Bracket for mounting a crankcase heater

A compressor crankcase heater bracket and method of assembly is shown in which a bracket fastened to the compressor accommodates a metal spring clip holding the heater. The method of assembly results in a quick and easy assembly process without compromising the integrity of the transfer of heat to the housing. Thermal transfer is further aided by conduction through the clip and bracket.

BACKGROUND OF THE INVENTION 
The present invention relates to compressor heaters and more particularly, 
to a bracket design and method of assembly for a compressor crankcase 
heater. 
In closed loop refrigeration systems, a compressor pumps refrigerant 
through an evaporator and condenser to provide cooling or refrigeration. 
The refrigerant cycles through the system to return into the compressor to 
cycle again. When refrigerant enters the compressor, it is desirable to 
maintain the refrigerant in a gaseous state during its time within the 
compressor. Since refrigerant is heavier than lubricant, liquid 
refrigerant could accumulate in the compressor sump, mixing with and 
diluting the lubricant, thereby reducing the effectiveness of the 
lubrication. 
The refrigerant may, in liquid form, migrate from the condenser into the 
compressor crankcase oil sump. During start up of the compressor, the 
sudden reduction in crankcase pressure may cause the refrigerant to boil, 
thus causing the lubricant to foam with consequent loss of lubrication to 
other mechanical parts of the compressor. 
Even if the refrigerant is in a gaseous state when returning to the 
compressor, a lower temperature in the compressor could condense the 
refrigerant, causing the above identified problems. In order to eliminate 
these problems and maintain the refrigerant in a gaseous state, 
compressors have been provided with external heaters to maintain an 
elevated temperature in the compressor crankcase. Thus, any liquid 
refrigerant in the compressor crankcase will be vaporized. 
Prior art heaters have been utilized, both internal and external. Internal 
heaters have previously been utilized with compressors by installing them 
in a heater well with a thermal mastic and a snap ring. However, the 
heater well is a potential leak source and the mastic is a messy 
production process. External heaters, mounted to the housing of the 
compressor, have been wrap-around designs attached with spring retention, 
screw clamps, adhesive strips, bolted, or welded. All of these mounting 
methods though are either awkward or unreliable over the expected life of 
the compressor and often do not provide good thermal transfer. 
It is therefore a object of the present invention to provide a mounting 
method for a crankcase heater whereby the heater can be quickly and easily 
mounted. 
It is therefore another object of the present invention to provide better 
thermal transfer from the heater to the crankcase sump. 
It is further an object of the present invention to provide a heater 
assembly that is simple and easy to assemble. 
SUMMARY OF THE INVENTION 
The present invention is a heater bracket and method of assembly which 
overcomes the problems of the prior art by utilizing a metal bracket which 
is welded to the compressor housing and a metal spring clip which securely 
holds the heater and resiliently biases the heater towards and against the 
housing. The bracket and clip, being metal, conduct the heat to the 
housing. 
Also, the heater is in direct contact with the compressor housing without 
the intermediary of adhesive strips, glue or the like. This allows for 
maximum heat transfer efficiency from the heater to the housing and 
therefore the crankcase. 
In addition to the above, the present invention is simple to assemble and 
disassemble should the heater need to be replaced. 
The present invention is a crankcase heater assembly for and in combination 
with a compressor comprising a bracket, a spring clip and a heater. The 
bracket has an elongated groove with a recess formed therein which 
receives the spring clip which has a center protrusion which engages the 
recess formed in the bracket, and resilient locking tabs for retaining the 
heater.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, a compressor 10 is shown having a housing 12, a 
discharge tube 13, and supports 14 and 15. Attached to compressor housing 
12, in a manner to be forthwith described in connection with the method of 
assembly, is heater assembly 16. 
