Liquid purification or separation – Flow – fluid pressure or material level – responsive – Check valve
Reexamination Certificate
2000-05-31
2001-12-11
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Flow, fluid pressure or material level, responsive
Check valve
C210S184000, C210S416400, C210S443000, C137S541000, C123S1960AB
Reexamination Certificate
active
06328883
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to fluid filters, and more particularly to fuel filters for vehicles.
BACKGROUND OF THE INVENTION
Many types of fuel filters (also known as “separators”) are known in the prior art. A popular type of filter construction is a type that has a filter head to which a replaceable “spin-on” element is attached. The head is a permanent part of the fuel system of the vehicle and includes inlet and outlet connections to the fuel lines. The filter element may be readily removed from the filter head and a new one attached without removing the filter head from the fuel line connections.
One problem associated with filters, and particularly filters for diesel fuel, is that during cold starting conditions, the fuel can have a low viscosity—making it difficult for the fuel to pass through the filter. The cold fuel can also wax or plug the filter media. This is a well-known issue, and many devices have been developed in an attempt to solve this. For example, one fuel filter includes a heater provided internally of the filter housing to heat the fuel and the media as the fuel passes through the filter (see, e.g., Stone, U.S. Pat. No. 5,547,572). While such heaters help solve the problem of waxing or plugging, it is believed that many such heaters have been relatively complex assemblies with a number of components that are sometimes difficult to assemble. It is therefore believed there is a need for heaters that are simple to manufacture and assemble, and yet which are still efficient, reliable, and long-lasting.
Another problem is that elements with different efficiencies, applications, and/or qualities can sometimes fit on the same filter head. Periodic replacement of the element is necessary such that the filter element will not become so loaded with impurities that fuel flow is restricted. Replacing the element also ensures that impurities are removed from the fuel before it is delivered to downstream components such as fuel injection pumps and fuel injectors, where such contaminants may cause damage. It is important to replace a spent element with the same type of element. It is also important to run the filter with an element installed. Using the wrong type of element or failing to use any element can allow damage to occur to the downstream components. Certain elements have been designed whereby the element can only fit a certain filter head, and where the filter will not operate without such a filter element installed (see, e.g., Clausen, U.S. Pat. No. 5,643,446). While this has provided some protection, it is believed that there is still a need for simple, compact, easy to assemble elements that can only be used with a specific filter head, and where the filter will not operate without a filter element installed.
A still further problem arises when a fresh element is installed on the filter head. When the spent element is removed, the element is filled with fuel. The fresh element, when it is installed, is not. Therefore, the new element introduces an air pocket into the system. The air pocket may prevent fuel flow if fuel is drawn through the head and element by vacuum produced by a downstream fuel pump. A large slug of air in the system may also cause damage to downstream components such as an injector pump or fuel injectors.
It is known to install a priming pump on the filter head to eliminate the air pocket. The pump is actuated by alternatingly depressing and releasing a pump cap on the filter head. One type of priming pump is located in the fluid flow path between the inlet to the head and the in-flow area of the filter element, with a pair of spherical valve elements controlling the flow of fuel through the head (see, e.g., Jensen, U.S. Pat. No. 5,362,392). This type of pump is reliable, but has flow passages that require careful manufacturing so that the passages are maintained within close tolerances. The passages are also somewhat complicated to manufacture, which adds to the overall cost of the pump. It is therefor believed there is also a need for a filter head with a manual priming pump that is simple to manufacture and assemble, and yet is still reliable.
As such, it is believed there exists a need for an improved filter head, and filter element therefor, that overcomes the drawbacks identified above.
SUMMARY OF THE PRESENT INVENTION
A new and unique fuel filter is provided which includes a filter head and a replaceable filter element. The filter head has an integral priming pump that is simple to manufacture and assemble, and is reliable in operation. The head also has an integral heater that is compact and simple in design and provides efficient, reliable and long-lasting operation. The filter element is simple, compact, and easy to assemble, and can only be used with a specific filter head.
According to a preferred embodiment of the invention, the priming pump of the filter head includes a spring-biased pump cap moveably located over a pump guide. Fluidly-interconnected first, second and third chambers are provided in the filter head, with the pump cap and pump guide forming a portion of the second, intermediate chamber. A first spring-biased check valve is located between the first and second chambers, and permits fuel flow from the inlet of the filter head into the first chamber, and then to the second chamber. A second spring-biased check valve is located between the second and third chambers in the filter head, and allows fuel to flow from the second chamber to the third chamber and then out to the filter element. A heater assembly is received in the third chamber. The fuel is warmed as it passes over the heater assembly and into the filter element.
The heater assembly includes at least one heater plate, and a non-conductive heater pan enclosing the heater plate in the third chamber. The heater pan includes a disk-shaped body and a unitary nipple portion. The nipple portion includes a cylindrical wall extending away from the head and terminating in a radially-inward directed annular portion defining a central opening. A spherical valve member is carried in the nipple portion and spring-biased to a closed position against the central opening. The integral heater is compact and simple in design and provides efficient, reliable and long-lasting operation.
The filter element includes a cylindrical housing enclosing a ring-shaped filter media. The upper end cap of the media includes an annular body portion bonded to one end of the media, and an annular threaded flange portion. The annular flange portion bounds the periphery of the annular body portion, and projects axially upward therefrom. The housing is secured to the media by forming an open end of the housing around the flange portion. A series of holes are formed in the flange portion of the upper end cap, between the threads and the body portion, to allow the fuel to pass radially outward through the flange into a peripheral fuel cavity surrounding the filter media. The filter head includes an annular threaded flange projecting downwardly from the lower surface of the filter head, which cooperates with the flange of the element to allow the element to be screwed onto and off of the filter head. The flange on the filter element carries an O-ring for sealing against the lower surface of the filter head.
The upper end cap of the filter media further has a first annular end cap wall which bounds the inner diameter of the annular body portion, and projects axially inward therefrom. A central portion with fluid passages therethrough transversely spans the annular end cap wall. A central actuating projection extends axially upward from the central portion and is preferably formed unitary with the central portion. The annular end cap wall portion of the end cap accepts the nipple portion when the element is attached to the filter head, with the central actuating projection engaging the spherical valve member of the nipple portion. An annular seal is carried by the upper end cap for sealing against the nipple portion. The element is simple, compact and easy to assemble.
Attachm
Drodge Joseph W.
Hunter Christopher H.
Parker-Hannifin Corporation
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