Coolant overflow bottle

A coolant overflow bottle is interposed between the centrifugal fan and the radiator for guiding air expelled by the fan toward the radiator. The bottle includes a top, a bottom, a pair of nested curved sidewalls, and a rear wall. The side walls are joined at a leading edge, and join the top and bottom. The rear wall is joined to the side walls at a trailing edge, and joins the top and bottom. The bottle wails define an exterior shape for guiding air.

FIELD OF THE INVENTION
 The field of the invention relates to engine cooling, more particularly to
 the cooling of liquid cooled internal combustion engines.
 DESCRIPTION OF THE BACKGROUND ART
 Vertical shaft internal combustion engines are becoming increasingly
 popular for use in lawn tractors. Their vertical shaft drives grass
 cutting blades without the use of a costly transmission. Consumer
 preferences, however, currently dictate lawn tractors with a low hood
 line. In a vertical shaft engine, this requires a short compact
 configuration. Even in larger tractors, such as those requiring an engine
 having 16 hp-35 hp, a low hood line is important to consumers. These
 larger engines, generate a significant amount of heat during operation and
 are typically liquid cooled. Liquid cooled vertical shaft engine are not
 easily shortened because of the necessity of a radiator to cool the liquid
 cooling the engine.
 Liquid cooled engines have cooling circuits which circulates liquid coolant
 to maintain a desired engine temperature. These cooling circuits have
 coolant bottles for receiving heated coolant which expands beyond the
 volume capacity of the cooling circuit. When the coolant in the cooling
 circuit cools, it contracts, drawing coolant from the bottle back into the
 cooling circuit. The coolant bottles, are generally located proximate the
 radiator, and attached to an external portion of the engine increasing the
 overall external engine dimension.
 SUMMARY OF THE INVENTION
 The present invention provides a coolant overflow bottle having an interior
 volume for receiving coolant for use with a liquid cooled internal
 combustion engine.
 The bottle includes a top, a bottom, and a pair of nested curved sidewalls
 joined at a leading edge, and joining the top and bottom. A rear wall is
 joined to the side walls at a trailing edge, and also joins the top and
 bottom. The bottle walls define an exterior shape for guiding air.
 In another aspect, the present invention provides a liquid cooled vertical
 shaft internal combustion engine having a cooling circuit for cooling the
 engine. The cooling circuit has a fluid flowing therethrough. The engine
 includes a cylinder block having a vertical shaft and passageways, the
 passageways being part of the cooling circuit. A centrifugal fan is
 mounted adjacent the engine block, and is driven by the vertical shaft for
 rotation about a vertical central axis. The fan draws air from a
 substantially axial direction and expels it in a substantially radial
 direction. A radiator mounted adjacent the cylinder block at least
 partially encircles the centrifugal fan in a path of the expelled air. The
 radiator is coupled to the cooling circuit for circulating cooling fluid
 therethrough. A coolant overflow bottle is interposed between the
 centrifugal fan and the radiator for guiding air expelled by the fan
 toward the radiator.
 A general objective of the present invention is to reduce the number of
 components required for an internal combustion engine. This objective is
 accomplished by providing a cooling bottle which also serves as an airflow
 guide.
 Another objective of the present invention is to provide a compact internal
 combustion engine. This objective is accomplished by locating the cooling
 bottle in a space between the fan and radiator.
 The foregoing and other objects and advantages of the invention will appear
 from the following description. In the description, reference is made to
 the accompanying drawings which form a part hereof, and in which there is
 shown by way of illustration a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Referring to FIGS. 1 and 2, the major elements of a vertical shaft internal
 combustion engine 10 include a cylinder block 12 with a rotatably mounted
 vertical shaft 14, a centrifugal fan 16 mounted on the shaft 14 and above
 the cylinder block 12, a radiator 18 encircling the fan 16, and an air
 duct 20 enclosing the fan 16 and radiator 18. The internal combustion
 engine 10 is liquid cooled by forcing a coolant, such as water, through a
 cooling circuit which includes the cylinder block 12 and the radiator 18.