Heater assembly 16, shown in more detail in FIG. 2, includes D-shaped PTC 
heater 18 having a flat or slightly concave side 20 for direct contact 
with compressor housing 12, and electrical leads 22 and 23 for supplying 
electrical power. Other types of heaters also may be used. As an 
alternative embodiment (not shown) the heater may be cylindrically shaped, 
which mates with and engages a corresponding depression in the compressor 
housing. A substantially D-shaped metal bracket 24 with outwardly 
projecting flanges 26 and 27 (shown in FIG. 3) mounted to housing 12 by 
spot welds 29 forms a channel with housing 12 open on both ends. Bracket 
24 has an elongated rectangular groove 28 and a square opening or recessed 
area 30 for slidably receiving resilient metal clip 32 made of spring 
steel. Clip 32 may be made from any resilient material, while opening 30 
may be of any suitable geometric shape. Metal clip 32, is axially 
symmetrical from its middle, having a center arcuate protrusion 34 which 
engages opening 30 in elongated rectangular groove 28 and two reverse "S" 
end portions or locking tabs 36 and 37. The first arcuate portions 36a and 
37a of reverse "S" locking tabs 36 and 37 extend radially inward, towards 
housing 12 when assembled, beyond the center axial plane of clip 32 
providing a spring locking effect on heater 18. Second arcuate portions 
36a and 37 extend radially outwardly to provide a camming effect that 
facilitates insertion of heater 18. Therefore, when assembled with heater 
18 received within bracket 24, center arcuate protrusion 34 is captured in 
opening 30 and resiliently engages bracket 24 while locking tabs 36 and 37 
resiliently engage the ends of heater 18 providing secure spring retention 
of heater 18. 
As shown in FIG. 4, when clip 32 is assembled in bracket 24, arcuate 
protrusion 34 is longer than opening 30 thereby resiliently biasing heater 
18 against housing 12 without intermediary materials. This provides 
excellent thermal conduction from heater 18 to housing 12 thereby heating 
the oil in the compressor sump. The heat maintains the refrigerant in a 
gaseous state. 
Also, clip 32 and bracket 24 conduct heat from heater 18 to bracket flanges 
26 and 27 which transfer heat to the compressor crankcase. 
The assembly of the present invention is herewith described with reference 
to FIG. 3. Bracket 24 is first spot welded to housing 12 according to 
conventional welding techniques, or fastened in any other suitable manner. 
Other mounting methods may be utilized, such as rivets, but welding is the 
preferred method since it is permanent, does not require pre-drilling of 
holes or otherwise and provides excellent thermal transfer characteristics 
described above. 
Once bracket 24 is secured to housing 12, clip 32 is inserted into bracket 
24 until arcuate protrusion 34 engages opening 30 (see FIG. 4). Heater 18 
is then inserted leadless end first into bracket 24. Since locking tabs 36 
and 37 extend radially inward, heater 18 encounters resistance to sliding 
engagement into bracket 24. Since, however, clip 32 is also resilient and 
has arcuate ends 36b and 37b, a camming action occurs against heater 18 
which pushes the tab corresponding to the end in which the heater is being 
inserted, away from housing 12 while at the same time biasing against 
heater 18. When heater 18 is fully inserted in bracket 24, both locking 
tabs 36 and 37 provide a resilient locking action against both ends of 
bracket 24 such that no movement of heater 18 may occur. 
Clip 32, therefore, resiliently holds heater 18 securely against housing 
12, providing retained contact of flat side 20 to housing 12 and excellent 
thermal heat transfer while at the same time conducting heat radiated from 
the heater to bracket 24 back to housing 12 through flanges 26 and 27. 
As an alternate embodiment (not shown) the clip may have only one reverse 
"S" locking tab and an inwardly projecting flange for supporting the 
heater. When assembling, the clip would be inserted flange downward, 
reverse "S" locking tab upward. 
While this invention has been described as having a preferred design, the 
present invention can be further modified within the spirit and scope of 
this disclosure. This application is therefore intended to cover any 
variations, uses, or adaptations of the invention using its general 
principles. Further, this application is intended to cover such departures 
from the present disclosure as come within known or customary practice in 
the art to which this invention pertains and which fall within the limits 
of the appended claims.