Imported: 02 Mar '17 | Published: 26 May '09
USPTO - Utility Patents
The present invention provides an actuated gate valve including a gate valve housing and an actuating device attached to one end of the gate valve housing. The gate valve housing includes a displaceable valve plate, and the actuating device includes an actuator rod connected to the valve plate so that a force applied to the valve plate by the actuator rod is coincident with a displacement of the valve plate.
This application claims the benefit of U.S. Provisional Application No. 60/673,381, filed Apr. 21, 2005, which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to valves. More particularly, the present invention relates to actuated gate valves.
2. Description of Related Art
Gate valves are used to stop the flow of fluid in a tube or pipe. Typically, gate valves can handle material similar to the viscosity of water, or higher, as well as material that is in a vacuum or under small levels of pressure.
An exemplary prior art gate valve 100 is depicted in FIG. 1. An activation device 105, such as a pneumatic valve, is attached to the back side of a valve assembly frame 110 and transmits opening and closing forces to a valve plate 115, located on the front side of the valve assembly frame 110, using an actuator rod 125 coupled to a link 120 connected to an intermediate stem 155. A sealed housing 135 encloses the valve plate 115, and includes a coupling 130 through which the intermediate stem 155 passes. A piping interface plate 140, located on the front side of the housing 135, connects to a piping system (not shown), while another piping interface plate 142, located on the back side of the housing 135, attaches the housing 135 to the valve assembly frame 110. The piping interface plate 141 is coupled to the piping system (not shown) through an opening in the valve assembly frame 110. An additional piping interface plate (not shown) may also be attached to the back side of the valve assembly frame 110.
If the link 120 is connected directly to the intermediate stem 155 (not shown), an undesirable torque is applied to the intermediate stem 155 due to the misalignment of the line of action of the force applied by the activation device 105 and the centerline of the intermediate stern 155. This torque produces undesirable stresses in the intermediate stern 155 and the valve plate 115, as well as misalignments among the various components.
In order to reduce the effects of these undesirable stresses and misalignments, a spring assembly 150 can be incorporated into the gate valve 100 (shown), The spring assembly 150 includes upper and lower nuts 152, 154, attached to the intermediate stem 155, and upper and lower springs 156, 158, acting between the upper and lower surfaces of the link 120 and the upper and lower nuts 152, 154, respectively. Forces applied by the link 120 to the spring assembly 150 are transmitted to the intermediate stem 155 through the upper and lower nuts 152, 154, while misalignment of the Intermediate stern 155 is reduced due to the transverse flexibility of the spring assembly 150 and the freedom of movement afforded by the simple, contact interfaces between the upper and lower surfaces of the link 120 and the upper and lower springs 156, 158, respectively, as well as between the upper and lower springs 156, 158, the upper and lower nuts 152, 154, respectively.
However, the prior art gate valve 100 is mechanically complex, the undesirable stresses and misalignments have not been entirely eliminated and the upper and lower springs 156, 158 can limit the force that can be applied by the activation device 105 to the valve plate 115, resulting in unsatisfactory performance in many situations. Therefore, there is a need for an actuated gate valve that does not suffer from these infirmities.
Embodiments of the present invention provide an actuated gate valve including a gate valve housing and an actuating device attached to one end of the gate valve housing, The gate valve housing includes a displaceable valve plate, and the actuating device includes an actuator rod connected to the valve plate so that a force applied to the valve plate by the actuator rod is coincident with a displacement of the valve plate.
FIGS. 2 and 3 depict a gate valve 200 in accordance with an embodiment of the present invention.
The gate valve 200 includes an activation device 205 which is attached to one end of a sealed housing 235. In a preferred embodiment, the activation device 205 may be a double-acting hydraulic or pneumatic cylinder 205 that includes activation fluid couplings 206, 207, while in other embodiments, the activation device 205 may be an electric actuator, an electric motor, etc. The cylinder 205 includes an interface plate 208, which is attached to an actuator interface plate 236 of housing 235 using, for example, bolts 209 and nuts 239, welds or weldments, etc. A gasket may be interposed between interface plates 208 and 236, if necessary. The source of the activation fluid may be, for example, a hydraulic system on the vehicle on which the gate valve 200 is mounted, etc. In a preferred embodiment, cylinder 205 operates under a pressure range of about 1,500 to 3,000 psi.
In the preferred embodiment, the double-acting cylinder 205 advantageously provides a direct closing force of up to 4000 pounds in order to clear any small obstructions in the gate valve 200, such as, for example, sand, straw, sediment, etc. Furthermore, a closing force of this magnitude ensures complete closure of the valve plate 215, which is depicted in an open position in FIG. 2, and in a closed position in FIG. 3. The gate valve 200 may also regulate the fluid flow by positioning valve plate 215 in a partially open (or partially dosed) position.
The cylinder 205 hosts an actuator rod 225 attached to the valve plate 215 using, for example, a pin 226 passing through holes 227, 228 in the actuator rod 225 and valve plate 215, respectively. The direct, in-line connection of the actuator rod 225 to the valve plate 215 provides several advantages over the prior art. For example, the link 120, the intermediate stem 155 and the spring assembly 150 (shown in FIG. 1) are not required, thereby completely eliminating the undesirable stresses and misalignments attendant to prior art devices. Commensurately, the coupling 130 is also eliminated, thereby eliminating the need for stem packing or some other form of seal at the top of the housing 135.
In one embodiment, the gate valve 200 is made of stainless steel, and housing 235 may be cast or machined as two identical parts, such as a front housing 235f with a front actuator interface plate 236F, and a back housing 235b with a back actuator interface plate 236b. Front and back housings 235f, 235b may be attached together using, for example, bolts 238 and nuts 239, welds or weldments, etc. A gasket may be interposed between front and back housings 235f, 235b, if necessary. A cylindrical cavity 246f, 246b is formed In each housing 235f, 235b to permit the actuator rod 225 to move the valve plate 215 in a vertical direction (labeled displacement) within the main cavity 244f, 244b. An additional cutout region, 245f, 245b may also be formed within each housing 235f, 235b to hold grease or other material to help seal and lubricate the valve, as well as to provide a cavity in which undesirable foreign material may be captured so as to prevent the valve plate 215 from pinching at the top of the main cavity 244f, 244b.
A front piping interface plate 240f, located on the front housing 235f, is connected to the piping system (not shown), while a back piping interface plate 240b (not visible), located on the back housing 235b, is similarly connected. Piping interface plates 240f, 240b include openings 242f, 242b for fluid inlet and outlet.
Accordingly, the gate valve 200 presents several advantages over the prior art devices, such as eliminating the necessity of assembling two halves of the gate valve and then drilling and tapping the assembly to provide a cavity for the seal packing and nut. These advantages simplify the manufacturing processes, improve performance and promote better reliability in the field.
FIG. 4 presents an application of the present invention in accordance with an embodiment thereof. For example, one application of the gate valve 200 would be on a liquid waste-handling tank 300 to stop the flow to a discharge pipe. Other applications may include liquid waste pumps, generally, as well as pumping systems in which an in-line, shut-off valve is needed but in which small debris pose a challenge for standard gate valves.
While this invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth herein, are intended to be illustrative, not limiting. Various changes may be made without departing from the true spirit and full scope of the invention as set forth herein.