FLOW RATE REGULATOR FOR LIQUID MEDICINE OR BLOOD TRANSFUSION UNIT

Abstract: A flow rate regulator comprising a first cylindrical member (A), a second cylindrical member (C) and a disc-shaped member (B) to regulate a flow rate of liquid flowing through a transfusion unit. The liquid is introduced into the second cylindrical member (C) via an inlet port (11). It flows through the disc-shaped member (B) via a through hole (18) and flows further along a peripherally extending groove (21) in the first cylindrical member (A). Then, it is discharged from the first cylindrical member (A) via an outlet port (26) after a flow rate is regulated as required. The disc-shaped member (B) is fitted in the second cylindrical member (C) so as not to be rotated relative to the latter and the sub-assembly is fitted in the first cylindrical member (A). The peripherally extending groove is so designed that its cross-sectional area is gradually varied on the bottom portion (19) of the first cylindrical member (A). A position where the through hole (18) in the disc-shaped member (B) is communicated with the peripherally extending groove (21) in the first cylindrical member (A) is varied by rotating the first cylindrical member (A) so that a cross-sectional area of the peripherally extending groove (21) is varied correspondingly. This allow a flow rate of the liquid flowing through the regulator to be adjusted as required.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a flow rate regulator used for a liquid or blood transfusion unit to regulate a flow rate of liquid medicine or blood flowing therethrough. Further, the present invention relates to a liquid medicine or blood transfusion unit having the flow rate regulator used therefor. Description of the Related Art When a medical instrument such as liquid medicine or blood transfusion unit or the like is used, it is necessary to regulate a flow rate of liquid medicine or blood flowing through a tube. To this end, it is well known that flow rate regulating means is disposed midway of the tube. Many kinds of flow rate regulating means have been heretofore known. Among many conventional simple and inexpensive flow rate regulating means, typical one is designed in the form of a roller clamp. This roller clamp is constructed by a housing and a roller rotatably accommodated in the housing. A tube through which liquid medicine or blood flows is clamped between the housing having a suitable angle of inclination and the outer peripheral surface of the roller so that a flow rate of the liquid medicine or blood is regulated as required by properly varying a degree of clamping by displacing the roller toward or away from the housing. With the above roller clamp, it has been found that the throat portion of a tube is deformed as time elapses, causing a flow rate to be reduced gradually due to gradual reduction of the effective cross-sectional area of the tube. To obviate the foregoing problem, several improvements were tried. Among these improvements, the roller clamp including a housing of which bottom is formed with V-shaped grooves has been put in practical use. However, with respect to this improved roller clamp, it has been pointed out as a problem that a flow rate is substantially varied in the same manner as the conventional roller clamp under the influence of variation of the environmental temperature, although variation of the flow rate caused as time elapses has been reduced remarkably when the roller clamp is used at a constant temperature. Besides the aforementioned roller clamp, some of this kind of conventional flow rate regulating means are disclosed, e.g., in U.S. Patent Nos. 3,877,428, 4,428,397 and 4,769,012, in Japanese Laid-Open Patent NO. 247,470/1986, in DE-A-3 538 890 and in FR-A-2 153 360. Each of the conventional flow rate regulating means is constructed by combining and assembling a plurality of components together so as to allow a flow rate to be regulated by varying a cross-sectional area of the flowing passage. The respective flow rate regulating means disclosed in the above patents have drawbacks that they are complicated in structure and require a plurality of split molding dies for molding the components, resulting in a manufacturing cost, particularly an expenditure required for provision of the molding dies being increased. On the other hand, the conventional flow rate regulating means disclosed in the Japanese prior invention is constructed merely by two components. However, it has been found that the flow rate regulating means also has drawbacks that it has a narrow range of regulation of a flow rate and moreover it has a low accuracy of the same. In addition, US-A-3 323 774 discloses a flow rate regulator comprising two circularly shaped components which are rotatable with respect to each other so as to regulate the flow rate of a fluid by means of a peripheral groove having a gradually varying crossectional area, wherein two axially extending holes through both components are located on the same peripheral circle of said groove. With this configuration the fluid outlet is integral with the rotating component and radially displaced from the axis of the regulator. This causes a drawback of possible discomfort to the patient during adjustment of the regulator. Accordingly, it can be concluded that all the conventional flow rate regulating means have a practicability's defect. SUMMARY OF THE INVENTION The present invention has been made with the foregoing background in mind and its object resides in providing a flow rate regulator usable for a liquid medicine or blood transfusion unit which is entirely free from the drawbacks inherent to the flow rate regulating means mentioned above and assures that a flow rate is not significantly varied as time elapses and as the environmental temperature fluctuates. Other object of the present invention is to provide a flow rate regulator usable for a liquid medicine or blood transfusion unit which assures that a flow rate can be regulated at a high accuracy during a period of liquid medicine or blood transfusion. Another object of the present invention is