Positive displacement flowmeter

Abstract: A positive displacement flowmeter comprising a flowmeter portion including a pair of rotors rotatable in proportion to a fluid's flow in a measuring chamber and a counting portion for measuring a total flow by counting the rotor's rotations. It has many improvements. Firstly, the flowmeter is protected against the penetration of rain water into its counting portion. Furthermore, the counting portion housing is so constructed as to assure the easy mounting of an electric circuit and like components therein and also the possibility to control said circuit from the outside of the housing by use of reed switches and the like. The flowmeter is improved not to transfer heat of a fluid of high temperature to the counting portion and, furthermore, to assure the easy mounting of rotors in the measuring chamber. Particularly, it is possible to provide high performance rotors mounted in the measuring chamber by using non-circular gears having a special tooth profile and made of special materials. Other various improvements are presented.

Description: BACKGROUND OF THE INVENTION Conventional type flowmeters, each of which has an indicator unitarily attached to its body and is connected to a pipe by means of flanges or like joining means, are generally used for measuring and indicating the fluid's flow by processing a flow-rate signal from a measuring portion. There have been many applications of positive displacement flowmeters of this type. The positive displacement flowmeter, operating on the principle of a constant volume of fluid discharged by a rotor rotating in a measuring chamber of the flowmeter's body, is usually mounted with its rotor shaft horizontally positioned so as to correctly measure the fluid's flow-rate proportional to the rotation of the rotor without causing any undesirable rolling friction. Furthermore, when the flowmeter is mounted on the piping, its indicating portion is attached to the flowmeter's body horizontally along the axis of the flowmeter so as to vertically dispose the indicating panel for easily reading it. The positive displacement flowmeter's body is attached at its flanges to a pipeline through which a fluid to be measured flows. A counting portion having the function of processing the flow-rate's signal and to indicate the value obtained is accommodated in an outer housing which is removably attached to the flowmeter's body through an outer connecting housing with setscrews in deeply counter-bored holes in the outer housing. However, in the case where the flowmeter is mounted on outdoor piping, rain water may accumulate in the deeply counter-bored holes and penetrate through the threaded portions of the set-screws into a small clearance between the inserted pipe of the outer indicator housing and the inserted hole of the outer housing, which during a long period of time may exert an adverse effect on the inner devices of the counting portion and also make it impossible to remove the inserted part of the outer indicator housing from the connecting housing due to the rusting of its inserted part. SUMMARY OF THE INVENTION It is an object of the invention to provide a positive displacement flowmeter which is so constructed as to discharge rain water collected in counterbored bolt holes of a flow-rate indicator, attached to the flowmeter body, by using bolts in said holes. This object is achieved by the claimed apparatus. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view showing a positive displacement flowmeter according to the present invention; Figure 2 shows a detailed portion of the embodiment of Fig.1; Figure 3 is a sectional view taken along line III-III of Fig.2; Figure 4 is a perspective view showing the mechanism for the mounting devices; Figure 5 is a sectional view taken along line V-V of Fig.4; Figures 6 and 7 are sections taken on lines VI-VI and VII-VII, respectively, in Fig.5; DESCRIPTION OF PREFERRED EMBODIMENTS Fig.1 shows an example of a flowmeter which is composed of a body 30 having flanges 30a and 30b for connecting to a pipeline (not shown), a counting portion 10 incorporating therein a counting unit capable of processing a flow-rate signal to be indicated on a flow-rate indicating unit 10a, and a connector housing 20 for removably connecting the device housing 10 to the body 30 of the flow meter. As shown in Fig.2, the device housing 10 is secured to the connector housing by means of set screws 3 screwed into counterbored threaded holes 4 in the connector housing. Fig.2 is a detailed view showing an example of attaching the device housing 10 to the connector housing. As shown in Fig.2, the device housing has an inserting cylindrical portion 1 extending concentrically and outwardly, which is inserted into a receiving hole 20a concentrically drilled in the connector housing 20, and which is clamped therein by set screws 3 screwed through the counterbored holes 4, two (upper and lower) pairs, arranged symmetrically to each other along line III-III of Fig.2 at both sides of the connector housing 20. Since the connector housing 20 is made in the same form as the device housing 10, they can be unitarily connected as shown in Fig.1. The inserting cylindrical portion 1 of the device housing and the receiving hole 20a of the connector housing do not always need to be concentric with their housings respectively, i.e. if both housings may be connected with each other to form a unit of the same form. Fig.3 shows a cross-section of the unitarily connected portion of both housings 20 and 10, which is taken along line III-III of Fig.2. When the flowmeter is mounted on the outdoor pipeline, rain water "W" may collect in the counterbored holes 4, as illustrated, gradually penetrating through the threaded portions of the setscrews 3 into a small clearance "g" between the receiving hole of the connector housing 20 and the insert portion 1 of the device housing 10 as shown by the letters Wa resulting in that the inner components of the device housing are subjected to deterioration from humidity and after a long period it becomes impossible to remove the insertion part of the device housing from the connector housing due to the rusting of its inserted portion. Fig.4 is a perspective view showing a method for connecting the device housing 10 to the connector housing 20. Fig.5 is a view taken in the direction of the arrows along line V-V of Fig.4. In these drawings, like parts, as those of Fig.2, are indicated by like reference characters. The connector housing 20 has a receiving ring (hole) 20a which is secured concentrically in the connector housing 20 by means of inner walls 6. In other words, the connector housing 20 is separated by the inner walls 6 from the receiving hole 20a and its counterbored holes 4 communicate with the receiving ring 20a through corresponding columned ribs 2b. Each counterbored hole 4, drilled through the columned rib 2b to an opening in the receiving ring 2a, has a thread 5 cut therein. Through-holes 9 made in the reinforcing ribs 2c between the housing 20 and the receiving ring 2a are provided for allowing the rain water to flow out. Fig.6 is a sectional view taken in the direction of the arrow along line VI-VI of Fig.5 showing the columned rib 2b. Fig.7 is a sectional view taken in the direction of the arrows along line VII-VII of Fig.5. In these drawings, a drain ditch 7 is drilled toward the inner wall 6 from the circumference of the columned rib 2b at the bottom of the counterbored hole 4. Since said drain ditch 7 is intended to discharge the rain water collected in the corresponding counterbored hole 4 through the columned rib, it is preferable to make the lower portion of the ditch deeper so as to completely drain out the rain water therethrough. A drain hole 8 is drilled through in the vicinity of the connector housing 20 above the counterbored hole 4 in the lower columned rib 2b. The above-mentioned drain system realizes the draining of the rain water collected in each of the upper counterbored holes 4 in such a way that, as shown by arrows Q in Fig.5, the rain water flows along the wall's surface 6 between the receiving ring 2a and the connector housing 20, passes through the passage hole 9 and the drain hole 8 and reaches the lower counterbored hole 4 wherefrom it is then discharged out of the connector housing. The clearance between the connector housing and the device housing is sealed with a flexible plate such as a rubber plate to prevent the penetration of the rain water into the device housing. Although the above-mentioned rain water draining system is applied to two pairs of the upper and lower counterbored holes at the opposite sides along line V-V in the Fig.4, the method described can be applied not only to flow meters, but also to any object which has counterbored holes at its upper portion, shroudings at their upper and lower portions and inner chambers allowing liquid to flow therethrough. Since according to the above-mentioned mounting method rain water can run along the vertically provided draining channel in the housing from the upper counterbored hole to the lower counterbored hole wherefrom it is discharged, there will be no effect by the rain water on the insulation of the electric circuit components in the device housing. Furthermore, the inserting and receiving portions can be prevented from rusting and the outside surface of the housing can be kept unstained by the effect of rain water making the maintenance of the flow meter easier.

