This invention relates to a governor for an internal combustion engine. More specifically, the invention relates to an air vane governor.
Governors are known for internal combustion engines to govern engine speed. Different types of governors may be used in different engines, including flyweight governors and air vane governors. An air vane governor typically includes a rotatable flywheel or other support member that supports a fan having a plurality of spaced apart fins that rotate with the flywheel. As the fins rotate, they generate an air flow that is deflected by a pivotable air vane. A resilient member, such as a governor spring, opposes the movement of the air vane, such that the governed speed is determined by the interplay between the movement of the air vane and the spring force of the governor spring.
In typical air vane governors, the governor spring is attached to the linkage between the air vane and the throttle valve. When the spring is attached to the linkage, the spring exerts a side force on the linkage. This side force can cause the linkage to rotate or bind, which can affect the stability of the governor and cause problems, such as hunting or surging in the engine.
The speed of the engine typically drops when a load is applied to the engine. This drop in engine speed is called “speed droop” and is a characteristic of a particular engine. The speed droop is determined, in part, by the spring rate and tension applied to the governor spring. Speed droop causes a loss of horsepower in the engine and can affect the reliable function of the engine, especially under certain engine conditions.
In one embodiment, the invention provides an engine that includes a stationary member, a crankshaft supported for rotation by the stationary member, and a flywheel rotatable in response to rotation of the crankshaft. A fan has a plurality of fins and is rotatable in response to movement of the flywheel. A movable air vane includes a surface that deflects air from the fins as the fins move with the flywheel. The engine also includes an intake passageway for intake air and a throttle lever including a throttle pivot point and a throttle linkage aperture. The throttle linkage aperture and the throttle pivot point define a first axis having a first side and a second side. A throttle valve is disposed in the intake passageway to control the flow of intake air. The throttle valve is movable in response to movement of the throttle lever. A throttle linkage is positioned to directly or indirectly connect the air vane and the throttle lever. The throttle linkage and the movable air vane are disposed on the first side of the first axis. A resilient member is directly or indirectly connected to the stationary member and the throttle lever at a resilient member aperture that is located on the throttle lever on the second side of the first axis. The resilient member is configured to apply a force to bias the throttle lever, and the resilient member aperture in the throttle lever, in a first direction away from the flywheel.
In another construction, the invention provides an engine that includes a stationary member, a crankshaft supported for rotation by the stationary member, an intake passageway for intake air, and a throttle valve disposed in the intake passageway to control the air flow through the passageway into the engine. A throttle lever is pivotable about a pivot point to move the throttle valve and an air vane governor includes a movable air vane. The movable air vane is operable to pivot the throttle lever between a first position and a second position. A single resilient member forms at least a portion of a connection between the stationary member and the throttle lever. The resilient member applies a force to the throttle lever to bias the throttle lever toward a wide open position.
In yet another construction, the invention provides an engine that includes a stationary portion and a crankshaft supported by the stationary portion and rotatable at a first speed in response to the combustion of an air-fuel mixture. A fan is rotatable at a second speed that is proportional to the first speed in response to rotation of the crankshaft and an air vane is positioned adjacent the fan and is pivotable about a pivot axis in response to rotation of the fan. A throttle lever is pivotally supported for rotation about a throttle axis and includes a throttle linkage aperture that cooperates with the throttle axis to define a first axis having a first side and a second side. The throttle lever is movable between a first position and a second position to vary the first speed. A linkage forms at least a portion of a connection between the air vane and the throttle lever such that the throttle lever moves in response to movement of the air vane. The linkage and the air vane are disposed on the first side of the first axis. A resilient member forms at least a portion of a connection between the stationary member and the throttle lever. The resilient member is disposed on the second side of the first axis.
