LIQUID STORAGE TANK

Abstract: A liquid storage tank having a feed port (3) provided with a float valve (4) for opening and closing same. The float valve (4) includes a float member (8) and a rod member (9) having one end connected to the float member (8). The other end of the rod member (9) is fitted into a valve seat (7), which is formed on the inner periphery of a feed pipe (5) constituting the feed port (3), and provided with a valve plug portion (10) for opening and closing the valve seat (7). When the level of the liquid in the tank is lowered together with the float member (4), the rod member (9) is tilted so that the valve plug portion (10) is partially separated from the valve seat (7) to open the feed port (3). When the float member (4) is in such a position as to support the rod member (9) in a horizontal position, the valve plug portion (10) is seated on the valve seat to close the feed port (3). The pressure of the supply of liquid acts on the valve plug portion (10) against the valve seat (7).

Description: The present invention relates to a liquid storage tank. For continuous discharge or intermittently continuous discharge of liquid under such pressure and at such flow rate as required when said liquid is supplied under pressure a large-type liquid storage tank is generally employed as, for example, a cistern of a flush toilet, wherein water is stored for a periodical discharge in large quantities or in an elevated water-service tank installed on a building roof or at the like location, wherein water is stored after being pumped up. In such storage tanks liquid is normally stored at a constant level through automatic supply of the same into the tank as required, and for this purpose a float valve is employed such that liquid supply is automatically stopped when a target liquid level is reached. The manner of liquid level control by a float valve will be explained in detail hereinbelow. In the following description, the liquid involved is understood to be water. A liquid storage tank according to the preamble part of claim 1 is known from US-A 3 095 896. A float valve is arranged inside of a tank body at a sidewall thereof and being connected to a float member by a connecting rod. Said connecting rod is at one end thereof loosely adapted to a valve seat of said float valve and at its opposite end firmly attached to an upper part of said float member so that said float member has to rotate around a bearing part of said valve seat between two positions upon buoyancy according to an increasing or decreasing of liquid in said tank body and thereby opening or closing said float valve at said valve seat, respectively. The enforcement to rotational movement of said float member and the arrangement of said valve body inside of said tank body strongly restrict the adjustment of the opening and closing positions of said float member in response to a certain liquid level. The same disadvantages are known from the subject of the prior art being disclosed in US-A-2 684 077. A control valve is coupled to the discharge end of a hose. Said control valve comprises a tank body, a float valve and a float member, wherein said float valve is at least partly arranged at the inside of said tank body and being connected to said float member by a connecting rod in the same manner as known from US-A-3 095 896 so that also a rotational movement of said tank body is enforced. Any such conventional liquid storage tank, as described above, is designed primarily for storing a large quantity of liquid therein. In the above prior art there has been made no proposal oriented toward compactness of such tank or of the float valve component thereof. True, in the areas where large-type storage tanks are required, there is no particular need for compactness. Since the liquid feed stopping mechanism employing a float valve is to stop liquid feed against the feed liquid pressure involved, a large-size float member and a considerably long arm member are required to provide sufficient water stopping force that can overcome the pressure (3-5 kg/cm²), which necessarily results in a large-size construction for the float valve. However, in the case of supplying water to a humidifier, for example, it is required that the water supplied under pressure must be first stored in a tank and subsequently released from the tank intermittently continuously and steadily in predetermined small quantities under atmospheric pressure. If the humidifier itself is not so large in size and if a storage tank for supplying water under such conditions is to be incorporated in the humidifier, a small-size storage tank is required. Needless to say, it is unjustifiable and undesirable to employ a float valve of any such conventional type as above described in such small-size storage tank. However, it is also unjustifiable to use a high-performance regulator, valve, or the like for control purpose, because it involves a great deal of complexity in respect of control mechanism and high costs of equipment. The object of the present invention is to provide a liquid storage tank of a small