to provide a flow rate regulator usable for a liquid medicine or blood transfusion unit which is simple in structure and can easily be manufactured at an inexpensive cost. To accomplish the above objects, the present invention provides a flow rate regulator as defined in claim 1. Preferred embodiments of the present invention, are defined in the dependent claims. Particularly, in a case where it is not necessary that the inlet port on the second cylindrical member and the outlet port on the first cylindrical member are arranged along the central axis of the flow rate regulator, the radially extending communication groove on the first cylindrical member and the radially extending communication groove on the disc-shaped member are not required any longer. The peripherally extending groove in the first cylindrical member has an interrupted part so that flowing of the liquid medicine or blood through the regulator is interrupted as long as the through hole in the disc-shaped member is located within the range of the interrupted part. The first cylindrical member, the second cylindrical member and the disc-shaped member are molded of plastic material, respectively. To assure that the disc-shaped member is normally brought in close contact with the bottom portion of the first cylindrical member, it is preferable that the disc-shaped member is molded of plastic material having higher elasticity than that of plastic material employed for the first cylindrical member and the second cylindrical member. Further, the present invention provides a liquid medicine or blood transfusion unit having the aforementioned flow rate regulator used therefor. To remove fine foreign materials in liquid medicine or blood, it is preferable that a filter is disposed upstream of the flow rate regulator. These and other objects, features and advantages of the present invention will be readily apparent from reading of the following description which has been made with reference to the accompanying drawings. The present invention will be illustrated in the following drawings in which: Fig. 1 is a sectional view taken along the axis line of a flow rate regulator in accordance with an embodiment of the present invention. Fig. 2 is a perspective view of the flowing rate regulator in Fig. 1, shown in a disassembled state. Fig. 3 is a plan view of a first cylindrical member constituting the flowing rate regulator of the present invention, and Fig. 4 is a sectional view of the first cylindrical member taken in line a - a′ in Fig. 3. Now, the present invention will be described in a greater detail hereinafter with reference to the accompanying drawings which illustrate a preferred embodiment thereof. A flow rate regulator in accordance with the present invention is substantially constituted by a first cylindrical member A, a disc-shaped member B and a second cylindrical member C. Specifically, the first cylindrical member A has a bottom portion 19 which is formed with a peripherally extending groove 21 of which cross-section exhibits a V-shaped contour. As is best seen in Fig. 3, the groove 21 has a width and a depth both of which is gradually increased from a start point 25 to an end point 24. With this construction, the groove 21 has a cross-sectional area which is increased gradually. The groove 21 is communicated with a radially extending groove 23 on the bottom portion 19 via the end point 24 having the largest cross-sectional area. The groove 23 has the same cross-sectional area as that of the groove 21 or a cross-sectional area more than that of the same. As is apparent from the drawing, the groove 23 extends toward the center of the bottom portion 19 until it is communicated with a through hole 20 in the first cylindrical member A. The disc-shaped member B has also a through hole 18 formed therein which is communicated with the groove 21 when the disc-shaped member B is assembled in the first cylindrical member A. With such construction, liquid medicine or blood to be transfused (hereinafter referred to simply as liquid) is first caused to flow in the narrow part of the groove 21 via the through hole 18 in the disc-shaped member B and thereafter it flows further therefrom to the wide part of the groove 21. Accordingly, the start point 25 of the groove 21 which is communicated with the through hole 18 in the disc-shaped member B defines the smallest cross-sectional area along the whole flow passage of the liquid so that the smallest flow rate is determined by the start point 25 of the groove 21. As the through hole 18 comes near to the end point 24 of the groove 21 by rotating the first cylindrical member A with an operator's hand, the flow rate is increased more and more. On the contrary, as the through hole 18 comes near to the start point 25, the flow rate is reduced more and more. In this connection, it should be noted that flowing of the liquid is interrupted as long as the through hole 18 is located at a region on the bottom portion 19 where no groove is formed in the first cylindrical member A, as is best seen in Fig. 3. The disc-shaped member B is formed with a radially extending groove 17 on the upper surface thereof which extends from the through hole 18 to the center of the second cylindrical member B. In addition, as is apparent from Fig. 2, the disc-shaped member B is formed with a cutout 16 on the upper surface. The second cylindrical member C has a through hole 15 formed at the center of a bottom portion 13, and a protrusion 12 is provided inside of the second cylindrical member C at a position corresponding to the cutout 16 on the disc-shaped member B. The protrusion 12 on the second cylindrical member C and the cutout 16 on the disc-shaped member B are provided to assure that member B and the member C are not rotated relative to each other. It should of course be understood that the present invention should not be limited only to the foregoing provision for the purpose of inhibiting the members B and C from being rotated relative to each other. Other relative rotation inhibiting means may be employed for the same purpose, if it is proven that it functions