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 liquid medicine flow inlet port 1 having branch paths 11, 12 and 13 on a downstream side, a liquid medicine flow outlet port 2 having branch paths 21, 22 and 23 on an upstream side and constant flow rate paths 31, 32 and 33 for connecting respectively of the branch paths, and they are arranged in a housing 4 comprising a lid 41 and a housing main body 42. In the housing 4, there is provided clamping means 5 capable of selectively blocking the constant flow rate paths 31, 32 and 33.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates to a multi stage type flow rate switching device. More particularly, the present invention relates to a multi stage type flow rate switching device suitable for controlling variably a small flow rate 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 a human body by utilizing the force produced by contraction of the balloon) that 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 multi stage type flow switching device, as described in the preamble of claim 1, is disclosed in US-A-5 318 515. 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 a radial direction from the base of the slit, are formed at 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. 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 production steps, which can be fabricated at a low cost and which simplifies switching of flow path and rarely causes erroneous operation. SUMMARY OF THE INVENTION According to the present invention, there is provided a multi stage type flow rate switching device including a liquid medicine flow inlet port having plural of branch paths on a downstream side, a liquid medicine flow outlet port having plural branch paths on an upstream side, constant flow rate paths for connecting the plural branch paths of the liquid medicine flow inlet port and the plural branch paths of the liquid medicine flow outlet port, and a housing comprising a lid and a main body and capable of accommodating and arranging the plural constant flow rate paths. In the housing, there is provided clamping means which is capable of selectively blocking the plural constant flow rate paths. The clamping means of the present invention is constituted by plural plate-like members having engaging means for engaging with the housing and insertable from a slit provided at the lid of the housing. The plate-like members are stepwisely provided constant flow rate path blocking portions and constant flow rate path nonblocking portions, the constant flow rate path blocking portions being thicker than the constant flow rate path nonblocking portions. A desired flow rate can be selected by utilizing several kinds of the plate-like members each having a different stepped shape. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an explanatory view showing a multi stage type flow rate switching device according to the present invention (showing a state where a lid of a housing is closed); Fig. 2 is a plane view showing essential portions of the multi stage type flow rate switching device shown by Fig. 1 (showing a state where the lid of the housing is opened); Fig. 3 is a sectional view taken along a line VIII-VIII of the multi stage type flow rate switching device shown by Fig. 1; Fig. 4 is a sectional view taken along a line IX-IX of the multi stage type flow rate switching device shown by Fig. 1; Figs. 5(a), 5(b), 5(c), 5(d), 5(e) and 5(f) are explanatory views showing inserting operation of plate-like members used in the multi stage type flow rate switching device shown by Fig. 1; and Fig. 6 is an explanatory view showing detaching operation of the plate-like member that is inserted in Figs. 5(a), 5(b), 5(c), 5(d), 5(e) and 5(f). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention are explained below with reference to the drawings. Fig. 1 is an explanatory view showing the multi stage type flow rate switching device of the present invention (showing a state where a lid of a housing is closed), Fig. 2 is a plane view showing essential portions of the multi stage type flow rate switching device shown by Fig. 1 (showing a state where the lid of the housing is opened), Fig. 3 is a sectional view taken from a line VIII-VIII of the multi stage type flow rate switching device shown by Fig. 1 and Fig. 4 is a sectional view taken from a line IX-IX of the multi stage type flow rate switching device shown by Fig. 1. As shown by Fig. 2, a multi stage type flow rate switching device of the present invention includes a liquid medicine flow inlet port 1 having three branch paths 11, 12 and 13 on a downstream side, a liquid medicine flow outlet port 2 having three branch paths 21, 22 and 23 on