Note: Descriptions are shown in the official language in which they were submitted.
CA 02273060 1999-OS-27
Coaxial Coolant: Fittings
e-
BACKGROUND OF THE INVENTION:
The invention relates to coolant lines attached to a natural gas remote
pressure regulator
in an automobile. The natural gas pressure regulal:or is installed in a
cylinder which may
be in the trunk or bed of the vehicle or in an underbody location. The coolant
lines to the
regulator are typically 20 feet long. The purpose of the coolant, which is
typically at
195°-250° F, is to warm the regulator.
to
SUMMARY OF THE INVENTION:
This invention provides fittings, which allow coolant supply and return lines
to be routed
coaxially (one inside the other). The coaxial routing reduces heat loss to the
environment, simplifies routing, reduces labor cost, reduces material cost,
reduces
15 weight, and statistically reduces the likelihood of external hose damage
(e.g. half as many
hoses presented to the environment).
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be more clearly understood, the preferred
embodiment
2o thereof will now be described in detail by way of example, with reference
to the
accompanying drawings, in which:
Diagram 1 is a schematic view of a prior art coolant supply system for a gas
pressure
regulator;
Diagram 2 is a schematic view of a coolant supply system according to the
present
25 invention;
Figure lA is a side view of a first coaxial tee fitting according to a
preferred embodiment
of the present invention;
Figure 1B is an end view of the first coaxial tee;
Figure 1 C is a cross-sectional view of the first coaxial tee fitting;
30 Figure 1 D is a cross-sectional view of the first coaxial tee fitting
showing the joint
assembly;
CA 02273060 1999-OS-27
Figure 2A is a side view of a second coaxial tee fitting according to a
preferred
embodiment of the present invention;
Figure 2B is an end view of the second coaxial tee fitting;
Figure 2C is a cross-sectional view of the second coaxial tee fitting;
Figure 2D is a cross-sectional view of the second coaxial tee fitting showing
the joint
assembly;
Fig. 3A is a bottom view of a coaxial manifold according to a preferred
embodiment of
the present invention;
Fig. 3B is a side view of a coaxial manifold according to the preferred
embodiment;
Fig. 3C is a cross-sectional view of a coaxial manifold according to the
preferred
embodiment;
Fig. 3D is a cross-sectional view of a coaxial manifold according to the
preferred
embodiment showing the joint assembly;
Fig. 4 is a cross-sectional view of a coaxial manifold according to an
alternative
embodiment of the present invention;
Fig. 5 is a cross-sectional view of a coaxial tee sized for a 3/g" ID hose and
l/4" OD tube;
Fig. 6 is a cross-sectional view of a coaxial tee sized for a 3/8" ID hose and
5/16" OD tube;
and
Fig. 7 is a cross-sectional view of a hose sized for a 3/g" x 5/16" tee.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For convenience, the description refers to automotive applications for the
invention.
However, those skilled in the art will appreciate that there are number of
other
applications of the present invention, and such applications are within the
scope of this
invention.
The fittings according to the present invention may be made of injection
molded plastic,
cast metals, or machined from bar stock. In the preferred embodiment, the
fittings parts
are used as molded (or cast) with no additional machining. While the figures
show the
CA 02273060 1999-OS-27
configuration for plastic fittings, a person skilled i:n the art could modify
the design to
accommodate casting methods, and such variations are within the scope of this
invention.
Preferably, the inner fluid line is made of plastic and is permanently joined
to the fittings
by gluing or solvent welding at the time of assembly. The outer fluid line is
preferably a
conventional rubber hose, sealed to the fittings using conventional hose
clamps. For
most applications, some slight leakage between the 2 fluid paths is
permissible, and thus
it is not necessary to perfectly seal one path from the other.
Diagram 1 depicts a typical prior art application. Coolant flow to and from
the vehicle's
heater core is typically routed through 5/8" inside diameter ("ID") rubber
hose (not
shown). In order to channel coolant flow to the remote natural gas regulator
003, plastic
tees 001 and 002 are inserted in the coolant flow. Smaller rubber hoses
(typically 3/8")
004 are routed between the tees and the regulator. The lines 004 are typically
20 feet
long. The routing of the coolant inside the regulator (not shown) can be
accomplished in
accordance with a number of known configurations and is not a part of this
invention.
Diagram 2 provides an overview of the present invention. A "coaxial tee"
fitting 200 is
instead connected to tees 001 and 002. Port 210 receives the input flow from
tee 002
while port 220 returns the outlet flow to tee 001. lPort 230 is a co-axial
port, with
2o separate coaxial lines directing flow to and from tlne regulator 003. The
exterior hose 232
is shown, and would typically have the same outside diameter ("OD") as hoses
004 in
Diagram 1. A second (internal) fluid line, not shown in Diagram l, runs inside
hose 232
and serves to separate the "supply" and "return" flow paths. A new manifold
fitting 300
terminates the coaxial lines at the regulator, separating the supply from the
return flow so
that the regulator is heated. As before, the routing of the coolant inside the
regulator is
not shown. Thus, this invention simplifies the routing and reduces the surface
area of
coolant hose. By reducing the surface area, less heat is lost, and the
statistical likelihood
of hose damage is reduced. By simplifying the routing, labor, material cost,
and weight,
are reduced.
