Liquid purification or separation – Filter – With pump – gas pressure – or suction source
Reexamination Certificate
2001-03-30
2003-04-29
Savage, Matthew O. (Department: 1723)
Liquid purification or separation
Filter
With pump, gas pressure, or suction source
C210S418000, C210S450000, C210S456000
Reexamination Certificate
active
06555000
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 referred to as “separators”) are known in the prior art. A popular type of fuel filter has a housing that encloses a replaceable ring-shaped filter element. The filter element ensures that impurities are removed from fuel before it is delivered to system components such as fuel injection pumps and fuel injectors. Mating portions of the housing form an interior enclosure for the element, and the housing portions may be separated for replacement of a spent filter element. Periodic replacement of the filter element is required so that the filter element will not become so loaded with impurities that fuel flow is restricted. Cost and ease of manufacture have been important considerations with such elements. However, problems may arise when such filter elements are replaced.
One problem is that filter elements with different sizes and/or filtration capabilities often have identical mounting configurations and can fit on the same filter head. However, use of the wrong filter can cause poor engine performance and allow undesirable amounts of contaminants to pass through the fuel system.
Another problem is that individuals may remove a spent filter element and simply re-attach the housing portions without a fresh element. While the engine may operate (at least for a short period of time), this can be detrimental to the engine.
A still further problem is that disturbance of the spent element during replacement may cause collected impurities to fall off the element. In some designs, these impurities may pass into the outlet of the filter housing and reach the components downstream in the fuel system.
To reduce and at least partially eliminate these problems, the filter assembly shown in U.S. Pat. No. 4,836,923, owned by the Assignee of the present application, was developed. This filter includes a unique replaceable filter element that is attached to a removable cover. The housing has an internal standpipe with an opening at the top end. When the element is removed from the housing, the fuel level in the housing falls below the opening in the standpipe. As a result, the impurity-laden fuel left in the housing is less likely to reach the outlet. Likewise, when a new element is installed in the housing, only fuel that has been purified by passing through the media of the element is enabled to reach the opening and pass out of the housing.
While this filter design has many advantages, if the filter element is not removed carefully, impurity-laden fuel in the housing or from the outer surface of the element may fall into the opening in the standpipe. If this happens, some impurities may still reach the downstream components of the fuel system.
In addition, the cover is discarded with each spent element. This is undesirable from a conservation and solid waste standpoint. It is generally desirable to minimize the amount of material discarded, particularly if a discarded element must be treated as hazardous waste. The cover also represents a portion of the cost of the replacement element. As a result this design adds cost to the replacement element. Further, the element may be separated from the cover, and the cover re-attached to the housing without a fresh element also being installed. As such, it still does not fully address the problems associated with operating an engine without a filter element installed.
A further improved filter is shown in U.S. Pat. No. 5,770,065, also owned by the assignee of the present application. In this filter, the filter element is received around a standpipe extending centrally in the housing. A spring-biased valve element internal to the standpipe is normally closed, and can be engaged and moved to an open position by a projection on the element when the element is properly installed in the housing. This filter provides the advantages of the '923 patent, as well as prevents impurity-laden fuel from passing through the standpipe when the element is changed. The assembly also prevents operation of the engine without an appropriate element in place.
The filter shown in the '065 patent has received wide-spread acceptance in the marketplace. Nevertheless, it is believed that there exists a need for a still further filter which has the advantages of the '065 patent, but where the valve structure is located exterior to the standpipe. Such a valve structure can be easier to manufacture and assemble, thereby reducing the cost of the assembly. It is also believed there is a demand for a filter where the opening into the standpipe is located toward the lower end of the filter. This can prevent or at least reduce the chance of pulling air into the system, as the opening is kept below the level of the fuel.
A still further issue with fuel filters, and particularly those filters including a fuel pump which forces fluid through the filter to facilitate the transfer of fuel through the fuel system, is that the flow path through the filter is typically interrupted if the pump is not operating. This is because the gears, and/or other components within the pump typically prevent fuel flow through the pump when they are not moving. If the pump is broken, or if a short occurs in the electronic system, the engine can be stall. As such, it is believed there is also a demand for a filter including a fuel pump, where a flow path is maintained through the fuel system even when the pump is not operating.
As such, it is believed that there exists a need for a further improved fuel filter which overcomes at least some of the above-described drawbacks.
SUMMARY OF THE PRESENT INVENTION
A new and unique fuel filter is provided that prevents an improper filter element from being used in the filter and prevents operation of the filter without a filter element in place. The filter is simple and low-cost to manufacture and assemble, and prevents air from entering the system. The filter also maintains a flow path through the fuel system when the fuel pump is not operating.
According to the present invention, a pipe extends centrally within the housing, and a valve structure is provided externally to the pipe. In one embodiment, the pipe is a standpipe fluidly connected to the outlet port; while in another embodiment the pipe is an inlet pipe to a fuel pump in the housing. In either embodiment, the pipe includes a central fluid passage and an opening into the passage toward the lower end of the pipe. A radially-outward facing groove or channel is provided circumferentially around the pipe, near the opening.
The valve structure for the filter includes a valve device and a latch device. The valve device has a sleeve closely surrounding the pipe, and an annular, radially-outward projecting base surrounding the sleeve. A series of radially-outward projecting tabs are spaced around the periphery of the base. The valve device can be easily manufactured unitarily in one piece from inexpensive material, such as plastic.
The latch device for the valve structure includes a series of deformable fingers in an annular array closely surrounding the pipe. The distal ends of the fingers are normally aligned with and engage the groove in the pipe to prevent the latch device from moving axially along the pipe. The latch device, in the locked position, supports the valve device in a position such that the valve sleeve blocks flow through the opening in the pipe. The latch device further includes an annular sleeve radially outwardly-spaced from the fingers. One end of the sleeve, located away from the valve device, is connected to the fingers, while the other end of the sleeve, located adjacent the valve device, defines an annular engagement surface. The latch device likewise can be easily manufactured in one piece from inexpensive material, such as plastic.
According to the first embodiment, the housing is designed for a “top-loaded” element, and includes a removable lid. In this embodiment, the latch device is located betwee
Hunter Christopher H.
Parker-Hannifin Corporation
Savage Matthew O.
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