satisfactorily. Three members A, B and C as constructed in the above-described manner are assembled together in such a manner that the member B is first fitted inside of the member C and the sub-assembly is then fitted inside of the member A. In the illustrated embodiment, the member A is provided with an annular protrusion 22 round the inner wall surface and the member C is formed with an annular groove 14 round the outer wall surface so that both the members A and C are rotatably assembled together by fitting the protrusion 22 in the groove 14. Incidentally, a positional relationship of the annular protrusion 22 relative to the annular groove 14 should be so set that the member B is brought in close contact with the bottom surface of the member A in the presence of the member C. To this end, it is preferable that elastomeric material such as plasticizable polyvinyl chloride, polyurethane, silicone rubber or the like is employed for the member B rather than hard plastic material. Next, operations of the flow rate regulator as constructed in the aforementioned manner will be described below. A liquid is introduced into the interior of the member C via an inlet port 11 and the through hole 15. It flows through the groove 17 and the through hole 18 in the member C and further flows through the grooves 21 and 23 on the member A until it is discharged from an outlet port 26. Regulating of a flow rate is achieved by rotating the member C relative to the member A and vice versa. As the member C is rotated along with the member B, a positional relationship of the through hole 18 in the member B relative to the groove 21 on the bottom portion of the member A is varied so that the cross-sectional area of the groove 21 is varied correspondingly. This makes it possible to regulate the flow rate to a required value. If both the members A and C are calibrated in a suitable manner, calibrations prepared on them can be used as a measure for setting a flow rate as required. In the foregoing embodiment, both the grooves 17 and 23 are formed in order to assure that the inlet port 11 and the outlet port 26 are located along the axis line of the flow rate regulator of the present invention. If the inlet port 11 and the through hole 15 in the member C may be located in alignment with the through hole 18 in the member B and the outlet port 26 and the through hole 20 in the member A may be located in alignment with the start point 25 of the groove 23, both the grooves 17 and 23 will not be required. It should be noted that a manner of fitting the member A onto the member C should not be limited only to the aforementioned arrangement. Other type of arrangement may be employed, if it is proven that it is acceptable. Generally, a liquid medicine transfusion unit or blood transfusion unit is constituted by a bottle needle, a drip chamber, a vein needle and a tube connected to the latter. Preferably, the flow rate regulator of the present invention is incorporated in the upper part or the lower part of the drip chamber. The regulator may be united with the drip chamber. Alternatively, the regulator may be disposed midway of a liquid medicine or blood transfusion line. Since a flow rate is varied when the flow rate regulating part of the regulator is clogged with some foreign material, it is preferable that a filter is disposed upstream of the regulator. Particularly, in a case of the liquid medicine transfusion unit, it is essential that a filter is provided for the unit, because there is a danger that fine particles are introduced into liquid medicine after the bottle needle is penetrated through a rubber cap on the bottle and thereby a part of the rubber cap is cut off. To prevent any foreign material from being introduced into the body of a patient, a filter is often incorporated in the liquid medicine or blood transfusion unit. Provision of the filter in that way makes it possible to reduce the number of components for the transfusion unit. It is preferable that pores in the filter have a diameter in the range of 0.1 to 30 microns. To facilitate understanding of properties of the flow rate regulator in accordance with the present invention, an additional description will be made in accordance with results derived from tests conducted using the regulator. The members A and C were molded of ABS resin and the member was molded of plasticizable polyvinyl chloride. These members were assembled together in the above-mentioned manner to provide a flow rate regulator. The regulator was incorporated in a liquid medicine transfusion unit. How far a flow rate was varied as time elapsed was observed while water having a temperature varied within the range of 5 °C to 40 °C was caused to flow through the transfusion unit under a differential height of 65 cm. For the purpose of making a comparison, similar tests were conducted using a roller clamp which was widely used as a roller clamp having a reduced amount of fluctuation in flow rate. The roller clamp used for the tests included a roller which had a V-shaped groove formed thereon. Results derived from the tests are as shown in Table 1. flow rate in milliliter per minute environmental temperature 20.5 °C 5.8 °C 39.0 ° 9.8 °C present invention 44.8 34.2 49.2 30.8 compared example 40.6 24.0 151.8 68.2 As will be readily apparent from Table 1, the flow rate regulator of the present invention exhibits few fluctuation in flow rate irrespective of variation of the environmental temperature. In contrast with the regulator of the present invention, the conventional clamp roller exhibits a large amount of fluctuation in flow rate in response to variation of the environmental temperature. It will be readily understood that a flow rate can be maintained in a very stable state by disposing a filter upstream of the flow rate regulator. While the present invention has been described above with respect to a preferred embodiment thereof, it should of course be understood that it should not be limited only to it but various changes or modifications may be made without departure from the scope of the present invention as defined by the appended claims.