Further constructions and advantages of the present invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the drawings.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
The present invention is further described with reference to the accompanying drawings, which show some embodiments of the present invention. However, it should be noted that the invention as disclosed in the accompanying drawings is illustrated by way of example only. The various elements and combinations of elements described below and illustrated in the drawings can be arranged and organized differently to result in embodiments which are still within the spirit and scope of the present invention.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
The engine 10 further includes an intake passageway 38 through which air travels into the combustion chamber of the engine 10. The intake passageway 38 includes an intake end 40 and an exhaust end 41. The air flow through the intake passageway 38 is controlled by a throttle valve 42 (shown in phantom in
With reference to
The throttle link 46 is attached to the throttle lever 50 at a throttle link aperture 58. As illustrated in
A resilient member is interconnected (that is, either directly or indirectly connected) between the bracket 18 and the throttle lever 50. The resilient member is connected to the throttle lever 50 at a resilient member aperture 74 on throttle lever 50. The resilient member applies a force to the throttle lever 50 that is directed generally away from the flywheel 34. Thus, the force opposes movement of the air vane 22 when the air vane 22 moves in one direction, and aids movement of the air vane 22 when the air vane 22 moves in the opposite direction. In the illustrated embodiment, the resilient member includes a spring 70. However, it is understood that in other embodiments, other types of resilient members such as torsion springs and compression springs, or multi-piece resilient members can be utilized, and also that the resilient member can be connected to portions of the fuel tank 14 other than the bracket 18. In some embodiments, the resilient member could be attached to an adjustable bracket on the stationary portion of the engine 10. Attaching the spring 70 to the throttle lever 50 eliminates the binding problems discussed above with respect to governors where the spring is attached to the throttle linkage. This makes the governing more stable and allows for less speed droop in the engine. With reference again to
The location of the resilient member aperture 74 affects the amount of droop in the engine 10, thereby affecting the stability of the governor. Locating the resilient member aperture 74 on the same side of the first axis 62 as the throttle link 46 increases the chance of the spring binding as the throttle lever 50 and the spring 70 are moved towards an overcenter position. To reduce the risk of binding, the resilient member aperture 74 is located on the opposite side of the first axis 62 from the throttle link 46. While it is understood that other locations of the aperture 74 on the opposite side of the first axis 62 are possible and still fall within the present invention, the location of the aperture 74 illustrated in
The size of the resilient member aperture 74 also affects the amount of droop in the engine 10 as well. If the aperture is too small, the manufacturability of the throttle lever 50 becomes more difficult, due to the tolerances of the machines. If the aperture is too large, the position of the spring 70 will change as the throttle lever 50 moves between the wide open throttle position and the closed position, due to the spring 70 sliding within the aperture. The change of position within the aperture can increase the droop in the engine. The diameter of the aperture 74 in the present invention should be between 0.041 inches (1.04 mm) and 0.060 inches (1.52 mm). In a preferred embodiment, the diameter is equal to 0.060 inches (1.52 mm).
The resilient member aperture 74 and the throttle pivot point 54 define a second axis 78, and the spring 70 defines a third axis 82. As illustrated in
In operation, the engine 10 combusts an air-fuel mixture to produce rotation of the crankshaft. The rotation of the crankshaft produces a rotation of the fan 26 at a speed that is proportional to the speed of the crankshaft. The air vane 22 deflects in response to the flow of air from the fan 26 to move the linkage or throttle link 46, which in turn pivots the throttle lever 50 to vary the flow of the air-fuel mixture and thus the speed of the engine 10. The spring 70 applies a force to the throttle lever 50 in a direction 100 that would move the throttle toward the wide open position (shown in
As illustrated in
It should be noted that the throttle link 46 may be just one component of a linkage and the spring 70 may be just one component of a biasing member. As such, the linkage and biasing member are described herein as forming at least a portion of a connection between two components. This terminology should be read to include constructions in which a single link (e.g., throttle link 46) and/or a single biasing member (e.g., spring 70) forms the entire connection and thus directly connects the two components. This terminology should also be read to include constructions in which the linkage includes several components directly connected to each other or connected to each other through one or more intermediate components, and the biasing member is but one of several components that are connected to one another to complete the connection between the two components.
Various features of the invention are set forth in the following claims.
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