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.

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.

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.