Mixing valve with hydraulic responsive movable field
TECHNICAL FIELD 
     This invention relates to faucet valves and more particularly single handle mixing valves that incorporate sliding valve plate members. 
     BACKGROUND OF THE INVENTION 
     Faucet valves that incorporate sliding ceramic plates have many advantages over other types of faucet valves. The ceramic elements are durable and provide for long life with virtually no leakage between the two highly polished valving surfaces of the respective ceramic valve elements. However, in order for the ceramic valves to work in the faucet environment, the valves must be slidable under compressive force. Commonly, this compressive force is obtained by having the lower stationary valve member seated on resilient elastomeric seals. The upper portion of the valve must have all its elements dimensioned precisely so that the movable valve element will be under compressive force. Manufacturing tolerances have to be within a certain range in order for the resilient elastomeric seal to function properly. If the total height of the internal valve members is too great, the elastomeric seal becomes overly compressed and the ceramic valve members are pressed against each other with too great a force and are therefore hard to operate. 
     On the other hand, if the total height of the internal valve members is too little, the resilient elastomeric seal pushes the fixed valve element fully upward; however, the two ceramic valve members are still not adequately pressed together so that leakage between the fixed ceramic plate and the movable top ceramic plate still occurs. 
     Hydraulic pressure can be used to press the stationary valve up against the ceramic valve plate. Hydraulic pressure is used to press ceramic plates together in a faucet valve disclosed in my U.S. Pat. No. 4,250,912 issued on Feb. 17, 1981 entitled &#34;A Faucet Valve&#34;. 
     However, in single handle mixing valves it must be assured that the hydraulic pressure not only pushes the cartridge portion upward to press the fixed plate against the movable plate, but also that separation between the cartridge lower section and the fixed plate does not occur due to the same hydraulic pressures. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, a mixing valve for a faucet includes a faucet body that receives a cartridge. The cartridge includes an axially movable cartridge bottom section with a fixed plate seated on the cartridge bottom and a movable plate mounted on the fixed plate. The movable plate is connected to controlling means and cooperates with the fixed plate so as to regulate water flow rates in mixing proportions. The cartridge bottom is axially movable and responsive to hydraulic pressure and moves upward to exert a compressive force between the movable fixed plate and cartridge bottom itself. 
     The upward movement is provided by hydraulic pressure exerted on the working surface area within the seals that are interposed between the cartridge bottom and faucet body. The working surface area of these seals is larger than the total working area within the seals between the cartridge bottom and the fixed plate. Therefore the hydraulic pressure interposed between the fixed plate and cartridge bottom which would tend to separate the two elements is overcome by the greater hydraulic pressure exerted on the cartridge bottom to bias the cartridge bottom against the fixed plate and in turn the movable plate. Hence the cartridge bottom acts as a piston that is biased upwardly and prevails against any hydraulic pressure which would tend to separate the fixed plate from the cartridge bottom. 
     The compressive force exerted between the fixed plate and movable plate assures against leakage and provides for the correct operation of the valve plates. 
     In those cases when hydraulic pressure is lacking or before or after the faucet installation attachment of the valve plates can take place, to prevent separation, a spring can be placed between the faucet body and the cartridge bottom to exert an upward bias onto the cartridge bottom. 
     Furthermore, because the cartridge bottom is axially movable, it can compensate for every manufacturing tolerance and for cartridge thermal expansions thereby avoiding any improper operation of the faucet due to these potential problems. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference now will be made to the following drawings in which 
     FIG. 1 is a segmented view of a mixing valve according to the invention; 
     FIG. 2 is a top plan view of the cartridge bottom containing the seals for the fixed plate. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A faucet, according to the invention, contains a body 1 at whose bottom arrive two water flow pipes 7 and 8, respectively hot and cold, which open in correspondence with the seating bores 3 and 4 in the bottom of the faucet body 1. The body 1 has a cartridge receiving chamber 2A and an annular chamber 2 communicating with an outlet connection not represented. The body 1 includes a closure cap 5 which has a seal 6. The cap is screwed as usual, but it has a peripheral knurl 5A through which the cap 5 can be hand applied or hand removed. 
     The cartridge 2 includes a bottom envelope 10 which is preferably built with plastics and is introduced into the boring of the faucet body 1 with axial mobility. The envelope 10 has two extending connections 11 and 12 provided with seals 15 and 16. Each seal is suitably sized to penetrate and to be sealed in the seating bores 3 and 4 of the faucet body which communicate with the pipes 7 and 8. Each connection 11 and 12 has a passage 11A and 12A therethrough. The passages 11A and 12A are surrounded inside the envelope 10 by a seal 17 which is, in this case, replaced by two separated annular shaped pieces housed in corresponding seats inside the envelope bottom 10. The seal 17 could be composed of a single piece with a more complex shape. The seal 17 sealingly seats a fixed valve plate 18 mounted on the seal 17 in the envelope 10. 
     The fixed plate 18 has two openings 18A and 18B in correspondence with the passages 11A and 12A for the hot and cold water outflow. In contact with the fixed plate 18 is mounted a movable valve plate 19 jointly with a control slide 20 translationally movable within a ring 21 which in turn rotates in the envelope 10. The slide 20 abuts against a half bearing 22 fixed at the opening of the envelope 10. The half bearing 22 in turn abuts against the cap 5 which closes the faucet body 1. 
