Patent Publication Number: US-5254815-A

Title: Reservoir tank including float with reed switch unit

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a reservoir tank for storing therein an amount of operating fluid to be supplied into a device such as a brake master cylinder or a clutch release cylinder. 
     In a conventional reservoir tank of the type is disclosed, for example, in Japanese Utility Model Publication No. 62(1987)-5415 published after examination on Feb. 6, 1987, a reservoir tank for storing therein an amount of operating fluid has a bottom under which a hole is formed. Within the hole, a reed switch unit assembly having a reed switch is inserted which is interposed between a power supply and a lamp, both of which are connected in series. The reed switch is set to be closed by a magnet which is secured to a float on the operating fluid whenever the liquid level thereof lowered below a set value. In light of the fact that in this device the reliability thereof depends on a relative position of the reed switch to the magnet, the reed switch is accommodated in a casing in such manner that the reed switch is located in place by pawl means formed in the casing and is fixed by an amount of epoxy resin filled in the casing. 
     However, in light of the fact the need for forming of pawl means in the casing and the filling the epoxy resin thereinto, it is cumbersome to constitute the foregoing reed switch unit assembly. In addition, the size of the casing must be larger than that of the reed switch, which is contrary to the recent light-weight requirement for an automotive component. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the invention to provide a reservoir tank without the above conventional drawbacks. 
     It is another object of the invention to provide a reservoir tank in which a reed switch unit assembly is simple in structure. 
     It is further object of the invention to provide a reservoir tank in which a reed switch unit assembly is simple to manufacture. 
     In order to attain the foregoing objects, a reservoir tank according to the present invention is comprised of a tank body storing an amount of operating fluid, connected to a specific device for supplying thereinto the operating fluid and having a bottom with a hole isolated from the operating fluid; a float movable in the vertical direction according to the variation of the liquid level of the operating fluid; a magnet secured to a lower end of the float; and a reed switch unit assembly having a reed switch with a pair of terminals, a pair of conducting elements connected to the pair of terminals of the reed switch, a connector casing, and a pair of connectors each of which is secured to one end of the connector casing in such a manner that each connector is electrically connected to the respective conducting element. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will be more apparent and more readily appreciated from the following detailed description of preferred exemplarily embodiments of the present invention, taken in connection with the accompanying drawings, in which; 
     FIG. 1 is a cross-sectional view of a reservoir tank according to the present invention; and 
     FIG. 2 is a side view with a partial cross-section of a reed switch unit assembly. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2, a reservoir tank 1 in which an amount of operating fluid is stored includes a pair of spaced connecting holes 3 and 3, each of which is in the form of an extension or a projection to be connected to a respective hole (not shown) of a master cylinder (not shown). It is to be noted that the reservoir tank 1 can be connected to a similar apparatus such as a clutch release cylinder. Thus, the operating fluid is set to be supplied into the master cylinder. The reservoir tank 1 has an opening at its upper end portion, which is detachably mounted with a cap 2 made of an elastic material such as a rubber. 
     Within the reservoir tank 1, a fluid chamber 5 is defined which is surrounded by a pair of walls of the tank 1 and a pair partitions 4 and 4. In the fluid chamber 5, a float 6 which is provided at its lower end Portion with a magnet 7 is accommodated so as to be guided or moved along a shaft 11 in accordance with the liquid level of the operating fluid which is upstanding from a bottom la of the reservoir tank 1. 
     Below the bottom 1a of the reservoir tank 1, there is formed a hole 10 whose axis is pendicular to that of the shaft 11. In the hole 10, reed switch unit assembly 20 is set to be accommodated which has a reed switch 21 to be closed when a magnetic force from the magnet 7 exceeds a set value as a result of the lowering movement thereof. 
     As best shown in FIG. 2, the reed switch unit assembly 20 has a connector casing 22 made of a synthetic resin. The connector casing 22 includes a main body 22a provided at its right end portion with a cavity 22b with an opening 22c. A pair of parallely spaced connectors 250 each of which is secured at its left end to the main body 22a of connector casing 22, and its right end of each connectors 250 is positioned with in the cavity 22b so as to be oriented toward the opening 22c. A sub body 22d is formed integrally with a left end of the main body 22a. The main body 22a and the sub body 22d have a common axis and the radius of the former is larger than that of the latter. Between the connectors 250, a power supply 30 and a warning lamp 31 which are connected in series are interposed. 
     A first conducting element 23 is secured at its right end to the sub body 22d so as to be electrically connected to one of the connectors 25. The first conducting element 23 is extended away from the sub body 22d and terminated in an upwardly 90-degree distal bent portion 23a. A second conducting element 25 is secured at its right end to the sub body 22d so as to be electrically connected to the other connector 250. The second conducting element 25 is extended away from the sub body 22d and the left end or distal end 25a of the second conducting element 25 is brought into opposition to the distal end 23a of the first conducting element 23 at a distance. The reed switch 21 with a pair of terminals 24 and 24, each of which is in the form of a wire, is located between the distal end 23a of the first conducting element 23 and the distal end 25a of the second conducting element 25 and the terminals 24 and 24 of the reed switch 21 are electrically connected to the distal end of the first conducting element 23 and the distal end 25a of the second conducting element 25 means of soldering. A pair of walls 23c and 23c (only One is shown) are extended integrally in the upward direction from the first conducting element 23 in such a manner the reed switch 21 is to be located therebetween. In other words, a cross-section of the resulting portion is a substantially U-shaped configuration which accommodating the reed switch 21. The walls 23c and 23c are used for Protecting longitudinal sides of the reed switch 21. 
     It is to be noted that the electrical connection between a right end of the second conducting element 25 and the other connector 250 is in the form of the eccentric connection 25b in order to prevent effecting the reed switch 21 even if an unexpected pulling force acts to the other connector 250. An O-ring 27 mounted on the sub body 22b adjacent to the main body 22a serves for the fluid-tight seal between the hole 10 and the connector casing 22. A grommet 26 is provided to the connector casing 22 for the water-proof sealing thereof. 
     In the illustrated condition, though the reed switch 21 is rested on the first conducting element 23, the reed switch 21 can be spaced away from the first conducting element 23 by reinforcing the strength of each terminal 24 of the reed switch 21. 
     The connection between one connector 250 and the first conducting element 23 (between the other connector 250 and the second conducting element 25) is established during the molding formation of the connector casing 22. 
     In the present invention, the conducting elements 23 and 25 are used for the positioning of the reed switch 21, which ensures a simple structure of the reed switch unit assembly 20. Therefore, so long as the assurance of the precise size of the connector casing 22, the relative position between the magnet 7 and the reed switch 21 after the installation of the reed switch unit assembly 20 in the bottom la of the reservoir tank 1 is a substantially stable, which assures the reliability of the function of the reed switch unit assembly 20. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.