall of the cylinder.  12. The disposable syringe according to claim 1, characterized in that the plunger rod has two or more gaps for suction, located along the axis at a distance from each other, and there is at least one ratchet tooth located distally relative to each gap for suction.  13. The disposable syringe according to claim 1, characterized in that the means of contact with the ratchet tooth is configured to bend radially outward along the surface of each ratchet tooth when the plunger rod moves in the proximal direction.  14. The disposable syringe according to claim 1, characterized in that the means of contact with the ratchet tooth is arranged to move with the plunger rod when it moves in the distal direction when it is in contact with the base of the ratchet tooth.  15. The disposable syringe according to claim 1, characterized in that said suction gap includes a portion of the plunger rod having a smaller diameter than the diameter of each of the ratchet teeth.  16. The disposable syringe according to claim 1, characterized in that the plunger rod has two or more gaps for aspiration, each of which is located between adjacent ratchet teeth of the rod.  17. The disposable syringe according to clause 16, wherein the spaces for aspiration have different lengths.  18. The disposable syringe according to claim 1, characterized in that it is arranged to stop performing a gap for aspirating its function when the plunger rod is moved in the proximal direction so that the spring locking clip is mechanically connected to the ratchet tooth of the rod.  19. The disposable syringe according to item 16, characterized in that it is configured to stop performing a gap for aspirating its function with each movement of the plunger rod in the proximal direction so that the spring locking clip is mechanically connected to the ratchet rod of the rod adjacent to this gap .

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