Fluid handling – Line condition change responsive valves – Bi-directional flow valves
Reexamination Certificate
2000-07-10
2001-04-17
Chambers, A. Michael (Department: 3753)
Fluid handling
Line condition change responsive valves
Bi-directional flow valves
Reexamination Certificate
active
06216729
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to mechanical valves and, more particularly, to check valves that prevent the movement of fluids in a hydraulic system when the pressure of the fluid is less than a predetermined value.
BACKGROUND OF THE INVENTION
Conventional check valves permit liquids or gases to flow in only one direction. Such check valves are present in hydraulic systems, typically in mobile and fixed equipment, to control the flow path of fluids in the system. Check valves are also used in a variety of pumps to prevent the backward flow of liquids.
The hydraulic system is typically connected to other, auxiliary systems that may share a common fluid path with the hydraulic system. When a leak or hose failure occurs in the hydraulic system, fluid may also leak from the other systems that are connected to the hydraulic system and result in further fluid loss as well as cause the auxiliary systems to fail.
It is therefore desirable to prevent the loss of fluid from the auxiliary systems when a fluid is lost from the hydraulic system.
Further, fluid losses in the hydraulic system may be exacerbated by the auxiliary systems. When, for example, there is a back pressure from the auxiliary systems, pressurized fluid reservoirs or the like, the fluid pressure from the auxiliary systems aggravate any leaks present in the hydraulic system.
Also, when there is valve leakage from the auxiliary systems, fluid will also be lost from the hydraulic system.
Thus, there is also a need to automatically isolate the hydraulic system from the accessory systems to further fluid loss when there is a leak in either the hydraulic system or in an auxiliary system.
SUMMARY OF THE INVENTION
The present invention provides a bidirectional check valve that blocks the flow of fluid in a given direction when the fluid pressure in that direction falls below a predetermined value.
According to an aspect of the invention, a bidirectional check valve controls movement of fluid. A valve body has at least an opening and a further opening therein and has a passage connecting the opening and the further opening. A poppet is disposed within the passage of the valve body and is arranged such that at least a portion of an outer surface of the poppet and at least a portion of a wall of the passage of the valve body define at least one channel. The poppet has at least an opening therein in proximity to the opening in the valve body and has a passage connecting to the opening in the poppet. A spring is coupled to the poppet. The spring is arranged to drive the poppet in a direction such that when fluid passing through the opening in the valve body exerts a force on the poppet that is less than the spring force, a further portion of the outer surface of the poppet contacts a further portion of the passage wall of the valve body and prevents the fluid from flowing from the opening in the valve body into the channel. When the fluid exerts a force on the poppet that is greater than the spring force, the poppet is directed away from the further portion of the passage wall and permits the fluid to flow from the opening in the valve body through the channel and to the further opening in the valve body. A further poppet is disposed within the passage formed in the first mentioned poppet. The further spring is arranged such that at least a portion of an outer surface of the further poppet and at least a portion of a passage wall of the poppet define at least one further channel. The outer surface of the further poppet has at least an opening therein that connects to a passage formed within the further poppet. The passage within the further poppet connects to a further opening in the further poppet that is in proximity to the opening in the poppet. A further spring is coupled to the poppet and to the further poppet. The further spring is arranged to drive the further poppet in a further direction such that when fluid passing through the further opening in the valve body exerts a force on the further poppet that is less than the further spring force, a further portion of the outer surface of the further poppet blocks the further channel and prevents the fluid from flowing from the further opening in the valve body into the further channel. When the fluid exerts a force on the further poppet that is greater than the further spring force, the further portion of the outer surface of the further poppet is directed away from the further opening in the valve body to open the further channel and permit the fluid to flow from the further opening in the valve body through the further channel, the, at least, one opening in the further poppet, the further passage in the further poppet, the further opening in the further poppet and the opening in the poppet to the opening of the valve body.
According to another aspect of the invention, a hydraulic apparatus includes one or more supply lines, one or more return lines, a pump configured to drive fluid through the supply line at a supply pressure, and a flow component disposed between the supply line and the return line and providing a pressure differential in the fluid such that a return pressure in the return line is less than the supply pressure. The bidirectional check valve is disposed within the supply line and/or the return line.
Other features and advantages of the present invention will become apparent from the following detailed description of the invention with reference to the accompanying drawings.
REFERENCES:
patent: 4993921 (1991-02-01), Taplin et al.
patent: 5048561 (1991-09-01), Taplin et al.
patent: 6000417 (1999-12-01), Jacobs
Hambly Hugh
Thornton Brian
Chambers A. Michael
Cobrin & Gittes
McShane Thomas L.
Parsons & Whittemore, Inc.
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