Claims: A flow rate regulator usable for a liquid medicine or blood transfusion unit comprising; a first cylindrical member (A) including a bottom portion, said first cylindrical member being formed with a peripherally extending groove (21) on said bottom portion of which cross-sectional area is varied gradually, said peripherally extending groove being communicated with an outlet port via a through hole (20) in the first cylindrical member, a second cylindrical member (C) including a bottom portion to be rotatably fitted in the first cylindrical member, said second cylindrical member having a through hole (15) formed therein which is communicated with an inlet port, and a disc-shaped member (B) adapted to be fitted in the second cylindrical member so as not to be rotated relative to the latter, said disc-shaped member being brought in close contact with the bottom portion of the first cylindrical member and having a through hole (18) formed therein which is communicated with the peripherally extending groove (21) on the bottom portion of the first cylindrical member as well as with the through hole (15) in the second cylindrical member, wherein a radially extending groove (23) by way of which one end of the peripherally extending groove (21) on the bottom portion of the first cylindrical member (A) is communicated with the through hole (20) in the first cylindrical member (A) is formed on the bottom portion of the first cylindrical member, and wherein a radially extending groove (17) by way of which the through hole (18) in the disc-shaped member is communicated with the through hole (15) in the second cylindrical member is formed on the opposite surface of the disc-shaped member to the peripherally extending groove (21) on the bottom portion of the first cylindrical member. The flow rate regulator as claimed in claim 1, wherein the peripherally extending groove (21) in the first cylindrical member has an interrupted part which prevents a liquid from flowing therethrough as long as the through hole in the disc-shaped member is located within the range of said interrupted part. The flow rate regulator as claimed in claim 1 or 2, wherein the first cylindrical member (A) is provided with an annular protrusion (22) round the inner wall surface and the disc-shaped member is formed with an annular groove round the outer wall surface so that the second cylindrical member is rotatably fitted in the first cylindrical member, said annular protrusion being fitted in said annular groove. The flow rate regulator as claimed in any of claims 1-3, wherein the disc-shaped member (B) is formed with a cutout and the second cylindrical member is provided with a protrusion in correspondence to said cutout so that the disc-shaped member is fitted in the second cylindrical member so as not to be rotated relative to the latter, said protrusion being brought in engagement with said cutout. The flow rate regulator as claimed in any of claims 1-4, wherein the first cylindrical member (A), the second cylindrical member (C) and the disc-shaped member (B) are molded of plastic material, respectively, and the disc-shaped member is molded of plastic material of which elasticity is determined higher than that of plastic material used for molding the first cylindrical member and the second cylindrical member so that the disc-shaped member is brought in close contact with the bottom portion of the first cylindrical member. A liquid medicine or blood transfusion unit using the flow rate regulator as defined in claims 1 to 5, wherein the flow rate regulator is incorporated in said transfusion unit. A liquid medicine or blood transfusion unit using the flow rate regulator as defined in claims 1 to 5, wherein a filter is disposed upstream of the flow rate regulator.

Inventors: KAWAI, TATSUYA, MATSUDA, TAKASHI
Applicants: JAPAN MEDICAL SUPPLY CO., LTD.
Application year: 1989
Main classification: A61M5
IPC codes: A61M5