Multi-stage type flow rate switching device

Abstract: A multi-stage type flow rate switching device is provided which simplifies switching of flow paths and which rarely causes erroneous operation. The multi-stage type flow rate switching device includes a constant flow rate path 2 and a variable flow rate path 3 arranged in parallel between a liquid medicine flow inlet port 1 and a liquid medicine flow outlet port 4 where the variable flow rate path 3 can change the flow rate by means of a three-way stopcock 33. Although the flow rate can be switched in four stages when one variable flow rate path 3 is arranged as shown by Fig. 1, the flow rate can be switched in further multi-stages by providing two or more of the variable flow rate paths 3 .

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates to a multi-stage type flow rate switching device comprising a liquid medicine flow inlet port; a liquid medicine flow outlet port; a constant flow rate path and at least one variable flow rate path connected to and arranged in parallel between said liquid medicine flow inlet port and said liquid medicine flow outlet port; and a three-way stopcock provided in said at least one variable flow rate path for changing the flow rate of a liquid medicine through said device. More particularly, the invention relates to a multi stage type flow rate switching device capable of switching a liquid flow rate in multi stages, particularly capable of switching the flow rate of a liquid medicine in several stages by using a three-way stopcock. The multi-stage type flow rate switching device according to the present invention is preferably used by being connected to a ballooned liquid medicine continuous injector, an injector where liquid medicine is filled in a balloon made of an elastic rubber material and liquid medicine is continuously injected over a period of many hours into blood vessels or the like by utilizing the force produced by contraction of the balloon as disclosed in, for example, Japanese Examined Patent Publication No. JP-B-6-83725 corresponding to EP 0 464 761 B1. Such injector is used as a means for continuously administering a liquid analgetic, anesthetic, antibiotic, or carcinostatic agent into blood vessels, hypodermic portions, epidural portions or the like in a small amount. 2. Description of Related Art: A three-way stopcock has conventionally been used in the medical field when a blood transfusion or a solution transfusion is carried out. A three-way stopcock is typically constituted by a cylindrical portion having three branch tubes projecting in a T-like shape at the outer periphery of the cylindrical portion, a plug portion inserted in and rotatably attached to the cylindrical portion and having a liquid path in a T-like shape corresponding to the branch tubes of the cylindrical portion, and a lever attached to the plug portion for switching the flow paths. Meanwhile, with respect to a variable small flow rate control device used in a ballooned liquid medicine continuous injector, a device comprising flow rate control tubes connected to a multi-way stopcock has already been proposed (Japanese Unexamined Patent Publication No. JP-A-5-84310). The device is constituted by a main body having a cylindrical valve chamber where one flow inlet port and at least three flow outlet ports are formed.A plug having a cylindrical valve portion is rotatably inserted into the valve chamber of the main body. A slit opened in a fan-like shape and slender holes in a straight tube shape extending opposedly in the radial direction from the base of the slit, are formed in the valve portion and, even if the slender holes of the valve portion are connected to any of the flow outlet ports, the slit is connected to the flow inlet port. However, according to the above-described flow rate control device, one flow rate control tube is necessary for each flow outlet port and various sizes of the flow rate control tubes are necessary. It is troublesome in view of production control and assembly operation to fabricate various sizes of flow rate control tubes and integrate them simultaneously. Also, the use thereof involves a drawback where the switch angle of the lever is decreased for a large number of switchings and the display is complicated whereby erroneous operation is liable to occur. Additionally, US-A-4 237 879 discloses a multi-stage type flow rate switching device of the type mentioned in the beginning, comprising a liquid medicine flow inlet port; a liquid medicine flow outlet port; a constant flow rate path and at least one variable flow rate path connected to and arranged in parallel between said liquid medicine flow inlet port and said liquid medicine flow outlet port; and a three-way stopcock provided in said at least one variable flow rate path for changing the flow rate of a liquid medicine through said device. In said device, a first fluid flow can be established through the constant flow rate path if the three-way stopcock is in a first position, and a second fluid flow can be established in parallel through constant flow rate path and variable flow rate path, respectively, if the three-way stocock is in a second position. Since the flow control in one of the lines of the variable flow rate path can be adjusted, a variable flow rate can be established dependent on the position of the three-way stopcock. Furthermore, US-A-5 356 379 discloses a multi-stage type flow switching device comprising the features mentioned in the beginning with the exception of a three-way stopcock. Instead a clamp is arranged in the variable flow rate path. The present invention has been achieved as a result of an intensive study in view of the above-described situation and it is an object of the present invention to provide a multi stage type flow rate switching device which simplifies switching of flow paths and rarely causes erroneous operation. SUMMARY OF THE INVENTION The inventors have determined as a result of an intensive study that flow rate switching operations can be facilitated and erroneous operation can be prevented by a multi-stage type flow rate switching device of the type mentioned in the beginning which is characterized in that the liquid medicine flow outlet port is branched into three branch paths, one of the branch paths and the two remaining branch paths are respectively connected to the constant flow rate path and the variable flow rate path and flow rate control tubes that control the flow rate of said liquid medicine by flow resistance are arranged in the constant flow rate path and the variable flow rate path. The constant flow rate path and the variable flow rate path may preferably be accommodated in a housing having a liquid medicine flow inlet port and a liquid medicine flow outlet port at both ends thereof. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing an embodiment of the present invention; Fig. 2 is a plane view showing an embodiment of the multi-stage type flow rate switching device of present invention; and Fig. 3 illustrates an example of a liquid transfusion line integrated with a multi stage type flow rate switching device of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention are explained below with reference to the drawings. As shown by Fig. 1, a multi-stage flow rate switching device of the present invention includes a constant flow rate path 2 and a variable flow rate path 3. The paths are arranged in parallel between a liquid medicine flow outlet port 1 and a liquid medicine flow inlet port 4 and the flow rate of the variable flow rate path 3 can be changed by a three-way stopcock 33. Although the flow rate can be switched in four stages when one variable flow rate path 3 is arranged as shown by Fig. 1, the flow rate can be switched in further multi stages by providing two or more of the variable flow rate paths 3 as necessary. In the multi-stage flow rate switching device shown by Fig. 1, the liquid medicine flow outlet port 1 is branched into three branch paths 11, 12 and 13 and the liquid medicine flow inlet port 4 is branched into two branch paths 41 and 42. The constant flow rate path 2 is connected between the first branch path 11 of the liquid medicine flow outlet port 1 and the first branch path 41 of the liquid medicine flow inlet port 4. The variable flow rate path 3 is connected between the second branch path 12 and the third branch path 13 of the liquid medicine flow outlet port 1 and the second branch path 42 of the liquid medicine flow inlet port 4. The constant flow rate path 2 includes a flow rate control tube for controlling the flow rate by flow resistance. The entirety of the constant flow rate path 2 may be constituted by a flow rate control tube. The variable flow rate path 3 is constituted by the three-way stopcock 33, flow rate control tubes 31 and 32 respectively connected to the second branch path 12 and the third branch path 13 of the liquid medicine flow outlet port 1 and the three-way stopcock 33, and a connection tube 34 connected to the three-way stop cock 33 and the second branch path 42 of the liquid medicine flow inlet port 4 such that the flow rate can be varied by the three-way stopcock 33. The multi-stage type flow rate switching device may be constituted such that the device is accommodated in a housing 5 having a hole 51 for exposing a lever 331 of the three-way stopcock 33 as shown in Fig. 2. An explanation will be given of setting of flow rates as follows. Two or more of the variable flow rate paths 3 may be assembled in parallel between a liquid medicine flow outlet port 1 and a liquid medicine flow inlet port 4 in the multi-stage type flow rate switching device. For example, although the flow rate can be switched in four stages when one variable flow rate path 3 is provided, the flow rate can be switched in sixteen stages when two of the variable flow rate paths 3 are provided. Specifically, when the flow rates of the constant flow rate path 2 and the flow rate control tubes 31 and 32 of the variable flow rate path 3 in Fig.1 are respectively set to, for example, 1 ml/hr, 1 ml/hr and 2 ml/hr, the flow rates can be set to four stages of 1 ml/hr, 2 ml/hr, 3 ml/hr and 4 ml/hr. When two of the variable flow rate paths are arranged, the flow rates can be set in sixteen stages of 1 ml/hr through 16 ml/hr by setting the flow rates of the second variable flow rate path of the two flow rate control tubes respectively to 4 ml/hr and 8 ml/hr. The multi-stage type flow rate switching device of the present invention is mainly used by being combined with a liquid transfusion line as shown in Fig. 3. In Fig. 3, notation E designates the multi-stage type flow rate switching device, notation C designates a clamp, numerals 6 and 7 designate connection tubes and numerals 8 and 9 designate connectors. In using the liquid transfusion line, the connector 8 on the upstream side is connected to a liquid medicine injecting device, not shown, which utilizes the elastic force of a balloon, and the connector 9 on the downstream side is connected to a retaining needle, not shown. The clamp C is initially closed. When the clamp C is detached after setting the flow rate by operating the lever 331, a liquid medicine can be injected into blood vessels of a patient. As apparent from the above-described explanation, the following effects can be achieved by adopting the flow rate control device of the present invention. (1) Switching of the various flow rates is possible with the use of turning angles of 90° using combinations of the flow rate control tubes and the three-way stopcock and accordingly, a flow path switching operation is simplified and erroneous operation rarely occurs when a flow rate display is indicated on the housing. (2) The three-way stopcock is accommodated in a housing and, accordingly, the flow path can not be switched by accident such as dropping or pressing of the flow rate switching device or the like.

