Abstract:
A quick, lightweight cartridge puller for hot and cold water mixing valves operates to provide an increased mechanical force advantage while applying opposed relative forces between a valve cartridge and its value housing to avoid stressing wall and decorative material supporting the valve housing. The puller includes a clamping assembly that securely and positively engages the cartridge, a draw screw, an outer body member slidably receiving the draw screw and transmitting a reactive force to the valve housing and a puller nut which is tightened onto the draw screw to create an extremely high pulling force which quickly and easily extracts the cartridge from the housing.

Description:
BACKGROUND OF THE INVENTION 
     Hot and cold water mixing valves of a type which are commonly used for showers in commercial establishments such as hospitals, hotels and school athletic departments have a removable plastic balancing chamber cartridge within a metallic valve housing. One example of such a mixing valve is the &#34;Series 400 Hydroguard&#34; manufactured by the MCC Powers Process Controls unit of Mark Controls Corporation. The cartridge contains the operative mixing mechanism and is sealed by O-ring seals to hot and cold water inlets and a mixing water outlet within the housing. 
     After an extended period of operation such valves begin to leak or otherwise fail and it becomes necessary to replace the mixing cartridge. A commonly available removal tool is provided for this purpose as illustrated in FIG. 1. This tool comprises a u-shaped wire having inwardly facing hooks formed in the extremities of the legs. A slide clamp contains two apertures and is slipped over the wire toward the closed end with each aperture receiving a leg. The two hooks are inserted into two front facing holes in a cartridge that is to be removed and engage material surrounding the holes. The slide clamp is than slid toward the clamped end until it engages a small holding notch in each leg. In this position the slide clamp maintains the tool in a closed clamped position so that the tool remains clamped to the cartridge with a reasonable degree of security. 
     When a cartridge is first installed in a housing it slides into and out of the housing relatively easily and the removal tool is fully adequate for this function. However, after several years of operation sediment from the water builds up on the seals and the cartridge becomes very difficult to extract. Frequently, the seals will tear before they break away from the housing. The removal tool shown in FIG. 1 has been found to be completely inadequate under such circumstances. The tool is incapable of providing the required pulling force under these circumstances. 
     As the tool is worked the legs bend inwardly. This allows the hooks to loosen and pull back through the engagement holes without pulling the cartridge from the housing. The cartridge must then be broken up into several pieces with a hammer and chisel in order to effect removal. This frequently takes three to four hours. Even if the tool did not pull away from the cartridge it is doubtful that the ceramic tile or other decorative wall facing that supports the valve would be sufficient to withstand the pulling force required to remove the cartridge from it housing. 
     SUMMARY OF THE INVENTION 
     A quick, light weight hot and cold water mixing valve cartridge puller in accordance with the invention includes a clamping assembly, a force transformation mechanism and an outer body member. The clamping assembly includes a generally cylindrical puller body having two clamping hooks extending therefrom which positively engage and solidly hold the cartridge at two front facing apertures. A pair of press pins transmit a locking froces from a centrally threaded locking nut to the two clamp hooks to securely lock the clamp hooks. The clamp hooks are sufficiently strong and are clamped sufficiently tight to prevent bending and gradual wear of the material surrounding the cartridge apertures. 
     The puller assembly includes a helically threaded draw screw secured to the puller body and threadedly receiving the clamping nut as well as a puller nut. After the outer body member is slid over the draw screw and clamping assembly and into engagement with the valve housing the puller nut is screwed onto the draw screw to create relative opposing forces between the draw screw and the outer body member. The threaded coupling between the puller nut and the draw screw, together with a relatively long lever arm on the puller nut, provides a force transformation mechanism having a mechanical force advantage greater than one so that an extremely large pair of opposed forces is created with modest human effort. The opposed forces are transmitted through the outer body member to the valve housing and through the draw screw and clamping assembly to the cartridge until the forces become sufficient to draw the cartridge from the housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the invention may be had from the following Detailed Description, taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a perspective view of a cartridge puller tool in accordance with the prior art; 
     FIG. 2 is an exploded perspective view of a cartridge puller for a hot and cold water mixing valve in accordance with the invention; 
     FIG. 3 is an end view of the cartridge puller shown in FIG. 2 taken from a hook end; 
     FIG. 4 is a sectional plan view of a clamping assembly used in the cartridge puller shown in FIG. 2 and take along the line 4--4 as shown in FIG. 3; and 
     FIG. 5 is a plan view of an alternative embodiment of a hook used in the cartridge puller shown in FIG. 2. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 2, a cartridge puller 10 for a hot and cold water mixing valve 12 in accordance with the invention includes a clamping assembly 14, an outer body member 16 and a puller nut 18. The valve 12 includes a valve housing 20 having a hot water inlet 22, a cold water inlet 24 and a mixed hot and cold water outlet 26 for connection to a shower (not shown). The valve housing 20 has a hollow, generally cylindrical interior which receives a valve mixing cartridge 30 having hot and cold water inlets 32, 34 which sealingly couple to the housing 20 hot and cold water inlets 22, 24 respectively. 
