# Patent

## Title
Flush valve

## Abstract

A flush valve has a valve body having an inlet and an outlet, and a piston disposed in the valve body between the inlet and said outlet to regulate flow through the valve body. The piston has a shoulder. A neck depends from the shoulder and has a smaller perimeter than the shoulder. And, a flange depends from the neck and has a larger perimeter than the neck. Better flow characteristics of fluid about the shoulder, neck, and flange minimize noise coming from the valve and increase reliability thereof.

## Background
RELATED APPLICATION
This application claims priority to U.S. Provisional Application No. 61/314,733, which was filed on Mar. 17, 2010.


BACKGROUND OF THE INVENTION
Flush valves may have a handle that, when manipulated, pushes an actuator which, in turn, opens a bypass valve within a piston in the flush valve. By opening the bypass valve, pressure above the piston drops and allows line pressure to lift the piston from its seat within the flush valve and channel water to flush a toilet, urinal or the like. While the toilet or urinal fixture is being flushed, line pressure is also directed above the piston increasing the pressure in this area. As the pressure equalizes the piston seats itself within the flush valve and stops flow therethrough.
Commercial flush valves sometimes experience problems such as water hammer and failure to shut off. Water hammer may occur if water in motion is forced to stop or change direction suddenly. This rapid change in momentum creates a surge in pressure and results in shock waves that propagate through the piping making noise. Some plumbing codes require flush valves to have anti-backflow devices like a vacuum breaker to prevent fouling of the potable water supply in the event of backflow from the toilet or urinal fixture into the valve and the related water supply.
SUMMARY OF THE INVENTION
A flush valve has a valve body having an inlet and an outlet, and a piston disposed in the valve body between the inlet and said outlet to regulate flow through the valve body. The piston has a shoulder. A neck depends from the shoulder and has a smaller perimeter than the shoulder. And, a flange depends from the neck and has a larger perimeter than the neck. Better flow characteristics of fluid about the shoulder, neck, and flange minimize noise coming from the valve and increase reliability thereof.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective cutaway view of the flush valve of the invention.
FIG. 2 is a perspective view of the valve of FIG. 1.
FIG. 3 is a side view of the piston body of FIG. 2.
FIG. 4 is a perspective view of the piston cap of FIG. 2.
FIG. 4A is a top view of the piston cap of FIG. 4.
FIG. 5 is a perspective view of the anti-backflow prevention device of FIG. 1.
FIG. 5A is a perspective view of an alternate embodiment of the anti-backflow cartridge of FIG. 1.



DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, the flush valve 10 of the invention is shown. The flush valve 10 has a valve assembly 15, an actuator assembly 20 (as in known in the art), an anti-back flow cartridge 30 and a discharge tube 35 that disgorges water into a toilet or urinal (not shown) or the like.
Referring now to FIGS. 2 and 3, the valve assembly 15 has an inlet 40 disposed in a valve body 45, a piston 50 operating in the valve body 45, a piston cap 55 and an outlet 60 disposed in the valve body. The piston 50 comprises a piston guide 65, a piston body 70, an o-ring 75, a bypass seal 80, an actuator 85, a collar 90, a bypass valve 95, a spring 100, a cap 105, and a wiper seal 110.
The piston guide 65 has a tapered interior 115, a circular cutout 120 for holding the o-ring 75, a shoulder 125 for mounting the bypass seal 80 and threads 130 for mating with the threaded piston body interior 135. An extended portion 142 of the piston guide 65 extends beyond a tapered portion 140 of the valve body 45 if the piston 50 is seated.
The piston body 70 has a lower cutout 145 for holding the o-ring 75 and an interior ledge 150 for holding the bypass seal 80. The shoulder 125 of the piston guide 65 and the interior ledge 150 of the piston body 70 position the bypass seal 80 therebetween. Similarly, the circular cutout 120 of the piston guide 65 and the lower cutout 145 of the piston body trap the o-ring 75 therebetween.
The o-ring 75 seats the piston 50 on the tapered portion 140 of the valve body 45. In this embodiment, the tapered portion of the valve body 45 has a length of 0.125 inches and is disposed at an angle of 20° relative to the outlet 60, though other angles and lengths are possible for other valves.
The bypass valve 95, which seats on the bypass seal 80, has a threaded interior 155 for receiving the threaded portion 160 of the actuator 85. The actuator is attached to the collar 90 that interacts with the actuator assembly 20 (see also FIG. 1) to move/tilt the bypass valve 95 off of the bypass seal 80 as will be discussed herein.
The cap 105, which is circular, has a central opening 165 therein, and a set of downwardly depending threads 170 that attach to a set of interior threads 175 in the piston body 70 (shown in FIG. 3). The cap 105 seats the spring 100 between it and the bypass valve 95. The cap also fixes the wiper seal 110 between it and an outer ledge 180 in the piston body.
The piston 50 moves upwardly and downwardly within the valve body 45 and within the piston cap 55, which is conventionally fixed for easy access within the valve body 45. An area 185 for holding fluid is defined in the piston cap 55 above the piston 50. The wiper seal 110 extends beyond the edges of the outer ledge 180 to form an interference fit with an interior wall 190 of the piston cap 55 (see also FIG. 4) as will be discussed herein.
Referring to FIG. 3, the piston body 70 is shown. The piston body 70 has a neck 200, a body portion 205 having a larger perimeter than the neck 200, and a shoulder 210 having a rounded portion 220 and a larger perimeter than the neck 200. The body portion 205 has a piston body taper 225 therein that slopes inwardly towards the neck 200. In the embodiment shown herein, the taper 225 is disposed at an angle of approximately 200 relative to the perimeter of the body portion 205 and has a length of approximately 0.168 inches. The rounded portion 220 of the shoulder 210 has a radius of approximately 0.04 inches. Other combinations and permutations of radius, angle and length may be used in other valves if they provide the benefits of this invention.
Referring to FIGS. 4 and 4a, the piston cap 55 is shown having, in the embodiment shown, a groove 230 having a depth of approximately 0.006 inches and a 0 of about 0.040 inches disposed in the inner wall 190. The groove 230 extends from a bottom 235 of the piston cap 55 to a top 240 thereof to communicate fluid from the valve inlet 40 to an area 185 above the cap 105. The shape of the groove 230 minimizes a possibility that debris (not shown) might get stuck in or clog the groove 230. The groove 230 is further sized to allow fluid to equalize above the piston 50 to seat the piston 50 as will be discussed herein while allowing enough fluid to pass by the wiper seal 110 to achieve an adequate flushing function. If the groove 230 is too small in area, the valve 15 will be open too long and if too large in area, too short.
Before the valve 15 is operated, pressure is equalized between the area 185 within the piston cap 55 above the piston 50 and line pressure in the plumbing system (not shown) within the inlet 40. Pressure in the outlet 60 is low as fluid has been disgorged therethrough. During operation of the piston 50, if the actuator assembly 20 is manipulated, the collar 90 is tilted and the actuator 85 attached thereto tips the bypass valve 95 off the bypass seal 80 against the force of the spring 100 to allow fluid to flow from the area 185 above the piston 50 thereby lowering the pressure therein. Line pressure in the inlet 40 therefore pushes the piston 50 off the tapered portion 140 within the valve body 45 to allow fluid to flow past the neck 200 of the piston body 70, the o-ring 75, the extended portion 142 of the piston guide 65, the rounded portion 220 of the piston body shoulder 210, and the piston body taper 225 that slopes inwardly towards the neck 200, to exit the valve 15.
As the valve 15 operates, inlet fluid flows through the groove 230, bypassing the wiper seal 110, gradually allowing pressure in the area 185 above the piston 50 to equalize with the line pressure thereby gradually moving the piston 50 down along the inner wall 190 of the piston cap 55 until o-ring 75 seals against the tapered portion 140 of the valve body 45. As the piston 50 moves, the wiper seal 110 tends to remove debris that might clog or block fluid from flowing in the groove 230 in the piston cap 55.
The extended portion 142 of the piston guide 65, in conjunction with the o-ring 75 and the tapered portion 140 of the valve body 45, helps to create a funnel to minimize turbulent flow from the valve 15 as the piston 50 seats on the tapered portion 140 of the housing 45 thereby minimizing water hammer. Similarly, the piston body taper 225 and the rounded portion 220 of the piston body 70, collectively and individually, smooth flow around the piston body also minimizing the effects of water hammer in the valve 15. Additionally, the neck 200 of the piston body 70 allows inlet pressure to be more equally distributed therearound thereby centering the piston 50 more efficiently thereby easing translation of the piston 50 in the piston cap 55 and extending valve life.
Referring now to FIGS. 1, 5, and 5a, the anti-backflow cartridge 30 is shown. The cartridge has a tubular housing 250 that slips into the discharge tube 35. The tubular housing has a lip 255 that prevents the housing from slipping down into the discharge tube thereby giving a user easy access to the cartridge if maintenance is required. A pair of anti-backflow check valves 260, manufactured by Neoperl, are arranged in series in the tubular housing and each are held therein the tubular housing 250. The anti-backflow valves provide enough resistance to minimize backflow while allowing enough flow to maximize the use of the toilet or urinal. The o-rings 265 also prevent fluid from flowing around each anti-backflow check valve back to the valve assembly 10. A flange 280 may depend inwardly at a bottom of said tubular housing 250.
In an alternative embodiment shown in FIG. 1, the tubular housing 250 is the discharge tube 35 and if the cartridge 30 needs replacement, the discharge tube 35 is replaced therewith. The discharge tube 35 has a set of threads 255 therearound for mating with the threads 285 of the valve body 45.
Each anti-backflow valve 260 prevents fluid from flowing up from the toilet or urinal (not shown) so that neither the water supply nor the valve assembly 15 is contaminated by the fluid. The anti-backflow valves replace vacuum breakers (not shown) and also have a much longer life than a typical prior art vacuum breaker.
The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. For instance, one of ordinary skill in the art will recognize that other designs such as objects, abstracts, architectural features may be substituted for the designs shown herein. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.