an upstream side, and a flow rate control unit where constant flow rate paths 31, 32 and 33 for connecting respectively of the branch paths 11, 12 and 13 and the branch paths 21, 22 and 23, and they are accommodated and arranged in a housing 4 having an openable and closable lid 41. As shown by Fig. 1, tubes 81 and 82 are respectively attached to the liquid medicine flow inlet port 1 and the liquid medicine flow outlet port 2, and connectors 91 and 92 are respectively provided at another ends of the tubes 81 and 82. Here, the constant flow rate paths 31, 32 and 33 may be connected to the branch paths 11, 12 and 13 or the branch paths 21, 22 and 23 respectively through connection tubes 61, 62 and 63 which can be pressed and blocked by being pressed by a clamping means 5. Although according to the embodiment the constant flow rate paths 31, 32 and 33 are connected to the branch paths 21, 22 and 23 of the liquid medicine flow outlet port 2 through the connection tubes 61, 62 and 63, the connection tubes 61, 62 and 63 may integrally be formed with the branch paths 11, 12 and 13 of the liquid medicine flow inlet port 1 or the branch paths 21, 22 and 23 of the liquid medicine flow outlet port 2. Although the constant flow rate paths 31, 32 and 33 may be set to the same flow rate, it is preferable to set them to the different flow rates if combinations of switchings of flow rates are intended to increase in number. According to the embodiment, the flow rates are made to differ from each other by changing lengths of the constant flow rate paths 31, 32 and 33. A number of the constant flow rate paths in the present invention is not limited to three but the number may be increased or decreased as necessary. The housing 4 comprises the lid 41 and a housing main body 42, and the lid 41 and the housing main body 42 are openable and closable by mutual engaging means. Incidentally, a locking means may be provided to the housing 4 so that a patient cannot open or close it easily. It is preferable that grooves 431 and 432 or the like are provided to the housing 4 so that the liquid medicine flow inlet port 1, the liquid medicine flow outlet port 2 and the constant flow rate paths 31, 32 and 33 are fixed in the housing 4. As show by Fig. 1, a plate-like member inserting portion 412 capable of inserting the plate-like members 7 is provided at the lid 41 of the housing 4. Although the position of the plate-like member inserting portion 412 is not particularly limited so far as it is a position where the plate-like members 7 can block the constant flow rate paths 31, 32 and 33 (or the connection tubes 61, 62 and 63), when the liquid medicine flow inlet port 1 and the liquid medicine flow outlet port 2 are fixed to the housing 4 as in the embodiment, the plate-like member inserting portion 412 is preferably provided in a proximity of the liquid medicine flow inlet port 1 or the liquid medicine flow outlet port 2. In this case, it is preferable that the constant flow rate paths 31, 32 and 33 are connected to the liquid medicine flow inlet port 1 or the liquid medicine flow outlet port 2 through the connection tubes 61, 62 and 63, where the plate-like members 7 block the connection tubes 61, 62 and 63. A single or plural of constant flow rate path blocking portions each having a relatively thick wall and a single or plural constant flow rate path nonblocking portions each having a relatively thin wall are stepwisely formed at each of the plate-like.members 7. The flow rate is determined by selecting one of the plate-like members 7 in compliance with a desired flow rate from several kinds of the plate-like members 7 each having a different stepped shape. Further, the plate-like member 7 is provided with a pair of engaging arms 71 and hooks 711 respectively formed at external sides of the side walls at front end portions of engaging arms 71. Engaging holes 421 for engaging with the engaging arms 71 of the plate-like member 7 are formed at the housing main body 42 whereby the engaging hole 421 are engaged with the hooks 711 of the engaging arms 71 when the plate-like member 7 is inserted. The engaging arm 71 can easily be bent toward the inner side because of the flexibility of the material forming the engaging arm 71. The engaging state can be released by bending the engaging arm 71 toward the inner side. Here, it is preferable that the vicinity of the engaging holes 421 of the housing main body 42 is formed in a shape recessed inwardly toward the housing 4 where fingers may be put therein. Thereby, the engagement of the engaging arms 71 and the engaging hole 421 is not released erroneously when the plate-like member 7 is inserted into the engaging holes 421 as