     The hot and cold water inlets 32, 34 receive filter cartridges 36, 38 and are sealed to the housing inlets 22, 24 by o-ring seals 40, 42. A large o-ring seal 44 encircles a disk-shaped front face 46 of mixing cartridge 30 to seal the front face 46 against a mating anterior portion 47 of valve housing 12. The front face 46 has a pair of spaced apertures 48, 50 therein which may be used for gripping the cartridge 30 for insertion and removal from the housing 20. The cartridge puller 10 extends generally axially between a first end which will be referred to as a hook end which clampingly engages the mixing cartridge of 30 and an opposite puller end. 
     Making further reference to FIGS. 3 and 4, the clamping assembly 14 includes a generally cylindrical puller body having a diametrical slot 62 in a hook end thereof and diametrically spaced press pin bores 64, 66 extending axially between an opposite puller end and the slot 62. A pair of diametrically spaced, transverse pivot pin bores 68, 70 receive and support a mating pair of pivot pins 72, 74 respectively which are positioned to extend across the slot 62. 
     The pivot pins 72, 74 operate to pivotally retain a pair of generally L-shaped clamping hooks 76, 78. The clamping hooks 76, 78 have radially outward extending legs 80, 82 which join at interior ends thereof puller ends of axially extending legs 84, 86, respectively. 
     Each axially extending leg has a facing spring retainer protrusion 88, 90 formed therein partway between the two ends and preferably at a location within the notch 62 and terminates in an inward facing bend 92, 94 which forms a small hook 96, 98 respectively. In the present example the clamping hooks 76, 78 are made of spring steel and have a square cross section 1/8&#34; on a side. 
     A spring bias 100 implemented as a small piece of 3/8 inch outside diameter rubber tubing arches between the clamp hooks 76, 78 with its ends engaging the spring retainer protrusions 88, 90. The spring bias 100 tends to maintain the clamp hooks 76, 78 in a spread-apart or release position. 
     The press pin bores 64, 66 receive respectively a pair of press pins 104, 106 having enlarged force bearing surfaces 108, 110 at puller ends thereof. The opposite, hook ends extend through the bores 64, 66 and into force transmitting engagement with the legs 80, 82 respectively. 
     A central, axially extending bore 114 threadedly receives and is securely attached to a hook end of a threaded draw screw 116. The draw screw 116 threadedly receives a clamping nut 120 which, when tightened onto draw screw 116 and into engagement with the force bearing surfaces 108, 110 of press pins 104, 106, pushes press pins 104, 106 axially toward the hook end of puller 10 and causes clamping hooks 76, 78 to rotate about their respective pivot pins 72, 74 and begin to close toward a clamping position. When snugly tightened the clamping nut 120 transmits a clamping force through the press pins 104, 106 to the clamping hooks 76, 78 which is sufficient to securely fasten the clamping hooks 76, 78 to the face 46 of the mixing cartridge 30. The attachment is sufficiently firm and secure to prevent movement of the clamping hooks 76, 78 within the cartridge apertures 48, 50. With movement inhibited, there is no gradual damage to or chipping away of material from the face 46 of mixing cartridge 30. The face 46 thus remains sufficiently strong to withstand even the high pulling forces required to break the sealing engagements between mixing cartridge 30 and valve housing 20 after years of normal operation. 
     In the present example, clamping nut 120 is reinforced by a steel &#34;SURT NUT&#34; hub 122. However, hub 122 is required only when clamping nut 120 is made of a relatively soft material and can normally be omitted by directly boring and tapping clamping nut 120. 
     The slot 62 in the clamping end of puller body 60 is generally rectangular in cross section with a somewhat enlarged rectangular central region 130 for receiving and containing the bias spring 100. The puller end of slot 62 terminates in beveled shoulders 134, 136 which engage the legs 80, 82 of clamping hooks 76, 78 and serve as stops or limits to the opening of clamping hooks 76, 78 under the force of bias spring 130 when clamping nut 120 is released. The shoulders 134, 136 are advantageously located to allow clamping hooks 76, 78 to open sufficiently wide to easily pass through apertures 64, 66 when in the limiting release position. 
     A set screw aperture 140 threadedly receives a set screw 142 which is screwed into engagement with the draw screw 116 to prevent removal of the draw screw 116 from the puller body 60. In addition, a diametric bore 144 slidably receives a stop pin 146 which extends slightly beyond the wall of draw screw 116 to prevent removal of clamping nut 120 from the clamping assembly 14. The bore 144 is located sufficiently distant from the clamping end of draw screw 116 to allow the clamping hooks 76, 78 to attain their full release position. 