and simple construction for continuously storing and discharging small quantities of a liquid. This object is achieved by a liquid storage tank having feed port provided in a sidewall of a tank body and a float valve for opening and closing same, said feed port is formed by a feed pipe which has a diametrically reduced portion radially inwardly projecting from inner wall periphery thereof to form a valve seat for the float valve on a upstream side surface of said reduced portion, said float valve comprises said valve seat and a float member movable upward and downward according to the liquid level in the tank body and a connecting rod member having one end connected to said float member and the other end passing through said diametrically reduced portion of the feed pipe, said rod member having a valve plug portion formed thereon at said other end thereof, said plug portion extending radially outwardly of said rod member in a collar-shape pattern so as to seat itself and said valve seat, wherein said float valve is arranged at the outside of said tank body, and that said one end of the rod member is fitted into a horizontal hole extending inwardly said float member from one side thereof. In the liquid storage tank according to the present invention the float member may be adapted to reduce the liquid contained in the tank body to minimum quantity. Consequently, supplying and discharging of a liquid in predetermined small quantities can be easily adjusted. Further advantageous features for controlling the liquid supply and its discharge and for an easy handling with a liquid storage tank of the present invention are expressed in subclaims 2 to 8. These and other objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings, in which: Figs. 1 and 2 are sectional views showing the schematic arrangement of a liquid storage tank according to a first embodiment of the present invention, Fig. 1 showing the tank as it appears when the float valve is in closed condition, Fig. 2 when the float valve is in opened condition; Figs. 3 and 4 are enlarged, detailed views showing relevant parts of the diametrically reduced portion in Figs. 1 and 2; Fig. 5 is a sectional view of a liquid storage according to a second embodiment of the present invention, similar to Fig. 1; and Figs. 6 and 7 are, respectively, sectional views showing schematic arrangements of the prior art storage tanks, as previously described. Preferred embodiments of the present invention will now be described with reference to Figs. 1 to 5. Figs. 1 and 2 are sectional views showing the arrangement of the storage tank according to a first embodiment of the invention, Fig. 1 showing the tank as it appears when a float valve is in closed condition, Fig. 2 when the float valve is in opened condition. As shown, the storage tank comprises a body 1b and a lid 1a covering the upper opening of the body 1b. The body 1b includes a sidewall 2 having a feed port 3. The float valve 4 is provided in the feed port 3, said valve 4 having a function to open and close the feed port 3. The feed port 3 consists. of a feed pipe 5 connected to the side wall 2 of the tank body 1. The feed pipe 5 has a radially inwardly projecting portion 11 formed on its inner wall periphery, said projecting portion 11 defining a diametrically reduced portion 6 for narrowing a path of liquid flow. Figs. 3 and 4 are, respectively, enlarged detail views showing relevant parts of the diametrically reduced portion 6 seen in Figs. 1 and 2. A valve seat 7 for the float valve 4 is formed on the upstream side surface of the projecting portion 11 defining the diametrically reduced portion 6. The valve plug-side components of the float valve 4 include a float member 8, and a rod member 9 fixedly connected at one end to the float member 8 and fitted at the other end side in the diametrically reduced portion 6 of the feed port 3. The rod member 9 has a valve plug portion 10 formed thereon at said other end side, the plug portion 10 extending radially outwardly of the rod member 9 in a collar-shape pattern so as to seat itself on the valve seat 7 through an O-ring 12. A force working for seating the valve plug portion 10 on the valve seat 7 is a liquid feed pressure acting on the rear surface 13 of the valve plug portion 10 from the upstream side and in the direction of the arrow A shown. The density of the float member 8 is slightly lower than that of the liquid supplied. Accordingly, the float member 8 has a comparatively large weight. Thus, the float member 8, though quite small in size (volume), still has a justifiably sufficient weight. By virtue of this fact, the rod member 9 serving as a moment arm, though quite short in length, can provide sufficient moment for disengaging the valve plug portion 10 from the valve seat 7. In the present embodiment, the float member 8 is tapered over its side periphery at portions above and below the point at which the rod member is connected to the float member 8, so that if the liquid level in the tank is excessively lowered by any reason whatsoever, the side periphery goes into abutment