U.S. patent number 3,743,452 [Application Number 05/245,588] was granted by the patent office on 1973-07-03 for liquid cooling system for rotary piston engines.
This patent grant is currently assigned to Audi Nsu Auto Union Aktiengesellschaft, Wankel GmbH. Invention is credited to Johannes Steinwart.
United States Patent |
3,743,452 |
Steinwart |
July 3, 1973 |
LIQUID COOLING SYSTEM FOR ROTARY PISTON ENGINES
Abstract
A liquid cooling system for a rotary piston, internal combustion
engine having cooling passageways, including an inlet cooling
passageway, in the engine housing which are connected together at
opposite ends to provide series flow of cooling liquid
therethrough, the system comprises a cooling liquid inlet port in
the engine housing communicating with a liquid cooler and the inlet
cooling passageway. An outlet port is provided in the engine
housing to connect the cooling passages with the liquid cooler to
pass heated cooling liquid to the latter. A liquid circulating pump
is disposed at the end of the engine housing opposite from the
inlet port and in communication with the inlet cooling passageway
to draw cooling liquid through the inlet port and inlet cooling
passageway and force cooling liquid through the other liquid
cooling passageways and the outlet port. A bypass passageway is
provided to communicate the other liquid cooling passageways with
the inlet port and inlet cooling passageway. A thermostatically
controlled valve is disposed at the inlet port to regulate flow
through the bypass passageway and, when fully open, permit flow of
cooling liquid to the inlet port via the bypass passageway and thus
bypass the liquid cooler.
Inventors: |
Steinwart; Johannes (Bad
Friedrichshall, DT) |
Assignee: |
Audi Nsu Auto Union
Aktiengesellschaft (Neckarsulm, DT)
Wankel GmbH (Lindau, Bodensee, DT)
|
Family
ID: |
5807386 |
Appl.
No.: |
05/245,588 |
Filed: |
April 19, 1972 |
Foreign Application Priority Data
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|
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May 10, 1971 [DT] |
|
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P 21 23 010.4 |
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Current U.S.
Class: |
418/84; 123/41.1;
418/87; 418/85; 418/88 |
Current CPC
Class: |
F02B
55/08 (20130101) |
Current International
Class: |
F02B
55/00 (20060101); F02B 55/08 (20060101); F01c
021/06 () |
Field of
Search: |
;418/61,83,84,87,88,85
;123/8.01,8.45,41.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Garrett; Robert E.
Claims
What is claimed is:
1. A cooling system for a rotary piston, internal combustion engine
having a plurality of cooling passageways, including an inlet
cooling passageway, in the engine housing which are interconnected
at opposite ends thereof to provide series flow of cooling fluid
therethrough, the cooling system comprising:
a. a cooler means for cooling a heated liquid coolant;
b. an inlet port at one end of the engine housing connected to said
cooler for receiving liquid coolant from the latter and
communicating with the inlet cooling passageway to pass liquid
coolant to the latter;
c. a circulating pump having an inlet means for receiving liquid
coolant and an outlet means for discharging pressurized liquid
coolant to the cooling passageways downstream from the inlet
cooling passageway;
d. the circulating pump being disposed at the end of the engine
housing opposite from the end of the engine housing where the inlet
port is located and with its inlet means in communication with the
inlet cooling passageway to draw liquid coolant from the
latter;
e. an outlet port adjacent said inlet port and in communication
with the cooling passageways to receive heated liquid coolant from
the latter and connected to the cooler to pass heated liquid
coolant to said cooler;
f. bypass passageway means communicating the cooling passageways
downstream from said circulating pump with the inlet port; and
g. a temperature responsive valve means disposed in the inlet port
to control flow of coolant through the bypass passageway means and
into said inlet port and inlet cooling passageway.
2. The apparatus of claim 1 wherein said plurality of cooling
passageways extend in substantially parallel relationship to each
other and the axis of rotation of the rotary piston of the
engine.
3. The apparatus of claim 1 wherein said inlet cooling passageway
extends in the engine housing in the area of highest heat flux.
4. The apparatus of claim 1 wherein said inlet cooling passageway
is relatively straight and unrestricted and has a flow area greater
than the flow area of the other cooling passageways.
5. The apparatus of claim 1 wherein said plurality of cooling
passageways extend in substantial parallel relationship to each
other and the axis of rotation of the rotary piston of the engine
and wherein said bypass passageway means includes a bypass
passageway which bypasses the valve means and communicates with the
outlet port and the cooling passageway downstream from the outlet
means of the circulating pump so that a portion of the coolant is
conducted directly to the outlet port when the valve means is in a
closed position preventing coolant flow into said inlet port
through the bypass passageway means.