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Figure 1 A shows an exterior side view of a coaxial, tee 100. Tee 100 is
comprised of a
body 101, SAE hose barbs 102, and clamping sectiions 103. The left-hand port
serves as
the inlet port.
Figure 1 B shows an exterior end view of tee 100. As can be seen, the upper
port serves
as the outlet port. The remaining port handles flow in both directions. The
supply flow
(out to the regulator) occurs in the smaller diameter as shown. The return
flow (from the
regulator) occurs in the annular area as shown.
to Figure 1C shows a side cross-sectional view of tee 100. As noted, port 110
serves as the
inlet port and has a diameter 111 equal to the outside diameter (OD) of the
interior co-
axial line 112 (see Figure 1 D). Port 120 serves as the outlet port and has a
diameter 121
chosen so as to assure adequate flow in the transition from the annular flow
section (see
133 in Figure 1 D) of port 130 into the cylindrical flow area of port 120.
Coaxial port
130 has a diameter 131 chosen so as to assure that the area of the flow
annulus is as
required. Diameter 131 continues to point 132, which is its intersection with
diameter
121. Diameter 131 could be extended further to the: left, if desired.
Figure 1D shows a side cross-sectional view of the joint assembly. Rubber
hoses 114
2o and 122 are attached to ports 110 and 120, and are preferably clamped with
known
conventional hose clamps. The other ends of hose 114 and 122 connect to tees
002 and
001 (respectively) in Diagram 2. Hose 132 connects to outlet port 130 and is
clamped
with a conventional clamp. In a typical application, all three hoses are 3/8"
ID rubber
coolant hose (typ .69" OD). Tube 112 is placed inside hose 132 and carries the
supply
flow to the regulator. Tube 112 is preferably a thin-wall plastic tube. Tube
112 is
permanently joined to tee 100 at the time of assembly, by known means such as
gluing or
solvent welding. The permanent attachment ensurE;s that tube 112 cannot be
pulled out of
its bore by bending the hose assembly (such withdrawal would provide a flow
short-
circuit, reducing or eliminating flow to the regulator).
4
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Figure 2A shows an exterior side view of a second. coaxial tee 200. Tee 200 is
comprised
of a body 201, SAE hose barbs 202, and clamping sections 203.
Figure 2B shows an exterior end view of tee 200. As can be seen, the upper
port serves
as the outlet port and the bottom port serves as the inlet port. . The
remaining port
handles flow in both directions. 'The supply flow (out to the regulator)
occurs in the
smaller diameter as shown. The return flow (from the regulator) occurs in the
annular
area as shown (233 in Figure 2D).
l0 Figure 2C shows a side cross-sectional view of tee 200. As noted, Port 210
serves as the
inlet port and has a diameter 211 which is equal to or greater than the ID of
tube 212 (see
Figure 2D). Port 220 serves as the outlet port and has a diameter 221 chosen
so as to
assure adequate flow in the transition from the annular flow section of port
230 into the
cylindrical flow area of port 220. Coaxial port 230 has a diameter 231 chosen
so as to
assure that the area of the flow annulus is as required. Diameter 231
continues to point
232, which is its intersection with diameter 221. Diameter 214 is equal to the
OD of tube
212. Diameter 213 is equal to the ID of tube 212.
Figure 2D shows a side cross-sectional view of the joint assembly. Rubber
hoses 214
and 222 are attached to ports 210 and 220, and are preferably clamped with
known
conventional hose clamps. The other ends of hose 214 and 222 connect to tees
002 and
001 (respectively) in Diagram 2. Hose 232 connects to outlet port130 and is
clamped
with a conventional clamp. In a typical application, all three hoses are 3/8"
ID rubber
coolant hose (typ. .69" OD). Tube 212 is placed inside hose 232 and carnes the
supply
flow to the regulator. Tube 212 is preferably a thin-wall plastic tube. Tube
212 is
permanently joined to tee 200 at the time of assembly, by known means such as
gluing or
solvent welding. The permanent attachment ensures that tube 212 cannot be
pulled out of
its bore by bending the hose assembly (such withdrawal would provide a flow
short-
circuit, reducing or eliminating flow to the regulator).
5
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Figures 3A and 3B show a first embodiment of a coaxial manifold 300. Manifold
300 is
comprised of a body 301, SAE hose barb 302, and clamping section 303. Two
through
holes 304 are provided for bolts to pass through the manifold 300 and clamp it
to the
regulator's body. Supply flow out to the regulator and return flow from the
regulator
occurs as described in detail below.