     Another half bearing 23 is housed in the cap 5 and between the half bearings 22 and 23 is housed a connection ball 25 which is sealed by a seal 24. An arm 26 extends outwardly from ball 25 to which is connected a handle member 28 with a driving lever 29. A second arm 27 extends inwardly from the ball 25. The arm 27 is flat and works in a corresponding seat of the control slide 20. 
     This construction is known and allows, by differently rotating and inclining the lever 29, to shift the control slide 20 and then the movable plate 19, in translation and rotation over the fixed plate 18 so as to regulate the total and proportional flow which, coming from the pipes 7 and 8, enters chambers 2A and 2 before being discharged into the spout (not shown). Interposed between the bottom of the carriage envelope 10 and the body bottom 1 is placed a spring 30 consisting of a perforated disc for the passage of the extending connections 11 and 12. The disc is cambered for working as a repulsion elastic spring between the body bottom 1 and the bottom of the cartridge envelope 10. This spring 30 is constructed so as to supply a biasing force sufficient to assure the abutment between the plates 18 and 19 of the faucet, and the application by a certain pressure of the bottom 10 of the cartridge envelope, through the seal 17 and against the fixed plate 18. 
     Independently of the feeding pressures for hot and cold water, the spring 30 exerts a force on the bottom of the cartridge envelope 10 directed towards the cap 5. The force is transmitted from the envelope bottom 10 to the fixed plate 18 and from the latter to the movable plate 19, to the slide 20, to the half bearing 22 and to the cap 5. The force keeps in contact the cartridge bottom 10 and the fixed plate 18 (through the seal 17) and the plates 18 and 19 together. Therefore, the spring assures a regular working of the faucet at low pressure. 
     The water pressure through the pipes 7 and 8, works on the extended connections 11 and 12 so the extended connections function like a piston, pushing the envelope 10 toward the discs 18 and 19. The pressure, working inside the envelope bottom 10 in the space limited by the seal 17, is inclined to separate this bottom from the fixed disc 18. This negative force turns out to be lesser (due to the lesser working area with seal 17 relative to the working area within seals 15 and 16 as shown in FIG. 2) than the positive force exerted on the extended connections 11 and 12; so the net force is directed toward the cap 5, and prevails against the force inclined to separate the envelope bottom 10 from the disc 18 and the two discs 18 and 19 one from the other. 
     As a consequence, although the feeding pressure increases, an adequate adhesion between the plates and between them and the bottom of the cartridge envelope is always guaranteed. As no appreciable force of inertia concerns the operation of the faucet, the hydraulic pressure forced compression of the plates and bottom not only occurs in static conditions but in the presence of water hammers as well. 
     Proper planning and sizing of the components allows in most cases to proportion the force exerted by the water pressure so as to avoid over compression between the plates which can cause faucet motion to be too hard or stiff in the presence of high supply pressures. However, if it is necessary, it is also possible to limit the action of the pressure. For example, a gap 40 existing between the abutment shoulder 44 of envelope 10 and the abutment shoulder 42 of cap 5 such that, after a prefixed compression of the inner parts of the cartridge, the abutment shoulder 44 of envelope 10 abuts against the cap shoulder 42 thus directly shunting any force exceeding a prefixed limit from being exerted onto the plates 18 and 19. 
     The spring for precharging between the faucet body and the cartridge, can also be fashioned in a different form than that of one spring or more. For example, as shown in FIG. 1, the seals 15 and 16 of the extending connections 11 and 12 can extend with elastic appendices 15A and 16A as far as the bottom of the faucet body supplying the precharging force. The springs, as shown according to FIG. 1, can co-exist or can be present singly or can be replaced by any other suitable springs. However, the existence of a precharging spring is not essential for the application of the invention. Particularly in those cases when we do not think that an accidental detachment between the plates or between the fixed plate and the cartridge bottom may occur, or when measures for preventing it (for example, the application of a grease able to keep the parts together during the transport and installation) are taken, or when it is foreseen that the plumber is careful to establish or re-establish the adhesion among the parts before starting fluid flow, we can eliminate the usage of any precharging elastic tools and use only the action of the hydraulic pressure. 
     The cartridge used in the represented realization form is a complete replaceable cartridge containing all the control mechanisms of the faucet. However, for the application of this invention, the cartridge can reduce to a simple movable bottom provided with seal connections operating between this bottom and the seats of the faucet body and supporting through a seal, the faucet fixed plate; in this case, the mechanisms can be put together directly in the faucet body. The reduced cartridge can be adopted when it is not necessary to replace the mechanisms easily and quickly. 
     Of course, different changes in addition to those above mentioned can be made to what is described and shown. For example, the cap 5 can be affixed to the body through a bayonet joint or through an elastic clip or in another manual way. The particular form of the inner mechanisms of the cartridge is not important for the application of the invention and when it can vary in comparison to the above mentioned. 
     Variations and modifications of the present invention are possible without departing from the scope and spirit as defined in the appended claims.