6. A cooling system for rotary piston, internal combustion engine
having a plurality of cooling passageways, including an inlet
cooling passageway, extending between the end wall sections of the
housing and substantially parallel to each other and the axis of
rotation of the rotary piston, which cooling passageways are in
communication at opposite ends through header chambers in the
opposite end wall sections of the housing to provide series flow of
cooling fluid therethrough, the cooling system comprising:
a. a cooler means for cooling a heated liquid coolant;
b. the cooler means being connected to the inlet cooling passageway
at one end thereof in one of the end wall sections of the housing
for conducting cooled liquid coolant to the latter and in
communication with the cooling passageways to receive heated
cooling liquid from the latter;
c. a circulating pump disposed in the other end wall section of the
housing to communicate with the end of inlet cooling passageway,
opposite from the latter's connection with the cooler means, to
draw liquid coolant through the inlet cooling passageway;
d. said circulating pump being in communication with the other
plurality of cooling passageways to discharge coolant into the
latter;
e. bypass passageway means communicating the said other cooling
passageways with the inlet cooling passageway at the said one end
wall section of the housing; and
f. a temperature responsive valve means disposed in the said one
end wall section to control flow of coolant through the bypass
passageway means and into said inlet cooling passageway for
recirculation through the circulating pump.
7. The apparatus of claim 6 wherein said other end wall section is
the accessory drive end of the engine.
8. The apparatus of claim 6 wherein said inlet cooling passageway
is relatively straight with minimal restriction to coolant
flow.
9. The apparatus of claim 6 wherein said inlet cooling passageway
and circulating pump provides coolant flow in excess of the
capacity of the other cooling passageways, and wherein said bypass
passageway means includes a bypass passageway which conducts the
excess coolant flow to said cooler means.
10. The apparatus of claim 6 wherein said cooling passageways are
interconnected for series flow through header chambers formed in
the opposite end wall sections of the engine housing.
Description
The invention relates to rotary piston engines and, more
particularly, to a liquid cooling system for rotary piston,
internal combustion engines.
BACKGROUND OF THE INVENTION
In rotary piston, internal combustion engines of the type
exemplified in the U.S. PATS. to Bentele et al., No. 3,007,460;
Bentele, No. 3,062,435; and Turner No. 3,289,647, difficulty has
been encountered in effectively cooling the engines because of the
construction of the cooling passageways and the need to remove heat
at very high rates to prevent engine malfunction or overheating and
metal fatigue, particularly in the housing region adjacent to which
the combustion and expansion phases of the power cycle for each
rotor continuously occurs. To illustrate the cooling difficulties
encountered in a rotary piston, internal combustion engine, it
should be pointed out that at maximum speed and power (throttle
wide open) of a conventional reciprocating engine, the maximum heat
flux anywhere in the engine is approximately 70,000 BTU per hour
per square foot as compared with a heat flux of about 280,000 BTU
per hour per square foot in a rotary piston engine operating under
the same conditions. It is for these reasons it is essential to
provide as efficient a cooling system as possible. Present cooling
systems as exemplified in the U.S. PATS. to Schulz, No. 3,498,277;
Middendorf et al., No. 3,014,467; Waydak, No. 2,988,068; and Jones,
No. 3,359,952, are relatively expensive and complex and/or
relatively thermodynamically inefficient. In some cooling systems
for rotary piston, internal combusiton engines, the circulating
pump and the thermostatic valve are located adjacent each other on
the engine housing. This arrangement, because of the limited space
available, requires a number of relatively sharp bends in the
liquid flow passageways upstream and downstream from the
thermostatic valve. These bends produce resistance to flow,
requiring larger capacity circulating pumps than would otherwise be
necessary. Also, liquid flow into the pump is imperfect which
results in cavitation and reduction in output of the pump.
Accordingly, it is an object of the present invention to provide a
liquid cooling system for a rotary piston, internal combustion
engine which is of improved thermodynamic efficiency over existing
cooling systems.
Another object of this invention is to provide a liquid cooling
system for a rotary piston, internal combustion engine in which
system resistance to liquid flow to and into the ciruclating pump
is minimized so that the circulating pump size can be smaller than
circulating pumps in conventional systems of comparable size.
A further object of this invention is to provide for a rotary
piston, internal combustion engine, a liquid cooling system in
which full liquid cooling flow can be maintained in the cooling
flow passages in the hottest region of the engine housing during
the period when the liquid cooler of the system is being
bypassed.
A still further object of the present invention is to provide for a
rotary piston, internal combustion engine, a liquid cooling system
in which more space is made available for accessory devices at the
accessory drive end portion of the engine.
