This invention is based on and claims priority to Japanese Patent Application No. Hei 11-293052, filed Oct. 14, 1999, the entire contents of which is hereby expressly incorporated by reference.
1. Field of the Invention
This invention relates to an engine throttle valve linkage, and more particularly to a throttle valve control linkage suitable for an outboard motor engine.
2. Description of Related Art
A typical outboard motor is powered by an internal combustion engine. The engine is disposed atop the outboard motor and is surrounded by a protective cowling. Normally, with increased engine performance (i.e., higher horsepower), the engine become larger. Because of this, the engine of large outboard motors are often V-shaped. The V-shaped engine usually has six or more cylinders to produce a large power output. Such engines also require a large cowling. It is, however, desirably to keep the cowling size as small as compact as possible in order to minimize drag on the watercraft.
With this design parameter in mind, a space in an internal cavity of the cowling is extremely limited, but nevertheless must accommodate many engine-related components. A throttle valve linkage is one of these components.
The engine includes an air induction system that is arranged to supply air to combustion chambers of the engine. The air induction system for the V-shape engine commonly includes a pair of air intake conduits that, for example, extend along both sides of the engine. Each intake conduit has a throttle valve that admits a desired amount of air to flow therethrough in response to various running conditions of the engine.
Generally, valve opening degrees of the respective throttle valves should be the same as each other. The throttle valves on the respective banks of the V-configuration are thus desirably controlled under a synchronized condition. A linkage system is provided for this synchronized control. It is, however, difficult to arrange the linkage system neatly and compactly in the narrow space between the engine side and a sidewall of the cowling.
If the engine requires a number of parts or members for arranging the valve linkage in the narrow space, another problem arises. The costs associated with manufacturing these parts and assembling them on the engine increases the overall production cost of the outboard motor.
In addition, because of separated in two intake conduits, the throttle valves on both banks may not synchronize accurately with each other. This situation can occur if the valve linkage is used for a long period or tolerances in manufacturing or assembling processes.
An improved throttle valve linkage system is provided within the space around the engine in the internal cavity of the protective cowling so as to control the throttle valves under a synchronized condition. In a preferred mode, the throttle valve linkage can adjust for discrepancies in the movement of the throttle valve on both banks so as to synchronize them accurately. In addition, the throttle valve linkage preferably is configured so as to be more easily arranged and assembled on the engine to reduce the manufacturing costs associated with the outboard motor. These aspects of the present invention may be practiced together or apart from each other.
In accordance with one aspect of the present invention, the throttle valve linkage system is used to control the throttle valves on both cylinder banks of the V-shaped internal combustion engine. The engine includes a cylinder block that defines at least two cylinder bores. The cylinder bores are arranged relative to each other in a V-shaped configuration. Pistons reciprocate within the respective cylinder bores. A cylinder head member closes one end of each of the cylinder bores and defines a combustion chamber with the respective cylinder bore and piston. A crankshaft is coupled to the pistons and a crankcase member closes the other ends of the cylinder bores. The cylinder block, the cylinder head member and the crankcase member together defines an engine body. A first air intake conduit communicates with one of the combustion chambers on one cylinder bank and extends generally along a side surface of the engine body. A second air intake conduit communicates with another one of the combustion chambers on the other cylinder bank and extends generally along another side surface of the engine body. The first air intake conduit has a first throttle valve that regulates an amount of air flow through the first air intake conduit. The second air intake conduit has a second throttle valve that regulates an amount of air flow through the second air intake conduit. A manipulator is provided for actuating both the first and second throttle valves. The manipulator includes a pair of manipulating members coupled with the first and second throttle valves. The manipulator is disposed generally between the first and second air intake conduits so as to be positioned on the engine body.
In accordance with another aspect of the present invention, an internal combustion engine comprises a cylinder block. The cylinder block defines at least two cylinder bores spaced apart from each other in a V-shaped configuration. Pistons reciprocate within the respective cylinder bores. Cylinder head members close the ends of the cylinder bores on one side and define combustion chambers with the cylinder bores and the pistons. A crankshaft is coupled with the pistons and a crankcase member closes the other ends of the cylinder bores. The cylinder block, the cylinder head member and the crankcase member together defines an engine body. A first air intake conduit communicates with one of the combustion chambers and extends generally along a side surface of the engine body. A second air intake conduit communicates with another one of the combustion chambers and extends generally along another side surface of the engine body. The first air intake conduit has a first throttle valve arranged for pivotal movement about a first valve axis. The second air intake conduit has a second throttle valve arranged for pivotal movement about a second valve axis. A manipulator is affixed to the engine body for pivotal movement about a third axis. The manipulator includes a pair of coupling rods connected to the first and second throttle valves. The first and second throttle valves pivot about the first and second axes, respectively, by the coupling rods when the manipulator pivots about the third axis.
In accordance with an additional aspect of the present invention, an internal combustion engine comprises a cylinder block. The cylinder block defines at least one cylinder bore. A piston reciprocates within the cylinder bore. A cylinder head member closes one end of the cylinder bore and defines a combustion chamber with the cylinder bore and the piston. The cylinder block further defines a lubricant passage through which lubricant passes. The lubricant passage has an open end. A closure member closes the open end. An air intake conduit communicates with the combustion chamber. The air intake conduit includes a throttle valve that regulates air flow to the combustion chamber. A valve actuator is arranged to actuate the throttle valve. The valve actuator is affixed to the closure member.
In accordance with a still further aspect of the present invention, an internal combustion engine comprises a cylinder block. The cylinder block defines at least two cylinder bores arranged in a V-shape configuration. Pistons reciprocate within the respective cylinder bores. Cylinder head members close the ends of the cylinder bores on one side of the engine and define combustion chambers with the cylinder bores and the pistons. A first air intake conduit communicates with one of the combustion chambers and a second air intake conduit communicates with another one of the combustion chambers. The first air intake conduit has a first throttle valve arranged to regulate the air flow through the first air intake conduit. The second air intake conduit has a second throttle valve arranged to regulate the air flow through the second air intake conduit. A manipulator simultaneously actuates both the first and second throttle valves. The manipulator includes a pair of connecting members coupled with the first and second throttle valves. An adjustment mechanism is arranged to adjust positions of both the first and second throttle valves so that the respective air flow through the first and second air intake conduits are generally same as each other. The adjustment mechanism is disposed between at least one of the connecting members and one of the first and second throttle valves.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiment which follows.