 The cylinder block 12 has two cylinders 22 each having a head 24 disposed
 at one end. The cylinders 22 receive reciprocating pistons (not shown)
 which drive the vertical drive shaft 14. Operation of the internal
 combustion engine 10 generates heat in the cylinders 22 which heats the
 entire cylinder block 12. In order to cool the cylinders 22, coolant flows
 in passageways (not shown) surrounding each cylinder 22, and in each
 cylinder head 24. Although a two cylinder engine is described herein, the
 engine may have any number of cylinders without departing from the scope
 of the present invention.
 Referring to FIGS. 2 and 3, the passageways in the engine 10 form part of
 the cooling circuit which includes a manifold 26, thermostat (not shown),
 radiator 18 and a coolant pump 32. The cooling circuit defines a path for
 the coolant as it is subjected to a continuous heating and cooling cycle
 for cooling the engine 10.
 The coolant in the passageways is heated by the engine 10 and flows from
 the passageways into the manifold 26. The manifold 26 receives the coolant
 from the passageways in all of the cylinders 22 and cylinder heads 24, and
 channels it past the thermostat valve. The heated coolant from all the
 passageways is combined in the manifold 26 reducing any pressure
 fluctuations in the cooling circuit generated from any particular
 passageway.
 The thermostat valve disposed in the manifold 26 increases or decreases the
 flow of coolant through the circuit in response to the engine temperature.
 If the engine temperature falls below a certain threshold temperature, the
 flow of coolant through the circuit is decreased. If the engine
 temperature rises above a threshold temperature the flow of coolant
 through the circuit is increased. By controlling the flow of coolant
 through the circuit, the thermostat valve maintains the operating
 temperature of the engine 10 within a desired operating temperature range.
 As shown in FIGS. 1-3, the radiator 18 is formed from two annular segments
 36 and receives the heated coolant through a radiator hose 34 extending
 from the manifold 26. A radiator bracket 35 joins the two annular
 segments, and supports the radiator hose. The annular segments 36 are
 mounted to the cylinder block 12 and substantially encircle the
 centrifugal fan 16. The annular segments 36 are connected to the cooling
 circuit in parallel to quickly cool the flowing coolant. Providing annular
 segments 36 is preferred because the segments 36 are easier to manufacture
 than a single annulus. Alternative shapes, such as a polygon, dome, cone,
 or segments thereof, may be used to encircle the fan without departing
 from the scope of the present invention.
 Air is forced through the radiator 18 to cool the coolant in the cooling
 circuit by the centrifugal fan 16 mounted on the engine vertical shaft 14
 and above the cylinder block 12. The centrifugal fan 16 is disposed within
 the area surrounded by the radiator, and has a plurality of cupped fan
 blades 79 equidistantly spaced about a central fan axis 81. Outer edges 83
 of the fan blades 79 define a fan diameter. Although equidistantly spaced
 fan blades are described, staggered fan blades may also be used without
 departing from the scope of the present invention.
 Preferably, the fan blades 79 are formed as part of a flywheel 86 which is
 mounted to the vertical shaft 14. Rotation of the vertical shaft 14
 rotates the blades 79 about the fan central axis 81 drawing cooling air
 from the atmosphere in a generally axial direction toward the fan center.
 Air drawn into the fan center is propelled by the blades 79 in a generally
 radial direction toward the surrounding radiator 18. Although in a
 preferred embodiment, the fan 16 is formed as part of the flywheel 86, the
 fan 16 may be independently mounted to the shaft 14 or mounted to a
 different shaft driven by a drive mechanism, such as a gear box or belt
 drive, mounted to a vertical or horizontal shaft engine without departing
 from the scope of the present invention.
 Referring to FIG. 3, once the coolant is cooled by passing through the
 radiator 18, it exits the radiator outlet chamber 44 into radiator hoses
 37. The radiator hoses 37 direct the cooled coolant to the coolant pump 32
 which forces the coolant back into the passageways and through the cooling
 circuit to cool the engine 10
 Pressure caused by the coolant pump 32 and heated coolant inside the
 cooling circuit is controlled by a valve cap 78. The valve cap 78 is
 disposed above the radiator 18 and covers a fill opening in the cooling
 circuit. As the coolant absorbs heat generated in the engine 10, it
 expands increasing the pressure in the cooling circuit. The valve cap 78
 has an overflow port 79 communicatively connected to a coolant overflow
 bottle 82 by a vent tube 84. The bottle 82 receives excess coolant and gas
 in the cooling circuit which is vented through the valve cap 78.