shown by Fig. 5 and Fig. 6. Further, the plate-like member 7 is preferably provided with a thickness whereby the plate-like member 7 is inserted into the plate-like member inserting portion 412 to a degree whereby the plate-like member 7 is not projected from the plate-like member inserting portion 412. Incidentally, the engaging means is not limited to the shapes of the engaging arm 71 and the engaging hole 421 in this embodiment. The multi stage type flow rate switching device of the invention can switch the flow rate in eight kinds of flow rates since the device has the three constant flow rate paths 31, 32 and 33. In this case, the plate-like member 7 can be used by turning leftside rightword. Accordingly, five kinds of plate-like members 7A, 7B, 7C, 7D and 7E may be prepared as shown by Figs. 5(a), 5(b), 5(c), 5(d) and 5(e). Explaining in details with respect to the blocking mechanism of the present invention, in order to set the flow rate of the flow rate switching device, an user select one of the five kinds of plate-like members 7A, 7B, 7C, 7D and 7E shown by Figs. 5(a), 5(b), 5(c), 5(d), 5(e) and 5(f) in compliance with a desired flow rate, and insert the selected plate-like member into the engaging holes 421. For example, in these drawings, Fig. 5(a) shows a state of the constant flow rate paths 31, 32 and 33 before blocking the flow paths. Fig. 5(b) shows a state where all of the constant flow rate paths 31, 32 and 33 are blocked. Fig. 5(c) shows the state where the constant flow rate paths 31 and 32 are blocked. Fig. 5(d) shows the state where the constant flow rate path 31 is blocked. Fig. 5(e) shows a state where the constant flow rate paths 31 and 33 are blocked. Fig. 5(f) shows a state where the constant flow rate path 32 is blocked. Further, in order to block the constant flow rate paths 32 and 33, the plate-like member 7B turning leftside rightword is inserted in Fig. 5(c). In order to block the constant flow rate path 33, the plate-like member 7C turning leftside rightword is inserted reversely in Fig. 5(d). In detaching the plate-like member (for example 7B), as shown by Fig. 6, the pair of engaging arms 71 are bent inwardly, whereby the engagement is released. Incidentally, the housing 4 according to the present invention can be used at any number of times so far as the constant flow rate path blocking mechanism operates normally, that is, the engagement state of the engaging arms and the engaging holes is normal. According to the multi stage type flow rate switching device of the present invention, the relationship between combinations of flow paths and the flow rate is as illustrated by Table 1 when the flow rates of the constant flow rate paths are set as follows. As is apparent from the above-described explanation, the multi stage type flow rate switching device of the present invention is provided with a simple structure where the constant flow rate paths are pressed to block by the clamping means. Therefore, the present invention has advantages where the fabrication is facilitated and the device can be fabricated at a low cost. Further, flow path switching operation is simple and accordingly, erroneous operation is rarely caused.

Claims: A multi stage type flow rate switching device comprising: a liquid medicine flow inlet port (1) having plural branch paths (11, 12, 13) on a downstream side; a liquid medicine flow outlet port (2) having plural branch paths (21, 22, 23) on an upstream side; constant flow rate paths (31, 32, 33) for connecting the plural branch paths (11, 12, 13) of the liquid medicine flow inlet port (1) and the plural branch paths (21, 22, 23) of the liquid medicine flow outlet port (2); A housing (4) comprising a lid (41) and a housing main body (42), said housing (4) being capable of accommodating and arranging the plurality of constant flow rate paths (31, 32, 33); and clamping means provided in the housing (4), said clamping means being capable of selectively blocking the plural constant flow rate paths (31, 32, 33); characterised by the clamping means being constituted by plate-like members (7) having engaging means for engaging with the housing (4), and being insertable from a slit (412) provided at the lid (41) of the housing (4), wherein said plate-like members (7) are stepwisely provided with constant flow rate path blocking portions and constant flow rate path nonblocking portions, the constant flow rate path blocking portions being thicker than the constant flow rate path nonblocking portions, and wherein a desired flow rate can be selected by using several kinds of said plate-like members (7) each having a different stepped shape.

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