with the inner wall surface of the tank body 1 through surface contact or line contact to prevent the rod member 9 or the valve plug portion 10 from being inclined more than necessary, thereby to prevent the weight of the float member 8 under insufficient buoyancy from acting on the surface of contact (point contact) between the valve plug portion 10 or the 0-ring 12 and the valve seat 7, or the surface of contact (point contact) between the rod member 9 and any corner of the projecting portion 11 to damage such portion or surface. Aforesaid liquid feed pressure, if water feed pressure from a water service line, for example, is normally of the order of 3 kg/cm² - 5 kg/cm²; however, the tank 1 is provided on the top thereof with a vent port 14 so that the interior of the tank 1 is under atmospheric pressure. Therefore, the liquid from the storage tank is supplied at the gage pressure of 0 kg/cm². In the present embodiment, the volume of the float member 8 is designed large relative to the internal volume of the tank, so that the amount of liquid storage is rather small. This provides the advantage that the liquid level is lowered at a large degree in relation to the predetermined small rate of liquid discharge, whereby highly sensitive valve opening and closing in response to changes in the liquid level can be assured. Nextly, a second embodiment shown in Fig. 5 will be explained. This embodiment represents improvements in the first embodiment. A liquid storage portion lb of the tank body 1 comprises two parts, namely, a cylindrical member 1b - A and a bottom member 1b - B screw-connected to the lower edge of the cylindrical member 1b - A. According to this construction, the bottom member 1b - B can be separated from the cylindrical member 1b - A. This permits easy removal of dust and the like foreign matter settled in the bottom member 1b - B. The bottom member 1b - B is formed with a drain hole 16 which is removably stopped by a plug 16. A vent hole 14 is bored in a sidewall 2 of the cylindrical member 1b - A. This vent hole 14 is located at a position opposite to a lower peripheral edge portion of a lid 1a screw-connected to the upper outer periphery of the cylindrical member 1b - A. According to this arrangement, in the event that the float valve 4 fails to operate by some reason with the result that water supply into the tank cannot be stopped, water is allowed to gradually leak outward through the vent hole 14, then flowing downward along the outer wall of the tank body 1. Even if the water pressure within the tank is abnormally high, water is prevented from jetting out through the vent hole 14 because the lower peripheral edge of the cover member 1a serves to resist such jetting out. Hence, there is no possibility of water jetting out through the vent hole 14. A discharge port consists of a discharge pipe 14′ This discharge pipe 14′ extends centrally through the lid la and is fixed thereto. A float member 8 has a longitudinal through-hole 8a centrally bored therein. The discharge pipe 14′ extends through the longitudinal through-hole 8a. The inner diametral size of the longitudinal through-hole 8a is considerably larger than the outer diametral size of that portion of the discharge pipe 14′ which extends through said through-hole 8a so that the float member 8 is tiltable in response to changes in the liquid level. In assembling operation, the positioning of the float member 8 in the tank body 1 can be carried out with the aid of the discharge pipe 14′. The connection of the rod member 9 to the float member 8 need not be a fixed-type connection. In the present invention, any type of connection may be used only if the tilt movement of the float member 8 is well transmitted to the rod member 9. In the second embodiment, as is apparent from Fig. 5, the float member 8 is formed with a horizontal hole 8b extending inwardly from one side thereof, the free end of the rod member 9 being loosely fitted into the horizontal hole 8b. In the second embodiment, a feed pipe 5 comprises a first feed pipe 5a and a second feed pipe 5b mounted in a direction perpendicular thereto. The feed pipe 5 in the first embodiment corresponds to the feed pipe 5a in the second embodiment. One characteristic feature of the feed pipe 5 in the second embodiment is that a coil spring 18 is interposed between the first and second feed pipes 5a, 5b. Another characteristic feature is that the second feed pipe 5b is fitted with a strainer. The strainer 19 is held in position by a holder 19b therefore, and the holder 19b is stopped by a strainer cap 19a against slip off. The coil spring 18 is, at one end, in contact with the rear surface of the valve plug portion 10 and, at the other end, with the inner surface of the strainer cap 19a. This coil spring 18 constantly presses the valve plug portion 10 against the valve seat 7, but does not interfere with the tilting movement of the float member 8 with changes in the liquid level. Through the provision of such coil spring 18 it is possible to assure good sealing of the valve plug portion 10 against the valve seat 7.