Claims: A multi-stage type flow rate switching device (E) comprising a liquid medicine flow inlet port (4); a liquid medicine flow outlet port (1); a constant flow rate path (2) and at least one variable flow rate path (3) connected to and arranged in parallel between said liquid medicine flow inlet port (4) and said liquid medicine flow outlet port (1); and a three-way stopcock (33) provided in said at least one variable flow rate path (3) for changing the flow rate of a liquid medicine through said device (E), characterized in that the liquid medicine flow outlet port (1) is branched into three branch paths (11, 12, 13), one (11) of the branch paths (11, 12, 13) and the two remaining branch paths (12, 13) are respectively connected to the constant flow rate path (2) and the variable flow rate path (3) and flow rate control tubes (2, 31, 32) that control the flow rate of said liquid medicine by flow resistance are arranged in the constant flow rate path (2) and the variable flow rate path (3). The multi-stage type flow rate switching device (E) according to claim 1, characterized in that the constant flow rate path (2) and the variable flow rate path (3) are accommodated in a housing (5) having a liquid medicine flow inlet port (4) and a liquid medicine flow outlet port (1) at both ends thereof.

Inventors: HIEJIMA KATSUHIRO, NAOKI YOSUKE, HIEJIMA, KATSUHIRO, NAOKI, YOSUKE
Applicants: NIPRO CORP, NIPRO CORPORATION
Application year: 1997
Main classification: A61M5
IPC codes: A61M39, A61M5