Electric resistance heating devices – Heating devices – Continuous flow type fluid heater
Reexamination Certificate
2003-10-21
2004-09-21
Campbell, Thor (Department: 3742)
Electric resistance heating devices
Heating devices
Continuous flow type fluid heater
C219S205000
Reexamination Certificate
active
06795646
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates in general to fuel heater elements and the structural design features that are associated with installation and removal of the fuel heater element from a housing. More specifically, the present invention relates to a rod-shaped heater for a fuel-water separator that includes a cam removal feature. As disclosed herein, the cam removal feature includes a cooperation between the fuel heater and a portion of the fuel-water separator housing that facilitates removal of the heater from the housing.
In the field of diesel engine technology, it is not uncommon for diesel fuel to require heating in order to reduce the chances that the fuel will assume a gel-like consistency that would in turn be difficult to deliver and process. Often, a suitable heater is assembled as part of a fuel-water separator to try and eliminate this potential problem. As the fuel is filtered, water and particulate are separated and collected for removal. Since such a filter/separator may be used in low temperature conditions, though not continuously, the fuel heater is controlled by a thermostat that monitors the fuel temperature and is set to activate at a preset temperature, such as 35° F. When the fuel heater is energized, it generates a beat increase to the interior of the housing. This in turn liquefies any gelled fuel, allowing the fuel to flow freely.
While there are a variety of heater designs that are currently available or have been offered for use in fuel-water separators, a couple of the more common styles can be improved upon and are improved upon by the present invention. One such prior style is a ring heater that is installed into the filter/separator housing and is captured by its manner of insertion and attachment and/or by use of the closing lid. Ring heaters of the type described are relatively complex in construction and necessitate a fairly complex cooperating configuration within the filter housing. There may be added complexity, depending on the selected configuration and the interconnect with the thermostat and the electrical power connector.
One attempt to simplify the complexity of the ring heater is represented by the second prior style that can best be described as a rod heater. This descriptive name comes from the generally cylindrical shape of the fuel heater. This style of heater is typically threaded into a receiving bore in the fuel-water separator. Since there is fuel inside of the housing and since there is an internal pressure, it is important to adequately seal the interface between the heater and the separator housing. If a plastic housing is used, concerns have been raised as to whether sufficient tightening torque can be applied by way of the threaded engagement to adequately seal the threaded interface.
Another concern with a threaded engagement between the rod heater and the separator housing is the ability to establish the desired orientation for the electrical connector on the fuel heater relative to the housing. Over tightening or under tightening of the threaded engagement will cause the rotational position or orientation of the electrical connector to change. The starting point of the threaded engagement can also affect the orientation of the electrical connector. As such, the fuel heater may not be rotated into the preferred location for electrical connection to the heater wires from the wiring harness of the corresponding engine. It would therefore be an improvement if the heater could be installed in the housing with an automatic alignment capability. The present invention provides this improvement without relying on a threaded engagement between the heater and the fuel-water separator housing.
One of the realities of installing a rod heater into a fuel-water separator housing is the need to include a seal, such as an elastomeric O-ring seal, for establishing a sealed interface between the heater and the housing. Over time, the O-ring seal swells in size and becomes even tighter, tighter to the extent that it is difficult to break the O-ring seal free in order for removal of the heater. The effect of this O-ring seal swelling is to wedge the fuel heater into the separator housing to the point that the heater appears to be stuck and, as a result, not easily removed from the housing.
The present invention addresses this concern in a novel and unobvious way by creating a cooperating cam engagement between the fuel heater and the fuel-water separator housing. This cam action translates rotational motion of the fuel heater relative to the housing into an axial force to help break away the tightly wedged O-ring seal. Once the wedged seal is broken free, the fuel heater can be easily removed without the need for any special removal tool and without the risk of damaging the fuel heater. The fuel heater can be removed by hand and this provides yet another benefit attributable to the present invention.
SUMMARY OF THE INVENTION
The combination of a fuel filter housing and a fuel heater according to one embodiment of the present invention includes a heater-receiving bore and a notch opening into the bore as part of the fuel filter housing. The fuel heater is constructed and arranged for inserting into the heater-receiving bore and for being attached to the fuel filter housing. The fuel heater includes a protrusion that is constructed and arranged for engaging the notch such that turning the fuel heater causes the protrusion to cooperate with a ramp portion of the notch in order to facilitate removal of the fuel heater from the heater-receiving bore by a camming action.
One object of the present invention is to provide an improved installation interface between a fuel filter housing and a fuel heater to facilitate removal of the fuel heater from the fuel filter housing.
Related objects and advantages of the present invention will be apparent from the following description.
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Bagci Ismail C.
Wieczorek Mark T.
Campbell Thor
Fleetguard Inc.
Woodard Emhardt Moriarty McNett & Henry LLP
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