Claims: A liquid storage tank having a feed port (3) provided in a sidewall (2) of a tank body (1) and a float valve (4) for opening and closing same, said feed port (3) is formed by a feed pipe (5) which has a diametrically reduced portion (6) radially inwardly projecting from inner wall periphery thereof to form a valve seat (7) for the float valve (4) on an upstream side surface of said reduced portion, that float valve (4) comprises said valve seat (7) and a float member (8) movable upward and downward according to the liquid level in the tank body (1), and a connecting rod member (9) having one end connected to said float member (8) and the other end passing through said diametrically reduced portion (6) of the feed pipe (5), said rod member (9) having a valve plug portion (10) formed thereon at said other end thereof, said plug portion (10) extending radially outwardly of said rod member (9) in a collar-shape pattern so as to seat itself on said valve seat (7), characterized in that said float valve (4) is arranged at the outside of said tank body (I), and that said one end of the rod member (9) is fitted into a horizontal hole (8b) extending inwardly said float member (8) from one side thereof. A liquid storage tank as claimed in claim I , characterized in that said float member (8) is provided with a through hole (8a) substantially perpendicular to said bore hole (8b) and separated therefrom, and that a discharge port is arranged in a cover member (1a) of said tank body (1) and comprises a discharge pipe (14') projecting into said tank body (1) and extending into said through hole (8a) with clearance therebetween. A liquid storage tank as claimed in claim 1 or 2 characterized in that said rod member (9) is loosely fixed to said float member (8) at one end thereof and is urged towards the valve seat (7) of said float valve (4) at the other end thereof by a spring member (18). A liquid storage tank as claimed in claim 1 to 4, characterized in that said tank body (1) comprises a bottom member (1b-B), a cylindrical member (1b-A) and said cover member (1a), wherein said cover member (1a) is screw connected with said cylindrical member (1b-A) and said cylindrical member (1b-A) is screw connected said bottom member (1b-B). A liquid storage tank as claimed in one of claim 1 to 4 , characterized in that said tank body (1) has a vent hole (14) for constantly providing an atmospheric pressure in the interior of said tank body (1). A liquid storage tank as claimed in claim 6 , characterized in that said vent hole (14) is arranged in an upper section of said cylindrical member (1b-A) to which said cover member (1a) is adapted to cover said vent hole (14) with a peripheral edge thereof. A liquid storage tank as claimed in one of claims 1 to 6 , characterized in that said float member (8) has a central portion extending in a direction parallel to said feed pipe (5) substantially across the entire internal width of said tank body (1) and that said float member (8) also has upper and lower portions tapered from respective opposite sides of said central portion for allowing the float member to respectively tilt downwardly and upwardly. A liquid storage tank as claimed in claim 7 , characterized in that said upper portion also prevents the float member (8) from tilting more than a predetermined amount by abutting a side of the tank body (1) when said float member (8) has tilted said predetermined amount.

Inventors: FUKUSHIMA, KAZUHIRO, MIZUNO, TAKEO, OONISHI, NORIO
Applicants: H. IKEUCHI & CO., LTD.
Application year: 1987
Main classification: E03D1
IPC codes: F16K31, F16K33