SUMMARY OF THE INVENTION
Therefore, this invention contemplates for a rotary piston,
internal combustion engine an improved liquid cooling system which
comprises a plurality of cooling passageways, including a straight,
relatively large inlet cooling passageway, which are connected
together at opposite ends to provide series flow of cooling liquid
through the cooling passageways. An inlet port is provided in the
engine housing at one end portion thereof, which port is in
communication with a liquid cooler to receive cooled liquid from
the latter and with the inlet cooling passageway to pass cooled
liquid to such passageway. An outlet port is provided in the engine
housing to communicate with the liquid cooling passageways to
receive heated cooling liquid from the latter and with the liquid
cooler to pass the heated cooling liquid to the cooler for cooling
before recirculation to the inlet port. A liquid circulating pump
is disposed at the end of the engine housing opposite from the
inlet port and in communication with the inlet cooling passageway
and the other cooling passageways to draw cooling liquid through
the inlet cooling passageway and force the same into and through
the other cooling passageways. A bypass passageway is provided to
communicate the other liquid cooling passageways with the inlet
port and inlet cooling passageway. A thermostatically controlled
valve is disposed at the inlet port to regulate flow through the
bypass passageway and, when fully open, permit flow of cooling
liquid to the inlet port, via the bypass passageway, and thus
bypass the liquid cooler.
In another aspect of this invention the inlet cooling passageway
and the cooling passageway receiving the discharge from the
circulating pump are located in the area of the engine housing
which is subjected to the highest heat flux so that during periods
when the thermostatically controlled valve is fully open and the
cooler is being bypassed there is circulation of cooling liquid
past the hottest area of the engine housing.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objectives and advantages of the present
invention will appear more fully hereinafter from a consideration
of the detailed description which follows when taken together with
the accompanying drawings wherein one embodiment of the invention
is illustrated, and in which:
FIG. 1 is a schematic drawing of the liquid cooling system
according to this invention;
FIG. 2 is an exploded view of a rotary piston, internal combustion
engine having a liquid cooling system shown in FIG. 1, the liquid
cooler and conduits being omitted; and
FIG. 3 is a transverse cross-sectional view through the engine
housing section in which a thermostatically controlled valve is
located.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Now referring to the drawings, the reference number 10 designates,
in general, the liquid cooling system according to this invention
which is for a rotary piston, internal combustion engine 12 having
liquid cooling passageways forming part of the liquid cooling
system. As best shown in FIG. 2 and for purposes of this
disclosure, engine 12 is shown and will be described as a single
rotor engine having a housing composed of a plurality of sections,
but it is to be understood that the invention is not limited to
such engine. The liquid cooling system of this invention has
application to rotary piston internal combustion engines having two
or more rotary pistons and comprising any number of housing
sections.
For illustration purposes only, engine 12 comprises three main
housing sections, an intermediate section 14 having an
epitrochoidal shaped internal surface 16 and two end wall sections
18 and 20. The housing sections 14, 18 and 20, when joined together
in a suitable manner, as by tie-bolts (not shown), define a cavity
in which a rotary piston (not shown) is disposed for rotation on a
shaft (not shown).
The end wall section 18 is provided with an inlet port 22 which
communicates through an opening 24 with a passage or channels 26
and 28 in intermediate section 16 and end wall section 20. The
opening 26 and channels 26 and 28 are in register to form a
relatively large, straight inlet passageway 30. The channel 28 in
end wall section 20, at the opposite end of passageway 30, serves
as a pump inlet or suction port for a centrifugal pump which has an
impeller 32 mounted for rotation in a scroll cavity 34 formed in
end wall section 20. The pump has a discharge port 36 which
communicates with a header chamber 38 formed in end wall section
20. The intermediate section 14 and the two end wall sections 18
and 20 are provided with a plurality of cooling liquid passageways
40, 42 and 44 which are similar to and extend substantially
parallel to inlet passageway 30. As shown in the drawings, each
passageway 40, 42 and 44 may comprise two or more streams formed by
sets of aligned channels in housing sections 14, 16 and 20. Each of
the passageways 30, 40, 42 and 44 are interconnected with each
other at their opposite ends with header chambers formed in end
wall sections 18 and 20 to thereby provide for serial flow of
cooling liquid through the passageways. The passageway 40 is in
communication at one end with header chamber 38 to receive cooling
liquid discharged by impeller 32 of the circulating pump. At its
opposite end as best shown in FIG. 3, passageway 40 communicates
with a transfer header chamber 48 in end wall section 18. The
passageway 42 communicates with transfer header chamber 48 and, at
the opposite end, with a second transfer header chamber 50 formed
in end wall section 20 (see FIG. 2). The passageway 44 connects, at
one end, with second transfer header chamber 50 in end wall section
20 to receive cooling liquid from the latter and, at the opposite
end, communicates with a discharge header chamber 52 in end wall
section 18 (see FIG. 3). The end wall section 18 is also provided
with an outlet passage and port 54 which communicates with
discharge header chamber 52.
