Valves and valve actuation – With correlated flow path – Valve operated by joining flow path sections
Reexamination Certificate
2001-11-09
2003-12-02
Lee, Kevin (Department: 3753)
Valves and valve actuation
With correlated flow path
Valve operated by joining flow path sections
C137S614040, C137S614030, C137S614000
Reexamination Certificate
active
06655656
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to quick disconnect couplings and, more particularly, to a female quick disconnect coupler which provides for quick disconnect and preferably also quick connect.
BACKGROUND OF THE INVENTION
Quick disconnect couplings are used, for example, to connect hoses in hydraulic fluid lines. A typical application is on agricultural tractors to connect the tractor hydraulic system with attachable implements. The tractor typically includes one or more female coupler sockets, while the implements include one or more male coupler nipples. Pneumatic and other applications for such couplings are also well known.
Over the years changes have occurred in these systems which have required changes and performance improvements in the couplings. One early coupling design is shown in U.S. Pat. No. 4,077,433 where the female coupler includes a valve body slidable within the housing and a poppet valve internal to the valve body. The poppet valve is axially movable to engage a check valve in a male coupler when the male coupler is inserted into the female coupler. When low pressure is present in the male coupler, the poppet valve moves the check valve (ball valve) off its valve seat to allow flow from the female coupler to pass to the male coupler. When higher pressures are present in the male coupler, an internal passage in the poppet valve provides incoming fluid pressure to the rear surface of the poppet valve. Due to the differences in effective surface areas, the fluid pressure assists in driving the poppet valve against the check valve to move the check valve into an open position.
An improvement in this coupling is shown in U.S. Pat. No. 4,598,896, where a separate piston is located around the poppet valve. The piston can engage the poppet valve when moved forwardly. An internal passage in the poppet valve provides fluid pressure to the rear surface of the piston, which assists in driving the poppet valve against the check valve in the male coupler in high pressure situations. A spool is also provided around the piston and poppet valve in this coupling. The spool is fixed to the valve body and includes a port for exhausting pressure within the poppet valve. A retainer sleeve with a seal surrounds the port on the spool, and when the valve body slides within the housing (when the male coupler is inserted or removed), the port relieves the internal pressure in the female coupler to atmosphere.
In some cases, particularly when a pair of couplers are used to direct fluid to and from a hydraulic cylinder in an implement, a check valve mechanism is also provided in the female coupler to prevent the rapid backflow of pressure out of the female coupler when a pressure imbalance occurs within the system, such as during thermal expansion of the fluid caused by severe operating conditions, or when the implement is dragged over an uneven surface. In these situations, one of the female couplers can allow the check valve in an associated male coupler to close, which can cause a block in the system when the flow through the female coupler is desired.
To remedy this problem, some female couplers include a check valve mechanism which allows fluid to flow relatively unimpeded rearwardly to the rear surface of the piston, but which restricts or prevents fluid flow forwardly out of the female coupler. One known check valve mechanism includes a valve ball located within the internal bore of the piston which is spring-biased in both directions to allow fluid to flow rearwardly through the piston at a higher flow rate than forwardly through the piston.
The above couplings have received wide-spread acceptance in the marketplace for providing reliable, serviceable and effective components which operate under a variety of conditions. Some of these couplings direct the fluid internally through the poppet valve to the rear surface of the piston. The flow path includes a radial hole formed in the side of the poppet valve, and a central bore extending axially through the poppet valve. A spring is commonly disposed within the central bore of the poppet valve for biasing the poppet valve against the valve seat. As the spring flexes, the spring can interfere with the flow through the radial hole, which can reduce or even temporarily interrupt the flow through the poppet valve. This can cause an uneven driving force of the piston against the poppet valve, which can be undesirable in certain applications.
Towards providing a direct and uninterrupted flow path to the rear surface of the piston to facilitate moving the poppet valve against the check valve in the male coupler, U.S. Pat. No. 6,016,835 discloses a quick disconnect coupling wherein the female coupler includes a housing adapted to receive a male coupler. The housing includes a valve body slidable within the housing, and a poppet valve internal to the valve body. A piston surrounds the poppet valve to assist in moving the poppet valve against the check valve in the male coupler. Unlike prior female couplers, the flow passage to the rear surface of the piston is provided internally of the piston, rather than the poppet valve, which provides a direct and uninterrupted flow path to the rear surface of the piston to facilitate moving the poppet valve against the check valve in the male coupler. In one design, the flow path extends axially through a tubular main portion of the piston closely surrounding the poppet valve to an internal cavity bounded by an enlarged end portion of the piston, and then to the rear surface of the piston. The flow path can be provided through one or more bores formed axially through the tubular main portion of the poppet valve.
According to second design of quick disconnect coupling disclosed in the '835 patent, a check valve is provided to prevent fluid rapidly flowing from the female coupler during pressure imbalances in the system. The check valve includes an annular wiper seal supported on the rear surface of the piston, and projecting radially inward therefrom. A poppet guide and relief poppet assembly is provided in the rear end of the valve body and extends axially forward internally of the piston and poppet valve. The poppet guide and relief poppet assembly includes a circumferential ridge along an exterior surface thereof. The wiper seal on the piston seals against the annular ridge on the assembly when the pressure drops in the female coupler and the piston moves forwardly within the coupler body. In this position, the wiper seal, also referred to as a trap seal, allows fluid to pass only rearward through the female coupler to the rear surface of the piston, and prevents a vacuum in the female coupler from allowing the male check valve to close. The fluid pressure behind the wiper seal is relieved to ambient only during connect and disconnect to allow the piston to move rearwardly.
In the past, the trap seal sometimes would be “blown out” when a surge of pressurized fluid would pass through the trap seal. This obviously negatively impacts the performance of the coupling and may necessitate repair or replacement of the female coupler.
Other problems have been encountered in female couplers which have an axial end port. Heretofore, a spacer has been used in the housing to provide a flow path for pressurized fluid around the piston and also to isolate the pressurized flow path from a vent port. One end of the spacer is supported by a tubular extension of a housing end plug which is threaded into the end of a cylindrical portion of the housing opposite the flow port. The other end of the sleeve is radially supported in the housing at an annular land including an annular seal which seals against the inner diameter surface of the housing. The annular seal separates high pressure flow from the usually zero pressure in the vent port. The high pressure acting on the seal may cause the seal to be extruded between the spacer and housing.
Still another problem area in prior art female couplers has been contamination of the region containing locking balls that lock the male coupler in the female couple
Lee Kevin
Parker Hannifan Corporation
Renner , Otto, Boisselle & Sklar, LLP
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