Figure 3C shows a cross-sectional side view of manifold 300. As noted, Port
310 serves
as the supply port and has an ID 311 which is equal to or greater than the ID
of tube 312
(see 3D). The OD of ports 310 and 320 engage like female ports in the
regulator body
l0 and are sealed by O-rings 340, which reside in O-~..°ing glands 306.
Port 320 serves as the
return port and has a diameter 321 chosen so as to assure adequate flow in the
transition
from the annular flow section of port 330 into the cylindrical flow area of
port 320.
Coaxial Port 330 has a diameter 331 chosen so as to assure that the area of
the flow
annulus is as required. Diameter 331 continues to point 332, which is its
intersection
15 with diameter 321. Diameter 334 is equal to the OD of tube 312, and
continues to point
333. Point 333 is selected so as to ensure adequate bonding area between the
tube and
manifold 300. The port then drops to diameter 335, equal to the ID of tube
312, and
continues until its intersection with diameter 311.
20 Figure 3D shows a side cross-sectional view of the joint assembly.
Figure 4 shows an alternative embodiment of a manifold 400 with a thermostatic
control
added. Manifold 400 is generally identical to manifold 300, except as follows.
Manifold
400 is enlarged in area 451, providing a bore 452 fir the thermostat seat 471
to ride in.
25 Thermostat bore 452 intersects port bore 334. The; fit of piston 471 in
bore 452 is
selected so as to minimize leakage around the barrel of the piston when it is
fully seated
against stop 454. Spring 472 acts to open piston 4;~1 when the sensed
temperature is
"cold". A bearing 460 is inserted into bore 452 and is glued or solvent welded
to the
body 451. An o-ring 461 rides in bore 462, sealing bearing 460 to the shaft
470. Shaft
30 470 is inserted through bearing area 481 of thermostat 480. The thermostat
body 480 is
presumed to engage a mating cavity in the regulator body, thus sensing
regulator body
CA 02273060 1999-OS-27
temperature. When the body temperature is high, 'the sensing element 482
(preferably
wax) expands, acting against shaft 470, moving piston 471 to its seat, thus
shutting off
coolant flow. Alternatively, by relocating thermostat sensing element 480, the
thermostat
could sense either natural gas outlet temperature or coolant temperature.
Various uses may require different flow capacities. The chart below shows a
few
combinations of hose ID (132, 232,336) and tube (112, 212, 312) ID and OD. The
resultant equivalent flow diameters for the supply and return lines are also
shown. Only a
few of the many possible combinations are shown. Note that for each unique
to combination, a minimum diameter for dimension f31 also exists (assuming
131= 231=
331 ). That value is also shown below.
Tube Hose Equiv. ID 131
112 132 Flow
Dia.
ID OD ID Sunnly Return min. Example
0.1370.187 0.375 0.128 0.325 .227
0.1800.250 0.375 0.174 0.280 0.304 Fig.S
0.2320.313 0.375 0.209 0.207 0.376 Fig.6
0.1370.187 0.500 0.128 0.464 0.227
0.1800.250 0.500 0.174 0.433 0.304
0.2320.313 0.500 0.209 0.390 0.376
0.2750.375 0.500 0.255 0.330 0.454
0.3150.394 0.500 0.236 0.308 0.459
0.3940.472 0.500 0.261 0.164 0.540
Figure 5 is a cross-sectional side view of a typical application of fitting
100. In this case,
the fitting is sized for a 3/8" ID hose (132) and'/4" OD tube 112. Such a
fitting would
have a flow area equivalent to a .174" diameter tube. Per SAE specifications,
the OD of
the hose barbs 102 is .430". The bore diameter 131 of .305" is greater than
the .304"
minimum shown in the above table. Thus, for this fitting, standard hoses and
tubes could
be used.
7
CA 02273060 1999-OS-27
If the equivalent minimum flow diameter of the joint needed to be .207", the
above table
indicates that a standard 5/16" OD tube and 3/8" IiD would deliver that
performance.
However, the fitting would need its diameter 131 to be at least .376". Figure
6 is an
example of such a fitting, with 131 equal to .378." With a .035" wall
thickness, the
fitting's OD at port 130 is .450, and the hose barb OD is .505." Ports 110 and
120 would
retain the standard dimensions for a 3/8" hose as noted in Figure 5.
Notably, a standard 3/8" ID rubber hose (132, 232" 336) could not predictably
be
to installed onto the size of port 130 in Fig. 6 (too tight a fit). Instead,
such joints would be
accommodated by mandrel forming the hose ends to the larger (.450" ID) size so
that
they would install properly. The sizing of the hose: ends to fit the port of
Fig. 6 is shown
in Fig. 7.
8