The cooling system 10 further includes, as shown in FIG. 1, an
inlet conduit 70 which interconnects inlet port 22 of engine 12 and
cooler 56 and an outlet conduit 72 which is connected to cooler 56
and outlet passage and port 54 of engine 12. The cooler 56 may be
the conventional radiator employed in automobiles. The inlet
conduit 70 provides for conducting cooled liquid coolant from
cooler 56 to inlet port 22 of engine 12, while outlet conduit 72
provides for conducting heated liquid coolant from outlet passage
and port 54 to the cooler 56 where it is cooled before
recirculation to engine 12 via inlet conduit 70.
The cooling system 10, as thus far described, further includes a
thermostatic valve 66 disposed in inlet 22 in end wall section 18
of the engine housing and a relatively straight and unrestricted
inlet passageway interconnecting inlet 22 with a circulating pump
at end wall section 20 located at the opposite end of the engine
housing. This arrangement provides minimal restriction in liquid
flow to the circulating pump and eliminates cavitation in the
circulating pump so that the circulating pump functions at optimum
efficiency. Also, by disposing the thermostatic valve 66 at a point
remote from the circulating pump more room is provided at the end
wall section 20 (the accessory drive end).
As is best shown is FIG. 3, the cooling system 10 provides for
regulation of cooling liquid circulation and the partial or full
bypassing of cooler 56 during low temperature operation of engine
12. This regulation is achieved by providing in end wall section 18
bypass passageways 58, 60 and 62 and a bypass port 64. The bypass
passageways 58 and 60 communicate with discharge header chamber 52,
while bypass passageway 62 communicates with transfer header
chamber 48. The bypass port 64 is disposed to communicate inlet
port 22 and channel 24 of inlet passageway 30 with bypass
passageways 58, 60 and 62. To control flow of liquid coolant
through the bypass passageways 58, 60 and 62, as well as through
bypass port 64, a thermostatically controlled valve 66 is disposed
in inlet port 22. The valve 66 may be of any conventional type such
as the thermostat manufactured by Standard Thomsen Corp. of
Waltham, Massachusetts, and designated Model 4D001. The valve 66 is
constructed and arranged so that its movable valve element 68 is
reciprocatable relative to bypass port 64 to and from a seated or
closed position on bypass port 64 and an unseated or open position.
By locating the circulating pump at the accessory drive end portion
of the engine more room is available at this end of the engine for
other accessory equipment, such as an alternator, oil pump and the
like.
In the operation of cooling system 10, with thermostatic valve 66
in the open position as shown in FIG. 2, liquid coolant bypasses
outlet passage and port 54 by flowing through bypass passageway 58
and 60 and bypass port 64 into inlet port 22 and, thence, through
channel 24 and passageway 30 to the circulating pump. Also,
simultaneously with the aforesaid bypass flow, part of the liquid
coolant discharging from passageway 40 into transfer header chamber
48, flows through bypass passageway 62 and into inlet port 22, via
bypass port 64. This cooler bypass arrangement insures flow of
liquid coolant through the engine housing area or zone of highest
heat flux by recirculating cooling liquid through passageways 30
and 40 as well as through passageways 42 and 44. With bypass port
64 closed by thermostatic valve 66, bypass passageway 64 insures
that the passageways 30 and 40 adjacent the high heat flux zone of
the engine carries the total quantity of cooling liquid flow
required in that zone. This assurance of sufficient cooling effect
is achieved by flowing a quantity of liquid through passageways 30
and 40 which is in excess of the flow capacity of passageways 42
and 44 with such excess being passed through bypass passageway 62
and into outlet passage and port 54, via bypass passageway 60. As
an alternate arrangement, bypass port can be made to communicate
with channel 24 instead of outlet passage and port 54.
It is to be understood that while engine 12 is shown as having no
liquid cooling flow passageways in the cool zone 70 of the engine
housing, the invention is not limited thereto and, without
departing from the scope and spirit of this invention, the engine
may have cooling flow passages extending around the entire
circumference of the engine housing as disclosed in the U.S. Pat.
to Jones, No. 3,007,460.
It is believed now readily apparent that the present invention
provides a cooling system for a rotary piston, combustion engine,
which system provides a relatively large and unrestricted inlet
flow passageway into the circulating pump so that the pump can
function without cavitation and at optimum capacity and efficiency.
It is a system in which more space is made available at the
accessory drive end of the engine and in which optimum liquid
coolant flow adjacent the area or zone of highest heat flux is
maintained with thermostatic valve in the open or closed position.
It is also a cooling system where bypass recirculation is achieved
wholly within the engine housing when the thermostatic valve is in
the open position.
Although but one embodiment of the invention has been illustrated
and described in detail, it is to be expressly understood that the
invention is not limited thereto. Various changes can be made in
the arrangement of parts without departing from the spirit and
scope of the invention as the same will now be understood by those
skilled in the art.
* * * * *