Claims: A housing arrangement for use with a positive displacement flowmeter, comprising a mounting portion, having a tubular housing (20) with end faces for mounting said mounting portion to a housing of a flowmeter, and an inner cylinder (20a) concentrically and unitarily formed therein, and a tubular device portion (10), for containing a counting unit of the flowmeter, having a housing of the same cross-section as that of the mounting portion housing (20) and an inner concentric inserting cylinder (1), said inserting cylinder (1) of the device portion (10) being insertable into said inner cylinder (20a) of the mounting portion (20) and being secured therewith by use of a set of screws (3) through counterbored holes (4) formed in rib members (2b), which connect said outer housing (20) with the inner cylinder (20a), said rib members (2b) being provided at upper and lower parts of the mounting portion (20), each upper rib (2b) having a drainage hole (7) drilled in the lower wall of the counterbored portion of its counterbored hole (4) and each lower rib (2b) having a drainage hole (8) in the upper wall of the counterbored portion of its counterbored hole (4), to allow rain water entering the upper counterbored holes (4) to drain along the inner walls of the mounting portion (20) and then flow out from the lower counterbored holes(4).

Inventors: ASANUMA YOSHIO, FUJII HIROSHI, HAYAKAWA OSAMU, HOTTA KOJI, MIYAGAWA YASUHIRO, TSUCHIYA HIRONARI, YOKOTA FUMIO, ASANUMA, YOSHIO, FUJII, HIROSHI, HAYAKAWA, OSAMU, HOTTA, KOJI, MIYAGAWA, YASUHIRO, TSUCHIYA, HIRONARI, YOKOTA, FUMIO
Applicants: OVAL ENG CO LTD, OVAL ENGINEERING CO., LTD.
Application year: 1990
Main classification: G01F3
IPC codes: G01F3, G01F15, F16B37, G01F7