     The outer body member 16 comprises a cylindrical outer shell 150 and an end wall 152 which closes the shell 150 and the puller end thereof. The inside diameter and axial length of outer shell 150 are sufficient to enable a central axially extending aperture formed within shell 150 to receive the clamping assembly 14 with a central axially extending aperture 154 in end wall 152 slidably receiving the puller end of draw screw 116 as outer body member 16 is slid over clamping assembly 16. The inside diameter and thickness of outer shell 150 are selected to cause the clamping end thereof to matingly engage a face 158 of valve housing 20 which surrounds an opening 161 through which mixing cartridge 30 is inserted and extracted. 
     Puller nut 18 has a threaded central aperture 160 which threadedly receives the puller end of draw screw 116 after the outer body member 16 has been slid over draw screw 116 and clamping assembly 14. Puller nut 18 has two radially extending arms which are sufficiently long to permit puller nut 160 to be tightened upon draw screw 116 with a relatively high torque. Puller nut 18 cooperates with the puller end of draw screw 116 to provide a force transformation mechanism that is able to provide a mechanical force advantage much greater than one to create relatively high opposed pulling and pushing forces between draw screw 116 and outer body member 16. 
     The pulling force is transmitted through draw screw 116 and clamping hooks 76, 78 of the clamping assembly 14 to cartridge 30 while the equal but opposite pushing force is transmitted through outer body member 16 to valve housing 20. A very high relatively opposed force is thus generated between the cartridge 30 and housing 20 to overcome any sticking of the seals 40, 42, 44 and extract cartridge 30 from the housing 20. 
     In operation, the clamping nut 120 is spun toward the pulling end of draw screw 116 until the clamping hooks 76, 78 open to the release position. This should occur as clamping nut 120 engages stop pin 146. Next, the hooks 96, 98 at the hook ends of clamping hooks 76, 78 are inserted into the apertures 48, 50 in the face 46 of mixing cartridge 30 and clamping nut 120 is spun to close the clamping hooks 76, 78 tightly and securely against interior surfaces of the bores 48, 50. 
     The outer body member 16 is then slid over the draw screw 116 and clamping assembly 14 with aperture 154 receiving draw screw 116 until the clamping end of outer body member 16 engages the face 158 of valve housing 20. The puller nut 18 is then spun onto draw screw 116 and tightened against the end wall 152 until mixing cartridge 30 is withdrawn from valve housing 20. Experience suggests that cartridge 30 must move only a very short distance before the seals are broken and it can be easily removed by a gentle manual pulling force. 
     Referring now to FIG. 5, there is shown a clamping hook 166 of alternative construction to the clamping hooks 76, 78. Clamping hook 166 has a generally right triangle shape with a hook 168 similar to hooks 96, 98 formed in the hook end thereof. A pivot hole 170 for receiving one of the pivot pins 72, 74 is placed near the right angle and a spring retainer protrusion 172 similar to the spring retainer protrusions 88, 90 is disposed along an axially extending leg. The arrangement of FIG. 5 is somewhat stronger than the arrangement of FIGS. 2-4 and facilitates manufacture of the clamping hooks from a material other than spring steel. 
     It will be apparent to a skilled artisan that the cartridge puller 10 can comprise a variety of materials and appear in a variety of different sizes. However, in one particularly advantages configuration the outer body member 16 was made of NYLON, had an outer diameter of 11/4 inch, an inside diameter of 1 inch and an inside bore length of 21/2 inch. The aperture 154 had a diameter of 3/8 inch. 
     The steel draw screw had a 3/8 inch outside diameter, a length of 41/2 inches and a 3/8-16 standard thread. It was tapered at the puller end to facilitate the staring of threading of puller nut 18 thereon. The press pins were made of steel with a length of 3/4 inch and a diameter of 5/32 inch. The spring bias 100 was cut from 3/8 inch rubber tubing with a length of 15/16 inch. The clamping hooks 76, 78 were each 11/8 inch long with a 1/4 inch hook at one end and a 9/16 inch force leg at the other end. The wing nut was made of steel and had two 13/4 inch radially extending arms. 
     The puller body 60 was made of NYLON (although polyvinylchloride or other plastic is contemplated) and had an outside diameter of 17/8 inch and a length of 4 1/32 inch. The slot 62 was 3/8 wide at the center and 3/16 inch wide at the periphery. It was 11/16 deep at the center out to a radius of 3/8 inch and then tapered along beveled shoulders 134, 136 to a depth of 1 inch at the periphery. The pivot pins 72, 74 were 1/8 inch by 1/2 inch long roll pins and were centered at a radius of 1/2 inch and 5/16 inch from the clamping end of puller body 60. 
     The clamping nut 120 was made of NYLON (although polyvinylchloride is contemplated for production quantities) with a diameter of 13/4 inch and an axial length of 1/2 inch. The center is reinforced with a 3/8 inch SURT NUT. 
     While there have been shown and described above various arrangements of a cartridge puller for hot and cold water mixing valves for the purpose of enabling a person skilled in the relevant art to make and use the invention, it should be clear that the invention is not limited thereto. Accordingly, any modifications, variations or equivalent arrangements within the scope of the attached claims should be considered to be within the scope of the invention.