 Preferably, the bottle 82 includes a vent 87 to allow the gas to escape to
 the surrounding atmosphere.
 The cooling circuit operates most efficiently when it is filled with
 coolant. Advantageously, the vent tube 84 between the coolant bottle 82
 and the radiator hose 34 allows coolant in the coolant bottle to 82
 replenish the circuit when the circuit pressure drops. When the engine 10
 stops operating, the coolant temperature drops creating a vacuum in the
 cooling circuit. The valve cap 78 allows coolant from the coolant bottle
 82 to flow back into the cooling circuit through the vent tube 84
 replenishing the circuit for the coolant displaced due to expansion.
 The coolant bottle 82 is interposed between the radiator 18 and the fan 16,
 and is shaped to guide air expelled by the fan 16 toward the radiator 18.
 A bottle bracket 83 extending from the radiator bracket 35 holds the
 bottle 82 in place. Preferably, the bottle 82 is a blow molded plastic
 injection bottle molded to have an exterior shape of an airflow baffle or
 fan volute. Advantageously, by locating the bottle 82 within the area
 surrounded by the radiator 18, the engine 10 is more compact.
 In one embodiment, shown in FIGS. 4 and 5, the bottle 82 has a top 100 and
 bottom 102 which are joined by a pair of nested curved side walls 104,
 106, a rear wall 108, and a front wall 110 narrower in width than the rear
 wall 108 to form an airfoil shape, such as an arcuate wedge. In
 particular, the side walls 104, 106 are joined at one edge to the front
 wall 110 define a leading edge at a bottle front, and opposing side wall
 edges are joined to the rear wall 108 to define a trailing edge. Of
 course, the front wall 110 could be eliminated, and the leading edge can
 be formed by joining the side wall edges together. Lips 111 extending
 outward from one curved side wall 106 rest on a lower radiator bracket 113
 to support the bottle 82 when in place.
 The bottle top 100 has an opening 112 which is covered by a conventional
 overflow cap 114 with a vent port 116 in fluid communication with the vent
 tube 84. The bottle 82 conventionally receives overflow coolant from the
 coolant system through the vent port 116. The top 100 also includes an
 integral upwardly extending tab 118 which engages the bottle bracket 83 to
 hold the bottle 82 in place.
 Alternatively, the bottle can be strategically mounted to the engine, or in
 the engine compartment, to take advantage of the shape of the bottle to
 guide the air flow through the fan or radiator to increase cooling
 efficiency. Advantageously, the multifunction bottle can replace a
 conventional air baffle or fan volute to reduce the number of required
 engine parts.
 The air duct 20 encloses, and is mounted to the radiator 18 to guide air
 through the radiator 18. Preferably, the duct 20 is formed from
 conventional materials, such as plastic or metal. Although the air duct 20
 as described herein is mounted to the radiator 18, the air duct 20 may be
 mounted to any suitable component or bracket of the engine 10, such as to
 the cylinder block 12 or bracket affixed thereto, without departing from
 the scope of the present invention.
 Looking particularly at FIG. 1, the air duct 20 is shaped having a top
 plate 90 and downwardly depending sides 92 to enclose the fan 16 and
 radiator 18 and control the flow of cooling air into and out of the
 radiator 18. The fan 16 draws cooling air into the duct 20 through a
 circular aperture 94 formed in the top plate 90. Preferably, the circular
 aperture 94 has a diameter smaller than the fan diameter and is
 substantially concentric with the fan axis 81. By providing an aperture
 diameter smaller than the fan diameter, air is channeled into the fan
 center which increases the fan efficiency and minimizes any excess air
 from escaping in the axial direction, thus maximizing the cooling air
 which passes the radiator 18.
 The duct downwardly depending sides 92 enclose a portion of the radiator 18
 to deflect the air which has passed through the radiator 18 downward.
 Advantageously, by deflecting the air downward, the heated cooling air
 which has passed through the radiator airways is directed toward the
 engine 10 to further cool the cylinder block 12.
 While there has been shown and described what are at present considered the
 preferred embodiment of the invention, it will be obvious to those skilled
 in the art that various changes and modifications can be made therein
 without departing from the scope of the invention.