## Claims

1. A flush valve, said flush valve comprising:
a valve body having an inlet and an outlet;
a piston disposed in said valve body between said inlet and said outlet, said piston configured to move along an axis defined by said outlet, said piston comprising:
a body portion;
a neck depending from said body portion, said neck having a smaller outer perimeter than an outer perimeter of said body portion;
a shoulder depending from said neck, said shoulder having a larger outer perimeter than the outer perimeter of said neck, wherein flow of fluid about said body portion, neck and shoulder minimizes water hammer as fluid flows from said inlet to said outlet;
a seal seated on said shoulder;
an outer piston cap defining a cavity configured to receive a portion of said piston, said outer piston cap defining a groove formed in a surface of said cavity, and wherein said groove provides a flow path between said inlet and an area in said cavity about said piston;
said piston including an inner piston cap attached to said piston body, wherein said inner piston cap provides a flow path between said cavity and a cutout defined by said piston body; and
a bypass valve with a spring seated between said inner piston cap and said bypass valve, wherein said bypass valve is operable to minimize fluid flow between said cavity and said cutout.

2. The piston of claim 1 wherein said body portion further comprises:
a tapering portion that tapers inwardly from said body portion towards said neck.

3. The piston of claim 2 wherein said tapering portion has a length of approximately 0.168 inches.

4. The piston of claim 2 wherein said tapering portion is disposed at an angle of approximately 20° relative to a portion of said body portion.

5. The piston of claim 1 wherein said shoulder further comprises:
a rounded portion disposed on an outer periphery thereof.

6. The piston of claim 1 wherein said body portion further comprises:
a ledge extending radially inwardly from the outer perimeter of said body portion; and
a wiper seal disposed on said ledge.

7. The flush valve of claim 1 wherein said valve body further comprises:
a surface for seating said shoulder thereupon.

8. The flush valve of claim 7, wherein said surface tapers inwardly towards said outlet of said valve body.

9. The flush valve of claim 1, wherein said shoulder seats said seal upon an inner peripheral surface thereof.

10. The flush valve of claim 9, wherein said valve body defines a surface disposed between said inlet and said outlet, wherein said surface is configured to selectively contact said seal to minimize fluid flow between said inlet and said outlet.

11. The flush valve of claim 10 wherein said surface of said valve body tapers inwardly towards said outlet of said valve body.

12. The flush valve of claim 1, wherein said neck is in fluid communication with said inlet when said piston is located in a closed position.

13. The flush valve of claim 1, comprising a second seal configured to form an interference fit between said piston and an interior wall of said outer piston cap.

14. The flush valve of claim 13, wherein said second seal is disposed adjacent to said groove.

15. The flush valve of claim 13, wherein said second seal is configured to move relative to said groove.

16. The flush valve of claim 13, wherein said second seal is a wiper seal.

17. The flush valve of claim 1, wherein said cutout is in fluid communication with said outlet.

18. The flush valve of claim 1, wherein said piston extends from a first end to a second end, said shoulder comprises said second end, and wherein said seal is fixed to said shoulder such that at least a portion of said seal extends outwardly of said second end of said piston to selectively engage a surface of said valve body.

19. The flush valve of claim 18, wherein said shoulder includes an inner peripheral surface that receives said seal.

20. The flush valve of claim 19, wherein said surface of said valve body comprises a tapered surface.

21. The flush valve of claim 20, including a piston guide extending outwardly from the second end of said piston, said seal being located radially between said piston guide and said shoulder.